Superconducting joining of melt-textured Y-Ba-Cu-O bulk material

The Tm-Ba-Cu-O solder can be successfully used to produce a superconductive joint between MT-YBCO parts. The peculiarities of solidification, phase formation, structure transformations and electromagnetic properties of MT-YBCO soldered with TmBa2Cu3O7-d are discussed.Comment: PS of 6 pages text and 5 figures, presented at ICMC'2000, Brasi

Inter- and intragrain currents in bulk melt-grown YBaCuO rings

A simple contactless method suitable to discern between the intergrain (circular) current, which flows in the thin superconducting ring, and the intragrain current, which does not cross the weakest link, has been proposed. At first, we show that the intergrain current may directly be estimated from the magnetic flux density $B(\pm z_0)$ measured by the Hall sensor positioned in the special points $\pm z_0$ above/below the ring center. The experimental and the numerical techniques to determine the value $z_0$ are discussed. Being very promising for characterization of a current flowing across the joints in welded YBaCuO rings (its dependencies on the temperature and the external magnetic field as well as the time dissipation), the approach has been applied to study corresponding properties of the intra- and intergrain currents flowing across the $a$-twisted grain boundaries which are frequent in bulk melt-textured YBaCuO samples. We present experimental data related to the flux penetration inside a bore of MT YBaCuO rings both in the non-magnetized, virgin state and during the field reversal. The shielding properties and their dependence on external magnetic fields are also studied. Besides, we consider the flux creep effects and their influence on the current re-distribution during a dwell.Comment: 13 pages, 16 figures (EPS), RevTeX4. In the revised version, corrections to perturbing effects near the weak links are introduced, one more figure is added. lin

PINK1 Is Necessary for Long Term Survival and Mitochondrial Function in Human Dopaminergic Neurons

Parkinson's disease (PD) is a common age-related neurodegenerative disease and it is critical to develop models which recapitulate the pathogenic process including the effect of the ageing process. Although the pathogenesis of sporadic PD is unknown, the identification of the mendelian genetic factor PINK1 has provided new mechanistic insights. In order to investigate the role of PINK1 in Parkinson's disease, we studied PINK1 loss of function in human and primary mouse neurons. Using RNAi, we created stable PINK1 knockdown in human dopaminergic neurons differentiated from foetal ventral mesencephalon stem cells, as well as in an immortalised human neuroblastoma cell line. We sought to validate our findings in primary neurons derived from a transgenic PINK1 knockout mouse. For the first time we demonstrate an age dependent neurodegenerative phenotype in human and mouse neurons. PINK1 deficiency leads to reduced long-term viability in human neurons, which die via the mitochondrial apoptosis pathway. Human neurons lacking PINK1 demonstrate features of marked oxidative stress with widespread mitochondrial dysfunction and abnormal mitochondrial morphology. We report that PINK1 plays a neuroprotective role in the mitochondria of mammalian neurons, especially against stress such as staurosporine. In addition we provide evidence that cellular compensatory mechanisms such as mitochondrial biogenesis and upregulation of lysosomal degradation pathways occur in PINK1 deficiency. The phenotypic effects of PINK1 loss-of-function described here in mammalian neurons provides mechanistic insight into the age-related degeneration of nigral dopaminergic neurons seen in PD

HtrA2/Omi Terminates Cytomegalovirus Infection and Is Controlled by the Viral Mitochondrial Inhibitor of Apoptosis (vMIA)

Viruses encode suppressors of cell death to block intrinsic and extrinsic host-initiated death pathways that reduce viral yield as well as control the termination of infection. Cytomegalovirus (CMV) infection terminates by a caspase-independent cell fragmentation process after an extended period of continuous virus production. The viral mitochondria-localized inhibitor of apoptosis (vMIA; a product of the UL37x1 gene) controls this fragmentation process. UL37x1 mutant virus-infected cells fragment three to four days earlier than cells infected with wt virus. Here, we demonstrate that infected cell death is dependent on serine proteases. We identify mitochondrial serine protease HtrA2/Omi as the initiator of this caspase-independent death pathway. Infected fibroblasts develop susceptibility to death as levels of mitochondria-resident HtrA2/Omi protease increase. Cell death is suppressed by the serine protease inhibitor TLCK as well as by the HtrA2-specific inhibitor UCF-101. Experimental overexpression of HtrA2/Omi, but not a catalytic site mutant of the enzyme, sensitizes infected cells to death that can be blocked by vMIA or protease inhibitors. Uninfected cells are completely resistant to HtrA2/Omi induced death. Thus, in addition to suppression of apoptosis and autophagy, vMIA naturally controls a novel serine protease-dependent CMV-infected cell-specific programmed cell death (cmvPCD) pathway that terminates the CMV replication cycle

QUANTUM STATISTICAL THEORY OF SATURATION OF FERROMAGNETIC RESONANCE UNDER PARALLEL PUMPING

On analyse par la statistique quantique les processus non linéaires qui déterminent le comportement stationnaire des magnons en pompage parallèle, au-delà du seuil critique. On part de la méthode des fonctions de corrélation de déséquilibre et on utilise l'équivalence entre les équations de Kadanoff-Baym et l'équation de Langevin du mouvement Brownien. On calcule la susceptibilité r. f. de l'état stationnaire et on la compare aux valeurs mesurées au cours des processus directs de fusion : 2 magnons → 1 magnon et 2 magnons → 1 phonon.A quantum statistical analysis of nonlinear mechanisms is described which establishes the steady state behaviour during spinwave parallel pumping above the critical threshold. The considerations are based on the method of non-equilibrium correlation functions and use the equivalence between the Kadanoff-Baym equations and the Langevin equation of Brownian motion. Special calculations of the steady state r. f. susceptibility are outlined and compared to the experiment which arise from three magnon and two magnon-one phonon confluence processes

Korrelation zwischen der Realstruktur und den physikalischen Eigenschaften von HTSL-Einkristallen und -Schichten Abschlussbericht

1. Mittels Phasendiagrammuntersuchungen sowie Kristallisationsexperimenten bei unterschiedlichem Sauerstoffpartialdruck wurde das primaere Kristallisationsfeld des YBCO bestimmt und die isotherme Zuechtung ermoeglicht. 2. Es wurden aus Hochtemperaturloesungen YBCO-Einkristalle hoher kristallographischer Perfektion hergestellt und Aussagen zum Verstaendnis der Flussverankerung gewonnen. 3. Mittels Fluessigphasenepitaxie (LPE) von YBCO auf NdGaO_3- und LaGaO_3-Substraten sind c- und (international erstmalig) a,b-Schichten mit Einkritallqualitaet (Tc#approx#90 K, #DELTA#T#<=#0.5 K) hergestellt und strukturell wie auch magnetisch charakterisiert worden. 4. Erste schmelztexturierte YBCO-''Einkristalle'' haben intrakristalline Stromdichten > 10"4 A/cm"2 bei Induktionen bis zu 2 T und Rreversibilitaetsinduktionen bis 6 T bei 77 K. Zusammen mit Kooperationspartnern wurden Vorstellungen zum Wachstumsmechanismus entwickelt und publiziert. 5. Insbesondere mit torsionsmagnetometrischen Untersuchungen ist es gelungen, intrinsische von realstrukturbedingten Effekten abzutrennen und damit die Moeglichkeiten einer gezielten Beeinflussung der Pinningeigenschaften abzugrenzen. 6. Die im wesentlichen eigenstaendigen Beitraege zur Theorie magnetischer Messverfahren fuehrten zur Separation von geometrischen und apparativen Einfluessen und damit zu einer klaren Interpretation magnetischer Messungen, insbesondere der Torsionsmagnetometric und der ac-Suszeptometrie. (orig./MM)1. In order to carry out isothermic crystal growth experiments of YBCO the 123 primary crystallization field was determined by means of phase diagram investigations and crystal growth experiments at different oxygen partial pressure. 2. YBCO single crystals of high crystallographic perfection were grown and conclusions on the flux pinning mechanism were drawn. 3. By means of Liquid Phase Epitaxy (LPE) single crystalline (Tc#approx#90 K; #DELTA#T#<=#0.5 K) c-and a,b- YBCO fils have been prepared on NdGaO_3 and LaGaO_3 substrates. The films were characterized structurally and magnetically. 4. Our fist melt textured YBCO ''single crystals'' possess intracrystalline critical current densities >10"4 A/cm"2 at B#<=#2T. The irreversibility inductions are #<=#6 T at 77 K. A simple demonstrator was constructed together with the IFW Dresden and a growth model was developed. 5. Using above all torque magnetometer measurements we separated intrinsic pinning effects from effects which are reasoned by the microstructure. 6. Own contributions to the theory of magnetic measuring methods resulted in the separation of geometric influences and influences of experimental arrangement, what leads to a clear interpretation of magnetic measurements carried out mainly with torque magnetometry and ac-susceptometry. (orig./MM)Available from TIB Hannover: D.Dt.F.QN1(7,27) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEBundesministerium fuer Forschung und Technologie (BMFT), Bonn (Germany)DEGerman

Texturierte HTSL-Massivmaterialien - Synthese und Charakterisierung. Teilvorhaben: Synthese und Anwendung von schmelztexturiertem YBCO-Material Abschlussbericht

Available from TIB Hannover: DtF QN1(76,45) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEBundesministerium fuer Bildung und Forschung (BMBF), Bonn (Germany)DEGerman

Design, solid-phase synthesis, and biological evaluation of novel 1,5-diarylpyrrole-3-carboxamides as carbonic anhydrase IX inhibitors

Following previous studies we herein report the synthesis and the pharmacological evaluation of a new class of human carbonic anhydrase (hCA) inhibitors, 1,5-diarylpyrrole-3-carboxamides prepared by a solid-phase strategy involving a PS(HOBt) resin. A molecular modeling study was conducted in order to simulate the binding mode of this new family of enzyme inhibitors within the active site of hCA IX. This study revealed that the 3-position of the pyrrole was opened to the solvent, so we introduced an amino side-chain, protonated at physiological pH both to enhance the aqueous solubility and to decrease the cell membrane penetration. This strategy consisted of preparing membrane-impermeant inhibitors that may selectively target the tumor-associated hCA IX. Physico-chemical characterizations including aqueous solubility and lipophilic parameters are described. Pharmacological studies revealed high hCA IX inhibitory potency in the nanomolar range. Some compounds are selective for hCA IX displaying hCA I/hCA IX and hCA II/hCA IX ratios higher than 20 and 5, respectively. (C) 2010 Elsevier Ltd. All rights reserved