Flux creep and fishtail in melt-textured and single-crystalline YBa2Cu3O7

Time-dependent decay of the magnetic moment and magnetization measurements were used to study pinning and flux creep in two samples with and without aj(B) maximum in nonzero field (fishtail effect). From both measurements theE(j) relation was reconstructed forBc and the characteristic current exponent was obtained. At highj and lowB values are between 1 and 4; with increasingB passes a maximum and approaches negative values. At lowj is below 0.5 and not dependent onB orj. This behavior, which is qualitatively the same in both samples, is compared with proposed phase diagrams of the vortex lattice. Large values are correlated with the plateau of the normalized creep rateS 0.025; both observations indicate low relaxation and are found in that lowB region for whichj(B) has its minimum. This observation rejects a dominating influence of relaxation on the fishtail effect.     

Kristallin-flüssige 1,3,4-Thiadiazole. II [1]. 1,3,4-Thiadiazole mit Cyclohexanstrukturfragmenten

Liquid Crystalline 1,3,4-Thiadiazoles. II. 1,3,4-Thiadiazoles with Cyclohexanefragments Preparation and liquid crystalline properties of disubstituted 1,3,4-thiadiazoles (1 and 2) are described. The mesomorphic behaviour of the title compounds is compared with their benzoate analogues. The dielectric anisotropy of these compounds is negative.     

Synthese und Eigenschaften kristallin-flüssiger Derivate des Rhodanins

Synthesis and Properties of Liquid Crystalline Derivatives of Rhodanine Substituted benzylidene-rhodanines 3 – 8 were prepared both by condensation of 1 a – f with suitable aldehydes and by acylation of 2a – g with substituted benzoyl chlorides or cinnamoyl chlorid. The mesomorphic properties of the compounds are discussed in respect to molecular structure with the aid of i.r.-, Raman- and u.v./vis-spectra of 3d , 3k , 4 , 5 , 6g , 8a . We have investigated the dielectric and electrooptic behaviour of 31 .     

Generality and legibility in mobile manipulation

This article investigates methods for achieving more general manipulation capabilities for mobile manipulation platforms, which produce legible behavior in human living environments. To achieve generality and legibility, we combine two control mechanisms. First of all, experience- and observation-based learning of skills is applied to routine tasks, so that the repetitive and stereotypical character of everyday activity is exploited. Second, we use planning, reasoning, and search for novel tasks which have no stereotypical solution. We apply these ideas to the learning and use of action-related places, to the model-based visual recognition and localization of objects, and the learning and application of reaching strategies and motions from humans. We demonstrate the integration of these mechanisms into a single low-level control system for autonomous manipulation platforms.     

Effect of clofibric acid on the turnover of the fatty acid-binding protein identified in cultured endothelial cells from bovine aorta

Several types of fatty acid-binding proteins are found in mammalian cells. Cultured endothelial cells from bovine aorta were shown to contain exclusively the cardiac-type fatty acid-binding protein (cFABP) with a mean concentration of 90 ng cFABP/mg extract protein. Only small variations were observed from passage to passage. In pulse-chase labeling experiments with L-[³⁵S]methionine, a half-life of 4.0 d was measured for cFABP which is about two times longer than the average half-life of the extracted proteins. These data imply that in aortic endothelial cells cFABP is not subject to short-term regulation. However, addition of clofibric acid to the culture medium led to a shortening of the half-life of cFABP, which was compensated for by an increase in its biosynthesis. The turnover of the bulk of extract proteins remained unchanged when the cells were challenged with clofibric acid.     

New enzyme lineages by subdomain shuffling

Protein functions have evolved in part via domain recombination events. Such events, for example, recombine structurally independent functional domains and shuffle targeting, regulatory, and/or catalytic functions. Domain recombination, however, can generate new functions, as implied by the observation of catalytic sites at interfaces of distinct folding domains. If useful to an evolving organism, such initially rudimentary functions would likely acquire greater efficiency and diversity, whereas the initially distinct folding domains would likely develop into single functional domains. This represents the probable evolution of the S1 serine protease family, whose two homologous beta-barrel subdomains assemble to form the binding sites and the catalytic machinery. Among S1 family members, the contact interface and catalytic residues are highly conserved whereas surrounding surfaces are highly variable. This observation suggests a new strategy to engineer viable proteins with novel properties, by swapping folding subdomains chosen from among protein family members. Such hybrid proteins would retain properties conserved throughout the family, including folding stability as single domain proteins, while providing new surfaces amenable to directed evolution or engineering of specific new properties. We show here that recombining the N-terminal subdomain from coagulation factor X with the C-terminal subdomain from trypsin creates a potent enzyme (fXYa) with novel properties, in particular a broad substrate specificity. As shown by the 2.15-A crystal structure, plasticity at the hydrophobic subdomain interface maintains activity, while surface loops are displaced compared with the parent subdomains. fXYa thus represents a new serine proteinase lineage with hybrid fX, trypsin, and novel properties.     

Decorin, biglycan and their endocytosis receptor in rat renal cortex

BACKGROUND: Among the small proteoglycans, biglycan and decorin have been proposed to be potent modulators of TGF-beta-mediated inflammatory kidney diseases. They were considered to become induced during glomerulonephritis and to subsequently inactivate the cytokine. METHODS: Decorin and biglycan as well as their endocytosis receptor were investigated in normal rat renal cortex, in anti-Thy-1 glomerulonephritis, in polycystic kidneys, in the remnant kidney following 5/6-nephrectomy, and in kidneys from the Milan normotensive strain by immunohistochemistry and in situ hybridization. Northern blots were used for the detection of mRNA expression for decorin and biglycan in isolated glomeruli. Functional aspects of the endocytosis of decorin and biglycan were studied in cultured mesangial cells. RESULTS: In the normal adult rat kidney decorin was expressed preferentially by Bowman's capsule and by interstitial connective tissue cells, but only in trace amounts by mesangial cells. In contrast, biglycan was found in tubular epithelial cells, in association with glomerular capillaries, podocytes and occasionally in the mesangium. In the tubulointerstitium of diseased kidneys (polycystic kidneys, 5/6-nephrectomy, kidneys from the Milan normotensive strain) there was a general up-regulation of decorin expression, while biglycan was localized only in distinct foci of fibrotic lesions. Glomerulosclerosis (5/6-nephrectomy, Milan normotensive strain) was associated with an increased staining for both decorin and biglycan within glomeruli. However, even in the anti-Thy-1 model of an acute mesangioproliferative glomerulonephritis where the greatest accumulation of decorin was found there was only a slight enhancement of decorin mRNA in isolated glomeruli. Decorin and biglycan become degraded upon receptor-mediated endocytosis. Immunohistochemical investigations indicated that the pattern of expression of the receptor protein correlated well with the immunolocalization of both decorin and biglycan. In vitro experiments with cultured mesangial cells provided direct evidence for the expression of the receptor and for the cell's capability to endocytose decorin as well as biglycan. CONCLUSIONS: Decorin and biglycan are characterized by a distinct expression pattern in the normal rat kidney, whereas the presence of their endocytosis receptor protein correlates with the expression of both proteoglycans. Decorin is almost completely absent in the normal mesangium. Both proteoglycans become up-regulated in various models of renal disease. The mesangial accumulation of decorin in the anti-Thy-1 glomerulonephritis that is observed in spite of the only slightly enhanced mRNA expression could result from decreased decorin turnover and/or increased mesangial retention.     

Laser writing on oriented polymer films

Polymer films are suitable substrates for optical data storage due to their mechanical and optical properties. Furthermore, oriented polymer films show an additional effect to laser writing. In this review the effects of laser writing on oriented polymer films are investigated by atomic force microscopy. A change in surface topography of the film is observed. Different polymer types and different draw ratios are used. The dependence of topography effects on the draw ratio is shown. A model of the writing effect is framed.     

Present State of an Ultrasonic Cross-Section Procedure with Rapid Image Rate

The scan unit attains a rapid-image rate by rotating the sound source at a frequency of about 16 Hz in the focal point of an acoustic cylindrical paraboloid mirror. By this arrangement a scanning beam is obtained that moves with a speed of about 2 m/s transverse to the direction of propagation of the ultrasound. This scanning speed permits the buildup of a sectional image within about 60 ms with an image frequency of about 16 Hz. As the scanning procedure is automatic and not manual, a high degree of objectivity is obtained with respect to imaging of contours and particularly of inhomogeneous tissues. The above-mentioned image frequency also permits visualization of kinetic processes inside the body; these can be viewed on the fluorescent screen or filmed.