Search Results - (Author, Cooperation:P. Jablonski)

2012-07-13

Nature Publishing Group (NPG)

0028-0836

1476-4687

Biology

Chemistry and Pharmacology

Medicine

Natural Sciences in General

Physics

Animals ; *Biological Evolution ; Biology/*education ; Humans ; *Religion and Science ; *Textbooks as Topic

1089-7550

AIP Digital Archive

Physics

Artificial pinning center (APC) Nb 47 wt % Ti composite wires containing 24 vol % Nb pins were characterized as the wire diameter was reduced. As the nominal pin diameter dp was reduced from 165 to 15 nm, the nominally round pins transformed into ribbons with a relatively wide distribution in thickness, as compared to the α-Ti ribbons in optimized, conventionally processed Nb 47 wt % Ti. The maximum in the bulk flux pinning force Fp of 25 GN/m3 (4.2 K, 2.5 T) occurred at dp=40 nm, for which the measured Nb ribbon thickness ranged from 1 to 16 nm. This Fp value was about one third higher than that found in the best conventional Nb 47 wt % Ti. The upper critical magnetic field Hc2, measured by magnetization, decreased from 10.3 to 9 T as the Nb pins became proximity-effect coupled to the matrix. To better compare APC and conventional wires, we measured the properties of the best APC wire at a reduced temperature so that its Hc2 was the same as Hc2(4.2 K) for Nb 47 wt % Ti. The peak value of Fp was then 36 GN/m3 at 3 T, almost twice the maximum value yet reported for conventional Nb–Ti (∼19 GN/m3 at 5 T). In spite of the pinning force curve remaining sharply peaked at lower fields, the equalized 5 T critical current density was 4600 A/mm2, some 25% higher than the best values of conventional Nb–Ti. These properties demonstrate the strong potential of APC composites. © 1996 American Institute of Physics.

Electronic Resource

1077-3118

AIP Digital Archive

Physics

The transport critical current density increased from 2610 to 5200 A/mm2 at 5 T, 4.2 K, when a round monofilament Nb 47 wt. % Ti composite was rolled to an aspect ratio of 9.7 and was tested with the broad face of the tape parallel to the field. This value exceeds the previous maximum of 3700 A/mm2 by about 50%. Transmission electron micrographs show that more than 90% of the α-Ti precipitates in the optimum-rolled filament are aligned within 10° of the broad face of the tape, whereas the precipitates had a random azimuthal orientation prior to rolling. The strong alignment caused the elementary pinning force to be greatly enhanced in the parallel-field orientation; however, in the orthogonal orientation the Jc fell to low values characteristic of conventional wires having no α-Ti flux pinning centers.

Electronic Resource

1077-3118

AIP Digital Archive

Physics

Several techniques to form artifical high critical current density superconducting Nb-Ti nanostructures have been reported. A drawback to virtually all of these techniques is that they require fabrication strains of 30 or more to reduce the second phase pinning center to the optimum 1–10 nm size at which critical current densities of 103–104 A/mm2 are obtained. Here we describe a powder metallurgy process that yields 6020 A/mm2 at 2 T and 1470 A/mm2 at 5 T for an alloy with an upper critical field of ∼8 T within the same strain space (∼13) employed in the conventional Nb-Ti fabrication process.

Electronic Resource

0011-2240

Elsevier Journal Backfiles on ScienceDirect 1907 - 2002

Biology

Medicine

Electronic Resource

0011-2240

Elsevier Journal Backfiles on ScienceDirect 1907 - 2002

Biology

Medicine

Electronic Resource

0005-2744

Elsevier Journal Backfiles on ScienceDirect 1907 - 2002

Biology

Electronic Resource

0011-2240

Elsevier Journal Backfiles on ScienceDirect 1907 - 2002

Biology

Medicine

Electronic Resource

1432-2277

Key words Small bowel transplantation ; Chronic rejection

Springer Online Journal Archives 1860-2000

Medicine

Abstract Our aim was to develop a model of chronic rejection (CR) in small bowel allografts, and to study the changes occurring in these grafts. Small bowel transplantation was performed using the DA to AS rat strain combination. Short-term (5 mg/kg intramuscular, from days − 2 to + 9), or long-term cyclosporin treatment (5 mg/kg, 3 times a week until day 50) was given to prevent acute rejection. Controls were untreated allografts, DA isografts with and without cyclosporin, and normal DA and AS rats. They were followed for 50 and 100 days after transplantation. Recipients of a syngeneic graft lost weight during the first week after transplantation, but started to regain weight and kept growing thereafter. Histology showed normal bowel architecture with normal mesenteric lymph nodes and Peyers patches. Vigorous acute rejection occurred in the untreated allografts. Animals had persistent weight loss, and were killed between 6–13 days after transplantation. No clinical signs of graft-versus-host disease were seen. Histology showed end-stage acute rejection. In both cyclosporin-treated allografted groups the postoperative course was as in the isografted animals. However, all animals had histologic signs of CR by 50 and 100 days after transplantation. Changes were most prominent in the mesentery. Serositis with increased vascularity, inflammation with sclerosis, and patchy myointimal proliferation with endothelialitis of the mesenteric vessels were found. Changes in the bowel were patchy and included some thickening of the muscle coat, crypt hyperplasia, scattered necrotic cells in the crypts, slight blunting of villi and loss of goblet cells. Infiltrating cells in the mesentery and bowel consisted mainly of CD 4+ cells, CD 8+ T-cells and monocytes/macrophages. Lactulose-mannitol urinary excretion ratio was significantly increased in short-term cyclosporin treated allografts at days 50 and 100 posttransplant. Serum albumin levels were significantly lowered in this group at both time points examined. We developed two models in which CR occurs after small bowel transplantation. Long-term cyclosporin treatment delayed the development of CR, since functional abnormalities were only seen in the animals that were treated with short-term cyclosporin.

Electronic Resource

1432-0878

Calmodulin ; Actin ; Photoreceptor membrane ; Microvilli ; Cytoskeleton ; Phototransduction ; Calcium ions ; Arthropods ; Squid

Springer Online Journal Archives 1860-2000

Biology

Medicine

Summary A monoclonal antibody against pea-leaf calmodulin was used to localise this calcium-binding protein on frozen sections of compound eyes of several arthropod species and on nitrocellulose replicas of electrophoretically separated peptides of isolated photoreceptor membrane from crayfish, fly, and squid. We report the presence of immunochemically detectable amounts of calmodulin specifically associated with the photoreceptor microvilli of rhabdomeral photoreceptors. A weak immunofluorescent signal was also observed in the cytoplasm of retinula cells. The presence of calmodulin in rhabdomeral microvilli is discussed in view of its possible implication in phototransduction and/or involvement in cytoskeletal structures associated with photoreceptor membranes in invertebrates.

Electronic Resource