Aging, osteoarthritis and transforming growth factor-beta signaling in cartilage.

Osteoarthritis is a common malady of the musculoskeletal system affecting the articular cartilage. The increased frequency of osteoarthritis with aging indicates the complex etiology of this disease, which includes pathophysiology and joint stability including biomechanics. The balance between anabolic morphogens and growth factors and catabolic cytokines is at the crux of the problem of osteoarthritis. One such signal is transforming growth factor-beta (TGF-beta). The impaired TGF-beta signaling has been identified as a culprit in old mice in a recent article in this journal. This commentary places this discovery in the context of anabolic and catabolic signals and articular cartilage homeostasis in the joint

Analysis of melt-textured YBCO with nanoscale inclusions

Recently, particles with the chemical composition Y2Ba 4CuMOx where M U, Nb, Zr, etc., and sizes in the range of 50 - 200 nm have been generated within the YBCO matrix of bulk, melt-processed superconductors in order to serve as effective flux pinning sites. By means of AFM and electron backscatter diffraction (EBSD) measurements, we analyse the spatial distribution and the size distribution of these nanoparticles within the superconducting YBCO matrix

Nano-composite single grain YBa2Cu3O 7-δ/Y2Ba4CuBiOy bulk superconductors

We have succeeded recently in synthesizing a chemically stable, inert family of materials of composition Y2Ba4CuMOy (Y-2411 where M Nb, Ta, Mo, W, Zr, Hf) within the superconducting YBa 2Cu3O7-δ (Y-123) phase matrix that forms effective flux pinning centers of nano-scale dimensions. In this paper we report the synthesis of the Y2Ba4CuBiOy phase with nano-scale dimensions that is similarly compatible with the Y-123 matrix and which does not impair the properties of the bulk superconductor. YBa 2Cu3O7-δ/Y2BaCuO5 (Y-123/Y-211) precursor powders enriched with various amounts of Bi 2O3 and Y2Ba4CuBiOy have been fabricated successfully in the form of large, single grains by the top seeded melt growth (TSMG) process. Microstructural studies of these composites reveal the presence of nanometer-sized Y2Ba4CuBiO y and much larger Y-211 phase particles (∼1 νm) embedded in the Y-123 phase matrix. The critical current density of the nano-composites is observed to increase significantly compared to undoped YBCO. © 2006 IOP Publishing Ltd

EBSD characterisation of Y2Ba4CuUOx phase in melttextured YBCO with addition of depleted uranium oxide

Melt-textured YBCO samples processed with added Y2O3 and depleted uranium oxide (DU) contain nano-particles, which have been identified previously as Y2Ba4CuUOx (U-411). This phase has a cubic unit cell, which is clearly distinct from the orthorhombic Y-123 and Y-211 phases within the YBCO system. In samples with a high amount of DU addition (0.8 wt-% DU), U-2411 particles have sizes between 200 nm and several νm, so identification of the Kikuchi patterns of this phase becomes possible. Together with a parallel EDX analysis, the particles embedded in the Y-123 matrix can be identified unambiguously. In this way, a three-phase EBSD scan becomes possible, allowing also the identification of nanometre-sized particles in the sample microstructure

Investigation of grain orientations of melt-textured HTSC with addition of uranium oxide, Y2O3 and Y2BaCuO5

Local grain orientations were studied in melt-textured YBCO samples processed with various amounts of depleted uranuim oxide (DU) and Y 2O3 by means of electron backscatter diffraction (EBSD) analysis. The addition of DU leads to the formation of Ucontaining nanoparticles (Y2Ba4CuUOx) with sizes of around 200 nm, embedded in the superconducting Y-123 matrix. The orientation of the Y 2BaCuO5 (Y-211) particles, which are also present in the YBCO bulk microstructure, is generally random as is the case in other melttextured Y-123 samples. The presence of Y-211 particles, however, also affects the orientation of the Y-123 matrix in these samples

Human stem cells and articular cartilage regeneration.

The regeneration of articular cartilage damaged due to trauma and posttraumatic osteoarthritis is an unmet medical need. Current approaches to regeneration and tissue engineering of articular cartilage include the use of chondrocytes, stem cells, scaffolds and signals, including morphogens and growth factors. Stem cells, as a source of cells for articular cartilage regeneration, are a critical factor for articular cartilage regeneration. This is because articular cartilage tissue has a low cell turnover and does not heal spontaneously. Adult stem cells have been isolated from various tissues, such as bone marrow, adipose, synovial tissue, muscle and periosteum. Signals of the transforming growth factor beta superfamily play critical roles in chondrogenesis. However, adult stem cells derived from various tissues tend to differ in their chondrogenic potential. Pluripotent stem cells have unlimited proliferative capacity compared to adult stem cells. Chondrogenesis from embryonic stem (ES) cells has been studied for more than a decade. However, establishment of ES cells requires embryos and leads to ethical issues for clinical applications. Induced pluripotent stem (iPS) cells are generated by cellular reprogramming of adult cells by transcription factors. Although iPS cells have chondrogenic potential, optimization, generation and differentiation toward articular chondrocytes are currently under intense investigation

Coherent Communication with Continuous Quantum Variables

The coherent bit (cobit) channel is a resource intermediate between classical and quantum communication. It produces coherent versions of teleportation and superdense coding. We extend the cobit channel to continuous variables by providing a definition of the coherent nat (conat) channel. We construct several coherent protocols that use both a position-quadrature and a momentum-quadrature conat channel with finite squeezing. Finally, we show that the quality of squeezing diminishes through successive compositions of coherent teleportation and superdense coding.Comment: 4 pages, 3 figure