Nanoscale magnetic field mapping with a single spin scanning probe magnetometer

We demonstrate quantitative magnetic field mapping with nanoscale resolution, by applying a lock-in technique on the electron spin resonance frequency of a single nitrogen-vacancy defect placed at the apex of an atomic force microscope tip. In addition, we report an all-optical magnetic imaging technique which is sensitive to large off-axis magnetic fields, thus extending the operation range of diamond-based magnetometry. Both techniques are illustrated by using a magnetic hard disk as a test sample. Owing to the non-perturbing and quantitative nature of the magnetic probe, this work should open up numerous perspectives in nanomagnetism and spintronics

Entwicklung eines kombinierten Nahfeldmikroskopie- und -spektroskopiesystems Bericht ueber das BMBF-Vorhaben 13N7643/6

Available from TIB Hannover: RO5065(47) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

Expression of Protein Kinase C isoforms and interleukin-1beta in myofibrillar myopathy

BACKGROUND: The term myofibrillar myopathy refers to a rare and clinically heterogeneous group of muscle disorders. The pathogenesis of this myopathy is not well understood. The morphologic hallmark is myofibrillar destruction with abnormal expression of numerous proteins, most consistently of desmin. METHODS: The authors investigated eight patients with myofibrillar myopathy belonging to four families. They studied the role of different protein kinase C isoforms and of interleukin-1beta, a cytokine that might activate protein kinase C and, in addition, mediate myofibrillar proteolysis. RESULTS: Immunohistochemical analysis showed the expression of alpha, eta, and zeta isoforms of protein kinase C and of interleukin-1beta in abnormal muscle fibers. Immunoblots confirmed the immunohistochemical data and revealed the absence of protein kinase C delta and epsilon in muscle fibers from patients and controls. CONCLUSIONS: These data suggest that protein kinase C and interleukin-1beta may play a role in the pathogenesis of myofibrillar myopathy

Substrate reconstruction and electronic surface states: Ag(001)

We present the result of a combined ab initio theoretical study and ultraviolet photoemission spectroscopy experiment of the electronic surface states of the clean and of the oxygen covered, unreconstructed and missing-row reconstructed, Ag(001) surface. For the clean and for the unreconstructed oxygen covered surface, theory and experiment find an electronic surface state at about 0.4 eV below the Fermi energy (EF) at the B point of the surface Brillouin zone. At the same point, theory predicts the existence of an empty state at +3 eV. Upon reconstruction, the photoemission signal of the filled state is strongly reduced and, according to calculations, the state shifts in energy above EF The surface interband transition (SIT) between the two states exists thus only for the unreconstructed surfaces and nearly matches the surface plasmon energy. Our investigation confirms therefore the correlation between the presence of this SIT and the anomaly of the surface plasmon dispersion curve of unreconstructed Ag(001). (C) 2001 Elsevier Science B.V. All rights reserved

Silicon nanostructures for photonics and photovoltaics

Silicon has long been established as the material of choice for the microelectronics industry. This is not yet true in photonics, where the limited degrees of freedom in material design combined with the indirect bandgap are a major constraint. Recent developments, especially those enabled by nanoscale engineering of the electronic and photonic properties, are starting to change the picture, and some silicon nanostructures now approach or even exceed the performance of equivalent direct-bandgap materials. Focusing on two application areas, namely communications and photovoltaics, we review recent progress in silicon nanocrystals, nanowires and photonic crystals as key examples of functional nanostructures. We assess the state of the art in each field and highlight the challenges that need to be overcome to make silicon a truly high-performing photonic material

Co-expression network analysis reveals transcription factors associated to cell wall biosynthesis in sugarcane

Sugarcane is a hybrid of Saccharum officinarum and Saccharum spontaneum, with minor contributions from other species in Saccharum and other genera. Understanding the molecular basis of cell wall metabolism in sugarcane may allow for rational changes in fiber quality and content when designing new energy crops. This work describes a comparative expression profiling of sugarcane ancestral genotypes: S. officinarum, S. spontaneum and S. robustum and a commercial hybrid: RB867515, linking gene expression to phenotypes to identify genes for sugarcane improvement. Oligoarray experiments of leaves, immature and intermediate internodes, detected 12,621 sense and 995 antisense transcripts. Amino acid metabolism was particularly evident among pathways showing natural antisense transcripts expression. For all tissues sampled, expression analysis revealed 831, 674 and 648 differentially expressed genes in S. officinarum, S. robustum and S. spontaneum, respectively, using RB867515 as reference. Expression of sugar transporters might explain sucrose differences among genotypes, but an unexpected differential expression of histones were also identified between high and low Brix° genotypes. Lignin biosynthetic genes and bioenergetics-related genes were up-regulated in the high lignin genotype, suggesting that these genes are important for S. spontaneum to allocate carbon to lignin, while S. officinarum allocates it to sucrose storage. Co-expression network analysis identified 18 transcription factors possibly related to cell wall biosynthesis while in silico analysis detected cis-elements involved in cell wall biosynthesis in their promoters. Our results provide information to elucidate regulatory networks underlying traits of interest that will allow the improvement of sugarcane for biofuel and chemicals production