Analysis of Magnetization Reversal Process of Nd-Fe-B Sintered Magnets by Magnetic Domain Observation Using Kerr Microscope

We used a Kerr microscope, image processing, and photo editing to clarify magnetization reversal and its propagation in a sintered Nd-Fe-B magnet. Magnetic domain change was observed when a dc field from +20 to 20 kOe was applied to a sintered Nd-Fe-B magnet. Simultaneous magnetization reversal in several grains along the easy axis direction and its propagation to neighboring grains occurred. This indicates that the nucleation field in a grain and magnetic interaction between grains are important controlling factors of the coercivity of sintered Nd-Fe-B magnets

Domain Wall Pinning by Step-Like Thickness Change in Magnetic Thin Film

A thin-film element with a steplike thickness change has been fabricated to investigate experimentally a pinning effect of domain walls by a shape control of thin-film devices. Using a Kerr microscope, domain observation has been done to measure pinning characteristics of the element. It has been shown that 40% steplike thickness change of the film thickness can realize a wall pinning, and a pinning field of 2.53 Oe is obtained. The pinning field increases with increasing steplike thickness change ratio

Regulated Expression of a Calmodulin Isoform Alters Growth and Development in Potato

A transgene approach was taken to study the consequences of altered expression of a calmodutin iso-form on plant growth and development. Eight genomic clones of potato calmodulin (PCM 1 to 8) have been isolated and characterized. Among the potato calmodulin isoforms studied, PCM 1 differs from the other isoforms because of its unique amino acid substitutions. Transgenic potato plants were produced carrying sense construct of PCM 1 fused to the CAMV 35S promoter. Transgenic plants showing a moderate increase in PCM 1 MRNA exhibited strong apical dominance, produced elongated tubers, and were taller than the controls. Interestingly, the plants expressing the highest level of PCM 1 MRNA did not form underground tubers. Instead, these transgenic plants produced aerial tubers when allowed to grow for longer periods. The expression of different calmodulin isoforms (PCM 1, 5, 6, and 8) was studied in transgenic plants. Among the four potato calmodulin isoforms, only the expression of PCM 1 MRNA was altered in transgenic plants, while the expression of other isoforms was not significantly altered. Western analysis revealed increased PCM 1 protein in transgenic plants, indicating that the expression of both MRNA and protein are altered in transgenic plants. These results suggest that increasing the expression of PCM 1 alters growth and development in potato plants

Magnetic domain observation of hydrogenation disproportionation desorption recombination processed Nd－Fe－B powder with a high-resolution Kerr microscope using ultraviolet light

A Kerr microscope that uses ultraviolet (UV) light for high-resolution domain observation was built, and the domain structure and magnetization process of hydrogenation disproportionation desorption recombination (HDDR) powder were examined. The UV Kerr microscope could observe nanometer-sized domain patterns. Applying a dc field of 1.0 kOe to HDDR powder at a desorption recombination (DR) time of 12 min produced abrupt wall motion. The pinning force exerted by the grain boundaries is inadequate for producing high coercivity because the Nd-rich phase layers along these boundaries are absent at a DR time of 12 min. For HDDR powder at a DR time greater than 14 min, changing the magnetic field by up to 1.0 kOe produced no observable wall motion. It follows that the high coercivity of HDDR powder is due to domain wall pinning at the grain boundaries

Domain Observation of Amorphous Wire with Large Diameter for Micro-Sensor and Micro-Motor Application

Domain structures of Fe-Si-B-Nb amorphous wires with a large diameter were investigated. A 10% increase of pulse output voltage due to large Barkhausen jumps in the Fe-Si-B-Nb wire at the diameter of 200 μm has been obtained which is less than expected due to decreased saturation and small domain size. Domain observation results indicate that the increase of the domain size in the inner core of the wire is important for high sensor output

London equation studies of thin-film superconductors with a triangular antidot lattice

We report on a study of vortex pinning in nanoscale antidot defect arrays in the context of the London Theory. Using a wire network model, we discretize the array with a fine mesh, thereby providing a detailed treatment of pinning phenomena. The use of a fine grid has enabled us to examine both circular and elongated defects, patterned in the form of a rhombus. The latter display pinning characteristics superior to circular defects constructed with the similar area. We calculate pinning potentials for defects containing zero and single quanta, and we obtain a pinning phase diagram for the second matching field, $H = 2 \Phi_{o}$.Comment: 10 pages and 14 figure

The Photoreceptor Cell-Specific Nuclear Receptor Gene (PNR ) Accounts for Retinitis Pigmentosa in the Crypto-Jews from Portugal (Marranos), Survivors from the Spanish Inquisition

The last Crypto-Jews (Marranos) are the survivors of Spanish Jews who were persecuted in the late fifteenth century, escaped to Portugal and were forced to convert to save their lives. Isolated groups still exist in mountainous areas such as Belmonte in the Beira-Baixa province of Portugal. We report here the genetic study of a highly consanguineous endogamic population of Crypto-Jews of Belmonte affected with autosomal recessive retinitis pigmentosa (RP). A genome-wide search for homozygosity allowed us to localize the disease gene to chromosome 15q22-q24 (Zmax=2.95 at θ=0 at the D15S131 locus). Interestingly, the photoreceptor cell-specific nuclear receptor (PNR) gene, the expression of which is restricted to the outer nuclear layer of retinal photoreceptor cells, was found to map to the YAC contig encompassing the disease locus. A search for mutations allowed us to ascribe the RP of Crypto-Jews of Belmonte to a homozygous missense mutation in the PNR gene. Preliminary haplotype studies support the view that this mutation is relatively ancient but probably occurred after the population settled in Belmonte

At-home blood collection and stabilization in high temperature climates using home RNA

Expanding whole blood sample collection for transcriptome analysis beyond traditional phlebotomy clinics will open new frontiers for remote immune research and telemedicine. Determining the stability of RNA in blood samples exposed to high ambient temperatures (\u3e30°C) is necessary for deploying home-sampling in settings with elevated temperatures (e.g., studying physiological response to natural disasters that occur in warm locations or in the summer). Recently, we have develope