Distribution of halogens in an Antarctic ordinary chondrite, Y-74014 (H6)

One of the striking features in Antarctic meteorites is overabundances of halogens, especially iodine. In order to investigate how these halogens are distributed in constituent mineral phases of Antarctic chondrites, the outer portion of Yamato (Y)-74014 H6 chondrite (Y-74014,101) was subjected to fractional dissolution using several solutions with different chemical properties. Pulverized meteorite sample was successively leached by acetone, (hot) water, EDTA and nitric acid, and individual leachates as well as the acid residue were analyzed for halogens by neutron activation analysis. About 10% of iodine was recovered in acetone whereas only less than 2% of Cl and Br are leached, suggesting that overabundant iodine is partly present in the form of acetone-soluble, possibly organic compound. Dissolution patterns of Cl and I with water are similar to each other. This implies that contaminated Cl and I both reside in a common phase, presumably in akaganeite, a corrosion product of Fe-Ni alloy with chlorine attracted from the environment. Either iodine was involved in this mineral when corrosion reaction occurred or iodine was later migrated into the mineral by exchanging with Cl^- and/or OH^-. For the chronological studies using long-lived nuclides such as ^Cl and ^I, it is essential to use indigenous halogens in meteorites. For such purposes, the acid-residual fraction can be used even for Antarctic meteorites having overabundant halogens. In addition, Cl, Br and I contents in bulk Allende and Bruderheim chondrites are also obtained in this study and their abundances are briefly discussed

Composite THz materials using aligned metallic and semiconductor microwires, experiments and interpretation

We report fabrication method and THz characterization of composite films containing either aligned metallic (tin alloy) microwires or chalcogenide As2Se3 microwires. The microwire arrays are made by stack-and-draw fiber fabrication technique using multi-step co-drawing of low-melting-temperature metals or semiconductor glasses together with polymers. Fibers are then stacked together and pressed into composite films. Transmission through metamaterial films is studied in the whole THz range (0.1-20 THz) using a combination of FTIR and TDS. Metal containing metamaterials are found to have strong polarizing properties, while semiconductor containing materials are polarization independent and could have a designable high refractive index. Using the transfer matrix theory, we show how to retrieve the complex polarization dependent refractive index of the composite films. We then detail the selfconsistent algorithm for retrieving the optical properties of the metal alloy used in the fabrication of the metamaterial layers by using an effective medium approximation. Finally, we study challenges in fabrication of metamaterials with sub-micrometer metallic wires by repeated stack-and-draw process by comparing samples made using 2, 3 and 4 consecutive drawings. When using metallic alloys we observe phase separation effects and nano-grids formation on small metallic wires

Radiocarbon in 9th to 5th Century BC Tree-Ring Samples from the Ouban 1 Archaeological Site, Hiroshima, Japan

From the 19th International Radiocarbon Conference held in Keble College, Oxford, England, April 3-7, 2006.In order to investigate the regional atmospheric radiocarbon offset, accelerator mass spectrometry (AMS) 14C measurements were made on 5-yr increments of a Japanese wood sample dendrochronologically dated to 820-436 BC. The 14C data from the Japanese tree-ring samples were compared with the IntCal04 calibration curve (Reimer et al. 2004). In most parts, the differences between IntCal04 and 14C dates in the Japanese tree-ring samples were within experimental statistical errors. At around 680 BC, however, significant differences of up to 100 14C yr were observed. These differences may indicate either regional offsets in Japan or the short-term fluctuation of a subdecadal timescale in atmospheric 14C variations.The Radiocarbon archives are made available by Radiocarbon and the University of Arizona Libraries. Contact [email protected] for further information.Migrated from OJS platform February 202

Radiocarbon in 9th to 5th Century BC Tree-Ring Samples from the Ouban 1 Archaeological Site, Hiroshima, Japan

From the 19th International Radiocarbon Conference held in Keble College, Oxford, England, April 3-7, 2006.In order to investigate the regional atmospheric radiocarbon offset, accelerator mass spectrometry (AMS) 14C measurements were made on 5-yr increments of a Japanese wood sample dendrochronologically dated to 820-436 BC. The 14C data from the Japanese tree-ring samples were compared with the IntCal04 calibration curve (Reimer et al. 2004). In most parts, the differences between IntCal04 and 14C dates in the Japanese tree-ring samples were within experimental statistical errors. At around 680 BC, however, significant differences of up to 100 14C yr were observed. These differences may indicate either regional offsets in Japan or the short-term fluctuation of a subdecadal timescale in atmospheric 14C variations.The Radiocarbon archives are made available by Radiocarbon and the University of Arizona Libraries. Contact [email protected] for further information.Migrated from OJS platform February 202

Radiocarbon Wiggle-Matching of Japanese Historical Materials with a Possible Systematic Age Offset

From the 19th International Radiocarbon Conference held in Keble College, Oxford, England, April 3-7, 2006.Progress in radiocarbon accelerator mass spectrometry (AMS) techniques enables much more access to wiggle-matching techniques for high-precision 14C dating with relatively low costs than before. Recently, we have applied wiggle-matching for a number of wood samples where dendrochronology is difficult because of various limitations imposed for dendro-dating. In most cases, wiggle-matching gave rather unambiguous calendar ages, but we found that in some cases the calibrated date was very sensitive to a systematic error of the 14C date. Here, we present a wooden artifact from the Ujishigai archaeological site as a case where the highest wiggle-matched date did not agree with the date given by dendrochronology. An age with lower probability agreed with the tree-ring age of AD 389, which marked the beginning of the production of Sue ware (unglazed stoneware) in Japan. We show that systematic errors must be carefully taken into account while interpreting 14C wiggle-matching results, whether they are due to instrumental errors (statistical) or due to a regional offset from the IntCal04 (Reimer et al. 2004) calibration curve.The Radiocarbon archives are made available by Radiocarbon and the University of Arizona Libraries. Contact [email protected] for further information.Migrated from OJS platform February 202

Radiocarbon Wiggle-Matching of Japanese Historical Materials with a Possible Systematic Age Offset

From the 19th International Radiocarbon Conference held in Keble College, Oxford, England, April 3-7, 2006.Progress in radiocarbon accelerator mass spectrometry (AMS) techniques enables much more access to wiggle-matching techniques for high-precision 14C dating with relatively low costs than before. Recently, we have applied wiggle-matching for a number of wood samples where dendrochronology is difficult because of various limitations imposed for dendro-dating. In most cases, wiggle-matching gave rather unambiguous calendar ages, but we found that in some cases the calibrated date was very sensitive to a systematic error of the 14C date. Here, we present a wooden artifact from the Ujishigai archaeological site as a case where the highest wiggle-matched date did not agree with the date given by dendrochronology. An age with lower probability agreed with the tree-ring age of AD 389, which marked the beginning of the production of Sue ware (unglazed stoneware) in Japan. We show that systematic errors must be carefully taken into account while interpreting 14C wiggle-matching results, whether they are due to instrumental errors (statistical) or due to a regional offset from the IntCal04 (Reimer et al. 2004) calibration curve.The Radiocarbon archives are made available by Radiocarbon and the University of Arizona Libraries. Contact [email protected] for further information.Migrated from OJS platform February 202

Oral Rehabilitation of Oral Cancer Patients Using Zygomatic Implant-Supported Maxillary Prostheses with Magnetic Attachment: Three Case Reports

Maxillectomy for malignant tumor often results in a maxillary defect and serious oral dysfunction. A prosthesis is usually provided for postoperative oral rehabilitation of such patients with maxillary defects. However, the further the resected region extends, the less stable the prosthesis becomes, due to insufficient bone and tooth support. Therefore, in many cases, conventional resection dentures may not be adequate to restore the oral function. Effective utilization of dental and zygomatic implants may help to restore oral function in patients with severe maxillary defects. This clinical report describes the management of three patients with severe maxillary defects following cancer ablative surgery who were rehabilitated using maxillary prostheses with magnetic attachments supported by dental and zygomatic implants. Occlusal reconstruction was performed with removable prostheses supported with two or four implants and magnetic attachment. The oral function was evaluated before and after prosthodontic treatment with implants using the Oral Health Impact Profile (OHIP-14) and functional chewing score. Results indicated improvement in all cases. These findings show that quality of life (QOL) and oral function were improved

Aging of wood: Analysis of color changes during natural aging and heat treatment

The color properties of aging wood samples from historical buildings have been compared with those of recent wood samples that were heat treated at temperatures ranging from 90℃ to 180℃. The results of kinetic analysis obtained by the time-temperature superposition method showed that the color change during natural aging was mainly due to a slow and mild oxidation process. In other words, heat treatment could accelerate the changes in wood color that occur during aging. In one sample, the color change (ΔE*ab) after 921 years at ambient temperature was almost equivalent to that of heating (artificial aging) approximately for 6.7 h at 180℃. The results have been interpreted that the aging and the subsequent change in wood color begin at the time of tree harvesting