Laser-induced fine structures on silicon exposed to THz-FEL

We found the irradiation of focused linearly polarized terahertz (THz)-waves emitted from THz free-electron laser (THz-FEL) engraved fine periodic stripe structures on the surfaces of single-crystal Si wafers. The experiments were performed at several wavelengths ranging from 50 to 82 μm with a macro-pulse fluence up to 32 J/cm2. The engraved structures are considered equivalent to the laser-induced periodic surface structures (LIPSS) produced by the irradiation of a femtosecond (fs)-pulsed laser in the near-infrared (NIR) region. However, the minimum period of ∼1/25 of the wavelength in the present case of THz-FEL is surely much smaller than those reported so far by use of fs-lasers and no more explicable by the so far proposed mechanisms. The finer LIPSS confirmed by longer-wavelength laser excitation by means of THz-FEL motivates investigation into the universal mechanism of LIPSS formation, which has been under a hot debate for decades

ワムシの生殖に与える光波長の影響

The monogonont rotifer Brachionus manjavacas (Australian strain) showed a steadily increasing population growth and larger number of resting egg production under continuous white light compared to under total darkness when they were batch cultured. By comparing different wavelength of light, such as white (control), 470 (blue), 525 (green) and 660 (red) nm, rotifers showed no significant differences in specific population growth rate, but sexual reproduction showed different patterns associated with light wavelengths. Although there were no significant differences with regard to mixis induction, the resting egg formation actively occurred at 525 nm. We further observed the movement of female rotifers to find the influential factor of different sexual reproduction. There was no significant difference in the mean swimming speed of 10 female rotifers, but the proportion of settling individuals varied with light wavelength. Under 525 nm light, no individuals continuously settled for one minute, while under other light wavelengths the percent of settling females for a minute ranged between 6.1±5.4 and 23.8±6.5%. The higher ratio of swimming females at 525 nm should enhance the male/female encounters, which resulted in higher resting egg formation.シオミズツボワムシ複合種 Brachionus manjavacas （いわゆる L 型オーストラリア株、以下ワムシと略）を Tetraselmis 給餌によってバッチ培養したところ、暗黒下での培養よりも白色光の連続照射下で活発な個体群増殖と耐久卵形成を示した。次に、青 (470 nm)、緑 (525 nm)、赤 (660 nm)および白色光 (対照) の連続光照射下（約 1.4 W/m2）で培養し、個体群増殖率（r）、両性生殖誘導率、受精率、耐久卵数を求めた。異なる波長光の照射によってワムシの個体群増殖率と両性生殖誘導率に変化はなかったが、耐久卵形成は光波長 525 nm のとき最も活発に起こった。雌ワムシの遊泳速度は照射光波長にかかわらず一定だったが、付着行動を示す雌ワムシは光波長 660 nm のとき最も多くなった。一方、光波長 525 nm では付着個体が出現せず、全個体が遊泳した。光波長 525 nm のとき、雌ワムシの活発な遊泳行動によって、雄ワムシとの接触頻度が増大し、受精と耐久卵形成が促進された可能性がある

Iodide-Mediated or Iodide-Catalyzed Demethylation and Friedel-Crafts C-H Borylative Cyclization Leading to Thiophene-Fused 1,2-Oxaborine Derivatives

The first synthesis of dithieno-1,2-oxaborine derivatives was achieved via iodide-mediated or iodide-catalyzed demethylation of 3-methoxy-2,2'-bithiophene and subsequent C-H borylation. A wide variety of thiophene-fused oxaborines could be synthesized by the procedure

Isolation of mixis-related genes from the rotifer Brachionus plicatilis using subtractive hybridization

The monogonont rotifer Brachionus plicatilis produces resting eggs through sexual reproduction (mixis), which is affected by external and internal factors. We collected resting eggs from rotifers cultured at 15 and 25°C and hatched them with and without 14-day dormancy in the dark. Stem females hatched from both conditions were further cultured at 15, 20 and 25°C. We obtained two phenotypes, one with high mixis (more than 50%), which was hatched from resting eggs formed at 15°C without dormancy, and another in which sexual reproduction occurred at 25°C and resting eggs were formed at 15°C with a 14-day dormancy. In the latter phenotype, mictic females appeared at 15°C, but not at 25°C. Using subtractive hybridization, we isolated one gene from the latter phenotype of females that had no significant similarity to known genes in BLAST searches. We propose that this gene is unique to rotifer mictic reproduction. Ongoing characterization of this gene attempts understand its role in mixis.The original publication is available at www.springerlink.co

Registration and Summation of Respiratory-Gated or Breath-Hold PET Images Based on Deformation Estimation of Lung from CT Image

Lung motion due to respiration causes image degradation in medical imaging, especially in nuclear medicine which requires long acquisition times. We have developed a method for image correction between the respiratory-gated (RG) PET images in different respiration phases or breath-hold (BH) PET images in an inconsistent respiration phase. In the method, the RG or BH-PET images in different respiration phases are deformed under two criteria: similarity of the image intensity distribution and smoothness of the estimated motion vector field (MVF). However, only these criteria may cause unnatural motion estimation of lung. In this paper, assuming the use of a PET-CT scanner, we add another criterion that is the similarity for the motion direction estimated from inhalation and exhalation CT images. The proposed method was first applied to a numerical phantom XCAT with tumors and then applied to BH-PET image data for seven patients. The resultant tumor contrasts and the estimated motion vector fields were compared with those obtained by our previous method. Through those experiments we confirmed that the proposed method can provide an improved and more stable image quality for both RG and BH-PET images

Synthesis and Properties of Dithieno-Fused 1,4-Azaborine Derivatives.

The first synthesis of dithieno[3,2- b:2',3'- e][1,4]azaborinine (DTAB) derivatives has been achieved by Buchwald-Hartwig coupling and subsequent Friedel-Crafts-type C-H borylation. A facile method for further π-extension of DTAB was also developed via stannylation and subsequent Kosugi-Migita-Stille cross-coupling reaction. The fundamental properties of DTAB derivatives were also investigated

Itinerant U 5f band states in the layered compound UFeGa5 observed by soft X-ray angle-resolved photoemission spectroscopy

We have performed angle-resolved photoemission spectroscopy (ARPES) experiments on paramagnetic UFeGa5 using soft X-ray synchrotron radiation (hn=500eV) and derived the bulk- and U 5f-sensitive electronic structure of UFeGa5. Although the agreement between the experimental band structure and the LDA calculation treating U 5f electrons as being itinerant is qualitative, the morphology of the Fermi surface is well explained by the calculation, suggesting that the U 5f states can be essentially understood within the itinerant-electron model.Comment: 13 pages, 4 figur

Spatially Resolved Spectral Imaging by A THz-FEL

Using the unique characteristics of the free-electron-laser (FEL), we successfully performed high-sensitivity spectral imaging of different materials in the terahertz (THz) and far-infrared (FIR) domain. THz imaging at various wavelengths was achieved using in situ spectroscopy by means of this wavelength tunable and monochromatic source. In particular, owing to its large intensity and directionality, we could collect high-sensitivity transmission imaging of extremely low-transparency materials and three-dimensional objects in the 3–6 THz range. By accurately identifying the intrinsic absorption wavelength of organic and inorganic materials, we succeeded in the mapping of spatial distribution of individual components. This simple imaging technique using a focusing optics and a raster scan modality has made it possible to set up and carry out fast spectral imaging experiments on different materials in this radiation facility