Dielectric and Vibrational Properties of La3+ Substituted Relaxor (Na1/2Bi1/2)TiO3 Ceramics

N. Zhong,A. Hushur,G. Shabbir,S. Kojima 한국물리학회 2005 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.46 No.1

Dierent concentrations of A-site substitute La3+ were selected to modify (Na1=2Bi1=2)TiO3 ceramics. Dielectric permittivity and dissipation factor (tan ) of Na1=2Bi1=2xLax)TiO3 (x = 0.5%, 1 %, 5 % and 10 %) were measured at room temperature. Raman scattering was performed on all components at room temperature. From the dielectric measurement, we can conclude that both permittivity and tan markedly depend on frequency. At low frequency, permittivity and tan varied, and increased with La3+ concentration. However, in comparison with those at low frequency, permittivity and tan changed little at high frequency. The Raman spectra show that all bands are relatively broad, which is mainly due to the disorder on the A-site ions of perovskite structure. The bands around 130 cm1 and 270 cm1 were selected to analyzed, since they are well separated from others. With an increase of La3+ concentration, the band around 130 cm1 showed nearly no shift, while the band around 270 cm1 shifted to lower frequency.

Pathogenesis and Bone Resorption in Acquired Cholesteatoma: Current Knowledge and Future Prospectives

Mahmood A. Hamed,Seiichi Nakata,Ramadan H. Sayed,Hiromi Ueda,Badawy S. Badawy,Yoichi Nishimura,Takuro Kojima,Noboru Iwata,Ahmed R. Ahmed,Khalid Dahy,Naoki Kondo,Kenji Suzuki 대한이비인후과학회 2016 Clinical and Experimental Otorhinolaryngology Vol.9 No.4

Cholesteatoma is a cystic non tumorous lesion of the temporal bone that has the ability to destroy nearby structures by its power to cause bone resorption and as a result, fatal complications prevail. We aimed to conduct a comprehensive review for pathogenesis of acquired cholesteatoma, bone resorption mechanisms, and offer a future vision of this serious disease. We have reviewed different theories for pathogenesis of acquired cholesteatoma including the most relevant and updated ones with special emphasis on the mechanisms of bone resorption through Medline/PubMed research using the keywords ‘aetiopathogenesis, bone resorption, acquired cholesteatoma, temporal bone, and cytokines.’ In order to strengthen our study, we searched the reference lists of identified reviews. Cholesteatoma is a subject of debate among otolaryngologists since it was prescribed firstly. Over many decades, several theories were postulated for aetiopathogenesis of cholesteatoma with a tendency to follow more than one theory to explain the proper nature of that disease. Until now, the mechanism of bone resorption has yet to be more clarified. In the last century, a leap has occurred in the field of biomolecular cholesteatoma research which improved our knowledge about its pathophysiology and bone destructive mechanism. However, surgery is still the only available treatment. We conclude that discovery of new therapeutic choices for cholesteatoma other than surgery by the use of anti-growth, anti-proliferative, apoptotic agents as well as medications that antagonize osteoclastogenesis should be the main concern in the future clinical and experimental research work. Also, searching for predictors of the aggressiveness of cholesteatoma can affect the timing of intervention and prevent occurrence of complications.

Studies of aberrant phyllotaxy1 mutants of maize indicate complex interactions between auxin and cytokinin signaling in the shoot apical meristem.

Lee, Byeong-ha,Johnston, Robyn,Yang, Yan,Gallavotti, Andrea,Kojima, Mikiko,Travenç,olo, Bruno A N,Costa, Luciano da F,Sakakibara, Hitoshi,Jackson, David American Society of Plant Physiologists 2009 PLANT PHYSIOLOGY - Vol.150 No.1

<P>One of the most fascinating aspects of plant morphology is the regular geometric arrangement of leaves and flowers, called phyllotaxy. The shoot apical meristem (SAM) determines these patterns, which vary depending on species and developmental stage. Auxin acts as an instructive signal in leaf initiation, and its transport has been implicated in phyllotaxy regulation in Arabidopsis (Arabidopsis thaliana). Altered phyllotactic patterns are observed in a maize (Zea mays) mutant, aberrant phyllotaxy1 (abph1, also known as abphyl1), and ABPH1 encodes a cytokinin-inducible type A response regulator, suggesting that cytokinin signals are also involved in the mechanism by which phyllotactic patterns are established. Therefore, we investigated the interaction between auxin and cytokinin signaling in phyllotaxy. Treatment of maize shoots with a polar auxin transport inhibitor, 1-naphthylphthalamic acid, strongly reduced ABPH1 expression, suggesting that auxin or its polar transport is required for ABPH1 expression. Immunolocalization of the PINFORMED1 (PIN1) polar auxin transporter revealed that PIN1 expression marks leaf primordia in maize, similarly to Arabidopsis. Interestingly, maize PIN1 expression at the incipient leaf primordium was greatly reduced in abph1 mutants. Consistently, auxin levels were reduced in abph1, and the maize PIN1 homolog was induced not only by auxin but also by cytokinin treatments. Our results indicate distinct roles for ABPH1 as a negative regulator of SAM size and a positive regulator of PIN1 expression. These studies highlight a complex interaction between auxin and cytokinin signaling in the specification of phyllotactic patterns and suggest an alternative model for the generation of altered phyllotactic patterns in abph1 mutants. We propose that reduced auxin levels and PIN1 expression in abph1 mutant SAMs delay leaf initiation, contributing to the enlarged SAM and altered phyllotaxy of these mutants.</P>

Standardisation of defined approaches for skin sensitisation testing to support regulatory use and international adoption: position of the International Cooperation on Alternative Test Methods

Casati, S.,Aschberger, K.,Barroso, J.,Casey, W.,Delgado, I.,Kim, T. S.,Kleinstreuer, N.,Kojima, H.,Lee, J. K.,Lowit, A.,Park, H. K.,Ré,gimbald-Krnel, M. J.,Strickland, J.,Whelan, M.,Yang, Y.,Zua Springer Berlin Heidelberg 2018 Archives of toxicology Vol.92 No.2

<P>Skin sensitisation is the regulatory endpoint that has been at the centre of concerted efforts to replace animal testing in recent years, as demonstrated by the Organisation for Economic Co-operation and Development (OECD) adoption of five non-animal methods addressing mechanisms under the first three key events of the skin sensitisation adverse outcome pathway. Nevertheless, the currently adopted methods, when used in isolation, are not sufficient to fulfil regulatory requirements on the skin sensitisation potential and potency of chemicals comparable to that provided by the regulatory animal tests. For this reason, a number of defined approaches integrating data from these methods with other relevant information have been proposed and documented by the OECD. With the aim to further enhance regulatory consideration and adoption of defined approaches, the European Union Reference Laboratory for Alternatives to Animal testing in collaboration with the International Cooperation on Alternative Test Methods hosted, on 4–5 October 2016, a workshop on the international regulatory applicability and acceptance of alternative non-animal approaches, i.e., defined approaches, to skin sensitisation assessment of chemicals used in a variety of sectors. The workshop convened representatives from more than 20 regulatory authorities from the European Union, United States, Canada, Japan, South Korea, Brazil and China. There was a general consensus among the workshop participants that to maximise global regulatory acceptance of data generated with defined approaches, international harmonisation and standardisation are needed. Potential assessment criteria were defined for a systematic evaluation of existing defined approaches that would facilitate their translation into international standards, e.g., into a performance-based Test Guideline. Informed by the discussions at the workshop, the ICATM members propose practical ways to further promote the regulatory use and facilitate adoption of defined approaches for skin sensitisation assessments.</P>

Sound velocities and hypersonic dampings of Pb[(Mg_1/3Nb_2/3)_0.45Ti_0.55]O₃ single crystals studied by Brillouin light scattering

Ko, Jae-Hyeon,Kim, Tae Hyun,Kojima, Seiji,Bokov, Alexei A,Ye, Zuo-Guang IOP Pub 2010 Journal of Physics, Condensed Matter Vol.22 No.48

<P>A Brillouin spectroscopic investigation was carried out on PMN–55%PT single crystals, which are known to have no chemically ordered regions and undergo a well-defined structural phase transition at <I>T</I><SUB>C</SUB> ∼ 521 K. The longitudinal and transverse sound velocities probed on a right-angle scattering geometry exhibited a remarkable softening and increasing hypersonic damping on approaching <I>T</I><SUB>C</SUB> from <I>T</I><SUB>B</SUB> ∼ 610 K that was characterized by the deviation of the dielectric permittivity from the high-temperature Curie–Weiss behavior. The acoustic anomalies of the longitudinal acoustic mode at the backward scattering were more substantial than those observed at the right-angle scattering, which could be understood in the framework of normal acoustic dispersion considering the difference in the acoustic frequency. The softening of the transverse sound velocity was more significant than that of the longitudinal one upon cooling toward <I>T</I><SUB>C</SUB>, suggesting that this acoustic anomaly may be related to the local rhombohedral transformation, occurring in polar nano-regions (PNRs). The observed acoustic behaviors combined with the central peak dynamics clearly indicated the existence of dynamic polar nano-regions in PMN–55%PT where there are no chemically ordered regions, and seem to suggest that the order parameter fluctuations due to two kinds of coupling contribute to the acoustic anomalies in the temperature range of <I>T</I><SUB>C</SUB> ∼ <I>T</I><SUB>B</SUB>: electrostrictive coupling between the acoustic waves and the dynamic PNRs, and linear coupling between the acoustic waves and the precursor polar clusters, i.e., the ordering unit responsible for the order–disorder-type slowing down behavior probed by the central peak. </P>

A study on the Raman spectra of Al-doped and Ga-doped ZnO ceramics

장민수,류민기,이순현,김형국,A. Onodera,S. Kojima,윤명희 한국물리학회 2009 Current Applied Physics Vol.9 No.3

AlxZn1-xO and GayZn1-yO ceramics were synthesized through a solid-state reaction technique. The crystal phase of the samples was identified by an X-ray diffraction experiment. For each sample, the electrical resistivity was determined. The Al 2-mol%-doped and Ga 0.5-mol%-doped ZnO ceramics had the lowest resistivity. Raman measurement was performed to study the doping effects in the ZnO ceramics including ZnO single crystal as a reference. The line-shape parameters, q1 and C1, at the same certain doping rate and the solubility limit of Al (2 mol%) and Ga (0.5 mol%) in ZnO ceramics, are strongly related to the each other, and that the solubility limit plays an important role. The second-order Raman peak at 1162 cm-1 of the ZnO ceramics was fitted by Fano formalism. The Fano’s fitting parameters, such as the lifetime of phonon and the degree of asymmetry degree of the second-order Raman peak changed as the amounts of dopants were varied.

A study on the Raman spectra of Al-doped and Ga-doped ZnO ceramics

Jang, M.S.,Ryu, M.K.,Yoon, M.H.,Lee, S.H.,Kim, H.K.,Onodera, A.,Kojima, S. Elsevier 2009 Current Applied Physics Vol.9 No.3

Al<SUB>x</SUB>Zn<SUB>1-x</SUB>O and Ga<SUB>y</SUB>Zn<SUB>1-y</SUB>O ceramics were synthesized through a solid-state reaction technique. The crystal phase of the samples was identified by an X-ray diffraction experiment. For each sample, the electrical resistivity was determined. The Al 2-mol%-doped and Ga 0.5-mol%-doped ZnO ceramics had the lowest resistivity. Raman measurement was performed to study the doping effects in the ZnO ceramics including ZnO single crystal as a reference. The line-shape parameters, q<SUB>1</SUB> and Γ<SUB>1</SUB>, at the same certain doping rate and the solubility limit of Al (2mol%) and Ga (0.5mol%) in ZnO ceramics, are strongly related to the each other, and that the solubility limit plays an important role. The second-order Raman peak at 1162cm<SUP>-1</SUP> of the ZnO ceramics was fitted by Fano formalism. The Fano's fitting parameters, such as the lifetime of phonon and the degree of asymmetry degree of the second-order Raman peak changed as the amounts of dopants were varied.

γ-LA-Supplementation to IVC for IVP Bovine Embryos

Gaja, A.,Meng, C.L.,Sato, M.,Nakajima, T.,Kubota, Chikara,Kojima, T. Asian Australasian Association of Animal Productio 2010 Animal Bioscience Vol.23 No.1

The present study aimed to examine the effects of ${\gamma}$-linolenic acid (GLA) supplementation to in vitro culture (IVC) medium on in vitro developmental competence, freezability and morphology of in vitro matured and fertilized bovine embryos. In vitro produced (IVP) bovine zygotes were cultured in IVC medium supplemented with 0 (negative control), 15, 31, 62, 125, 250, 500 or 1,000 ppm GLA, 250 ppm linoleic acid albumin (LAA) and without any supplement as a control. Day 6 blastocysts derived from culture control were cultured in IVC medium containing either 62, 250 GLA or 250 LAA for 24 h, and at Day 7 were subjected to freezing or morphological examination by electron microscope. GLA 15 showed a tendency to have a higher cleavage rate at Day 2 (70.3%) than other groups. The hatching rate at Day 9 in LAA (38.2%) was significantly higher than the control and all treatment groups (p<0.05), while the blastocyst rate in LAA (32.4%) did not differ from those of 15 (30.5%), 31 (27.1%), and 62 GLA (33.1%) or the control (35.1%). GLA in concentrations of 125, 250, 500, and 1,000 ppm had significantly detrimental effect on the blastocyst rate compared to 15, 31 and 62 ppm GLA, LAA, and control groups (p<0.05). In contrast, the highest post-thaw survival rate (100%) was observed in the control group (p<0.01). Large lipid droplets were observed in the cytoplasm of trophoblastic cells, even in the control, but were abundant in GLA groups. Taking the results of the study into consideration, the addition of GLA to the culture medium for IVP bovine embryos at the dose of 15 ppm increased the developmental competence of zygotes and enhanced the cleavage rate up to Day 2. However, blastulation rate and post-thaw survival were not increased when GLA was added to the culture media.

Observations of the radial particle flux induced by the phase difference between density and potential fluctuations using a gold neutral beam probe in the tandem mirror GAMMA 10

atsushi Kojima,A. Itakura,H. Kakiuchi,H. Higaki,K. Ishii,M. Ichimura,M. Yoshikawa,N. Kaidou,S. Fujimoto,T. Cho,T. Yamaguchi,Y. Miyata 한국물리학회 2006 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.49 No.III

The radial particle flux induced by drift-type fluctuations is observed by use of a gold neutral beam probe in the tandem mirror GAMMA 10. When the drift waves are excited in the plasma, the measured phase difference between the density and potential fluctuations is not zero; the radial profile of the phase difference is not constant. This showed that the radial particle flux had some profile and then the density profile would be varied due to the radial particle transport induced by the fluctuations through the radial particle flux. Experimental results showed the density reduction due to the transport induced by the drift-type fluctuations. The phase difference is an important parameter to decide the radial particle flux. The profiles of the phase difference are measured to understand the decision mechanism of the phase difference. The radial profile of the phase difference is varied by the ion heating power, the density and the potential profiles. As a result, the phase difference had a correlation with the difference between the local drift frequency (the electron diamagnetic drift frequency and the E×B drift frequency) and the observed frequency.

X-ray and Neutron Structure Analysis of MeHPLN in the Low Temperature Phase

R. Kiyanagi,A. Kojima,H. Kimura,M. Watanabe,S. Kumazawa,T. Sugawara,T. Hayashide,T. Mochida,Y. Noda 한국물리학회 2003 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.42 No.IV

Structure analyses of 5-Methyl-9-hydroxyphenalenon(C14H10O2, MeHPLN) in the low temperature phase were performed by X-ray and neutron scattering experiments. It is found that the space group is P21/c with a super cell (a 2b c) and there are two types of molecules in the unit cell. In one of the independent molecules, hydrogen atoms in hydrogen-bond region occupy two sites as same as in the room temperature phase. On the other hand, in another independent molecules, hydrogen atoms in hydrogen-bond region clearly show ordering feature. In these ordered hydrogen atoms, there are obvious discrepancy beween electron and nuclear distribution, and hence static electrical dipolemoments exist in hydorgen-bond region with an antiferroelectric ordering.