Relaxation behaviors of enantiomorphic S-ibuprofen as revealed by dielectric and photon correlation spectroscopies

Shin, D.M.,Hwang, Y.H.,Ko, J.H.,Kojima, S. Elsevier 2015 CURRENT APPLIED PHYSICS Vol.15 No.9

Relaxation behaviors of enantiomorphic S-ibuprofen were investigated in its amorphous state by using dielectric and photon correlation spectroscopies. The dielectric relaxation processes of the S-ibuprofen were nearly identical to those of the racemic RS-ibuprofen. The relaxation parameters and the dielectric strengths of the α-process and the D-process for the S-ibuprofen were very similar to those for the RS-ibuprofen. These results indicate that the stereochemistry of ibuprofen molecules do not have any substantial effect on molecular motions in the amorphous state of ibuprofen. The relaxation times of the main relaxation process probed by using the photon correlation spectroscopy were consistent with those of the dielectric α-process. The fragility of the S-ibuprofen was 76, which was nearly the same to that determined based on the thermal relaxation times and smaller than that of the racemic compound.

Comparison of thermal and elastic properties of glassy racemic and enantiomorphic ibuprofen studied by Brillouin light scattering and modulated differential scanning calorimetry

Kim, T.H.,Shibata, T.,Kojima, S.,Shin, D.M.,Hwang, Y.H.,Ko, J.H. Elsevier 2014 CURRENT APPLIED PHYSICS Vol.14 No.7

The vitrification process of racemic RS- and enantiomorphic S-ibuprofen was studied by using Brillouin light scattering and modulated differential scanning calorimetry (DSC). The sound velocity and the attenuation coefficient of both compounds were determined for the first time in the glassy, supercooled liquid and liquid states. The sound velocity and the hypersonic damping were similar between the two ibuprofen pharmaceuticals over the whole investigated temperature range including glassy, supercooled liquid and liquid states. The thermal expansion coefficient of the RS-ibuprofen was smaller than that of the S-ibuprofen, which suggests that the intermolecular force of the former is slightly stronger than the latter. The thermal relaxation times derived from the modulated DSC were consistent with the dielectric relaxation times in both RS- and S-ibuprofens. The fragility index of S-ibuprofen just above the glass transition was determined to be 73, which was smaller compared to the value of RS-ibuprofen, 89. This difference in the fragility indicates that the decrease in the fragility of S-ibuprofen compared to the racemic one may improve its stability of the amorphous state below the glass transition temperature against crystallization.

Extension of Completely Positive Cone Relaxation to Moment Cone Relaxation for Polynomial Optimization

Arima, N.,Kim, S.,Kojima, M. Springer Science + Business Media 2016 Journal of optimization theory and applications Vol.168 No.3

<P>We propose the moment cone relaxation for a class of polynomial optimization problems to extend the results on the completely positive cone programming relaxation for the quadratic optimization model by Arima, Kim and Kojima. The moment cone relaxation is constructed to take advantage of sparsity of the polynomial optimization problems, so that efficient numerical methods can be developed in the future. We establish the equivalence between the optimal value of the polynomial optimization problem and that of the moment cone relaxation under conditions similar to the ones assumed in the quadratic optimization model.</P>

Broadband micro-Brillouin scattering spectroscopy of Pb(B_1/3B'_2/3)O₃-based relaxor ferroelectrics

Kojima, S.,Ko, J.H. Elsevier 2011 CURRENT APPLIED PHYSICS Vol.11 No.3

The colossal piezoelectric effect of relaxor-based ferroelectrics has attracted much attention due to the technological importance of the conversion between electric and mechanical energies. The mechanism of the significant field effect on piezoelectric properties in this disordered system has become one of the current topics in pure and applied physics. The important key factor in the understanding of relaxors is polar nanoregions (PNRs) which appear at temperatures far above the dielectric maximum or Curie temperature. PNRs play a dominant role in the formation of unique characteristics of relaxors and are regarded to be caused by spatial and dynamic heterogeneity. However, a detailed microscopic picture of their evolution depending on temperature or electric field is still the subject of controversy. The elastic and dynamical properties of the Pb(B<SUB>1/3</SUB>B'<SUB>2/3</SUB>)O<SUB>3</SUB>-type relaxor-based ferroelectrics and their solid solutions with pure ferroelectrics have recently been studied extensively by the broadband micro-Brillouin scattering spectroscopy (BMBS) to clarify the role of PNRs. This paper reviews the recent progress in the understanding of fast dynamics of PNRs of typical relaxor-based ferroelectrics of (1-x)Pb(Mg<SUB>1/3</SUB>Nb<SUB>2/3</SUB>)O<SUB>3</SUB>-xPbTiO<SUB>3</SUB> and (1-x)Pb(Zn<SUB>1/3</SUB>Nb<SUB>2/3</SUB>)O<SUB>3</SUB>-xPbTiO<SUB>3</SUB> in the gigahertz frequency range achieved by using BMBS.

Successive Phase Transitions of Ferroelectric Bi3.6La0.4Ti3O12 Crystals Studied by Using Brillouin Scattering

M. S. Islam,S. Tsukada,M.-S. Jang,S. Kojima 한국물리학회 2009 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.55 No.2

The dynamical properties of Bi3.6La0.4Ti3O12 single crystals have been investigated by using Brillouin scattering. Two elastic anomalies are clearly observed, one around 290℃ (TO−M) and the other around 685℃ (TT−O), corresponding to the orthorhombic-monoclinic and the tetragonalorthorhombic phase transition temperatures, respectively. A central peak (CP) appears clearly in the vicinity of TO−M. The relaxation time determined from the full width at half maximum (FWHM) of the CP indicates a critical slowing down of the polarization fluctuation along the c-axis in the vicinity of TO−M, which is attributed to the order-disorder nature of an orthorhombicmonoclinic phase transition, while the absence of a CP near TT−O is due to the displacive nature of a tetragonal-orthorhombic phase transition. The dynamical properties of Bi3.6La0.4Ti3O12 single crystals have been investigated by using Brillouin scattering. Two elastic anomalies are clearly observed, one around 290℃ (TO−M) and the other around 685℃ (TT−O), corresponding to the orthorhombic-monoclinic and the tetragonalorthorhombic phase transition temperatures, respectively. A central peak (CP) appears clearly in the vicinity of TO−M. The relaxation time determined from the full width at half maximum (FWHM) of the CP indicates a critical slowing down of the polarization fluctuation along the c-axis in the vicinity of TO−M, which is attributed to the order-disorder nature of an orthorhombicmonoclinic phase transition, while the absence of a CP near TT−O is due to the displacive nature of a tetragonal-orthorhombic phase transition.

Mechanistic insight into catalytic oxidations of organic compounds by ruthenium(IV)-oxo complexes with pyridylamine ligands

Ohzu, S.,Ishizuka, T.,Hirai, Y.,Jiang, H.,Sakaguchi, M.,Ogura, T.,Fukuzumi, S.,Kojima, T. THE ROYAL SOCIETY OF CHEMISTRY 2012 Chemical Science Vol.3 No.12

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>

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.

Brillouin scattering study on crystalline and glassy states of anti-inflammatory racemic S(+)-R(-) ibuprofen

Ko, J.H.,Kim, T.H.,Lee, K.S.,Kojima, S. North Holland ; Elsevier Science Ltd 2011 Chemical physics letters Vol.515 No.4

The acoustic properties of racemic S(+)-R(-) ibuprofen single crystals and amorphous ibuprofen were investigated by Brillouin light scattering. The temperature dependence of the longitudinal acoustic (LA) mode in crystalline ibuprofen could be explained by normal anharmonic lattice models. The LA mode frequency of amorphous ibuprofen exhibited a clear change at ∼228K at which glassy ibuprofen changes into supercooled-liquid state. The acoustic damping of the LA mode in both glassy and crystalline ibuprofen were similar. This indicated the molecular fluctuations remnant in the glassy ibuprofen are comparable to crystalline ibuprofen, which may be attributable to the strong hydrogen-bonded aggregates in both states.

Demonstration of long-pulse acceleration of high power positive ion beam with JT-60 positive ion source in Japan-Korea joint experiment

the NB Heating Technology Group,Kojima, A.,Hanada, M.,Jeong, S.H.,Bae, Y.S.,Chang, D.H.,Kim, T.S.,Lee, K.W.,Park, M.,Jung, B.K.,Mogaki, K.,Komata, M.,Dairaku, M.,Kashiwagi, M.,Tobari, H.,Watanabe, K. North-Holland ; Elsevier Science Ltd 2016 Fusion engineering and design Vol.102 No.-

The long-pulse acceleration of the high-power positive ion beam has been demonstrated with the JT-60 positive ion source in the joint experiment among Japan Atomic Energy Agency (JAEA), Korea Atomic Energy Research Institute (KAERI) and National Fusion Research Institute (NFRI) under the collaboration program for the development of plasma heating and current drive systems. In this joint experiment, the increase of the heat load and the breakdowns induced by the degradation of the beam optics due to the gas accumulation was one of the critical issues for the long-pulse acceleration. As a result of development of the long-pulse operation techniques of the ion source and facilities of the neutral beam test stand in KAERI, 2MW 100s beam has been achieved for the first time. The achieved beam performance satisfies the JT-60SA requirement which is designed to be a 1.94MW ion beam power from an ion source corresponding to total neutral beam power of 20MW with 24 ion sources. Therefore, it was found that the JT-60 positive ion sources were applicable in the JT-60SA neutral beam injectors. Moreover, because this ion source is planned to be a backup ion source for KSTAR, the operational region and characteristic has been clarified to apply to the KSTAR neutral beam injector.