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Hamaguchi R, Yoshizawa-Fujita M, Miyasaka T, Kunugita H, Ema K, Takeoka Y, Rikukawa M. Formamidine and cesium-based quasi-two-dimensional perovskites as photovoltaic absorbers. Chem Commun (Camb) 2017; 53:4366-4369. [DOI: 10.1039/c7cc00921f] [Citation(s) in RCA: 58] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Formamidine and Cs-based quasi two-dimensional perovskites were newly synthesized for photovoltaic solar cells.
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Affiliation(s)
- R. Hamaguchi
- Faculty of Science and Engineering
- Sophia University
- Tokyo
- Japan
| | | | - T. Miyasaka
- Graduate School of Engineering
- Toin University of Yokohama
- Yokohama 225-8503
- Japan
| | - H. Kunugita
- Faculty of Science and Engineering
- Sophia University
- Tokyo
- Japan
| | - K. Ema
- Faculty of Science and Engineering
- Sophia University
- Tokyo
- Japan
| | - Y. Takeoka
- Faculty of Science and Engineering
- Sophia University
- Tokyo
- Japan
| | - M. Rikukawa
- Faculty of Science and Engineering
- Sophia University
- Tokyo
- Japan
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Sasaki Y, Le KV, Aya S, Isobe M, Yao H, Huang CC, Takezoe H, Ema K. High-resolution calorimetric study of phase transitions in chiral smectic-C liquid crystalline phases. Phys Rev E Stat Nonlin Soft Matter Phys 2012; 86:061704. [PMID: 23367966 DOI: 10.1103/physreve.86.061704] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/02/2012] [Indexed: 06/01/2023]
Abstract
We carried out an improved characterization of phase transitions among chiral smectic-C subphases observed for various antiferroelectric liquid crystals by precise heat capacity measurements. It was found that the phase transitions are intrinsically first order exhibiting a remarkable heat anomaly which involves little pretransitional thermal fluctuation and a finite thermal hysteresis. On the other hand, we also noticed that the critical point of the smectic-C(α)(*)-smectic-C* transition is induced by the destabilization of the smectic-C(α)(*) phase which couples with the fluctuation associated with the smectic-A-smectic-C(α)(*) phase transition.
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Affiliation(s)
- Y Sasaki
- Department of Physics, Tokyo Institute of Technology, O-okayama, Meguro, Tokyo 152-8551, Japan
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Sasaki Y, Nagayama H, Araoka F, Yao H, Takezoe H, Ema K. Distinctive thermal behavior and nanoscale phase separation in the heterogeneous liquid-crystal B4 matrix of bent-core molecules. Phys Rev Lett 2011; 107:237802. [PMID: 22182125 DOI: 10.1103/physrevlett.107.237802] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/24/2011] [Revised: 10/13/2011] [Indexed: 05/31/2023]
Abstract
By means of high-resolution calorimetry, we studied thermodynamic properties of the liquid-crystal B(4) phase where bent-core molecules form a helical nanofilament structure. Distinctive thermal behavior characterizing the growth process of the B(4) phase was obtained in undergoing the phase transition with many sharp peaks, indicating a highly heterogeneous structure. It has been demonstrated that such unusual behavior is commonly seen for two types of rodlike molecules as well as for various mixture compositions. We speculate that mixture systems involve a nanoscale phase-separated structure due to the remarkable aggregation effect in the bent-core molecules and that the helical nanofilament structure independently grows in the isotropic state of rodlike molecules. We also propose that the asymmetry in viscoelastic property plays a role in yielding unusual behavior.
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Affiliation(s)
- Y Sasaki
- Department of Physics, Tokyo Institute of Technology, O-okayama, Meguro, Tokyo 152-8551, Japan
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Sasaki Y, Ema K, Le KV, Takezoe H, Dhara S, Sadashiva BK. Calorimetric study of the effect of bent-shaped dopant molecules on the critical behavior at the nematic-smectic-Ad phase transition. Phys Rev E 2011; 83:061701. [PMID: 21797381 DOI: 10.1103/physreve.83.061701] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2010] [Revised: 03/29/2011] [Indexed: 11/07/2022]
Abstract
We report results of calorimetric studies for the binary mixture of rodlike host n-alkyloxy-cyanobiphenyl (nOCB, n=8,9) and bent-shaped guest 1,3-phenylene-bis[4-(3-methylbenzoyloxy)]-4'-n-dodecylbiphenyl-4'-carboxylate (BC12). The effect of bent-shaped dopant molecules on the critical behavior associated with the nematic-smectic-A(d) phase transition has been studied in detail. The transition temperature for the nematic-smectic-A(d) phase sharply decreases as the increase of the mole fraction of the dopant concentration (denoted X for the BC12/9OCB mixture and Y for the BC12/8OCB mixture). The dependence of the critical exponent α on X and Y is well explained in terms of the McMillan ratio. A nearly tricritical exponent has been obtained for the X=0.01 mixture. X=0.02-0.03 mixtures, pure 8OCB, and Y=0.01-0.03 mixtures exhibit nonuniversal behaviors with effective exponents lying between the 3D-XY and tricritical exponents. The heat capacity anomaly for Y=0.05 has been well described with the 3D-XY exponent. The critical amplitude ratio A(-)/A(+) is close to 1 and insensitive to the dopant concentration. No Fisher renormalization of the critical exponent has been observed even for nearly tricritical compositions, which indicates the smallness of the concentration plays a decisive role rather than the steepness of the N-SmA(d) phase boundary.
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Affiliation(s)
- Y Sasaki
- Department of Physics, Tokyo Institute of Technology, O-okayama, Meguro, Japan
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5
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Sasaki Y, Ema K, Le KV, Takezoe H, Dhara S, Sadashiva BK. Critical behavior at transitions from uniaxial to biaxial phases in a smectic liquid-crystal mixture. Phys Rev E Stat Nonlin Soft Matter Phys 2010; 82:011709. [PMID: 20866637 DOI: 10.1103/physreve.82.011709] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/17/2010] [Indexed: 05/29/2023]
Abstract
We report results of calorimetric and optical investigations of binary mixtures of rodlike and bent-shaped molecules. We find that the observed critical heat anomaly associated with the smectic-A2 to biaxial smectic-A2b transition is well described with a Fisher-renormalized form of the usual scaling expression. The effect of renormalization is large in this system in part because of the moderately steep slope of the phase boundary (dT(c)/ dX∼100 K, where X is the mole fraction of the bent-core molecules) and in part because of the proximity to the tricritical point. The magnitude of heat anomaly at the smectic-A2-smectic-A2b transition showed a drastic decrease as X becomes smaller. Moreover, the nematic-smectic-A2 transitions investigated turned out to be always first order and the transition enthalpy showed only weak dependence on the concentration X. The results imply that the energy fluctuations around the smectic-A2-smectic-A2b transition are very sensitive to the underlying ordering of the smectic-A2 background.
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Affiliation(s)
- Y Sasaki
- Department of Physics, Tokyo Institute of Technology, 2-12-1 O-okayama, Meguro, Tokyo 152-8551, Japan
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6
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Ema K, Inomata M, Kato Y, Kunugita H, Era M. Nearly perfect triplet-triplet energy transfer from Wannier excitons to naphthalene in organic-inorganic hybrid quantum-well materials. Phys Rev Lett 2008; 100:257401. [PMID: 18643701 DOI: 10.1103/physrevlett.100.257401] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/09/2008] [Indexed: 05/24/2023]
Abstract
We report the observation of extremely efficient energy transfer (greater than 99%) in an organic-inorganic hybrid quantum-well structure consisting of perovskite-type lead bromide well layers and naphthalene-linked ammonium barrier layers. Time-resolved photoluminescence measurements confirm that the transfer is triplet-triplet Dexter-type energy transfer from Wannier excitons in the inorganic well to the triplet state of naphthalene molecules in the organic barrier. Using measurements in the 10-300 K temperature range, we also investigated the temperature dependence of the energy transfer.
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Affiliation(s)
- K Ema
- Department of Physics, Sophia University, 7-1 Kioi-cho, Chiyoda-ku, Tokyo 102-8554, Japan
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McCoy BK, Liu ZQ, Wang ST, Pindak R, Takekoshi K, Ema K, Seed A, Huang CC. Smectic-C*alpha phase with two coexistent helical pitch values and a first-order smectic-C*alpha to smectic-C* transition. Phys Rev E Stat Nonlin Soft Matter Phys 2007; 75:051706. [PMID: 17677083 DOI: 10.1103/physreve.75.051706] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/01/2007] [Indexed: 05/16/2023]
Abstract
Previous results from Kundu using dielectric relaxation have suggested a reentrant antiferroelectric-ferroelectric-antiferroelectric transition in the compound LN36. Our comprehensive studies of this compound using differential optical reflectivity, nonadiabatic scanning calorimetry, null transmission ellipsometry, and resonant x-ray diffraction show that in fact LN36 exhibits the usual phase sequence for chiral smectic liquid crystals: SmA*-SmC*alpha-SmC*-SmC*FI1-SmC*A . Moreover, the SmC*alpha-SmC* transition is a first-order transition, characterized by a discontinuous change in the helical pitch. At temperatures just above the SmC*alpha-SmC* transition, two different values for the helical pitch are simultaneously observed for the first time.
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Affiliation(s)
- B K McCoy
- School of Physics and Astronomy, University of Minnesota, Minneapolis, MN 55455, USA
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Takekoshi K, Sasaki Y, Ema K, Yao H, Takanishi Y, Takezoe H. Quasi-two-dimensional Ising critical behavior of de Vries liquid crystals observed in the heat capacity and dielectric response. Phys Rev E Stat Nonlin Soft Matter Phys 2007; 75:031704. [PMID: 17500708 DOI: 10.1103/physreve.75.031704] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/02/2006] [Indexed: 05/15/2023]
Abstract
Heat capacity and dielectric measurements have been made on a liquid crystal compound exhibiting de Vries type of smectic-A{*} (Sm-A{*}) phase. Heat capacity shows a significant anomaly which is almost symmetric for above and below the Sm-A{*}-Sm-C{*} transition temperature. The transition was found to be very weakly first order. The critical exponent gamma determined from the dielectric data lies 1.8+/-0.2. The present heat capacity data as well as former data for another compound of de Vries type have been analyzed in detail. It was found that the heat capacity data for both compounds are fitted well with a logarithmic divergence except in the immediate vicinity of the transition. These results agree with an expectation that de Vries Sm-A{*}-Sm-C-{*} transition can exhibit quasi-two-dimensional Ising critical behavior.
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Affiliation(s)
- K Takekoshi
- Department of Physics, Graduate School of Science and Engineering, Tokyo Institute of Technology, 2-12-1 Oh-okayama, Meguro, Tokyo, 152-8550, Japan
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Takekoshi K, Ema K, Yao H, Takanishi Y, Watanabe J, Takezoe H. Appearance of a liquid crystalline nematic-isotropic critical point in a mixture system of rod- and bent-shaped molecules. Phys Rev Lett 2006; 97:197801. [PMID: 17155658 DOI: 10.1103/physrevlett.97.197801] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/27/2006] [Indexed: 05/12/2023]
Abstract
Heat capacity measurements have been made on a liquid-crystal mixture system formed from bent-shaped molecule 1,3-phenylene bis[4-(4-8-alkoxyphenyliminomethyl)benzoates] (P-8-O-PIMB) and rod-shaped molecule n-pentyl-cyanobiphenyl (5CB). The obtained results can be understood assuming that the addition of P-8-O-PIMB molecules to the 5CB system affects as a field conjugate to the nematic order parameter. The B(X)-B(4) transition can be viewed as the nematic-isotropic transition of 5CB, which is embedded in a framework of the B(4) structure of P-8-O-PIMB molecules. The present mixture system offers a rare example of the nematic-isotropic critical point, whose critical behavior has not been studied yet in detail.
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Affiliation(s)
- K Takekoshi
- Department of Physics, Graduate School of Science and Engineering, Tokyo Institute of Technology, 2-12-1 Oh-okayama, Meguro, Tokyo 152-8550, Japan
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Liu ZQ, Wang ST, McCoy BK, Cady A, Pindak R, Caliebe W, Takekoshi K, Ema K, Nguyen HT, Huang CC. Smectic-Calpha*-smectic-C* phase transition and critical point in binary mixtures. Phys Rev E Stat Nonlin Soft Matter Phys 2006; 74:030702. [PMID: 17025581 DOI: 10.1103/physreve.74.030702] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/16/2006] [Indexed: 05/12/2023]
Abstract
We have investigated the smectic-Calpha*-smectic-C* (SmCalpha*-SmC*) transition in a series of binary mixtures with resonant x-ray diffraction, differential optical reflectivity, and heat capacity measurements. Results show that the phases are separated by a first-order transition that ends at a critical point. We report the observation of such a critical point. We have proposed the appropriate order parameter and obtained values of two critical exponents associated with this transition. The values of the critical exponents suggest that long-range interactions are present in the SmCalpha*-SmC* critical region.
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Affiliation(s)
- Z Q Liu
- School of Physics and Astronomy, University of Minnesota, Minneapolis, Minnesota 55455, USA
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Ema K, Takekoshi K, Yao H, Wang ST, Huang CC. Calorimetric investigations of liquid-crystal compounds exhibiting almost no layer-shrinkage behavior through the smectic-A-smectic- C* transition. Phys Rev E Stat Nonlin Soft Matter Phys 2005; 71:031706. [PMID: 15903446 DOI: 10.1103/physreve.71.031706] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/01/2004] [Indexed: 05/02/2023]
Abstract
Heat-capacity measurements have been made on liquid-crystal compounds exhibiting almost no layer-shrinkage (NLS) behavior through the Sm-A-Sm- C(*) phase transition. The transition was found to be second order for two of the substances studied. It was found that the heat-capacity anomaly accompanying a second-order Sm-A-Sm- C(*) transition with NLS behavior is quite similar to that observed for typical antiferroelectric liquid crystals of the 4-(1-methylheptyloxycarbonyl)phenyl 4'-octyloxybiphenyl-4-carboxylate (MHPOBC) group, showing three-dimensional (3D) XY behavior in the vicinity of the transition. On the other hand, for one compound which shows a weakly first-order transition, the anomaly is almost symmetric above and below T(c) , with a significant fluctuation effect in the Sm-A phase. For this compound, the critical behavior of the heat-capacity anomaly is almost tricritical in the immediate vicinity of T(c) , while away from T(c) the behavior can be explained with the 3D XY model. This suggests that the underlying transition with the 3D XY critical behavior is driven to almost being tricritical but remaining weakly first order. No indication of low-dimensional character in the critical behavior was found in both cases.
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Affiliation(s)
- K Ema
- Department of Physics, Graduate School of Science and Engineering, Tokyo Institute of Technology, Meguro, Japan.
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Huang CC, Wang ST, Han XF, Cady A, Pindak R, Caliebe W, Ema K, Takekoshi K, Yao H. Experimental investigations of one liquid-crystal compound exhibiting the no-layer-shrinkage effect near the Sm-A-Sm- C(*) transition. Phys Rev E Stat Nonlin Soft Matter Phys 2004; 69:041702. [PMID: 15169028 DOI: 10.1103/physreve.69.041702] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/12/2003] [Indexed: 05/24/2023]
Abstract
Three experimental probes have been employed to investigate the nature of the smectic- A -smectic- C ( Sm-A-Sm- C(*) ) phase transition of one liquid-crystal compound showing almost no layer-shrinkage effect through the transition. Results from both x-ray diffraction and optical studies indicate that the compound exhibits a crossover behavior of different molecular packing arrangements within the bulk Sm-A phase window. The calorimetry results show a significant critical anomaly near the Sm-A-Sm- C(*) transition, although it was found to be weakly first order.
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Affiliation(s)
- C C Huang
- School of Physics and Astronomy, University of Minnesota, Minneapolis, Minnesota 55455, USA
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Hirotsu S, Miyamota M, Ema K. Three-state Potts transition in sodium azide: experimental study of an order of the transition by means of a heat capacity measurement. ACTA ACUST UNITED AC 2000. [DOI: 10.1088/0022-3719/16/19/001] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Ema K, Kanai M, Yao H, Takanishi Y, Takezoe H. Effect of optical purity on the critical heat capacity at the smectic-A-(chiral)-smectic-C transition in an antiferroelectric liquid crystal. Phys Rev E Stat Phys Plasmas Fluids Relat Interdiscip Topics 2000; 61:1585-92. [PMID: 11046441 DOI: 10.1103/physreve.61.1585] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/14/1999] [Revised: 10/19/1999] [Indexed: 04/15/2023]
Abstract
High resolution ac calorimetric measurements have been carried out near the smectic-A-chiral-smectic-C phase transition in the antiferroelectric liquid crystal 4-(1-methylheptyloxycarbonyl)phenyl 4(')-octyloxybiphenyl-4-carboxylate (MHPOBC). Data on samples with different optical purities have been analyzed in detail using a renormalization-group expression with corrections-to-scaling terms. The chiral-smectic-C(alpha)-chiral-smectic-C phase transition is first order, while the smectic-A-chiral-smectic-C(alpha) phase transition is second order. A direct smectic-A-chiral-smectic-C phase transition, which occurs in near-racemic mixtures, was found to be quasitricritical and weakly first order. This implies that the smectic-A-smectic-C transition in the racemate locates at a special point where four critical lines intersect.
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Affiliation(s)
- K Ema
- Department of Physics, Faculty of Science, Tokyo Institute of Technology, 2-12-1 Oh-okayama, Meguro, Tokyo 152-8551, Japan
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Ema K, Yao H, Fukuda A, Takanishi Y, Takezoe H. Non-Landau critical behavior of heat capacity at the smectic-A-smectic-C alpha * transition of the antiferroelectric liquid crystal methylheptyloxycarbonylphenyl octyloxycarbonylbiphenyl carboxylate. Phys Rev E Stat Phys Plasmas Fluids Relat Interdiscip Topics 1996; 54:4450-4453. [PMID: 9965602 DOI: 10.1103/physreve.54.4450] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Ema K, Ogawa M, Takagi A, Yao H. Crossover from XY critical to tricritical behavior of heat capacity at the smectic-A-chiral-smectic-C liquid-crystal transition. Phys Rev E Stat Phys Plasmas Fluids Relat Interdiscip Topics 1996; 54:R25-R28. [PMID: 9965166 DOI: 10.1103/physreve.54.r25] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Ema K, Takagi A, Yao H. Gaussian tricritical behavior of heat capacity at the smectic-A-smectic-C liquid crystal transition. Phys Rev E Stat Phys Plasmas Fluids Relat Interdiscip Topics 1996; 53:R3036-R3039. [PMID: 9964760 DOI: 10.1103/physreve.53.r3036] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
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Nagano H, Nakanishi T, Yao H, Ema K. Effect of vesicle size on the heat capacity anomaly at the gel to liquid-crystalline phase transition in unilamellar vesicles of dimyristoylphosphatidylcholine. Phys Rev E Stat Phys Plasmas Fluids Relat Interdiscip Topics 1995; 52:4244-4250. [PMID: 9963895 DOI: 10.1103/physreve.52.4244] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
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Ema K, Kuwata-Gonokami M. Solitonlike propagation of exciton-polariton pulses supported by biexciton two-photon dispersion. Phys Rev Lett 1995; 75:224-227. [PMID: 10059640 DOI: 10.1103/physrevlett.75.224] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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Ema K, Watanabe J, Takagi A, Yao H. Critical behavior of heat capacity at the smectic-C alpha *-smectic-A transition of the antiferroelectric liquid crystal methylheptyloxycarbonylphenyl octyloxybiphenyl carboxylate (MHPOBC). Phys Rev E Stat Phys Plasmas Fluids Relat Interdiscip Topics 1995; 52:1216-1219. [PMID: 9963531 DOI: 10.1103/physreve.52.1216] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
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Nagano H, Yao H, Ema K. Dynamic heat capacity at the gel to liquid-crystalline phase transition in large unilamellar vesicles of dimyristoylphosphatidylcholine in the ultralow frequency region. Phys Rev E Stat Phys Plasmas Fluids Relat Interdiscip Topics 1995; 51:3363-3367. [PMID: 9963016 DOI: 10.1103/physreve.51.3363] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
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22
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Yao H, Nagano H, Kawase Y, Ema K. Slow relaxation process in the main transition of phosphatidylcholines studied with heat capacity spectroscopy. I. Multilamellar vesicles. Biochim Biophys Acta 1994; 1212:73-9. [PMID: 8155729 DOI: 10.1016/0005-2760(94)90191-0] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Extremely slow relaxation processes have been examined near the main transition of multilamellar vesicle samples of dimyristoylphosphatidylcholine (DMPC) and dipalmitoylphosphatidylcholine (DPPC) with a heat capacity spectroscopic technique. The dynamic heat capacity showed a significant frequency dependence in the studied frequency region of 0.5 mHz to 50 mHz. The relaxation observed here has been analyzed with the Cole-Cole equation. The mean relaxation times were 120 s in DMPC, and 260 s in DPPC. The relaxation showed a polydispersive character. The parameter beta was around 0.5 in both DMPC and DPPC.
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Affiliation(s)
- H Yao
- Department of Physics, Faculty of Science, Tokyo Institute of Technology, Japan
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Ema K, Yao H, Kawamura I, Chan T, Garland CW. High-resolution calorimetric study of the antiferroelectric liquid crystals methylheptyloxycarbonylphenyl octyloxybiphenyl carboxylate and its octylcarbonylbiphenyl analog. Phys Rev E Stat Phys Plasmas Fluids Relat Interdiscip Topics 1993; 47:1203-1211. [PMID: 9960123 DOI: 10.1103/physreve.47.1203] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Ema K, Nounesis G, Garland CW, Shashidhar R. Calorimetric study of smectic polymorphism in octyloxyphenyl-nitrobenzoyloxy benzoate + decyloxyphenyl-nitrobenzoyloxy benzoate mixtures. Phys Rev A Gen Phys 1989; 39:2599-2608. [PMID: 9901531 DOI: 10.1103/physreva.39.2599] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
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Ema K, Garland CW, Sigaud G, Tinh NH. Heat capacity associated with nematic-smetic-A1-smectic-A-bar-smectic-A(crenelated)-smectic-A2 phase sequence. Phys Rev A Gen Phys 1989; 39:1369-1375. [PMID: 9901374 DOI: 10.1103/physreva.39.1369] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
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Shimada K, Fujisaki H, Oketani K, Murakami M, Shoji T, Wakabayashi T, Ueda K, Ema K, Hashimoto K, Tanaka S. Synthesis and gastric antisecretory activity of N-cyano-N'-(phenyl-pyridinylmethyl)guanidine derivatives. Chem Pharm Bull (Tokyo) 1984; 32:4893-906. [PMID: 6534538 DOI: 10.1248/cpb.32.4893] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
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Ema K, Kato T, Shinagawa M. [Amination of oxy acids in aqueous solution by gamma-irradiation (author's transl)]. Radioisotopes 1978; 27:445-9. [PMID: 734162 DOI: 10.3769/radioisotopes.27.8_445] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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Ema K, Hikichi T, Shinagawa M. [Effect of additives on the amination of 2-oxoglutaric acid by gamma-radiation]. Radioisotopes 1977; 26:447-50. [PMID: 578970 DOI: 10.3769/radioisotopes.26.7_447] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The effect of added substances was studied on the yield of glutamic acid produced by gamma-ray irradiation of 2-oxoglutaric acid and ammonia in aqueous solution. The contents of amino acids in the irradiated solutions were determined with amino acids analyzer. Sodium nitrate, allyl alcohol or sodium formate was used as an added substance. The yield of glutamic acid significantly decreased by the addition of nitrate, and it was little affected by the addition of allyl alcohol. In the presence of formate the yield increased from G = 0.4 (2-oxoglutaric acid 0.05M and ammonium hydroxide 2M) to G = 1.1. As a result, it was found that hydrated electron contributes on the formation of glutamic acid, but hydroxyl radical does not. The yield showed a maximum at ca. 0.1 M ammonium hydroxide concentration. These facts indicate that NH2 radical does not contribute to the formation of glutamic acid. As a reaction mechanism, it can be explained that 2-oxoglutaric acid which had been reduced by hydrated electron reacts with ammonia.
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