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Quorum sensing (QS) is a microbial signaling system that regulates the expression of many virulence genes. Herein, we studied five compounds-No. 1: (E)-2-methyl-3- (4-nitro-phenyl)-acrylaldehyde; No. 29-2: pimprinine [5-(1H-indol-3-yl)-2-methyloxazole]; No. 48: (2E,4E)-2-methyl-5-phenyl-2,4-pentadienoic acid; No. 74: (3E,5E)-5-methyl-6-(4-nitrophenyl)-hexa-3,5-dien-2-ol; and No. 130: methyphenazine-1-carboxylate-derived from an actinomycete metabolite library. These compounds were confirmed to be QS inhibitors that reduced violacein production in Chromobacterium violaceum CV026. Additionally, compounds No. 1, No. 74, and No. 130 significantly reduced fluorescent pigment production in Pseudomonas aeruginosa ATCC 27853.

Quorum sensing (QS) is a microbial signaling system that regulates the expression of many virulence genes. Herein, we studied five compounds-No. 1: (E)-2-methyl-3- (4-nitro-phenyl)-acrylaldehyde; No. 29-2: pimprinine [5-(1H-indol-3-yl)-2-methyloxazole]; No. 48: (2E,4E)-2-methyl-5-phenyl-2,4-pentadienoic acid; No. 74: (3E,5E)-5-methyl-6-(4-nitrophenyl)-hexa-3,5-dien-2-ol; and No. 130: methyphenazine-1-carboxylate-derived from an actinomycete metabolite library. These compounds were confirmed to be QS inhibitors that reduced violacein production in Chromobacterium violaceum CV026. Additionally, compounds No. 1, No. 74, and No. 130 significantly reduced fluorescent pigment production in Pseudomonas aeruginosa ATCC 27853.

The intermetallic compound H (Mn$_7$Si$_2$V) phase in the Mn-Si-V alloy system can be regarded as an approximant phase of the dodecagonal quasicrystal as one of the two-dimensional quasicrystals. To understand the features of the approximant H phase, in this study, the crystallographic features of both the H phase and the (\sigma $\, \rightarrow$ H) reaction in Mn-Si-V alloy samples were investigated, mainly by transmission electron microscopy. It was found that, in the H phase, there were characteristic structural disorders with respect to an array of a dodecagonal structural unit consisting of 19 dodecagonal atomic columns. Concretely, penetrated structural units consisting of two dodecagonal structural units were presumed to be typical of such disorders. An interesting feature of the (\sigma $\, \rightarrow$ H) reaction was that regions with a rectangular arrangement of penetrated structural units (RAPU) first appeared in the \sigma $\,$ matrix as the initial state, and H regions were then nucleated in contact with RAPU regions. The subsequent conversion of RAPU regions into H regions eventually resulted in the formation of the approximant H state as the final state. Furthermore, atomic positions in both the H structure and the dodecagonal quasicrystal were examined using a simple plane-wave model with twelve plane waves., Comment: 29 pages, 12 figures

The crystallographic features of the (α-Mn → α-Mn + β-Samson) reaction in Al-Mg alloys around the composition of 48 at.% Mg have been investigated mainly by transmission electron microscopy to understand the formation of giant atomic clusters in the β-Samson structure. It was confirmed, for instance, that the state of an Al-48 at.% Mg alloy annealed at 573 K for 24 h could be identified as the (α-Mn + β-Samson) coexistence state, and that metastable states were found locally in α-Mn/β-Samson boundary regions. An analysis of electron diffraction patterns obtained from the coexistence state indicated that the orientation relationship of ( 3 ¯ 30)α//( 8 ¯ 80)β-S and [110]α//[110]β-S was established between α-Mn and β-Samson regions, together with a lattice contraction of about 10% along the [001]α direction and an expansion of about 0.4% along the [ 1 ¯ 10]α direction in the (α-Mn → β-Samson) structural change. High-resolution electron micrographs of the coexistence state also suggested that some atoms at the Mg (I) and Mg (II) sites in the distorted α-Mn structure could be converted to those at the Mg (23) site of the β-Samson structure as the center site of the Samson cluster. Furthermore, both the features of giant clusters in the β-Samson structure and their formation from the α-Mn structure were discussed on the basis of the experimental data obtained in this study.

Crystallographic and morphologic features of quadruple and double superstructures in $\mathrm{B}{\mathrm{i}}_{1\ensuremath{-}x}\mathrm{S}{\mathrm{m}}_{x}\mathrm{Fe}{\mathrm{O}}_{3}$ with $0\ensuremath{\le}x\ensuremath{\le}0.40$ were investigated by x-ray powder diffraction and transmission electron microscopy. The presence of a quadruple superstructure accompanied by antiferroic ionic displacements was found near the morphotropic phase boundary between the $R3c$ phase ($0lxl0.10$) and the Pnma phase ($0.25\ensuremath{\le}x\ensuremath{\le}0.40$). The quadruple superlattice phase coexists with a ferroelectric $R3c$ phase at $x=0.15$. These superstructures were found to originate from the freezing of multiple phonon modes related to transverse wave ionic displacements. These findings provide further insight towards understanding the complexity of rare-earth-doped $\mathrm{BiFe}{\mathrm{O}}_{3}$.

The simple-perovskite system Bi1-xLaxFeO3 (BLFO) is one of mixed-oxide systems having the multiferroic BiFeO3 as an end material, which shows the ferroelectric and antiferromagnetic orders in its ground state. Because of the paraelectric nature of LaFeO3 as another end material, the ferroelectric-to-paraelectric state change can be expected to occur in the mixed-oxide system BLFO. The interesting feature of BLFO is that there are both the PbZrO3-type and incommensurately modulated (IM) states in the intermediate La-content range between the ferroelectric-R3c and paraelectric-Pnma states. Although the detailed features of these two states have not been understood sufficiently, in this study, we focus on the IM state around x = 0.20, and have investigated the crystallographic features of prepared BLFO samples with 0.15 ≤ x ≤ 0.35, mainly by transmission electron microscopy. It was found that six kinds of superlattice reflections were, for instance, present in the reciprocal lattice of the state at 300 K for x = 0.20, in addition to fundamental reflections due to the cubic simple-perovskite structure. To understand the appearance of these superlattice reflections, we regarded the state as a modulated-structure state in this study. Concretely, the modulated structure was assumed to be characterized by the appearance of both the incommensurate wave with qI = c and the commensurate wave with qII = c in the normal-Imma structure. In addition, the appearance of the two modulation waves could also produce the superlattice reflections at the c-, c-, and c-type positions in the reciprocal lattice. From the comparison with the experimental data obtained in this study, our modulated-structure model seems to be appropriate for the IM state in the vicinity of the PbZrO3-type/IM state boundary.

In the highly-correlated electron system Sr1-xNdxMnO3 (SNMO) having the simple perovskite structure, there are interesting electronic states, which are related to degrees of charge, orbital, and spin freedoms for eg electrons in Mn ions. Among these states, in the case of SNMO, the C-, A-and CE-type antiferromagnetic states were reported for 0.20 ≤ x ≤ 0.38, for 0.38 ≤ x ≤ 0.48, and for 0.48 ≤ x ≤ 0.52, respectively. The points to note here are that these antiferromagnetic states are directly associated with corresponding orbital orderings, and that the CE-type state also accompanies charge ordering. Because of these features, we were interested in the (A → CE) state change in SNMO. The crystallographic features of prepared SNMO samples with 0.46 ≤ x ≤ 0.50 have thus been investigated mainly by means of a transmission electron microscope equipped with a low-temperature holder. As a result, the state around 100 K for x = 0.48 was first understood to be identified as the Imma state, which includes a large number of orbital-modulated (OM) regions with an average size of about 10 nm. The feature of such regions is that the orbital modulation has an incommensurate periodicity and a charge modulation is absent in them. On the other hand, the CE-type state having the commensurate orbital and charge modulations was also confirmed to be present for x = 0.50. In addition to these two states, the state around 100 K for x = 0.46 was found to be characterized by the coexistence state consisting of the C-type orbital-ordered state and the Imma states including OM regions. In other words, the presence of the A-type orbital-ordered state could not be confirmed in the temperature range between 300 K and about 100 K for 0.46 ≤ x ≤ 0.50 in this study.

In Bi1-xSmxFeO3 (BSFO) having the multiferroic BiFeO3 as an end material, when the Sm content increases from x = 0, it has been reported that the ferroelectric-R3c state is changed into the paraelectric-Pnma state around x = 0.14. The R3c/Pnma state boundary around x = 0.14 can be regarded as a temperature-independent morphotropic-phase boundary (MPB). The notable feature in BSFO is that, in addition to these two states, the antiferroelectric PbZrO3-type state was also found in the vicinity of the MPB. Although the PbZrO3-type state appears as a modulated structure, its detailed features have not been understood yet. We have thus examined the crystallographic features of prepared BSFO samples around x = 0.14, mainly by transmission electron microscopy. The PbZrO3-type state was confirmed to be present in samples with x = 0.15 on the basis of x-ray powder diffraction profiles measured from prepared samples at 300 K. On the other hand, the observation made by transmission electron microscopy indicated that the state for x = 0.15 is characterized by a coexistence state consisting of the ferroelectric-R3c and antiferroelectric PbZrO3-type states. In particular, the crystal structure of the PbZrO3-type state could be identified as a modulated structure with two transverse modulation waves, whose wave vectors are given by q1 = [1/2 0 0]o and q2 = [0 1/2 0]o in the orthorhombic-Pnma notation. In addition, eigenvectors of these two transverse waves were also determined to be parallel to the same [001]o direction.

The highly-correlated electron system Sr1-xSmxMnO3 (SSMO) with the simple-perovskite structure has been found to exhibit fascinating electronic states accompanying antiferromagnetic and ferromagnetic orderings. It was, in particular, reported that the electronic state for 0.46 ≤ x ≤ 0.54 was characterized by the coexistence state consisting of the A-type antiferromagnetic and ferromagnetic states. However, the features of the coexistence state in this Sm-content range have not been understood yet. We have thus investigated the crystallographic features of prepared SSMO samples with 0.46 ≤ x ≤ 0.55, mainly by transmission electron microscopy. As a result, all prepared SSMO samples were first confirmed to have the orthorhombic-Pnma structure at 300 K. When the temperature was lowered from 300 K, in the case of x=0.47, the disordered-Pnma state was found to be transformed into an orbital-modulated (OM) state accompanying an incommensurate modulation. The notable feature of the OM state is that the state becomes unstable with increasing Sm contents at 100 K. In other words, the OM state was never changed into the CE-type state with the orbital and charge modulations. In addition, no orbital-ordered state for the A-type antiferromagnetic ordering was also found for 0.46 ≤ x ≤ 0.55.

The presence of the C- and A-type orbital-ordered states has been reported in the highly-correlated electronic system Sr1-xNdxMnO3 (SNMO). The interesting feature of the oxide system is that an increase in the Nd content leads to the (C-type → A-type) state change across a temperature-independent morphotropic phase boundary (MPB). Although structural fluctuations can be expected near the MPB, the detailed features of the state change have not been understood sufficiently. Thus, the crystallographic features of the state change in SNMO with 0.35 ≤ x ≤ 0.49 have been investigated mainly at 300 K, by x-ray powder diffraction and transmission electron microscopy. It was found that the C-type orbital-ordered state with the tetragonal-I4/mcm symmetry and the disordered orthorhombic-Imma state were present for 0.35 ≤ x ≤ 0.43 and for 0.45 ≤ x ≤ 0.49 at 300 K, respectively. The notable feature of the state change is that disordered regions with the cubic-Pm m symmetry were also found locally for x = 0.43, in addition to the C-type state. Because the rotational-displacement pattern for oxygen octahedra involved in the disordered-Imma state is the same as that in the A-type state, furthermore, the former disordered state may be regarded as a precursor state to the A-type orbital ordering.

In the highly-correlated electronic system Ca 1- x Pr x MnO 3 having the simple perovskite structure, it has been reported that there exists the C-type orbital-ordered (COO) state accompanying an antiferromagnetic ordering for 0.10 ≤ x ≤ 0.25. According to the previous studies concerning orbital-ordered states in simple perovskite manganites, the COO state was understood to be characterized by a spatial array of (3z 2 -r 2 )-type orbitals for 3d electrons in Mn ions. The notable feature of the COO state in Ca 1- x Pr x MnO 3 is that the state with the monoclinic-P2 1 /m symmetry appears as a result of the structural transition from the disordered state with the orthorhombic-Pnma symmetry. Compared with the COO-state formation from the cubic-Pm $\overline 3$ m state, however, the formation from the disordered-Pnma state has not been understood yet. We have thus examined the crystallographic features of the formation of the COO state in Ca 1- x Pr x MnO 3 , mainly by x-ray powder diffraction and transmission electron microscopy. In the case of x = 0.16, for instance, the COO state was found to appear from the disordered-Pnma state around 90 K on cooling. The notable feature of the formation is that, in the Pnma state just before the COO-state formation, characteristic diffuse scattering appeared around each reflection in electron diffraction patterns, together with the splitting of the 200c reflection in x-ray powder diffraction profiles in the pseudo-cubic notation. Based on these experimental data, it is understood that the formation of the COO state in Ca 1- x Pr x MnO 3 accompanies remarkable fluctuations of the C-type orbital ordering in the disordered-Pnma state.

The multiferroic material Bi1-x Sm x FeO3 shows ferroelectric and antiferromagnetic properties in the ground state of the Bi-rich side. When the Sm content increases from x = 0 in BiFeO3, the (ferroelectric-R3c → paraelectric-Pnma) state change occurs around x = 0.14. According to the previous studies on Bi1-x Sm x FeO3, the state boundary between the R3c and Pnma states can be identified as a morphotropic phase boundary (MPB), which is nearly parallel to the temperature axis in the state diagram. The notable feature of Bi1-x Sm x FeO3 is that a remarkable piezoelectric response was also found near the MPB. However, the origin of the remarkable response has not been understood sufficiently. In this study, thus, the crystallographic features in the vicinity of the MPB have been examined by x-ray powder diffraction and transmission electron microscopy. It was confirmed that the R3c and Pnma states were present for 0 ≤ x ≤ 0.15 and for 0.16 ≤ x ≤ 0.30, respectively. In addition to these states, there also existed the PbZrO3-type state around x = 0.15, which was identified as a modulated structure. Based on the analysis of the modulated structure, furthermore, it was suggested that the PbZrO3-type state could be regarded as a 2q state, which is characterized by two transverse modulation waves with k1 = [1/2 0 0]o and k2 = [0 1/2 0]o in the orthorhombic-Pnma notation.

The simple perovskite manganite Sr1-x Sm x MnO3 (SSMO) has been reported to have a highly-correlated electronic system for e g -electrons in a Mn ion. According to the previous studies, the C-type orbital-ordered (COO) state with the I4/mcm symmetry was found to be formed from the disordered-cubic (DC) state on cooling. The feature of the COO state is that its crystal structure involves both the Jahn-Teller distortion to orbital ordering and the R 25 -type rotational displacement of oxygen octahedra. Because of the involvement of both the distortion and the displacement, their competition should be expected in the formation of the COO state. However, the detailed features of the competition have not been understood yet. Thus, the crystallographic features of the COO state in SSMO have been examined by x-ray powder diffraction and transmission electron microscopy. It was found that, when the Sm content increased from x = 0 at room temperature, the DC state changed into the COO state with the tetragonal symmetry around x = 0.13. The notable feature of the COO state is that the state is characterized by a nanometer-scaled banded structure consisting of an alternating array of two tetragonal bands. One tetragonal band consisted of the COO state involving both the Jahn-Teller distortion and the R 25 -type rotational displacement. But, there was only the latter displacement in the other, the state of which could be identified as a disordered tetragonal (DT) state. Based on this, it is understood that the COO-state formation from the DC state should take place via the appearance of the DT state, which may involve fluctuations of the C-type orbital ordering.

The multiferroic material YbMnO3 has been reported to exhibit both ferroelectric and antiferromagnetic orders in the ground state. Of these two orders, the ferroelectric order is associated with the P63/mmc-to-P63cm structural transition, which occurs around 1270 K. The interesting feature of the ferroelectric state is that a cloverleaf domain structure with a pseudo-six-fold symmetry is observed in transmission electron microscopy images with the beam incidence parallel to the hexagonal axis. To understand the origin of the formation of the cloverleaf domain structure, we have examined the crystallographic features of the ferroelectric state in YbMnO3 by transmission electron microscopy. In this study, particularly, we adopted the experimental condition that electron beam incidences are perpendicular to the hexagonal axis. It was, as a result, found that there existed various ferroelectric domain structures including the cloverleaf domain structure under the present condition. The notable feature of domain structures found in this study is that each domain structure basically consists of six domains, whose domain boundaries are terminated at one point. Because this feature makes us reminiscent of a discommensurate structure in an incommensurate state, we took high-resolution electron micrographs of areas including domain boundaries. Their analysis indicated that a domain boundary could be identified as a discommensuration with a phase slip of π/3. It is thus understood that the cloverleaf domain structure should be one of domain morphologies for a discommensurate structure, which is related to the break of the translational symmetry.

To understand the formation of the Bergman cluster in the F-type icosahedral quasicrystal, crystallographic relations between the quasicrystal and the intermetallic-compound H and Zn$_{23}$Y$_6$ phases in the Zn-Mg-Y alloy system were investigated mainly by transmission electron microscopy. It was found that, although sample rotations of about 1{\deg} were required to obtain simple crystallographic relations, the orientation relationship was established among the cubic-$Fm\overline{3}m$ Zn$_{23}$Y$_6$ structure, the hexagonal-$P6_3/mmc$ H structure, and the F-type icosahedral quasicrystal (IQ); that is, $[\overline{1}13]_{\rm c}$ // the fivefold axis in the IQ // N$(2\overline{1} \overline{1}0)_{\rm H}$, and $[110]_{\rm c}$ // the twofold axis in the IQ // N$(05\overline{5}3)_{\rm H}$, where N(hkml)$_{\rm H}$ means the normal direction of the (hkml)$_{\rm H}$ plane in the H structure. The correspondences between atomic positions in the Bergman cluster and in the Zn$_{23}$Y$_6$ structure and between those in the cluster and in the H structure were investigated on the basis of the established relationship. As a result, an assembly of six short-penetrated-decagonal columns was identified as an appropriate nucleus in the formation of the Bergman cluster from these two structures., Comment: 29 pages, 8 figures

The relaxor state has been found in the mixed ferroelectric system Ba (Ti1-xZrx)O3 around x = 0.35. To understand the nature of the relaxor state, the crystallographic features of the paraelectric (PC), ferroelectric, and relaxor states for 0.15 ≤ x ≤ 0.40 have been investigated mainly by transmission electron microscopy. It was found that a microstructure of the ferroelectric state for 0.15 ≤ x ≤ 0.28 consisted of banded structures with boundaries parallel to the {110}PC and {100}PC planes. Based on the Sapriel theory concerning ferroelastic transitions, it was understood that the banded structures were consistent with domain structures in the ferroelectric rhombohedral (FR) state having a polarization vector parallel to one of the PC directions. With the help of the failure of Friedel’s law in diffraction, furthermore, polar regions having PC and PC components of a PC polarization vector were also found to be separately observed in the PC and relaxor states as well as the FR state. Then, in-situ observation for 0.29 ≤ x ≤ 0.40 made in this study indicated that the PC and relaxor states consisted of polar nanometer-sized regions having these two components. Based on this, the relaxor state in BTZ can be identified as an assembly of polar nanometer-sized regions, which were produced by the suppression of the (PC→FR) ferroelectric transition on cooling.

There exists the orbital-modulated (OM) state in the layered manganite Ca2-xNdxMnO4 (CNMO) with 0.20 ≤ x ≤ 0.50. To understand the effect of the tilting of MnO6 octahedra to the stability of the OM state, the crystallographic features of CNMO samples prepared by a solid-state reaction have been investigated mainly by transmission electron microscopy. For 0.30 ≤ x ≤ 0.50, it was found that the (LTO → Pccn/LTT) structural transition occurred on cooling from room temperature, where the LTO and Pccn/LTT structures are, respectively, characterized by tilting displacements of oxygen octahedra about one and two of the directions. The notable feature of the (LTO → Pccn/LTT) transition is that its progress strongly suppresses the growth of the OM state for 0.30 ≤ x ≤ 0.45. As a result of the suppression, the OM state exhibits a re-entrant behavior for its appearance. This is an indication that the Pccn/LTT tilting is not favorable for the stabilization of the OM state.

In the highly-correlated electronic system Sr1-xNdxMnO3, the C-type orbital-ordered (COO) state is present for 0.15

The charge-exchange-type orbital-ordered (CEOO) state accompanying antiferromagnetic ordering has been reported in the highly-correlated electronic system Ca1-xPrxMnO3 (CPMO) with the simple perovskite structure. The feature of the CEOO state in CPMO is that the state is present in the wide Pr-content range of 0.30 ≤ x ≤ 0.70. Although the Zener-polaron model was proposed for the CEOO state at x = 0.60, the detailed features of the CEOO state, particularly for lower Pr contents, have not been understood sufficiently. We have thus investigated the crystallographic features of the CEOO state in CPMO with 0.40 ≤ x ≤ 0.50, mainly by transmission electron microscopy. It was found that, when the temperature was lowered from the disordered state, incommensurate satellite reflections characterizing the CEOO state appeared in electron diffraction patterns below about 250 K in CPMO. The careful analysis of the reflections indicated that the CEOO state for 0.40 ≤ x ≤ 0.45 was different from that for 0.45 ≤ x ≤ 0.50. Concretely, the former CEOO state accompanied only a transverse lattice modulation, while both transverse and longitudinal modulations with different wave vectors appeared in the latter state. This implies that the state for 0.40 ≤ x ≤ 0.45 can be regarded as an orbital-modulated (OM) state without a charge modulation. It is thus understood that an increase in the Pr content leads to the OM-to-CEOO state change below about 250 K around x = 0.45.

In the Mn-Si alloy system, there is the intermetallic-compound ν phase around Mn-18at.%Si. Its crystal structure called the ν structure has been reported to involve complex coordination polyhedra with coordination numbers (CN’s) 12, 14, and others. To clarify whether one of these polyhedra can be identified as a structural unit or not in the ν structure, we have investigated the crystallographic features of the (R → R + ν) reaction in Mn-15at.%Si alloy samples by transmission electron microscopy. In Mn-15at.%Si samples obtained by cooling from the single R phase at a relatively fast cooling rate, metastable precipitates were found to be present in the R-structure matrix. Their notable feature is that each precipitate involves regions exhibiting characteristic electron diffraction patterns, which indicate the presence of metastable states, in addition to the initial amorphous and final ν states. Based on the careful analysis of these patterns, it was understood that the metastable states were directly associated with the formation of the ν structure, and that the formation started with the appearance of dodecagonal atomic columns. Because a dodecagonal column is characterized by a one-dimensional array of CN14 polyhedra, among the coordination polyhedra involved in the ν structure, a CN14 polyhedron can be identified as its structural unit.

The simple perovskite manganite Sr1-xCexMnO3 (SCMO) has a highly-correlated electronic system with a three-dimensional character. Because the presence of orbital-ordered states of eg electrons can be expected in SCMO, the crystallographic features of SCMO samples with 0.09 ≤ x ≤ 0.20 have been investigated mainly by transmission electron microscopy. In addition to fundamental reflections due to the simple perovskite structure, their electron diffraction patterns at room temperature exhibited both the presence of superlattice reflections at k = ()c in the cubic notation and the splitting of fundamental and superlattice reflections. The careful analysis of these reflections indicated that the superlattice reflections originated from the R25-type rotational displacement of oxygen octahedra about one of the c directions. On the other hand, the splitting of the reflections was found to be due to a {110}c banded structure consisting of two tetragonal bands with different c/a values. Because one of two tetragonal bands had the c/a value of about 1.028, the splitting reflects the introduction of the Jahn-Teller distortion as a response of a lattice system to orbital ordering. It is thus understood that the C-type orbital ordering of eg electrons should be involved in the state at room temperature for 0.09 ≤ x ≤ 0.20 in SCMO.

In the ferroelectric mixed-oxide system Ba(Ti1−xZrx)O3 (BTZ), an increase in Zr content results in the crossover from the ferroelectric MA-type state with monoclinic symmetry to the relaxor state around x = 0.28. As a result of the crossover, BTZ is identified as the relaxor for x > 0.28. To understand the nature of the relaxor in BTZ, direct observations of the paraelectric (PE), MA, and relaxor states for 0.17 ≤ x ≤ 0.40 was carried out between 400 K and 87 K by transmission electron microscopy with the help of the failure of Friedel's law. The observations indicated that polar nanometer-sized regions with PE and PE components were separately observed in the PE state above both Tc and Tm , which are, respectively, a transition temperature of the direct (PE→MA) transition and a maximum temperature of the real dielectric permittivity for the relaxor. During cooling from the paraelectric state above Tm in the relaxor, in the relaxor state below it, PC-component regions locally formed a 180° ...

The crystallographic features of Bi1−xCaxFeO3 samples with x = 0.10, 0.15, 0.20, and 0.30 compositions are investigated by transmission electron microscopy. Perovskite-based modulated structures ar...

To understand the crystallographic relation between the Bergman-type icosahedral quasicrystal and its approximant-T structure, we have investigated the crystallographic features of prepared Zn-Mg-Al alloy samples, mainly by transmission electron microscopy. It was found that there existed three kinds of regions: that is, C14-Laves, approximant-T, and icosahedral-quasicrystal regions, in Zn-Mg-Al alloy samples with the composition of Zn-36at.%Mg-9at.%Al. Among these regions, in particular, we tried to determine an orientation relationship between neighboring icosahedral-quasicrystal and approximant-T regions. Based on the determined relationship, for instance, four threefold rotatory-inversion axes in the T structure were found to be parallel to four of ten threefold rotatory-inversion axes in the icosahedral quasicrystal. It was thus understood that the atomic arrangements of the Bergman-type icosahedral quasicrystal and its approximant-T structure are likely to resemble each other.

The electronic states of Sr1-xNdxMnO3 with the simple perovskite structure are characterized by a three-dimensional highly-correlated electronic system. To understand the detailed features of the A-and CE-type antiferromagnetic states in this system, their crystallographic features for x = 0.47, 0.48, and 0.50 have been investigated mainly by both x-ray powder diffraction and transmission electron microscopy. It was found at room temperature that the crystal structure for x = 0.47 was determined to have the monoclinic C2/m symmetry, while the orthorhombic Imma structure was confirmed for x = 0.48 and 0.50. The in-situ observation for x = 0.47 indicated that, in the heating process from room temperature, the C2/m-to-Imma transition occurred in the paramagnetic state, and that the A-type antiferromagnetic state appeared below about 200 K on cooling. In addition, the cooling from room temperature for x = 0.48 and 0.50 resulted in the direct transitions from the orthorhombic Imma state to the A-and CE-type antiferromagnetic states, respectively. Based on these features, we simply discussed the physical origin of the appearance of the paramagnetic state with the monoclinic symmetry for x = 0.47.

The mixed-oxide system Ba (Ti1-xZrx)O3 (BTZ) with the simple perovskite structure was reported to exhibit the remarkable dielectric response around x = 0.08. In order to understand the origin of the response, we have investigated the crystallographic features of ferroelectric states in BTZ with 0 ≤ x ≤ 0.15 mainly by transmission electron microscopy. According to the constructed phase diagram of BTZ, when the Zr content increases from x = 0 around 300 K, the ferroelectric tetragonal state in BaTiO3 is changed into the ferroelectric orthorhombic state around x = 0.03, and then into the ferroelectric monoclinic state around x = 0.06. That is, the monoclinic state with a polarization vector in the {110}PC planes is present in BTZ with 0.07 ≤ x ≤ 0.15, where the subscript PC denotes the paraelectric cubic state. The notable feature of the monoclinic state is that it exhibits the herringbone-type domain structure consisting of nanometer-sized ferroelectric domains. It is thus understood that the remarkable dielectric response in BTZ should be associated with the presence of nanometer-sized domains with the monoclinic symmetry.

To understand a stability of the orbital-modulated (OM) state in Sr2-xRxMnO4 (R = Pr, Nd), the crystallographic features of oxide samples with 0.20 < x ≤ 0.50, prepared by the coprecipitation technique, have been investigated by transmission electron microscopy. When the Pr content x corresponding to the eg-electron concentration increased from x = 0, the OM state appeared in 0.20 < x ≤ 0.40 as a neighboring state of an orbital ordered (OO) state around x = 0.20. The interesting features are that around x = 0.44 there is a nanometer-sized coexisting state consisting of the OM and disordered tetragonal (DT) states, and that an average size of OM-state regions in the coexisting state decreases with increasing the eg-electron concentration. In addition, the so-called CE-type antiferromagnetic state found in Sr1.5La0.5MnO4 is absent in the Nd and Pr cases. This suggests that the stability of the OM state is not directly associated with charge ordering of eg electrons, but basically due to only their orbital ordering.

To understand dielectric properties around the ferroelectric tetragonal (FT)/rhombohedral (FR) phase boundary in Pb1-xLax(Zr1-yTiy)O3, the crystallographic features of ferroelectric states around the boundary have been investigated by transmission electron microscopy. It was found that, when the Ti content approached to the phase boundary in the FT-phase area, a dielectric property became the relaxor behavior. The corresponding change in the crystallographic features is that the usual FT state is converted into the nanometer-sized coexisting state of the ferroelectric monoclinic (FM) and FR phases. Because the crystal structure of FR-phase regions in the coexisting state involves the R25-type rotational displacement of oxygen octahedra, the FR phase can be identified as the low-temperature ferroelectric rhombohedral phase that is present in Pb(Zr1-yTiy)O3. It is thus understood that the relaxor behavior found in Pb1-xLax(Zr1-yTiy)O3 should be associated with the presence of the nanometer-sized coexisting state that consists of two ferroelectric phases.

The purpose of this work was to evaluate the short-term results of laparoscopic-assisted limited liver resection.We analyzed the clinical outcome in 17 patients (mean age 70 +/- 8 years) who had undergone laparoscopic-assisted limited liver resection from March 2006 to December 2008. Preoperative diagnoses were HCC in 13 patients and metastasis of colon cancer in 4. The operation consisted of laparoscopic mobilization of the target liver lobe, followed by open liver resection through a 7- to 10-cm extraction site.Mean tumor size was 3.0 +/- 1.1 cm (range 1.2-5 cm). The mean operative time was 362 +/- 85 min. The mean blood loss was 451 +/- 413 ml, and no blood transfusion was required in any patient. There were no intraoperative complications, and conversion to laparotomy was needed in one case. Postoperative complications developed in 4 cases (4 infections, 24%), all of which were improved by conservative management. However, there was no postoperative mortality. None of the patients had any peritoneal carcinomatosis or port-site or resection site recurrence during a mean follow-up of 18 +/- 9.6 months. According to the analysis of the tumor location, the criterion for an adequate tumor location in the right lobe for this operation was set with the tumor at a distance of more than 5 cm from the inferior vena cava and the root of the hepatic vein (5 cm rule).Laparoscopic-assisted limited liver resection is feasible and well tolerated. Accumulation of more data may be needed for evaluation of long-term outcome.

The structural correspondence among the bcc, ordered-bcc B2, triclinic Al2Fe and approximant Al5Fe2 structures have been examined on the basis of the experimentally obtained orientation relationship of and , where N(hkl) denotes the normal direction of the (hkl) plane. The formation of the triclinic Al2Fe structure from the bcc structure is directly associated with that of Al–Fe covalent bonds; that is, hybridization between Al and Fe atoms. The covalent bond formation results in the appearance of decagonal-like atomic arrangements in the Al2Fe structure, which are similar to those in the approximant Al5Fe2 structure.

The electronic system in the layered perovskite Sr2−xNdxMnO4 is characterized as a two-dimensional eg-electron system. In order to understand the stability of electronic states in the Nd-content region of 0 ⩽ x ⩽ 0.50, the crystallographic features of this manganite have been investigated by transmission electron microscopy. The increase in the Nd-content led to the orbital ordered state in 0.10 ⩽ x ⩽ 0.25 and the charge and orbital ordered state in 0.25 ⩽ x 0.35.

Congenital Morgagni hernia is a rare clinical condition. We present a 72-year-old man with epigastric discomfort and hematemesis who was diagnosed with hernia of Morgagni with an incarceration of the stomach and colon. The patient was treated electively by laparoscopic composite-mesh repair without excising the hernial sac or approximating the edges of the defect, which was 10 × 6 cm in diameter. He was discharged on the seventh postoperative day without any complications. At a 1-year follow-up examination he had no recurrence nor clinical symptoms, although the large hernial sac contained fluid. Laparoscopic composite-mesh repair is a less-invasive and tension-free method for Morgagni hernia that results in an excellent clinical outcome.

In (1-x)Pb(Zn 1/3 Nb 2/3 )O 3 -xPbTiO 3 (PZN-xPT), there exists the morphotropic phase boundary (MPB) as an almost temperature-independent boundary around x = 0.10. In order to understand an origin of the excellent piezoelectric response found near the MPB in PZN-xPT, the features of ferroelectric domain structures in the tetragonal side of the MPB have been examined mainly by transmission electron microscopy. The ferroelectric domain structure in x = 0.12 specimens prepared from single crystals as bulk samples was found to be the superposition of the tetragonal domain structure with the [001] polarization and the curved-boundary regions with the [100] or [010] one. On the other hand, the cooling from the paraelectric phase in thin specimens used for transmission-electron-microscopy observation resulted in two types of ferroelectric domain structures. One was the fine {110} banded structure in the fast cooling rate and the other was the maze-pattern structure in the slow rate. These two structures usually...

We have investigated microstructures related to anomalous ferroelectric properties such as the magnetocapacitance effect in magnetic ferroelectric compounds YMn 1 − x Ti x O 3 and (Y,A)Mn 0.825 Ti 0.175 O 3 (A = La, Ca, Zr) mainly by the transmission electron microscopy. It is found that the size of the ferroelectric domains in YMn 1 − x Ti x O 3 depends strongly on the Ti concentration (x) and the size is estimated to be about 10–20 nm in the x = 0.175 compound. In addition, structural change from the ferroelectric P6 3 cm phase to the rhombohedral one was found in the x = 0.40 compound. On the other hand, characteristic diffuse scattering elongating along both the [001] and [110] direction was found in (Y,Zr)Mn 0.825 Ti 0.175 O 3 , which is similar to that found in the x = 0.175 compound. It is revealed that the partial substitution in YMnO 3 breaks the long-ranged FE ordering and structural fluctuation is induced, which should be responsible for the anomalous FE behaviors in these compounds.

The influence of antiphase boundaries (APBs) on the kinetic process of the L12 → D022 structural change in an Ni3Al0.45V0.50 alloy has been investigated by transmission electron microscopy. The structural change includes two kinetic factors, i.e., the periodic introduction of antiphase-shifted planes (APSPs) in the L12 structure and V diffusion in the L12 matrix. Our results revealed that APB migration was accompanied by V diffusion as if to sweep the V atoms out of the antiphase domains (APDs). It was also found that the APBs served as the nucleation sites of the D022 regions, because the combination of the migrated APBs produced the APSPs in the L12 structure. On this basis, it is proposed that the APBs bring together the two kinetic factors in the process of the L12 → D022 structural change, the physical origin of which is the variation in the charge density distribution of the APDs due to APB migration.

The microstructure evolution related to the L1 2 (supersaturated Ni 3 Al 1-x V x ) → L1 2 (Ni 3 Al)+D0 22 (Ni 3 V) phase separation of the Ni 3 Al 0.50 V 0.50 alloy, with the addition of a small amount of Si (less than 0.2 mol%), was examined by transmission electron microscopy. The data showed that the L1 2 single phase was formed via the appearance and subsequent disappearance of the D0 22 regions under an isothermally holding process, as in the case of the Ni 3 Al 0.50 V 0.50 alloy without Si. A striking feature of the microstructure evolution of the present alloy was that the formation of the final L1 2 single phase was accomplished within an extremely brief period of less than 10min. Such a brief period indicated that the microstructure evolution was not accompanied by atomic diffusion, which was quite different from the case of the Si-free alloy. On this basis, we propose that the Si addition induced a pinning effect on atomic migration (i.e., suppression of long-range atomic diffusion) in the supersaturated L1 2 matrix and thus accelerated the formation of the final L1 2 single phase.

The evolution of states related to D022 precipitation in the supersaturated L12 matrix to form the L12+D022 equilibrium state of the Ni3Al1−xVx (0.40≤x≤0.60) alloy system was examined by transmission electron microscopy. Our results revealed that the microstructure of the initial L12 single state varied with the change in the alloy composition and that such a variation caused a bifurcation of the final states, i.e., the L12+D022 equilibrium state (x = 0.40 and x≥0.55) and the metastable L12 single state (0.40

It has been found that phase separation, i.e., D0 22 precipitation in the supersaturated L1 2 matrix to form the L1 2 + D0 22 equilibrium state, stagnates in the Ni 3 Al 0.5 2V 0.48 alloy under a certain thermodynamic condition. This stagnation originates from the suppression of the long-range vanadium diffusion in the L1 2 matrix, so-called diffusion blocking. Because diffusion blocking is inherent to the L1 2 structure, its occurrence depends largely on the morphological features of the L12 matrix. In this study, the microstructure evolution during the phase separation of the Ni 3 Al 0.40 V 0.60 alloy was examined from the viewpoint of the relation between the variation in the initial microstructure and the appearance of the effect of diffusion blocking. Our results showed that cuboidal domains of about 30 nm on a side formed in the initial L1 2 matrix and that the D0 22 regions appeared at the domain boundaries. The microstructure evolution of the alloy was found to proceed via the rearrangement, combination, and growth of these D0 22 regions, accompanying vanadium migration of about 20 nm in the L1 2 matrix. The requisite migration length was determined by the size and density of the initial D0 22 regions, which depend on the size of the L1 2 cuboidal domains. A shorter migration length than that in the case of the Ni 3 Al 0.52 V 0.48 alloy was presumed to be advantageous to concealing the effect of diffusion blocking. On that basis, it was concluded that the occurrence of the phase separation in the Ni 3 Al 0.40 V 0.60 alloy was attributed to the reduction in the size of the cuboidal domains in the initial L1 2 matrix.

The crystallographic features of the simple perovskite oxides La 1 − x Sr x MnO 3 with 0⩽ x ⩽0.08, which are known to be correlated-electron insulators, have been examined by X-ray powder diffraction and transmission electron microscopy. It was confirmed on the basis of the powder diffraction profiles obtained that the orthorhombic-to-monoclinic structural phase transition took place; for instance, at 500 K in the x =0.08 sample. The profiles also indicated that the structural transition accompanied the introduction of the Jahn–Teller distortion and the increase in both the orthorhombic distortion and the A-site-ion displacement. Based on the reciprocal lattices determined from electron diffraction patterns, further, it was found that these distortions and displacement never resulted in the change in the extinction rule of diffraction spots, and that the monoclinic distortion was actually involved in the low-temperature phase. That is, the structural phase transition can basically be regarded as a ferroelastic transition in terms of the lowering of the symmetry.

症例は83歳,女性.平成14年7月,直腸癌に対し低位前方切除術およびリンパ節郭清(D3)を施行した.術前の腹部CTで左副腎に内部が不均一に造影される3cm大の腫瘤を認めたが内分泌検査で異常を認めず,内分泌非活性腺腫を疑い,左副腎腫瘍に関しては経過観察とした.術後6カ月目に全身検索を目的に再入院となったが,腹部CTで左副腎の腫瘍は3.5cm大と軽度増大し,肝S7に1.5cm大の腫瘍を認めた.直腸癌術後肝転移,左副腎転移と診断し左副腎全摘,肝右葉切除術を施行した.副腎腫瘍は最大径35mm,肝腫瘍は18mmで,病理組織学的に副腎皮質癌の肝転移と診断された.再手術後8カ月目に多発性肝転移のため死亡した.副腎皮質癌は稀な疾患であるが自験例は腫瘍径35mmと非常に小さいにもかかわらず肝転移を認めたことから,副腎偶発腫瘍を認めた場合は副腎皮質癌も念頭において厳重な経過観察が必要と考えられた.