Robust Preparation of Sub-20-nm-Thin Lamellae for Aberration-Corrected Electron Microscopy

Aberration-corrected scanning transmission electron microscopy (STEM) has been advancing resolution, sensitivity, and microanalysis due to the intense demands of atomic-level microstructural investigations. Recent STEM technologies require preparing a thin lamella whose thickness is ideally below 20 nm. Although focused-ion-beam/scanning-electron-microscopy (FIB/SEM) is an established method to prepare a high-quality lamella, nanometer-level controllability of lamella thickness remains a fundamental problem. Here, the robust preparation of a sub-20-nm-thin lamella is demonstrated by FIB/SEM with real-time feedback from thickness quantification. The lamella thickness is quantified by back-scattered-electron SEM imaging in a thickness range between 0 and 100 nm without any reference to numerical simulation. Using real-time feedback from the thickness quantification, the FIB/SEM terminates thinning a lamella at a targeted thickness. The real-time feedback system eventually provides 1-nm-level controllability of the lamella thickness. As a proof-of-concept, a near-10-nm-thin lamella is prepared from a SrTiO3 crystal by our methodology. Moreover, the lamella thickness is controllable at a target heterointerface. Thus, a sub-20-nm-thin lamella is prepared from a LaAlO3 /SrTiO3 heterointerface. The methodology offers a robust and operator-independent platform to prepare a sub-20-nm-thin lamella from various materials. This platform will broadly impact aberration-corrected STEM studies in materials science and the semiconductor industry.

Epitaxy and transport properties of alkali-earth palladate thin films

Topological insulators and semimetals are an interesting class of materials for new electronic and optical applications owing to their characteristic electromagnetic responses originating from the spin-orbit coupled band structures. However, topological electronic structures are rare in oxide materials despite their chemical stability being preferable for applications. In this study, given the theoretical prediction of Dirac bands in CaPd3O4, we investigate the fabrication and transport properties of SrPd3O4 and CaPd3O4 thin films as candidates of oxide Dirac semimetals. We have found that these materials are epitaxially grown on MgO (100) substrate under limited growth conditions by pulsed laser deposition. The transport properties show a weak temperature dependence, suggestive of narrow-gap properties, although unintentionally doped holes hinder us from revealing the presence of the Dirac band. Our study establishes the basic thermodynamics of thin-film fabrication of these materials and will lead to interesting properties characteristic of topological band structure by modulating the electronic structure by, for example, chemical substitutions or pressure.

Competing correlated states around the zero-field Wigner crystallization transition of electrons in two dimensions

The competition between kinetic energy and Coulomb interactions in electronic systems leads to complex many-body ground states with competing orders. Here we present zinc oxide-based two-dimensional electron systems as a high-mobility system to study the low-temperature phases of strongly interacting electrons. An analysis of the electronic transport provides evidence for competing correlated metallic and insulating states with varying degrees of spin polarization. Some features bear quantitative resemblance to quantum Monte Carlo simulation results, including the transition point from the paramagnetic Fermi liquid to Wigner crystal and the absence of a Stoner transition. At very low temperatures, we resolve a non-monotonic spin polarizability of electrons across the phase transition, pointing towards a low spin phase of electrons, and a two-order-of-magnitude positive magnetoresistance that is challenging to understand within traditional metallic transport paradigms. This work establishes zinc oxide as a platform for studying strongly correlated electrons in two dimensions.

Clinical usefulness of a novel fluorescence technique for the intraoperative diagnosis of surgical margins in patients with breast cancer

In both 5- and 15-min data, FI was significantly higher in malignant tissues than in benign tissues. The diagnostic accuracy was similar at 5 and 15 min. Therefore, the 5-min FI was enough applying in the further analyses.

Observation of Nonlinear Spin-Charge Conversion in the Thin Film of Nominally Centrosymmetric Dirac Semimetal SrIrO_{3} at Room Temperature

Spin-charge conversion via spin-orbit interaction is one of the core concepts in the current spintronics research. The efficiency of the interconversion between charge and spin current is estimated based on Berry curvature of Bloch wave function in the linear-response regime. Beyond the linear regime, nonlinear spin-charge conversion in the higher-order electric field terms has recently been demonstrated in noncentrosymmetric materials with nontrivial spin texture in the momentum space. Here, we report the observation of the nonlinear charge-spin conversion in a nominally centrosymmetric oxide material SrIrO_{3} by breaking inversion symmetry at the interface. A large second-order magnetoelectric coefficient is observed at room temperature because of the antisymmetric spin-orbit interaction at the interface of Dirac semimetallic bands, which is subject to the symmetry constraint of the substrates. Our study suggests that nonlinear spin-charge conversion can be induced in many materials with strong spin-orbit interaction at the interface by breaking the local inversion symmetry to give rise to spin splitting in otherwise spin degenerate systems.

Interplay of spin-orbit coupling and Coulomb interaction in ZnO-based electron system

Spin-orbit coupling (SOC) is pivotal for various fundamental spin-dependent phenomena in solids and their technological applications. In semiconductors, these phenomena have been so far studied in relatively weak electron-electron interaction regimes, where the single electron picture holds. However, SOC can profoundly compete against Coulomb interaction, which could lead to the emergence of unconventional electronic phases. Since SOC depends on the electric field in the crystal including contributions of itinerant electrons, electron-electron interactions can modify this coupling. Here we demonstrate the emergence of the SOC effect in a high-mobility two-dimensional electron system in a simple band structure MgZnO/ZnO semiconductor. This electron system also features strong electron-electron interaction effects. By changing the carrier density with Mg-content, we tune the SOC strength and achieve its interplay with electron-electron interaction. These systems pave a way to emergent spintronic phenomena in strong electron correlation regimes and to the formation of quasiparticles with the electron spin strongly coupled to the density.

P224 Valvuloplasty treatment and three-dimensional analysis for isolated cleft of the anterior mitral valve leaflet: a case report

Introduction: Isolated cleft of the anterior mitral valve leaflet is a very rare congenital disease and a cause of mitral regurgitation

not associated with atrioventricular septal defect. In this case, we report our experience in valvuloplasty treatment for mitral regurgitation with this rare aetiology.

Case description

23-year-old Russian women. Although cardiac murmur was pointed out in her childhood and she was diagnosed as mitral regurgitation, she refused treatment. After getting married with a Japanese man and moving to Japan, her symptoms had worsened and she visited our hospital for treatment. Preoperative transthoracic echocardiography (TTE) had indicated the regurgitation from the central part of the mitral valve. Preoperative transoesophageal echocardiography (TOE) had pointed out the isolated cleft of the anterior mitral valve.

Surgical mitral valvuloplasty was scheduled, and the TOE after anaesthetic induction showed the isolated cleft of the anterior mitral valve the same as in the preoperative period and pointed out the posterior leaflet billowing. The operative finding was also similar to TOE: the largely bisected central anterior mitral valve and billowing, P2 billowing, shortening of P1 and P3, P2-3 cleft. There were no chords at the anterior cleft. The valvuloplasty was performed including five-time pump runs in total: 1) Continuous suture for the anterior cleft and ring annuloplasty were performed, and the regurgitation was seemed to be almost controlled at the water-leak test and the ink test; 2) Artificial chordae and leaflet plications were added to residual regurgitation from the posterior region; 3)The residual regurgitation was controlled to Mild but it became a lateral jet toward the ring; 4)Mild remnant flow was pointed out: the regurgitation seemed to be from the posterior cleft, where immediately below the ring suture; 5) Pericardium patch was added and the remnant flow was almost eliminated. The pump was weaned and the operation was finished without any problems.

Discussion

The cause of difficulty in this valvuloplasty was thought to be caused by the difficulty in evaluating the mitral valve morphology. It was evident that the anterior leaflet of the mitral valve was largely bisected. However, it was difficult to evaluate the coaptation line and area due to the absence of chordal cords in the anterior cleft and the billowing or shortening of the posterior leaflet. Although preoperative three-dimensional analysis helped evaluating the isolated cleft and the regurgitation was almost controlled in the evaluation in the operation field, nevertheless, a residual regurgitation occurred and indicated in the TOE after re-beating.

Conclusion

It is important and necessary to use fine evaluation of coaptation is needed in valvuloplasty for isolated cleft of the anterior mitral valve leaflet; not only apply three-dimensional analysis but also apply two-dimensional echocardiogram.

Abstract P224 Figure.

P662 Synchrony between the right and left heart systems is recovered after TAVI in patients with severe aortic stenosis

Funding Acknowledgements

Young Investigator Grant of Japanese Society of Cardiovascular Anesthesia

Background / Introduction

Evidences have shown that cardiac function decline and systolic phase change are caused by massive afterload of the stenosed aortic valve in patients with severe aortic valve stenosis. As a result of the reduction of the left ventricular afterload by valve replacement, the cardiac function recovers. However, it has not been clarified yet how the changes in cardiac function affect the relationship between the right and left heart systems, as well as the systole phase.

TAPSE and MAPSE are known as indices of simple cardiac function evaluation by measuring the movement distance of the atrioventricular annulus. We obtained these indices (i.e. TAPSE, MAPSE) within the same heartbeat using speckle tracking analysis of the atrioventricular annulus and evaluated the changes in cardiac function and phase between the right and left heart systems.

Purpose

To reveal the relationship of cardiac function and time phase between the right and left heart systems by evaluating the maximum movement distance and time of the atrioventricular annulus within the same heartbeat and the same view in patients with severe aortic valve stenosis before and after TAVI.

Methods

A prospective cohort study was conducted. We recruited and analyzed 44 patients with severe aortic valve stenosis who received TAVI treatment, able to record baseline before treatment and follow-up 6 months and 12 months after treatment at our hospital from March 2017 to May 2019. Patients were excluded if more than 2 degree of atrioventricular valve regurgitation or incomplete data. The apical four-chamber view was used for speckle tracking analysis with the origin of the apical extension and region of interest (ROI) of the mitral annulus and tricuspid annulus. For each patient before treatment, at 6 months and 12 months after treatment, the maximum contraction distance (DM), maximum contraction time (TM) of the mitral valve annulus, maximum contraction distance (DT) and maximum contraction time (TT) of the tricuspid annulus were measured. Maximum contraction distance ratio (DM/ DT) and maximum contraction time ratio (TM/ TT) were calculated. For statistical analysis, t-test and ANOVA were used, and a significance threshold of p <0.05 was applied.

Results

TM/ TT decreased at 12 months after TAVI, and DM/ DT increased significantly at 6 months and 12 months after TAVI when compared to baseline before treatment.

Conclusions

In patients with severe aortic valve stenosis, the correction of cardiac function difference between the right and left heart systems occurs from 6 months after TAVI. Moreover, the correction of contraction phase difference between the right and left heart systems at 12 months after TAVI. Thus, the synchrony between the right and left heart system is recovered 12 months after TAVI.

Abstract P662 Figure.

Composite fermion liquid to Wigner solid transition in the lowest Landau level of zinc oxide

Interactions between the constituents of a condensed matter system can drive it through a plethora of different phases due to many-body effects. A prominent platform for it is a dilute two-dimensional electron system in a magnetic field, which evolves intricately through various gaseous, liquid and solid phases governed by Coulomb interaction. Here we report on the experimental observation of a phase transition between the composite fermion liquid and adjacent magnetic field induced phase with a character of Wigner solid. The experiments are performed in the lowest Landau level of a MgZnO/ZnO two-dimensional electron system with attributes of both a liquid and a solid. An in-plane magnetic field component applied on top of the perpendicular magnetic field extends the Wigner-like phase further into the composite fermion liquid phase region. Our observations indicate the direct competition between a composite fermion liquid and a Wigner solid formed either by electrons or composite fermions.

In two-dimensional electron systems, strong Coulomb interactions lead to the formation of new phases. Here the authors observe a transition between two of these correlated phases, a composite fermion liquid and Wigner solid, in a zinc oxide heterostructure.

A cascade of phase transitions in an orbitally mixed half-filled Landau level

Half-filled Landau levels host an emergent Fermi liquid that displays instability toward pairing, culminating in a gapped even-denominator fractional quantum Hall ground state. While this pairing may be probed by tuning the polarization of carriers in competing orbital and spin degrees of freedom, sufficiently high quality platforms offering such tunability remain few. We explore the ground states at filling factor ν = 5/2 in ZnO-based two-dimensional electron systems through a forced intersection of opposing spin branches of Landau levels taking quantum numbers N = 1 and 0. We reveal a cascade of phases with distinct magnetotransport features including a gapped phase polarized in the N = 1 level and a compressible phase in N = 0, along with an unexpected Fermi liquid, a second gapped, and a strongly anisotropic nematic-like phase at intermediate polarizations when the levels are near degeneracy. The phase diagram is produced by analyzing the proximity of the intersecting levels and highlights the excellent reproducibility and controllability that ZnO offers for exploring exotic fractionalized electronic phases.

Gate-tuned quantum Hall states in Dirac semimetal (Cd1-x Zn x )3As2

The recent discovery of topological Dirac semimetals (DSMs) has provoked intense curiosity not only regarding Weyl physics in solids but also about topological phase transitions originating from DSMs. One specific area of interest is controlling the dimensionality to realize two-dimensional quantum phases such as quantum Hall and quantum spin Hall states. For investigating these phases, the Fermi level is a key controlling parameter. From this perspective, we report the carrier density control of quantum Hall states realized in thin films of DSM Cd₃As₂. Chemical doping of Zn combined with electrostatic gating has enabled us to tune the carrier density both over a wide range and continuously, even across the charge neutrality point. Comprehensive analyses of gate-tuned quantum transport have revealed Landau-level formation from linearly dispersed sub-bands and its contribution to the quantum Hall states. Our findings also pave the way for investigating the low-energy physics near the Dirac points of DSMs.

Electric-field control of anomalous and topological Hall effects in oxide bilayer thin films

One of the key goals in spintronics is to tame the spin-orbit coupling (SOC) that links spin and motion of electrons, giving rise to intriguing magneto-transport properties in itinerant magnets. Prominent examples of such SOC-based phenomena are the anomalous and topological Hall effects. However, controlling them with electric fields has remained unachieved since an electric field tends to be screened in itinerant magnets. Here we demonstrate that both anomalous and topological Hall effects can be modulated by electric fields in oxide heterostructures consisting of ferromagnetic SrRuO₃ and nonmagnetic SrIrO₃. We observe a clear electric field effect only when SrIrO₃ is inserted between SrRuO₃ and a gate dielectric. Our results establish that strong SOC of nonmagnetic materials such as SrIrO₃ is essential in electrical tuning of these Hall effects and possibly other SOC-related phenomena.

Spintronic devices are typically controlled with magnetic fields or current injection but incorporating these mechanisms into high-density devices is difficult. Here the authors present an oxide device where the topological and anomalous Hall effects can instead be modulated using an electric field.

Quantum Hall states observed in thin films of Dirac semimetal Cd3As2

A well known semiconductor Cd₃As₂ has reentered the spotlight due to its unique electronic structure and quantum transport phenomena as a topological Dirac semimetal. For elucidating and controlling its topological quantum state, high-quality Cd₃As₂ thin films have been highly desired. Here we report the development of an elaborate growth technique of high-crystallinity and high-mobility Cd₃As₂ films with controlled thicknesses and the observation of quantum Hall effect dependent on the film thickness. With decreasing the film thickness to 10 nm, the quantum Hall states exhibit variations such as a change in the spin degeneracy reflecting the Dirac dispersion with a large Fermi velocity. Details of the electronic structure including subband splitting and gap opening are identified from the quantum transport depending on the confinement thickness, suggesting the presence of a two-dimensional topological insulating phase. The demonstration of quantum Hall states in our high-quality Cd₃As₂ films paves a road to study quantum transport and device application in topological Dirac semimetal and its derivative phases.

A magnetic heterostructure of topological insulators as a candidate for an axion insulator

The axion insulator which may exhibit an exotic quantized magnetoelectric effect is one of the most interesting quantum phases predicted for the three-dimensional topological insulator (TI). The axion insulator state is expected to show up in magnetically doped TIs with magnetizations pointing inwards and outwards from the respective surfaces. Towards the realization of the axion insulator, we here engineered a TI heterostructure in which magnetic ions (Cr) are modulation-doped only in the vicinity of the top and bottom surfaces of the TI ((Bi,Sb)₂Te₃) film. A separation layer between the two magnetic layers weakens interlayer coupling between them, enabling the magnetization reversal of individual layers. We demonstrate the realization of the axion insulator by observing a zero Hall plateau (ZHP) (where both the Hall and longitudinal conductivity become zero) in the electric transport properties, excluding the other possible origins for the ZHP. The manifestation of the axion insulator can lead to a new stage of research on novel magnetoelectric responses in topological matter.

Observation of anomalous Hall effect in a non-magnetic two-dimensional electron system

Anomalous Hall effect, a manifestation of Hall effect occurring in systems without time-reversal symmetry, has been mostly observed in ferromagnetically ordered materials. However, its realization in high-mobility two-dimensional electron system remains elusive, as the incorporation of magnetic moments deteriorates the device performance compared to non-doped structure. Here we observe systematic emergence of anomalous Hall effect in various MgZnO/ZnO heterostructures that exhibit quantum Hall effect. At low temperatures, our nominally non-magnetic heterostructures display an anomalous Hall effect response similar to that of a clean ferromagnetic metal, while keeping a large anomalous Hall effect angle θ_AHE≈20°. Such a behaviour is consistent with Giovannini-Kondo model in which the anomalous Hall effect arises from the skew scattering of electrons by localized paramagnetic centres. Our study unveils a new aspect of many-body interactions in two-dimensional electron systems and shows how the anomalous Hall effect can emerge in a non-magnetic system.

Evolution of Insulator-Metal Phase Transitions in Epitaxial Tungsten Oxide Films during Electrolyte-Gating

An interface between an oxide and an electrolyte gives rise to various processes as exemplified by electrostatic charge accumulation/depletion and electrochemical reactions such as intercalation/decalation under electric field. Here we directly compare typical device operations of those in electric double layer transistor geometry by adopting A-site vacant perovskite WO3 epitaxial thin films as a channel material and two different electrolytes as gating agent. In situ measurements of X-ray diffraction and channel resistance performed during the gating revealed that in both the cases WO3 thin film reaches a new metallic state through multiple phase transitions, accompanied by the change in out-of-plane lattice constant. Electrons are electrostatically accumulated from the interface side with an ionic liquid, while alkaline metal ions are more uniformly intercalated into the film with a polymer electrolyte. We systematically demonstrate this difference in the electrostatic and electrochemical processes, by comparing doped carrier density, lattice deformation behavior, and time constant of the phase transitions.

Observation of the quantum Hall effect in δ-doped SrTiO3

The quantum Hall effect is a macroscopic quantum phenomenon in a two-dimensional electron system. The two-dimensional electron system in SrTiO3 has sparked a great deal of interest, mainly because of the strong electron correlation effects expected from the 3d orbitals. Here we report the observation of the quantum Hall effect in a dilute La-doped SrTiO3-two-dimensional electron system, fabricated by metal organic molecular-beam epitaxy. The quantized Hall plateaus are found to be solely stemming from the low Landau levels with even integer-filling factors, ν=4 and 6 without any contribution from odd ν's. For ν=4, the corresponding plateau disappears on decreasing the carrier density. Such peculiar behaviours are proposed to be due to the crossing between the Landau levels originating from the two subbands composed of d orbitals with different effective masses. Our findings pave a way to explore unprecedented quantum phenomena in d-electron systems.

Thermal Generation of Spin Current in an Antiferromagnet

The longitudinal spin Seebeck effect has been investigated for a uniaxial antiferromagnetic insulator Cr(2)O(3), characterized by a spin-flop transition under magnetic field along the c axis. We have found that a temperature gradient applied normal to the Cr(2)O(3)/Pt interface induces inverse spin Hall voltage of spin-current origin in Pt, whose magnitude turns out to be always proportional to magnetization in Cr(2)O(3). The possible contribution of the anomalous Nernst effect is confirmed to be negligibly small. The above results establish that an antiferromagnetic spin wave can be an effective carrier of spin current.

Spin-Selective Electron Quantum Transport in Nonmagnetic MgZnO/ZnO Heterostructures

We report magnetotransport measurements on a high-mobility two-dimensional electron system at the nonmagnetic MgZnO/ZnO heterointerface showing distinct behavior for electrons with spin-up and spin-down orientations. The low-field Shubnikov-de Haas oscillations manifest alternating resistance peak heights which can be attributed to distinct scattering rates for different spin orientations. The tilt-field measurements at a half-integer filling factor reveal that the majority spins show usual diffusive behavior, i.e., peaks with the magnitude proportional to the index of the Landau level at the Fermi energy. By contrast, the minority spins develop "plateaus" with the magnitude of dissipative resistivity that is fairly independent of the Landau level index and is of the order of the zero-field resistivity.

Odd-parity magnetoresistance in pyrochlore iridate thin films with broken time-reversal symmetry

A new class of materials termed topological insulators have been intensively investigated due to their unique Dirac surface state carrying dissipationless edge spin currents. Recently, it has been theoretically proposed that the three dimensional analogue of this type of band structure, the Weyl Semimetal phase, is materialized in pyrochlore oxides with strong spin-orbit coupling, accompanied by all-in-all-out spin ordering. Here, we report on the fabrication and magnetotransport of Eu₂Ir₂O₇ single crystalline thin films. We reveal that one of the two degenerate all-in-all-out domain structures, which are connected by time-reversal operation, can be selectively formed by the polarity of the cooling magnetic field. Once formed, the domain is robust against an oppositely polarised magnetic field, as evidenced by an unusual odd field dependent term in the magnetoresistance and an anomalous term in the Hall resistance. Our findings pave the way for exploring the predicted novel quantum transport phenomenon at the surfaces/interfaces or magnetic domain walls of pyrochlore iridates.

Correlation-enhanced effective mass of two-dimensional electrons in Mg(x)Zn(1-x)O/ZnO heterostructures

We performed combined magnetotransport and cyclotron resonance experiments on two-dimensional electron systems confined in the Mg(x)Zn(1-x)O/ZnO heterostructures over a wide range of carrier densities, from 1.9 to 12 × 10(11) cm(-2) (3.5 </~ r(s) </~ 10, where r(s) is the Wigner-Seitz radius). As the carrier density was reduced, the transport mass m(tr)* was strongly enhanced. In marked contrast, the effective masses determined from the cyclotron resonance m(CR)(*) were found to be independent of the carrier density and as large as the bulk effective mass. The large enhancement of m(tr)(*), which exceeds m(CR)(*) by ~ 60%, at the lowest carrier density with r(s) 10 is purely attributed to the strong electron correlation.

Temperature-dependent magnetotransport around ν=1/2 in ZnO heterostructures

The sequence of prominent fractional quantum Hall states up to ν=5/11 around ν=1/2 in a high-mobility two-dimensional electron system confined at oxide heterointerface (ZnO) is analyzed in terms of the composite fermion model. The temperature dependence of R(xx) oscillations around ν=1/2 yields an estimation of the composite fermion effective mass, which increases linearly with the magnetic field. This mass is of similar value to an enhanced electron effective mass, which in itself arises from strong electron interaction. The energy gaps of fractional states and the temperature dependence of R(xx) at ν=1/2 point to large residual interactions between composite fermions.

Fermi surface and superconductivity in low-density high-mobility δ-doped SrTiO3

The electronic structure of low-density n-type SrTiO3 δ-doped heterostructures is investigated by angular dependent Shubnikov-de Haas oscillations. In addition to a controllable crossover from a three- to two-dimensional Fermi surface, clear beating patterns for decreasing dopant layer thicknesses are found. These indicate the lifting of the degeneracy of the conduction band due to subband quantization in the two-dimensional limit. Analysis of the temperature-dependent oscillations shows that similar effective masses are found for all components, associated with the splitting of the light electron pocket. The dimensionality crossover in the superconducting state is found to be distinct from the normal state, resulting in a rich phase diagram as a function of dopant layer thickness.

Common origin of the circular-dichroism pattern in angle-resolved photoemission spectroscopy of SrTiO3 and Cu(x)Bi2Se3

Circular dichroism in the angular distribution of photoelectrons from SrTiO(3):Nb and Cu(x)Bi(2)Se(3) is investigated by 7-eV laser angle-resolved photoemission spectroscopy. In addition to the well-known node that occurs in the circular dichroism pattern when the incidence plane matches the mirror plane of the crystal, we show that another type of node occurs when the mirror plane of the crystal is vertical to the incidence plane and the electronic state is two-dimensional. The flower-shaped circular dichroism patterns in the angular distribution occurring around the Fermi level of SrTiO(3):Nb and around the Dirac point of Cu(x)Bi(2)Se(3) are explained on equal footings. We point out that the penetration depth of the topological states of Cu(x)Bi(2)Se(3) depends on momentum.

Microsurgical skill assessment: toward skill-based surgical robotic control

A surgical skill assessment system was developed to quantify microsurgical skills. Infrared optical makers, an inertial measurement unit, and strain gauges were mounted on tweezers to record surgical tasks. In preliminary experiments, the tool tip trajectory, acceleration, and applied force were measured and microsurgery videos were evaluated by three expert surgeons. The preliminary results indicated the feasibility of the system by showing the significant difference between unskilled and skilled surgeons.

Histopathological manifestations of membranoproliferative glomerulonephritis and glomerular expression of plasmalemmal vesicle-associated protein-1 in a patient with polycythemia vera

Only a few cases of various glomerulonephropathies have been reported in patients with polycythemia vera. We report the case of a 72-year-old female with polycythemia vera in whom renal biopsy examination showed membranoproliferative glomerulonephritis (MPGN)-like lesion and glomerular expression of plasmalemmal vesicle-associated protein-1 (PV-1), a marker of glomerular capillary remodeling after injury. Prior to admission to our hospital for nephrotic syndrome, she had received hydroxyurea and phlebotomy. On admission, she was hypertensive with pretibial edema, hepatosplenomegaly, massive proteinuria (6.14 g/day), low serum albumin (2.9 g/dl), high fibrinogen, fibrin/fibrinogen degradation products and thrombomodulin levels, but with normal serum creatinine and complement levels. Microscopic examination of a renal biopsy demonstrated MPGN-like features with double contour and mesangial interposition. Electron microscopy showed subendothelial deposits, platelets attached to glomerular capillary walls and fibrin deposition. Immunofluorescence study identified IgM deposition along part of the capillary wall and mesangium. CD42b-positive platelets and megakaryocytes were detected in glomerular capillaries, accompanied with increased expression of platelet-derived growth factor receptor b and thrombomodulin in the mesangium and glomerular capillary, respectively. PV-1 was expressed along the glomerular capillary. Anti-platelet and anticoagulant combination therapy, together with the use of anti-hypertensive agents and hydroxyurea, resulted in improvement of the nephrotic syndrome. The findings suggested that activated platelets, enhanced coagulation state and endothelial damage may contribute to glomerulonephropathy associated with polycythemia vera.

Dominant mobility modulation by the electric field effect at the LaAlO3/SrTiO3 interface

Caviglia et al. [Nature (London) 456, 624 (2008)] have found that the superconducting LaAlO3/SrTiO3 interface can be gate modulated. A central issue is to determine the principal effect of the applied electric field. Using magnetotransport studies of a gated structure, we find that the mobility variation is almost 5 times that of the sheet carrier density. Furthermore, superconductivity can be suppressed at both positive and negative gate bias. These results indicate that the relative disorder strength strongly increases across the superconductor-insulator transition.

Green tea catechin inhibits lipopolysaccharide-induced bone resorption in vivo

BACKGROUND AND OBJECTIVE

Bone resorption is positively regulated by receptor activator of nuclear factor-kappaB ligand (RANKL). Pro-inflammatory cytokines, such as interleukin (IL)-1beta, promote RANKL expression by stromal cells and osteoblasts. Green tea catechin (GTC) has beneficial effects on human health and has been reported to inhibit osteoclast formation in an in vitro co-culture system. However, there has been no investigation of the effect of GTC on periodontal bone resorption in vivo. We therefore investigated whether GTC has an inhibitory effect on lipopolysaccharide (LPS)-induced bone resorption.

MATERIAL AND METHODS

Escherichia coli (E. coli) LPS or LPS with GTC was injected a total of 10 times, once every 48 h, into the gingivae of BALB/c mice. Another group of mice, housed with free access to water containing GTC throughout the experimental period, were also injected with LPS in a similar manner.

RESULTS

The alveolar bone resorption and IL-1beta expression induced by LPS in gingival tissue were significantly decreased by injection or oral administration of GTC. Furthermore, when GTC was added to the medium, decreased responses to LPS were observed in CD14-expressing Chinese hamster ovary (CHO) reporter cells, which express CD25 through LPS-induced nuclear factor-kappaB (NF-kappaB) activation. These findings demonstrated that GTC inhibits nuclear translocation of NF-kappaB activated by LPS. In addition, osteoclasts were generated from mouse bone marrow macrophages cultured in a medium containing RANKL and macrophage colony-stimulating factor with or without GTC. The number of osteoclasts was decreased in dose-dependent manner when GTC was added to the culture medium.

CONCLUSION

These results suggest that GTC suppresses LPS-induced bone resorption by inhibiting IL-1beta production or by directly inhibiting osteoclastogenesis.

Significance of collagenous and mucinous spherulosis in breast cytology specimens

OBJECTIVE

Spherulosis of the breast is a rare but distinct benign morphological entity. As there are few cytological reports of breast spherulosis, the significance of spherulosis among cytological specimens is unclear. The objective was to document cytological aspects of spherulosis.

METHODS

A total of 3491 consecutive breast fine needle aspiration cytology (FNAC) samples and 69 nipple discharge cytology samples were reviewed. Papanicolaou-stained slides with or without Romanowsky staining were analysed. The corresponding 1926 histological specimens were also reviewed.

RESULTS

We detected 17 cases of collagenous spherulosis (CS) and/or mucinous spherulosis (MS) among 3560 breast cytology specimens (0.48%). All samples were from women, who varied in age from 22 to 69 years. CS and/or MS were present in 15 of 3491 FNAC specimens (0.43%) and in two of 69 nipple discharge cytology specimens (2.9%). Corresponding histological specimens were available for 14 of the 17 specimens. Of the 14 specimens, 12 consisted of intraductal papilloma, one of fibroadenoma, and one of fibrocystic change. There was no spherulosis among the 1251 cytological specimens of malignant diseases.

CONCLUSIONS

Cytological evidence of spherulosis is a good indicator of intraductal papilloma.

Vanishing hall coefficient in the extreme quantum limit in photocarrier-doped SrTiO3

We explore the extreme quantum limit of photogenerated electrons in quantum paraelectric SrTiO3. This regime is distinct from conventional semiconductors, due to the large electron effective mass and large dielectric constant. At low temperature, the magnetoresistance and Hall resistivity saturate at a high magnetic field, deviating from conventional behavior. As a result, the Hall coefficient vanishes on the scale of the ratio of the Landau level splitting to the thermal energy, indicating the essential role of lowest Landau level occupancy, as limited by thermal broadening.

Apparent diffusion coefficient of pituitary macroadenoma evaluated with line-scan diffusion-weighted imaging

OBJECTIVE

The goal of this study was to evaluate the consistency of pituitary macroadenoma using apparent diffusion coefficient (ADC) with line-scan diffusion-weighted imaging (LSDWI).

METHODS

Patients with pituitary macroadenoma (n=19) were studied prospectively. The LSDWI was performed using a maximum b factor of 1000 s/mm2. The consistency of macroadenoma was rated as soft, intermediate or hard at transsphenoidal surgery. The ADC values of tumors were compared with the tumor-consistency ratings.

RESULTS

A soft consistency was found at surgery in 13 patients (mean ADC: 0.84+/-0.1x10(-3) mm2/s); an intermediate consistency was observed in six patients (mean ADC: 0.81+/-0.16x10(-3) mm2/s). No tumors of hard consistency were found. There was no significant difference in ADC values between tumors of soft consistency compared with tumors of intermediate consistency (P=0.37).

CONCLUSIONS

A relationship between tumor consistency and the ADCs of soft and intermediate macroadenomas was not shown in this study using LSDWI.

Is the adjustment of serum creatinine level < 0.6 mg/dl to 0.6 mg/dl justified in estimates of carboplatin clearance calculated by the Jelliffe formula?

5072

Background: The Jelliffe formula (JF) does not include body surface area (BSA) or body weight to adjust the body size. We demonstrated that estimates of carboplatin clearance calculated by the JF tend to have greater positive bias compared to other formulae. The JF has been used to estimate carboplatin clearance in Gynecologin Oncology Group studies. In patients with serum creatinine level <0.6 mg/dl, it is adjusted to 0.6 mg/dl in estimates of carboplatin clearance (Adjusted-Jelliffe formula (AJF)). The purpose of this study is to evaluate whether this adjustment is suitable. Methods: Carboplatin clearance was estimated in 115 patients with serum creatinine <0.6 mg/dl who received carboplatin-based chemotherapy for gynecologic malignancies between January 1996 and August 2004. Creatinine clearance was estimated using the Cockroft-Gault formula (CGF), JF, and AJF. The median percent error (MPE) and the median absolute percent error (MAPE) were evaluated by comparing carboplatin clearance. The relationships between BSA and ratios of estimated carboplatin clearance (JF/CGF, AJF/CGF) were evaluated by using simple regression. Results: The estimated carboplatin clearances were: CGF, 126.7 ± 27.7; JF, 148.2 ± 20.5; AJF, 130.5 ± 14.3. Comparing the results of the CGF with the JF, AJF yielded MPEs of +20%, +6%, and MAPEs of 21%, 14%, respectively. There were the linear correlations between ratio of estimated carboplatin clearances and BSA (Y1 = −1.141X + 2.830, Y2 = -1.061 X + 2.581, Y1: ratio of carboplatin clearance (JF/CGF), Y2: ratio of carboplatin clearance (AJF/CGF), X: BSA). Conclusions: As expected, carboplatin clearance was decreased by adjusting serum creatinine to 0.6 mg/ml, but it did not adjust the bias by BSA. Estimates of carboplatin clearance calculated by the AJF tend to have greater negative bias, particularly when the BSA of the patient is large.

No significant financial relationships to disclose.

B cells play an important role in lipopolysaccharide-induced bone resorption

The host immune system, especially activated T cells, plays a crucial role in inflammatory bone resorption and osteoclastogenesis. Previously, we showed that T cells are involved in inflammatory bone resorption in vivo. However, little is known about whether B cells are involved in inflammatory bone resorption and how B cells take part in osteoclastogenesis. Therefore, the aim of this study was to examine whether B c ells truly influence inflammatory bone resorption in vivo. Alveolar bone resorption in normal mice, in SCID mice that lack both B and T cells, and in B cell-reconstituted SCID mice was compared histopathologically after repeated injections of lipopolysaccharide (LPS) into the gingiva. Furthermore, we examined whether the B cells that are stimulated by LPS are involved in osteoclastogenesis in vitro. As a result, the B cell-reconstituted SCID mice showed stronger inflammatory bone resorption than the SCID mice. Also, in vitro, LPS-stimulated B cells enhanced osteoclastogenesis and anti-tumor necrosis factor (TNF)-alpha antibody completely blocked osteoclastogenesis induced by LPS-stimulated B cells. These results suggest that B cells promote inflammatory bone resorption through TNF-alpha.

[A case of pulmonary edema after electroconvulsive therapy under propofol anesthesia]

Electroconvulsive therapy (ECT) was scheduled for a 61-yr-old woman with major depression who had been taking a beta-blocker for hypertension. She underwent the first ECT under thiamylal anesthesia uneventfully. The second ECT was performed under propofol anesthesia on the next day. Immediately after ECT, the heart rate dropped from 56 to 19 beats.min-1, which was remedied by intravenous atropine. Then, the blood pressure increased to 204/108 mmHg but it was controlled by nicardipine. However, the SpO2 decreased to 84-88% under oxygen administration by mask at a rate of 3 l.min-1. The patient complained of chest discomfort and had a bloody secretion from the trachea. A chest X-ray showed a butterfly shadow. The patient was diagnosed as having neurogenic pulmonary edema and was treated in the ICU by artificial ventilation and administration of diuretics and catecholamines. These treatments proved to be successful, and the patient was discharged from the ICU 4 days later uneventfully. This case indicates that hemodynamics should be carefully monitored following ECT and that care should be taken to prevent the occurrence of complications after ECT.

Recovery of Infectious Human Parainfluenza Type 2 Virus from cDNA Clones and Properties of the Defective Virus without V-Specific Cysteine-Rich Domain

A full-length cDNA clone was constructed from the genome of the human parainfluenza type 2 virus (hPIV2). First, Vero cells were infected with recombinant vaccinia virus expressing T7 RNA polymerase, and then the plasmid encoding the antigenome sequence was transfected into Vero cells together with polymerase unit plasmids, NP, P, and L, which were under control of the T7 polymerase promoter. Subsequently, the transfected cells were cocultured with fresh Vero cells. Rescue of recombinant hPIV2 (rPIV2) from cDNA clone was demonstrated by finding the introduced genetic tag. As an application of reverse genetics, we introduced one nucleotide change (UCU to ACU) to immediate downstream of the RNA-editing site of the V gene in the full-length hPIV2 cDNA and were able to obtain infectious viruses [rPIV2V(-)] from the cDNA. The rPIV2V(-) possessed a defective V protein that did not have the unique cysteine-rich domain in its carboxyl terminus (the V-protein-specific domain). The rPIV2V(-) showed no growth in CV-1 and FL cells. Replication of the rPIV2V(-) in these cells, however, was partially recovered by adding anti-interferon (IFN)-beta antibody into the culture medium, showing that the rPIV2V(-) is highly sensitive against IFN and that no growth of rPIV2V(-) in CV-1 and FL cells is mainly due to its hypersensitivity to endogenously produced IFN. These findings indicate that the V-protein-specific domain of hPIV2 is related to IFN resistance. On the other hand, the rPIV2V(-) efficiently replicated in Vero cells, which are known as a IFN-non-producers. However, the virus yields of rPIV2V(-) in Vero cells were 10- to100-fold lower than those of control rPIV2, although syntheses of the viral-specific proteins and their mRNAs in rPIV2V(-)-infected Vero cells were augmented up to 48 p.i. in comparison with those of rPIV2. Furthermore, the rPIV2V(-) virions showed anomalous in size as compared with rPIV2 virions. These results suggest that the V protein plays an important role in the hPIV2 assembly, maturation, and morphogenesis.

Incomplete replication of human parainfluenza virus type 4 in LLC-MK2 cells and in L929 cells

Human parainfluenza virus type 4A (hPIV-4A) and type 4B (hPIV-4B) were tested for their ability to replicate in the monkey kidney LLC-MK2 cell line (MK2 cells) and the murine L929 cell line (L929 cells). These cells are normally non-permissive for replication of hPIV-4; however, treatment with acetylated trypsin led to virus replication in MK2 cells, but was less effective for L929 cells. Endogenously produced interferon (IFN) played no role in virus replication in L929 cells. Synthesis of virus-specific polypeptides was suppressed in L929 cells. Whereas NP-mRNA and HN-mRNA were detected in MK2 cells, no HN-mRNA was detected in L929 cells. These results indicate that hPIV-4 can infect both MK2 cells and L929 cells. In MK2 cells, when protease exists in the extracellular medium, hPIV-4 exhibits multistep growth. In L929 cells, however, the cause of incomplete replication might be lack of other unknown factors.

Osmium-metal coating device using hollow-cathode plasma CVD method

A novel osmium-metal coating device for SEM observation has been developed to prevent negative charge build-up on specimens by applying the hollow-cathode low voltage discharge plasma chemical vapour deposition (CVD) method. The CVD method using the hollow-cathode offers the following advantages. (i) The method can deposit osmium-metal at very low discharge voltage that is as low as half of that of the planar parallel electrode method. Therefore, the method avoids damage due to ion bombardment during the coating process. (ii) The method can minimize the quantity of the OsO4 gas by introducing directly into the hollow-cathode. This feature is important to prevent the air pollution caused by the purged gas. (iii) A large coating area is guaranteed because the Os ion is filled in the hollow-cathode where the specimen is holed. (iv) The lower discharge voltage can be used by mixing Ar, N2 or air with the OsO4 gas as the environmental gas in the chamber. (v) The hybrid coating is also available by lining the appropriate metal material such as platinum (Pt) on the surface of the inside of the hollow-cathode. The method uses the plasma CVD of Os metal as well as the ion-sputter deposition of the lined metal.

Isolation and characterization of monoclonal antibodies directed against murine FRP-1/CD98/4F2 heavy chain: murine FRP-1 is an alloantigen and amino acid change at 129 (P<-->R) is related to the alloantigenicity

Nineteen mAb directed against murine fusion regulatory protein-1 (mFRP-1)/4F2/CD98 were isolated and their biological properties were analysed. Intriguingly, mFRP-1 was found to be an alloantigen, namely, FRP-1.1 (DBA/2 and CBA mice type) and FRP-1.2 (BALB/c, C57BL/6 and C3H/He mice type). The nucleotide sequences of FRP-1.1 and FRP-1.2 were determined, demonstrating that amino acid change at 129 (P<-->R) is related to the alloantigenicity. mFRP-1 is expressed on thymocytes, on spleen cells, on peripheral lymphocytes and on blood monocytes, suggesting that the physiological role in vivo of murine FRP-1 is different from that of human FRP-1. The biological activities of antimFRP-1 mAbs showed by the present study are: (i) enhancement of Newcastle disease virus-induced cell fusion; (ii) suppression of HIVgp160-mediated cell fusion; and (iii) induction of aggregation and multinucleated giant cells of monocytes/macrophages.

[Reoperation for mitral regurgitation 13 years after aortic valve replacement and manouguian's anulus enlargement: report of a case]

The patient was 22-year-old female. She had undergone aortic valve replacement and Manouguian's anulus enlargement with low porosity woven Dacron patch for congenital aortic stenosis 13 years ago, and developed mitral regurgitation 9 years after that operation. Two regurgitant flow were observed. One was originated from the orifice due to mitral prolapse. The other was from a tear in the anterior leaflet. It was around the tip of the prosthetic patch, approximately 7 mm in size, and was repaired easily. But the mitral valve itself was found to be malformed and prolapsed, requiring mitral valve replacement. Her postoperative course was uneventful.

[Successful surgical treatment for type B aortic dissection with Marfan's syndrome after aortic root and mitral valve replacement: report of a case]

A 30-year-old female with Marfan's syndrome underwent aortic root replacement for annuloaortic ectasia and mitral valve replacement for mitral regurgitation. She remained well until 16 months postoperatively when she had sudden onset of pain. Preoperative angiogram showed Stanford B aortic dissection. Thoracoabdominal aortic replacement was performed successfully under deep hypothermic bypass.

Effect of ibudilast on ciliary activity of human paranasal sinus mucosa in vitro

The effect of ibudilast (CAS 50847-11-5, 3-isobutyryl-2-isopropylpyrazolo[1,5-a]pyridine, KC-404), an anti-asthmatic drug, on ciliary beat frequency (CBF) of human paranasal sinus mucosa was examined in vitro. Ciliary activation was observed after a 10-min exposure to 4.6 x 10(-6) mol/l ibudilast. Ibudilast dose-dependently increase CBF at the concentrations ranging from 4.6 x 10(-7) mol/l to 4.6 x 10(-5) mol/l. Propranolol inhibited ciliary activity induced by ibudilast; however, neither indometacin nor verapamil affected the activation of ibudilast on CBF. Platelet activating factor (PAF) and Leukotriene D4 (LTD4) are chemical mediators inducing mucosal dysfunction and damage. Ibudilast prevented ciliary inhibition induced by PAF and LTD4. These findings indicated that ibudilast activates CBF and inhibits the effect of PAF and LTD4 on ciliated cells, and consequently improves the pathogenesis of allergic disorders such as the inhibited mucociliary transport system and airway hyperresponsiveness.

[Pollen of gramineae and its botanical, taxonomical, and ecological aspects]

This is a review of tropical pollens (Gramineae) which cause allergy, addressed to medical workers and with emphasis in the Costa Rican. The graminean family Poaceae is widely distributed and has great genetic plasticity. An evolutionary tendency to floral reduction has led to anemophily, with pollens ranging from large (e.g. corn, Zea mays) to very small (e.g. tribes Poae and Avenae). This family produces a large number of pollens per panicle. The early morning production of free pollen (before 8 am) enhances allergic problems. In contrast, in rice (Oryza sativa) most pollen is liberated near mid day, which favours long range dispersal because of more appropriate environmental temperature and humidity. This can explain why rice is the first cause of allergic sensitivization in the asthmatic patients of the Costa Rican driest provinces (Guanacaste and Puntarenas). Despite the small size of several temperate and tropical species are present, because of geographic position, climatic diversity, irregular topography, etc. This paper presents a general description of the subfamilies Pooideae, Panicoideae, Chlorideae (Eragrostoideae) and Oryzoideae (including the medically most important tribes). Their pollens are illustrated with light and electron microscopy.