Nonreciprocal Phonon Propagation in a Metallic Chiral Magnet.

The phonon magnetochiral effect (MChE) is the nonreciprocal acoustic and thermal transports of phonons caused by the simultaneous breaking of the mirror and time-reversal symmetries. So far, the phonon MChE has been observed only in a ferrimagnetic insulator Cu_{2}OSeO_{3}, where the nonreciprocal response disappears above the Curie temperature of 58 K. Here, we study the nonreciprocal acoustic properties of a room-temperature ferromagnet Co_{9}Zn_{9}Mn_{2} for unveiling the phonon MChE close to room temperature. Surprisingly, the nonreciprocity in this metallic compound is enhanced at higher temperatures and observed up to 250 K. This clear contrast between insulating Cu_{2}OSeO_{3} and metallic Co_{9}Zn_{9}Mn_{2} suggests that metallic magnets have a mechanism to enhance the nonreciprocity at higher temperatures. From the ultrasound and microwave-spectroscopy experiments, we conclude that the magnitude of the phonon MChE of Co_{9}Zn_{9}Mn_{2} mostly depends on the Gilbert damping, which increases at low temperatures and hinders the magnon-phonon hybridization. Our results suggest that the phonon nonreciprocity could be further enhanced by engineering the magnon band of materials.

Direct visualization of the three-dimensional shape of skyrmion strings in a noncentrosymmetric magnet.

Magnetic skyrmions are topologically stable swirling spin textures that appear as particle-like objects in two-dimensional (2D) systems. Here, utilizing scalar magnetic X-ray tomography under applied magnetic fields, we report the direct visualization of the three-dimensional (3D) shape of individual skyrmion strings in the room-temperature skyrmion-hosting non-centrosymmetric compound Mn1.4Pt0.9Pd0.1Sn. Through the tomographic reconstruction of the 3D distribution of the [001] magnetization component on the basis of transmission images taken at various angles, we identify a skyrmion string running through the entire thickness of the sample, as well as various defect structures, such as the interrupted and Y-shaped strings. The observed point defect may represent the Bloch point serving as an emergent magnetic monopole, as proposed theoretically. Our tomographic approach with a tunable magnetic field paves the way for direct visualization of the structural dynamics of individual skyrmion strings in 3D space, which will contribute to a better understanding of the creation, annihilation and transfer of these topological objects.

Particle-size dependent structural transformation of skyrmion lattice.

Magnetic skyrmion is a topologically protected particle-like object in magnetic materials, appearing as a nanometric swirling spin texture. The size and shape of skyrmion particles can be flexibly controlled by external stimuli, which suggests unique features of their crystallization and lattice transformation process. Here, we investigated the detailed mechanism of structural transition of skyrmion lattice (SkL) in a prototype chiral cubic magnet Cu2OSeO3, by combining resonant soft X-ray scattering (RSXS) experiment and micromagnetic simulation. This compound is found to undergo a triangular-to-square lattice transformation of metastable skyrmions by sweeping magnetic field (B). Our simulation suggests that the symmetry change of metastable SkL is mainly triggered by the B-induced modification of skyrmion core diameter and associated energy cost at the skyrmion-skyrmion interface region. Such internal deformation of skyrmion particle has further been confirmed by probing the higher harmonics in the RSXS pattern. These results demonstrate that the size/shape degree of freedom of skyrmion particle is an important factor to determine their stable lattice form, revealing the exotic manner of phase transition process for topological soliton ensembles in the non-equilibrium condition.

Propagation dynamics of spin excitations along skyrmion strings.

Magnetic skyrmions, topological solitons characterized by a two-dimensional swirling spin texture, have recently attracted attention as stable particle-like objects. In a three-dimensional system, a skyrmion can extend in the third dimension forming a robust and flexible string structure, whose unique topology and symmetry are anticipated to host nontrivial functional responses. Here we experimentally demonstrate the coherent propagation of spin excitations along skyrmion strings for the chiral-lattice magnet Cu2OSeO3. We find that this propagation is directionally non-reciprocal and the degree of non-reciprocity, as well as group velocity and decay length, are strongly dependent on the character of the excitation modes. These spin excitations can propagate over a distance exceeding 50 µm, demonstrating the excellent long-range ordered nature of the skyrmion-string structure. Our combined experimental and theoretical analyses offer a comprehensive account of the propagation dynamics of skyrmion-string excitations and suggest the possibility of unidirectional information transfer along such topologically protected strings.

Multiple-q noncollinear magnetism in an itinerant hexagonal magnet.

Multiple-q spin order, i.e., a spin texture characterized by a multiple number of coexisting magnetic modulation vectors q, has recently attracted attention as a source of nontrivial magnetic topology and associated emergent phenomena. One typical example is the triple-q skyrmion lattice state stabilized by Dzyaloshinskii-Moriya interactions in noncentrosymmetric magnets, while the emergence of various multiple-q states of different origins is expected according to the latest theories. Here, we investigated the magnetic structure of the itinerant polar hexagonal magnet Y3Co8Sn4, in which several distinctive mechanisms favoring multiple-q states are allowed to become active. Small-angle neutron-scattering experiments suggest the formation of incommensurate triple-q magnetic order with an in-plane vortex-like spin texture, which can be most consistently explained in terms of the novel four-spin interaction mechanism inherent to itinerant magnets. The present results suggest a new route to realizing exotic multiple-q orders and that itinerant hexagonal magnets, including the R 3 M 8Sn4 family with wide chemical tunability, can be a unique material platform to explore their rich phase diagrams.

Low-Field Bi-Skyrmion Formation in a Noncentrosymmetric Chimney Ladder Ferromagnet.

The real-space spin texture and the relevant magnetic parameters were investigated for an easy-axis noncentrosymmetric ferromagnet Cr_{11}Ge_{19} with Nowotny chimney ladder structure. Using Lorentz transmission electron microscopy, we report the formation of bi-Skyrmions, i.e., pairs of spin vortices with opposite magnetic helicities. The quantitative evaluation of the magnetocrystalline anisotropy and Dzyaloshinskii-Moriya interaction (DMI) proves that the magnetic dipolar interaction plays a more important role than the DMI on the observed bi-Skyrmion formation. Notably, the critical magnetic field value required for the formation of bi-Skyrmions turned out to be extremely small in this system, which is ascribed to strong easy-axis anisotropy associated with the characteristic helix crystal structure. The family of Nowotny chimney ladder compounds may offer a unique material platform where two distinctive Skyrmion formation mechanisms favoring different topological spin textures can become simultaneously active.

Electrochemical microdevices for rapid and on-site determination of the minimum inhibitory concentration of antibiotics.

A tool for rapid selection of appropriate antibiotics may be useful to maximize the benefits of their effectiveness against severe infectious diseases. In this study, we propose a microdevice that works with surface tension-driven sample introduction and impedance measurements for on-site, rapid estimation of suitable antibiotics.

Cephalometric evaluation after two-stage palatoplasty combined with a Hotz plate: a comparative study between the modified Furlow and Widmaier-Perko methods.

The effects on craniofacial growth of two different soft palate repair techniques in two-stage palatoplasty were investigated. This was a retrospective, cross-sectional cohort study of 68 children with non-syndromic, complete unilateral cleft lip and palate. Thirty-four patients were treated with the modified Furlow method (F-group) and the remaining 34 with the Widmaier-Perko method (P-group). Craniofacial growth was assessed by analyzing 12 angular and 12 linear measurements on lateral cephalograms. Composite facial diagrams from the two groups were compared with those of a control non-cleft group. Angular and linear measurements did not differ significantly between the two groups, implying that the craniofacial morphology was not affected by the difference in soft palate repair technique. However, small differences in anterior nasal spine and posterior nasal spine were found in cleft patients compared with controls. These findings suggest that the modified Furlow and Widmaier-Perko methods have a similar impact on craniofacial growth. Considering speech function, the modified Furlow method provides better craniofacial growth and speech function. However, the long-term effects of both methods on craniofacial growth after growth cessation remain to be determined.

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.

A small compound targeting TACC3 revealed its different spatiotemporal contributions for spindle assembly in cancer cells.

The mitotic spindle is assembled by the coordinated action of centrosomes and kinetochore microtubules. An evolutionally conserved protein family, transforming acidic coiled-coil (TACC), has been shown to be involved in this process. In humans, TACC3 is aberrantly expressed in a variety of human cancers, but its biological significance remains to be elucidated. Here, using a novel compound targeting TACC3, spindlactone (SPL), we show that the perturbation of TACC3 selectively inhibited the nucleation of centrosome microtubules in ovarian cancer cells. In contrast to centrosome microtubules, the kinetochore microtubules were robustly assembled, forming ectopic spindle poles that resulted in multipolar spindles. Interestingly, the extensive inhibition of TACC3 partially suppressed the nucleation of kinetochore microtubules. These dose-dependent effects of SPL were consistent with the results observed by the depletion of TACC3 and its binding partner, colonic and hepatic tumor overexpressed gene protein (TOGp). Although these proteins both have roles in the assembly of centrosome and kinetochore microtubules, their contributions were spatiotemporally different. Notably, SPL did not affect spindle assembly in normal cells. Furthermore, the oral administration of SPL significantly suppressed tumor growth in vivo. The unique mechanism of action of SPL not only enables it to be used as a tool to dissect the molecular basis of spindle assembly but also to provide a rationale for the use of TACC3 as a molecular target for cancer treatment. This rationale offers an opportunity to develop new strategies for cancer chemotherapy that overcome the limitations of microtubule toxins and expand their scope and clinical efficacy.

Zoledronic acid impairs re-epithelialization through down-regulation of integrin αvß6 and transforming growth factor beta signalling in a three-dimensional in vitro wound healing model.

This study examined the negative effects of zoledronic acid on the re-epithelialization of oral mucosa in a three-dimensional in vitro oral mucosa wound healing model. A living oral mucosa equivalent was constructed by seeding a mixture of primary human oral keratinocytes and fibroblasts, at a cell density of 1.5 × 10(5)cm(2) each, onto human cadaver dermis. This was cultured in a submerged condition in 1.2mM Ca(2+) EpiLife for 5 days, and then in an air-liquid interface for 14 days. The equivalent was wounded by excising a linear 2-mm-wide epithelial layer on day 8 and subsequently incubated with 10 µM zoledronic acid for an additional 11 days. Histological and immunohistochemical observations revealed zoledronic acid to significantly suppress the epithelial thickness and Ki-67-labelling index. Zoledronic acid also abolished integrin αvß6 expression, implying impaired keratinocyte migration. Zoledronic acid did not attenuate the total transforming growth factor beta 1 (TGF-ß1) production into the supernatant, but down-regulated TGF-ß receptor types I and II expression and Smad3 phosphorylation, as was also confirmed by immunofluorescence microscopy. This study therefore showed zoledronic acid to abrogate integrin αvß6 expression, cause the down-regulation of TGF-ß/Smad signalling in oral keratinocytes, and impair re-epithelialization, suggesting compromised oral mucosa homeostasis in patients receiving zoledronic acid.

Inflammatory histopathogenesis of nasopalatine duct cyst: a clinicopathological study of 41 cases.

OBJECTIVE: The aim of this study is to characterize immunohistochemical profiles of lining epithelia of nasopalatine duct cyst (NPC) as well as to correlate those findings with their clinicopathological features to understand the histopathogenesis of NPC. MATERIALS AND METHODS: Forty-one surgical specimens from NPC were examined for clinical profiles and expression of keratin-7, 13, MUC-1, and P63 by immunohistochemistry, compared to radicular cyst (RC) and maxillary sinusitis. RESULTS: Nasopalatine duct cyst was clinically characterized by male predominant occurrence: 44% of the cases involved tooth roots, and 70% with inflammatory backgrounds. Lining epithelia of NPCs without daughter cysts were immunohistochemically distinguished into three layers: a keratin 7-positive (+) ciliated cell layer in the surface, a keratin-13+ middle layer, and a MUC-1+/P63+ lower half, indicating that they were not respiratory epithelia, and the same layering pattern was observed in RC. However, those immunolocalization patterns of the main cyst lining with daughter cyst were exactly the same as those of daughter cyst linings as well as duct epithelia of mucous glands. CONCLUSIONS: Two possible histopathogenesis of NPC were clarified: one was inflammatory cyst like RC and the other was salivary duct cyst-like mucocele.

A case of desmoplastic ameloblastoma arising in the maxillary alveolus: the origin and time-course changes in the early stage of tumour development observed on dental radiographs.

In this article we report a case of desmoplastic ameloblastoma in which chronological changes in the early development can be observed on dental radiographs. The tumour grew very slowly and did not appear to have a strong potential for local extension like typical ameloblastomas. Radiological findings of our case suggest the tumour arose from the periodontal membrane. However, it was not possible to obtain conclusive histopathological evidence.

Complication of adenoid cystic carcinoma and sialolithiasis in the submandibular gland: report of a case and its etiological background.

The authors report a case of adenoid cystic carcinoma (ACC) complicated with sialolithiasis of the submandibular gland. The patient was a 43-year-old female with a history of papillotubular carcinoma of the breast almost at the same time. She had noticed a swelling in her sublingual area for 10 years, which was later diagnosed by her dentist to be due to a sialolith in the left submandibular gland. After several years of observation, the patient was referred to have her left submandibular gland, containing the stone, surgically removed with a diagnosis of atrophic sialadenitis. Histopathologically, the submandibular gland was extensively replaced with fibrous granulation tissue, in which there were small but invasive foci of ACC. The present case indicates that ACC could arise in the background of chronic sialadenitis. It is suggested that long-standing sialadenitis cases should be carefully examined to exclude suspicion of malignancy before surgery.

Clinical study on prognostic factors for autotransplantation of teeth with complete root formation.

Autotransplantation is often performed to replace a missing tooth, but tooth autotransplantation has been reported in fewer teeth with complete root formation than those with incomplete root formation. The aim of this prospective study was to evaluate the factors that affect the prognosis of autotransplantation of teeth with complete root formation. 109 patients with 117 transplants were studied. Of the 117 transplants investigated, 14 (12%) failed during the observation period. The overall 1-year survival rate was 96%; the 5-year survival rate was 84%. The major causes of failure were unsuccessful initial healing and replacement root resorption with periodontal inflammation. Factors significantly associated with unsuccessful transplantation, in single factor analysis, were age 40 years or more, molar tooth as donor, probing pocket depth to 4mm or more, history of root canal treatment, multi-rooted teeth and fixation with sutures. Pocket depth of 4mm or more and history of root canal treatment appeared to increase the risk of unsuccessful transplantation in multivariate analysis. It is suggested that the pocket depth of the donor tooth and history of root canal treatment are related to the healing of paratransplantal tissue and root resorption.

Thumb polydactyly with symphalangism in young children.

Six cases of young children with thumb polydactyly in which the radial component was complicated by symphalangism are reported. Since the symphalangism was cartilaginous, plain X-rays showed an apparent joint space. However, its continuity was confirmed at surgery. Thumb polydactyly with symphalangism may be more common than previously expected.

Assessment of 14 functional gene polymorphisms in Japanese patients with oral lichen planus: a pilot case-control study.

Oral lichen planus (OLP) is a refractory mucosal disease. Its pathogenesis is thought to involve immunologic and genetic alterations. To gain a better understanding of the genetic risk factors, the authors evaluated associations between 14 functional gene polymorphisms and OLP. 32 Japanese patients with OLP and 99 unrelated healthy Japanese controls were genotyped for 14 single nucleotide polymorphisms (SNPs) of genes that regulate host immune responses. Genotyping was performed with a modified version of the serial invasive signal amplification reaction. A trend towards over-representation of tumor necrosis factor receptor 2 (TNFR2) +587 G allele was found in the patients compared with the controls (allele frequency: P=0.049). The other 13 SNPs were unassociated with OLP. These results suggest that TNFR2 +587 gene polymorphism may be associated with susceptibility to OLP.

Cementum-periodontal ligament complex regeneration using the cell sheet technique.

BACKGROUND AND OBJECTIVE: In the present study we evaluated if a multilayered human periodontal ligament cell sheet could reconstruct the physiological architecture of a periodontal ligament-cementum complex. MATERIAL AND METHODS: Human periodontal ligament cells were isolated and then cultured in dishes coated with a temperature-responsive polymer to allow cell detachment as a cell sheet. In the control group, human periodontal ligament cells were cultured in Dulbecco's modified Eagle's minimal essential medium containing 10% fetal bovine serum and 1% antibiotics. In the experimental group, human periodontal ligament cells were cultured in Dulbecco's modified Eagle's minimal essential medium and osteodifferentiation medium containing dexamethasone, ascorbic acid and beta-glycerophosphate. After 3 wk, scanning electron microscopy was carried out, in addition to staining for alkaline phosphatase activity and for calcium (using the Von Kossa stain). Then human periodontal ligament cell sheets were multilayered and placed onto dentin blocks. The constructs were transplanted subcutaneously into the back of immunodeficient rats. At 1 and 6 wk after transplantation, the animals were killed. Demineralized tissue sections were stained using hematoxylin and eosin, and Azan, and then analyzed. RESULTS: After 3 wk of culture in osteodifferentiation medium, human periodontal ligament cells produced mineral-like nodules and also showed positive staining for alkaline phosphatase, calcium (Von Kossa) and mRNA expression of type I collagen. By contrast, in the control group only weak alkaline phosphatase staining was observed, the Von Kossa stain was negative and there was no mRNA expression of type I collagen. Six weeks after transplantation with human periodontal ligament cells cultured in osteodifferentiation medium, most of the dentin surfaces showed a newly immature cementum-like tissue formation and periodontal ligament with perpendicular orientation inserted into the newly deposited cementum-like tissue. CONCLUSION: This study suggests that the multilayered temperature-responsive culture system can be used as a novel strategy for periodontal regeneration. The human periodontal ligament cell sheet technique may be applicable for regeneration of the clinical periodontal ligament-cementum complex.

Treatment of oesophageal ulcerations using endoscopic transplantation of tissue-engineered autologous oral mucosal epithelial cell sheets in a canine model.

BACKGROUND: With the recent development of endoscopic submucosal dissection (ESD), large oesophageal cancers can be removed with a single procedure, with few limits on the resectable range. However, after aggressive ESD, a major complication that arises is postoperative inflammation and stenosis that can considerably affect the patient's quality of life. AIMS: To examine a novel treatment combining ESD and the endoscopic transplantation of tissue-engineered cell sheets created using autologous oral mucosal epithelial cells, in a clinically relevant large animal model. METHODS: Oral mucosal epithelial cells, harvested from beagle dogs, were cultured under normal conditions at 37 degrees C, on temperature-responsive dishes. After ESD (5 cm in length, 180 degrees in range), cell sheets were harvested by a simple reduction in temperature to 20 degrees C, and transplanted by endoscopy. RESULTS: The transplanted cell sheets were able to adhere to and survive on the underlying muscle layers in the ulcer sites, providing an intact, stratified epithelium. Four weeks after surgery, complete wound healing, with no observable stenosis, was seen in the animals receiving autologous cell sheet transplantation. By contrast, noticeable fibrin mesh and host inflammation, consistent with the intermediate stages of wound healing, were observed in the control animals that received only ESD. CONCLUSIONS: These findings in a clinically relevant canine model show the effectiveness of a novel combined endoscopic approach for the potential treatment of oesophageal cancers that can effectively enhance wound healing and possibly prevent postoperative oesophageal stenosis.