Single-layered assembly of vanadium pentoxide nanowires on graphene for nanowire-based lithography technique.

Graphene nanoribbon (GNR)-based materials are a promising device material because of their potential high carrier mobility and atomically thin structure. Various approaches have been reported for preparing the GNR-based materials, from bottom-up chemical synthetic procedures to top-down fabrication techniques using lithography of graphene. However, it is still difficult to prepare a large-scale GNR-based material. Here, we develop a procedure to prepare a large-scale GNR network using networked single-layer inorganic nanowires. Vanadium pentoxide (V2O5) nanowires were assembled on graphene with an interfacial layer of a cationic polymer via electrostatic interaction. A large-scale nanowire network can be prepared on graphene and is stable enough for applying an oxygen plasma. Using plasma etching, a networked graphene structure can be generated. Removing the nanowires results in a networked flat structure whose both surface morphology and Raman spectrum indicate a GNR networked structure. The field-effect device indicates the semiconducting character of the GNR networked structure. This work would be useful for fabricating a large-scale GNR-based material as a platform for GNR junctions for physics and electronic circuits.

Electronic Structure Mosaicity of Monolayer Transition Metal Dichalcogenides by Spontaneous Pattern Formation of Donor Molecules.

Modulating the electronic structure of semiconducting materials is critical to developing high-performance electronic and optical devices. Transition metal dichalcogenides (TMDCs) are atomically thin semiconducting materials. However, before they can be used successfully in electronic and optical devices, modulation of their carrier concentration at the nanometer scale must be achieved. Molecular doping has been successful in modulating the carrier concentration; however, the scientific approach for selective and local carrier doping at the nanometer scale is still missing. Here, we demonstrate a proof-of-concept of modulating the carrier concentration of TMDCs laterally on a scale of around 100 nm using spontaneous pattern formation of an ultrathin film consisting of molecular electron dopants. When the water made contact with the molecular film (∼10 nm), a spontaneous pattern formation was observed on both the monolayer and bulk TMDCs. We revealed that the pattern-formation dynamics and nanoscopic flow rate of the molecules were highly dependent on the thickness of the TMDCs, since the band gap varies based on the number of layers. Analyses of topographic images of the molecular patterns and photoluminescence spectra of the TMDCs indicated that the spontaneously patterned molecular films induced a local carrier doping. Our results demonstrate a spontaneous formation of a mosaic electronic structure. This work is useful for making tiny-scale electronic junctions on TMDCs and semiconducting materials to make numerous p/n junctions simultaneously for optoelectronic devices.

Convection-Flow-Assisted Preparation of a Strong Electron Dopant, Benzyl Viologen, for Surface-Charge Transfer Doping of Molybdenum Disulfide.

Transition metal dichalcogenides (TMDCs) have received attention as atomically thin post-silicon semiconducting materials. Tuning the carrier concentrations of the TMDCs is important, but their thin structure requires a non-destructive modulation method. Recently, a surface-charge transfer doping method was developed based on contacting molecules on TMDCs, and the method succeeded in achieving a large modulation of the electronic structures. The successful dopant is a neutral benzyl viologen (BV0); however, the problem remains of how to effectively prepare the BV0 molecules. A reduction process with NaBH4 in water has been proposed as a preparation method, but the NaBH4 simultaneously reacts vigorously with the water. Here, a simple method is developed, in which the reaction vial is placed on a hotplate and a fragment of air-stable metal is used instead of NaBH4 to prepare the BV0 dopant molecules. The prepared BV0 molecules show a strong doping ability in terms of achieving a degenerate situation of a TMDC, MoS2. A key finding in this preparation method is that a convection flow in the vial effectively transports the produced BV0 to a collection solvent. This method is simple and safe and facilitates the tuning of the optoelectronic properties of nanomaterials by the easily-handled dopant molecules.

Heparin inhibits osteoclastic differentiation and function.

We investigated the effects of Glycosaminoglycans (GAGs) on mouse monocytic cell line in regard to their differentiation, proliferation, and function in vitro. RAW 264.7 cells were cultured with receptor activator of NF-kappaB ligand (RANKL) and various GAGs. Osteoclastic cells were visualized by staining for tartrate-resistant acid phosphatase (TRAP) and detected using a phenyl-phosphate substrate method. RAW 264.7 cells were also cultured with stimulants contained in BD BioCoat OSTEOLOGIC(TM) kit, and bone resorption activity was assessed by counting the numbers of resorption pits. We also examined the effect of heparin on cell growth using MTT assay, while the expression level of c-Src protein was determined by immunoblot analysis. Heparin suppressed TRAP-positive multinucleated cell formation and TRAP activity induced by RANKL, whereas the other GAGs showed no effects on osteoclast differentiation. Heparin also inhibited the formation of resorption pits, while the others did not. In the MTT assay, none of the tested GAGs had an influence on RAW 264.7 cell proliferation. However, heparin reduced the level of c-Src protein in RAW 264.7 cells stimulated with RANKL. To determine the affinity of heparin and RANKL, they were subjected by HiTrap heparin column chromatography and each fraction was collected. Western blotting analysis revealed the expression of RANKL in the fraction bound to heparin. The binding of RANKL and heparin was confirmed by quartz-crystal microbalance. These results indicate that the inhibitory effect of heparin toward osteoclastogenesis induced by RANKL is due to the binding of heparin to RANKL.

Tuning Transition-Metal Dichalcogenide Field-Effect Transistors by Spontaneous Pattern Formation of an Ultrathin Molecular Dopant Film.

Spontaneous pattern formation is an energetically favorable process and is shown in nature in molecular-scale assembly, biological association, and soft material organizations. The opposite regime, the artificial process, which is widely applied to the fabrication of semiconducting devices, such as lithographic techniques, requires enormous amounts of energy. Here, we propose a concept of tuning the properties of semiconducting MoS2 and WSe2 devices using the spontaneous pattern formation of adjacent molecular films. The film used was a 10 nm thick ultrathin film of a molecular electron dopant, which exhibited spontaneous pattern formation and dynamically transformed the morphology of tiny holes, a network, a maze, and dots on substrates, including SiO2, MoS2, and WSe2. These patterns were exhibited only when the film came in contact with water and was tuned with temperature and time. The specific lengths of the patterns were less than 200 nm, which is sufficiently smaller than the exfoliated ∼10 µm semiconducting MoS2 and WSe2 flakes. The properties of the field-effect devices of MoS2 and WSe2 were found to be modified according to the pattern formation process of the ultrathin molecular film on the device. This concept applies the spontaneous patterning phenomena shown in nature to the fabrication and optimization of electronic devices by using molecular films and their responses to the external environment.

Advanced clinical usefulness of ultrasonography for diseases in oral and maxillofacial regions.

Various kinds of diseases may be found in the oral and maxillofacial regions and various modalities may be applied for their diagnosis, including intra-oral radiography, panoramic radiography, ultrasonography, computed tomography, magnetic resonance imaging, and nuclear medicine methods such as positron emission tomography. Of these modalities, ultrasound imaging is easy to use for the detection of noninvasive and soft tissue-related diseases. Doppler ultrasound images taken in the B-mode can provide vascular information associated with the morphology of soft tissues. Thus, ultrasound imaging plays an important role in confirming the diagnosis of many kinds of diseases in such oral and maxillofacial regions as the tongue, lymph nodes, salivary glands, and masticatory muscles. In the present article, we introduce three new applications of ultrasonography: guided fine-needle aspiration, measurement of tongue cancer thickness, and diagnosis of metastasis to cervical lymph nodes.

Clinical significance of ultrasonographic examination including detection of thyroid gland diseases when surveying cervical lymph nodes in subjects with oral squamous cell carcinoma.

OBJECTIVE: The objective of this study was to evaluate the clinical significance of ultrasonography (US) for screening for thyroid gland diseases when surveying the cervical lymph nodes to detect metastasis in subjects with oral squamous cell carcinoma (SCC). METHODS: The detection rates and characteristics of abnormal thyroid findings detected by US in 301 subjects with oral SCC were analyzed. Subjects with abnormal findings were referred to thyroid specialists and the diagnoses and treatments from these specialists were noted. The ratio of subjects who consulted a thyroid specialist after indications of thyroid gland abnormalities to analyze subject compliance was also examined. Follow-up examinations were regularly conducted to assess any changes in the thyroid gland. RESULTS: Of the 301 subjects with oral SCC, 91 had abnormal thyroid gland findings on US. As subject age increased, the rate of detection of abnormal thyroid gland findings on US significantly increased. The rate of detection of abnormal findings in women by US was significantly higher than that in men, but the male-to-female ratio was lower compared with that in previous reports. It was demonstrated that oral SCC in the floor of the mouth was associated with the highest prevalence of abnormal findings in the thyroid gland (40%), followed by oral SCC of the maxillary gingiva (39%). Of the 91 subjects with abnormal findings, 10 showed enlargement in the size of the lesion on follow-up examination with US. Eleven subjects with no abnormal findings on initial examination showed abnormal findings on follow-up examination. CONCLUSION: The results suggest that subjects with oral SCC have a relatively high rate of abnormal findings in the thyroid gland that can be detected by US. Scans that include the thyroid gland should be performed when surveying cervical lymph nodes for metastasis during US examination. Particular attention should be paid to thyroid gland-related diseases in older men who have oral cancer and to thyroid gland abnormalities if patients had oral SCC in the floor of the mouth or of the maxillary gingiva. It is recommended that follow-up US examinations be regularly performed in cases of oral SCC.

Compressive mechanical stress promotes osteoclast formation through RANKL expression on synovial cells.

OBJECTIVES: We investigated the effects of compressive mechanical stress on osteoclastogenesis of synovial cells to clarify the mechanism of osteoclast formation by those cells in temporomandibular joint (TMJ) disorders. STUDY DESIGN: Synovial cells were isolated from rat knee joints and continuously compressed using a conventional method. The expression of receptor activator nuclear factor kappaB ligand (RANKL) mRNA and protein in synovial cells was analyzed by reverse transcriptase-polymerase chain reaction, immunoblotting, and immunofluorescence staining. Mouse bone marrow cells were cultured with synovial cells for 7 days to detect osteoclasts. RESULTS: The expressions of RANKL mRNA and protein in synovial cells were increased with compressive force. When mouse bone marrow cells were cultured with continuously compressed synovial cells, tartrate-resistant acid phosphatase-positive multinucleated cells were formed. Osteoprotegerin completely inhibited osteoclast formation induced by culturing with compressed synovial cells. CONCLUSION: Our results indicated that the expression of RANKL in compressed synovial cells enhanced osteoclast formation, whereas continuous compressive force may induce osteoclastic bone destruction in the TMJ.

Dermatan sulfate inhibits osteoclast formation by binding to receptor activator of NF-kappa B ligand.

Dermatan sulfate (DS) is a major component of extracellular matrices in mammalian tissues. In the present study, DS demonstrated a high level of binding activity to receptor activator of NF-kappaB ligand (RANKL) and obstructed the binding of RANK to RANKL, determined using a quartz-crystal microbalance (QCM) technique. Further, when mouse bone marrow cells were cultured with RANKL and macrophage colony-stimulating factor, DS suppressed tartrate-resistant acid phosphatase-positive multinucleated cell formation in a dose-dependent manner. In addition, immunoblot analyses revealed that DS reduced the levels of phosphorylation of p38 mitogen-activated protein kinase and extracellular signal-regulated kinase protein in mouse osteoclast progenitor cells stimulated with RANKL. Together, these results indicate that DS regulates osteoclast formation through binding to RANKL and inhibition of signal transduction in osteoclast progenitor cells, suggesting that it has an important role in bone metabolism in pathological conditions.

Mechanisms involved in enhancement of osteoclast formation and function by low molecular weight hyaluronic acid.

Hyaluronic acid (HA) is a component of the extracellular matrix that has been shown to play an important role in bone formation, resorption, and mineralization both in vivo and in vitro. We examined the effects of HA at several molecular weights on osteoclast formation and function induced by RANKL (receptor activator of NF-kappa B ligand) in a mouse monocyte cell line (RAW 264.7). HA at M(r) < 8,000 (low molecular weight HA (LMW-HA)) enhanced tartrate-resistant acid phosphatase-positive multinucleated cell formation and tartrate-resistant acid phosphatase activity induced by RANKL in a dose-dependent manner, whereas HA at M(r) > 900,000 (high molecular weight HA (HMW-HA)) showed no effect on osteoclast differentiation. LMW-HA enhanced pit formation induced by RAW 264.7 cells, whereas HMW-HA did not, and LMW-HA stimulated the expression of RANK (receptor activator of NF-kappa B) protein in RAW 264.7 cells. In addition, we found that LMW-HA enhanced the levels of c-Src protein and phosphorylation of ERKs and p38 MAPK in RAW 264.7 cells stimulated with RANKL, whereas the p38 MAPK inhibitor SB203580 inhibited RANKL-induced osteoclast differentiation. This enhancement of c-Src and RANK proteins induced by LMW-HA was inhibited by CD44 function-blocking monoclonal antibody. These results indicate that LMW-HA plays an important role in osteoclast differentiation and function through the interaction of RANKL and RANK.