Imaging of isotope diffusion using atomic-scale vibrational spectroscopy.

The spatial resolutions of even the most sensitive isotope analysis techniques based on light or ion probes are limited to a few hundred nanometres. Although vibrational spectroscopy using electron probes has achieved higher spatial resolution1-3, the detection of isotopes at the atomic level4 has been challenging so far. Here we show the unambiguous isotopic imaging of 12C carbon atoms embedded in 13C graphene and the monitoring of their self-diffusion via atomic-level vibrational spectroscopy. We first grow a domain of 12C carbon atoms in a pre-existing crack of 13C graphene, which is then annealed at 600 degrees Celsius for several hours. Using scanning transmission electron microscopy-electron energy loss spectroscopy, we obtain an isotope map that confirms the segregation of 12C atoms that diffused rapidly. The map also indicates that the graphene layer becomes isotopically homogeneous over 100-nanometre regions after 2 hours. Our results demonstrate the high mobility of carbon atoms during growth and annealing via self-diffusion. This imaging technique can provide a fundamental methodology for nanoisotope engineering and monitoring, which will aid in the creation of isotope labels and tracing at the nanoscale.

Electrical properties of bilayer graphene synthesized using surface wave microwave plasma techniques at low temperature.

Bilayer graphene was synthesized at low temperature using surface wave microwave plasma techniques where poly(methyl metacrylate) (PMMA) and methane (CH4) were used as carbon sources. Temperature-dependent Hall effect measurements were carried out in a helium atmosphere. Sheet resistance, sheet carrier density and mobility showed weak temperature dependence for graphene from PMMA, and the highest carrier mobility is 740 cm2 V-1 s-1. For graphene from CH4, tunneling of the domain boundary limited carrier transport. The difference in average domain size was determined by Raman signal maps. In addition, residuals of PMMA were detected on graphene from PMMA. The low sheet resistances of graphene synthesized at a temperature of 280 °C using plasma techniques were explained by the PMMA related residuals rather than the domain sizes.

Development of an amorphous selenium-based photodetector driven by a diamond cold cathode.

Amorphous-selenium (a-Se) based photodetectors are promising candidates for imaging devices, due to their high spatial resolution and response speed, as well as extremely high sensitivity enhanced by an internal carrier multiplication. In addition, a-Se is reported to show sensitivity against wide variety of wavelengths, including visible, UV and X-ray, where a-Se based flat-panel X-ray detector was proposed. In order to develop an ultra high-sensitivity photodetector with a wide detectable wavelength range, a photodetector was fabricated using a-Se photoconductor and a nitrogen-doped diamond cold cathode. In the study, a prototype photodetector has been developed, and its response to visible and ultraviolet light are characterized.

Patterning of graphene using wet etching with hypochlorite and UV light.

Graphene patterning via etching is important for enhancing or controling the properties of devices and supporting their applications in micro- and nano-electronic fields. Herein, we present a simple, low-cost, and scalable wet etching method for graphene patterning. The technique uses hypochlorite solution combined with ultraviolet light irradiation to rapidly remove unwanted graphene areas from the substrate. Raman spectroscopy, atomic force microscopy, scanning electron microscopy, and optical microscopy results showed that well-patterned graphene with micrometer scale regions was successfully prepared. Furthermore, graphene field effect transistor arrays were fabricated, and the obtained devices exhibited good current-voltage characteristics, with maximum mobility of ~ 1600 cm2/Vs, confirming the feasibility of the developed technique.

Large-Scale 1T'-Phase Tungsten Disulfide Atomic Layers Grown by Gas-Source Chemical Vapor Deposition.

The control of crystal polymorphism and exploration of metastable, two-dimensional, 1T'-phase, transition-metal dichalcogenides (TMDs) have received considerable research attention. 1T'-phase TMDs are expected to offer various opportunities for the study of basic condensed matter physics and for its use in important applications, such as devices with topological states for quantum computing, low-resistance contact for semiconducting TMDs, energy storage devices, and as hydrogen evolution catalysts. However, due to the high energy difference and phase change barrier between 1T' and the more stable 2H-phase, there are few methods that can be used to obtain monolayer 1T'-phase TMDs. Here, we report on the chemical vapor deposition (CVD) growth of 1T'-phase WS2 atomic layers from gaseous precursors, i.e., H2S and WF6, with alkali metal assistance. The gaseous nature of the precursors, reducing properties of H2S, and presence of Na+, which acts as a countercation, provided an optimal environment for the growth of 1T'-phase WS2, resulting in the formation of high-quality submillimeter-sized crystals. The crystal structure was characterized by atomic-resolution scanning transmission electron microscopy, and the zigzag chain structure of W atoms, which is characteristic of the 1T' structure, was clearly observed. Furthermore, the grown 1T'-phase WS2 showed superconductivity with the transition temperature in the 2.8-3.4 K range and large upper critical field anisotropy. Thus, alkali metal assisted gas-source CVD growth is useful for realizing large-scale, high-quality, phase-engineered TMD atomic layers via a bottom-up synthesis.

Low-reflective wire-grid polarizers with absorptive interference overlayers.

Wire-grid (WG) polarizers with low reflectivity for visible light have been successfully developed. We theoretically consider the optical properties of simple sandwich structures of absorptive layer/transparent layer (gap layer)/high-reflective mirrors and found that it is possible to develop an antireflection (AR) coating owing to the interference along with the absorption in the absorptive layer. A wide variety of materials can be used for AR coatings by tuning the thicknesses of both the absorptive and the gap layers. This AR concept has been applied to reduce the reflectance of WG polarizers of Al. FeSi(2) as an absorptive layer has been deposited by the glancing angle deposition technique immediately on the top of Al wires covered with a thin SiO(2) layer as a gap layer. For the optimum combination of the thicknesses of FeSi(2) and SiO(2), the reflectance becomes lower than a few per cent, independent of the polarization, whereas the transmission polarization properties remain good. Because low-reflective (LR) WG polarizers are completely composed of inorganic materials, they are useful for applications requiring high-temperature durability such as liquid crystal projection displays.

Gas Barrier Properties of Chemical Vapor-Deposited Graphene to Oxygen Imparted with Sub-electronvolt Kinetic Energy.

Graphene gas-barrier performance holds great interest from both scientific and technological perspectives. Using in situ synchrotron X-ray photoelectron spectroscopy, we demonstrate that chemical vapor-deposited monolayer graphene loses its gas-barrier performance almost completely when oxygen molecules are imparted with sub-electronvolt kinetic energy but retains its gas-barrier performance when the molecules are not energized. The permeation process is nondestructive. Molecular dynamics-based simulation suggests kinetic energy-mediated chemical reactions catalyzed by common graphene defects as a responsible mechanism.

[A case of dihydropyrimidine dehydrogenase (DPD) deficiency with severe side effects from UFT/Uzel administration].

5-FU is among the drugs most frequently used in the treatment of gastrointestinal malignancies. Also, it has been reported to reveal severe side effects in the case of a dihydropyrimidine dehydrogenase (DPD) deficiency. A 75-year-old man showed severe nausea and vomiting after administration of UFT/Uzel as adjuvant chemotherapy. Because of severe thrombocytopenia and grade 4 neutropenia, platelet transfusion and G-CSF administration were performed. With time, the leukocyte, neutrophil and platelet count recovered to normal level. We strongly suspected a DPD deficiency from the result of urinary pyrimidine analysis.

[A case of advanced breast cancer leading to DIC after chemotherapy].

We reported a case of DIC who was administered FEC90 (5-FU 1,000 mg/body, epirubicin 170 mg/body, cyclophosphamide 1,000 mg/body) for advanced breast cancer. A 55-year-old woman was referred to our hospital with lumbago. There was a huge tumor in her left breast (10x10 cm) and bone scintigraphy showed multiple bone metastasis, so she was treated with FEC90. Before the third course, DIC occurred. The patient was then treated with FOY and heparin, and the DIC was resolved. We think the DIC of this case was related with tumor lysis syndrome. Febrile neutropenia has been occasionally emphasized during chemotherapy, but due care must be taken for lymphocyte depletion during treatment.

Hippocampal transection for treatment of left temporal lobe epilepsy with preservation of verbal memory.

Despite good seizure outcome with temporal lobectomy, postoperative impairment of verbal memory remains unsolved. To address this problem we developed a new method, applying the rationale of multiple subpial transection (MST) to the hippocampus. The inferior ventricle is accessed without disrupting the neuronal pathways related to verbal memory. Intraoperative electrocorticography is recorded over the hippocampus and amygdala. After the extent of the epileptic area is determined, multiple transections of the pyramidal layer under the alveus is performed using specially designed ring transectors. After this procedure, epileptic discharges from the hippocampus can be completely abolished. Of 21 cases undergoing this operation, 12 left-sided and nine right-sided, 17 were followed up for more than one year. Fourteen (82%) are seizure free, two (12%) have rare seizures, and one (6%) has significantly improved. Of eight patients who underwent a battery of neuropsychometric tests both before and after left hippocampal transection, postoperative verbal memory was completely preserved in seven cases, and one transiently worsened patient recovered within 6 months. However, these results are still preliminary as the number of patients is small and the follow-up time short. The accumulation of cases and follow-up of greater duration will be necessary to precisely confirm the efficacy of this new technique.

ICAM-1 expression and the soluble ICAM-1 level for evaluating the metastatic potential of gastric cancer.

ICAM-1 plays an important role in cell-cell and cell-extracellular matrix interactions, especially tumor invasion and cytotoxicity of lymphocytes. In the present study, the relationship between metastasis of gastric cancer and ICAM-1 expression by cancer cells or the serum level of s-ICAM-1 was (s-ICAM-1) was examined. ICAM-1 was detected by immunohistochemic staining in 49.0% of 108 patients with gastric cancer. The ICAM-1 expression rate was higher at a more advanced stage, based on lymph node metastasis, being 46.9% in node-negative and 56.1% in node-positive cases. In patients with liver metastasis, the rate was 90.9%, while it was 43.3% in patients without liver metastasis (p < 0.05). The serum s-ICAM-1 level was 262.1 ng/ml (median 205.5, range 176.0-271.0) in healthy subjects and 391.5 ng/ml (median 317.5, range 148.7-1,768.0) in gastric cancer patients (p < 0.001). The serum s-ICAM-1 level was significantly higher in patients with liver metastasis than in patients without liver metastasis (p < 0.0001). In addition, positive ICAM-1 expression cases had significantly higher s-ICAM-1 levels than negative ones, 408.9 +/- 188.4 and 308.1 +/- 88.1 ng/ml, respectively. These results suggested that ICAM-1 was overexpressed in cancer cells and released as s-ICAM-1, which would promote hematogenous metastasis by suppressing local anticancer immunity.

Effects of RS-601, a novel leukotriene D(4)/thromboxane A(2) dual receptor antagonist, on asthmatic responses in guinea pigs.

The effects of 4-[4-[5,5,6,6,6-pentafluoro-1-(4-fluorobenzene-sulfonamido)hexyl]phenyl]butyric acid (RS-601), a novel leukotriene D(4) (LTD(4))/thromboxane A(2) (TxA(2)) dual receptor antagonist, on bronchial asthmatic responses in guinea pigs were examined. The effects were compared with those of pranlukast (LTD(4) receptor antagonist) and S-1452 (TxA(2) receptor antagonist). RS-601 inhibited the increase in airway resistance caused by LTD(4) and TxA(2) mimetic compound, U-46619, but not by histamine. RS-601 and pranlukast but not S-1452 inhibited an antigen-induced late asthmatic response. In addition, RS-601 inhibited an antigen-induced airway hyperresponsiveness (AHR), whereas pranlukast and S-1452 had no effect on the AHR. The antigen-induced increase in inflammatory cells in airway was not affected by all examined agents. Furthermore, bacterial lipopolysaccharide-induced AHR in guinea pigs was clearly suppressed by RS-601 but not by pranlukast and S-1452. The increase in airway inflammatory cells caused by lipopolysaccharide was not affected by all three drugs. These findings indicate that RS-601 has a potent antiasthmatic efficacy, especially on AHR, but does not affect accumulation of eosinophils in the airways.