Correlation between morphology and transport properties of quasi-free-standing monolayer graphene

We investigate the morphology of quasi-free-standing monolayer graphene (QFMLG) formed at several temperatures by hydrogen intercalation and discuss its relationship with transport properties. Features corresponding to incomplete hydrogen intercalation at the graphene-substrate interface are observed by scanning tunneling microscopy on QFMLG formed at 600 and 800{\deg}C. They contribute to carrier scattering as charged impurities. Voids in the SiC substrate and wrinkling of graphene appear at 1000{\deg}C, and they decrease the carrier mobility significantly

Graphene-Based Nano-Electro-Mechanical Switch with High On/Off Ratio

Locally defined nanomembrane structures can be produced in graphene films on a SiC substrate with atomic steps. The contact conductance between graphene and a metal-coated nanoprobe in scanning probe microscopy can be drastically reduced by inducing local buckling of the membranes. Repeatable current switching with high reproducibility can be realized. The on/off ratio can be varied from about 105 to below 10 by changing the contact force. At a low contact force, the contact conductance changes from 10μS (‘‘ON’’ state) to 100pS (‘‘OFF’’ state). This novel device structure could represent a new path to electrical switching at the nanoscale

Efficient Assay for Total Antioxidant Capacity in Human Plasma Using a 96-Well Microplate

In the present study, we tried to establish an efficient assay for total antioxidant capacity (TAC) in human plasma using a 96-well microplate. TAC was assessed using lag time by antioxidants against the myoglobin-induced oxidation of 2,2'-azino-di(3-ethylbenzthiazoline-6-sulfonic acid (ABTS) with hydrogen peroxide, and expressed as Trolox equivalent. The linearity of the calibration curve with Trolox was maintained with the Trolox concentration range from 2.5 µM to 25 µM (R2 = 0.997). The assay was applied to the measurement of TAC in healthy human plasma. Coefficient of variation in intraday assay was 2.4%. Difference was not observed in interday assay. Plasma TAC of men ((569 ± 41) µM Trolox equivalent; n = 6) was higher than that of women ((430 ± 28) µM Trolox equivalent; n = 4). After the vegetable juice was drunk for 1 week, the increase in plasma TAC was observed in almost all the volunteers. In summary, we developed the efficient assay for plasma TAC using a 96-well microplate

Effects of UV light intensity on electrochemical wet etching of SiC for the fabrication of suspended graphene

We report on the effects of UV light intensity on the photo assisted electrochemical wet etching of SiC(0001) underneath an epitaxially grown graphene for the fabrication of suspended structures. The maximum etching rate of SiC(0001) was 2.5µm/h under UV light irradiation in 1wt% KOH at a constant current of 0.5mA/cm2. The successful formation of suspended structures depended on the etching rate of SiC. In the Raman spectra of the suspended structures, we did not observe a significant increase in the intensity of the D peak, which originates from defects in graphene sheets. This is most likely explained by the high quality of the single-crystalline graphene epitaxially grown on SiC

コンクリートの劣化および劣化の事例 : 塩害･中性化･硫酸塩劣化の事例

素晴らしきコンクリート

Transcutaneous Electrical Nerve Stimulation on the PC-5 and PC-6 Points Alleviated Hypotension after Epidural Anaesthesia, Depending on the Stimulus Frequency

Neuraxial blockade causes arterial hypotension. Transcutaneous electrical nerve stimulation (TENS) at the Neiguan (PC-6) and Jianshi (PC-5) reduces the severity of hypotension after spinal anaesthesia, but did not clarify the optimal stimulus frequency. We hypothesized that the stimulus frequency of TENS at the PC-6 and PC-5 points would influence the severity of hypotension after epidural anaesthesia. 65 ASA I or II male patients presenting for inguinal hernia repair were randomized to five groups: the control group received no treatment; the 2 Hz, 10 Hz, 20 Hz, and 40 Hz groups received TENS at a frequency of 2 Hz, 10 Hz, 20 Hz, and 40 Hz, respectively. The lowest SBP was significantly higher in the 40 Hz group [the control, 84 (74–110) mmHg; the 2 Hz, 96 (62–116) mmHg; the 10 Hz, 100 (68–110) mmHg; the 20 Hz, 96 (64–115) mmHg; the 40 Hz, 104 (75–140) mmHg: P = 0.004]. Significantly less patients experienced hypotension in the 40 Hz group [the control, 78%; the 2 Hz, 43%; the 10 Hz, 38%; the 20 Hz, 38%; the 40 Hz, 8%: P = 0.008]. TENS on the PC-6 and PC-5 points reduced the severity and incidence of hypotension after epidural anaesthesia, depending on the stimulus frequency

Microscopic Raman Mapping of Epitaxial Graphene on 4H-SiC(0001)

We propose a quality control method for wafer-scale epitaxial graphene grown on SiC substrates. The peak position of Raman spectra of epitaxial graphene is an excellent indicator of film quality and reveals irregularities, such as graphene thickness inhomogeneity and SiC substrate defects. A comparison of microscopic Raman maps and scanning probe microscopy images of the same position of the sample revealed that wave numbers of Raman peaks (G and 2D band peaks) were strongly correlated with the strain in the graphene film. The increase in number of graphene layers (2 to 3–4 layers) induced phonon softening (~6 cm-1) and broadening (~6 cm-1) of the 2D band peak. Significant phonon softening and abnormal broadening of the Raman peaks were observed at residual scratches on the SiC substrate. The quantitative layer number distribution of graphene on SiC is successfully estimated from the wave number distribution of the 2D band peak