215 research outputs found
Edge state on hydrogen-terminated graphite edges investigated by scanning tunneling microscopy
The edge states that emerge at hydrogen-terminated zigzag edges embedded in
dominant armchair edges of graphite are carefully investigated by
ultrahigh-vacuum scanning tunneling microscopy (STM) measurements. The edge
states at the zigzag edges have different spatial distributions dependent on
the - or -site edge carbon atoms. In the case that the defects
consist of a short zigzag (or a short Klein) edge, the edge state is present
also near the defects. The amplitude of the edge state distributing around the
defects in an armchair edge often has a prominent hump in a direction
determined by detailed local atomic structure of the edge. The tight binding
calculation based on the atomic arrangements observed by STM reproduces the
observed spatial distributions of the local density of states.Comment: 9 pages, 11 figures, accepted for Physical Review
Observation of zigzag and armchair edges of graphite using scanning tunneling microscopy and spectroscopy
The presence of structure-dependent edge states of graphite is revealed by
both ambient- and ultra-highvacuum- (UHV) scanning tunneling microscopy (STM) /
scanning tunneling spectroscopy (STS) observations. On a hydrogenated zigzag
(armchair) edge, bright spots are (are not) observed together with (SQRT(3) by
SQRT(3))R30 superlattice near the Fermi level (V_S = −30 mV for a peak of
the local density of states (LDOS)) under UHV, demonstrating that a zigzag edge
is responsible for the edge states, although there is no appreciable difference
between as-prepared zigzag and armchair edges in air. Even in hydrogenated
armchair edge, however, bright spots are observed at defect points, at which
partial zigzag edges are created in the armchair edge.Comment: 4 pages, 4 figures, contents for experimental/theoretical reseachers,
accepted as an issue of Physical Review B (PRB
Mechanism of magnetism in stacked nanographite with open shell electrons
Antiferromagnetism in stacked nanographite is investigated with using the
Hubbard-type models. The A-B stacking or the stacking near to that of A-B type
is favorable for the hexagonal nanographite with zigzag edges, in order that
magnetism appears. Next, we find that the open shell electronic structure can
be an origin of the decreasing magnetic moment with the decrease of the
inter-graphene distance, as experiments on adsorption of molecules suggest.Comment: 13 pages; Harigaya's Web site:
http://staff.aist.go.jp/k.harigaya/welcome_E.html; Nanotech. Inst. of AIST:
http://unit.aist.go.jp/nanotech
STM observation of the quantum interference effect in finite-sized graphite
Superperiodic patterns were observed by STM on two kinds of finite-sized
graphene sheets. One is nanographene sheets inclined from a highly oriented
pyrolitic graphite (HOPG) substrate and the other is several-layer-thick
graphene sheets with dislocation-network structures against a HOPG substrate.
As for the former, the in-plane periodicity increased gradually in the
direction of inclination, and it is easily changed by attachment of a
nanographite flake on the nanographene sheets. The oscillation pattern can be
explained by the interference of electron waves confined in the inclined
nanographene sheets. As for the latter, patterns and their corrugation
amplitudes depended on the bias voltage and on the terrace height from the HOPG
substrate. The interference effect by the perturbed and unperturbed waves in
the overlayer is responsible for the patterns whose local density of states
varies in space.Comment: 11 pages; 2 figures; accepted for publication in J. Phys. Chem.
Solids; ISIC1
Immunological and Psychological Benefits of Aromatherapy Massage
This preliminary investigation compares peripheral blood cell counts including red blood cells (RBCs), white blood cells (WBCs), neutrophils, peripheral blood lymphocytes (PBLs), CD4(+), CD8(+) and CD16(+) lymphocytes, CD4(+)/CD8(+) ratio, hematocrit, humoral parameters including serum interferon-γ and interleukin-6, salivary secretory immunoglobulin A (IgA). Psychological measures including the State–Trait Anxiety Inventory (STAI) questionnaire and the Self-rating Depression Scale (SDS) between recipients (n = 11) of carrier oil massage and aromatherapy massage, which includes sweet almond oil, lavender oil, cypress oil and sweet marjoram oil. Though both STAI and SDS showed a significant reduction (P < 0.01) after treatment with aromatherapy and carrier massage, no difference between the aromatherapy and control massage was observed for STAI and SDS. Aromatherapy, in contrast to control massage, did not significantly reduce RBC count or hematocrit. However, aromatherapy massage showed a significant (P > 0.05) increase in PBLs, possibly due to an increase in CD8(+) and CD16(+) lymphocytes, which had significantly increased post-treatment (P < 0.01). Consequently, the CD4(+)/CD8(+) ratio decreased significantly (P < 0.01). The paucity of such differences after carrier oil massage suggests that aromatherapy massage could be beneficial in disease states that require augmentation of CD8(+) lymphocytes. While this study identifies the immunological benefits of aromatherapy massage, there is a need to validate the findings prospectively in a larger cohort of patients
Renal shear wave velocity by acoustic radiation force impulse did not reflect advanced renal impairment
[Aim] Acoustic radiation force impulse is a noninvasive method for evaluating tissue elasticity on ultrasound. Renal shear wave velocity measured by this technique has not been fully investigated in patients with renal disease. The aim of the present study was to compare renal shear wave velocity in end‐stage renal disease patients and that in patients without chronic kidney disease and to investigate influencing factors. [Methods] Renal shear wave velocities were measured in 59 healthy young subjects (control group), 31 subjects without chronic kidney disease (non‐CKD group), and 39 end‐stage renal disease patients (ESRD group). Each measurement was performed 10 times at both kidneys, and the mean value of eight of 10 measurements, excluding the maximum and minimum values, was compared. [Results] Renal shear wave velocity could be measured in all subjects. Renal shear wave velocity in the control group was higher than in the non‐CKD group and in the ESRD group, and no difference was found between the non‐CKD group and the ESRD group. Age and depth were negatively correlated to the renal shear wave velocity. In multiple regression analysis, age and depth were independent factors for renal shear wave velocity, while renal impairment was not. There was no difference between the non‐CKD group and the ESRD group, even when ages were matched and depth was adjusted. [Conclusion] Renal shear wave velocity was not associated with advanced renal impairment. However, it reflected alteration of renal aging, and this technique may be useful to detect renal impairment in the earlier stages
STM observation of electronic wave interference effect in finite-sized graphite with dislocation-network structures
Superperiodic patterns near a step edge were observed by STM on
several-layer-thick graphite sheets on a highly oriented pyrolitic graphite
substrate, where a dislocation network is generated at the interface between
the graphite overlayer and the substrate. Triangular- and rhombic-shaped
periodic patterns whose periodicities are around 100 nm were observed on the
upper terrace near the step edge. In contrast, only outlines of the patterns
similar to those on the upper terrace were observed on the lower terrace. On
the upper terrace, their geometrical patterns gradually disappeared and became
similar to those on the lower terrace without any changes of their periodicity
in increasing a bias voltage. By assuming a periodic scattering potential at
the interface due to dislocations, the varying corrugation amplitudes of the
patterns can be understood as changes in LDOS as a result of the beat of
perturbed and unperturbed waves, i.e. the interference in an overlayer. The
observed changes in the image depending on an overlayer height and a bias
voltage can be explained by the electronic wave interference in the ultra-thin
overlayer distorted under the influence of dislocation-network structures.Comment: 8 pages; 6 figures; Paper which a part of cond-mat/0311068 is
disscussed in detai
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