154 research outputs found
Electrical transport properties of small diameter single-walled carbon nanotubes aligned on ST-cut quartz substrates
A method is introduced to isolate and measure the electrical transport
properties of individual single-walled carbon nanotubes (SWNTs) aligned on an
ST-cut quartz, from room temperature down to 2 K. The diameter and chirality of
the measured SWNTs are accurately defined from Raman spectroscopy and atomic
force microscopy (AFM). A significant up-shift in the G-band of the resonance
Raman spectra of the SWNTs is observed, which increases with increasing SWNTs
diameter, and indicates a strong interaction with the quartz substrate. A
semiconducting SWNT, with diameter 0.84 nm, shows Tomonaga-Luttinger liquid and
Coulomb blockade behaviors at low temperatures. Another semiconducting SWNT,
with a thinner diameter of 0.68 nm, exhibits a transition from the
semiconducting state to an insulating state at low temperatures. These results
elucidate some of the electrical properties of SWNTs in this unique
configuration and help pave the way towards prospective device applications
An efficient decentralized learning by exploiting biarticular muscles - A case study with a 2D serpentine robot -
2008 IEEE International Conference on Robotics and Automation, Pasadena, CA, USA, May 19-23, 200
Positioning and Microvibration Control by Electromagnets of an Air Spring Vibration Isolation System
Active positioning and microvibration control has been attempted by electromagnets equipped in a bellows-type, air-spring vibration isolation system. Performance tests have been carried out to study the effects. The main components of the system's isolation table were four electromagnetic actuators and controllers. The vibration isolation table was also equipped with six acceleration sensors for detecting microvibration of the table. The electromagnetic actuators were equipped with bellows-type air springs for passive support of the weight of the item placed on the table, with electromagnets for active positioning, as well as for microvibration control, and relative displacement sensors. The controller constituted a relative feedback system for positioning control and an absolute feedback system for vibration isolation control. In the performance test, a 1,490 kg load (net weight of 1,820 kg) was placed on the vibration isolation table, and both the positioning and microvibration control were carried out electromagnetically. Test results revealed that the vibration transmission was reduced by 95%
Technique for single-step lymphocyte isolation from an endoscopic biopsy specimen for the diagnosis of gastrointestinal lymphoma
In this paper, we introduce a simplified, one-step procedure for lymphocyte isolation from an endoscopically biopsied fragment. For lymphocyte isolation, an endoscopically harvested specimen and 5 mL of normal saline solution were placed in a wire mesh strainer set in a porcelain bowl. To obtain the lymphocyte suspension, the solid specimen was crushed using the rubber portion of a plunger of a 10 mL injection syringe. Flow cytometry was performed using the lymphocyte suspension. For validating our methods, the one-step lymphocyte isolation technique was used to perform flow cytometry on samples from 23 patients with (n = 12) or without (n = 11) gastrointestinal lymphoma. Flow cytometry of light chain expression was performed in all patient samples (feasibility: 100%). Sensitivity was 83.3% (10/12) and specificity was 100% (11/11). In conclusion, lymphocytes isolated from a single endoscopic biopsy specimen using our simplified and quick procedure are suitable for flow cytometry. Considering that flow cytometry has an important advantage of providing the results on the examination day itself, the results of this study suggest that flow cytometric analysis using our single-step lymphocyte isolation technique can be potentially used to diagnose lymphoma in the gastrointestinal mucosa
The Origin of the Charge Ordering and Its Relevance to Superconductivity in -(BEDT-TTF)X: The Effect of the Fermi Surface Nesting and the Distant Electron-Electron Interactions
The origin of the charge ordering in organic compounds -(BEDT-TTF) ((SCN), Tl,Rb,Co, Cs,Zn) is studied using an extended
Hubbard model. Calculating the charge susceptibility within random phase
approximation (RPA), we find that the charge
ordering observed at relatively high temperatures can be considered as a
consequence of a cooperation between the Fermi surface nesting, controlled by
the hopping integral in the direction, and the electron-electron
interactions, where the distant (next nearest neighbor) interactions that have
not been taken into account in most of the previous studies play an important
role.Mean field analysis at T=0 also supports the RPA results, and further
shows that in the charge ordered state, some portions of the Fermi
surface remain ungapped and are nested with a nesting vector close to the
modulation wave vector of the horizontal stripe ordering observed at low
temperatures in (SCN). We further study the possibility of
superconductivity by taking into account the distant off-site repulsions and
the band structure corresponding to I, in which superconductivity is
experimentally observed. We find that there is a close competition between
-wave-like singlet pairing and -wave-like triplet pairing due
to a cooperation between the charge and the spin fluctuations. The present
analysis provides a possible unified understanding of the experimental phase
diagram of the -(BEDT-TTF) family, ranging from a charge ordered
insulator to a superconductor.Comment: 13 pages, 18 figures (Figs.5,6,7,14,15,18 compressed using jpeg2ps
Light-dependent induction of Edn2 expression and attenuation of retinal pathology by endothelin receptor antagonists in Prominin-1- deficient mice
Retinitis pigmentosa (RP) and macular dystrophy (MD) are prevalent retinal degenerative diseases associated with gradual photoreceptor death. These diseases are often caused by genetic mutations that result in degeneration of the retina postnatally after it has fully developed. The Prominin-1 gene (Prom1) is a causative gene for RP and MD, and Prom1- knockout (KO) mice recapitulate key features of these diseases including light-dependent retinal degeneration and stenosis of retinal blood vessels. The mechanisms underlying progression of such degeneration have remained unknown, however. We here analysed early events associated with retinal degeneration in Prom1-KO mice. We found that photoreceptor cell death and glial cell activation occur between 2 and 3 weeks after birth. High-throughput analysis revealed that expression of the endothelin-2 gene (Edn2) was markedly up-regulated in the Prom1-deficient retina during this period. Expression of Edn2 was also induced by light stimulation in Prom1-KO mice that had been reared in the dark. Finally, treatment with endothelin receptor antagonists attenuated photoreceptor cell death, gliosis, and retinal vessel stenosis in Prom1-KO mice. Our findings suggest that inhibitors of endothelin signalling may delay the progression of RP and MD and therefore warrant further study as potential therapeutic agents for these diseases
Enhancement of superconducting properties in FeSe wires using a quenching technique
Enhancements of superconducting properties were observed in FeSe wires using
a quenching technique. Zero resistivity was achieved at about 10 K in quenched
wires, which is about 2 K higher than that of polycrystalline FeSe bulk.
Furthermore, transport Jc of quenched wires showed three times higher than that
of furnace-cooled wires. In contrast, the quenched polycrystalline FeSe bulks
did not show the enhancement of Tc. The quenching technique is a greatly
promising for fabricating FeSe wires with high Tc and high Jc, and quenched
FeSe wires have high potential for superconducting wire applications
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