1,154 research outputs found
Quantum Conductance Probing of Oxygen Vacancies in SrTiO3 Epitaxial Thin Film Using Graphene
The quantum Hall conductance in monolayer graphene on an epitaxial SrTiO3
(STO) thin film is studied to understand the role of oxygen vacancies in
determining the dielectric properties of STO. As the gate voltage sweep range
is gradually increased in our device, we observe systematic generation and
annihilation of oxygen vacancies evidenced from the hysteretic conductance
behavior in graphene. Furthermore, based on the experimentally observed linear
scaling relation between the effective capacitance and the voltage sweep range,
a simple model is constructed to manifest the relationship among the dielectric
properties of STO with oxygen vacancies. The inherent quantum Hall conductance
in graphene can be considered as a sensitive, robust, and non-invasive probe
for understanding the electronic and ionic phenomena in complex transition
metal oxides without impairing the oxide layer underneath.Comment: 21 pages, 4 figures, 2 supp. figure
FEASIBILITY OF BREWING MAKGEOLLI (TURBID RICE WINE) USING PARTIALLY GELATINIZED WHEAT FLOUR AND TAPIOCA FLOUR
Makgeolli is made from cooked rice or wheat, then brewed with nuruk (Korean fermentation starter) for several days. But, nowadays, attempts have been made to use various raw materials and process innovations to make makgeolli for particular purposes. This study aimed to evaluate the quality of makgeolly made from partially gelatinized wheat flour and tapioca flour. Five different combination of wheat flour and tapioca flour were used to manufacture makgeolli. The results showed that different combination of partially gelatinized wheat flour and tapioca flour significantly affected the chemical and sensorial characteristics of makgeolli. Increasing proportion of wheat flour produced higher level of total acid, amino acidity, reducing sugar and total solid of makgeolli. Inversely, alcohol content was higher when higher level of tapioca flour was used. In general, sensorial characteristics of makgeolli made from partially gelatinized wheat flour and tapioca flour didn’t acceptable by panelists. Thus, brewing makgeolli by using partially gelatinized wheat flour and tapioca flour isn’t acceptable in term of sensorial characteristics
Fast frequency discrimination and phoneme recognition using a biomimetic membrane coupled to a neural network
In the human ear, the basilar membrane plays a central role in sound
recognition. When excited by sound, this membrane responds with a
frequency-dependent displacement pattern that is detected and identified by the
auditory hair cells combined with the human neural system. Inspired by this
structure, we designed and fabricated an artificial membrane that produces a
spatial displacement pattern in response to an audible signal, which we used to
train a convolutional neural network (CNN). When trained with single frequency
tones, this system can unambiguously distinguish tones closely spaced in
frequency. When instead trained to recognize spoken vowels, this system
outperforms existing methods for phoneme recognition, including the discrete
Fourier transform (DFT), zoom FFT and chirp z-transform, especially when tested
in short time windows. This sound recognition scheme therefore promises
significant benefits in fast and accurate sound identification compared to
existing methods.Comment: 7 pages, 4 figure
Comparison of the Clinical Results of Attic Cholesteatoma Treatment: Endoscopic Versus Microscopic Ear Surgery
Objectives We aimed to compare clinical outcomes including hearing improvement and cholesteatoma recurrence between endoscopic and conventional microscopic surgeries in patients with attic cholesteatoma. Methods We collected data from patients with attic cholesteatoma who were treated using endoscopic (10 patients) and microscopic (10 patients) approaches by a single surgeon. The data were retrospectively reviewed for patient characteristics, intraoperative findings, hearing levels, and follow-up clinical status. Recurrence of the cholesteatoma, improvement of hearing, and operation time were evaluated. Results Ossiculoplasty was performed in four patients in the endoscopic group and two patients in the microscopic group. Lempert endaural incision II was used in all the patients in the microscopic group, whereas Lempert I incision was used in all the patients in the endoscopic approach group. There were no significant differences between the two groups regarding hearing improvement and operating time. And, there were no recurrences during the follow-up period in both groups. Conclusion The endoscopic approach for the management of attic cholesteatoma is as useful as the microscopic approach
Enhanced magnetic and thermoelectric properties in epitaxial polycrystalline SrRuO3 thin film
Transition metal oxide thin films show versatile electrical, magnetic, and
thermal properties which can be tailored by deliberately introducing
macroscopic grain boundaries via polycrystalline solids. In this study, we
focus on the modification of the magnetic and thermal transport properties by
fabricating single- and polycrystalline epitaxial SrRuO3 thin films using
pulsed laser epitaxy. Using epitaxial stabilization technique with atomically
flat polycrystalline SrTiO3 substrate, epitaxial polycrystalline SrRuO3 thin
film with crystalline quality of each grain comparable to that of
single-crystalline counterpart is realized. In particular, alleviated
compressive strain near the grain boundaries due to coalescence is evidenced
structurally, which induced enhancement of ferromagnetic ordering of the
polycrystalline epitaxial thin film. The structural variations associated with
the grain boundaries further reduce the thermal conductivity without
deteriorating the electronic transport, and lead to enhanced thermoelectric
efficiency in the epitaxial polycrystalline thin films, compared with their
single-crystalline counterpart.Comment: 24 pages, 5 figure
FEASIBILITY STUDY ON EFFECT OF STRUCTURAL FLEXIBILITY OF ASYMMETRIC PRE-SWIRL STATOR ON PROPULSION PERFORMANCE FOR KRISO CONTAINER SHIP (KCS)
The use of energy-saving devices is the most effective method for decreasing CO2 emissions, which is an increasingly concerning environmental issue. The asymmetric pre-swirl stator has been developed as an energy-saving device and has been successfully applied to various types of vessels. In the present study, a flexible material was applied to an asymmetric pre-swirl stator to determine the variation in the flow around stator and its efficiency. A fluid–structure interaction (FSI) analysis system was developed using the Star-CCM+ (fluid) and the Abaqus (structure). The proposed analysis system was validated by comparing the experimental results using a flexible plate in a flowing fluid. The flexible stator was applied to a 3,600 TEU KRISO Container Ship to determine the improvement in its performance compared to the previous optimum value achieved with a rigid stator. Although this application was conducted on a model scale and the deformation was small, the results of the flexible stator indicated the possibility of not only increasing the efficiency but also decreasing the vortex risk around stator blade
One-directional flow of ionic solutions along fine electrodes under an alternating current electric field
Electric fields are widely used for controlling liquids in various research fields. To control a liquid, an alternating current (AC) electric field can offer unique advantages over a direct current (DC) electric field, such as fast and programmable flows and reduced side effects, namely the generation of gas bubbles. Here, we demonstrate one-directional flow along carbon nanotube nanowires under an AC electric field, with no additional equipment or frequency matching. This phenomenon has the following characteristics: First, the flow rates of the transported liquid were changed by altering the frequency showing Gaussian behaviour. Second, a particular frequency generated maximum liquid flow. Third, flow rates with an AC electric field (approximately nanolitre per minute) were much faster than those of a DC electric field (approximately picolitre per minute). Fourth, the flow rates could be controlled by changing the applied voltage, frequency, ion concentration of the solution and offset voltage. Our finding of microfluidic control using an AC electric field could provide a new method for controlling liquids in various research fields
Spatio-Temporal Images of Single Streamer Propagation in Dielectric Barrier Discharge
One-dimensional time-dependent numerical simulations are presented to find the discharge mechanism and illustrate the spatio-temporal images of a single streamer in the dielectric barrier discharge (DBD). Calculated results reveal that the three discharge phases of avalanche, streamer, and decay are distinguished depending on the external voltage applied to the electrodes in the DBD. At different over-voltage conditions, the time evolutions of discharge currents show distinct profiles which
adequately explain the spatio-temporal variations of the single
streamer in the DBD
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