5,572 research outputs found
Ni-dispersed fullerenes: Hydrogen storage and desorption properties
Our study shows that the H2 storage media using Ni-dispersed fullerenes could be viable alternatives to reversible hydrogen storage. It is demonstrated that a single Ni coated on the fullerene surface can store up to three H2 molecules. Consequently, at high Ni coverage, Ni-dispersed fullerenes are considered to be the novel hydrogen storage media capable of storing ~6.8 wt % H2, thus exceeding the Department of Energy target (6.5 wt %) for automobile applications. Moreover, the H2 desorption activation barrier of 11.8 kcal/mol H2 is ideal for many practical hydrogen storage applications
Vertically aligned InGaN nanowires with engineered axial In composition for highly efficient visible light emission.
We report on the fabrication of novel InGaN nanowires (NWs) with improved crystalline quality and high radiative efficiency for applications as nanoscale visible light emitters. Pristine InGaN NWs grown under a uniform In/Ga molar flow ratio (UIF) exhibited multi-peak white-like emission and a high density of dislocation-like defects. A phase separation and broad emission with non-uniform luminescent clusters were also observed for a single UIF NW investigated by spatially resolved cathodoluminescence. Hence, we proposed a simple approach based on engineering the axial In content by increasing the In/Ga molar flow ratio at the end of NW growth. This new approach yielded samples with a high luminescence intensity, a narrow emission spectrum, and enhanced crystalline quality. Using time-resolved photoluminescence spectroscopy, the UIF NWs exhibited a long radiative recombination time (Ï„r) and low internal quantum efficiency (IQE) due to strong exciton localization and carrier trapping in defect states. In contrast, NWs with engineered In content demonstrated three times higher IQE and a much shorter Ï„r due to mitigated In fluctuation and improved crystal quality
TESTING OF ROTATIONAL EXERCISE EQUIPMENT TO IMPROVE THE VESTIBULAR SYSTEM
The primary purpose of this study was to test the effect of training using the rotational exercise equipment developed in this study on the improvement of the vestibular system. In order to test the rotational exercise equipment developed in this study, 15 ordinary college students had trainings for 8 weeks and their nystagmus intensity was analyzed. The findings showed that the rotational training using the rotational exercise equipment affected vestibular balance, as it significantly decreased the slow phase velocity (SPV) immediately after rotational stimulation and reduced the recovery time of nystagmus to normal
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The Influence of Electron Beam Sterilization on In Vivo Degradation of β-TCP/PCL of Different Composite Ratios for Bone Tissue Engineering.
We evaluated the effect of electron beam (E-beam) sterilization (25 kGy, ISO 11137) on the degradation of β-tricalcium phosphate/polycaprolactone (β-TCP/PCL) composite filaments of various ratios (0:100, 20:80, 40:60, and 60:40 TCP:PCL by mass) in a rat subcutaneous model for 24 weeks. Volumes of the samples before implantation and after explantation were measured using micro-computed tomography (micro-CT). The filament volume changes before sacrifice were also measured using a live micro-CT. In our micro-CT analyses, there was no significant difference in volume change between the E-beam treated groups and non-E-beam treated groups of the same β-TCP to PCL ratios, except for the 0% β-TCP group. However, the average volume reduction differences between the E-beam and non-E-beam groups in the same-ratio samples were 0.76% (0% TCP), 3.30% (20% TCP), 4.65% (40% TCP), and 3.67% (60% TCP). The E-beam samples generally had more volume reduction in all experimental groups. Therefore, E-beam treatment may accelerate degradation. In our live micro-CT analyses, most volume reduction arose in the first four weeks after implantation and slowed between 4 and 20 weeks in all groups. E-beam groups showed greater volume reduction at every time point, which is consistent with the results by micro-CT analysis. Histology results suggest the biocompatibility of TCP/PCL composite filaments
Laterally coupled and field-induced quantum Hall systems
A quantum Hall system which is divided into two laterally coupled subsystems
by means of a tunneling barrier exhibits a complex Landau level dispersion.
Magnetotunneling spectroscopy is employed to investigate the small energy gaps
which separate subsequent Landau bands. The control on the Fermi level permits
to trace the anticrossings for varying magnetic fields. The band structure
calculation predicts a magnetic shift of the band gaps on the scale of the
cyclotron energy. This effect is confirmed experimentally by a displacement of
the conductance peaks on the axis of the filling factor. Tunneling centers
within the barrier are responsible for quantum interferences between opposite
edge channels. Due to the disorder potential, the corresponding Aharonov-Bohm
interferometers generate additional long-period and irregular conductance
features. In the regime of strong localization, conductance fluctuations occur
at small magnetic fields before the onset of the regular Landau oscillations.
The Landau dispersion is obtained by a dedicated algorithm which solves the
Schroedinger equation exactly for a single electron residing in a quantum Hall
system with an arbitrary unidirectional, threefold staircase potential.Comment: 20 pages, 11 figures, 1 table; v2: explanation added in section 2,
some minor change
The Association between Apolipoprotein A-II and Metabolic Syndrome in Korean Adults: A Comparison Study of Apolipoprotein A-I and Apolipoprotein B
BackgroundApolipoprotein A-II (apoA-II) is the second-most abundant apolipoprotein in human high-density lipoprotein and its role in cardio metabolic risk is not entirely clear. It has been suggested to have poor anti-atherogenic or even pro-atherogenic properties, but there are few studies on the possible role of apoA-II in Asian populations. The aim of this study is to evaluate the role of apoA-II in metabolic syndrome (MetS) compared with apolipoprotein A-I (apoA-I) and apolipoprotein B (apoB) in Korean adults.MethodsWe analyzed data from 244 adults who visited the Center for Health Promotion in Pusan National University Yangsan Hospital for routine health examinations.ResultsThe mean apoB level was significantly higher, and the mean apoA-I level was significantly lower, in MetS; however, there was no significant difference in apoA-II levels (30.5±4.6 mg/dL vs. 31.2±4.6 mg/dL, P=0.261). ApoA-II levels were more positively correlated with apoA-I levels than apoB levels. ApoA-II levels were less negatively correlated with homocysteine and high sensitivity C-reactive protein levels than apoA-I levels. The differences in MetS prevalence from the lowest to highest quartile of apoA-II were not significant (9.0%, 5.7%, 4.9%, and 6.6%, P=0.279). The relative risk of the highest quartile of apoA-II compared with the lowest quartile also was not significantly different (odds ratio, 0.96; 95% confidence interval, 0.95 to 1.04; P=0.956).ConclusionCompared with apoA-I (negative association with MetS) and apoB (positive association with MetS) levels, apoA-II levels did not show any association with MetS in this study involving Korean adults. However, apoA-II may have both anti-atherogenic and pro-atherogenic properties
THE EFFECTS OF WEARING SPANDEX WEAR WITH COMPRESSION BAND ON MUSCLE ACTIVITY DURING A GOLF SWING
The purpose of this study was to determine how spandex wear with compressive band affects muscle activities during a golf swing. This study showed that average and maximum nEMG (normalized EMG) values of left AO (external abdominal oblique) were less in EG (experimental group) compared with CG (control group) during back swing, whereas those of left PM (pectoralis major) in EG were greater than CG. It is more likely that EG performed effectively golf swing without excess muscle activity. Thus, the spandex wear with compressive band played an important role in improving swing
performance with injury prevention. This has led to suggestions of the need for further kinetic and kinematic analyses to evaluate its function
Posttraumatic Pseudoaneurysm in Scalp Treated by Direct Puncture Embolization Using N-Butyl-2-Cyanoacrylate: a Case Report
Here, we report a case of scalp pseudoaneurysm which was treated by direct puncture embolization using n-butyl-2-cyanoacrylate. The patient had a history of blunt trauma in the previous two months. Ultrasound-guided manual compression was initially attempted, but the results were unsatisfactory. Direct puncture embolization was then performed, and the pseudoaneurysm was completely obliterated. Non-surgical treatment options for pseudoaneurysm are briefly discussed
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