Two-dimensional Dirac plasmon-polaritons in graphene, 3D topological insulator and hybrid systems

Collective oscillations of massless particles in two-dimensional (2D) Dirac materials offer an innovative route toward implementing atomically thin devices based on low-energy quasiparticle interactions. Strong confinement of near-field distribution on the 2D surface is essential to demonstrate extraordinary optoelectronic functions, providing means to shape the spectral response at the mid-infrared (IR) wavelength. Although the dynamic polarization from the linear response theory has successfully accounted for a range of experimental observations, a unified perspective was still elusive, connecting the state-of-the-art developments based on the 2D Dirac plasmon-polaritons. Here, we review recent works on graphene and three-dimensional (3D) topological insulator (TI) plasmon-polariton, where the mid-IR and terahertz (THz) radiation experiences prominent confinement into a deep-subwavelength scale in a novel optoelectronic structure. After presenting general light-matter interactions between 2D Dirac plasmon and subwavelength quasiparticle excitations, we introduce various experimental techniques to couple the plasmon-polaritons with electromagnetic radiations. Electrical and optical controls over the plasmonic excitations reveal the hybridized plasmon modes in graphene and 3D TI, demonstrating an intense near-field interaction of 2D Dirac plasmon within the highly-compressed volume. These findings can further be applied to invent optoelectronic bio-molecular sensors, atomically thin photodetectors, and laser-driven light sources

Time-related Changes in Sleep-Wake Pattern as Correlates of Controlled Shift Work Rotating Directions

In order to elaborate the sleep-wake pattern changes manifested during controlled shift working of counterclockwise and clockwise rotations, eleven subjects were studied. A baseline sleep survey during uncontrolled shift working using a sleep questionnaire revealed that day and night shifts were found to have less total sleep time compared with evening and off duties, with delayed retire time in the evening shifts and advanced rise time in the day shifts. In analyses of data from controlled shift work schedules of opposite directions, difference in rise time appeared to be a crucial factor determining the total sleep time. This finding is compatible with the theory that rise time is one of the most powerful factors in resetting the biological clock. Retire time seemed to be determined more by the subjects' sleep habits and/or the socioenvironmental stimuli. Off-duty allocation was found to be an important variable in sleep-wake pattern modulation in shift working

Performance Improvement of a High Side Scroll Compressor by Thrust Surface Oil Groove

Performance analysis has been carried out on a high side scroll compressor having a fixed scroll equipped with a circular oil groove on its thrust surface. Oil is supplied to the oil groove through an intermittent opening from a high pressure oil reservoir formed inside the orbiting scroll hub. Oil in the groove is then delivered to both suction and back pressure chambers by pressure differentials and viscous pumping action of the orbiting scroll base plate. Mathematical modeling of this oil groove system has been incorporated into main compressor performance simulation program for optimum oil groove design. Pressure in the oil groove can be controlled by changing the oil passage area and oil groove configuration. With an enlarged oil passage, pressure in the oil groove increases due to increased flow rate, but pressure increase in the back pressure chamber is not that large, resulting in reduced friction loss at the thrust surface between the two scrolls. On the other hand, by increasing the oil passage area, oil content in the refrigerant flow increases, and the orbiting scroll stability could be negatively affected by oil groove pressure increase. Considering all these factors, EER could be improved by about 3.6% at ARI condition by optimum oil groove design

Evaluation of the pathogenicity of GJB3 and GJB6 variants associated with nonsyndromic hearing loss

AbstractA number of genes responsible for hearing loss are related to ion recycling and homeostasis in the inner ear. Connexins (Cx26 encoded by GJB2, Cx31 encoded by GJB3 and Cx30 encoded by GJB6) are core components of gap junctions in the inner ear. Gap junctions are intercellular communication channels and important factors that are associated with hearing loss. To date, a molecular genetics study of GJB3 and GJB6 as a causative gene for hearing loss has not been performed in Korea. This study was therefore performed to elucidate the genetic characteristics of Korean patients with nonsyndromic sensorineural hearing loss and to determine the pathological mechanism of hearing loss by analyzing the intercellular communication function of Cx30 and Cx31 variants. Sequencing analysis of the GJB3 and GJB6 genes in our population revealed a total of nine variants, including four novel variants in the two genes. Three of the novel variants (Cx31-p.V27M, Cx31-p.V43M and Cx-30-p.I248V) and two previously reported variants (Cx31-p.V84I and Cx30-p.A40V) were selected for functional studies using a pathogenicity prediction program and assessed for whether the mutations were located in a conserved region of the protein. The results of biochemical and ionic coupling tests showed that both the Cx31-p.V27M and Cx31-p.V84I variants did not function normally when each was expressed as a heterozygote with the wild-type Cx31. This study demonstrated that two variants of Cx31 were pathogenic mutations with deleterious effect. This information will be valuable in understanding the pathogenic role of GJB3 and GJB6 mutations associated with hearing loss

Titanium dioxide nanoparticles oral exposure to pregnant rats and its distribution

Background: Titanium dioxide (TiO2) nanoparticles are among the most manufactured nanomaterials in the industry, and are used in food products, toothpastes, cosmetics and paints. Pregnant women as well as their conceptuses may be exposed to TiO2 nanoparticles; however, the potential effects of these nanoparticles during pregnancy are controversial, and their internal distribution has not been investigated. Therefore, in this study, we investigated the potential effects of oral exposure to TiO2 nanoparticles and their distribution during pregnancy. TiO2 nanoparticles were orally administered to pregnant Sprague-Dawley rats (12 females per group) from gestation days (GDs) 6 to 19 at dosage levels of 0, 100, 300 and 1000 mg/kg/day, and then cesarean sections were conducted on GD 20. Results: In the maternal and embryo-fetal examinations, there were no marked toxicities in terms of general clinical signs, body weight, food consumption, organ weights, macroscopic findings, cesarean section parameters and fetal morphological examinations. In the distribution analysis, titanium contents were increased in the maternal liver, maternal brain and placenta after exposure to high doses of TiO2 nanoparticles. Conclusion: Oral exposure to TiO2 during pregnancy increased the titanium concentrations in the maternal liver, maternal brain and placenta, but these levels did not induce marked toxicities in maternal animals or affect embryo-fetal development. These results could be used to evaluate the human risk assessment of TiO2 nanoparticle oral exposure during pregnancy, and additional comprehensive toxicity studies are deemed necessary considering the possibility of complex exposure scenarios and the various sizes of TiO2 nanoparticles

Comparative Study of the Outcomes of Unilateral Biportal Endoscopic Discectomy and Tubular Microdiscectomy Based on the Visual Analogue Scale, Oswestry Disability Index, and Short-form 36

Objective Unilateral biportal endoscopic (UBE) discectomy and tubular microdiscectomy (TMD) are widely practiced methods for treatment of lumbar disc herniation. Good clinical outcomes of these methods are reported in many papers, but there are a few comparative studies. This study reports the clinical outcomes of UBE and TMD as minimally invasive surgery methods for lumbar disc herniations and discusses the effectiveness of UBE. Methods Sixty-seven patients who had undergone single-level discectomy using one of two methods, UBE or TMD, underwent a prospective follow-up examination. Thirty-four of these patients underwent discectomy using UBE, and the remaining 33 patients underwent TMD. In addition to the traditional measures of outcome, the improvement of generic health-related quality of life and disease-specific measurements like Visual Analogue Scale (VAS) score, Short-form 36 (SF-36), and Oswestry Disability Index (ODI) were evaluated and compared. Results Sixty-seven patients with more than 6 months of post-operative follow-up evaluations were included. The mean improvements in the VAS scores for back pain and leg pain and ODI were 2.0, 3.7, and 26.5 for the UBE group and 1.6, 3.0, and 19.4 for the TMD group. The SF-36 physical health component subscale score improved from 35.4 pre-operatively to 54.8 at the last follow-up in the UBE group, and the mental health score improved from 43.5 to 55.1 (TMD group: from 34.9 to 54.3 and 44.2 to 57.1, respectively). Conclusion The clinical outcomes of the UBE group are comparable to those of the TMD group. The results indicate that UBE for lumbar disc herniation can be performed safely and effectively as a treatment modality

Unusual transport characteristics of nitrogen-doped single-walled carbon nanotubes

Electrical transport characteristics of nitrogen-doped single-walled carbon nanotubes (N-SWCNTs), in which the nitrogen dopant is believed to form a pyridinelike bonding configuration, are studied with the field effect transistor operations. Contrary to the expectation that the nitrogen atoms may induce a n -type doping, the electrical transports through our N-SWCNTs are either ambipolar in vacuum or p -type in air. Through the first-principles electronic structure calculations, we show that the nitrogen dopant indeed favors the pyridinelike configuration and the Fermi level of the pyridinelike N-SWCNT is almost at the intrinsic level.open01

Fatigue Prediction of the Discharge Pipe in Reciprocating Compressor

In this paper, a fatigue prediction of the line discharge tube for reciprocating compressor being installed in a refrigerator was studied. The tube usually gets plenty of the repeated loads caused by the start and stop motion of a reciprocating compressor. There are two representative methods to predict the fatigue stress. At first the stress-life can be applied to the problem which takes a lot of repeated stress within the elastic strain range. Second is the strain-life method which can be used when it comes to the problem of a small repeated stress in the plastic strain range. This paper presents the stress-life method how the design parameters of a discharge pipe relate to the fatigue prediction and analyzes the co-relation between them