Ultrafast Carrier Dynamics at p-n Junction of Cu(In,Ga)Se2- Based Solar Cells Measured by Optical Pump Terahertz Probe Spectroscopy

Among other materials, the p-type Cu(In,Ga)Se2 (CIGS) alloy has attracted attention as the most efficient absorber in thin-film solar cells. The typical CIGS layer is deposited with a polycrystalline structure containing an amount of native defect states, which serve as carrier traps and recombination centers. These defect states in the CIGS layer can be easily changed after deposition of an n-type buffer layer, due to the formation of p-n junctions. To understand the influence of the p-n junction on these defect states, the behavior of photoexcited carriers, from the CIGS absorber to the buffer layer, is considered to be an important issue and is closely related to solar cell performance. In this study, we performed experiments to investigate the ultrafast carrier dynamics of CIGS-based solar cells, using optical pump terahertz (THz) probe (OPTP) spectroscopy, and demonstrated the correlation between solar cell performance and the behavior of photoexcited carrier dynamics

Institutional Change and Continuity in Koreas Central Agencies, 1948-2011

This article analyzes Koreas central agencies, which have been organized and reorganized to support presidential executive leadership since the foundation of the Republic. Each central agency has carried out the standardization of a core administrative function which is essential to the operation of administrative apparatuses, including policy planning and coordination, budgeting, organizing, staffing, legislation, public relations, central-local relations, control and performance evaluation, etc. The six decades of institutionalization can be characterized, based on the central agencies proportion of the total administrative apparatus, into three phases: high (more than 35 percent, 1948-1961), middle (around 20 percent, 1962-2007), and low (about 10 percent, 2008-present). Regardless of the changing size and organizational configuration of the central agencies, however, their roles and influence as core executive apparatuses have remained largely unchanged, especially since the early 1960s. More than 67 percent, on average, of the heads and deputy heads of CAs have been former public servants, less than 18 percent have been former politicians, and about 15percent have been former outside experts. This strong bureaucratic background has oriented Koreas core executive policy direction significantly toward longterm, consistent, and plan rationality rather than short-term, flexible, and democratic responsiveness

Linear Wave Reflection by Trench with Various Shapes

author's final versionTwo types of analytical solutions for waves propagating over an asymmetric trench are derived. One is a shallow water wave model and the other is an extended model applicable to deeper water. The water depth inside the trench varies in proportion to a power of distance from the center of the trench (where the center means the deepest water depth point and the origin of -coordinate in this study). The mild-slope equation is transformed into a second order ordinary differential equation with variable coefficients based on the longwave assumption or Hunts (1979) approximate solution for wave dispersion. The analytical solutions are then obtained by using the power series technique. The analytical solutions are compared with the numerical solution of the hyperbolic mild-slope equations. After obtaining the analytical solutions under various conditions, the results are analyzed

Quantitative agreement of Dzyaloshinskii-Moriya interactions for domain-wall motion and spin-wave propagation

The magnetic exchange interaction is the one of the key factors governing the basic characteristics of magnetic systems. Unlike the symmetric nature of the Heisenberg exchange interaction, the interfacial Dzyaloshinskii-Moriya interaction (DMI) generates an antisymmetric exchange interaction which offers challenging opportunities in spintronics with intriguing antisymmetric phenomena. The role of the DMI, however, is still being debated, largely because distinct strengths of DMI have been measured for different magnetic objects, particularly chiral magnetic domain walls (DWs) and non-reciprocal spin waves (SWs). In this paper, we show that, after careful data analysis, both the DWs and SWs experience the same strength of DMI. This was confirmed by spin-torque efficiency measurement for the DWs, and Brillouin light scattering measurement for the SWs. This observation, therefore, indicates the unique role of the DMI on the magnetic DW and SW dynamics and also guarantees the compatibility of several DMI-measurement schemes recently proposed.Comment: 24 pages, 5 figure

Health-related quality of life with KDQOL-36 and its association with self-efficacy and treatment satisfaction in Korean dialysis patients

BACKGROUND AND OBJECTIVES: This study was conducted to measure the level of health-related quality of life (HRQOL) and to reveal the association of self-efficacy and treatment satisfaction with it in Korean dialysis patients. DESIGN, SETTING, PARTICIPANTS, AND MEASUREMENTS: The study subjects were 237 patients receiving either hemodialysis (HD) or peritoneal dialysis (PD) from two university hospitals, from February to June in 2010. We investigated HRQOL using the Korean version of Kidney Disease Quality of Life Short Form 36 (KDQOL-36), and self-efficacy and treatment satisfaction by self-administrative questionnaire and their dialysis-related variables by reviewing clinical records. The associations of self-efficacy and treatment satisfaction with HRQOL were assessed using multiple linear regression analysis. RESULTS: The mean HRQOL results were as follows: Physical component score (PCS) was 39.1 ± 8.5, Mental component score (MCS) 44.6 ± 6.8, symptom/problem list was 67.6 ± 17.1, effects of disease score was 58.5 ± 19.6, and burden of disease score was 41.1 ± 28.4. Between PD and HD patients, we could find significant difference only in the symptom/problem list. After removing confounder’s effects by multivariate analysis, respectively, treatment goal self-efficacy and treatment management self-efficacy were significantly related with all 5 domains, except PCS. Treatment satisfaction was significantly related with PCS, MCS, and effects of kidney disease. CONCLUSIONS: Patients’ self-efficacy and treatment satisfaction could influence their HRQOL. Regular and systematic monitoring using KDQOL-36 and interventions to increase self-efficacy and treatment satisfaction should be considered in dialysis care in Korea

Subchronic oral toxicity of silver nanoparticles

<p>Abstract</p> <p>Background</p> <p>The antibacterial effect of silver nanoparticles has resulted in their extensive application in health, electronic, consumer, medicinal, pesticide, and home products; however, silver nanoparticles remain a controversial area of research with respect to their toxicity in biological and ecological systems.</p> <p>Results</p> <p>This study tested the oral toxicity of silver nanoparticles (56 nm) over a period of 13 weeks (90 days) in F344 rats following Organization for Economic Cooperation and Development (OECD) test guideline 408 and Good Laboratory Practices (GLP). Five-week-old rats, weighing about 99 g for the males and 92 g for the females, were divided into four 4 groups (10 rats in each group): vehicle control, low-dose (30 mg/kg), middle-dose (125 mg/kg), and high-dose (500 mg/kg). After 90 days of exposure, clinical chemistry, hematology, histopathology, and silver distribution were studied. There was a significant decrease (P < 0.05) in the body weight of male rats after 4 weeks of exposure, although there were no significant changes in food or water consumption during the study period. Significant dose-dependent changes were found in alkaline phosphatase and cholesterol for the male and female rats, indicating that exposure to more than 125 mg/kg of silver nanoparticles may result in slight liver damage. Histopathologic examination revealed a higher incidence of bile-duct hyperplasia, with or without necrosis, fibrosis, and/or pigmentation, in treated animals. There was also a dose-dependent accumulation of silver in all tissues examined. A gender-related difference in the accumulation of silver was noted in the kidneys, with a twofold increase in female kidneys compared to male kidneys.</p> <p>Conclusions</p> <p>The target organ for the silver nanoparticles was found to be the liver in both the male and female rats. A NOAEL (no observable adverse effect level) of 30 mg/kg and LOAEL (lowest observable adverse effect level) of 125 mg/kg are suggested from the present study.</p

Methane as an effective hydrogen source for single-layer graphene synthesis on Cu foil by plasma enhanced chemical vapor deposition

A single-layer graphene is synthesized on Cu foil in the absence of H2 flow by plasma enhanced chemical vapor deposition (PECVD). In lieu of an explicit H2 flow, hydrogen species are produced during methane decomposition process into their active species (CHx<4), assisted by the plasma. Notably, the early stage of growth depends strongly on the plasma power. The resulting grain size (the nucleation density) has a maximum (minimum) at 50 W and saturates when the plasma power is higher than 120 W because hydrogen partial pressures are effectively tuned by a simple control of the plasma power. Raman spectroscopy and transport measurements show that decomposed methane alone can provide sufficient amount of hydrogen species for high-quality graphene synthesis by PECVD.Comment: 22 pages, 6 figure

Subchronic inhalation toxicity of gold nanoparticles

<p>Abstract</p> <p>Background</p> <p>Gold nanoparticles are widely used in consumer products, including cosmetics, food packaging, beverages, toothpaste, automobiles, and lubricants. With this increase in consumer products containing gold nanoparticles, the potential for worker exposure to gold nanoparticles will also increase. Only a few studies have produced data on the <it>in vivo </it>toxicology of gold nanoparticles, meaning that the absorption, distribution, metabolism, and excretion (ADME) of gold nanoparticles remain unclear.</p> <p>Results</p> <p>The toxicity of gold nanoparticles was studied in Sprague Dawley rats by inhalation. Seven-week-old rats, weighing approximately 200 g (males) and 145 g (females), were divided into 4 groups (10 rats in each group): fresh-air control, low-dose (2.36 × 10⁴particle/cm³, 0.04 μg/m³), middle-dose (2.36 × 10⁵particle/cm³, 0.38 μg/m³), and high-dose (1.85 × 10⁶particle/cm³, 20.02 μg/m³). The animals were exposed to gold nanoparticles (average diameter 4-5 nm) for 6 hours/day, 5 days/week, for 90-days in a whole-body inhalation chamber. In addition to mortality and clinical observations, body weight, food consumption, and lung function were recorded weekly. At the end of the study, the rats were subjected to a full necropsy, blood samples were collected for hematology and clinical chemistry tests, and organ weights were measured. Cellular differential counts and cytotoxicity measurements, such as albumin, lactate dehydrogenase (LDH), and total protein were also monitored in a cellular bronchoalveolar lavage (BAL) fluid. Among lung function test measurements, tidal volume and minute volume showed a tendency to decrease comparing control and dose groups during the 90-days of exposure. Although no statistically significant differences were found in cellular differential counts, histopathologic examination showed minimal alveoli, an inflammatory infiltrate with a mixed cell type, and increased macrophages in the high-dose rats. Tissue distribution of gold nanoparticles showed a dose-dependent accumulation of gold in only lungs and kidneys with a gender-related difference in gold nanoparticles content in kidneys.</p> <p>Conclusions</p> <p>Lungs were the only organ in which there were dose-related changes in both male and female rats. Changes observed in lung histopathology and function in high-dose animals indicate that the highest concentration (20 μg/m³) is a LOAEL and the middle concentration (0.38 μg/m³) is a NOAEL for this study.</p

Clinical Characteristics and Long-Term Prognosis of Alport Syndrome: A Retrospective Single-Center Study

Purpose Alport syndrome (AS) is one of the most common inherited renal diseases caused due to mutations of genes encoding specific proteins of the type IV collagen family, and its major clinical manifestations include progressive renal failure, sensorineural deafness, and ocular abnormalities. We investigated the clinical characteristics and long-term prognosis of AS in Korean pediatric and adult populations. Methods We conducted a retrospective review of medical records of 33 children and adults who had been diagnosed or treated with AS from 1985 to 2019. Results The mean age of the 33 patients diagnosed with AS was 16.2±13.6 years, and the male-to-female ratio was 2:1. At the first visit, recurrent gross hematuria was the most common initial symptom. In 10 of 33 patients (30.3%), sensorineural hearing loss (SNHL) was diagnosed, but none had ophthalmic problems. Moreover, 11 of 33 patients (33.3%) had advanced to end-stage renal disease (ESRD), and a significant difference was observed in the age of the patients who progressed to ESRD based on the presence or absence of SNHL (P=0.035). Conclusion SNHL in AS can be an important prognostic factor for long-term deterioration of renal function. Further investigation is required to confirm the clinical course and the genetic characteristics of AS in Korea through prospective national cohort studies

A case of amoxicillin-induced hepatocellular liver injury with bile-duct damage

Amoxicillin, an antibiotic that is widely prescribed for various infections, is associated with a very low rate of drug-induced liver injury; hepatitis and cholestasis are rare complications. Here we present a case of a 39-year-old woman who was diagnosed with abdominal actinomycosis and received amoxicillin treatment. The patient displayed hepatocellular and bile-duct injury, in addition to elevated levels of liver enzymes. The patient was diagnosed with amoxicillin-induced cholestatic hepatitis. When amoxicillin was discontinued, the patient's symptoms improved and her liver enzyme levels reduced to near to the normal range