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Mixed phases of Fe3O4 and Fe5C2, interacting properly with SiO2, produce highly selective olefins from syngas.

Purpose : This study compares and analyzes the visual function systems with major developed countries related to set the direction for Korean optometrist and provide basic data for improving the system related to Korean visual function systems and preventive management of national eye health. Methods : The current operating systems of the three major countries of the WCO, which have led the leading development in world ophthalmology and optometry, were compared and analyzed through previous studies, literature, and internet data. Results : The current operating systems of the three major countries of the WCO, which have led the leading development in world ophthalmology and optometry, were compared and analyzed through previous studies, literature, and internet data. Conclusion : Major developed countries overseas are segmenting their workers in treatment and management of people with increased visual dysfunction due to various demands, supplying accurate and comfortable vision correction tools, preventing eye diseases, and strengthening expertise through various equipment. In addition, various forms of expenses are provided to the public to realize the welfare of the people's health, and employment stability of workers and experts related to the fourth and online industries is guaranteed through systems such as setting and supporting business expenses. more...

Dry reforming of methane (DRM) is an attractive route to simultaneously consume both methane (CH4) and carbon dioxide (CO2) for the production of valuable syngas. Although nickel catalysts are cons... more...

We developed a novel composite structure of MoS2 and naturally derived carbon as anode materials for lithium-ion batteries by using microalgae as both source materials and templates for nitrogen-doped hollow carbon with three dimensional internal structures. The microalgae-derived carbon performed the roles as conducting matrix and template for vertically stacked MoS2 nanosheets. The electrochemical performance of microalgae-derived carbon-MoS2 composite materials evaluated in half-cell system against lithium metal electrode secured capacity of 300 mA h/g after 880 cycles at current density of 5 A/g. We ascribe the excellent cycle performance to the unique structure of hollow spherical microalgae-derived carbon with rich inner structures and naturally doped nitrogen, which consequentially facilitate fast lithium ion transport. This kind of structuring strategy is advantageous in terms of utilizing naturally created structures of microbes with complexed inner organelles and trace of heteroatoms, not to mention in respect of producing value added material from biomass residues. more...

This study investigated the prevalence and comorbidities of attention deficit hyperactivity disorder (ADHD) among adults and children/adolescents in Korea.This study used data from the Korea Health Insurance Review and Assessment Service collected from 2008 to 2018. Study participants comprised patients with at least one diagnosis of ADHD (International Statistical Classification of Diseases and Related Health Provisions, 10th revision code F90.0). Prevalence rates and psychiatric comorbidities were also analyzed.We identified 878,996 patients diagnosed with ADHD between 2008 and 2018. The overall prevalence rate of diagnosed ADHD increased steeply from 127.1/100,000 in 2008 to 192.9/100,000 in 2018; it increased 1.47 times in children/adolescents (≤ 18 years) and 10.1 times in adults (＞ 18 years) during this period. Among adult and children/ adolescent ADHD patients, 61.84% (95% confidence interval [95% CI] 61.74-61.93) and 78.72% (95% CI 78.53- 78.91) had at least one psychiatric comorbidity, respectively.Our results showed that the prevalence rate of diagnosed ADHD has increased in Korea; however, it is lower than the global average. Further studies are required to identify and treat vulnerable populations appropriately. more...

Ni catalysts are most suitable for a steam methane reforming (SMR) reaction considering the activity and the cost, although coke formation remains the main problem. Here, Ni-based spinel catalysts with various Mg contents were developed through the synthesis of mesoporous Mg-aluminate supports by evaporation-induced self-assembly followed by Ni loading via incipient wetness impregnation. The mesoporous Ni/Mg-aluminate spinel catalysts showed high coke resistance under accelerated reaction conditions (0.0014 gcoke/gcat·h for Ni/Mg30, 0.0050 gcoke/gcat·h for a commercial catalyst). The coke resistance of the developed catalyst showed a clear trend: the higher the Mg content, the lower the coke deposition. The Ni catalysts with the lower Mg content showed a higher surface area and smaller Ni particle size, which originated from the difference of the sintering resistance and the exsolution of Ni particles. Despite these advantageous attributes of Ni catalysts, the coke resistance was higher for the catalysts with the higher Mg content while the catalytic activity was dependent on the reaction conditions. This reveals that the enhanced basicity of the catalyst could be the major parameter for the reduction of coke deposition in the SMR reaction. more...

Microalgal biofuel, albeit an exciting potential fossil-fuel-replacement candidate, still requires the development of more advanced downstream processing technology for its price competitiveness. The major challenge in a microalgae-based biorefinery is the efficient separation of microalgae from low-concentration culture broth. The post-harvesting cell-disruption step necessary to render microalgae suitable for lipid extraction, moreover, further raises energy consumption and cost. For the mitigation of biorefinery complexity and costs, we suggest herein a new scheme that integrates the critical downstream processes (harvesting and cell disruption) by means of cationic surfactant-decorated Fe3O4 nanoparticles. The cationic surfactants’ quaternary ammonium heads play an important role in not only flocculating negatively charged microalgae but also weakening thick cell walls. In the present study, the harvesting efficiency and cell-damaging effects of three cationic surfactants — cetrimonium bromide (CTAB), cetylpyridinium chloride (CPC), and cetylpyridinium bromide (CPB) — were evaluated. The CTAB-decorated Fe3O4 nanoparticles, which were found to be the most effective, achieved a 96.6% microalgae harvesting efficiency at a dosage of 0.46 g particle per g cell. Next, for the purposes of magnetic nanoparticle recycling and high-purity microalgal biomass obtainment, microalgae detachment from microalgae-Fe3O4 flocs was performed by addition of an anionic surfactant, sodium dodecyl sulfate (SDS). The detached CTAB-decorated Fe3O4 nanoparticles showed a steady reuse efficiency of about 80%. Furthermore, microalgae harvesting by CTAB-decorated Fe3O4 nanoparticles could contribute to a great improvement in the total extracted lipid content and greener wet extraction without the additional energy-intensive cell-disruption step, thus demonstrating the cell-disruption ability of CTAB-decorated Fe3O4 nanoparticles. more...

On-time Production & Delivery improvements through the Demand-Lot Pegging framework for a Semiconductor Business

Objective To conduct a meta-analysis from published studies to evaluate the relationship between long working hours and the risk of cardiovascular disease (CVD). Methods Among a total of 341 published studies found from publicly accessible databases, five cohort studies and six case-control studies were analyzed for the study. Results Statistically significant heterogeneity has been observed (P = 0.037). The effect of longer working hours was significantly associated with the risk of CVD in the random-effects model of all 11 studies (odds ratio, 1.37; 95% confidence interval, 1.11 to 1.70). On the basis of meta-regression analysis, the result was not affected by the mean age, region, or the study year. The P value using Eager test was 0.701 suggesting this analysis was unlikely to have any publication bias. Conclusions These findings provide evidence of increased CVD with long working hours. more...

There is inconsistency regarding the effects of cadmium exposure on liver function between the positive results found in animal studies and the negative results highlighted in epidemiological studies. We investigated whether environmental cadmium exposure is associated with an elevation in serum liver enzyme activity in Korean adults.This cross-sectional study evaluated adult participants without liver disease from the Korean National Health and Nutrition Examination Survey for 2008-2009. Multiple linear regression was conducted to investigate the association between blood cadmium concentration and the serum levels of aspartate aminotransferase (AST), alanine aminotransferase (ALT) and alkaline phosphatase (ALP) adjusting for age, sex, body mass index and the amount of alcohol consumption. Subjects were stratified into quartiles by their cumulative cadmium exposure rank. We estimated the multivariate-adjusted ORs for liver enzyme elevation using logistic regression models with the first quartile as the reference group.Total number of the subjects in the analysis was 3914. The blood cadmium concentrations were significantly associated with liver enzyme levels (AST, β=2.677, p value0.0001; ALT, β=3.696, p value0.0001; ALP, β=11.730, p value0.0001). As the cadmium levels approached higher quartiles, the ORs for an elevated AST, ALT and ALP was increased significantly.Environmental cadmium exposures are associated with an elevation in serum liver enzyme levels in Korean adults. more...

Water pipe network is installed underground and once equipped, it is difficult to recognize the state of pipes when the leak or burst happens. Accordingly, post management is often delayed after the fault occurs. Therefore, the systematic fault management system of water pipe network is required to prevent the accident and minimize the loss. In this work, we develop online fault detection system of water pipe network using data of pipes such as flow rate or pressure. The transient model describing water flow in pipelines is presented and simulated using MATLAB. The fault situations such as the leak or burst can be also simulated and flow rate or pressure data when the fault happens are collected. Faults are detected using statistical methods of fast Fourier transform and discrete wavelet transform, and they are compared to find which method shows the better fault detection performance., {"references":["E. B. Wylie, \"The Microcomputer and Pipeline Transients\", Journal of\nHydraulic Engineering, vol. 109, no. 12, pp. 1723-1739, 1983.","D. Misiunas, Failure Monitoring and Asset Condition Assessment in Water Supply Systems, Lund Univ., 1999.","E.K. Lada, J. C. Lu, and J. R. Wilson, \"A Wavelet-Based Procedure for\nProcess Fault Detection\", IEEE Transactions on Semiconductor Manufacturing,\nvol. 15, no. 1, pp. 79-90, 2002.","L. Satish, \"Short-time Fourier and Wavelet Transforms for Fault Detection\nin Power Transformers during Impulse Tests\", IEE Proc.-Sci. Meas. Technol., vol. 145, no. 2, pp. 77-84, 1998.","S. Bhunia, K. Roy, and J. Segura, \"A Novel Wavelet Transform Based\nTransient Current Analysis for Fault Detection and Localization\", DAC,\nvol. 25, no. 2, pp. 361-366, 2002."]} more...