MOLECULAR DYNAMICS SIMULATION OF WATER BEHAVIOR AS A FUNCTION OF TEMPERATURES AND MONOMER NUMBERS IN NAFION 117

ABSTRACT The proton exchange membrane plays a critical role as an electrolyte for proton transports in the PEMFC. Generally, the membrane, such as Nafion 117, consists of a polytetrafluoroethylene (PTFE) backbone and side-chains terminated with a sulfonate group ( 3 SO − ). Operating the fuel cell, the membrane preferentially becomes hydrated by absorbing water. Then, the hydrogen atom on the 3 SO − part of the side-chain can detach from its own position and hop to the next 3 SO − site. The water management is the key to the efficient operation of the fuel cell, since the water content is the one of decisive factors for membrane's lifetime and efficient operations of fuel cells as well. In this report, we set up the molecular model for hydrated Nafion 117 and simulate the molecular movements for various temperatures and monomer numbers. Here, we obtain the mean square displacements of water molecules and estimate the selfdiffusion coefficients of water in the Nafion 117. Greek Symbol

Sensitivity of censored data analysis to determine the characteristic value of structural timber

In structural timber tests, unintended failure mechanisms occur frequently in specimens and their results are called censored data. There are two censored data analysis: censored maximum likelihood estimation (CMLE) and Kaplan–Meier (KM) method. In this study, the precision of the censored data analysis was investigated to determine the characteristic value, 5th percentile value, of the structural timber. The results show that (1) the 5th percentile value was underestimated by ordinary data analysis methods; maximum likelihood estimation (MLE) and Order statistics. (2) CMLE with 30% lower tail censored data and KM method provided much more precise 5th percentile value. (3) The amount of under-measurement (5 MPa, 10 MPa, and 15 MPa in this simulation study) did not show significant effect on the 5th percentile determination in CMLE and KM method, but the proportion of censored data (percentage of unintended failure specimen; 10%, 20%, 30%, and 40%) affected the determination of 5th percentile value. (4) CMLE with 30% lower tail censored data and KM method showed good agreement in case that the data included unintended failure data up to 20%.(1) This work was supported by Research Resettlement Fund for the new fac‑ulty of Seoul National University. (2) This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIT) (No. 2017R1A2B1010748)

Prediction of withdrawal resistance for a screw in hybrid cross-laminated timber

The aim of this study was to predict the withdrawal resistance of a screw in hybrid cross-laminated timber (CLT) composed of two types of lamina layers. A theoretical model to predict the withdrawal resistance was developed from the shear mechanism between a screw and the layers in hybrid CLT. The parameters for the developed model were the withdrawal stiffness and strength that occurs when a screw is withdrawn, and the penetration depth of a screw in layers of a wood material. The prediction model was validated with an experimental test. Screws with two different diameters and lengths (Ø6.5 × 65mm and Ø8.0 × 100mm) were inserted in a panel composed of solid wood and plywood layers, and the withdrawal resistances of the screws were evaluated. At least 30 specimens for each group were tested to derive the lower 5th percentile values. As a result, the developed model predictions were 86–88% of the lower 5th percentile values of hybrid CLT from the properties of the lamina layer. This shows that the withdrawal resistance of hybrid CLT can be designed from the properties of its layer.This project was funded by the Korea Forest Service (Korea Forestry Promotion Institute) and the Ministry of Land, Infrastructure and Transport (the Korea Agency for Infrastructure Technology Advancement)

Acute perimyocarditis mimicking acute myocardial infarction in a 12-year-old boy with Duchenne muscular dystrophy

Differential diagnosis of chest pain in the pediatric population is important but can be challenging. A 12-year-old boy with Duchenne muscular dystrophy presented with chest pain, cardiac enzyme elevation, and convex ST elevations in the inferior leads with reciprocal ST depression in the anterior leads on electrocardiogram. Echocardiography on admission revealed normal left ventricular function. Suspecting acute myocardial infarction, we performed invasive coronary angiography, which revealed normal coronary arteries. A follow-up electrocardiogram showed an acute pericarditis pattern with concave ST elevations in most leads and PR depression, and follow-up echocardiography revealed global left ventricular dysfunction, suggestive of acute perimyocarditis. Ibuprofen was administered for acute pericarditis, and a continuous milrinone infusion was commenced for myocardial dysfunction. The chest pain improved by the next day, and the ST segment elevations normalized on day 4. Echocardiography on day 9 revealed improved left ventricular function. The patient was discharged on day 11, and he is doing well without chest pain through 12 months of follow-up. The last electrocardiogram showed normal sinus rhythm without ST change. Differential diagnosis of acute myocardial infarction and acute perimyocarditis is important for proper treatment strategies and the different prognoses of these two conditions

Lateral resistance of mass timber shear wall connected by withdrawal-type connectors

In this study, the lateral resistances of mass timber shear walls were investigated for seismic design. The lateral resistances were predicted by kinematic models with mechanical properties of connectors, and compared with experimental data. Four out of 7 shear wall specimens consisted of a single Ply-lam panel and withdrawal-type connectors. Three out of 7 shear wall specimens consisted of two panels made by dividing a single panel in half. The divided panels were connected by 2 or 4 connectors like a single panel before being divided. The applied vertical load was 0, 24, or 120 kN, and the number of connectors for connecting the Ply-lam wall-to-floor was 2 or 4. As a result, the tested data were 6.3 to 52.7% higher than the predicted value by kinematic models, and it means that the lateral resistance can be designed by the behavior of the connector, and the prediction will be safe. The effects of wall-to-wall connectors, wall-to-floor connectors and vertical loads on the shear wall were analyzed with the experimental data.This project was funded by the Korea Forest Service (Korea Forestry Promotion Institute) and the Ministry of Land, Infrastructure and Transport (the Korea Agency for Infrastructure Technology Advancement)

Formate Dehydrogenase (FDH1) Localizes to Both Mitochondria and Chloroplast to Play a Role in Host and Nonhost Disease Resistance

Nonhost disease resistance is the most common type of plant defense mechanism against potential pathogens. In this study, the metabolic enzyme formate dehydrogenase (FDH1) was identified to be involved in nonhost disease resistance in Nicotiana benthamiana and Arabidopsis thaliana. In Arabidopsis, AtFDH1 was highly upregulated in response to both host and nonhost bacterial pathogens. Arabidopsis Atfdh1 mutants were compromised in nonhost resistance, basal resistance, and gene-for-gene resistance. The expression patterns of salicylic acid (SA) and jasmonic acid (JA) marker genes after pathogen infections in Atfdh1 mutant indicated that SA is most likely involved in the FDH1-mediated plant defense response to both host and nonhost bacterial pathogens. Previous studies reported that FDH1 localizes to only mitochondria, or both mitochondria and chloroplasts. Our results showed that the AtFDH1 localized to mitochondria and the amount of FDH1 localized to mitochondria increased upon infection with host or nonhost pathogens. Interestingly, the subcellular localization of FDH1 was observed in both mitochondria and chloroplasts after infection with a nonhost pathogen in Arabidopsis. We speculate that FDH1 plays a role in cellular signaling networks between mitochondria and chloroplasts to produce coordinated defense responses such as SA-induced reactive oxygen species (ROS) generation and hypersensitive response (HR)-induced cell death against nonhost bacterial pathogens

Cost-effectiveness of a medication event monitoring system for tuberculosis management in Morocco

BACKGROUND: Digital health technologies have been used to enhance adherence to TB medication, but the cost-effectiveness remains unclear. METHODS: We used the real data from the study conducted from April 2014 to December 2020 in Morocco using a smart pillbox with a web-based medication monitoring system, called Medication Event Monitoring Systems (MEMS). Cost-effectiveness was evaluated using a decision analysis model including Markov model for Multi-drug resistant (MDR) TB from the health system perspective. The primary outcome was the incremental cost-effectiveness ratio (ICER) per disability adjusted life-year (DALY) averted. Two-way sensitive analysis was done for the treatment success rate between MEMS and standard of care. RESULTS: The average total per-patient health system costs for treating a new TB patient under MEMS versus standard of care were $398.70 and$155.70, respectively. The MEMS strategy would reduce the number of drug-susceptible TB cases by 0.17 and MDR-TB cases by 0.01 per patient over five years. The ICER of MEMS was $434/DALY averted relative to standard of care, and was most susceptible to the TB treatment success rate of both strategies followed by the managing cost of MEMS. CONCLUSION: MEMS is considered cost-effective for managing infectious active TB in Morocco

Seroprevalence and risk factors of Besnoitia besnoiti infection in Korean cattle – short communication

Besnoitia besnoiti is an obligate intracellular parasite that is transmitted by direct contact or via mechanical transmission by flies as vectors. Besnoitiosis causes economic losses in the cattle industry and is regarded as a re-emerging disease in Europe. This study evaluated the seroprevalence of B. besnoiti in Korean cattle using a commercial ELISA kit. Among 558 serum samples, 19 (3.4%) tested seropositive for B. besnoiti. The statistically significant risk factors included age (≥ 2 years), sex (castrated males), and region (lower latitudes) (P < 0.05). The overall seroprevalence suggested a wide distribution of B. besnoiti infection in cattle reared in Korea. Thus, the practice of intensive cattle husbandry and the regionally different seroprevalence of B. besnoiti infection in cattle in Korea warrant routine monitoring and vector control to reduce economical losses due to bovine besnoitiosis in the country