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Polyhydroxybutyrate (PHB) is a bio-based, biodegradable and biocompatible plastic that has the potential to replace petroleum-based plastics. Lignocellulosic biomass is a promising feedstock for industrial fermentation to produce bioproducts such as polyhydroxybutyrate (PHB). However, the pretreatment processes of lignocellulosic biomass lead to the generation of toxic byproducts, such as furfural, 5-HMF, vanillin, and acetate, which affect microbial growth and productivity. In this study, to reduce furfural toxicity during PHB production from lignocellulosic hydrolysates, we genetically engineered Cupriavidus necator NCIMB 11599, by inserting the nicotine amide salvage pathway genes pncB and nadE to increase the NAD(P)H pool. We found that the expression of pncB was the most effective in improving tolerance to inhibitors, cell growth, PHB production and sugar consumption rate. In addition, the engineered strain harboring pncB showed higher PHB production using lignocellulosic hydrolysates than the wild-type strain. Therefore, the application of NAD salvage pathway genes improves the tolerance of Cupriavidus necator to lignocellulosic-derived inhibitors and should be used to optimize PHB production.

The field of radiochemistry in the Republic of Korea has expanded greatly over the last three decades to meet the rapid growth of technological demands in various areas such as nuclear energy and nuclear technologies for human health and environmental protection. Major research activities, which were initially centered at the Korea Atomic Energy Research Institute (KAERI), have gradually spread to major universities and the commercial sector. In this review, progress and recent research trends in nuclear and radiochemistry in Korea are summarized. The main research outcomes achieved by KAERI scientists are highlighted, with emphasis on basic actinide chemistry in nuclear fuel cycles, the radioanalytical chemistry of various radionuclides from radioactive waste and the environment, and medical radionuclide production. In addition, recent efforts to promote radiochemical education and future perspectives are briefly outlined.

The cellular activation of the NLRP3 inflammasome is spatiotemporally orchestrated by various organelles, but whether lysosomes contribute to this process remains unclear. Here, we show the vital role of the lysosomal membrane-tethered Ragulator complex in NLRP3 inflammasome activation. Deficiency of Lamtor1, an essential component of the Ragulator complex, abrogated NLRP3 inflammasome activation in murine macrophages and human monocytic cells. Myeloid-specific Lamtor1-deficient mice showed marked attenuation of NLRP3-associated inflammatory disease severity, including LPS-induced sepsis, alum-induced peritonitis, and monosodium urate (MSU)-induced arthritis. Mechanistically, Lamtor1 interacted with both NLRP3 and histone deacetylase 6 (HDAC6). HDAC6 enhances the interaction between Lamtor1 and NLRP3, resulting in NLRP3 inflammasome activation. DL-all-rac-α-tocopherol, a synthetic form of vitamin E, inhibited the Lamtor1-HDAC6 interaction, resulting in diminished NLRP3 inflammasome activation. Further, DL-all-rac-α-tocopherol alleviated acute gouty arthritis and MSU-induced peritonitis. These results provide novel insights into the role of lysosomes in the activation of NLRP3 inflammasomes by the Ragulator complex.

As part of the environmentally friendly policy of ships, active research is being conducted on energy storage systems (ESS) for ships. This ESS has a major influence on determining the propulsion and operation system of the ship in the future. A separate space must be provided for the ESS, but small and medium-sized ships often require it to be located at the bottom of the ship to make use of the available space. If the ESS is located at the bottom of the ship, the slamming impact load should be considered, and a study of the vibrations generated during the slamming impact is required. Ships are subjected to various environmental effects while sailing. Among them, the risk factor caused by waves is one of the direct risk factors for the operation of the ship. This slamming phenomenon affects not only ships but also offshore structures, and is a risk factor that can cause structural damage as well as damage to human life. Therefore, it is necessary to study the slamming load, and a method is needed to address it with a dynamic load instead of a static load. In order to reflect the slamming load in the design as a dynamic load rather than the equivalent hydrostatic pressure, which is a static load, it is necessary to study the elastic effect of the structure. The plate thickness is calculated by considering the equivalent design pressure based on the measured slamming pressure peak, and several experimental and theoretical studies have been conducted to estimate the exact value of the peak pressure. However, according to recent studies, structural damage is affected not only by the peak pressure but also by the peak width in the time interval of the peak pressure. Research on slamming has been ongoing for a long time, but structural damage due to slamming is still being reported steadily. In order to understand the slamming phenomenon and reflect it in the structural design formula, high-quality experimental results are required. The slamming phenomenon occurs in a very short time. In order to obtain high-quality experimental results for this slamming phenomenon, numerous experimental variables such as experimental equipment setting, appropriate sensor selection, and data measurement and storage capability must be carefully considered. Normally the slamming load can be expressed in terms of peak pressure, peak width, and duration of the pressure, and the maximum pressure and the idealized pressure value (impulse) are applied to the structure. This slamming pressure is affected by the shape and natural period of the structure and shows the largest pressure value when the dead-rise angle is 3° to 10°. In this study, the test was performed by repeatedly dropping into the water using structural bottom angles of 0°, 3°, 10°, and 20° to the free surface of the water. The peak pressure, peak width, impulse, pressure coefficient, and traveling velocity of peak pressure obtained from the repeated tests are estimated with mean and coefficient of variation.

This study describes the depth and straight motion control performance depending on control surface combinations of a supercavitating underwater vehicle. When an underwater vehicle experiences supercavitation, friction resistance can be minimized, thus achieving the effect of super-high-speed driving. Six degrees of freedom modeling of the underwater vehicle are performed and the guidance and control loops are designed with not only a cavitator and an elevator, but also a rudder and a differential elevator to improve the stability of the roll and yaw axis. The control performance based on the combination of control surfaces is analyzed by the root-mean-square error for keeping depth and straight motion.

89Zr is an emerging radionuclide with promising application in nuclear medicine for the non-invasive diagnosis of various cancers with PET imaging. This paper would discuss optimization efforts in the production of 89Zr carried out at Accelerator Radioisotope Development Team, Korea Atomic Energy Research Institute. Optimized conditions reveal high production yields of 89Zr ~ 37 ± 1.4 MBq/µA using 89Y(p,n)89Zr, ~ 12.7 MeV of proton, and 35 µA using yttrium coin target with indigenously constructed 30 MeV Cyclotron (RFT-30). Besides, the production optimization, quality control, and biological behavior of [89Zr]Zr-oxalate, chloride and, DFO demonstrated promising results.

A significant ecological problem was developed on disposing the enormous amounts of waste activated sludge (WAS) produced by traditional wastewater treatment. There have been various attempts recently originated to develop innovative methods for substantial sludge treatment. The most frequently used approach for treating sludge to produces methane and reduces sludge is anaerobic treatment. The hydrolysis phase in WAS limits the breakdown of complex macrobiotic compounds. The presence of extracellular polymeric substances (EPS) in biomass prevents the substrate from being hydrolyzed. Enhancing substrate hydrolysis involves removal of EPS preceded by phase separated pretreatment. Hence, a critical assessment of various phase separated pretreatment that has a remarkable effect on the anaerobic digestion process was documented in detail. Moreover, the economic viability and energy requirement of this treatment process was also discussed. Perspectives and recommendations for methane production were also provided to attain effectual sludge management.

The prediction of maneuverability is very important in the design process of an underwater vehicle. In this study, we predicted the steady turning ability of a symmetrical underwater vehicle while considering interactions between the yaw rate and drift/rudder angle through a simulation-based methodology. First, the hydrodynamic force and moment, including coupled derivatives, were obtained by computational fluid dynamics (CFD) simulations. The feasibility of CFD results were verified by comparing static drift/rudder simulations to vertical planar motion mechanism (VPMM) tests. Turning motion simulations were then performed by solving 2-degree-of-freedom (DOF) equations with CFD data. The turning radius, drift angle, advance, and tactical diameter were calculated. The results show good agreement with sea trial data and the effects on the turning characteristics of coupled interaction terms, especially between the yaw rate and drift angle.

A novel zeolite imidazole framework-8 (ZIF-8) composite was synthesized as an accelerator, and its effects on the physical properties of epoxies were examined. To prepare the new accelerator, fullerene was oxidized with 3-chloroperoxybenzoic acid under reflux for 5 h in toluene. The dried powder (fullerene oxide, C60(O)n) was reacted with AgNO3 solution to obtain the fullerene oxide-Ag nanoparticle composite C60(O)n–Ag, which was further reacted with ZIF-8 to afford the composite C60(O)n–Ag/ZIF-8. The composite was analyzed by X-ray diffraction, Fourier transform infrared spectroscopy, field emission scanning electron microscopy, and energy dispersive spectrometry. After the accelerator was added to the epoxy composites, the thermal curing properties were studied using differential scanning calorimetry. The composition was cured at a high temperature for subsequent physical tests, including dynamic mechanical analysis (DMA), transmission electron microscopy, and single overlap adhesion testing. The DMA results showed that the addition of C60(O)n–Ag/ZIF-8 to epoxy compositions resulted in an increase in tan δ by 11.5 °C, compared to that of the composition containing 2-methylimidazole (2MI) accelerator (147.2 °C). Furthermore, the single-lap shear strength test showed that the C60(O)n–Ag/ZIF-8 composition was 9.8% stronger (18.4 MPa) than that with 2MI (16.6 MPa).

Background and purpose Obstructive sleep apnea (OSA) is a modifiable risk factor for stroke, but there are limited data on which stroke subtypes are associated with OSA. The aim of this study was to assess the risk for wake-up stroke (WUS) associated with OSA according to each etiologic subtype to elucidate the pathophysiologic mechanism of OSA-associated stroke. Method We investigated 557 consecutive patients who were admitted with acute ischemic stroke in two regional comprehensive stroke centers using a standardized protocol including the Berlin questionnaire to identify symptoms of OSA prior to stroke. The collected stroke data included the time of onset, risk factors, and etiologic subtype. Stratified analysis according to sex was conducted because sex has been reported to be an effect modifier of OSA on cardiovascular outcomes. The association between preexisting OSA symptoms and WUS depending on etiologic subtypes was assessed using multivariate logistic regression analysis. Results Preexisting OSA symptoms were associated with the risk of overall WUS in men. Snoring was associated with WUS in large artery atherosclerosis [adjusted odds ratio, 2.67 (1.15–6.23)], and apnea was associated with WUS in small vessel occlusion [adjusted odds ratio, 8.21 (1.15–58.53)], whereas OSA symptoms were not significantly associated with WUS in cardioembolism. Associations between OSA and WUS were not found in women. Conclusion This study demonstrated the differential influences of OSA on WUS depending on etiologic subtypes, suggesting more vulnerability in large artery atherosclerosis and small vessel occlusion. Sex is a significant effect modifier of the association between OSA and WUS.

The purpose of this study is to predict the collision clearance distance of stereotactic cones with treatment setup devices in cone‐based stereotactic radiosurgery (SRS). The BrainLAB radiosurgery system with a Frameless Radiosurgery Positioning Array and dedicated couch top was targeted in this study. The positioning array and couch top were scanned with CT simulators, and their outer contours of were detected. The minimum clearance distance was estimated by calculating the Euclidian distances between the surface of the SRS cones and the nearest surface of the outer contours. The coordinate transformation of the outer contour was performed by incorporating the Beam's Eye View at a planned arc range and couch angle. From the minimum clearance distance, the collision‐free gantry ranges for each couch angle were sequentially determined. An in‐house software was developed to calculate the clearance distance between the cone surface and the outer contours, and thus determine the occurrence of a collision. The software was extensively tested for various combinations of couch and arc angles at multiple isocenter locations for two combinations of cone‐couch systems. A total of 50 arcs were used to validate the calculation accuracies of the software for each system. The calculated minimum distances and collision‐free angles from the software were verified by physical measurements. The calculated minimum distances were found to agree with the measurements to within 0.3 ± 0.9 mm. The collision‐free arc angles from the software also agreed with the measurements to within 1.1 ± 1.1° with a 5‐mm safety margin for 20 arcs. In conclusion, the in‐house software was able to calculate the minimum clearance distance with