A Method for Estimating Time-Dependent Corrosion Depth of Carbon and Weathering Steel Using an Atmospheric Corrosion Monitor Sensor.

In this study, a time-dependent corrosion depth estimation method using atmospheric corrosion monitor (ACM) sensor data to evaluate time-dependent corrosion behaviors is proposed. For the time-dependent corrosion depth estimation of uncoated carbon steel and weathering steel, acceleration corrosion tests were conducted in salt-spray corrosion environments and evaluated with a corrosion damage estimation method using ACM sensing data and corrosion loss data of the tested steel specimens. To estimate the time-dependent corrosion depth using corrosion current by an ACM sensor, the relationship between the mean corrosion depth calculated from the weight loss method and the corrosion current was evaluated. The mean corrosion depth was estimated by calculating the corrosion current and evaluating the relationship between the mean corrosion depth and corrosion current during the expected period. From the test and estimation results, the corrosion current demonstrated a good linear correlation with the mean corrosion depth of carbon steel and weathering. The calculated mean corrosion depth is nearly the same as that of the tested specimen, which can be well used to estimate corrosion rate for the uncoated carbon steel and weathering steel.

Optical detection of paraoxon using single-walled carbon nanotube films with attached organophosphorus hydrolase-expressed Escherichia coli.

In whole-cell based biosensors, spectrophotometry is one of the most commonly used methods for detecting organophosphates due to its simplicity and reliability. The sensor performance is directly affected by the cell immobilization method because it determines the amount of cells, the mass transfer rate, and the stability. In this study, we demonstrated that our previously-reported microbe immobilization method, a microbe-attached single-walled carbon nanotube film, can be applied to whole-cell-based organophosphate sensors. This method has many advantages over other whole-cell organophosphate sensors, including high specific activity, quick cell immobilization, and excellent stability. A device with circular electrodes was fabricated for an enlarged cell-immobilization area. Escherichia coli expressing organophosphorus hydrolase in the periplasmic space and single-walled carbon nanotubes were attached to the device by our method. Paraoxon was hydrolyzed using this device, and detected by measuring the concentration of the enzymatic reaction product, p-nitrophenol. The specific activity of our device was calculated, and was shown to be over 2.5 times that reported previously for other whole-cell organophosphate sensors. Thus, this method for generation of whole-cell-based OP biosensors might be optimal, as it overcomes many of the caveats that prevent the widespread use of other such devices.

Characterization of a new selective glucocorticoid receptor modulator with anorexigenic activity.

Obesity, a worldwide epidemic, leads to various metabolic disorders threatening human health. In response to stress or fasting, glucocorticoid (GC) levels are elevated to promote food intake. This involves GC-induced expression of the orexigenic neuropeptides in agouti-related protein (AgRP) neurons of the hypothalamic arcuate nucleus (ARC) via the GC receptor (GR). Here, we report a selective GR modulator (SGRM) that suppresses GR-induced transcription of genes with non-classical glucocorticoid response elements (GREs) such as Agrp-GRE, but not with classical GREs, and via this way may serve as a novel anti-obesity agent. We have identified a novel SGRM, 2-O-trans-p-coumaroylalphitolic acid (Zj7), a triterpenoid extracted from the Ziziphus jujube plant, that selectively suppresses GR transcriptional activity in Agrp-GRE without affecting classical GREs. Zj7 reduces the expression of orexigenic genes in the ARC and exerts a significant anorexigenic effect with weight loss in both high fat diet-induced obese and genetically obese db/db mouse models. Transcriptome analysis showed that Zj7 represses the expression of a group of orexigenic genes including Agrp and Npy induced by the synthetic GR ligand dexamethasone (Dex) in the hypothalamus. Taken together, Zj7, as a selective GR modulator, showed beneficial metabolic activities, in part by suppressing GR activity in non-classical GREs in orexigenic genes. This study demonstrates that a potential anorexigenic molecule may allow GRE-specific inhibition of GR transcriptional activity, which is a promising approach for the treatment of metabolic disorders.

Euscaphic acid isolated from roots of Rosa rugosa inhibits LPS-induced inflammatory responses via TLR4-mediated NF-κB inactivation in RAW 264.7 macrophages.

As an attempt to search for bioactive natural products exerting anti-inflammatory activity, we have evaluated the anti-inflammatory effects of euscaphic acid (19α-hydroxyursane-type triterpenoids, EA) isolated from roots of Rosa rugosa and its underlying molecular mechanisms in lipopolysaccharide (LPS)-induced RAW 264.7 macrophages. EA concentration-dependently reduced the production of nitric oxide (NO), prostaglandin E2 (PGE2), tumor necrosis factor-α (TNF-α), and interleukin-1ß (IL-1ß) induced by LPS in RAW 264.7 macgophages. Consistent with these data, expression levels of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) protein and iNOS, COX-2, TNF-α, and IL-1ß mRNA were inhibited by EA in a concentration-dependent manner. In addition, EA attenuated LPS-induced DNA binding and transcriptional activity of nuclear factor-kappa B (NF-κB), which was accompanied by a parallel reduction of degradation and phosphorylation of inhibitory kappa Bα (IκBα) and consequently by decreased nuclear translocation of p65 subunit of NF-κB. Pretreatment with EA significantly inhibited the LPS-induced phosphorylation of IκB kinase ß (IKKß), p38, and JNK, whereas the phosphorylation of ERK1/2 was unaffected. Furthermore, EA interfered with the LPS-induced clustering of TNF receptor-associated factor 6 (TRAF6) with interleukin receptor associated kinase 1 (IRAK1) and transforming growth factor-ß-activated kinase 1 (TAK1). Taken together, these results suggest that EA inhibits LPS-induced inflammatory responses by interference with the clustering of TRAF6 with IRAK1 and TAK1, resulting in blocking the activation of IKK and MAPKs signal transduction to downregulate NF-κB activations.

Aeroallergen Sensitization Status in South Korea From 2018 to 2021.

OBJECTIVES: Studies on the aeroallergen sensitization status of South Koreans based on large-scale data are lacking. METHODS: We analyzed data from 368,156 multiple allergosorbent tests collected by a domestic medical diagnosis company from 3,735 hospitals nationwide from 2018 to 2021. We additionally collected sex, age, and regional data. If the level of an aeroallergen was 0.35 IU/mL or more, the test result for that aeroallergen was defined as positive, and positive cases were defined as those where one aeroallergen was positive. The positive ratio (PR) for aeroallergens was calculated using positive cases. RESULTS: In total, 347,996 cases were analyzed, excluding cases with missing data. The percentage of positive cases was 56.7%, which was highest in adolescents (74.1%) and lowest in the elderly (47.0%). All four types of mites had high PRs (0.382-0.655), and mold had low PRs (0.023-0.058). Among pollens, the PRs of grasses were generally high (more than 0.14), followed by weeds (approximately 0.10), and the PRs of woods was less than 0.1. For animals, cats and dogs had the highest PRs, at 0.231 and 0.183, respectively. The value for cockroaches was also high, at 0.211. The PRs of indoor aeroallergens, such as mites, molds, and animals, were high in adolescents, and those of pollen and cockroaches were high in the elderly. In Jeju, the PR of Japanese cedars was extremely high (0.222). CONCLUSION: Koreans were found to be sensitized to a wide variety of aeroallergens. There were significant differences in sensitization patterns according to age and region.

Characteristics of wasteform composing of phosphate and silicate to immobilize radioactive waste salts.

In the radioactive waste management, metal chloride wastes from a pyrochemical process is one of problematic wastes not directly applicable to a conventional solidification process. Different from a use of minerals or a specific phosphate glass for immobilizing radioactive waste salts, our research group applied an inorganic composite, SAP (SiO(2)-Al(2)O(3)-P(2)O(5)), to stabilize them by dechlorination. From this method, a unique wasteform composing of phosphate and silicate could be fabricated. This study described the characteristic of the wasteform on the morphology, chemical durability, and some physical properties. The wasteform has a unique "domain-matrix" structure which would be attributed to the incompatibility between silicate and phosphate glass. At higher amounts of chemical binder, "P-rich phase encapsulated by Si-rich phase" was a dominant morphology, but it was changed to be Si-rich phase encapsulated by P-rich phase at a lower amount of binder. The domain and subdomain size in the wasteform was about 0.5-2 µm and hundreds of nm, respectively. The chemical durability of wasteform was confirmed by various leaching test methods (PCT-A, ISO dynamic leaching test, and MCC-1). From the leaching tests, it was found that the P-rich phase had ten times lower leach-resistance than the Si-rich phase. The leach rates of Cs and Sr in the wasteform were about 10(-3)g/m(2)· day, and the leached fractions of them were about 0.04% and 0.06% at 357 days, respectively. Using this method, we could stabilize and solidify the waste salt to form a monolithic wasteform with good leach-resistance. Also, the decrease of waste volume by the dechlorination approach would be beneficial in the final disposal cost, compared with the present immobilization methods for waste salt.

Effect of the nanosized TiO2 particles in Pd/C catalysts as cathode materials in direct methanol fuel cells.

Pd-TiO2/C catalysts were prepared by impregnating titanium dioxide (TiO2) on carbon-supported Pd (Pd/C) for use as the catalyst for the oxygen reduction reaction (ORR) in direct methanol fuel cells (DMFCs). Transmission electron microscope (TEM), scanning electron microscope (SEM) and X-ray diffraction (XRD) analyses were carried to confirm the distribution, morphology and structure of Pd and TiO2 on the carbon support. In fuel cell test, we confirmed that the addition of TiO2 nanoparticles make the improved catalytic activity of oxygen reduction. The electrochemical characterization of the Pd-TiO2/C catalyst for the ORR was carried out by cyclic voltammetry (CV) in the voltage window of 0.04 V to 1.2 V with scan rate of 25 mV/s. With the increase in the crystallite size of TiO2, the peak potential for OH(ads) desorption on the surface of Pd particle shifted to higher potential. This implies that TiO2 might affect the adsorption and desorption of oxygen molecules on Pd catalyst. The performance of Pd-TiO2/C as a cathode material was found to be similar to or better performance than that of Pt/C.

Performance of PtPd electrocatalysts in direct methanol fuel cell.

PtPd nanoparticles on carbon black were prepared to investigate the role of Pd in the anode and cathode of a direct methanol fuel cell (DMFC). The PtPd catalysts in the anode showed a significantly lower performance than the PtRu catalyst. However, the cell performances of these catalysts in the cathode were comparable to that of the Pt catalyst. From cyclic voltammetry, it was observed that the Pd with the Pt catalyst lowered the peak potential and increased the coulombic charge for oxide reduction on the surface of the catalyst. Also, the Pd catalyst without Pt showed relatively high activity for oxygen reduction reaction.

Anthropogenic gadolinium in lakes and rivers near metrocities in Korea.

We measured dissolved rare earth elements (REEs) in the water samples from Shihwa Lake (SL), which was assumed to be highly polluted, and in the downstream portion of the Han River (HR), which runs through Seoul, Korea. Among the investigated REEs, only gadolinium (Gd) was found to be significantly enhanced after REE concentrations were shale-normalized (SN). The calculated Gd anomaly (Gd/Gd* = 3 × GdSN/(SmSN + 2 × TbSN)) was about 1.5 ± 0.1 (n = 16) in SL and 1.6 ± 0.3 in the HR (n = 26) water relative to other types of natural water such as groundwater, seawater, and river water in uncontaminated areas (Gd/Gd* ∼ 1.2, n > 400). These significant Gd anomalies seem to be due to the inputs of anthropogenic Gd (Gdanth), especially from the use of Gd-based contrast agents for magnetic resonance imaging (MRI) tests from a number of hospitals and medical institutes surrounding our study areas. The amount of Gdanth was estimated to be 190 ± 80 g and 680 ± 360 kg Gd in SL and the HR (watersheds in our study area), respectively. The Gdanth flux to the Yellow Sea from the HR is estimated to be 530 ± 330 g Gd d-1. These results suggest that quantitative evaluation of anthropogenic REEs in natural waters near big cities is needed, because considerable amounts of REEs are now used by modern high-tech industries.

Residual Compressive Strength of Short Tubular Steel Columns with Artificially Fabricated Local Corrosion Damage.

Corrosion is considered as one of the main factors in the structural performance deterioration of steel members. In this study, experimental and numerical methods were used to assess the reduction in compressive strength of short tubular steel columns with artificially fabricated local corrosion damage. The corrosion damage was varied with different depths, heights, circumferences, and locations along the column. A parametric numerical study was performed to establish a correlation between the residual compressive strength and the severity of corrosion damage. The results showed that as the corrosion depth, height and circumference increased, the compressive strength decreased linearly. As for the corrosion height, the residual compressive strength became constant after decreasing linearly when the corrosion height was greater than the half-wavelength of buckling of the short columns. An equation is presented to evaluate the residual compressive strength of short columns with local corrosion wherein the volume of the corrosion damage was used as a reduction factor in calculating the compressive strength. The percentage error using the presented equation was found to be within 11.4%.

Distribution and accumulation of artificial radionuclides in marine products around Korean Peninsula.

We investigated the distributions of the artificial radionuclides 137Cs, 239+240Pu, and 90Sr in the various marine products around Korean Peninsula collected in 2015-2017. The activities of 137Cs, 239+240Pu, and 90Sr were in the ranges of 12.2-258.4 mBq kg-1, 0.014-1.879 mBq kg-1, and 11.3-18.3 mBq kg-1, respectively. The higher 239+240Pu (a factor of 10-50) relative to fishes were observed in mollusks. 137Cs in fishes were significantly enriched with growths. The calculated concentration factors (CFs) of 137Cs, 239+240Pu, and 90Sr in marine products were 7-143, 3-407, and 15-25, respectively. Overall, no noticeable artificial radioactivity was detected in marine organisms when comparing these results with previous data reported before the Fukushima nuclear accident and recommended CF values. The annual effective doses of 137Cs, 239+240Pu, and 90Sr by seafood consumption in South Korea were estimated to be 1.1 × 10-4, 1.6 × 10-5 and, 2.9 × 10-5 mSv yr-1, respectively, which is insignificant relative to that of natural radionuclides.

Unexpectedly high dimethyl sulfide concentration in high-latitude Arctic sea ice melt ponds.

Dimethyl sulfide (DMS) production in the northern Arctic Ocean has been considered to be minimal because of high sea ice concentration and extremely low productivity. However, we found DMS concentration (1-33 nM) in melt ponds on sea ice at a very high latitude (78°N) in the central Arctic Ocean to be up to ten times that in the adjacent open ocean (<3 nM). We divided melt ponds into three categories: freshwater melt ponds, brackish melt ponds, and open saline melt ponds. Melt ponds from each category had different formation mechanisms and associated DMS contents. Closed brackish ponds (salinity of >20) had particularly high DMS concentration. Water in brackish ponds was mixed with open ocean water in the past via a hole at the bottom of the floe that kept the pond open to the ocean; therefore, unlike freshwater melt ponds, brackish ponds became sites of DMS accumulation. Our results suggest that continuous increase in melt pond coverage on Arctic sea ice could considerably impact future Arctic climate as well as enhancing DMS concentration in the Arctic atmosphere.

Synthesis and characterization of Pt-Pd catalysts for methanol oxidation and oxygen reduction.

Pt-Pd nanoparticles supported on carbon black were prepared and characterized as electrocatalysts for methanol oxidation and oxygen reduction in an acidic solution. The Pt and Pd nanoparticles were impregnated spontaneously on the carbon black through a simple reducing process. X-ray diffraction, transmission electron microscopy, and electrochemical measurement were carried out to characterize the crystal structure, particle size, and catalytic activities of the Pt-Pd catalysts. The results showed that the Pt-Pd catalysts had higher catalytic activities for methanol oxidation reaction than pure Pt catalysts. The catalytic activity of the Pt-Pd catalysts for oxygen reduction reactions in the presence of methanol was higher than that of pure Pt and Pd. These results indicate that the Pt-Pd catalysts are suitable as electrocatalysts of both the anode and the cathode in direct methanol fuel cells.

Synthesis and Irreversible Thermochromic Sensor Applications of Manganese Violet.

An irreversible thermochromic material based on manganese violet (MnNH4P2O7) is synthesized. The crystal phase, chemical composition, and morphology of the synthesized material are analyzed using X-ray diffraction, scanning electron microscopy coupled with energy-dispersive X-ray spectrometry, and Fourier-transform infrared spectroscopy. The absorption spectra of the synthesized material are obtained using a UV-Vis spectrometer, and the thermochromism exhibited by the powdered samples at high temperatures is also investigated. The as-synthesized manganese violet pigment consists of pure α-MnNH4P2O7 phase. In addition, the synthesized pigment largely consists of hexagonal crystals with a diameter of hundreds of nanometers. On heating, the pigment simultaneously loses H2O and NH3 in two successive steps at approximately 330⁻434.4 °C and 434.4⁻527 °C, which correspond to the formation of an intermediate phase and of Mn2P4O12, respectively. An overall mass loss of 14.22% is observed, which is consistent with the expected 13.79%. An irreversible color change from violet to white is observed after exposure of the synthesized manganese violet pigment at 400 °C for 30 min. This is attributed to the oxidation of ammonia to hydroxylamine, which then decomposes to nitrogen and water, or alternatively to the direct oxidation of ammonia to nitrogen. Furthermore, we demonstrate the potential application of synthesized manganese violet in the production of irreversible thermochromic paint by mixing with potassium silicate solution as a binder and deionized water as a solvent at a specific ratio. The thermochromic paint is then applied in fabrication of irreversible thermochromic sensors by coating it onto a steel plate surface. Finally, we show that manganese violet-based irreversible thermochromic sensors are able to detect temperatures around 400 °C by changing color from violet to white/milky.

Anti-inflammatory activities of ent-16alphaH,17-hydroxy-kauran-19-oic acid isolated from the roots of Siegesbeckia pubescens are due to the inhibition of iNOS and COX-2 expression in RAW 264.7 macrophages via NF-kappaB inactivation.

To isolate the anti-inflammatory components in Siegesbeckia pubescens root, we performed activity-guided fractionation using a carrageenan-induced edema rat model. Antinociceptive effects were followed using acetic acid-induced abdominal constriction and hot plate tests in mice. Chloroform extract was subjected to silica gel and octadesyl silane (ODS) column chromatography, and a diterpene was isolated which was identified as ent-16alphaH,17-hydroxy-kauran-19-oic acid (siegeskaurolic acid). Pretreatment with siegeskaurolic acid (20 or 30 mg/kg/day, p.o.) exhibited anti-inflammatory and antinociceptive effects in these animal models. To investigate the mechanisms underlying this anti-inflammatory action, we investigated the effect of siegeskaurolic acid on lipopolysaccharide (LPS)-induced responses in a murine macrophage cell line, RAW 264.7. Siegeskaurolic acid was found to significantly inhibit the productions of nitric oxide (NO), prostaglandin E(2) (PGE(2)), and tumor necrosis factor-alpha (TNF-alpha). Consistent with these findings, inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) proteins, and iNOS, COX-2, and TNF-alpha mRNAs were found to be inhibited by siegeskaurolic acid. Furthermore, siegeskaurolic acid inhibited the nuclear factor-kappaB (NF-kappaB) activation induced by LPS, and this was associated with the prevention of inhibitor kappaB degradation (I kappaB), and subsequently with decreased nuclear p65 and p50 protein levels. Taken together, our data indicate that the anti-inflammatory and antinociceptive properties of siegeskaurolic acid may be due to iNOS, COX-2 and TNF-alpha inhibition via the down-regulation of NF-kappaB binding activity.

Development of a continuous electrolytic system with discharging only one pH-controlled stream and its characteristics.

In order to produce only a pH-controlled solution without discharging any unused solution, this work has developed a continuous electrolytic system with an ion exchange membrane-equipped electrolyzer and a tank, called as a pH-adjustment reservoir, placed just in front of the electrolyzer, where as a target solution was fed into the pH-adjustment reservoir, a portion of the solution in the pH-adjustment reservoir was circulated through the cathodic or anodic chamber of the electrolyzer depending on the type of the ion exchange membrane used, and another portion of the solution in the pH-adjustment reservoir was discharged from the electrolytic system through the opposite electrode chamber with its pH being controlled. The internal circulation of the pH-adjustment reservoir solution through the anodic chamber in the case of using a cation exchange membrane and that through the cathodic chamber in the case of using an anion exchange membrane could make the solution, discharged from the other counter chamber, effectively acidic and basic, respectively. The phenomena of the pH being controlled in the system could be explained by the electro-migration of the ion species in the solution through the ion exchange membrane under a cell potential difference between the anode and the cathode and its consequently-occurring non-charge equilibriums and the electrolytic water-split reactions in the anodic and cathodic chambers.

Synthesis and Thermochromic Properties of Cr-Doped Al2O3 for a Reversible Thermochromic Sensor.

An inorganic thermochromic material based on Cr-doped Al2O3 is synthesized using a solid-state method. The crystal structure, chemical composition, and morphology of the synthesized material are analyzed using X-ray diffraction, scanning electron microscopy coupled with an energy-dispersive X-ray spectrometer, and Fourier transform infrared (FT-IR) spectroscopy. The color performances of the synthesized material are analyzed using a UV-VIS spectrometer. Finally, the thermochromism exhibited by the powdered samples at high temperatures is investigated. The material exhibits exceptional thermochromic property, transitioning from pink to gray or green in a temperature range of 25-600 °C. The change in color is reversible and is dependent on the surrounding temperature and chromium concentration; however, it is independent of the exposure time. This novel property of Cr-doped Al2O3 can be potentially employed in reversible thermochromic sensors that could be used not only for warning users of damage due to overheating when the environmental temperature exceeds certain limits, but also for detecting and monitoring the temperature of various devices, such as aeronautical engine components, hotplates, and furnaces.

Characteristics of the horizontal and vertical distributions of dimethyl sulfide throughout the Amundsen Sea Polynya.

We investigated horizontal and vertical distributions of DMS in the upper water column of the Amundsen Sea Polynya and Pine Island Polynya during the austral summer (January-February) of 2016 using a membrane inlet mass spectrometer (MIMS) onboard the Korean icebreaker R/V Araon. The surface water concentrations of DMS varied from <1 to 400nM. The highest DMS (up to 300nM) were observed in sea ice-polynya transition zones and near the Getz ice shelf, where both the first local ice melting and high plankton productivity were observed. In other regions, high DMS concentration was generally accompanied by higher chlorophyll and ΔO2/Ar. The large spatial variability of DMS and primary productivity in the surface water of the Amundsen Sea seems to be attributed to melting conditions of sea ice, relative dominance of Phaeocystis Antarctica as a DMS producer, and timing differences between bloom and subsequent DMS productions. The depth profiles of DMS and ΔO2/Ar were consistent with the horizontal surface data, showing noticeable spatial variability. However, despite the large spatial variability, in contrast to the previous results from 2009, DMS concentrations and ΔO2/Ar in the surface water were indistinct between the two major domains: the sea ice zone and polynya region. The discrepancy may be associated with inter-annual variations of phytoplankton assemblages superimposed on differences in sea-ice conditions, blooming period, and spatial coverage along the vast surface area of the Amundsen Sea.

Electrochemical conversion characteristics of ammonia to nitrogen.

In order to evaluate the electrolytic decomposition characteristics of ammonia to nitrogen, this work has studied several experimental variables of electrolytic ammonia decomposition. The effects of the pH and the chloride ion in the solution, kinds of anodes such as IrO(2,) RuO(2), and Pt on the electrolytic decomposition of ammonia were compared, and the existence of a membrane equipped in the cell, the changes of the current density, the initial ammonia concentration, and so on were investigated for the decomposition. The performances of the electrode were totally in the order of RuO(2) approximately IrO(2) > Pt in both the acid and alkali conditions. The ammonia decomposition was the highest at a current density of 80 mA/cm(2), over which it decreased, because the adsorption of the ammonia at the electrode surface was hindered by the hydroxyl ions in the solution. The ammonia decomposition yield increased with the concentration of the chloride ion in the solution. However, the increment rate became much lesser over 10 g/l of the chloride ion. The RuO(2) electrode among the tested anodes generated the most OH radicals which could oxidize the ammonium ion at pH 7.