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While microplastic analysis in aquatic systems is rather well standardized, the determination of microplastics in terrestrial samples has been less explored. Here, we review methods for microplastic analysis, with focus on sampling location and design, soil quantity, sampling depth and equipment, and sample handling and preservation. We found that the random sampling design can be used to collect a representative sample. Stainless steel shovels or soil augers were the most common tools for collecting topsoil, from 0 to 30 cm. Deep soil samples, of more than 100 cm depth, can only be obtained using a core drill. The number of soil samples collected in the field depends on the available budget and instruments for microplastic analysis. For example, if a micro-Fourier transform infrared microscope is used for analysis, soil samples as small as 15.0 g per point can be collected. Once the soils are collected, they can be stored in non-plastic containers, e.g., aluminum bags, to reduce contamination. [ABSTRACT FROM AUTHOR]

Recently, global urbanization and industrialization have resulted in excessive groundwater exploitation, and the occurrence and damage of land subsidence to human life and property are increasing accordingly. The present study assessed the impact of tunnel excavation on the groundwater system and potential land subsidence in a Korean metropolitan area. A numerical model was established to predict groundwater level variations with tunnel excavation, and the mechanisms and cases of land subsidence worldwide were reviewed. The established model adequately represented the groundwater system in the study area. The tunnel excavation decreased the groundwater level along the tunnel line, and significant groundwater drawdown primarily occurred up to 6.1 m at locations with high permeability, leading to the temporary development of a large depression cone. The study area has favorable conditions for land subsidence, and curved tunnel excavation may induce ground disturbance, resulting in groundwater inflow and soil loss in the region. In addition, the risk of land subsidence is expected to persist owing to the lag time caused by the creep phenomenon, even though the groundwater level recovers. Efforts to effectively reduce land subsidence damage in urban areas are crucial, requiring measures such as controlling land subsidence occurrence and implementing prevention measures through early recognition, including artificial recharge of groundwater, underground cavity observation with ground penetrating radar, land subsidence observation with a borehole extensometer, and groundwater level monitoring systems. [ABSTRACT FROM AUTHOR]

Land subsidence is the gradual or sudden dropping of the ground surface developed by increasing the total stress. Most studies have discussed the relationship between land subsidence with groundwater level. However, there is a lack of discussion on groundwater environmental changes after occurring land subsidence. This study aimed to evaluate the hydrogeological and water chemistry characteristics of construction sites with land subsidence. Land subsidence in the Yangyang coastal area occurred suddenly on August 3, 2022, when the retaining wall of the construction collapsed. The groundwater level was measured three times, and water samples were collected twice between August 5, 2022, and September 5, 2022, for laboratory analysis. After land subsidence occurred, the average groundwater level was − 19.91 m ground level (GL) on August 9, 2022, and finally decreased to − 19.21 m GL on September 05, 2022. The groundwater levels surrounding the construction site gradually increased for a month. The electrical conductivity value measured at the monitoring wells ranged from 89 to 7800 μS/cm, and four wells exceeded the measurement limit near the groundwater leaked points. The highest mixing ratio of leaked water samples, collected on August 9, 2022, was 27.6%. Furthermore, the fresh groundwater-saltwater interface depth was estimated to be above the construction bottom. Although groundwater levels recovered, the groundwater quality continuously is affected by saltwater. This finding could contribute to understanding the hydrogeological characteristics surrounding construction sites with land subsidence and provide insight into the hydrochemical evolution process during declined groundwater levels in coastal aquifers. [ABSTRACT FROM AUTHOR]

MoS2 has attracted intense interest in many applications. Natural MoS2 and field-effect transistors made of it generally exhibit n-type characteristics, but its origin is unknown. Herein, we show that C is the origin of the universal n-type doping of natural MoS2. Photoemission spectroscopies reveal that while many MoS2 samples with C detected are n-type, some without C exhibit p-type characteristics. The C-free, p-type MoS2 changes to n-type over time with the concurrent appearance of C that is out-diffused from bulk, indicating that C induces the n-type doping. The C-origin is verified by C-deposition and supported by theoretical calculations. This carbon appears as nanometer-scale defects frequently observed in scanning tunneling microscopy. In addition, we propose, based on the calculations, that S vacancies are responsible for the p-type characteristics, which contrasts with the widespread belief. This work provides new perspectives on MoS2 doping and presents a new direction for fabricating reliable MoS2 devices. [ABSTRACT FROM AUTHOR]

The sole situation of semi-crystalline structure induced single performance remarkably limits the green cryogels in the application of soft devices due to uncontrolled freezing field. Here, a facile strategy for achieving multifunctionality of cryogels is proposed using total amorphization of polymer. Through precisely lowering the freezing point of precursor solutions with an antifreezing salt, the suppressed growth of ice is achieved, creating an unusually weak and homogenous aggregation of polymer chains upon freezing, thereby realizing the tunable amorphization of polymer and the coexistence of free and hydrogen bonding hydroxyl groups. Such multi-scale microstructures trigger the integrated properties of tissue-like ultrasoftness (Young's modulus <10 kPa) yet stretchability, high transparency (~92%), self-adhesion, and instantaneous self-healing (<0.3 s) for cryogels, along with superior ionic-conductivity, antifreezing (−58 °C) and water-retention abilities, pushing the development of skin-like cryogel electronics. These concepts open an attractive branch for cryogels that adopt regulated crystallization behavior for on-demand functionalities. Green cryogels are highly desirable for soft devices but often formed as crystalline-crosslinked networks due to lack of control of the freezing process. Here, the authors demonstrate a strategy to obtain multifunctional cryogels by total amorphization of the polymer using anti-freeze salts to lower the freezing point of the precursor solution. [ABSTRACT FROM AUTHOR]

We previously found that methylmercury induces expression of oncostatin M (OSM), which is released extracellularly and binds to tumor necrosis factor receptor 3 (TNFR3), possibly enhancing its own toxicity. However, the mechanism by which methylmercury causes OSM to bind to TNFR3 rather than to its known receptors, OSM receptor and LIFR, is unknown. In this study, we aimed to elucidate the effect of methylmercury modification of cysteine residues in OSM on binding to TNFR3. Immunostaining of TNFR3-V5-expressing cells suggested that methylmercury promoted binding of OSM to TNFR3 on the cell membrane. In an in vitro binding assay, OSM directly bound to the extracellular domain of TNFR3, and this binding was promoted by methylmercury. Additionally, the formation of a disulfide bond in the OSM molecule was essential for the binding of both proteins, and LC/MS analysis revealed that methylmercury directly modified the 105th cysteine residue (Cys105) in OSM. Next, mutant OSM, in which Cys105 was replaced by serine or methionine, increased the binding to TNFR3, and a similar effect was observed in immunoprecipitation using cultured cells. Furthermore, cell proliferation was inhibited by treatment with Cys105 mutant OSMs compared with wildtype OSM, and this effect was cancelled by TNFR3 knockdown. In conclusion, we revealed a novel mechanism of methylmercury toxicity, in which methylmercury directly modifies Cys105 in OSM, thereby inhibiting cell proliferation via promoting binding to TNFR3. This indicates a chemical disruption in the interaction between the ligand and the receptor is a part of methylmercury toxicity. [ABSTRACT FROM AUTHOR]

Soil microplastic (MP) contamination through plastic mulch and greenhouse soils is a global concern. However, whether plastic mulch contaminates the soil to a greater or lesser extent than the contamination caused by building greenhouses with MPs has not been documented. This study is the first to examine and compare the abundance and distribution of MPs in greenhouses and mulched soils of Korean agriculture field to obtain the polymer types and sizes of MPs present. The MP abundances in the greenhouse and mulched soils ranged from 50 to 379 and 158 to 943 particles kg− 1, respectively, with an average abundance of 221.4 and 356.8 particles kg− 1. No significant differences (p > 0.05) were observed in soil MP contamination between the greenhouse and mulching sites. At both sites, fragments (91%) were the predominant MP shape. MPs with a size < 300 μm were dominant, covering 99.57% of the mulch site and 99.69% of the greenhouse. Six MP polymers in the greenhouse and mulching sites: polypropylene, polyethylene, polyethylene terephthalate, polyvinyl chloride, polyethylene amide, and polymethyl methacrylate were identified. The soil MP contaminants in greenhouses and mulch sites in the Haean Basin have originated from the use of plastic films, and ropes. The first-hand data established by this study showed the same degree of MP contamination in mulch and greenhouse soils, which provides important background information on MP characteristics to understand the environmental behavior and ecological effects of MPs in soil systematically and comprehensively. [ABSTRACT FROM AUTHOR]

Engineering excitation wavelength of photosensitizers (PSs) for enhanced reactive oxygen species (ROS) generation has inspired new windows for opportunities, enabling investigation of previously impracticable biomedical and photocatalytic applications. However, controlling the wavelength corresponding to operating conditions remains challenging while maintaining high ROS generation. To address this challenge, we implement a wavelength-engineerable imidazolium-based porous organic photocatalytic ROS generation system (KUP system) via a cost-effective one-pot reaction. Remarkably, the optimal wavelength for maximum performance can be tuned by modifying the linker, generating ROS despite the absence of metal ions and covalently attached heavy atoms. We demonstrate that protonated polymerization exclusively enables photosensitization and closely interacts with oxygen related to the efficiency of photosensitizing. Furthermore, superior tumor eradication and biocompatibility of the KUP system were confirmed through bioassays. Overall, the results document an unprecedented polymerization method capable of engineering wavelength, providing a potential basis for designing nanoscale photosensitizers in various ROS-utilizing applications. Engineering excitation wavelength of photosensitizers allows to enhanced reactive oxygen species but controlling the wavelength corresponding to operating conditions remains challenging. Here, the authors implement a wavelength-engineerable imidazolium-based porous organic polymer and demonstrate tuning of the optimal wavelength for maximum performance by modifying the linker system. [ABSTRACT FROM AUTHOR]

Targeting the signaling pathway of the Vascular endothelial growth factor receptor-2 is a promising approach that has drawn attention in the quest to develop novel anti-cancer drugs and cardiovascular disease treatments. We construct a screening pipeline using machine learning classification integrated with similarity checks of approved drugs to find new inhibitors. The statistical metrics reveal that the random forest approach has slightly better performance. By further similarity screening against several approved drugs, two candidates are selected. Analysis of absorption, distribution, metabolism, excretion, and toxicity, along with molecular docking and dynamics are performed for the two candidates with regorafenib as a reference. The binding energies of molecule1, molecule2, and regorafenib are − 89.1, − 95.3, and − 87.4 (kJ/mol), respectively which suggest candidate compounds have strong binding to the target. Meanwhile, the median lethal dose and maximum tolerated dose for regorafenib, molecule1, and molecule2 are predicted to be 800, 1600, and 393 mg/kg, and 0.257, 0.527, and 0.428 log mg/kg/day, respectively. Also, the inhibitory activity of these compounds is predicted to be 7.23 and 7.31, which is comparable with the activity of pazopanib and sorafenib drugs. In light of these findings, the two compounds could be further investigated as potential candidates for anti-angiogenesis therapy. [ABSTRACT FROM AUTHOR]

Purpose: Soil is a thin coating of matter that covers the earth's surface, formed through the process of rock weathering. It is a natural filter for impurities in groundwater and is very important to human health. Recently, some studies from around the world have confirmed that the presence of microplastics in soil is increasing. However, most of these studies only examined the impacts of soil microplastic contamination one or two soil health indicators, rather than study all three soil health indicators at once. Methods: In this review, we selected papers published internationally in the past decade and examined the trend of the effects of soil microplastic contamination on all three soil health indicators. Results and discussion: Soil microplastic contamination resulted in either an increase or decrease in the trend of the effects on physicochemical and biological soil properties. In other cases, microplastic contaminants do not affect soil properties. The alteration of soil health properties by microplastics was associated with a couple of reasons such as microplastic concentrations and types, changes in soil mechanics and microorganisms. Conclusions: The current impact and severity of soil microplastic contamination on soil health properties are expected to persist for a long time, especially with increasing global plastic production. Therefore, more research is required to continuously assess the impact of microplastic contamination on other indicators of soil health that has not been studied previously. [ABSTRACT FROM AUTHOR]

In the Republic of Korea, Haean basin is the largest agricultural area in Soyang watershed which is drinking water source for more than 20 million people residing in Seoul metropolis. It is important to investigate any factor affecting the stream or groundwater quality, especially nitrate () concentration in Haean basin which can affect drinking water quality of Soyang watershed. For this purpose, multiple environmental tracers were studied, including major ions and stable isotopes of water (δ2H and δ18O). Stream and groundwater samples were collected from six predominant agricultural land uses located at different elevation points in the study area. Fields with high fertilizer amounts at intermediate to low elevation using flood irrigation method, had contaminated water. Mixing model of chloride (Cl−) and δ18O indicated groundwater recharge from precipitation and lateral inflow from fields at intermediate to low elevation, regarding solute inputs. Another mixing model and δ18O defined the existence of lateral inflow of agricultural water in fields at low elevation. The highest water contamination was found in ginseng fields located at high, intermediate, and low elevation, for (68.79 mg/L), exceeding the World Health Organization standard of 50 mg/L in groundwater. This explains that anthropogenic agricultural practices (high fertilizer amounts and flood irrigation) through precipitation and lateral inflow of agricultural water recharge processes, are the major source of groundwater contamination in Haean basin. After anthropogenic inputs, elevation complexity has played a role in spatial heterogeneity of in stream and groundwater. Findings of this study presents a need to focus on ginseng fields and their agricultural practices to maintain stream and groundwater quality of nearby aquifer. [ABSTRACT FROM AUTHOR]

Geothermal wells with depths of 4.3 and 4.1 km were drilled into an enhanced geothermal system (EGS) in Pohang, Republic of Korea. After five times of hydraulic fracturing, the groundwater level of the geothermal wells decreased after a Mw 5.5 earthquake in Pohang. The objective of this study was to monitor the groundwater level and temperature and determine the hydrogeological and hydrochemistry of two geothermal wells (PX-1 and PX-2) and one monitoring well (EXP-1) at the EGS site. The hydrochemical data of the EGS wells was also compared with the groundwater characteristics of eight wells at the National Groundwater Monitoring Station (NGMS). First, groundwater samples were collected from a depth of approximately 700 m, and an automatic water level recorder was used to monitor changes in the groundwater level and temperature for two years at the EGS site. Second, groundwater level and temperature data in the NGMS wells were collected from the National Groundwater Information Center's website and annual report on groundwater monitoring for comparisons with the EGS site. The results showed that the rate of groundwater increase was in the order PX-2, PX-1, and EXP-1, and the temperature decrease was the fastest in PX-1 and similar between PX-2 and EXP-1. The eight wells in the NGMS showed only temporary changes. The groundwater in the EGS is the Na-Cl type, but that in the NGMS is a mixture of the Ca-HCO3 and Na-HCO3 type. The EGS site has not yet recovered from the earthquake. [ABSTRACT FROM AUTHOR]

There is growing evidence that the global meteorological cycle, on which most countries depend for water security, is deviating from traditional patterns due to climate change. The global response to this has been to adopt more integrated water resource management (IWRM) and adaptive management (AM) approaches, but the question of 'how' remains largely unanswered. This is because 'one size fits all' no longer applies, as IWRM and AM denote flexible, situation-tailored, and area-specific management systems. Understanding how water policy in a region or country has historically evolved and sometimes failed, offers a good starting point to shed light on the next step or 'how next'; however, this aspect remains underexplored. This study focuses on South Korea, one of the medium-high water stress countries affected by climate change. For a structural and theoretical analysis, the Hall's theory of paradigmatic policy change was applied, which revealed that South Korea is currently in the 'contestation' stage following the 'fragmented authority' stage due to failures in the 'policy experiment' stage. The analysis identified continued administrative rigidity and a construction-centric culture as the main causes of the failure of transition attempts made during 1994–2013. Hence, to answer the 'how next' question, this study proposes that the IWRM and AM be institutionalised in South Korea through the educational system at all levels, by enhancing the learning process and cultural adoption. Without garnering general support, the structural reforms of 2018–2020 can be overturned easily if the next government endorses traditional values. [ABSTRACT FROM AUTHOR]

Plastic particles of less than 5 mm size, referred as microplastics, have recently become a major environmental issue. While microplastics are well known in marine and lake systems, there have been less investigations in soils and groundwater. Here we review the origin, shape, impact, and mitigation strategies of soil and groundwater microplastics. We found that littering is the main origin of microplastics in global topsoils, while greenhouses are the main source of microplastics in South Korea. Fibers and pellets are dominant microplastic shapes in soil and groundwater. Microplastic contamination of soil and groundwater is detrimental to human health, plants, nematodes, earthworms, and soil properties. Remediation methods include pyrolysis, replacing plastics by biodegradable plastics, plastic filtration, and subsequent chemical or biological degradation. [ABSTRACT FROM AUTHOR]

We report unique observations from drilling and hydraulic stimulation at a depth of approximately 4.3 km in two Enhanced Geothermal System (EGS) wells at the Pohang EGS site, South Korea. We surveyed drilling logs and hydraulic stimulation data, simulated pore pressure diffusion around the fault delineated by seismic and drilling log analyses, conducted acoustic image logging through the EGS wells, observed significant water level drops (740 m) in one of the two EGS wells, and obtained hydrochemical and isotopic variation data in conjunction with the microbial community characteristics of the two EGS wells. We discuss the hydraulic and hydrochemical responses of formation pore water to a few key seismic events near the hypocenter. We focused on how the geochemistry of water that flowed back from the geothermal wells changed in association with key seismic events. These were (1) a swarm of small earthquakes that occurred when a significant circulation mud loss occurred during well drilling, (2) the MW 3.2 earthquake during hydraulic stimulation, and (3) the MW 5.5 main shock two months after the end of hydraulic stimulation. This study highlights the value of real-time monitoring and water chemistry analysis, in addition to seismic monitoring during EGS operation. [ABSTRACT FROM AUTHOR]

Despite standardization efforts, vendors still use specific proprietary software algorithms for echocardiographic strain measurements, which result in high inter-vendor variability. Using vendor-independent software could be one solution. Little is known, however, how vendor specific image characteristics can influence tracking results of such software. We therefore investigated the reproducibility, accuracy, and scar detection ability of strain measurements on images from different vendors by using a vendor-independent software. A vendor-independent software (TomTec Image Arena) was used to analyse datasets of 63 patients which were obtained on machines from four different ultrasound machine vendors (GE, Philips, Siemens, Toshiba). We measured the tracking feasibility, inter-vendor bias, the relative test-re-test variability and scar discrimination ability of strain measurements. Cardiac magnetic resonance delayed enhancement images were used as the reference standard of scar definition. Tracking feasibility on vendor datasets were significantly different (p < 0.001). Variability of global longitudinal strain (GLS) measurements was similar among the vendors whereas variability of segmental longitudinal strain (SLS) showed modest difference. Relative test-re-test variability of GLS and SLS showed no relevant differences. No significant difference in scar detection capability was observed. Average GLS and SLS values were similar among vendors. Reproducibility of GLS measurements showed no difference among vendors and was in acceptable range. SLS reproducibility was high but similar for all vendors. No relevant difference was found for identifying regional dysfunction. Tracking feasibility showed a substantial difference among images from different vendors. Our findings demonstrate that tracking results depend mainly on the software used and show little influence from vendor specific image characteristics. [ABSTRACT FROM AUTHOR]

Methylmercury is an environmental pollutant that causes neurotoxicity. Recent studies have reported that the ubiquitin-proteasome system is involved in defense against methylmercury toxicity through the degradation of proteins synthesizing the pyruvate. Mitochondrial accumulation of pyruvate can enhance methylmercury toxicity. In addition, methylmercury exposure induces several immune-related chemokines, specifically in the brain, and may cause neurotoxicity. This summary highlights several molecular mechanisms of methylmercury-induced neurotoxicity. [ABSTRACT FROM AUTHOR]

Background: To evaluate the facial asymmetry, three-dimensional computed tomography (3D-CT) has been used widely. This study proposed a method to quantify facial asymmetry based on 3D-CT. Methods: The normal standard group consisted of twenty-five male subjects who had a balanced face and normal occlusion. Five anatomical landmarks were selected as reference points and ten anatomical landmarks were selected as measurement points to evaluate facial asymmetry. The formula of facial asymmetry index was designed by using the distances between the landmarks. The index value on a specific landmark indicated zero when the landmarks were located on the three-dimensional symmetric position. As the asymmetry of landmarks increased, the value of facial asymmetry index increased. For ten anatomical landmarks, the mean value of facial asymmetry index on each landmark was obtained in the normal standard group. Facial asymmetry index was applied to the patients who had undergone orthognathic surgery. Preoperative facial asymmetry and postoperative improvement were evaluated. Results: The reference facial asymmetry index on each landmark in the normal standard group was from 1.77 to 3.38. A polygonal chart was drawn to visualize the degree of asymmetry. In three patients who had undergone orthognathic surgery, it was checked that the method of facial asymmetry index showed the preoperative facial asymmetry and the postoperative improvement well. Conclusions: The current new facial asymmetry index could efficiently quantify the degree of facial asymmetry from 3D-CT. This method could be used as an evaluation standard for facial asymmetry analysis. [ABSTRACT FROM AUTHOR]

This study was conducted to determine the optimal entomopathogenic fungus for the simultaneous control of the adults of two mosquito species, Aedes albopictus and Culex pipiens. The pathogenicity and virulence against the two species of mosquitoes were evaluated by using 30 isolates of Beauveria bassiana, an entomopathogenic fungus isolated from Korea that has high thermotolerance and UV-B tolerance. Regarding pathogenicity, 23 isolates were pathogenic to Ae. albopictus and 12 isolates were pathogenic to Cx. pipiens; Ae. albopictus adults were more susceptible to B. bassiana than Cx. pipiens adults. Among the isolates, 6 isolates that were simultaneously pathogenic to the two species of mosquitoes were used to evaluate virulence and conidia productivity. B. bassiana CN6T1W2 and JN5R1W1 had higher virulence than the other isolates, and they were more virulent in Ae. albopictus than inCx. pipiens. The conidia productivity of B. bassiana JN5R1W1 on millet grain medium was higher than that of B. bassiana CN6T1W2. Based on these results, B. bassiana JN5R1W1 was selected as the most efficient isolate for the simultaneous control of the two mosquito species. B. bassiana JN5R1W1 can be used effectively in the development of fungal insecticides to simultaneously control Ae. albopictus and Cx. pipiens adults with similar distribution areas. [ABSTRACT FROM AUTHOR]

Porphyromonas gingivalis induces destruction of periodontal tissues that surround and support the teeth, contributing to the development of periodontitis, which eventually results in tooth loss in adults. A 53-kDa protein of P. gingivalis is a major subunit variant protein of minor fimbriae (Mfa1), and is reported to be highly immunogenic and considered as a potential vaccine candidate. The gene encoding 53-kDa protein, was divided into three segments, and each DNA segment was fused to the gene coding for cholera toxin B subunit (CTB) to improve gut mucosal immune responses. The ctb-mfal fusion genes were expressed in the leaf tissues of Nicotiana benthamiana using agroinfiltration. Immunoblot analysis revealed that CTB-Mfa1 fusion proteins were produced in the agroinfiltrated leaves. The interaction of the plant-produced CTB-Mfa1 fusion proteins with GM1-ganglioside, which acts as the binding site for native CTB, was confirmed by GM1-ELISA. Mice immunized orally with the agroinfiltrated leaf powder containing the CTB-Mfa1 fusion proteins elicited serum IgG and fecal IgA antibodies to CTB and Mfa1. These results suggest that CTB-Mfa1 fusion proteins produced in plants can be used as an oral vaccine to control P. gingivalis infection-associated periodontitis. [ABSTRACT FROM AUTHOR]

An amendment to this paper has been published and can be accessed via a link at the top of the paper. [ABSTRACT FROM AUTHOR]

Due to the complex profile of atherosclerotic risk factors, an integrated analysis of a specific individual is difficult. Endothelial function reflects a composite of various risk factors, and may be used as an optimal tool to estimate the overall atherosclerotic risk. In this study, we investigated the value of digital Reactive Hyperemia Index (RHI) in an actual population with multiple atherosclerotic risk factors or coronary artery disease (CAD). A total of 417 patients from the Seoul National University Boramae Medical Center RHI registry were enrolled in this study. Patients were enrolled from January, 2013 to July, 2016. RHI was measured using the EndoPAT2000 system (Itamiar Medical Inc. Israel). The mean value of RHI was 1.67 ± 0.48 in total study population. Among various atherosclerotic risk factors, RHI was significantly lower in older (> 60 years) patients, diabetics, smokers’ patients on statin therapy, and those with coronary or cerebrovascular disease. Most of these findings were consistent after adjustment with multiple regression analysis. RHI was significantly associated with CAD, with a hazard ratio of 1.80 (95% confidence interval 1.15-2.80, p = 0.010). In the subgroup with CAD, current smoking was the only finding showing a lower RHI. Brachial-ankle pulse wave velocity, which is a surrogate marker of arterial atherosclerotic change, was not correlated with RHI in patients with clinically significant atherosclerotic disease. RHI was significantly reduced by major atherosclerotic risk factors and in clinical atherosclerotic disease. RHI may reflect a composite effect of risk factors pertaining to the endothelial function. [ABSTRACT FROM AUTHOR]

We report a new series of low band gap (LBG) polymers (P1-P4), in which para or meta- alkoxyphenylthiophene (APTh) substituted benzodithiophene and 2,5-ethylhexyl-3,6-bis(5-bromothiophen-2-yl)pyrrolo[3,4-c]-pyrrole-1,4-dione or 2-ethylhexyl-4,6-dibromo-3-fluorothieno[3,4-b]thiophene-2-carboxylate are key repeating units. All the polymers showed broad absorption profiles over 900 nm with reduced optical band gaps (Egopt). Interestingly, the straightforward modification (exchanging the topology of alkoxy side chain on phenyl group of APTh in donor unit) brought considerable changes in photophysical and photovoltaic properties of new polymers. In particular, meta-substituted polymers (P2, P4) showed reduced Egopt (1.26, 1.41 eV), deep highest occupied molecular orbitals (HOMOs) (-5.23, -5.28 eV) than para-substituted polymers P1, P3 (Egopt=1.33, 1.44 eV; HOMOs=-5.19, -5.20 eV). Furthermore, the optimized P2 and P4 based devices delivered an enhanced power conversion efficiency (PCE) of 4.39 and 4.33%, with open-circuit voltage (Voc) of 0.71 and 0.79 V, respectively, which are higher than P1 (PCE of 2.95 with Voc of 0.65) and P3 (PCE of 2.33% with Voc of 0.69 V) based devices. [ABSTRACT FROM AUTHOR]

We present a review of groundwater studies over the past 50 years (1968-2017) in Korea. With economic and agricultural growth, water demand has been expanding, and groundwater development is gradually increasing. Initially, groundwater studies were largely focused on using pumping and slug tests to understand aquifers in Korea. However, the interest has expanded to groundwater monitoring and data analyses, as many national and local networks for monitoring groundwater quantity and quality have been implemented. Frequent severe droughts in recent decades have led to research on the design and pilot tests for managed aquifer recharge, especially on the volcanic island of Jeju and agricultural areas. As groundwater development and its use has increased, groundwater contamination is becoming a public grievance. Thus, effective investigation of contaminated groundwater and its efficient remediation are big issues in the Research and Development (R & D) sector. The recent Gyeongju earthquake posed an additional challenge for Korean groundwater scientists to develop a method to predict earthquakes using groundwater monitoring. Furthermore, changes in precipitation patterns caused by the changing climate aggravate groundwater recharge conditions. The country has seen many academic and technical achievements in groundwater science, but many issues remain to be resolved in the near future. [ABSTRACT FROM AUTHOR]

Periodontitis is a bacterial infection-induced inflammatory disease that affects the tissues surrounding the teeth and is the main cause of tooth loss in adults. Porphyromonas gingivalis, a black-pigmented gram-negative anaerobe, is a major causative agent of periodontitis. A 53-kDa protein of the bacterium has been demonstrated to be highly immunogenic and recognized by sera from most periodontitis patients, and it is now considered as a potential target of protective immunity. In this study, complementary DNA encoding monoclonal antibodies to 53-kDa protein of P. gingivalis A7A1-28 was cloned from hybridoma cell lines expressing the antibodies. The heavy and light chain genes were constructed into plant expression vectors under the control of the rice α-amylase 3D (RAmy3D) promoter. The recombinant plant expression vectors were introduced into rice cells ( Oryza sativa L. cv. Dongjin) using particle bombardment transformation method. Transgenic rice calli were selected by genomic DNA PCR and used to establish cell suspension cultures. The expression of the heavy and light chain genes of the monoclonal antibodies in the rice cell suspension cultures was detected by western blot analysis. The plant-produced monoclonal antibodies showed specific reactivity with 53-kDa proteins of P. gingivalis. These results suggest that 53-kDa protein-specific monoclonal antibodies produced in the rice cell suspension cultures are biologically active against the bacterial protein and can be used for passive immunization to prevent P. gingivalis-induced periodontal disease. [ABSTRACT FROM AUTHOR]

Soil temperatures, water temperatures, and weather parameters were monitored at a variety of locations in the vicinity of King Sejong station, King George Island, Antarctica, during summer 2010-2011. Thermal characteristics of soil and water were analysed using time-series analyses, apparent thermal diffusivity (ATD), and active layer thickness. The temperatures of pond water and nearby seawater showed the distinctive diurnal variations and correlated strongly with solar radiation (r = 0.411-0.797). Soil temperature (0.1-0.3 m depth) also showed diurnal fluctuations that decreased with depth and were directly linked to air temperature (r = 0.513-0.783) rather than to solar radiation; correlation decreased with depth and the time lag in the response increased by 2-3 hours per 0.1 m of soil depth. Owing to the lack of snow cover, summertime soil temperature was not decoupled from air temperature. Estimated ATD was between 0.022 and 29.209 mm2/sec, showed temporal and spatial variations, and correlated strongly with soil moisture content. The maximum estimated active layer thickness in the study area was a 41-70 cm, which is consistent with values reported in the previous work. [ABSTRACT FROM AUTHOR]

The success of endodontic treatment depends on the eradication of microorganisms from the root canal system and the prevention of reinfection. The purpose of this investigation was to evaluate the antibacterial and antibiofilm efficacy of N-acetylcysteine (NAC), an antioxidant mucolytic agent, as an intracanal medicament against selected endodontic pathogens. Minimum inhibitory concentrations (MICs) of NAC for Actinomyces naeslundii, Lactobacillus salivarius, Streptococcus mutans, and Enterococcus faecalis were determined using the broth microdilution method. NAC showed antibacterial activity, with MIC values of 0.78-1.56 mg/ml. The effect of NAC on biofilm formation of each bacterium and a multispecies culture consisting of the four bacterial species was assessed by crystal violet staining. NAC significantly inhibited biofilm formation by all the monospecies and multispecies bacteria at minimum concentrations of 0.78-3.13 mg/ml. The efficacy of NAC for biofilm disruption was evaluated by scanning electron microscopy and ATP-bioluminescence quantification using mature multispecies biofilms. Preformed mature multispecies biofilms on saliva-coated hydroxyapatite disks were disrupted within 10 min by treatment with NAC at concentrations of 25 mg/ml or higher. After 24 h of treatment, the viability of mature biofilms was reduced by > 99% compared with the control. Moreover, the biofilm disrupting activity of NAC was significantly higher than that of saturated calcium hydroxide or 2% chlorhexidine solution. Within the limitations of this in vitro study, we conclude that NAC has excellent antibacterial and antibiofilm efficacy against endodontic pathogens and may be used as an alternative intracanal medicament in root canal therapies. [ABSTRACT FROM AUTHOR]

We present an overview of the current status of unconventional energy development, particularly of shale gas, and underground CO storage as a measure to mitigate greenhouse gas increase in the atmosphere. We review their potential to induce seismicity, which has caused debates among related energy enterprises, engineers, researchers, and environmental and public communities regarding their potential hazards. Studies show that fracking can be a problem in that it consumes abundant water, but the seismicity induced by fracking has not yet been observed to induce many felt earthquakes. However, massive wastewater injection, a part of the unconventional energy development process has caused M5.0+ earthquakes in the past as well as several recent and ongoing cases of induced seismicity. Large-scale CO injection as a part of carbon sequestration efforts in the near future has a high risk of inducing large earthquakes. Therefore, injection operations related to both unconventional energy development and carbon sequestration should be optimized and managed to mitigate the likelihood of an induced seismic event. [ABSTRACT FROM AUTHOR]

This study was performed to examine the chemical and isotopic compositions of groundwater used in open loop GHP systems and natural groundwater around the open loop GHP systems and to evaluate the influence of open loop GHP systems' operation on groundwater chemistry in Korea. The water temperature of groundwater used in open loop GHP systems ranged from 6.0 to 37.1°C and decreased by 6.7 to 11.6°C compared with that of natural groundwater around the open loop GHP systems. The pH, EC, Eh, Fe, and Mn of the groundwater were not significantly affected by open loop GHP systems' operation. The groundwaters used in open loop GHP systems showed various water types, such as Ca-HCO, Ca-Cl, Ca-SO, and Na-HCO· Although HCO and Cl concentrations were slightly influenced by open loop GHP systems at some sites, the groundwater chemistry used in the open loop GHP systems did not significantly change at most sites. In addition, carbonate and silica minerals and minerals containing Mn were in undersaturated condition, which indicates that the precipitation of these minerals will not occur. However, some minerals containing Fe, such as Fe(OH), goethite, and hematite can be precipitated as scale within these system. In the open loop GHP systems selected in this study, the influence of open loop GHP systems on groundwater chemistry is not revealed sufficiently because of short-term monitoring of groundwater chemistry. However, integrated long-term monitoring is necessary to evaluate influence of open loop GHP systems on groundwater chemistry and to improve our understanding of the environmental impacts related to these systems. [ABSTRACT FROM AUTHOR]

We examined groundwater and stream water interaction in the Inbuk stream, Korea, using various approaches including hydrologic, thermal, hydrochemical, and isotopic methods. For this purpose, we installed four piezometers (IYHW1-4) in the streambed at 10 m interval across the stream and at depths of 0.90 to 1.54 m. We monitored water levels and water temperatures every hour using automatic transducers at the piezometers and in the stream (IYSW1) from September 2013 to April 2014. We also analyzed chemical and isotopic compositions for the hyporheic waters, stream water, and nearby groundwater in early September and late November in 2013. The water levels and hydraulic gradients revealed that three (IYHW1, 2, and 4) of the piezometers were in upwelling conditions for most of the monitoring period, except for the earliest short period (considered to be the wet season), whereas one piezometer (IYHW3) showed a reverse behavior, indicating that the gaining was dominant in the dry period. The mean calculated influx to the stream was 3.04 × 10 cm/sec. Observed temperatures of stream water, hyporheic waters, and groundwater also revealed that stream water was downwelling in the early monitoring period (wet season), whereas the groundwater was generally upwelling in most of the resting period, which is consistent with the water level interpretation. Chemical composition analysis indicated that most of the waters were Ca-HCO type for both seasons. However, no distinctive difference between chemical compositions of water without substantial seasonal variation negated any inference on the flow conditions. The mixing ratios computed from oxygen and hydrogen isotopic compositions indicated that losing conditions were dominant in the wet season, whereas gaining conditions prevailed in the dry season. The interpretations of stream water and groundwater interactions based on these different methods are relatively consistent for this study area, indicating that such combined methods will be very useful in enhancing understanding of groundwater and stream water interaction. [ABSTRACT FROM AUTHOR]

N-acetyl cysteine (NAC) is an antioxidant that possesses anti-inflammatory activities in tissues. In the field of dentistry, NAC was demonstrated to prevent the expression of LPS-induced inflammatory mediators in phagocytic cells and gingival fibroblasts during the inflammatory process, but the effect of NAC on oral pathogens has been rarely studied. Here, we examined the effect of NAC against planktonic and biofilm cells of Prevotella intermedia, a major oral pathogen. NAC showed antibacterial activity against the planktonic P. intermedia with MIC value of 3 mg/ml and significantly decreased biofilm formation by the bacterium even at sub MIC. NAC did not affect the antibiotic susceptibility of planktonic P. intermedia, showing indifference (fractional inhibitory concentration index of 0.5-4) results against the bacterium in combination with ampicillin, ciprofloxacin, tetracycline or metronidazole. On the other hand, viability of the pre-established bacterial biofilm exposed to the antibiotics except metronidazole was increased in the presence of NAC. Collectively, NAC may be used for prevention of the biofilm formation by P. intermedia rather than eradication of the pre-established bacterial biofilm. Further studies are required to explore antibacterial and anti-biofilm activity of NAC against mixed population of oral bacteria and its modulatory effect on antibiotics used for oral infectious diseases. [ABSTRACT FROM AUTHOR]

Major fimbriae (FimA) of Porphyromonas gingivalis play an important role in the adherence of the bacterium to oral surfaces, making them a target for the development of a vaccine against periodontal disease. In our previous study, monoclonal antibodies to FimA were expressed in tobacco plants using the agroinfiltration method. In this report, for easy purification, monoclonal antibodies to FimA were produced and accumulated in rice callus suspension culture. The accumulated antibodies were purified by protein G-affinity chromatography. The plant-produced monoclonal antibodies inhibited the binding of P. gingivalis to saliva-coated hydroxyapatite beads, as well as the invasion of oral epithelial KB cells due to the bacterium. The antibodies enhanced the intracellular killing of P. gingivalis by polymorphonuclear neutrophils. These results suggest that FimA-specific monoclonal antibodies produced in a rice suspension culture were easily purified and biologically active against P. gingivalis, and thus may be used for passive immunization to prevent P. gingivalis-induced periodontal disease. [ABSTRACT FROM AUTHOR]

This study was conducted to reveal the trends of the air temperature and soil temperature for 51 years (1960-2010) and their relationship in four of Korea's largest metropolitan cities (Seoul, Incheon, Busan and Daejeon). Also, the trends of the air and soil temperatures between the studied metropolitan cities and a rural area (Chupungryong) were compared to examine the effect of urban heat. Among the metropolitan cities, the long-term mean soil temperatures (depth 0.0, 0.5, 1.0, 1.5, 3.0, 5.0 m) were lowest (13.34-14.80 °C) in Seoul and highest (16.24-16.54 °C) in Busan, which is mainly the effect of the latitude. The soil temperature exponentially increased with depth in the three cities except for Busan and was closely related to the air temperature. The soil temperatures responded well to the air temperature change (maximum correlation coefficients 0.88-0.98) but this response was slightly delayed with depth. The air and soil temperatures increased at the rates of 0.24-0.40 and 0.11-0.73 °C/decade, respectively, for the period. The increasing rate of the soil temperature was the largest in Daejeon as 0.39-0.73 °C/decade, which was almost 2-4 times greater than those of the other cities (0.11-0.40 °C/decade), and it rose with depth. The increase of the soil temperature was coincident with the increase of the air temperature, which indicates that the soil temperature was largely affected by the increasing of the air temperature. In contrast, the increase in air temperature in Chupungryong (0.06 °C/decade) was significantly lower than in the metropolitan cities. In addition, the increase of the soil temperature in the rural area (0.13 °C/decade) was also much lower than that in the inland cities (0.20-0.27 °C/decade) while it showed no substantial difference from that in the coastal cities (0.11-0.15 °C/decade). Therefore, it is inferred that the soil temperature of the metropolitan cities increased with the increase of the air temperature due to global warming as well as the anthropogenic urban heat. [ABSTRACT FROM AUTHOR]

With a growing demand for fresh water, mainly due to the rapidly developing economy, their interests focus on securing plentiful groundwater resources for drinking, domestic, agricultural and industrial purposes. In addition, remediation of contaminated groundwater has become another main interest. Hence, many environmental tracers, such as CFCs, Ra, Rn, CH, δO, δD, H, He, δC, δCl, and applied tracers, such as Cl, Br and rhodamine WT, have been widely used in the country for groundwater studies with different purposes. The main purposes include estimations of submarine groundwater discharge pathways and their quantification in coastal regions, especially in Jeju (volcanic island), as well as examinations of groundwater origin and mixing with stream water, groundwater age dating, tracing (apportioning) the contamination sources of chlorinated solvents (e.g., TCE, PCE) in industrial areas, and identification of reservoir (large dam) leakage. This paper reviews the use of environmental and applied tracers in Korean groundwater studies and provides perspectives on their use. [ABSTRACT FROM AUTHOR]

Groundwater-stream water exchange and mixing in a hyporheic zone were examined using the water chemistry data and multivariate statistical analyses. The study area was the Munsan stream of agricultural area in Paju, Korea. Three rounds of water samplings (August, September, and November, 2008) were conducted for five monitoring nests along the stream flow, with each having three different-depth piezometers in the streambed, one surrounding groundwater well and one stream water point. The chemical compositions of hyporheic water were controlled by those of the groundwater and stream water. The factor analysis identified four main factors that explain 67 % of total variance of the water chemistry data and also revealed that the parameters responsible for water quality variances were mainly related to rainfall, anthropogenic activities, and dissolution of carbonate minerals. The cluster analysis produced a few different groups in August (3 groups), September (4 groups), and November (4 groups), respectively, which showed that the water quality parameters of the three water bodies were very different and the hyporheic water showed a different mixing of the stream water and groundwater at each monitoring point. [ABSTRACT FROM AUTHOR]

The reaction of m-xylylenediamine (mXD) with carbon dioxide was examined and its feasibility as a sequestration material of carbon dioxide was discussed. The reaction was monitored by using the FT-IR and gravitational methods, while the crystalline structure of the reaction product was investigated with elemental analysis, powder Xray diffraction, single crystallography, and 13C MAS NMR spectroscopy. Even at ambient temperature, mXD reacted with carbon dioxide of low partial pressure in the atmosphere and produced a 1: 1 molar adduct which appeared as a white crystalline material. The hydrogen bonds that formed between the adduct molecules resulted in the formation of a stable crystal. The sequestration capacity of mXD was very great, ∼280 mg g mXD−1 below 50 °C. An adsorbent prepared by dispersing mXD on silica was capable of capturing carbon dioxide, but it could be regenerated by evacuating at 25 °C. [ABSTRACT FROM AUTHOR]

The chemical and isotopic compositions of groundwater and stream water in the Haean basin, Korea, which have been intensively used for agricultural irrigation, were examined. The field parameters and chemical compositions were typical of relatively uncontaminated waters, except for the agricultural impact. The low EC levels indicated that the waters had not experienced any significant geochemical processes such as water-rock interaction and evaporation. The very similar chemical compositions and ionic ratios were also indicative of fast circulation and good hydraulic connection. The oxygen and hydrogen isotopic compositions of most of the samples in wet and dry seasons showed very similar range which indicated a single source for both waters without any significant geochemical alteration. However, in the wet season, evaporation trends were observed in some groundwaters because of inflow of irrigation return flow from a rice paddy field. The isotopes of both waters were affected by the altitude and amount of precipitation. [ABSTRACT FROM AUTHOR]

The objective of this study was to evaluate groundwater conditions in the four greatest megacities (Seoul, Busan, Daegu, and Incheon) of Korea using 5-year (2006-2010) monitoring data obtained from the Korean National Groundwater Monitoring Stations. With decreasing of groundwater draft, groundwater levels for the 5-year period were not substantially decreasing but they responded differently to outer stress like rainfall according to degree of urbanization or pavement of surrounding areas. However, groundwater and air temperatures were gradually increasing due to the widespread climate change. Coastal groundwaters (Seoul, Busan, and Incheon) have suffered from seawater intrusion, which can be aggravated by sea level rise in the future. Some monitoring stations of the megacities observed a drastic decrease of groundwater level for a specific period and the marked increasing of electrical conductivity; thus, detailed investigations revealing the causes and appropriate mitigation measures are required. Urban groundwater did not uniformly respond to outer anthropogenic and natural stresses because a variety of human interventions are differently involved. [ABSTRACT FROM AUTHOR]

Pollution of groundwater by seawater intrusion poses a threat to sustainable agriculture in the coastal areas of Korea. Therefore, seawater intrusion monitoring stations were installed in eastern, western, and southern coastal areas and have been operated since 1998. In this study, groundwater chemistry data obtained from the seawater intrusion monitoring stations during the period from 2007 to 2009 were analyzed and evaluated. Groundwater was classified into fresh (<1,500 μS/cm), brackish (1,500-3,000 μS/cm), and saline (>3,000 μS/cm) according to EC levels. Among groundwater samples ( n = 233), 56, 7, and 37% were classified as the fresh, brackish, and saline, respectively. The major dissolved components of the brackish and saline groundwaters were enriched compared with those of the fresh groundwater. The enrichment of Na and Cl was especially noticeable due to seawater intrusion. Thus, the brackish and saline groundwaters were classified as Ca-Cl and Na-Cl types, while the fresh groundwater was classified as Na-HCO and Ca-HCO types. The groundwater included in the Na-Cl types indicated the effects of seawater mixing. Ca, Mg, Na, K, SO, and Br showed good correlations with Cl of over r = 0.624. Of these components, the strong correlations of Mg, SO, and Br with Cl ( r ≥ 0.823) indicated a distinct mixing between fresh groundwater and seawater. The Ca/Cl and HCO/Cl ratios of the groundwaters gradually decreased and approached those of seawater. The Mg/Cl, Na/Cl, K/Cl, SO/Cl, and Br/Cl ratios of the groundwaters gradually decreased, and were similar to or lower than those of seawater, indicating that Mg, Na, K, SO, and Br, as well as Cl in the saline groundwater can be enriched by seawater mixing, while Ca and HCO are mainly released by weathering processes. The influence of seawater intrusion was evaluated using threshold values of Cl and Br, which were estimated as 80.5 and 0.54 mg/L, respectively. According to these criteria, 41-50% of the groundwaters were affected by seawater mixing. [ABSTRACT FROM AUTHOR]

Porphyromonas gingivalis, a gram-negative anaerobic oral bacterium, causes periodontal disease by binding to saliva-coated oral surfaces. The FimA protein from P. gingivalis is a crucial pathogenic component of the bacterium and a target for vaccine development against periodontal disease. Complementary DNAs encoding the heavy and light chains of two monoclonal antibodies that bind specifically to the FimA protein were cloned into a plant expression vector under the control of the duplicated Cauliflower Mosaic Virus 35S promoter, and agroinfiltration was used to allow the vectors to infiltrate tobacco plants. The expressions of the heavy and light chains in the leaf tissue were detected using antibodies specific to each antibody chain. Western blot analysis showed the specific binding of the plant-derived monoclonal antibodies to the native FimA protein purified from P. gingivalis. Our finding that plant-derived monoclonal antibodies bound specifically to the native FimA protein indicates that plantderived monoclonal antibodies can protect against P. gingivalis invasion. [ABSTRACT FROM AUTHOR]

Widespread climate change can impact on groundwater conditions. We evaluated the groundwater data for 1996-2008 obtained from the National Groundwater Monitoring Stations (NGMS), in the context of the global warming effect. Indications of air temperature and sea level rises were evident in the period. The groundwater levels were generally decreasing and most of this decrease was attributed to increased pumping nationwide, but no indication for any effect of sea level rise on groundwater level in coastal aquifers was found. The electrical conductivity (EC) values of groundwaters were very high in metropolitan and industrial areas, which were indicative of anthropogenic groundwater contamination and progressive groundwater quality deterioration. A systematic EC rise in coastal groundwaters, as a possible result of the sea level rise, was not observed. The groundwater temperature variation was the most striking. The majority of the monitored shallow and deep groundwaters exhibited increasing trends at mean rates of 0.04-0.09 °C/yr. The widespread and prevailing increase in groundwater temperature nationwide, with increasing air temperature, is strongly indicative of the effect of global warming. The increasing trend became more distinctive every year. However, these significant conclusions require further groundwater monitoring and re-evaluation. [ABSTRACT FROM AUTHOR]

We examined levels of soil contamination by trichloroethylene (TCE) at an industrial complex in Wonju, Korea. The examination was focused on the surrounding area of an asphalt laboratory where TCE had been used as a solvent for testing the asphalt quality. TCE contamination in soil was found at depths of 1∼5 m and ranged between 0.13 and 14,702.82 mg/kg. However, the soil contamination was restricted in immediate proximity of the laboratory. Batch isotherm experiments showed that there was a linear relationship between the sorbed concentration and the aqueous TCE concentration, which is typical for non-polar organic chemicals such as TCE. The distribution coefficient (K) ranged between 0.375 and 0.639 L/kg and increased with depth. Considering TCE concentration in deep soil, K and higher groundwater level, TCE concentration in groundwater can reach up to 19.36 mg/L. In addition, highly weathered and fractured rocks, where groundwater level formed, underlain by the contaminated soil zone can facilitate vertical TCE movement and form an extensive groundwater plume in the downgradient area. As a source removal measure, the contaminated soil at the presumably hot source zone had been remediated in 2004. [ABSTRACT FROM AUTHOR]

Periodontal disease caused by the gram-negative oral anaerobic bacterium Porphyromonas gingivalis is thought to be initiated by the binding of P. gingivalis fimbrial protein to saliva-coated oral surfaces. To assess whether biologically active fimbrial antigen can be synthesized in edible plants, a cDNA fragment encoding the C-terminal binding portion of P. gingivalis fimbrial protein, fimA (amino acids 266–337), was cloned behind the mannopine synthase promoter in plant expression vector pPCV701. The plasmid was transferred into potato ( Solanum tuberosum) leaf cells by Agrobacterium tumefaciens in vivo transformation methods. The fimA cDNA fragment was detected in transformed potato leaf genomic DNA by PCR amplification methods. Further, a novel immunoreactive protein band of ~6.5 kDa was detected in boiled transformed potato tuber extracts by acrylamide gel electrophoresis and immunoblot analysis methods using primary antibodies to fimbrillin, a monomeric P. gingivalis fimbrial subunit. Antibodies generated against native P. gingivalis fimbriae detected a dimeric form of bacterial-synthesized recombinant FimA(266–337) protein. Further, a protein band of ~160 kDa was recognized by anti-FimA antibodies in undenatured transformed tuber extracts, suggesting that oligomeric assembly of plant-synthesized FimA may occur in transformed plant cells. Based on immunoblot analysis, the maximum amount of FimA protein synthesized in transformed potato tuber tissues was approximately 0.03% of total soluble tuber protein. Biosynthesis of immunologically detectable FimA protein and assembly of fimbrial antigen subunits into oligomers in transformed potato tuber tissues demonstrate the feasibility of producing native FimA protein in edible plant cells for construction of plant-based oral subunit vaccines against periodontal disease caused by P. gingivalis. [ABSTRACT FROM AUTHOR]

The gram-negative anaerobic oral bacterium Porphyromonas gingivalis initiates periodontal disease through fimbrial attachment to saliva-coated oral surfaces. To study the effects of immunomodulation on enhancement of subunit vaccination, the expression in E. coli and immunogenicity of P. gingivalis fimbrial protein (FimA) linked to the C-terminus of the cholera toxin B subunit (CTB) were investigated. Complementary DNAs encoding the P. gingivalis 381 fimbrillin protein sequence FimA1 (amino acid residues 1–200) and FimA2 (amino acid residues 201–337) were cloned into an E. coli expression vector downstream of a cDNA fragment encoding the immunostimulatory CTB. CTB-FimA1 and CTB-FimA2 fusion proteins synthesized in E. coli BL21 (DE3) cells were purified under denaturing conditions by Ni2+-NTA affinity column chromatography. Renaturation of the CTB-FimA1 and CTB-FimA2 fusion proteins, permitted identification of CTB-FimA pentamers and restored CTB binding activity to GM1-ganglioside to provide a biologically active CTB-FimA fusion protein. Mice orally inoculated with purified CTB-FimA1 or CTB-FimA2 fusion proteins generated measurable FimA1 and FimA2 IgG antibody titers, while no serum fimbrial IgG antibodies were detected when mice were inoculated with FimA1 or FimA2 proteins alone. Immunoblot analysis confirmed that sera from mice immunized with CTB linked to FimA1 or FimA2 contained antibodies specific for P. gingivalis fimbrial proteins. In addition, mice immunized with FimA2 or CTB-FimA2 generated measurable intestinal IgA titers indicating the presence of fimbrial antibody class switching. Further, mice orally immunized with CTB-FimA1 generated higher IgA antibody titers than mice inoculated with FimA1 alone. The experimental data show that the immunostimulatory molecule CTB enhances B cell-mediated immunity against linked P. gingivalis FimA fusion proteins, in comparison to immunization with FimA protein alone. Thus, linkage of CTB to P. gingivalis fimbrial antigens can increase subunit vaccine immunogenicity to provide enhanced protection against periodontal disease. [ABSTRACT FROM AUTHOR]

When leachate emanates from an uncontrolled landfill, it poses a threat to the groundwater resources of the surrounding areas. Thus, regular monitoring is essential to protect the groundwater from contamination. In this study, an evaluation is carried out on the quality of groundwater affected by the leachate deriving from an uncontrolled landfill situated in a valley. A nonparametric trend analysis revealed that alkalinity levels were increasing at most monitoring wells, indicating the continuous increase of biodegradation of organic matter. According to a cluster analysis, similar chemical groups developed in a parallel direction to that of groundwater flow. Each group indicates different redox levels and various degrees of landfill leachate effect. This geographical distribution of groups with similar chemical properties is closely associated with local groundwater flow and land surface permeability. However, an evaluation of the effect of recharge flow from the surrounding mountains and of the vertical component of groundwater in the recharge area is essentially required in order to enhance our understanding of redox zonation or distribution of groundwater quality affected by the landfill leachate. [ABSTRACT FROM AUTHOR]

Seawater intrusion was studied in a monitoring well field, located in western coastal area of Buan, Korea using groundwater chemistry and ionic ratios. Most of the study area is paddy fields apart from 200–2,500 m from the coast. The groundwaters affected by the seawater intrusion featured high levels of C1 and TDS, which are the simplest common indicators for the seawater influence. The TDS showed highly positive correlation with the other major parameters except for nitrate. High levels of NO3 at some monitoring wells indicated nitrate pollution of groundwaters due to anthropogenic origin such as septic effluents or chemical fertilizers. Based on the piper plot, it was inferred that the groundwater salinization occurred via mixing and cation exchange reaction between two end members (fresh or less affected groundwater and the seawater). Beside of the major chemical compositions, it was demonstrated that ionic ratios would be useful to delineate seawater intrusion and they include HCO3/Cl Na/Ca, Ca/Cl, Mg/Cl and Ca/SO4. Cluster analysis based on these ratios produced an equivalent result to that of using the major chemical compositions. Finally, to differentiate causes of the high salinity in groundwaters between anthropogenic origin (excessive groundwater use) and natural phenomenon (seawater intrusion wedge), consecutive monitoring of groundwater is required for multi-years. [ABSTRACT FROM AUTHOR]

Seawater intrusion is a problem in the coastal areas of Korea. Most productive agricultural fields are in the western and southern coastal areas of the country where irrigation predominantly relies on groundwater. Seawater intrusion has affected agricultural productivity. To evaluate progressive encroachment of saline water, the Korean government established a seawater intrusion monitoring well network, especially in the western and southern part of the peninsula. Automatic water levels and EC monitoring and periodic chemical analysis of groundwater help track salinization. Salinization of fresh groundwater is highly associated with groundwater withdrawal. A large proportion of the groundwaters are classified as Na–Cl and Ca–Cl types. The Na–Cl types represent effects of seawater intrusion. The highest EC level was over 1.6 km inland and high Cl values were observed up to 1.2 km inland. Lower ratios of Na/Cl and SO4/Cl than seawater values indicate the seawater encroachment. A linear relation between Na and Cl represents simple mixing of the fresh groundwater with the seawater. The saline Na–Cl typed groundwaters showed Br/Cl ratios similar to or less than seawater values. The Ca–HCO3 type groundwaters had the highest Br/Cl ratios. Substantial proportions of the groundwaters showed potential for salinity and should be better managed for sustainable agriculture. [ABSTRACT FROM AUTHOR]