ABSTRACT
We comprehensively analyzed sediments obtained from an archeological excavation. A trench sediment profile of Maedun Cave (MC), South Korea, was analyzed geoarchaeologically. Multi‐proxy ...analyses (palynomorphs, grain size, magnetic susceptibility, animal bones and artifacts) reflected the vegetation, hydroclimate and lives of prehistoric people at Marine Isotope Stage (MIS) 3 (ca. 40–30k cal a bp) in the early Late Paleolithic. The palynoflora consisted of pollen and non‐pollen palynomorphs. Under the air‐circulation system in the cave, anemophilous pollen flowed in during the day, whereas waterborne pollen and spores, and freshwater algae, were transported by flooding during the summer monsoon rainy season. Mixed conifer and deciduous broad‐leaved forest with an understory of pteridophytes flourished around the north‐east central Korean Peninsula during MIS 3. Freshwater algae and grass pollen records may reflect precipitation intensity. It is assumed that they had flowed in during flooding caused by high precipitation during the enhanced East Asian summer monsoon, corresponding to Dansgaard–Oeschger (D/O) events 5 and 8 of δ18O GISP2 and Hulu Cave. The prehistoric people hunted herbivorous animals in the area around MC and sheltered inside it seasonally. They also used the grains of oats growing near the dwelling as a source of food.
Highlights
Multi‐proxy records from cave sediments of the Korean Peninsula shed light on vegetation cover and climate conditions during MIS 3 (40–30k cal a BP).
Herbaceous pollen and non‐pollen palynomorphs flowed into the cave due to flooding caused by high precipitation under the enhanced East Asia summer monsoon.
Fossilized mammal bones and artifacts shed light on the lifestyle of prehistoric people in the early Late Paleolithic.
Geoarchaeological evidence provides insight into the responses of ancient societies to climate conditions in northeast central Korea.
Using a methanotrophic consortium (that includes
Methylosinus sporium
NCIMB 11126,
Methylosinus trichosporium
OB3b, and
Methylococcus capsulatus
Bath) isolated from a landfill site, the potential for ...partial oxidation of methane into methanol through selective inhibition of methanol dehydrogenase (MDH) over soluble methane monooxygenase (sMMO) with some selected MDH inhibitors at varied concentration range, was evaluated in batch serum bottle and bioreactor experiments. Our result suggests that MDH activity could effectively be inhibited either at 40 mM of phosphate, 100 mM of NaCl, 40 mM of NH
4
Cl or 50 μM of EDTA with conversion ratios (moles of CH
3
OH produced per mole CH
4
consumed) of 58, 80, 80, and 43 %, respectively. The difference between extent of inhibition in MDH activity and sMMO activity was significantly correlated (
n
= 6,
p
< 0.05) with resultant methane to methanol conversion ratio. In bioreactor study with 100 mM of NaCl, a maximum specific methanol production rate of 9 μmol/mg h was detected. A further insight with qPCR analysis of MDH and sMMO coding genes revealed that the gene copy number continued to increase along with biomass during reactor operation irrespective of presence or absence of inhibitor, and differential inhibition among two enzymes was rather the key for methanol production.
Ultrafine particles (UFPs, < 2.5 µm) in air pollutants have been identified as a major cause of respiratory diseases, since they can affect the lung alveoli through the bronchus. In particular, if ...toxicants such as heavy metals and polycyclic aromatic hydrocarbons (PAHs) are present in UFPs, they can cause diseases such as asthma, chronic obstructive pulmonary disease, and lung cancer. This study compared in vitro toxicity of various particulate matter including UFPs from combustion particles of diesel (diesel exhaust particles (DEP)), rice straw (RS), pine stem (PS) and coal (CC), and road dust particles from tunnel (TD) and roadside (RD). UFPs from combustion particles and road dust were collected with a glass fiber filter using burning systems and a solid aerosol generator. Cell viability was determined by neutral red uptake assay using Chinese hamster ovary strain K1 cells. Redox cycling activity and intracellular reactive oxygen species were measured using 1,4-dithiothreitol (DTT) and 2′,7′-dichlorofluorescin diacetate (DCF-DA) assay, respectively. Our in vitro studies validated that combustion particles had high toxicological activity. PS demonstrated the highest activity in cytotoxicity but DEP had the highest activity in the DTT and DCF-DA assays. Overall, since the toxicological activity of particles generated by various means was different, risk assessment should be conducted through various toxicity evaluations rather than one toxicity evaluation.
Methane in a simulated biogas converting to methanol under aerobic condition was comparatively assessed by inhibiting the activity of methanol dehydrogenase (MDH) of Methylosinus sporium using ...phosphate, NaCl, NH ₄Cl or EDTA in their varying concentrations. The highest amount of methane was indistinguishably diverted at the typical conditions regardless of the types of inhibitors: 35°C and pH 7 under a 0.4% (v/v) of biogas, specifically for <40 mM phosphate, 50 mM NaCl, 40 mM NH ₄Cl or 150 µM EDTA. The highest level of methanol was obtained for the addition of 40 mM phosphate, 100 mM NaCl, 40 mM NH ₄Cl or 50 µM EDTA. In other words, 0.71, 0.60, 0.66 and 0.66 mmol methanol was correspondingly generated by the oxidation of 1.3, 0.67, 0.74 and 1.3 mmol methane. It gave a methanol conversion rate of 54.7%, 89.9%, 89.6% and 47.8%, respectively. Among them, the maximum rate of methanol production was observed at 6.25 µmol/mg h for 100 mM NaCl. Regardless of types or concentrations of inhibitors differently used, methanol production could be nonetheless identically maximized when the MDH activity was limitedly hampered by up to 35%.
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•Complete combustion of coal at 700 °C generated more toxins than at 500 or 900 °C.•Mutagenicity, cytotoxicity, redox cycling, and ROS production were highest at 700 °C.•Particles ...generated at 700 °C are more toxic due to a higher toxic compound content.•Benzo(a)pyrene may have the greatest effect on ROS production.
Herein, the toxicity of particles generated from the complete combustion of 1 g coal at 500, 700, and 900 °C were compared, and combustion at 700 °C generated the most toxins. Chemical analyses revealed that all components except catechol, resorcinol, and aromatic amines were most abundant at 700 °C. Toxicity results confirmed that the relative mutagenicity, cytotoxicity, redox cycling, and production of reactive oxygen species was highest for particles generated at 700 °C. Particles generated during combustion at 700 °C exhibited higher toxicity toward biological systems due to a higher content of toxic compounds.
•KRG attenuated mRNA expression of spermatogenesis in DOX-induced rat testis.•KRG inhibited the DOX-induced inflammatory activation in rat testis.•KRG ameliorated the changes in DOX-induced mTORC ...expression in rat testis.
The effect of Korean red ginseng (KRG; Panax ginseng Meyer) against doxorubicin (DOX)-induced testicular inflammation was investigated. Male Sprague-Dawley rats were treated with DOX (1 mg mL−1 kg−1 week−1; intra-peritoneally) for 8 weeks, and KRG water extract (EX1; 100 and EX2; 200 mg/kg/day; orally) was administered for 9 weeks starting one week before DOX exposure. The expression levels related to spermatogenesis, inflammatory and autophagy markers were evaluated using western blotting and reverse transcriptase polymerase chain reaction. DOX-induced a significant (p < .05) alteration in the expression of antioxidation spermatogenesis and sex hormone receptors genes when compared with control groups, which were attenuated with KRG-WE treatment significantly (p < .05 ∼ p < .01). KRG-WE also ameliorated the DOX-induced alteration in pro-inflammatory cytokines via the mitogen-activated protein kinases/nuclear factor kappa-B pathway and autophagy in the testes of rats. In conclusion, KRG might be used as a functional food for prevention of chemotherapy-induced testicular inflammation.
A robust, naturally evolving methanotrophic community in landfill cover soil (LFCS) can be the simplest way to mitigate landfill methane emission. In this study, bacterial community composition in ...LFCS and methane oxidation potential of enriched methanotrophic consortium, in comparison to that of axenic Methylosinus sporium, was investigated. Growth and methane oxidation of the consortium was studied in liquid phase batch experiments under varying temperature (20-40°C), pH (5-10), headspace CO2, and in presence of porous adsorbent (1.3 cm
3
sponge cubes). The 16S rRNA gene analysis revealed presence of both type-I and type-II methanotrophs along with few obligate methylotroph in LFCS. Though the optimal growth condition of the consortium was at 30°C and pH 7, it was more resilient in comparison to M. sporium. With increasing availability of porous adsorbent, methane consumption by the consortium was significantly improved (p < 0.001) reaching a maximum specific methane oxidation rate of 11.4 μmol mg
−1
biomass h
−1
. Thus, inducing naturally thriving methanotrophs in LFCS is a better alternative to axenic methanotrophic culture in methane emission management.
Cold cathode fluorescent lamps (CCFLs) show complex characteristics, which make it difficult to drive them in parallel. In this paper, a backlight inverter, which can drive multiple CCFLs using ...single controller and single switching network, is presented. The analysis of the lamp current distribution is presented in detail. The current-balancing condition, under which the lamp currents are well balanced in the presence of the lamp voltage variation, is derived. The effect of the resonant component variation is also investigated. The analysis results are verified from experiments with two 720-mm/4-mm CCFLs for 32-in liquid crystal display televisions. Experimental results with eight CCFLs are also presented in the presence of the lamp voltage and the resonant component deviation
Air pollution is increasing, along with consumption of fossil fuels such as coal and diesel gas. Air pollutants are known to be a major cause of respiratory-related illness and death, however, there ...are few reports on the genotoxic characterization of diverse air pollutants in Korea. In this study, we investigated the mutagenic activity of various particles such as diesel exhaust particles (DEP), combustion of rice straw (RSC), pine stem (PSC), and coal (CC), tunnel dust (TD), and road side dust (RD). Ultra-fine particles (UFPs) were collected by the glass fiber filter pad. Then, we performed a chemical analysis to see each of the component features of each particulate matter. The mutagenicity of various UFPs was determined by the Ames test with four
Salmonella typhimurium
strains with or without metabolic activation. The optimal concentrations of UFPs were selected based on result of a concentration decision test. Moreover, in order to compare relative mutagenicity among UFPs, we selected and tested DEP as mutation reference. DEP, RSC, and PSC induced concentration-dependent increases in revertant colony numbers with TA98, TA100, and TA1537 strains in the absence and presence of metabolic activation. DEP showed the highest specific activity among the particulate matters. In this study, we conclude that DEP, RSC, PSC, and TD displayed varying degrees of mutagenicity, and these results suggest that the mutagenicity of these air pollutants is associated with the presence of polycyclic aromatic hydrocarbons (PAHs) in these particulate matters.
Escherichia coli O157:H7 is a major food-borne infectious pathogen that causes diarrhea, hemorrhagic colitis, and hemolytic uremic syndrome. Here we report the complete chromosome sequence of an ...O157:H7 strain isolated from the Sakai outbreak, and the results of genomic comparison with a benign laboratory strain, K-12 MG1655. The chromosome is 5.5 Mb in size, 859 Kb larger than that of K-12. We identified a 4.1-Mb sequence highly conserved between the two strains, which may represent the fundamental backbone of the E. coli chromosome. The remaining 1.4-Mb sequence comprises of O157:H7-specific sequences, most of which are horizontally transferred foreign DNAs. The predominant roles of bacteriophages in the emergence of O157:H7 is evident by the presence of 24 prophages and prophage-like elements that occupy more than half of the O157:H7-specific sequences. The O157:H7 chromosome encodes 1632 proteins and 20 tRNAs that are not present in K-12. Among these, at least 131 proteins are assumed to have virulence-related functions. Genome-wide codon usage analysis suggested that the O157:H7-specific tRNAs are involved in the efficient expression of the strain-specific genes. A complete set of the genes specific to O157:H7 presented here sheds new insight into the pathogenicity and the physiology of O157:H7, and will open a way to fully understand the molecular mechanisms underlying the O157:H7 infection.
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