Polymeric graphitic carbon nitride (g-C3N4) is an emerging metal-free and visible-light-active photocatalyst with much interest in various fields such as environmental and biomedical fields. The ...creation of photocatalysts as micro nanomotors, which can perform reactions in micro nanoscales in complex environments has widened their utility in those fields. g-C3N4 can act as a photocatalyst and adsorbent, hence they are widely used in environmental remediation. This applicability opens up their extension in micro and nanomotor fields. This review focuses on the fundamentals and applications of g-C3N4 micromotors, especially in environmental remediation. Depending on the morphology of the supporting materials, the g-C3N4 micromotor undergoes self-electrophoresis, self-diffusiophoresis, or bubble propulsion to move through the matrix under visible light irradiation. The motion of the particle simultaneously results in the generation of various reactive oxygen species and is utilized in the degradation of organic pollutants. The main advantage of g-C3N4 micromotors is that it does not require any toxic metal support and hence, can be applied in environmental remediation with minimal secondary pollution. However, most of the studies discussed in this review were carried out on a laboratory scale with limited solution volume. Therefore, a more comprehensive analysis is necessary for the implementation of the material in large-scale applications.
•Reviewed the application of g-C3N4 in micromotor applications.•Discussed the propulsion mechanism of various g–C3N4–based micromotors.•g–C3N4–based micromotors are effective in the degradation of water pollutants.•Suggestions for the improvement of the activity of g-C3N4 are given.
Purpose
Chronic cough is a common problem in various populations. The present study assessed the impact of cough and unmet needs in Korean patients with chronic cough.
Methods
This cross-sectional ...multi-center study enrolled adult patients newly referred to clinic for assessment of chronic cough. A second group of patients with unexplained chronic cough following detailed assessment were recruited for comparison. Patients completed self-reported questionnaires, including cough characteristics, impact of cough on daily life, and unmet needs.
Results
A total of 447 subjects were recruited from six referral clinics, including 408 with chronic cough and 39 with unexplained chronic cough. Almost all patients reported that cough impacted their daily lives. Psychosocial impacts were more evident in unexplained cough patients compared to newly referred patients. Approximately 75% of newly referred patients had previously sought medical care for cough on multiple occasions, but the effectiveness of treatment was limited (70.3%) or absent (17.3%). The most frequent unmet need was the ineffectiveness of treatment (49.3%), followed by unclear diagnosis (30.1%). The majority of participants ( > 80%) expressed the need for further information on accessing cough specialists and disease management. The main problem faced by unexplained cough patients was poor cough control despite treatment (64%).
Conclusions
Chronic cough has a substantial impact on daily life and is worst in those whose cough remains unexplained following assessment. Ineffectiveness of treatment and unclear diagnosis were major unmet needs. Medical information about chronic cough was also lacking. Improvements in the management of chronic cough patients in Korea are necessary.
Dye decolorizing potential of the white rot fungus
Ganoderma lucidum KMK2 was demonstrated for recalcitrant textile dyes.
G. lucidum produced laccase as the dominant lignolytic enzyme during solid ...state fermentation (SSF) of wheat bran (WB), a natural lignocellulosic substrate. Crude enzyme shows excellent decolorization activity to anthraquinone dye Remazol Brilliant Blue R (RBBR) without redox mediator whereas diazo dye Remazol Black-5 (RB-5) requires a redox mediator. Polyacrylamide gel electrophoresis (PAGE) of crude enzyme confirms that the laccase enzyme was the major enzyme involved in decolorization of either dyes. Native and SDS-PAGE indicates that the presence of single laccase with molecular weight of 43
kDa.
N-Hydroxybenzotriazole (HBT) at a concentration of 1
mM was found as the best redox mediator. RB-5 (50
mg
l
−l) was decolorized by 62% and 77.4% within 1 and 2
h, respectively by the crude laccase (25
U
ml
−1). RBBR (50
mg
l
−l) was decolorized by 90% within 20
h, however, it was more efficient in presence of HBT showing 92% decolorization within 2
h. Crude laccase showed high thermostability and maximum decolorization activity at 60
°C and pH 4.0. The decolorization was completely inhibited by the laccase inhibitor sodium azide (0.5
mM). Enzyme inactivation method is a good method which averts the undesirable color formation in the reaction mixture after decolorization. High thermostability and efficient decolorization suggest that this crude enzyme could be effectively used to decolorize the synthetic dyes from effluents.
Dechlorane compounds, including Dechlorane Plus (DP), mirex, and Dechlorane (Dec) 602, 603 and 604, were measured in 61 serum samples collected from a Korean urban area (Seoul) in 2013. Dechlorane ...Plus and Dec 602 were dominant in most samples, whereas Dec 604 was not detected in any samples. The median value of DP was 0.75 ng/g lipid, which was comparable with the levels observed in Europe and Canada, but lower than that observed in China. Statistically significant correlations among Dechlorane compounds were observed. The median anti-isomer fractional abundance (fanti) was 0.74, and a negative correlation between fanti and the DP concentration in serum samples was observed. Polybrominated diphenyl ethers (PBDEs) were also measured for comparison with Dechlorane compounds, and BDE-153 was found the most abundant congener with a median value of 1.43 ng/g lipid. A time trend of Dechlorane compounds was investigated in 7 pooled serum samples to cover the period from 2006 to 2013. A distinct trend of Dechlorane compounds was not observed, while PBDEs steadily decreased with time.
•We investigated the occurrence of halogenated flame retardants in Korea.•The concentrations of Dechlorane compounds in 7 pooled serum samples were measured.•PBDEs were also measured for comparison with Dechlorane compounds.•A negative correlation between fanti and the total DP concentrations was observed.
This study provides not only the contamination status but also the current trend of Dechlorane compounds and PBDEs.
Heavy metals and persistent organic pollutants (POPs), including Pb, Cd, T-Hg, MeHg, PCDD/Fs, PCBs, PBDEs, PCNs, and PBDD/Fs, were analyzed in 20 paired samples of cord blood, maternal blood, ...maternal urine, and placenta. The samples were collected from pregnant mothers and neonates from South Korea in 2010. The distribution of heavy metals among the samples varied with their physicochemical characteristics. The concentrations of Pb and Hg in the maternal and the cord blood samples were significantly correlated each other, implying efficient transplacental transport (TPT). Cd and Hg were accumulated in the placenta, forming protein conjugates, and T-Hg was higher in the cord blood samples than the maternal blood samples due to the binding affinity of Hg with fetal proteins. POPs generally showed the highest concentrations in the maternal serum samples, and the POPs levels in the cord serum and the placenta samples were dependent on the degree of halogenation. The TPT of POPs was seemingly related to lipoprotein transportation. Some PBDE congeners, however, showed their highest concentrations in the cord serum samples, suggesting an additional TPT mechanism. This is the first study to detect PCNs and PBDD/Fs in the cord serum samples, showing that the PCN levels were comparable to other POPs. According to the principal component analysis (PCA) results of the contaminant levels, POPs and heavy metals showed significantly different characteristics, whereas PBDEs had an intermediate attribute. Despite the limited number of participants, the comprehensive analysis of trace contaminants in the paired sample sets enabled us to infer the distribution and TPT mechanism of various contaminants.
Increasing contamination of groundwater by heavy metals could potentially hamper the basic sanitation based on septic system in developing countries. Therefore, this paper evaluated wastewater ...treatment by electrochemical activation of hydrogen peroxide (EAHP), persulfate (EAP), and free chlorine (EAFC) to simultaneously eliminate aqueous organic matter and heavy metals. Sacrificial iron anodes under galvanostatic regime activated the batch-injected oxidants under uncontrolled pH, to avoid extra cost of control in decentralized processes (e.g., household use) to treat domestic wastewater. Response surface methodology (RSM) was used to determine the optimized conditions for EAP (persulfate0 = 25 mM, 24.4 mA/cm2), EAFC (free chlorine0 = 35.5 mM, 44.4 mA/cm2), and EAHP (H2O20 = 91.1 mM, 45 mA/cm2) towards total organic carbon (TOC) removal. Treatment of real wastewater under optimum conditions significantly reduced chemical oxygen demand (COD) and TOC in all treatments, complying with lenient effluent standards as well as the added benefit of complete As(V) and Cr(VI) removal. Although EAP and EAFC provided superior removal of TOC (70−75%) and COD (73–100%) within 3 h, respectively, effluent toxicity and operation cost (76–85 USD/m3) were relatively high. EAHP was the best available option to secure non-toxic effluent with the least cost (63 USD/m3).
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•Galvanostatic iron anodes activated persulfate, free chlorine, and H2O2.•Current density and added oxidants were optimized for decentralized water treatment.•Primary oxidants (HO•, SO4•- and Fe(IV) species) were identified.•Treatment of real domestic wastewater complied with effluent standards.•H2O2 activation provided the lowest operational cost and effluent toxicity.
1,2,5,6,9,10-hexabromocyclododecane (HBCD) is a brominated flame retardant that is used worldwide in expanded and extruded polystyrene foam and simultaneously emitted to the environment. HBCD can ...easily accumulate in animals and humans and cause neurotoxicity, thyroid hormone disruption, and reproductive disorders. Therefore, it is essential to monitor the HBCD concentrations in foods and estimate the human exposure through the diet. In this study a total of 521 food samples from eight food categories were sampled and analyzed for their HBCD content. Based on consumption data, the average dietary intake of the general Korean population and specific subgroups was calculated. The highest levels of HBCD were found in fish and shellfish (0.47 ng g−1 ww), and this was attributed to natural exposure to the contaminated marine environments and the HBCD bioaccumulation. In addition, the use of expanded polystyrene buoys in aquaculture was also found to be a potential source of HBCD in bivalves. The high solubility of α-HBCD in water and the persistence of this diastereomer compared to β- and γ-HBCD in biological tissues, led to higher accumulation of α-HBCD in animal-based foods. In contrast, the diastereomeric selectivity and lower metabolic capacity in plants compared with animals led to the predominance of γ-HBCD in plant-based foods. The dietary intake of HBCD was estimated to be 0.82 ng kg−1 bw d−1 in the general population and 2.89 ng kg−1 bw d−1 in children up to 5 years of age. The high HBCD intake in children was found to be a result of their lower body weight and their high consumption of milk and homemade Korean baby foods that usually contain fish.
•∑HBCD concentrations in 521 food samples ranged from ND to 4.90 ng g−1 ww.•Animal-based foods contained higher concentrations of HBCD than plant-based foods.•α-HBCD was found the predominant diastereomer in animal-based food samples.•The EDI of ∑HBCD was 0.82 ng kg−1 bw d−1 in the Korean general population.•Toddlers were found to have the highest exposure to ∑HBCD.
This study provides the first data on diastereomer-specific HBCD levels in a variety of food categories and estimation of dietary intake in South Korea.
Large amounts of micro- and nanoplastics, which are released into the environment through environmental weathering of plastic items or sludge disposal/application, can end up in soil, being ...considered as a new plant abiotic stressor. In nature, plants face a number of abiotic stresses simultaneously. However, it is largely unknown whether and how abiotic stress combination affects the plant uptake of nanoplastics, and how plants tune the rhizosphere interactions to acclimate to a combination of nanoplastic and another abiotic stress. Here we show that smaller, fragmented nanoplastics can accumulate in the root of
Arabidopsis thaliana
under combined nanoplastic and Cd stresses. The specific changes in root exudation of organic acids and bacterial community composition that reveals a metabolic preference for aromatic compounds drive the degradation of nanoplastics in the rhizosphere. Our findings provide critical implications relevant to food security that nanoplastics will contaminate crops as well, and in turn, transfer along the human food chain.
Plants can take up the fragmented nanoplastics generated by plant-microbe rhizosphere interactions upon combined exposure to cadmium and nanoplastics.
