Almost all heavy metals are serious toxicants as carcinogens. However, due to their chemical and physiological properties, heavy metals are useful in industrial areas including alloy, smelting and production of commercial products. Such applications increase the opportunity for heavy metal exposure. Waste from industrial processes is also a major source of environmental contamination and accumulation in the human body. Arsenic, cadmium, chromium, and nickel are classified as group 1 carcinogens by the International Agency for Research on Cancer, and are utilized commercially. In this review, we used molecular pathway analysis to understand the toxicity and carcinogenic mechanisms of these metals. Our analyzed data showed that above-mentioned metallic substances induce oxidative stress, DNA damage, and cell death processes, resulting in increase the risk of cancer and cancer-related diseases. Thus, we might think phytochelatin molecules and antioxidative phytochemical substances are helpful for prevention of heavy metal-induced cancer.

IMPORTANCE There is limited information describing the full spectrum of coronavirus disease 2019 (COVID-19) and the duration of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) RNA detection in children. OBJECTIVE To analyze the full clinical course and the duration of SARS-CoV-2 RNA detectability in children confirmed with COVID-19 in the Republic of Korea, where rigorous public health interventions have been implemented. DESIGN, SETTING, AND PARTICIPANTS This case series of children with COVID-19 was conducted in 20 hospitals and 2 nonhospital isolation facilities across the country from February 18, 2020, to March 31, 2020. Children younger than 19 years who had COVID-19 were included. EXPOSURES Confirmed COVID-19, detected via SARS-CoV-2 RNA in a combined nasopharyngeal and oropharyngeal swab or sputum by real-time reverse transcriptionpolymerase chain reaction. MAIN OUTCOMES AND MEASURES Clinical manifestations during the observation period, including the time and duration of symptom occurrence. The duration of SARS-CoV-2 RNA detection was also analyzed. RESULTS A total of 91 children with COVID-19 were included (median [range] age, 11 [0-18] years; 53 boys [58%]). Twenty children (22%) were asymptomatic during the entire observation period. Among 71 symptomatic cases, 47 children (66%) had unrecognized symptoms before diagnosis, 18 (25%) developed symptoms after diagnosis, and only 6 (9%) were diagnosed at the time of symptom onset. Twenty-two children (24%) had lower respiratory tract infections. The mean (SD) duration of the presence of SARS-CoV-2 RNA in upper respiratory samples was 17.6 (6.7) days. Virus RNA was detected for a mean (SD) of 14.1 (7.7) days in asymptomatic individuals. There was no difference in the duration of virus RNA detection between children with upper respiratory tract infections and lower respiratory tract infections (mean [SD], 18.7 [5.8] days vs 19.9 [5.6] days; P = .54). Fourteen children (15%) were treated with lopinavir-ritonavir and/or hydroxychloroquine. All recovered, without any fatal cases. CONCLUSIONS AND RELEVANCE In this case series study, inapparent infections in children may have been associated with silent COVID-19 transmission in the community. Heightened surveillance using laboratory screening will allow detection in children with unrecognized SARS-CoV-2 infection.

In this study, sulfur-doped graphene (S-graphene) was synthesized by thermal treatment of exfoliated graphene under CS2 gas flow. Its electrocatalytic activity as a metal-free catalyst was evaluated and compared with other doped-graphenes and commercial platinum nanoparticles loaded on carbon black (Pt/C) catalysts for oxygen reduction reaction (ORR) in fuel cell cathodes. The resultant S-graphene was shown to act as a viable catalyst for ORR and its limiting current density and durability were improved compared to those of the commercial Pt/C catalyst. The current density at -1.0 V for the commercial Pt/C catalyst, pristine graphene, nitrogen-doped graphene (N-graphene) and S-graphene was 4.7, 0.15, 6.26 and 6.99 mA cm(-2), respectively. The durability of S-graphene (70.3%) was much better compared to commercial Pt/C (37.2%) and N-graphene (67.9%). When S-graphene was used as a supporting material for Pt nanoparticles, its catalytic performance was significantly higher than other Pt catalysts supported on different doped graphenes. Here, we demonstrate that S-graphene can be used as a novel graphene-based efficient metal-free ORR catalyst in fuel cells.

Our findings suggest that WMH-related cortical thinning as well as disrupted integrity of periventricular WM is linked to gait disturbances.