Concave Structural Carbon Co-Doped with Iron Atom Pairs and Nitrogen as Ultra-High Performance Catalyst Toward Oxygen Reduction.

It is crucial to rationally design and synthesize atomic-scale transition metal-doped carbon catalysts with high electrocatalytic activity to achieve a high-efficient oxygen reduction reaction (ORR). Herein, an electrocatalyst comprised of Fe-Fe dual atom pairs and N-doped concave carbon are reported (N-CC@Fe DA) that achieves ultrahigh electrocatalytic ORR activity. The catalyst is prepared by a gaseous doping approach, with zeolitic imidazolate framework-8 (ZIF-8) as the carbon framework precursor and cyclopentadienyliron dicarbonyl dimer as the Fe-Fe atom pair precursor. The catalyst exhibits high cathodic ORR catalytic performance in an alkaline Zn/air battery and proton exchange membrane fuel cell (PEMFC), yielding peak power densities of 241 mW cm-2 and 724 mW cm-2, respectively, compared to 127 mW cm-2 and 1.20 W cm-2 with conventional Pt/C catalysts as cathodes. The presence of Fe atom pairs coordinate with N atoms is revealed by X-ray photoelectron spectroscopy (XPS) and X-ray absorption spectroscopy (XAS) analysis, and Density Functional Theory (DFT) calculation results show that the Fe-Fe pair structure is beneficial for adsorbing oxygen molecules, activating the O─O bond, and desorbing OH* intermediates formed during oxygen reduction, resulting in a more efficient oxygen reaction. The findings may provide a new pathway for preparing ultra-high-performance doped carbon catalysts with Fe-Fe atom pair structures.

Enhancement of repeated applications of chelates on phytoremediation of uranium contaminated soil by Macleaya cordata.

A greenhouse pot experiment was performed to investigate the enhancement of repeated applications of citric acid (CA), ethylenediamine disuccinic acid (EDDS), and Oxalic acid (OA) on phytoremediation of uranium (U) contaminated soil by Macleaya Cordata. The chelates followed the order CA > EDDS > OA in terms of the enhancement on uranium uptake by M. cordata. The repeated applications of the chelates were found to be more effective than the one time application at the equal dose as the U concentration of soil solution increased significantly from the 8th to 14th day. The repeated applications of 10 mmol kg-1 CA promoted the solubilization of U in the U-contaminated soil by significantly decreasing the pH of soil solution, achieved the maximum U concentration of soil solution (1463.6 µg L-1), bioconcentration factors (BCFs, 11.4), bioaccumulation factors (BAFs, 21.4) and transfer factors (TFs, 1.9), which were 215.2, 5.7, 30.6 and 16.3 times as compared with the control group, respectively. The three applied chelates significantly affected the activities of the antioxidant enzymes in the leaves. Repeated applications of CA further enhanced the activities of the antioxidant enzymes in the leaves of M. cordata as compared with the control, EDDS and OA, mitigated the oxidative stress induced by uranium and chelates, and maximized the enhancement on the uranium uptake, which will be beneficial for the enhancement on the phytoremediation of uranium contaminated soil by U hyperaccumulating plants. These results indicated that the phytoavailability of uranium in soil solution as well as the accumulation of U by M. cordata were both significantly increased after repeated applications of CA, and that the repeated applications of 10 mmol kg-1 CA increased the activities of the antioxidant enzymes and promoted U accumulation by M. cordata. The study provided an environmentally friendly alternative for the enhancement on the phytoremediation of uranium contaminated soil using M. cordata.

Relationship between caregivers' smoking at home and urinary levels of cotinine in children.

OBJECTIVE: To assess the impact of different smoking behaviors of caregivers on environmental tobacco smoke (ETS) exposure in children aged 5-6 years in Changsha, China. METHODS: We conducted a cross-sectional, random digit-dial telephone survey of caregivers (n = 543) between August and October 2013. Caregivers' smoking behaviors were collected by a questionnaire. Exposure assessment was based upon determination of urinary cotinine levels in children employing gas chromatography-triple quadrupole mass spectrometry (GC-MS/MS). RESULTS: In children not living with a smoker, children living with one smoker, and children living with more than one smoker at home, median urinary cotinine concentrations (ng/mL) were 0.72, 2.97, and 4.46, respectively. For children living with one smoker, median urinary cotinine levels of children exposed to ETS were associated with caregiver smoking behaviors, i.e., if a caregiver consumed more cigarettes (>20 compared with ≤10; 7.73 versus 2.29 ng/mL, respectively). CONCLUSIONS: The magnitude of ETS exposure in children is correlated with the smoking behaviors of the caregiver. Counseling for smoking cessation and educational interventions are needed urgently for smoking caregivers to increase their awareness about ETS exposure and to encourage smoking cessation at home or to take precautions to protect children's health.

Meta-analysis of cytochrome P-450 2C9 polymorphism and colorectal cancer risk.

BACKGROUND: CYP2C9 encodes a member of the cytochrome P450 superfamily of enzymes which play a central role in activating and detoxifying many carcinogens and endogenous compounds thought to be involved in the development of colorectal cancer (CRC). In the past decade, the relationship between CYP2C9 common polymorphisms (R144C and I359L) and CRC has been reported in various ethnic groups; however, these studies have yielded contradictory results. To investigate this inconsistency, we performed this meta-analysis. METHODS: Databases including Pubmed, EMBASE, Web of Science and China National Knowledge Infrastructure (CNKI) were searched to find relevant studies. Odds ratios (ORs) with 95% confidence intervals (CIs) were used to assess the strength of association. RESULTS: A total of 13 articles involving 9,463 cases and 11,416 controls were included. Overall, the summary odds ratio of CRC was 0.98 (95% CI: 0.89-1.06) and 0.99 (95% CI: 0.87-1.14) for CYP2C9 144C and 359L alleles, respectively. No significant results were observed using dominant or recessive genetic model for these polymorphisms. In the stratified analyses according to ethnicity and sex, no evidence of any gene-disease association was obtained. CONCLUSIONS: This meta-analysis suggests that the CYP2C9 may not be associated with colorectal cancer development.

[Inhibition of the expression of p42MAPK in HeLa cell line by RNA interference].

OBJECTIVE: To screen for siRNAs that inhibit the expression of p42(MAPK) in HeLa cell line. METHODS: Three p42(MAPK) siRNAs and one random siRNA were synthesized using Silencer siRNA Construction Kit, and labeled with Cy-3 for measurement of transfection effect. SiRNAs were transfected into HeLa cells by Lipofectamin 2000. The expression of p42(MAPK) was analyzed by Western blot. The biological effect of siRNAs on HeLa cell growth was monitored by MTT and flow cytometry. RESULTS: Two siRNAs (siRNA-2 and siRNA-3) among three tested were identified to be able to downregulate the p42(MAPK) expression. A concurrent growth retardation of HeLa cell line was observed in comparison with the control. CONCLUSION: Inhibition of p42(MAPK) expression with siRNA technique can inhibit the proliferation of HeLa cells.

Apoptosis of pancreatic cancer BXPC-3 cells induced by indole-3-acetic acid in combination with horseradish peroxidase.

AIM: To explore the mechanisms underlying the apoptosis of human pancreatic cancer BXPC-3 cells induced by indole-3-acetic acid (IAA) in combination with horseradish peroxidase (HRP). METHODS: BXPC-3 cells derived from human pancreatic cancer were exposed to 40 or 80 micromol/L IAA and 1.2 microg/mL HRP at different times. Then, MTT assay was used to detect the cell proliferation. Flow cytometry was performed to analyze cell cycle. Terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling assay was used to detect apoptosis. 2,7-Dichlorofluorescin diacetate uptake was measured by confocal microscopy to determine free radicals. Level of malondialdehyde (MDA) and activity of superoxide dismutase (SOD) were measured by biochemical methods. RESULTS: IAA/HRP initiated growth inhibition of BXPC-3 cells in a dose- and time-dependent manner. Flow cytometry revealed that the cells treated for 48 h were arrested at G1/G0. After exposure to 80 micromol/L IAA plus 1.2 microg/mL HRP for 72 h, the apoptosis rate increased to 72.5 per thousand, which was nine times that of control. Content of MDA and activity of SOD increased respectively after treatment compared to control. Meanwhile, IAA/HRP stimulated the formation of free radicals. CONCLUSION: The combination of IAA and HRP can inhibit the growth of human pancreatic cancer BXPC-3 cells in vitro by inducing apoptosis.

Genome comparison of a novel foot-and-mouth disease virus with other FMDV strains.

The genome of a novel foot-and-mouth disease virus, HKN/2002, was 8104 nucleotides (nt) in length (excluding the poly(C) tract and poly(A) tail) and was composed of a 1042-nt 5'-untranslated region (UTR), a 6966-nt open reading frame, and a 93-nt 3'-UTR. Genome sequences of HKN/2002 and other known FMDV strains were compared. The VP1, VP2, and VP3-based neighbor-joining (NJ) trees were divided into distinct clusters according to different serotypes, while other region-based NJ trees exhibited some degree of intercross among serotypes. Mutations in HKN/2002 were revealed, including frequent deletions and insertions in the G-H loop of VP1, and deletion involving 10 amino acid residues in the 3A protein. An evolutionary relationship of HKN/2002 with an Asian FMDV lineage isolated from a Hong Kong swine host in 1970 was postulated. A 43-nt deletion identified in the 5'-UTR of HKN/2002 possibly contributed to the loss of one pseudo-knot domain.

[Analysis of the main amatoxins and phallotoxins in Amanita exitialis--a new species in China].

The content and distribution of the main Amatoxins (alpha-amanitin, beta-amanitin) and Phallotoxins (Phallacidin, Phallisin, Phalloin, Phalloidin) in the three tissues (cap, stipe and volva) of Amanita exitialis were evaluated by means of high-performance liquid chromatography. The results showed that Amanita exitialis was a lethal mushrooms, the cap had the highest content of total toxins, it reached 8152.6 microg/g dry weight, the toxins content in stipe reached 3742.3 microg/g dry weight, whereas the volva had the lowest content of total toxins,it had only 1142.5 microg/g dry weight. The distribution of Amatoxins and Phallotoxins in the tissues were revealed and it displayed that the content of Amatoxins (alpha-amanitin and beta-amanitins especially alpha-amanitin) in the cap, stipe or volva of A. exitialis was higher than that of Phallotoxins (Phallacidin, Phallisin, Phalloidin and Phalloin). But the content of Phallotoxins especially Phallacidin was gradationally higher from cap to stipe and to volva.