Modification of carbon nanofibers for boosting oxygen electrocatalysis.

Oxygen electrocatalysis is a key process for many effective energy conversion techniques, which requires the development of high-performance electrocatalysts. Carbon nanofibers featuring good electronic conductivity, large specific surface area, high axial strength and modulus, and good resistance toward harsh environments have thus been recognized as reinforcements in oxygen electrocatalysis. This review summarizes the recent progress on carbon nanofibers as electrocatalysts for oxygen electrocatalysis, with special focus on the modulation of carbon nanofibers for further elevating their electrocatalytic performance, which includes morphological and structural engineering, surface and pore size distribution, defect engineering, and coupling with other electroactive materials. Additionally, the correlation between the geometrical/electronic structure of their active centers and electrocatalytic activity is systematically discussed. Finally, conclusions and perspectives of this interesting research field are presented, which we hope will provide guidance for the future fabrication of more advanced carbon-fiber-based electrocatalysts.

Associations between Personal PM2.5 Elemental Constituents and Decline of Kidney Function in Older Individuals: the China BAPE Study.

Long-term exposure to fine particulate matter (PM2.5) is associated with kidney dysfunction. However, few studies have investigated acute effects of PM2.5 elemental constituents on renal function. We evaluated associations between personal PM2.5 and its elemental constituents and kidney function, assessed by an estimated glomerular filtration rate (eGFR) in Biomarkers of Air Pollutants Exposure in the Chinese aged 60-69 study. Seventy one older individuals were visited monthly between September 2018 and January 2019. Each participant wore a PM2.5 monitor for 72 h, responded to a questionnaire, and underwent a physical examination with blood sampling. Linear mixed-effect models were used to estimate associations between personal PM2.5 elemental constituents and eGFR. We found that significant changes in eGFR from -1.69% [95% confidence interval (CI): -3.34%, -0.01%] to -3.27% (95% CI: -5.04%, -1.47%) were associated with interquartile range (IQR) increases in individual PM2.5 exposures at various lag periods (7-12, 13-24, 0-24, 25-48, and 49-72 h). An IQR increase in 72 h moving averages of copper, manganese, and titanium in personal PM2.5 corresponded to -2.34% (95% CI: -3.67%, -0.99%) to -4.56% (95% CI: -7.04%, -2.00%) changes in eGFR. Personal PM2.5 and some of its elemental constituents are inversely associated with eGFR in older individuals.

[Determination of four bisphenolic compounds in drinking water by liquid chromatography-tandem mass spectrometry].

OBJECTIVE: To simultaneously determine the four bisphenolic compounds (bisphenol F, bisphenol A, tetrachlorobisphenol A and tetrabromobisphenol A) in drinking water by liquid chromatography tandem mass spectrometry. METHODS: 200 ml water sample was extracted by solid-phase extraction, eluted with methanol and analyzed by liquid chromatography tandem mass spectrometry under the MRM mode. The separation was carried out on a T3 column (2.1 mm x 150 mm, 3 µm). RESULTS: The limits of detection for the four bisphenolic compounds were in the range of 0.20 - 5.5 ng/L. The mean recoveries at the two spiked levels were 87.1% - 109.0% with the intra-day precision between 6.3% - 12.4% and inter-day precision between 4.5% - 15.4%. The method was applied for determination of 15 water samples. CONCLUSION: The method was sensitive, precise and accurate.

A novel oxy-oxonia(azonia)-cope reaction: serendipitous discovery and its application to the synthesis of macrocyclic musks.

This brief review, including new experimental results, is the summary of a talk at the GDCh conference 'flavors & fragrances 2013' in Leipzig, Germany, 11th-13th September, 2013. Musk odorants are indispensable in perfumery to lend sensuality to fine fragrances, a nourishing effect to cosmetics, and a comforting feeling to laundry. We have recently found serendipitously a new oxy-oxonia-Cope rearrangement. In this account, we review the background of oxonia-sigmatropic rearrangements and the discovery of this novel reaction. Special attention is focused on the versatile lactone and lactam formation reactions via [n+4] ring enlargement and the macrocyclization in the synthesis of new macrocyclic musks. The synthesized structures provide new insights into the structure-odor relationships of musks.

[Determination of S-phenylmercapturic acid in urine by on-line enrichment liquid chromatography tandem mass spectrometry].

OBJECTIVE: To develop on-line enrichment liquid chromatography tandem mass (LC-MS/MS) method for determination of S-phenylmercapturic acid (S-PMA) in urine. METHODS: With d2-S-PMA added as internal standard, the urine samples were cleaned up and concentrated on Hypersil GOLD (20 mm x 2.1 mm x 12.0 microm) columns, and the targeted compounds were analyzed by HPLC-MS/MS under negative ion mode using Hypersil GOLD (50 mm x 2.1 mm x 3.0 microm) columns as analyzed columns. In the process of enrichment, the mobile phase is CH3OH: HCOOH (0.2%) = 5:95 (volume ratio), the flow rate is 1.50 ml/min. During the analysis, the mobile phase is CH3CN and HCOOH (0.2%) gradient elution, the flow rate is 350 microl/min. RESULTS: The linear range was 0-500 ng/ml. The related coefficient was 0.9986. The detection limit was 8.0 ng/ml. The recoveries were 78.2%-84.5%. The relative standard deviation was 1.49% (n = 5). CONCLUSION: The method uses internal standard method, it was used for determination of S-phenylmercapturic acid in the urine, sample don't need too much pretreatment, the sample volume to reduce, the organic solvent volume decrease. The method was simple, rapid, sensitive and accurate. It was for the detecting for S-phenylmercapturic acid in urine.

Single-atom catalysts for catalytic benzene oxidation to phenol: recent progress and future perspectives.

Single-atom catalysts (SACs), affording 100% metal dispersion and maximized metal atom utilization, have recently emerged as a new type of potential catalyst for catalytic reactions, particularly for benzene oxidation to phenol. Their great advantages have stimulated researchers' intensive endeavors toward the development of highly efficient SACs, and various metal SACs are well fabricated for facilitating the catalytic benzene oxidation reaction. Aiming to gain a better understanding of the research progress in SACs for boosting benzene oxidation into phenol in recent years, we herein present a comprehensive review with a particular focus on the roles of metal atoms and supports when used for the catalytic oxidation reactions. Additionally, the applications of many advanced SACs in benzene oxidation reactions and their structure-activity correlation are presented, which include noble-metal SACs and non-noble-metal SACs. Finally, challenges remaining in this research area are discussed and possible future research directions are proposed.

Association between Organophosphate Ester Exposure and Insulin Resistance with Glycometabolic Disorders among Older Chinese Adults 60-69 Years of Age: Evidence from the China BAPE Study.

BACKGROUND: Organophosphate esters (OPEs) are common endocrine-disrupting chemicals, and OPE exposure may be associated with type 2 diabetes (T2D). However, greater knowledge regarding the biomolecular intermediators underlying the impact of OPEs on T2D in humans are needed to understand biological etiology. OBJECTIVES: We explored the associations between OPE exposure and glycometabolic markers among older Chinese adults 60-69 years of age to elucidate the underlying mechanisms using a multi-omics approach. METHODS: This was a longitudinal panel study comprising 76 healthy participants 60-69 years of age who lived in Jinan city of northern China. The study was conducted once every month for 5 months, from September 2018 to January 2019. We measured a total of 17 OPEs in the blood, 11 OPE metabolites in urine, and 4 glycometabolic markers (fasting plasma glucose, glycated serum protein, fasting insulin, and homeostatic model assessment for insulin resistance). The blood transcriptome and serum/urine metabolome were also evaluated. The associations between individual OPEs and glycometabolic markers were explored. An adverse outcome pathway (AOP) was established to determine the biomolecules mediating the associations. RESULTS: Exposure to five OPEs and OPE metabolites (trimethylolpropane phosphate, triphenyl phosphate, tri-iso-butyl phosphate, dibutyl phosphate, and diphenyl phosphate) was associated with increased levels of glycometabolic markers. The mixture effect analysis further indicated the adverse effect of OPE mixtures. Multi-omics analyses revealed that the endogenous changes in the transcriptional and metabolic levels were associated with OPE exposure. The putative AOPs model suggested that triggers of molecular initiation events (e.g., insulin receptor and glucose transporter type 4) with subsequent key events, including disruptions in signal transduction pathways (e.g., phosphatidylinositol 3-kinase/protein kinase B and insulin secretion signaling) and biological functions (glucose uptake and insulin secretion), may constitute the diabetogenic effects of OPEs. DISCUSSION: OPEs are associated with the elevated risk of T2D among older Chinese adults 60-69 years of age. Implementing OPE exposure reduction strategies may help reduce the T2D burden among these individuals, if the relationship is causal. https://doi.org/10.1289/EHP11896.

[Determination of nine kinds of polycyclic aromatic hydrocarbons in serum by high performance liquid chromatography].

OBJECTIVE: To develop a high performance liquid chromatography (LC) method for simultaneously determination of polycyclic aromatic hydrocarbons (PAHs) in serum. METHODS: PAHs could be separated completely by using C18 column and detected by fluorescence detector at wavelengths (Ex = 340 nm, Em = 425 nm). The mobile phase A was acetonitrile and mobile phase B was water with a flow rate at 1.0 ml/min. RESULTS: The concentration of PAHs achieved a good linear relation with the peak area. The correlation coefficient was in the range of 0.9941-0.9999. The recoveries were in the range of 91.4%-99.8% and the RSD were in the range of 2.56%-12.7%. The detection limits were in the range of 0.05-0.10 ng/ml. CONCLUSION: The method was simple, rapid, sensitive and accurate, and suitable for the detection of PAHs in serum.

[Simultaneous determination of six antibiotics in disinfection products by high performance liquid chromatography tandem mass spectrometry].

OBJECTIVE: To develop a method for determination of the Metronidazole, Chlortetracycline hydrochloride, Oxytetracycline dihydrate, Minocycline hydrochloride, Erythromycin and Tetracycline hydrochloride in disinfection products by high performance liquid chromatography tandem mass spectrometry(LC-MS/MS). METHODS: Samples were extracted by methanol and filtered through 0.45 microm PTFE membrane filter, then analyzed by LC-MS/MS using Waters Symmetry C18 (2.1 mm x 150 mm, 3.5 microm) column in positive ion scan mode. The mobile phase was 5 mmol/L ammonium acetate, methanol and acetonitrile. RESULTS: The linear range was 0-2000 ng/ml and the correlation coefficients were more than 0.998, the average recoveries ranged from 74.7% to 114% with the relative standard deviations between 1.6%-20.2%. The method was successfully used to detect the content of antibiotics in 115 disinfection products. CONCLUSION: The method is simple, sensitive, selective and suitable for the analysis of residual content of antibiotics in cream formulations of disinfection products.

[Simultaneous determination of 11 phthalate metabolites in urine by liquid chromatography tandem mass spectrometry].

OBJECTIVE: To develop a method for determining 11 kinds of phthalate metabolites in urine simultaneously. METHODS: The phthalate metabolites in human urine samples were hydrolyzed by glucuronidase, and then were concentrated by solid-phase extraction and eluted by methanol/acetonitrile (1 : 1, V/V). After chromatographic separation on phenyl column, the analytes were analyzed qualitatively and quantitatively under MRM mode. RESULTS: The limits of detection (LOD) for the eleven kinds of phthalate metabolites were in the range of 0.13 - 2.27 ng/ml. The mean recoveries at the two spiked levels were 67% - 108%, with the relative standard deviation (RSD) of less than 12%. CONCLUSION: The method can be used to determine the residues of eleven kinds of phthalate metabolites in urine accurately and sensitively.

[Influence of PAHs exposure and GSTT1, GSTM1 genotypes on urinary 1-OHP as exposure biomarker].

OBJECTIVE: To study the influence of polycyclic aromatic hydrocarbons (PAHs) exposure (ambient concentration and smoking) and GSTT1, GSTM1, genotypes on urinary 1-OHP as exposure biomarker. METHODS: 51 Cops who working outside were selected as study group, 48 Cops who working in office were selected as control Group. The ambient concentrations of PAHs both of two circumstances and the urinary 1-OHP of subjects were measured. The ambient concentrations of PAHs and the urinary 1-OHP were determined by high performance liquid chromatography (HPLC). The GSTT1, GSTM1 genotypes were determined by PCR. RESULTS: The ambient concentrations of PAHs in the study group and the control group were 20.85 ng/m3 and 12.79 ng/m3 respectively. There were not significant difference in urinary 1-OHP among the persons who had the deference GSTT1, GSTM1, genotypes and the same smoking habits in the study group and the control group. The urinary 1-OHP concentrations of the study group were higher than those of the control group when they had the same genotypes for non-smokers. Smoking stratified analysis showed that urinary 1-OHP concentrations of smokers were higher than those of non-smokers, the urinary 1-OHP concentrations of smokers in control group were higher than those of the non-smokers in study group. CONCLUSION: The ambient PAHs concentration and smoking could be the important factors generated the urinary 1-OHP concentration. While the levels of ambient PAHs were low, the smoking could change more prominent. The GSTT1, GSTM1 genotypes could not be the major influential factors.

[Relationship of PAHs levels in umbilical cord blood and the PAHs exposure between the mother and the paired newborns].

OBJECTIVE: To determinate the present polycyclic aromatic hydrocarbons (PAHs) levels in cord blood in order to discuss the PAHs exposure relationships between mother and paired newborns. METHODS: 347 pregnant women joined the study and the information of the 271 paired mother-newborns were used to analysis the exposure relationship. Questionnaire and bio-samples were got during the period of October 2006 to January 2008. High-performance liquid chromatography (HPLC) was used to determine the PAHs (7 kinds) levels in cord blood and maternal blood. RESULTS: In the 271 paired mother/newborns, several kinds of PAHs were detected in nearly all the serum of the subjects. The serum concentrations of B(k)F, B(a)P and DB(a, h) A in cord blood were significantly higher than those in paired maternal blood. In addition, the serum concentrations of B(b)F in cord blood was higher than that in maternal blood (P > 0.05). CONCLUSION: There are several kinds of PAHs detected in the umbilical cord blood and the PAHs levels in cord blood is the same as or even higher than that in the maternal blood, which means that could be is very important to develop the prenatal exposure assessment.

[Determination of bisphenol A in drinking water system components by liquid chromatography-tandem mass spectrometry].

OBJECTIVE: To develope the determination methods for bisphenol A in drinking water system components. METHODS: 30 samples were quantitatively analyzed by liquid chromatography-tandem mass spectrometry (LC/MS/MS). RESULTS: Bisphenol A was linear in the range 0-100 ng/ml and the linear correlation coefficient reached 0.9994. The minimum detection limit was 5 microg/kg. The spiked recoveries were from 90% to 99%, and the RSD were between 1.8 -5.0%. Bisphenol A was measured in nine out of thirty samples. The detected ratio was 30% and the maximum was 1.82 mg/kg. CONCLUSION: The method was quick, sensitive and specific.

[Effect of nitrogen and phosphorous on the production of microcystin under laboratory conditions].

OBJECTIVE: To explore the effect of phosphorus, nitrogen on the production of microcystin under specific laboratory condition. METHODS: The microcystis were ampliatively cultured for three times in N and P free culture. Then the microcysitis were inoculated in the culture at the concentrations of 0, 0.5, 1.0, 5.0 and 10.0 mg/L P for 20 days. The microcystis were inoculated in the BG-11 cultures at the concentrations of 0.05 mg/L and 5.0 mg/L P, NaNO3 were added in the culture according to the mol ratios of N/P were 5:1, 10:1, 20:1, 50:1, 100:1 and were cultured for 20 days. The changes of the count of the microcystis were observed. The microcystis cell were breaked at the 8th, 12th, 16th and 20th days after the beginning of culturing, the the microcystin were extracted and detected by HPLC. RESULTS: When the concentrations of phosphorus were lower than 5.0 mg/L, The productions of microcystin increased with the phosphorus concentrations. But when the concentrations of phosphorus were 10.0 mg/L, the productions of microcystin significantly decreased. In the culture at the concentrations of 0.05 mg/L P, the microcystin concentration per cell (MCYST fg/cell) and the microcystin concentrations per milliliter (MCYST microg/ml culture) presented the greatest value when the N/P ratio was 50:1. But, In the culture at the concentrations of 5.0 mg/L P, the microcystin concentrations per cell (MCYST fg/cell) and the microcystin concentrations per milliliter (MCYST microg/ml culture) presented the greatest value when the N/P ratio was 20:1. CONCLUSION: P concentrations significantly incluence the production of microcystin. The P concentrations in water should be controlled through different way to control the production of microcystins.

A pilot study on using urinary 1-hydroxypyrene biomarker for exposure to PAHs in Beijing.

To study whether the urinary 1-hydroxypyrene (1-OHP) could be the biomarker of atmospheric PAHs, a small-scale pilot study was carried out on the relation of 1-OHP vs PAHs with the traffic policemen in Beijing of smokers and nonsmokers to be subgroups in both the exposure and control groups. Both the PAHs and 1-OHP were analyzed with high performance liquid chromatography (HPLC). The ambient concentrations of PAHs were different at the different sites (the average sum of PAHs (TPAH) were 12.36, 16.27, 18.37 ng/m(3) at the suburban residential, police station and high traffic area, respectively.), but considerably lower than the personal-exposure concentrations (the average TPAH were 65.84 and 47.28 ng/m(3) for patrol cars and inspection station, respectively). Pyrene was correlated well with BaP and the summed PAHs (TPAH), with the correlation coefficients (R) of 0.79, 0.87 for ambient level and 0.92, 0.96 for personal exposure, respectively. The average of 1-hydroxypyrene of smokers and nonsmokers were 0.39, 0.15 mumol/mol creatinine in control group and 0.57, 0.33 mumol/mol creatinine in exposure group, respectively. The better correlation of pyrene to BaP and TPAH especially for personal exposure samples indicated that the probability of urinary 1-hydroxypyrene, the metabolite of pyrene, to be the biomarker of total PAH. Nonsmokers in the exposure and control groups had indistinguishable levels of 1-OHP, presumably because the ambient levels of pyrene were so similar (the average were 3.25, 3.20 ng/m(3) at the police station and high traffic area, respectively.). Smokers in the control group had significantly higher 1-OHP than that of the nonsmokers, but showed indistinguishable differences in the exposure group. These results suggested that urinary 1-OHP could be a biomarker of PAHs only when the level of PAHs was at a relatively higher level. Smoking as an important influencing factor need to be controlled carefully.