Jianzhang Fang

Trace elements are associated with urinary 8-hydroxy-2′-deoxyguanosine level: a case study of college students in Guangzhou, China

Many trace heavy elements are carcinogenic and increase the incidence of cancer. However, a comprehensive study of the correlation between multiple trace elements and DNA oxidative damage is still lacking. The aim of this study is to investigate the relationships between the body burden of multiple trace elements and DNA oxidative stress in college students in Guangzhou, China. Seventeen trace elements in urine samples were determined by inductively coupled plasma-mass spectrometry (ICP-MS). Urinary 8-hydroxy-2′-deoxyguanosine (8-OHdG), a biomarker of DNA oxidative stress, was also measured using liquid chromatography tandem mass spectrometer (LC-MS/MS). The concentrations of six essential elements including manganese (Mn), copper (Cu), nickel (Ni), selenium (Se), strontium (Sr), and molybdenum (Mo), and five non-essential elements including arsenic (As), cadmium (Cd), aluminum (Al), stibium (Sb), and thallium (Tl), were found to be significantly correlated with urinary 8-OHdG levels. Moreover, urinary levels of Ni, Se, Mo, As, Sr, and Tl were strongly significantly correlated with 8-OHdG (P < 0.01) concentration. Environmental exposure and dietary intake of these trace elements may play important roles in DNA oxidative damage in the population of Guangzhou, China.

Urinary metabolites of organophosphate esters in children in South China: Concentrations, profiles and estimated daily intake

Organophosphate esters (OPEs) are widely used in household products as flame retardants or plasticizers and have become ubiquitous pollutants in environmental media. However, little is known about OPE metabolites in humans, especially in children. In this study, eight OPE metabolites were measured in 411 urine samples collected from 6 to 14-year-old children in South China. Bis(2-chloroethyl) phosphate (BCEP), bis(1-chloro-2-propyl) phosphate (BCIPP) and diphenyl phosphate (DPHP) were the dominant OPE metabolites, and their median concentrations were 1.04, 0.15 and 0.28 μg/L, respectively. The levels of urinary OPE metabolites in the present study were much lower than those in participants from other countries, with the exception of BCEP, suggesting widespread exposure to tris(2-chlorethyl) phosphate (TCEP, the parent chemical of BCEP) in South China. No significant difference in the concentrations of any of the OPE metabolites was observed between males and females (p > .05). Significant negative correlations were observed between age and BCEP, BCIPP, bis(1,3-dichloro-2-propyl) phosphate (BDCIPP), di-o-cresyl phosphate (DoCP) and di-p-cresyl phosphate (DpCP) (DCP), or DPHP (p < .05). Pearson correlation coefficients between urinary OPE metabolites indicated multiple sources and OPE exposure pathways in children. The estimated daily intake suggested that children in South China have a relatively high exposure level to TCEP. To the best of our knowledge, this is the first study to report the urinary levels of OPE metabolites in Chinese children.

Plasmonic Ag-pillared rectorite as catalyst for degradation of 2,4-DCP in the H2O2-containing system under visible light irradiation.

This study aims at photocatalytic degradation of 2,4-DCP with the assistance of H2O2 in aqueous solution by a composite catalyst of Ag-rectorite. The catalysts were prepared via a novel thermal decomposition method followed after the cation-exchange process. The synthesized nano-materials were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Brunauer-Emmett-Teller (BET) surface analyzer, Ultraviolet-visible light (UV-vis) absorption spectra, field-emission scanning electron microscope (FE-SEM) and transmission electron microscope (TEM). The different mechanisms of degradation process with or without visible light irradiation were discussed, respectively. Moreover, the degradation efficiency of 2,4-DCP wastewater under Ag-rectorite/H2O2/visible light system was investigated by series of experiments, concerning on effects of major operation factors, such as H2O2 dosage and the initial pH value. The highest degradation rate was observed when adding 0.18 mL H2O2 into 50 mL 2,4-DCP solution, and the optimal pH value was 4 for the reaction. Afterwards, total organic carbon (TOC) experiments were carried out to evaluate the mineralization ratio of 2,4-DCP.

Urinary bisphenol analogues and triclosan in children from south China and implications for human exposure

Bisphenols and triclosan (TCS) are widely used in consumer products. However, knowledge on human exposure to these anthropogenic chemicals has remained limited in China, especially for children. In this study, concentrations of seven bisphenols and TCS were determined in 283 urine samples collected from South China children aged between 3 and 11 years old. Bisphenol A (BPA), bisphenol S (BPS) and TCS were frequently detected in urine samples, with a detection rate of 93%, 89%, and 95%, respectively. Urinary concentrations of Σ7BPs (the sum concentrations of the seven bisphenols) ranged from 0.43 to 31.5 μg/L, with a median value of 0.91 μg/L, while TCS concentrations ranged from < limit of quantification to 21.9 μg/L (median: 0.21 μg/L). BPA was the predominant analogue (median: 0.35 μg/L), accounting for 49.8% of Σ7BPs. The urinary BPA concentrations in children from Guangzhou were significantly greater than those from Shenzhen. Correlation analysis suggested that multiple exposure sources to South China children likely existed for BPA, BPS, and TCS. Age, but not gender, was negatively associated with urinary residues of BPA and BPS (p < 0.05) and positively with TCS concentrations (p < 0.05). The estimated daily intake of Σ7BPs (23.9 ng/kg bw/day) or TCS (5.63 ng/kg bw/day) was below the tolerant reference dose of BPA, indicating no considerable health hazard to South China children.

Hydrothermal synthesis of a Ba and Mg co-doped Bi12GeO20 photocatalyst with enhanced visible light catalytic activity

Visible-light-activated (Ba,Mg)-codoped Bi12GeO20 has been successfully synthesized through a one-step hydrothermal method. The as-prepared samples were characterized by X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), UV-vis diffuse reflectance spectra (DRS) and photoluminescence spectroscopy (PL). XPS study suggests that barium and magnesium were introduced into the Bi12GeO20 crystal successfully. The band gap of (Ba,Mg)-codoped Bi12GeO20 was greatly reduced in comparison with the pure and single-doped Bi12GeO20. (Ba,Mg)-codoped Bi12GeO20 showed higher photocatalytic activity than pure Bi12GeO20 and single-doped Bi12GeO20 in the photodegradation of Rhodamine B (RhB) aqueous solution under visible light irradiation. Photogenerated holes were the dominating active species, with the secondary and minor factors of hydroxyl radical and superoxide radical in the photodegradation process of (Ba,Mg)-codoped Bi12GeO20. For three cycles, the co-doped Bi12GeO20 exhibited high stability.

Improved Photodegradation Efficiency of 2,4-DCP Through a Combined Q 3 Fe(III)-Decorated Porous g-C 3 N 4 /H 2 O 2 System

Graphitic carbon nitride (g-C3N4) is a photocatalyst with wide application in removal of organic pollutants. In this study, we designed a porous g-C3N4 (p-g-C3N4)/8-quinolinolato iron(III) (Q3Fe)/H2O2 system to enhance the organic pollutant removal efficiency by combining photocatalysis and Fenton interaction under neutral condition. The p-g-C3N4 was prepared through a two-step thermal oxidation reaction. Afterwards, Q3Fe-coupled p-g-C3N4 was prepared by an impregnating method. The 2,4-dichlorophenol (2,4-DCP) photodegradation ratio and decomposition rate of the p-g-C3N4/Q3Fe/H2O2 system are approximately 5 and 18 times as high as those of individual p-g-C3N4 system, respectively. Besides, its degradation rate is 4.3 times as high as that in the p-g-C3N4/H2O2 system. Meanwhile, Q3Fe/g-C3N4 also exhibits higher activity than individual p-g-C3N4 in 2,4-DCP photo-decomposing. On the basis of the results of the radical trapping experiments and the Fe(II) concentration in different systems, the synergistic effect between photocatalysis and Fenton reaction is vital for the efficient pollutant degradation. The coupled system combining p-g-C3N4 with Q3Fe and H2O2 shows potential for efficient treatment of recalcitrant organic pollutants. The combined system in this work indicated a new idea for the decomposition of organic pollutants.

Efficient visible-light-driven hydrogen evolution and Cr(VI) reduction over porous P and Mo co-doped g-C3N4 with feeble N vacancies photocatalyst

Developing highly efficient and inexpensive photocatalysts without noble metals, yet remarkably enhancing hydrogen production and Cr(VI) reduction activity, is highly needed. Here, the effective photocatalytic H2 evolution under visible light from an Eosin Y (EY)-sensitized (P, Mo)-g-C3Nx system by avoiding any noble metal co-catalyst is reported by the first time. Meanwhile, the optimized sample also displays the excellent performance in photocatalytic hexavalent chromium (Cr(VI)) reduction. In addition, this composite exhibits delectable stability for photocatalytic activities, no significant decay of activity is being observed after 16h reaction for photocatalytic H2 evolution (8h for Cr(VI) reduction). It is believed that this work will open up a new route for fabricating high-performance and inexpensive photocatalysts for hydrogen production and Cr(VI) reduction.