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Efficient and long-term photoelectrochemical (PEC) hydrogen liberation from hydrazine hydrate was achieved using CdS nanorod arrays (CdS NRs) as the photoelectrode. Under light irradiation, the CdS photoelectrode exhibited high efficiency and stability for the anodic oxidation of N2H4·H2O with high selectivity for hydrogen production at the counter cathode. The yield and Faradic efficiencies (FE) of hydrogen from N2H4·H2O solution under mild conditions were determined to be 658 μmol/cm2 and 90%, respectively, after 5 h of operation. The photocurrent density of the CdS electrode in electrolyte with N2H4·H2O reached 7.6 mA/cm2 at 1.23 V versus RHE, five times higher than that in N2H4·H2O free electrolyte. And the persistence of CdS electrodes in electrolytes with N2H4·H2O was more than 100 h, while in N2H4·H2O free electrolytes, it was less than 100 s. An obvious cathodic shift of the photocurrent onset potential of about 300 mV was also observed. Furthermore, the kinetics of PEC oxidation of N2H4·H2O were further tested. In addition, it is expected that this work may provide a strategy to stabilize other unstable photoelectrodes for a wide range of applications and supply a way to produce hydrogen by photoelectrochemical decomposition of N2H4·H2O. [ABSTRACT FROM AUTHOR]

Endoscopic photoacoustic tomography (EPAT) is a rapidly developing catheter-based imaging technique to provide cross-sectional images of anatomical, functional and molecular data of tubular objects. The scanning geometry of the ultrasonic detector is enclosed in the cavity resulting in highly restricted acquisition of photoacoustically induced acoustic pressures. Thus, data-incompleteness is an important factor that causes degradation of the image quality. This work presents a method to solve the acoustic inverse problem of EPAT from incomplete measurements associated with the image formation process. This method combines the traditional variational iteration with convolutional neural network (CNN), in which the forward operator and adjoint operator of imaging are excluded from the network training and are embedded into each layer of the structural unit. The gradient information is utilized to reduce the influence of incomplete measurements on the image quality. The network is trained unit by unit in an adaptive way to achieve fast convergence. Our numerical results conducted on various data sets showed that the trained network is robust to the sampling rate of the measured data. Also, it is able to provide a generalization that can work across various noise levels in the data. In addition, a robust peak signal-to-noise ratio (PSNR) and structural similarity (SSIM) improvement obtained in the reconstructed images has been demonstrated in comparison with conventional TR reconstruction, CS reconstruction and post-processing by U-net. [ABSTRACT FROM AUTHOR]

In order to better understand both the conceptual and operational aspects of bioaccessibility and phytobioavailability of PTMs (Co, Cr, Cu, Li, Mn, Ni, Pb, Zn) in different urban soils, a total of 30 soil samples from agricultural region, entertainment district, education area, traffic area, residential area and industrial area (IA) in Baoji urban city (NW China) were collected and the bioaccessibility and phytobioavailability were measured by multi-in vitro models of PBET, SBET, citric acid leaching and Tessier sequential extraction procedure, respectively. The suitable in vitro measurement of bioaccessibility and phytobioavailability for each PTM was selected and would be reliably applied for health risk assessment. The results indicated that the bioaccessibility and phytobioavailability for each PTM evaluated by in vitro models depended on PTM total concentration and anthropologic activity influence. The health risks associated with bioaccessibility of PTMs exposure showed that the carcinogenic and non-carcinogenic risks in all areas for children and adults were below the threshold or acceptable risk levels except lead exposure on children in IA, indicating there were more health risks to the children in than that in other functional areas. It was worth that the highest observation of Pb in IA would strongly correlate with lead–acid battery industries, which the emissions would influence on the occurrences of Pb distributing in the other functional areas, which were supported from the analysis results of XPS. Therefore, the continuous monitoring and attention to the health risk of inhabitants in different functional areas should be paid. [ABSTRACT FROM AUTHOR]

Utilization of microbes is one of the most promising methods to remediate potentially toxic metals (PTMs) from soil. In this study, a systematic investigation was conducted to study the influence of Bacillus subtilis on PTMs occurrence, fractionation, translocation, and accumulation in the rhizosphere soil of Maize (Zea mays L.) in pot experiments. B. subtilis showed strong effects on the fate and mobility of Pb, Sb, Ni, Zn, Cu, and Cr, and it also affected PTMs' distribution in the rhizosphere soil, maize growth, and microbial community structure. Results showed that it was easier for Zn to accumulate in maize roots than other PTMs. According to chemical fractionation, B. subtilis tended to immobilize Pb, Sb, Ni, Zn, and Cu in the rhizosphere soil. Compared with other PTMs, Cr tended to be more available and more mobile, which indicated a higher health risk to the eco-environment. These findings suggested that B. subtilis could be used as a geomicrobiological stabilizer to immobilize PTMs (Pb, Sb, Ni, Cu, Zn) in alkaline soils and decrease their uptake by plants, thus reducing the risks of a potential transfer into the food chain. [ABSTRACT FROM AUTHOR]

A total of 155 urban soil and 157 dust samples were collected from Xining city (NW, China) with the objective to systematically investigate the spatial occurrences, sources, and health risk status of potential toxic metals (PTMs) bound in urban soil and street dust. Results established by Geographic Information System tools with inverse distance weighted interpolation technique indicated that the spatial status of 24 multi-PTMs varied with their concentration levels in urban soils and street dusts in monitored local areas. However, they had the similar sources in soil and dust. It was found that Bi, Ga, Nb, Ni, Rb, Sr, Th, U, Y, Zr, As, Mn, Nb, Ti, and V would be possibly predominated by nature material, whereas contamination of Ba, Cr, Cu, Pb, and Zn was clearly related to traffic-related sources. Peculiar associations among Sb, Sn, Ce, and Co were possibly enriched in soil and dust very close to the industrial activities. It was noted that PTMs in urban soil was an important contributor to them in dust. Compared with the potential ecological risk index of all PTMs, Sb posed very high risk. The calculated hazard index and cancer risk of all PTMs suggested the acceptable range both to noncarcinogenic and carcinogenic risk to children and adults except for the case of Cr. However, the noncarcinogenic risk for children was usually higher compared with adults. Although the noncarcinogenic and carcinogenic risk were not significant, the risk of Cr above the threshold for children and adults were observed in most local sites, which should be given more attention. [ABSTRACT FROM AUTHOR]

In this paper, we reported a simple and effective strategy to synthesize core-shell dummy template magnetic molecularly imprinted polymers (FeO@DMIPs) using ethyl paraoxon as a template for the recognition and selective extraction of organophosphorus pesticide. Initially, monodisperse FeO nanoparticles were synthesized directly through a facile one-pot hydrothermal method. Then, the imprinted layer was synthesized directly on the surface of the magnetic core by means of a one-pot sol-gel copolymerization which avoided further modification of the external part of the magnetic core. The structure and morphology of the materials (FeO@DMIPs) were characterized by SEM, TEM, FTIR, XRD, and VSM. It was observed that FeO@DMIPs showed regular morphology, good dispersibility, and superparamagnetism. The synthesis conditions for the formation of FeO@DMIPs were systematically investigated. It was found that the morphology and monodispersity of FeO@DMIPs were highly influenced by the ratio of the mixture solvent of methanol and water and the volume ratio of functional monomer (APTES) and cross-linker (TEOS). The binding performance of the imprinted polymers was investigated through a series of adsorption experiments, which indicated that the FeO@DMIPs had a fast adsorption rate (15 min) and high adsorption capacity (195.7 mg g) to methyl parathion and phoxim. Meanwhile, real wine sample tests demonstrated a good extraction effect. This study provides a possibility for the selective extraction of organophosphorus pesticide residue in a complex matrix. [ABSTRACT FROM AUTHOR]

In this study, a core-shell magnetic dummy molecularly imprinted polymer (MDMIP) was prepared with a novel and simple method. The imprinting layer was synthesized directly on the surface of FeO by only one step, which avoided further modification on the exterior of magnetic core. 4,4′-Dihydroxybiphenyl (DDBP) was used as dummy template instead of bisphenol A (BPA) to eliminate the effect of template leakage on quantitative analysis. When used as solid-phase extraction sorbent, a rapid, sensitive, and accurate method for the simultaneous extraction, concentration, and determination of trace BPA in plastic bottled beverage samples by MDMIP-SPE coupled with high-performance liquid chromatography (HPLC) was developed. Advantages of such method may be counted as the mild working temperature during the synthesis, simplicity of extraction procedure, avoidance of leakage of template, time-saving, and high binding capacity and affinity. Several parameters affecting the extraction efficiency of the analytes including the sorbent mass, the pH of sample solution, the HAc percentage in the elute, and the desorption time were investigated. Under optimized conditions, the calibration graph was linear over the range of 11.4-4560 ng mL with the limit of detection of 0.083 ng L. In addition, the higher enrichment factors (400-fold) and good recoveries (88.6-99.5%) with relative standard deviation (RSD) values less than 9.5% were achieved. Moreover, the developed extraction protocol simplified the process of traditional solid-phase extraction (SPE) provided the possibility for separation and enrichment of BPA from complicated food matrices. [ABSTRACT FROM AUTHOR]

Atmospheric pollution from atmospheric particulate matter (APM) deposition is one of the major sources of potential hazardous elements (PHEs) contamination. In this study, 68 total APM samples were collected from the local areas of southern Xi'an (NW China) during the long-term period of the 2001-2012 dust campaign. The chemical fractionation of PHEs (Cr, Cu, Ba, Sr, As, Pb, and Zn), their contamination levels, and ecological health risk were examined. The mobility sequence based on the sums of the first three fractionations of the modified BCR (the European Community Bureau of Reference) sequential extraction stages was: Cu (77.83 %) > Pb (74.50 %) > Zn (55.40) > Sr (52.93) > Ba (40.89) > Cr (30.09) > As (21.59). The contamination levels of APMs from these sites, calculated from the total content indices ICF, were uniformly moderate in degree. The obtained single-metal model MI (speciation index) values had allowed for classification of elements as a function of their potential ecological risk as As (64.00 mean value) > Pb (43.86) > Sr (37.50) > Cu (11.53) ≅ Ba (11.32) > Zn (7.68) > Cr (1.88). The results presented that the toxic As posed a moderate to considerable risk; Pb and Sr varied from low to a moderate risk, while others posed low risk. However, a new developed multi-metal model GRI (speciation index) indicated that the PHEs in most of the APMs posed moderate ecological risk. The result was consistent with that of ICF indexes. Combined with the US Environmental Protection Agency, we developed models of (ingestion, dermal and inhalation) hazard index (HI), children's health risk due to PHEs exposure from APM was higher than that for adults. Much attention should be paid to the PHE As (HI = 0.864, close to 1) for children. While, carcinogenic risk for adults was higher than that for children. Although cancer risk because of As, Cr and Pb exposure were within an acceptable range, the PHEs exposed to the highest density of the population in residential and educational villages in south of Xi'an would be much more concerned. The moderate ecological risk and the higher risk for children's health illustrated that special attention has to be taken to the mentioned PHEs from APMs in the local ecosystem, and their health risk impact should continue to be checked carefully. The new developed GRI index method was to be useful for risk assessment of PHEs combining with their chemical fractionations. [ABSTRACT FROM AUTHOR]

Ag/SBA-15 catalysts have been prepared by means of in situ reduction methods using hexamethylenetetramine and formaldehyde as reducing agents, respectively, and characterized by N2 adsorption/desorption, XRD, TEM and XPS. Presence of nanoparticles of silver in SBA-15 were confirmed by high angle X-ray diffraction data (peaks between 2 θ = 35–80º) and XPS, and transmission electron microscopy confirmed the diameter of the nanoparticles. When hexamethylenetetramine was used as reducing agent, uniform Ag nanoparticles inside the channels were formed, and diameter of nanoparticles is found to be ~6.0 nm which is coincident with channel diameter of SBA-15. The catalysts were subjected to CO oxidation in a flow reactor at atmospheric pressure and temperatures up to 300 °C. Studies revealed that catalysts prepared with different reducing agents strongly influence their catalytic performance in the CO oxidation, what prepared with hexamethylenetetramine as mild reducing reagent shows a certain low temperature catalytic activity. [ABSTRACT FROM AUTHOR]

A sensitive method using capillary gas chromatography coupled with a micro electron capture detector (μECD) has been developed for the determination of cyanide in cigarette smoke. The procedure is based upon the conversion of cyanide to cyanogen chloride by chloramine-T. Cyanogen chloride, dissolved in n-hexane, was analyzed by GC–μECD. Under optimum conditions, the detector response was linear from 25.0 ng mL−1 to 15.0 μg mL−1 with relative standard deviation between 0.07 and 3.30%. Recovery ranged from 86.0 to 116.0%. The method was shown to be precise, accurate and linear over the range of concentration of analytes. [ABSTRACT FROM AUTHOR]