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Mercury (Hg) pollution is a worldwide concern. Silica nanoparticles (nano-SiO2) can be released into ecosystems through natural and anthropogenic (engineered nano-SiO2) processes. Here, the influence of two sizes (30 nm and 50 nm) of artificial nano-SiO2 on Hg accumulation in soybean plants, the chemical form and distribution of Hg in plant tissues and the levels of chlorophyll and antioxidant enzymes in plants were investigated. The results showed that both sizes of nano-SiO2 amendments alleviated the growth inhibition induced by Hg and reduced the accumulation (62.2–83.6% in roots; 67.9–75.7% in stems; 45.0–70.7% in leaves lower with nano-SiO2 amendments vs. Hg-only exposure) and translocation (transport rates: 0.18–0.19 with nano-SiO2 amendments vs. 0.22–0.26 Hg-only exposure) of Hg in soybean seedlings. Compared with the Hg-only exposed groups, nano-SiO2 amendments significantly reduced the Hg concentrations in the epidermis and pericycle of the roots and stems, especially the pericycle measured by synchrotron radiation X-ray fluorescence (SRXRF). The application of nano-SiO2 also ameliorated the chlorophyll decrease (15.3–50.1% higher with nano-SiO2 amendments vs. Hg-only exposure) and antioxidant enzyme increase (20.7–33.2% lower with nano-SiO2 amendments vs. Hg-only exposure) induced by Hg stress. Additionally, the RS–Hg–SR bonding form in the roots of nano-SiO2 treated groups significantly decreased when compared with that of Hg-only exposed groups, and over 85% of the total Hg content was present in the form of R–Hg–Cl, which was largely consistent with the original Hg exposure species and indicated a low incorporation rate of Hg into plant tissues. This study explored the mechanism of nano-SiO2 against Hg toxicity in plants, and offered a new passivating agent option for Hg remediation.

In mining areas, nano-sized elemental selenium (SeNPs), naturally produced through reduction of SeO32− by abiotic and biotic processes, usually co-exists with Hg in the environment. Little is known about the fate of SeNPs and how they affect the bioavailability and toxicity of Hg towards plants. In this study, the fate of SeNPs and Hg, and the effect of SeNPs on the mobilization of Hg in a hydroponic-cultured plant were investigated. It was found that SeNPs were less phytotoxic and had stronger capacity for Hg sequestration than SeO32−and SeO42−. Synchrotron radiation X-ray fluorescence (SR-XRF) and X-ray absorption near edge structure (XANES) spectroscopy revealed that SeNPs largely captured Hg2+via forming HgSe and HgSeNPs to prevent Hg2+ from entering the root stele, thus inhibiting translocation and accumulation of Hg in the aerial parts. Apart from immobilizing Hg, SeNPs also promoted the conversion of Hg2+ to less toxic RS–Hg–SR and R–Hg–R binding forms in plants. Meanwhile, a portion of SeNPs was transformed into SeMet stored as the nutrient Se source in plant tissues. This study provides insights into the reaction and fate of SeNPs and Hg in water-plant systems, which implies the significance of SeNPs in modulating the fate and toxicity of Hg in mining areas.

Mercury sulfide (HgS) constitutes the largest Hg reservoir in the lithosphere but has long been considered to be not bioavailable and a minor participant in Hg biogeochemical cycling. Herein, we report that bulk α-HgS can be dissolved and methylated in paddy soils, especially with rice culture. Bulk α-HgS exposure did not affect rice growth compared to the control group but significantly increased methylmercury (MeHg) contents in the rhizospheric soils (e.g., 80.15% and 108.71% higher for bulk α-HgS treatment vs. control at the seedling and maturation stages, respectively). Moreover, bulk α-HgS exposure induced an apparent accumulation of MeHg (50% higher for bulk α-HgS treatment vs. control) and markedly elevated total Hg (THg) in rice grains. The presence of DOM and reduced sulfide in paddy soils was further evidenced to drive the mobilization and dissolution of bulk α-HgS, thereby resulting in THg and MeHg accumulation in rice grains. These findings highlight the bioavailability of HgS in rice paddies and suggest that bulk HgS should be considered when assessing Hg health risks and developing efficient remediation approaches in Hg-contaminated croplands.

Gasochromic based optical hydrogen sensors have attracted much attention as normal temperature sensors. The behaviors of the hydrogen diffusion largely affect the reaction process and the sensitivity. However, few researches focused on the influence of hydrogen diffusion in gasochromic films. Here, we report a method to pre-split the H2 molecule and separate the hydrogen molecule and hydrogen atom diffusion process by deposition of porous PdCl2/SiO2 catalyst films on WO3. The response time of WO3 at 844 Pa H2 partial pressure reduced from 800 s to 200 s. The stability of WO3 film was largely improved to be more than 160 cycling lifetime. A validation experiment was designed and proved the diffusion of the hydrogen atom and the two-step model of H2 reaction on WO3 films, on the basis of which the diffusion coefficient of the hydrogen atom has been estimated. Moreover, the PdCl2 doping SiO2 catalyst exhibits substrate versatility, which can also coat on the nano-structured WO3.

The antagonistic effect between mercury (Hg) and selenium (Se) is conclusively established in animals and human beings in the past decades. However, the underlying mechanisms of the interactions between Hg and Se in plants, as well as the metabolism of Hg-Se compounds in crops are still far from being understood. The botanic metallomics of Hg and Se mainly focuses on the translocation, transformation, and metabolism of Hg and Se in the environmental and botanic systems employing metallomics methods. An adequate understanding of the biological behavior of Hg and Se in plant is beneficial for sequestration of Hg and Se in soil-plant systems with high Hg and Se contamination. It can also provide a molecular mechanistic basis for Se supplementation in Se-deficient areas. Here, the key developments in current understanding of Hg and Se interactions in plants are reviewed. The metabolism and antagonism of Hg and Se in various plants, as well as the advanced analytical methods commonly used in this field, are summarized and discussed. As suggested, plant Hg and Se uptake, metabolism, and antagonism can be taken into account for detoxification and remediation strategies for the reduction of Hg and Se in the food chain.

Elevated methylmercury (MeHg) production in mining-contaminated paddy soils, despite the high fraction of refractory HgS(s), has been frequently reported, while the underlying mechanisms are not fully understood. Here, we hypothesized that sulfate input, via fertilization, rainfall, and irrigation, is critical in mobilizing refractory HgS(s) and thus enhancing Hg methylation in mining-contaminated paddy soils. To test this hypothesis, the effects of sulfate amendment on Hg methylation and MeHg bioaccumulation in mining-contaminated soil-rice systems were examined. The results indicated 28-61% higher net MeHg production in soils under sulfate amendment (50-1000 mg kg-1), which in turn increased grain MeHg levels by 22-55%. The enhancement of Hg methylation by Hg mobilization in sulfate-amended soils was supported by two observations: (1) the increased Hg(aq) release from HgS(s), the dominant Hg species in the paddy soils, in the presence of sulfide produced following sulfate reduction and (2) the decreases of refractory HgS(s) in soils under sulfate amendment. By contrast, changes in the abundances/activities of potential microbial Hg methylators in different Hg-contaminated soils were not significant following sulfate amendment. Our results highlight the importance to consider enhanced Hg mobility and thus methylation in soils under sulfate amendment.

Mercury (Hg) is a hazardous chemical in the environment and can accumulate in the food chain. Selenium (Se) is a necessary element for human health and has antagonistic effects on Hg toxicity. In this work, we investigated the effect of Se on Hg containing and Hg-responsive proteins in rice using 1, 2-dimensional electrophoresis combined with SR-XRF techniques. Two weeks old rice seedlings were exposed to Hg and/or Se compounds. After 21days proteins in the rice roots were separated by electrophoresis and their metal contents were determined by X-ray fluorescence to identify Hg and Se responsive biomolecules. The results show that under Hg stress alone Hg is bound to proteins with molecular weights of 15-25kDa. With the addition of Se, a new Hg-containing protein band in the 55-70kDa range was also found, while the content of Hg in the 15-25kDa proteins decreased. Ten and nine new protein spots were identified after adding Se to inorganic Hg and methylmercury exposed roots, respectively. Adding Se regulates the abundance of proteins associated with carbohydrate and energy metabolism, stress response, cell cycle, and DNA replication indicating that these proteins mediate the antagonism of Se against Hg toxicity. This study helps us to better understand the molecular mechanism of Hg tolerance as well as the molecular antagonism between Hg and Se in rice plants.

Acid mine drainage (AMD) is one of the most serious environmental problems and extreme environments on the earth, with high concentrations of sulphate and dissolved metals. A comprehensive description of dissolved organic matter (DOM) in these reservoirs is lacking, and it can play an important role in AMD pollution treatment and ecosystem. Thus, the source, composition and property of DOM in an AMD reservoir in Ma'an shan, China were studied using Fourier transform ion cyclotron resonance mass spectrometry and three-dimension excitation emission matrix fluorescence spectroscopy. The results suggested that the autochthonous algal metabolites significantly contributed to the DOM pool in the AMD reservoir. Bioavailable substances with lower oxidation, unsaturation and aromaticity such as lipids and carbohydrates were lacking in the AMD reservoir especially in the deeper layers. In addition, the proportion of sulfur compounds was significantly higher than that in other waters, suggesting the potential formation of organic matter with sulfur atom in a sulfur-rich environment. These findings underscore that the investigation of DOM in AMD reservoirs may offer references for the AMD treatment with addition of organic matter and broaden the understanding of special carbon cycling in the extreme environment of AMD.

Thiosulfate addition increases the solubility of mercury (Hg) in soil and Hg uptake by plants under oxic conditions. However, anoxic conditions could dominate the biogeochemical processes of Hg cycling during rice cultivation. The present study aimed to determine whether thiosulfate, a sulfur-containing fertilizer, could be used for Hg immobilization in paddy soil. A pot experiment was conducted using soil newly spiked with Hg and different doses of thiosulfate. Total Hg concentrations in rice tissues, Hg speciation in roots, and geochemical fraction of Hg in soils were investigated. Hydroponic cultivation was conducted to determine the subcellular distribution of Hg in root tissues. Thiosulfate application significantly reduced Hg concentration in rice plants. It increased the percentage of organic-bound Hg, but decreased the percentage of iron/manganese oxide-bound Hg. Thiosulfate enhanced iron plaque formation and Hg adsorption on the iron plaque. Its application increased the percentage of Hg forms similar to HgS and decreased those similar to Hg-glutathione [Hg(GS)2]. Thiosulfate amendments had a remarkable inhibitory effect on Hg accumulation in rice plants in newly Hg-spiked soil. This occurred because thiosulfate reduced Hg mobility in the rhizosphere and root tissues, promoted the formation of iron plaque, and facilitated more Hg adsorption by the iron plaque. Our findings suggest that appropriate thiosulfate treatment could be used as Hg-immobilizing agents in paddy soil.

Brassinosteroids (Brs) have drawn wide attention due to their protective role against toxicity of heavy metals in plants. To better understand the role of Br in arsenic (As) and cadmium (Cd) uptake by rice plants, a hydroponic experiment was conducted to investigate the combined effect of 24-epibrassinolide (Br24) or 28-homobrassinolide (Br28) and iron plaque (IP) on As and Cd uptake and accumulation in rice seedlings. Six-week-old seedlings were sprayed with 0.2 or 0.02 μM Br24 or Br28 and grown in nutrient solution for 3 d, and then 20 or 60 mg Fe2+ dm-3 (Fe20 and Fe60) was used to induce root IP formation for 3 d. These seedlings with or without Br and with or without IP were exposed to solution containing 0.5 mg dm-3 AsIII or Cd for 9 d. The results showed that rice growth decreased when Br24 were applied, but it increased when combination of Br24 and IP was applied. Fe concentrations in dithionite-citratebicarbonate (DCB) extracts were increased after 0.2 or 0.02 μM Br24 application in the absence of IP, but decreased by Br24 in the presence of IP. In the absence of IP, As and Cd content in leaves was significantly reduced by 0.02 μM Br24 and 0.2 μM Br28, respectively. The As content in leaves was also reduced by the combination of 0.02 and 0.2 μM Br28 and IP, and the Cd content in leaves was reduced by the combined effect of 0.2 μM Br24 and IP. These results indicate that Br24 and Br28 could impede As and Cd accumulation, and the interactions between Br and IP may have a potential in restricting the transport of As and Cd into rice shoots.

Screening for tolerant and high biomass producing plants is important for phytoextraction efforts in remediating agricultural soils contaminated by heavy metals. We carried out a greenhouse experiment involving a soil cadmium (Cd) concentration gradient (0.1, 0.5, 1, 2, 4, and 8 mg kg−1) to assess growth and phytoextraction capacity of king grass (Pennisetum sinese Roxb.) in soils contaminated by Cd and to explore changes in diversity and structure of rhizosphere soil bacterial communities in response to long-term Cd pollution. A significant positive relationship was observed between Cd concentrations in P. sinese stems, leaves, and roots and soil Cd concentration. The highest Cd concentrations in shoots and roots were 28.87 and 34.01 mg kg−1, respectively, at 8 mg kg−1of soil Cd supply. Total extraction amounts of Cd in P. sinese were 0.22–1.86 mg plant−1 corresponding to treatment with 0.5–8 mg kg−1 Cd. Most of the Cd was stored in shoots, and the largest accumulation was 1.56 mg plant−1 with 54.02 g dry shoot weight. After phytoextraction, changes in rhizobacterial community composition were found with different levels of Cd application, whereas there were no clear trends in diversity and richness. Results of this study show the feasibility of P. sinese in accumulating Cd and provide support for its application in remediation of soil moderately contaminated by Cd.

Brassinosteroids (Brs) are a class of plant polyhydroxysteroids and play pivotal roles in plant growth and development. Furthermore, Brs are involved in the responses of plants to various heavy metal stresses. However, the role of Brs in the translocation and uptake of arsenic (As) and cadmium (Cd) in rice (Oryza sativa L.) remains largely unknown. The present study was performed to examine the impacts of 24-epibrassinolide (Br24: 10−10 and 10−8 M), 28-homobrassinolide (Br28: 10−10 and 10−8 M), FeSO 4 addition (1 g kg −1 Fe) and their interactions on the accumulation of As and Cd by rice in pot trials. The results showed that the Fe content in iron plaque was increased by Fe addition but not by Br24/Br28. The interactions of Br24/Br28 and Fe enhanced the Fe contents in roots and stems. Br24/Br28 or Fe addition decreased the translocation and accumulation of As and Cd in rice grains. The interactions of Br24/Br28 or Fe further reduced the contents of As and Cd in rice grains. The As contents in grain were reduced by 60% under Fe addition, 18%–63% under Br24, 56%–73% under Fe+Br24, and 66%–72% under Fe+Br28. The grain Cd contents were reduced by 65% under Fe addition, 33%–61% under Br24, 56%–67% under Fe+Br24, and 43%–66% under Fe+Br28. These results suggest that the application of Fe, Br24/Br28 or their combination is effective in reducing the contents of As and Cd in rice grains, which has strong implications for agricultural production and food security.

Sulfur (S) is an essential element for plant growth and its biogeochemical cycling is strongly linked to the species of heavy metals in soil. In this work, the effects of S (sulfate and elemental sulfur) treatment on the accumulation, distribution and chemical forms of Hg in rice growing in Hg contaminated soil were investigated. It was found that S could promote the formation of iron plaque on the root surface and decrease total mercury (T-Hg) and methylmercury (MeHg) accumulation in rice grains, straw, and roots. Hg in the root was dominated in the form of RS-Hg-SR. Sulfate treatment increased the percentage of RS-Hg-SR to T-Hg in the rice root and changed the Hg species in soil. The dominant Hg species (70%) in soil was organic substance bound fractions. Sulfur treatment decreased Hg motility in the rhizosphere soils by promoting the conversion of RS-Hg-SR to HgS. This study is significant since it suggests that low dose sulfur treatment in Hg-containing water irrigated soil can decrease both T-Hg and MeHg accumulation in rice via inactivating Hg in the soil and promoting the formation of iron plaque in rice root, which may reduce health risk for people consuming those crops.

Ir(III)-catalyzed synthesis of benzimidazoles has been realized under redox-neutral conditions by annulation of aniline derivatives with dioxazolones. The reaction proceeded via a C-H activation-amidation-cyclization pathway with a decent substrate scope.

An efficient and redox-neutral naphthol synthesis has been realized via rhodium(iii) catalyzed C–H activation of α-carbonyl nitrones and annulation with alkynes, where the nitrone group functioned as a traceless directing group.

In this study, metallurgical-slag-based binder (MSB) with different dosages of calcium hydroxide (CH) was mixed with high-arsenic-containing mine tailings (HAMT) to form green mining fill samples (GMFs) for As solidification/stabilisation (S/S). The As leaching characteristics of the GMFs were evaluated using pH-dependent leaching tests, semi-dynamic leaching tests and toxicity leaching tests. The effective diffusion coefficient (De) decreased from 6.98 × 10−14 to 5.90 × 10−15 cm2/s and the leachability index (LI) increased from 13.53 to 14.73 after 3 wt.% CH was added to the GMFs. The GMFs containing 0 wt.% CH (GMF-0C) and those containing 3 wt.% CH (GMF-3C) reached pH = 2 with acid addition amounts of 9.0 meq/g-dry and 9.3 meq/g-dry at 90 d curing time, and the maximum As leaching concentrations of GMF-0C and GMF-3C reached 10.47 mg/L and 7.47 mg/L, respectively, indicating that GMF-3C exhibited better acid neutralisation and As retention capacities than GMF-0C. Further, a Tescan Integrated Mineral Analyser (TIMA) was used to analyse the dominant hydration products of GMF-3C, which revealed that calcium silicate hydrate, CASH, ettringite and zeolite phases represented approximately 22.5 wt.% of the products. These results provide an understanding regarding the safe large-scale utilisation of GMFs.

Immobilization is widely used to decrease the availability of heavy metals, such as Cd and Pb, in contaminated soils. However, the spatial and temporal changes in the immobilization of soil by amendments combined with planting effects have not been studied well. In this study, unplanted and planted (with rice plants) pot experiments were used to assess the spatial and temporal changes in water-soluble Cd, Fe, Mn, and Ca. Soil properties, such as pH, redox potential (Eh), and dissolved organic carbon (DOC), were continuously recorded in both the rhizosphere and bulk soil using non-invasive rhizon samplers and a microelectrode system (Unisense). In unplanted soil, pH and Eh varied with time, but showed little radial variation from the rhizosphere to the bulk soil. The addition of hydrated lime (Ca(OH)2) sharply increased the pH, DOC, and Ca content; decreased the Eh, Fe content, and Mn content; and gradually decreased the water-soluble Cd content in the soil profile. Hydroxyapatite showed no obvious effects in reducing Cd concentrations in different soil zones. The water-soluble Fe, Mn, Ca, and DOC content did not differ significantly between soil zones over time and a non-significant correlation with water-soluble Cd was shown. In planted soil, the pH increased while the Eh value decreased with an increase in the distance from the roots, regardless of the soil amendments used during the rice growth period. Hydroxyapatite gradually increased but hydrated lime decreased the water-soluble Cd in the rhizosphere. The concentration of water-soluble Cd in the rhizosphere was higher than that of the other soil zones during rice growth. These changes lead to more Cd uptake by roots and induced Cd accumulation in rice tissues. In addition, Cd and Fe concentration in iron plaque showed a significant positive correlation with Cd in rice, indicating that iron plaque promotes the uptake and accumulation of Cd in rice with soil amendments. Compared with the control, hydroxyapatite did not significantly affect the Cd content, while Ca(OH)2 significantly reduced the Cd content in iron plaque and rice tissues. In conclusion, the application of hydrated lime can significantly reduce the risk of Cd accumulation by rice in Cd-contaminated soils under flooding conditions.

The leaching characteristics of metallurgical slag-based binders (MSB) solidified/stabilized tailings containing arsenic (As) and antimony (Sb), were investigated via a series of semi-dynamic leaching tests using three kinds of leachant, for the simulation of actual leaching conditions. The effectiveness of solidification/stabilization (S/S) treatment was evaluated by measuring the observed diffusion coefficients (Dobs). It was found that MSB efficiently prevented As and Sb leaching, providing Dobs values in the range of 10−15 to 10−13 cm2/s and 10−11 to 10−9 cm2/s, respectively, with the exception that the leaching mechanism of As was dissolution rather than diffusion under acetic acid leaching conditions. Physical encapsulation was found to be the dominant mechanism for Sb immobilization, while the dominant mechanism of As immobilization was precipitation in the monolithic MSB S/S treated tailings (MST). Results showed that the concentrations of leached As, Sb, Ca and Si, were affected by leachant pH and total acidity as well as the MSB constituent ratio. The effect of these parameters may be attributed to the stability of hydration products and their influence on the buffering capacity and structure of matrices, and the leachant pH and total acidity having the greatest influence on leaching characteristics.

Methylmercury (MeHg) in rice grains grown in Hg-contaminated areas has raised environmental health concerns. Pot experiments found that selenium (Se) could reduce MeHg levels in rice grains. However, relatively high levels of Se (up to 6 mg/kg) were applied in these pot experiments, which may have adverse effects on the soil ecology due to the toxicity of Se. The aims of this work were thus to study 1) the effect of low levels of Se on the accumulation and distribution of Hg, especially MeHg, in rice plants grown in a real Hg-contaminated paddy field and 2) the effect of Se treatment on Se and other nutritional elements (e.g., Cu, Fe, Zn) in grains. A field study amended with different levels of Se was carried out in Hg-contaminated paddy soil in Qingzhen, Guizhou, China. The levels of MeHg and total Hg were studied using cold vapor atomic fluorescence spectrometry (CVAFS) and inductively coupled plasma mass spectrometry (ICP-MS). The distribution and relative quantification of elements in grains were examined by synchrotron radiation X-ray fluorescence analysis (SR-XRF). This field study showed that low levels of Se (0.5 μg/mL, corresponding to 0.15 mg Se/kg soils) could significantly reduce total Hg and MeHg in rice tissues. Se treatment also reduced Hg distribution in the embryo and endosperm and increased the levels of Fe, Cu, Zn and Se in grains and especially embryos. This field study implied that treatment with an appropriate level of Se is an effective approach to not only decrease the level of MeHg but to also increase the levels of nutritional elements such as Fe, Cu, Zn and Se in rice grains, which could bring beneficial effects for rice-dependent residents living in Hg-contaminated areas.

The influence of elemental sulfur (S(0)) amendment on methylmercury (MeHg) accumulation in rice and the chemical form of Hg in the rhizosphere were investigated under waterlogged conditions in Hg-contaminated soil (the majority of the Hg (˜70%) in forms similar to HgS). Different levels of S(0) addition increased the MeHg accumulation in rice. After a sequential extraction analysis of the chemical forms of Hg in the rhizosphere, the results showed that S(0) addition increased the organic bound Hg and decreased the residual Hg in the soils. An Hg LIII XANES further showed that S(0) addition increased the proportion of Hg in the form of RS-Hg-SR and decreased the proportion of Hg in the form of HgS, indicating that S(0) input may reactivate the non-bioavailable Hg in the rhizosphere and improve the net Hg methylation. These findings suggest that the application of S fertilizers to Hg-contaminated paddy soils may increase the MeHg concentration in the edible parts of crops, which may lead to more potential health problems in humans depending on the crop type. However, our study also suggests that S(0) addition could be an effective measure for mobilizing the insoluble Hg and accelerating the phytoremediation process in Hg-contaminated paddy soils.

Mercury (Hg) is a global pollutant that poses a serious threat to human and the environment. Rice was found as an important source for human exposure to Hg in some areas. In this study, the transportation and transformation of IHg and MeHg in rice plants exposed to IHg or MeHg were investigated. The IHg and MeHg concentrations in rice roots and shoots collected every five days were analyzed by HPLC-ICP-MS and SR-XANES. When exposed to MeHg, the percent of IHg in rice roots and shoots increased while MeHg decreased significantly, suggesting prominent demethylation of MeHg occurred. However no notable MeHg was found in both roots and shoots of rice plant when exposed to IHg. SR-XANES analysis further confirmed the demethylation of MeHg with rice. This study provides a new finding that demethylation of MeHg could occur in growing rice, which may be a self-defense process of rice plant.

Iridium(III) and rhodium(III) complexes can catalyze the carbocyclization between 2-phenylimidazo[1,2-a]pyridine and α-diazo esters. The reaction occurs via CH activation and dialkylation of the arene followed by intramolecular nucleophilic substitution. Iridium(III) and rhodium(III) catalysis offer complementary scopes with respect to the α-diazo esters.

Micro/nanostructures with high aspect ratios in silicon wafers obtained by plasma etching are of great significance in device fabrication. In most cases, the scallop nanostructure in deep silicon etching should be suppressed. However, the scallop nanostructure could be applied in electronic device fabrication as characteristic information, which indicates the balance between deposition and etching. In this work, the applications of scallop nanostructures in etching process optimization and environmental protection are demonstrated. In addition, the minimum effect of the cycle time on the scallop size is reported for the first time. These results could bring new thoughts to the electronic devices related fields, such as micro-electro-mechanical systems (MEMS), silicon capacitors and advanced packaging.

A fluorescent nanoprobe based on yellow-emissive carbon dots (Y-CDs) has been constructed for selective and sensitive sensing of 2,4,6-trinitrophenol (TNP). Y-CDs with a large Stokes shift (115 nm) were obtained through a simple one-pot solvothermal method. Significantly, the addition of TNP induced remarkable quenching of fluorescence intensity of Y-CDs via an inner filter effect. There was a good linear relationship between the fluorescence of Y-CDs and TNP concentration (0.2–130 μM), displaying a limit of detection of 56 nM. The nanoprobe can selectively detect TNP without interference from other nitroaromatic explosives, and has been successfully used for determining TNP in environmental water samples, representing a convenient tool for TNP sensing in environmental samples.

Mercury (Hg) pollution seriously threatens food safety and has attracted global attention. Phytoextraction, due to its low cost, applicability, and environmental friendliness, is considered a new technology for clean-up of heavy metal contamination in the environment. However, the low bioavailability of Hg in polluted areas greatly limits the applicability of phytoextraction. Here, we compared the effects of six common chelating ligands on the absorption and transport of Hg in maize (Zea mays L.), which has a high biomass and short growth cycle. The results showed that the root length and biomass of maize seedlings of the groups treated with the six chelating ligands (EDTA, iodide, ammonium, thiosulfate, thiocyanate, and thiocarbamide) did not change compared with those of the non-treated groups. Co-exposure to Hg and each chelating ligand markedly alleviated the inhibitory effect induced by Hg. Iodide treatment resulted in the lowest root Hg content and highest translocation factor (TF) value, while ammonium treatment gave rise to the highest shoot Hg concentration and lowest TF. Compared with other chelating ligands, thiosulfate exhibited the maximum alleviation of Hg toxicity and achieved the highest concentration of Hg in the roots and aerial parts. Moreover, the TF and Hg accumulation in the thiosulfate and Hg co-exposed group were much higher than those in the group exposed to Hg alone. This finding suggests that, among these common chelating ligands, thiosulfate compounds have great potential for Hg phytoextraction, while the others can immobilize Hg in polluted areas.

The mixture of finely ground blast furnace slag (BFS), basic oxygen furnace (BOF) steel slag (SS), and flue gas desulfurisation (FGD) gypsum could be used as cement to solidify heavy metals. In this study, these cementitious materials were combined with high-arsenic-containing tailings to form cemented backfill material (CBM). The results indicated that the optimal design of CBM was that of specimen CBM2 which showed good early strength (10.09 MPa) at a curing age of 3 days containing 60% BF slag, 30% SS, and 10% gypsum. And the arsenic leaching concentration of CBM2 at a curing age of 7 days and 28 days were both less than the limits specified in standards for drinking water quality (Chinese Standard GB 5749-2006). The predominant hydration products of CBM2 contained rod-like ettringite and amorphous C–S–H gel both of which promote arsenic solidification.

Rh(III)-catalyzed C–H activation of arenes and mild oxidative [4 + 2] annulative coupling with ketenes have been realized. The uniquely high reactivity of the C(3) of 2-phenylindoles was successfully utilized to facilitate the reductive elimination process, leading to efficient synthesis of cyclic products with a quaternary carbon stereocenter.

Background and aims: Iron plaque can affect the absorption and accumulation of metal(loid)s in plants. However, it is still unclear whether iron plaque plays different roles in the accumulation of different mercury species in rice plants. The aims of this study are 1) to explore the adsorption of IHg and MeHg onto iron plaque, 2) to investigate the influence of iron plaque on the absorption, translocation of IHg and MeHg in rice plants, 3) to explore whether the process of methylation and demethylation of Hg in vivo occurs in rice plants, and 4) to investigate the effects of iron plaque on the IHg and MeHg transformation in rice. Methods: The seedlings were cultivated in an Fe2+ soln. for 24 h to induce the iron plaque and then transferred into a nutrient soln. contg. 500 渭g/L HgCl2 or MeHgCl for 72 h. The Hg content in the iron plaque and rice seedlings was measured by ICP-MS. The chem. forms of Hg in the rice seedlings were detd. with HPLC-ICP-MS and XANES. Results: Both IHg and MeHg, particularly MeHg, could be adsorbed by iron plaque. The IHg content of the root and the MeHg content in both the roots and shoots decreased markedly with the increase in iron plaque. The Hg in the root was mainly in the form of RS-Hg-SR with the exposure to HgCl2 and in the form of CH3-Hg-SR and RS-Hg-SR (4:1) with the exposure to MeHgCl. The iron plaque did not change the chem. forms of Hg in the rice plants. Conclusions: Iron plaque greatly decreased the absorption and translocation of both IHg and MeHg in rice seedlings. The demethylation of MeHg occurred in rice plants (in vivo) regardless the formation of iron plaque. This work sheds some light on the understanding of different pathways between IHg and MeHg in rice plants. [on SciFinder(R)]

Aims The consumption of rice grain produced in mercury (Hg) contaminated soil was identified as a major route of dietary Hg exposure. The aims were 1) to determine the most suitable concentration of Se that can lead to least Hg accumulation in rice grain in real Hg contaminated paddy field in Qingzhen, and 2) to elucidate the possible mechanism of the protection against the phytotoxicity of Hg in rice by Se.

A comprehensive approach that can identify and quantify selenium (Se) in seleno-proteins in Se-enriched yeast was developed. The Se-containing compounds in Se-enriched yeast were first extracted and then the fraction of Se-containing proteins in the supernatant was analyzed by 2-dimensional electrophoresis (2-DE) and synchrotron radiation X-ray fluorescence (SR-XRF). The detection limit (DL) of SR-XRF analysis for Se quantification in Se-containing proteins after 2-DE separation was calculated to be 0.20 µg g−1, which is suitable for Se quantification in the Se-containing spots present on the 2-D gel. After being scanned by SR-XRF, only spots with a mean Se content exceeding twice the DL of SR-XRF were considered to be seleno-proteins. In this way, a total of 157 Se-containing spots in the gel were visually distinguished. Se contents in all the Se-containing proteins of different molecular weights were quantified. The total Se content on the 2-D gel was calculated to be 126.56 µg g−1, which covered most of the seleno-proteins on the 2-D gel.

A Rh(III)-catalyzed site-selective C–H activation of C(3)-functionalized indoles in a coupling with diazo esters has been realized with carbonyl as a weakly coordinating group. The coupling selectivity is dictated by the temperature and additives, affording either C4-alkylated indoles or C2-annulated lactones in moderate to excellent efficiency.

Rhodium(III)-catalyzed C–H activation of heteroarenes and functionalization with bifunctional substrates such as anthranils allows facile construction of quinoline-fused heterocycles under redox-neutral conditions. The couplings feature broad substrate scope and provide step-economical access to two classes of quinoline-fused condensed heterocycles.

Iridium(III) and rhodium(III) complexes can catalyze the carbocyclization between 2-phenylimidazo[1,2-a]pyridine and α-diazo esters. The reaction occurs via CH activation and dialkylation of the arene followed by intramolecular nucleophilic substitution. Iridium(III) and rhodium(III) catalysis offer complementary scopes with respect to the α-diazo esters.

Indoles are an important structural motif that is commonly found in biologically active molecules. In this work, conditions for divergent couplings between imidamides and acceptor-acceptor diazo compounds were developed that afforded NH indoles and 3H-indoles under ruthenium catalysis. The coupling of α-diazoketoesters afforded NH indoles by cleavage of the C(N2 )-C(acyl) bond whereas α-diazomalonates gave 3H-indoles by C-N bond cleavage. This reaction constitutes the first intermolecular coupling of diazo substrates with arenes by ruthenium-catalyzed C-H activation.

Rhodium(III)-catalyzed C–H activation of heteroarenes and functionalization with bifunctional substrates such as anthranils allows facile construction of quinoline-fused heterocycles under redox-neutral conditions. The couplings feature broad substrate scope and provide step-economical access to two classes of quinoline-fused condensed heterocycles.

Methylmercury is a toxic pollutant and is generated by microbial methylation of elemental or inorganic mercury in the environment. Previous study found decreased hepatic MDA levels and urinary mercury levels in methylmercury poisoned rats after sodium selenite treatment. This study further found increased mercury levels in serum samples from methylmercury poisoned rats after selenium treatment. By using size exclusion chromatography coupled to inductively coupled plasma mass spectrometry, three Hg- binding protein fractions and two Se-binding protein fractions were identified with the molecular weight of approximately 21, 40, and 75 kDa and of 40 and 75 kDa, respectively. Elevated mercury level in the 75 kDa protein fraction was found binding with both Hg and Se, which may explain the decreased urinary Hg excretion in MeHg poisoned rats after Se treatment. MALDI-TOF-MS analysis of the serum found that the 75 kDa protein fractions were albumin binding with both Hg and Se and the 21 kDa fraction was Hg- binding metallothionein.

In the presence of Au(I) the C—H alkynylation of 2-pyridones occurs at the most electron-rich 5-position via an electrophilic alkynylation pathway while the selectivity is switched to the 6-position under assistance of an N-chelation group when a Rh(III) catalyst is employed.

Formal regiodivergent C–H alkynylation of 2-pyridones bearing different N-substituents has been realized under Au(I) and Rh(III) catalysis using a hypervalent iodine alkyne reagent. When catalyzed by Au(I), the alkynylation occurred at the most electron-rich 5-position via an electrophilic alkynylation pathway. The selectivity was switched to the 6-position under assistance of an N-chelation group when a Rh(III) catalyst was employed. A rhodacylic complex has been isolated as a key intermediate.

Mercury is toxic with widespread contamination. Highly sensitive and selective approaches for mercury analysis are desired. Although conventional techniques are accurate and sensitive in the determination of mercury, these procedures are time-consuming, labor-intensive and dependent heavily on expensive instrumentation. In recent years, nanomaterial-based approaches have been proved to be effective alternatives in the detection and speciation of mercury. In this review, the development of different nanomaterial-based approaches was summarized, as well as their utilization for the detection of mercury in environmental and biological samples, such as gold nanomaterials, carbon nanomaterials, quantum dots and so on. Moreover, the speciation of mercury using nanomaterials was also reviewed.

Rice cultured in Hg- and/or Se-contaminated fields is an important food source of human Hg/Se intake. There are elevated Hg and Se levels in the soil of the Wanshan District, Guizhou Province. Here we attempted to explore how a Hg antagonist, Se, modulates the absorption and accumulation of inorganic mercury (IHg) and methylmercury (MeHg) in rice. The effects of Se on the content and transportation of Hg in hydroponic and soil cultured rice plants were examined. The results show that IHg mainly accumulated in the rice roots, but some also accumulated in the rice grain. In comparison to IHg, MeHg can be concentrated in the rice grain, and the proportion of MeHg in the rice grain may account for above 40% of the total Hg. Se can protect against Hg phytotoxicity in rice and inhibit IHg accumulation in rice tissues, but was not remarkable for MeHg at a low dosage exposure level in this study. These discrepancies imply mechanistic differences between IHg and MeHg absorption and accumulation in rice. This study illustrates that Se plays an important role in modulating Hg uptake, transportation and accumulation in rice. Therefore, Se is considered to be a naturally existing element that effectively reduces Hg accumulation in rice, which may have significant implications for food safety.

There is increasing evidence that oxidative stress is an important risk factor for arsenic-related diseases. Peripheral blood leukocytes constitute an important defense against microorganisms or pathogens, while the research on the impact of chronic arsenic exposure on peripheral blood leukocytes is much more limited, especially at low level arsenic exposure. The purpose of the present study was to explore whether chronic arsenic exposure affects oxidative stress of peripheral blood leukocytes and possible linkages between oxidative stress and arsenic-induced skin lesions. 75 male inhabitants recruited from an As-endemic region of China were investigated in the present study. The classification of arsenicosis was based on the degree of skin lesions. Arsenic levels were measured in drinking water and urine by Atomic Fluorescence Spectroscopy. Urinary 8-hydroxy-2'-deoxyguanosine (8-OHdG) was tested by Enzyme-Linked Immunosorbent Assay. 8-OHdG of peripheral blood leukocytes was evaluated using immunocytochemical staining. 8-OHdG-positive reactions were only present in polymorphonuclear leukocytes (PMNs), but not in monocytes (MNs). The 8-OHdG staining of PMN cytoplasm was observed in all investigated populations, while the 8-OHdG staining of PMN nuclei was frequently found along with the elevated amounts of cell debris in individuals with skin lesion. Urinary arsenic levels were increased in the severe skin lesion group compared with the normal group. No relationship was observed between drinking water arsenic or urine 8-OHdG and the degree of skin lesions. These findings indicated that the target and persistent oxidative stress in peripheral blood PMNs may be employed as a sensitive biomarker directly to assess adverse health effects caused by chronic exposure to lower levels of arsenic.