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Silver clusters usually have intriguing aesthetic structures and multiple application prospects in optical materials, chemocatalysis, bioimaging and chemosensors. However, these practical applications usually suffer from the instability of silver clusters. How to transform this disadvantage into an advantage for meaningful applications of silver clusters remains challenging. In this work, we judiciously prepared a silver cluster of Ag24 using an aggregation-induced emission (AIE) ligand. Due to the argyrophilia of sulfur, Ag24 can be easily destroyed by sulfur-containing pesticides such as ethion, releasing the AIE fragments. As a result, a “turn-on” emission change was observed, making Ag24 a potential chemosensor for detecting ethion in water dominated solutions. This work provides new thoughts for the design of silver cluster-based luminescent chemosensors, and broadens the application range of silver clusters.

Songnen plain is an important commodity grain base of China, and this is the first study on the comprehensive detection of multiple pesticides in groundwater. Based on an analytical method of 56 pesticides, 30 groundwater samples were collected and analyzed. At least 4 pesticides were detected in each sample and 32 out of 56 pesticides were detected. The average detected levels of individual pesticides were approximately 10-100 ng/L. Organophosphorus pesticides and carbamate pesticides were the dominant pesticides, and their percentage of total pesticide concentrations were 35.9% and 55.5%, respectively. Based on the spatial distribution, the characteristic of nonpoint source pollution was indicated in the whole study area except for a point source pollution with the influence of a sewage oxidation pond. Nine core pesticides and three distinct clusters of the core pesticides with various concentration patterns were revealed by cluster analysis. Linear regression identified a significant relationship between the cumulative detections and the cumulative concentrations, providing access to identify the outlying contaminant events that deviate substantially from the linear trend. A new insight for prediction of pesticide occurrence was provided by the Pearson correlation between some individual pesticide concentrations and the cumulative detections or the cumulative concentrations. According to health risk assessment, the residual pesticides posed medium risks for children and infants and approximately 90% of risks were composed of β-HCH, dimethoate, ethyl-p-nitrophenyl phenylphosphonothioate and methyl parathion. These findings contributed to establishing a database for future monitoring and control of pesticides in agricultural areas.

Very little is known about bio-oxidation tailings as an arsenic (As) pollution source. A comparison study was carried out between three flotation tailings (N1-1, N1-2 and N1-3) and three bio-oxidation tailings (N2-1, N2-2 and N2-3), collected from the Yangshu gold mine in China. A combined approach of mineralogy, geochemistry and environmental geochemistry was applied to explore geochemical and mineralogical properties, As fractions and its release behavior of the bio-oxidation tailings. The results showed that extremely high total As (TAs) of 25,200–27,100 μg/g (air-dry weight) observed in N2-1, N2-2 and N2-3 was about 30 times higher than that (616–940 μg/g) in N1-1, N1-2 and N1-3. The main elements were As, Ca, Fe and S, the mineral phases were gypsum (CaSO4) (accounting for >95 wt%), and the corresponding As was present as FeAsS and As2O5 in N2-1, N2-2 and N2-3. A larger amount of As in the water-soluble (5.80–9.98 μg/g), exchangeable (9.42–15.70 μg/g), carbonate-bound (29.23–63.36 μg/g) and Fe/Mn oxide-bound (5825–12,218 μg/g) fractions was found in N2-1, N2-2 and N2-3. Solution TAs released from N2-2 was higher than the level released from N1-1, and predominantly present in the oxidised form as arsenate As(V) in 192 h. The bio-oxidation tailings are able to release more As, and are a potential As pollution source of soil, surface and ground water.

Single crystal of iridium with two different orientations, [100] and [110] has been successfully prepared by electron-beam floating zone melting (EBFZM). The experimental results showed that the iridium single crystal with [100] orientation could be directly prepared without seeding at a low growth rate below 3 mm/min, and the single crystal with [110] orientation could be only obtained by seeding. The competitive growth of the bicrystal demonstrated that the [100] orientation of the iridium single crystal can overwhelm that of the [110] orientation at a growth rate of 2 mm/min. Moreover, the interface growth undercooling including curvature undercooling and kinetic undercooling has been calculated for iridium single crystal with these two orientations. The calculated data and analysis agree well with the experimental results.

Freshwater contaminants tend to precipitate into intertidal surface sediments, particularly in the estuary and intertidal zones during freshwater–seawater mixing. Quinolone-type antibiotics are such contaminants, and their concentrations in the intertidal sediments are important indicators for the whole spectrum of antibiotics used in the estuary and adjacent areas. The impacts of sediment types and environmental factors on the distribution of 16 quinolones were probed based on nine Bohai and 42 Yellow Sea intertidal sediment samples. The samples were collected from locations along the coastal areas in China. Quinolones were detected in all samples, while moxifloxacin, ciprofloxacin, and ofloxacin were detected at a frequency >50%. Sediment types, pH, organic carbon content, K, Na and Fe concentrations had little correlation with quinolone distributions in intertidal sediments. However, combined concentrations of Ca + Mg (46.7 g/kg in Bohai and 13.7 g/kg in Yellow Sea samples) appeared to correlate with oxolinic acid detecting frequencies (88.9% and 4.8%, respectively) and concentrations (2.0–10.1 μg/g and up to 3.09 μg/g, respectively). Different detection frequencies of the quinolones could be attributed to the formation of cation bridges between oxolinic acid and Ca + Mg, which results in dominant sorption of oxolinic acid at different locations and sediment matrices.

Both numerical and experimental approaches were conducted to investigate the electron beam floating zone melting (EBFZM) of iridium crystal. A finite element model was established and the temperature fields under different processing parameters were calculated and discussed. The heating power, the rod diameter and the movement of heating source significantly influence the temperature distribution in the iridium rod. Once the heating starts, the temperature quickly increases and gradually reaches the steady state. The melting zone enlarges with the increase of heating power, and the critical power for obtaining a complete melting zone is 5.5 kW ∼ 6.0 kW in 20 mm-diameter Iridium rod. With the upward movement of heating source, the melting zone obviously enlarges and the lower solid/liquid (S/L) interface becomes more planar. Then how to get a complete melting zone with a suitable volume and the control of a planar S/L interface were discussed. An optimized processing window was proposed and applied to the EBFZM of iridium crystal. An iridium rod 20 mm in diameter was successfully produced and the microstructural morphologies indicated that the initial polycrystalline microstructure will evolve into single crystal.

Gold tailings often release arsenic (As) contaminants into the surrounding environment. Microorganisms play an important role in the As cycle, whereas the effects of As on bacterial communities remain unclear. To reveal the effects of As on the diversity of bacterial communities and their As-tolerance potential, farmland soil and river sediment samples were collected at various distances from tailings in the Dandong area of northeastern China. The bacterial communities were analyzed using high-throughput sequencing of 16S rRNA genes. The membrane transport proteins ArsB and (or) ACR3 pump As(III) out of the cell to resist As toxicity. We studied the abundance and phylogeny of ArsB and ACR3 using PCR-based clone libraries and quantitative PCR. The bacterial community was divided into 10 phyla and 59 genera. The transformation from As(V) to As(III) was predominant, which was coupled with denitrification. Both ArsB and ACR3 likely evolved from different orders of Proteobacteria. The arsB gene seems to be more stable in bestowing bacteria with the capability to respond to the As concentration. Moreover, As with iron, manganese, and total organic carbon also influenced the clustering relationships of samples and bacterial distribution.

Freshwater mental contaminants which in the estuary tend to precipitate into intertidal surface sediments during freshwater-seawater mixing because of heavy water chemical reaction. The impacts of ferric hydroxide on the removal rate of Cr with increasing pH and salinity were conducted by laboratory simulation experiment. The removal rate of Cr by ferric hydroxide decreased with increasing pH from river water to seawater in the estuary; this is because pH changed the Zeta potential of ferric hydroxide. And with increasing salinity, the removal rate of Cr by ferric hydroxide firstly decreased and then increased. On the hand, Na+ entering the sliding surface, which could improve Zeta potential and stability of ferric hydroxide colloid, which leads to the amount of Cr removal by colloid aggregation decreased. On the other hand, there was competitive adsorption between Cland CrO42-/HCrO4-. In this study, Fe was the key factor of heavy metal Cr distribution with pH change.

A modified montmorillonite (MMT) was prepared using an acid activation-sodium activation-iron oxide coating method to improve the adsorption capacities of natural MMTs. For MMT, its interlamellar distance increased from 12.29 to 13.36 Å, and goethite (α-FeOOH) was intercalated into its clay layers. Two novel media-injected permeable reactive barrier (MI-PRB) configurations were proposed for removing arsenic from groundwater. Sand tank experiments were conducted to investigate the performance of the two MI-PRBs: Tank A was filled with quartz sand. Tank B was packed with quartz sand and zero-valent iron (ZVI) in series, and the MMT slurry was respectively injected into them to form reactive zones. The results showed that for tank A, total arsenic (TA) removal of 98.57% was attained within the first 60 mm and subsequently descended slowly to 88.84% at the outlet. For tank B, a similar spatial variation trend was observed in the quartz sand layer, and subsequently, TA removal increased to ≥99.80% in the ZVI layer. TA removal by MMT mainly depended on both surface adsorption and electrostatic adhesion. TA removal by ZVI mainly relied on coagulation/precipitation and adsorption during the iron corrosion. The two MI-PRBs are feasible alternatives for in situ remediation of groundwater with elevated As levels.

An ion chromatography method was developed for the simultaneous detection of three soluble herbicides (glyphosate, bentazone and picloram), three chlorine disinfection byproducts (monochloroacetic acid, dichloroacetic acid and trichloroacetic acid) and 12 anions in water (Cl(-), Br(-), SO4(2-), CO3(2-), ClO3(-), ClO4(-), BrO3(-), PO4(3-), NO2(-), NO3(-), CH3COO(-) and COO(-)). High linearity (r(2) > 0.996) was observed for all target analytes for each respective concentration range. The limit of detection and limit of quantitation were between 0.21-0.85 and 0.06-25.46 μg/L, respectively. However, the interference effect of Cl(-), NO3(-) , SO4 (2-) and CO3(2-) on some target analytes must be considered during the analysis. Sample pre-treatment by a hydrogen column (H-column) required to reduce the negative effect of CO3(2-). Additionally, sample pre-treatment by a sliver-hydrogen column (Ag-H-column) is required when Cl(-) > 100 mg/L and SO4(2-) 100 mg/L and SO4(2-) > 50 mg/L. When Cl(-) > 100 mg/L, SO4(2-) > 50 mg/L and CO3(2-) > 20 mg/L, the sample pre-treatment by either an Ag-H-Ba-column or an Ag-H-column and Ba-column is required to minimize interference.

Benzoic acid can affect the iron-oxide mineral dissolution and react with hydroxyl radical. This study investigated its effect on 1,2-dichloroethane removal process by siderite-catalyzed hydrogen peroxide and persulfate. The variation of benzoic acid concentrations can affect pH value and soluble iron concentrations; when benzoic acid varied from 0 to 0.5 mmol/L, pH increased while Fe(2+) and Fe(3+) concentrations decreased, resulting in 1,2-dichloroethane removal efficiency which decreased from 91.2 to 5.0%. However, when benzoic acid varied from 0.5 to 10 mmol/L, pH decreased while Fe(2+) and Fe(3+) concentrations increased, resulting in 1,2-dichloroethane removal efficiency which increased from 5.0 to 83.4%.

A sediment core collected from coastal zone near the Qiao Island in the Pearl River Estuary was analyzed for total metal concentrations, chemical partitioning, and physico-chemical properties. Three vertical distribution patterns of the heavy metals in the sediment core were identified, respectively. The dominant binding phases for Cu, Pb, Cr, and Zn were the residual and Fe/Mn oxides fractions. Cd in all sediments was mainly associated with exchangeable fraction. Influences of total organic carbon content and cation exchange capacity on the total concentrations and fractions of almost all the metals were not evident, whereas sand content might play an important role in the distributions of residual phases of Cr, Cu, Pb, and Zn. In addition, sediment pH had also an important influence on the Fe/Mn oxides, organic/sulfide and residual fractions of Cr, Cu, and Zn. Contamination assessment on the heavy metals in the sediment core adopting Index of Geoaccumulation showed that Cr, V, Be, Se, Sn, and Tl were unpolluted, while Cu, Ni, Pb, Zn, Cd, and Co were polluted in different degrees throughout the core. It was remarkable that the various pollution levels of the metals from moderate (for Cu, Pb, and Zn) to strong (for Cd) were observed in the top 45 cm of the profiles. The relative decrease of the residual fraction in the upper 45 cm of the core is striking, especially for Zn and Cu, and, also for Pb, and Cr. The change in fraction distribution in the upper 45 cm, which is very much contrasting to the one at larger depths, confirms that the residual fraction is related to the natural origin of these metals, whereas in the upper part, the non-residual fractions (mainly the Fe/Mn oxides fraction) are increased due to pollution in the last decade. The possible sources for Cu, Pb, Zn, and Cd contaminations were attributed to the increasing municipal and industrial wastewater discharges, agricultural runoff, atmospheric inputs, and runoff from upstream mining or smelting activities, which may be associated with an accelerating growth of economy in the Pearl River Delta region in the past decade.

Deformation textures and recrystallization textures of ultrafine grains pure copper produced by asymmetrical accumulative roll-bonding (AARB) and symmetrical accumulative roll-bonding (ARB) respectively were investigated using X-ray diffraction (XRD). It was found that dominant deformation textures of copper after 98.4% strain are {1 0 0} shear texture by AARB and {2 1 1} copper texture by ARB, a mixed “deformation–recrystallization” texture is observed during the first stage of recrystallization, dominant recrystallization texture is {0 0 1} cube texture in samples produced respectively by AARB and ARB. We suggest that deformation textures and recrystallization textures are controlled by the crystal structures and deformation methods of samples, some unusual properties in ultrafine grains pure copper are possibly unstable.

A method was developed for the determination of clenbuterol in porcine meat by iso- topic dilution mass spectrometry (IDMS). National Institute of Metrology of China (NIM) par- ticipated in the international comparison activity organized by Asia Pacific Metrology (APMP) and got an international mutual recognition result using this method. The important factors of the method, such as the spray voltage, mobile phase, chromatographic column, extraction, purification and filtration conditions were investigated to acquire optimum conditions. The opti- mization results showed that the composition and pH value of the mobile phase had effects on the response of the mass spectrum of clenbuterol and the optimal value of the spray voltage. The solvent of sample had influences on the chromatographic retention behavior of clenbuterol. It was found that methanol caused a serious solvent effect, even made chromatographic peak split. Since clenbuterol was easily adsorbed on hydrophilic filter membranes and solid phase extraction columns, there were interference suppressions for the quantification of clenbuterol because of the eluate of the solid phase extraction columns. The homogenate method with extraction solvent of 0.1% (v/v) formic acid in acetonitrile had the highest extraction efficiency. The limit of the detection (LOD, S/N > 3) of the method was 0.2 μg/kg. The determination results of clenbuterol in the porcine meat by this method were 5.18 μg/kg ± 0.50 μg/kg (k = 2). This method is accurate, reliable, reproducible, and suitable for the determination of clenbuterol with trace quantity in porcine meat.

Several Daucus carota (carrot) and Nicotiana tabacum (tobacco) cell lines that had been selected as resistant to Pro, Trp, Lys and Met analogs were thawed after over 10 years of cryostorage in liquid nitrogen. Some of these cell lines had been cloned. Viable cells were recovered in all cases, and growing lines were recovered from the carrot lines when placed either on feeder plates or directly into liquid medium. Some tobacco cultures were recovered only in liquid medium, but two Trp analog-resistant cloned lines could not be recovered after several attempts. Generally the cryopreserved lines retained the original resistance and corresponding free amino acid levels while the same lines maintained as callus with monthly transfers for the same period often lost the resistance. Our study shows that carrot and some, but not all, tobacco cultured cell lines can be cryopreserved for over 10 years and still be recovered with their original characteristics.

The photosynthetic cell suspension culture of soybean [Glycine max (L.) Merr. cv. Corsoy] (SB-M) was successfully cryopreserved in liquid nitrogen using a preculture and controlled freezing to −40° C (two-step) freezing method. The effective method included a preculture treatment with gradually increasing levels of sorbitol added to the 3% sucrose already present in the medium. The cells were then placed in a cryoprotectant solution [10% DMSO (dimethylsulfoxide) and 9.1% sorbitol, or 10% DMSO and 8% sucrose], incubated for 30 min at 0° C, cooled at a rate of 1° C/min to −40° C, held at −40° C for 1 h, and then immersed directly into liquid nitrogen. The cells were thawed at 40° C and then immediately placed in liquid culture medium. The cell viabilities immediately after thawing were 75% or higher in all cases where cell growth resumed. The original growth rate and chlorophyll level of the cells was recovered within 40 to 47 d. If the sorbitol level was not high enough or the preculture period too short, growing cultures could not be recovered. Likewise, survival was not attained with cryoprotectant mixtures consisting of 15% DMSO, 15% glycerol, and 9.1% sucrose or 15% glycerol and 8% sucrose. The successful method was reproducible, thus allowing long-term storage of this and certain other unique photosynthetic suspension cultures in liquid nitrogen.

Seven suspension-cultured lines of five different species (Amaranthus powellii Datura innoxia, Glycine max, Gossypium hirsutum, andNicotiana tabacum × Nicotiana glutinosa fusion hybrid), which had been grown under photomixotrophic conditions, were placed under heterotrophic conditions (darkness and media with 3% sucrose or starch) where the chlorophyll levels declined to near zero. After three transfers over a 70-d period, the cells were placed back into photomixotrophic or photoautotrophic conditions where regreening occurred rapidly and continued growth was observed. This rapid adaptation to photosynthetic conditions contrasts with the original initiation process for these cultures, which required many months and an apparent selection since many of the original cells died. Thus, these seven photosynthetic cell suspension cultures appear to be different from the original cultures due possible to genetic or adaptive changes.