A passive sampler (the polar organic chemical integrative sampler; POCIS) was assessed for its ability to sample natural estrogens (17β-estradiol, E2; estrone, E1 and estriol, E3) and the synthetic estrogen (17α-ethynylestradiol, EE2) in the outlet of a sewage treatment works over several weeks. The performance of the POCIS was investigated and optimised in the laboratory before field deployment with high recoveries (66-99%) were achieved for all estrogens. Moreover, it was shown that POCIS does not exhibit any preferential selectivity towards any of the target compounds. The sampling rates of E1, E2 and E3 were 0.018 ± 0.009, 0.025 ± 0.014 and 0.033 ± 0.019 L d(-1), respectively. Following field deployments of 28 days in the discharge of a sewage works, POCIS was shown to enhance the sensitivity of estrogen detection, especially for E3, and provide time-weighted average (TWA) concentrations of E1, E2 and E3, ranging from undetectable to 12 ng L(-1) upstream of the outflow of a sewage treatment works, 13 to 91 ng L(-1) at the outflow and 8 to 39 ng L(-1) downstream of the outflow. This revealed that E1, E2 and E3 are not completely removed during sewage treatment, with concentrations most likely being maintained by contributions from conjugated estrogen analogues. Grab water samples showed considerable variation in the concentrations of estrogens over a longer period (6 months). The results confirm that POCIS is an effective and non-discriminatory method for the detection of low concentrations of estrogens in the aquatic environment.

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The authors describe a rapid, sensitive and selective colorimetric assay for sialic acid (SA) based on the use of gold nanoparticles (AuNPs) modified with 3-aminophenylboronic acid (3-APBA) which acts as the recognition probe for SA. 3-APBA contains amino groups and boronic acid groups through which it can assemble on citrate stabilized AuNPs. It reacts with the cis-diol groups of SA by reversible formation of a cyclic boronate ester in slightly acidic buffer. Detection involves the sequential addition of AuNPs, phosphate buffer, 3-APBA and SA in a tube, vortex mixing, acquisition of photographic images or absorption spectra, and calculation of the result. The method is simple, rapid, and does not require cumbersome steps such as the preparation of stable boronic acid functionalized AuNPs as used in colorimetric sensing of saccharides. Under the optimum conditions, the ratio of absorbances at 700 and 520 nm increases linearly in the 0.15-1.00 mM SA concentrations range, and the detection limit is 60 µM. This is comparable to the detection limit obtained in other colorimetric assays reported. Acceptable intra- and inter-day precisions of three SA concentrations (0.50, 1.00 and 2.00 mM) ranged from 1.9-4.2% and 4.2-6.4%, respectively. The efficacy of the method was demonstrated by analyzing simulated human saliva which gave recoveries ranging from 98.7-106.0%. Graphical abstract Schematic of a colorimetric method for detection of sialic acid (SA) in simulated saliva. It is based on aggregation of gold nanoparticles with 3-aminophenyl boronic acid (3-APBA) which assembles on AuNPs while the boronic acid group binds to cis-diols of SA to form a boronate ester.

a Hierarchical molybdenum disulfide microspheres have been successfully prepared through a zinc ionassisted hydrothermal route followed by an acid corrosion strategy. It is found that the MoS 2 microspheres comprised of numerous nanosheets with few-layered feature exhibit a 3D flower-like morphology. It is believed that the MoS 2 /ZnS composites can act as a precursor for the formation of hierarchical MoS 2 microspheres. Additionally, the electrochemical properties of the as-prepared MoS 2 microspheres as an electrode material for supercapacitors have also been investigated. Compared with the MoS 2 nanosheet, the resultant MoS 2 microsphere demonstrates superior pseudcapacitive properties including high specific capacitance, good cycling and rate capability, which could be credited to its novel hierarchical architecture feature.

Surface properties always play a dominant role in the energy storage devices. Understanding the surface phenomena is the key to tune the energy storage device using biowaste based porous nano carbons. Here, Callerya atropurpurea pod derived peculiar porous nanocarbons are synthesized by pyrolysis at different temperatures without any synthetic templates approach. Elaborate analysis of surface textures on the effect of pore size, volume and specific surface area on specific capacitance and frequency response behavior of nanocarbons were studied in detail. Electrochemical characterizations establish the mutuality of porosity and microtextural properties of nanocarbons with specific capacitance.The electrochemical characterization of the novel materials as supercapacitor electrode shows a high specific capacitance of 326.54 F g −1 at 0.25 A g −1 in 1.0 M KOH. A practical symmetric supercapacitor device is fabricated with a specific capacitance of 86.38 F g −1 at 0.1 A g −1 , and high energy density of 27.0 Wh kg −1 . This symmetric supercapacitor also possesses outstanding capacitance retention of 92.16% for 5000 charge discharge cycles and also stability of 97.17%, after voltage holding at the maximum voltage for 100 hours. Present manuscript gives the strong evidence for structure-property relationships so that one can tune the energy storage devices effectively.