A facile ultrasonic route for the fabrication of graphene quantum dots (GQDs) with upconverted emission is presented. The as-prepared GQDs exhibit an excitation-independent downconversion and upconversion photoluminescent (PL) behavior, and the complex photocatalysts (rutile TiO(2)/GQD and anatase TiO(2)/GQD systems) were designed to harness the visible spectrum of sunlight. It is interesting that the photocatalytic rate of the rutile TiO(2)/GQD complex system is ca. 9 times larger than that of the anatase TiO(2)/GQD complex under visible light (λ > 420 nm) irradiation in the degradation of methylene blue.

A facile method based on capillarity-assisted assembly is used to fabricate high-performance surface-enhanced Raman scattering (SERS) substrates employing clean Au nanoparticles (NPs). This method is better than microchannel way because the former may supply large-area uniform assembly and overcome the uneven radial distribution. Such densely-arranged assembly of Au NPs exhibits high reproducibility and large Raman enhancement factors of 3 × 10 10 , arising from strong electromagnetic fi eld coupling induced by adjacent Au NPs. The spot-to-spot SERS signals show that the relative standard deviation (RSD) in the intensity of the main Raman vibration modes (1310, 1361, 1509, 1650 cm − 1 ) of Rhodamine 6G at a concentration of 1 × 10 − 10 M are consistently less than 20%, demonstrating good spatial uniformity and reproducibility. The SERS signals of sudan dye at a 1 × 10 − 8 M concentration also shows high reproducibility with a low RSD of < 20%. Further, the assembly substrate is stable, retaining excellent uniformity and sensitivity after storage for months. This assembly strategy integrating the advantages of low-cost production, high sensitivity, and reproducibility would signifi cantly facilitate practical SERS detection.

Nanomaterials have offered an opportunity for molecular imprinting to extract templates easily and achieve large binding capacity. In this paper, silicon nanowires were employed as the reinforcement material in protein molecular imprinting with dopamine as the monomer and bovine hemoglobin as the template molecule. In the experiments, the imprinted nanowires showed fast adsorption kinetics (took up 75% of the equilibrium amount during only 5 min), significant selectivity and large binding capacity (213.7 mg g À1 ) for the template protein. Furthermore, the stability and regeneration were also investigated, which indicated that the imprinted nanowires had outstanding reusability.

A facile Fe-doped carbon quantum dot based fluorescent sensor for dopamine sensing and bioimaging was constructed.

Standard procedures for determining 15N in the NH4+ fraction of 2 M KCl soil extracts convert NH4+ to N2 prior to isotope‐ratio mass spectrometry. We developed a new gas‐phase method for determining 15N in NH4+ by producing N2O. Producing N2O means that atmospheric contamination by N2 at natural abundance is not a problem. The method is more sensitive than other methods at lower enrichments, and as accurate and precise as other methods. Nitrous oxide is produced as a by‐product during the oxidation of NH4+ by alkaline OBr−. The reaction is catalyzed by Cu2+ and is pH‐dependent. The best practical conditions for producing N2O were when the NH3‐absorbing solution contained 0.005 M H2SO4 with 0.5 mM CuSO4, and when the molarity of the NaOH in the NaOBr was 10 M. Background N (0.20 µmol test−1) significantly diluted the theoretical enrichments for amounts of N <10 µmol test−1. Corrected enrichment values were accurate for amounts of NH4+‐N ≥1 µmol test−1. For amounts of NH4+‐N ≥1 µmol test−1, precision was determined with a CV of 5.6% at 0.10 atom % excess and with a CV of 0.3% at 10.00 atom % excess. The method is suitable for any matrix and has the potential for better performance if the background contamination could be lowered.

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A well-designed turn-on sensor has been constructed and used for the assay of oxytetracycline hydrochloride in real milk samples.

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