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Human serum albumin (HSA) is considered as a biomarker for the early diagnosis of renal disease, therefore identifying and detecting HSA in biological fluids (especially urine) with an easy method is of great importance. Herein, we report a novel hydrazide Schiff base fluorescent probe N′-((7-(diethylamino)-2-oxo-2H-chromen-3-yl)methylene)pyrazine-2-carbohydrazide (NPC), which self-assembled into nanoparticles in aqueous solution. Based on disassembly-induced emission and the site-specific recognition mechanism, the binding of NPC with HSA resulted in a fluorescence "turn-on" response. Probe NPC exhibited superior selectivity and sensitivity toward HSA with a detection limit of 0.59 mg L−1 in PBS and 0.56 mg L−1 in the urine sample. The site-binding mechanism of NPC with HSA was explored by fluorescence quenching study, Job's plot analysis, HSA destruction, site marker displacement and molecular docking. Fluorescence imaging of HSA in MCF-7 cells was achieved by using a non-toxic NPC probe, suggesting that NPC could be applied to visualize the level of HSA in vivo. More importantly, further practical applications of probe NPC in human urine samples were achieved with satisfactory results by using a fluorometer or test paper, which could provide extensive application in clinical diagnosis. [ABSTRACT FROM AUTHOR]

A recent paper [Y. Q. Zhang, B. J. Chen, S. Xu, X. P. Li, J. S. Zhang, J. S. Sun, X. Q. Zhang, H. P. Xia and R. N. Hua, A universal approach for calculating the Judd–Ofelt parameters of RE3+ in powdered phosphors and its application for the β-NaYF4:Er3+/Yb3+ phosphor derived from auto-combustion-assisted fluoridation, Phys. Chem. Chem. Phys., 2018, 20, 15876–15883] used the Er3+/Yb3+:β-NaYF4 phosphor as an example to demonstrate a method used for evaluating Judd–Ofelt parameters of rare-earth-ion-doped powder. The method is actually established on the basis of a measured diffuse reflectance spectrum and fluorescence lifetime of Er3+ emission at 1.5 μm. The paper compared the Judd–Ofelt parameters obtained from two least-squares fitting processes with and without inclusion of two strong Er3+ absorption transitions from 4I15/2 to 2H11/2 and 4G11/2, and erroneously concluded that the values of the Judd–Ofelt parameters depend mainly on the majority of transitions with even weak intensities rather than on a few strong transitions. We have repeated the two fitting processes and the reverse conclusion has been made. Moreover, we have studied the effects of the transitions selected for the analysis and comprehensive explanations are given for the effects. In addition, the previously reported methods, including the aforementioned one, are reviewed, compared and discussed in detail. [ABSTRACT FROM AUTHOR]

In this paper, we have tried to prepare MgAl2O4 spinel by molten salt synthesis using hydroxide as solvent. By controlling the amount of KCl in KOH, pure flower-like MgAl2O4 nanostructures could be synthesized at 1150 °C. Powder X-ray diffraction, field emission scanning electron microscopy, and transmission electron microscopy were used to investigate the structures and morphologies of the obtained products. The results showed that the 3D flower-like nanostructures consisted of numerous 2D nanoflakes with a thickness of about several tens of nanometers. Further investigations on the possible formation mechanism revealed that a self-sacrificing template process dominated the formation of MgAl2O4 and the growth of the flower-like products was attributed to the competition between the growth rates along the directions perpendicular and parallel to the Al2O3 particle surfaces. Finally, an impedance-type humidity sensor was fabricated based on the flower-like MgAl2O4 nanostructures and tested for its humidity performance showing that the as-prepared MgAl2O4 nanostructures are suitable for high-performance humidity sensors. [ABSTRACT FROM AUTHOR]

A recent paper [Y. Q. Zhang, B. J. Chen, S. Xu, X. P. Li, J. S. Zhang, J. S. Sun, X. Q. Zhang, H. P. Xia and R. N. Hua, A universal approach for calculating the Judd-Ofelt parameters of RE3+ in powdered phosphors and its application for the β-NaYF4:Er3+/Yb3+ phosphor derived from auto-combustion-assisted fluoridation, Phys. Chem. Chem. Phys., 2018, 20, 15876-15883] used the Er3+/Yb3+:β-NaYF4 phosphor as an example to demonstrate a method used for evaluating Judd-Ofelt parameters of rare-earth-ion-doped powder. The method is actually established on the basis of a measured diffuse reflectance spectrum and fluorescence lifetime of Er3+ emission at 1.5 μm. The paper compared the Judd-Ofelt parameters obtained from two least-squares fitting processes with and without inclusion of two strong Er3+ absorption transitions from 4I15/2 to 2H11/2 and 4G11/2, and erroneously concluded that the values of the Judd-Ofelt parameters depend mainly on the majority of transitions with even weak intensities rather than on a few strong transitions. We have repeated the two fitting processes and the reverse conclusion has been made. Moreover, we have studied the effects of the transitions selected for the analysis and comprehensive explanations are given for the effects. In addition, the previously reported methods, including the aforementioned one, are reviewed, compared and discussed in detail.