Self-healing materials have received increased attention because of their automatic detecting and repairing damage function. In this paper, a novel self-assembly and self-healing bionanocomposite was developed as a coating material for controlled release fertilizers. This nanotechnology-enabled coating is environmentally friendly and highly efficient and possesses a tunable nutrient-releasing characteristic. In the synthesis process, bio-based polyurethane coated urea (BPCU) was prepared by the reaction of bio-polyols with isocyanate. The BPCU was then modified by the layer-by-layer technology to prepare self-assembling modified BPCU (SBPCU). Last, hollow nano-silica (HNS) particles loaded with the sodium alginate (SA) were used to modify SBPCU to fabricate of self-assembling and self-healing BPCU (SSBPCU). The results show that the self-assembled materials were synthesized through electrostatic adsorption. The self-healing was observed through scanning electron microscopy and 3D-X-ray computed tomography, revealing the mechanism was that the repair agent released from HNS reacted with the curing agent to block the pore channels and cracks of the coating. As a result, the SSBPCU exhibited the highest hydrophobicity and surface roughness and thus the slowest release rate. For the first time, this work has designed a novel strategy to solve the bottleneck problem that restricts the development of a controlled-release fertilizer.
An electrochemiluminescence resonance energy transfer (ECL-RET) system that detects prostate-specific antigen (PSA) was created. Near-infrared (NIR)-emitting NaYF:Yb,Tm/Mn upconverting nanoparticles (UCNPs) are used as donors, and gold nanorods (GNRs) are used as acceptors. The ECL was enhanced nearly threefold by Mn doping, with an emission peak appearing at an NIR wavelength of 808 nm. Anti-PSA 1 (Ab) was bound to the surfaces of UCNPs after being modified with poly(acrylic acid) (PAA). As for acceptors, cetyltrimethylammonium bromide (CTAB)-capped GNRs were treated with 11-mercaptoundecanoic acid (MUDA) and then conjugated with Anti-PSA 2 (Ab). When PSA was added, donors and acceptors were brought in close proximity through specific interactions of antibodies and antigens, resulting in high quenching efficiency levels. Under optimal conditions, the linear range of detection was 3.75-938 pg/mL for PSA (R = 0.999), with a detection limit as low as 3.16 pg/mL. This method can be applied to detect PSA in human serums with satisfactory results. Graphical abstract An electrochemiluminescence resonance energy transfer system was developed for determination of prostate-specific antigen using near-infrared-emitting NaYF:Yb,Tm/Mn upconverting nanoparticles as donors and gold nanorods as acceptors.
The dewatering experiments of fine coal with different ash contents in the particle size range of 0.125 mm − 0 mm were investigated in this study. Structures of coal samples were characterized by X-ray diffractometer (XRD) and surface functional groups were detected by Fourier transform infrared (FTIR). Wettability and wetting heats of coal samples were determined by contact angle measurements and micro-calorimeter system, respectively. In this study, the dewatering results indicate that the ash content of fine coal had less effect on the coal dewatering than the coalification degree in the dewatering process. However, for the given coal sample the moisture content was significantly affected by the ash content while the coal particle size was less than 0.125 mm. The decrease of moisture content in coal sample after the ash was removed indicating that the hydrophobic property of coal surface was enhanced based on contact angle measurements and wetting heats. In addition, kaolinite played a primary role of minerals in coal for the coal dewatering.
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