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Electron transfer in the electrode–solution interface is responsible for the signal in the electrochemical sensor. However, the Electrical Double-Layer (EDL) characteristic is usually ignored in signal modeling. Here, we constructed a model based on the reaction–diffusion equation to describe the dynamics in the EDL during sensing. With this model, many common experimental phenomena, such as transient/steady-state current variation or detection nonlinearization, can be unraveled by exploring the effects of position, kinetics proportionality coefficient (k), and reaction order (β). We also put forward some suggestions to improve the stability and linear detection range for future sensor design. [ABSTRACT FROM AUTHOR]

Low-rank coals are difficult to float using common hydrocarbon oily collectors, such as dodecane and diesel. In this investigation, a mixture of dodecane and n-valeric acid was used as a collector to enhance low-rank coal flotation. The changes in the induction time and surface functional groups of low-rank coal were measured before and after different collector's adsorption to indicate its absorption mechanism. The surface free energy was calculated to identify the interaction mechanism quantitatively between coal and collectors. The results showed that the flotation performance using the mixture as a collector was much better than that using dodecane or n-valeric acid solely. The induction time of coal conditioned with the mixed collector was the shortest, which meant the better hydrophobicity and floatability. When used the mixture as collector, the polar group of the n-valeric acid interacting with the oxygenated functional group on the coal surface by hydrogen bond while dodecane primarily covers the hydrophobic sites on the coal surface. Additionally, the mixed collector can minimize the surface free energy of raw coal, the dodecane primarily reduces the nonpolar part of the coal surface free energy while the n-valeric acid reduces the polar part of the coal surface free energy. [ABSTRACT FROM AUTHOR]

It is well known that the stability of hydration film on the particle surface affected the particle-bubble attachment in a flotation process. In this paper, the effect of attached nanosilica particles on the stability of liquid film around the coal particles was investigated by measurements of viscosity of the coal pulp and the bubble attachment time for coal particles. The interaction energy between a nanosilica particle and a coal particle was calculated using the EDLVO theory. Results showed that the nanosilica-coal attachment was driven by hydration attraction. And the stability of liquid film was weakened with the attachment of nanosilica particles, which is probably due to the change of surface roughness. In this case, the bubble-particle attachment time was reduced and further improved the flotation recovery of coal. [ABSTRACT FROM AUTHOR]

The article discusses the application of hydrophobic polystyrene nanoparticles as a collector for coal flotation, aiming to demonstrate the possibility of sorting coal fines with nanoparticles. The results of the flotation tests conducted in this study show that a clean concentrate was successfully obtained from floating high ash coal fines by using nanoparticles. The nanoparticles significantly increased the combustible recovery while kept the concentrate ash content at a low level. Contact angle measurements and electron probe microanalyzer micrographs indicate that the deposition of hydrophobic nanoparticle on coal surface increased the hydrophobicity and microscale roughness of coal particles, which was beneficial to flotation process. Although the current nanoparticles used were effective for coal flotation, the dosage consumption was relatively high due to the coagulation of nanoparticles. This suggests that it is important to increase nanoparticle colloidal stability and improve nanoparticle deposition selectivity for practical applications. [ABSTRACT FROM AUTHOR]

This experimental work on graphite flotation investigated the effect of energy input on flotation performance of three particle size fractions. Results obtained from flotation tests indicated that the required energy input rate increases with the decreasing particle size. The maximum graphite recovery of coarse particles was obtained at 121 J/min, while the optimum recovery of fine particles was obtained at 330 J/min. However, the demand of energy for each coarse particle is slightly higher than that of the fine particle in collision process. Numerical analysis showed that the streamlines have little effect on the trajectories of coarse particles, which can significantly contribute to a higher recovery of coarse particles in comparison with fine particles at the same energy input rate. [ABSTRACT FROM AUTHOR]

The effect of single frothers and their blends on bubble size, froth stability, and unburned carbon (UC) flotation performance was studied. Methyl isobutyl carbinol that produces smaller bubbles is efficient in floating ultrafine particles and producing concentrate. DF-250 that gives higher froth stability is effective for recovering coarse particles and improving recovery. The presence of DF-250 in the blend increases bubble size and significantly enhances froth stability, and hence the optimal flotation performance is achieved with 75% DF-250. It indicates that the frother giving high froth stability is better in UC flotation due to the little effect of UC on froth stability. [ABSTRACT FROM AUTHOR]

Objective: A simple pH and redox dual stimuli-responsive diketopyrrolopyrrole (DPP)-Cu 2+ complexes gated mesoporous silica nanoparticles (MSN) were prepared for precise drug delivery and controlled drug release., Method: MSN was prepared by sol-gel method and then laminated. Carboxylic acid (CA)-Pyrrolo[3,4-c] pyrrole-1,4-dione, 2,5-dihydro-3,6-di-2-pyridinyl (PyDPP) was grafted onto the surface of amino-functionalized MSN (MSN-NH 2 ) through a simple amide reaction and then complexed with Cu 2+ to form gated molecules after doxorubicin (DOX) loading., Results: Scanning electron microscopy (SEM), transmission electron microscopy (TEM), and Low-angle X-ray diffraction (XRD) showed that MSN with uniform particle size (100 nm) and porous structure was successfully prepared. The prepared MSN, MSN- NH 2 , and MSN-DPP were fully characterized by Zeta potential, Fourier transforms infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and nitrogen adsorption- desorption. High DOX-loading capacity (18.22%) and encapsulation efficiency (89.16%) were achieved by optimizing the mass ratio of MSN to DOX. Release studies showed that the gated molecules of our designed DPP-Cu 2+ complexes had a good blocking effect under physiological conditions (the cumulative release rate of drugs within 24 hours was only 4.18%) and responded well to the pH and redox glutathione (GSH) dual stimuli. In vitro cytotoxicity assay showed that MSN-DPP-Cu 2+ had good biocompatibility in both Hep G2 cells and L02 cells (the relative cell viability of both cells within 48 hours was above 97%), and the MSN-DPP-Cu 2+ @DOX could be triggered for efficient drug release in Hep G2 cells., Conclusion: The MSN-DPP-Cu 2+ described in this research may be a good delivery system for the controlled release of antitumor drugs and can provide a potential possibility for clinical application in the future., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.net.)