scholarly journals Effects of Xanthate on Flotation Kinetics of Chalcopyrite and Talc

Minerals ◽  
2018 ◽  
Vol 8 (9) ◽  
pp. 369 ◽  
Author(s):  
Limei Bai ◽  
Jie Liu ◽  
Yuexin Han ◽  
Kai Jiang ◽  
Wenqing Zhao
Keyword(s):  
Physical Adsorption ◽  
Particle Morphology ◽  
Flotation Kinetics ◽  
Flotation Rate ◽  
Force Microscopy ◽  
Atomic Force ◽  
Angle Measuring ◽  
Particle Size Analyzer ◽  
Underlying Causes ◽  
Kinetics Of

This paper investigated the effects of using or not using potassium butyl xanthate (PBX) as a collector on the flotation kinetics of talc and chalcopyrite. By means of atomic force microscopy (AFM), Fourier-transform infrared spectroscopy (FTIR), a contact angle measuring instrument and particle size analyzer, the underlying causes behind the flotation rate changes of talc and chalcopyrite are analyzed. Experimental results showed that in collectorless flotation, the law of change in the flotation rate constant (k) of the two minerals over time is independent of pH, and k values of chalcopyrite are much smaller than those of talc. In the presence of PBX, the flotation speed of chalcopyrite greatly increases, and the k values of chalcopyrite are far larger than those of talc. This is mainly because the amount of xanthate adsorbed on the surface of chalcopyrite is large and the adsorption is in the form of chemisorption, while the adsorption of xanthate on the talcum surface is in very small amounts and in the form of physical adsorption. Simulation results indicated that the collectorless flotation of chalcopyrite conform to the classical first-order kinetics model and the Kelsall model, whereas that of talc only conform to the latter, which is due to the layered structure of talc. In the presence of the collector, talc flotation conforms to the two model, because talc has a higher floatability and particle morphology has less influence on the flotation rate.

scholarly journals Tunable control of antibody immobilization using electric field

2015 ◽  
Vol 112 (7) ◽  
pp. 1995-1999 ◽  
Author(s):  
Sam Emaminejad ◽  
Mehdi Javanmard ◽  
Chaitanya Gupta ◽  
Shuai Chang ◽  
Ronald W. Davis ◽  
...  
Keyword(s):  
Solid State ◽  
Electric Field ◽  
Signal To Noise Ratio ◽  
Physical Adsorption ◽  
Antibody Immobilization ◽  
Proof Of Concept ◽  
Force Microscopy ◽  
Atomic Force ◽  
Sensing Platforms ◽  
Glass Surfaces

The controlled immobilization of proteins on solid-state surfaces can play an important role in enhancing the sensitivity of both affinity-based biosensors and probe-free sensing platforms. Typical methods of controlling the orientation of probe proteins on a sensor surface involve surface chemistry-based techniques. Here, we present a method of tunably controlling the immobilization of proteins on a solid-state surface using electric field. We study the ability to orient molecules by immobilizing IgG molecules in microchannels while applying lateral fields. We use atomic force microscopy to both qualitatively and quantitatively study the orientation of antibodies on glass surfaces. We apply this ability for controlled orientation to enhance the performance of affinity-based assays. As a proof of concept, we use fluorescence detection to indirectly verify the modulation of the orientation of proteins bound to the surface. We studied the interaction of fluorescently tagged anti-IgG with surface immobilized IgG controlled by electric field. Our study demonstrates that the use of electric field can result in more than 100% enhancement in signal-to-noise ratio compared with normal physical adsorption.

scholarly journals AFM nanoindentation reveals decrease of elastic modulus of lipid bilayers near freezing point of water

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Calum Gabbutt ◽  
Wuyi Shen ◽  
Jacob Seifert ◽  
Sonia Contera
Keyword(s):  
Lipid Bilayers ◽  
Lipid Membranes ◽  
Structural Changes ◽  
Freezing Point ◽  
Liquid Environment ◽  
Force Microscopy ◽  
Atomic Force ◽  
Afm Imaging ◽  
Underlying Causes ◽  
Irreversible Injury

AbstractCell lipid membranes are the primary site of irreversible injury during freezing/thawing and cryopreservation of cells, but the underlying causes remain unknown. Here, we probe the effect of cooling from 20 °C to 0 °C on the structure and mechanical properties of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) bilayers using atomic force microscopy (AFM) imaging and AFM-based nanoindentation in a liquid environment. The Young’s modulus of elasticity (E) at each temperature for DPPC was obtained at different ionic strengths. Both at 20 mM and 150 mM NaCl, E of DPPC bilayers increases exponentially –as expected–as the temperature is lowered between 20 °C and 5 °C, but at 0 °C E drops from the values measured at 5 °C. Our results support the hypothesis that mechanical weakening of the bilayer at 0 °C  is produced by  structural changes at the lipid-fluid interface.

scholarly journals Preparation and Optical Application of SiO2-TiO2 Composite Hardening Coatings with Controllable Refractive Index by Synchronous Polymerization

Coatings ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 129
Author(s):  
Weiping Du ◽  
Shuting Cai ◽  
Yang Zhang ◽  
Huifang Chen
Keyword(s):  
Refractive Index ◽  
Titanium Isopropoxide ◽  
Hard Coatings ◽  
Reaction Conditions ◽  
Optical Lens ◽  
Force Microscopy ◽  
Hardness Tester ◽  
Hardening Coatings ◽  
Atomic Force ◽  
Particle Size Analyzer

The homogeneous SiO2-TiO2 composite sols were prepared by organic-inorganic synchronous polymerization with titanium isopropoxide and tetrabutyl silicate as precursor. The organic-inorganic composite hard coating with Si-O-Ti as the framework was prepared by adding compound crosslinkers (up-401) and 3-Methacryloxypropyltrimethoxysilane (KH-560). The structure of the coating and the hardened film were characterized by infrared spectrum, scanning electron microscopy, atomic force microscopy, particle size analyzer and thermogravimetry. The refractive index, transmittance and hardness of the hardened film were measured by ellipsometry, UV-Vis spectrophotometer and hardness tester. By adjusting the ratio of Si/Ti and optimizing the reaction conditions, the hardness of the hardened film could reach 6H, and the refractive index could be adjusted from 1.55 to 1.76. At the same time, the application of hard coatings on the surface of optical lens were studied.

Kinetics of the Nanohydrogel Flattening at a Hydrophobic Interface

2008 ◽  
Vol 8 (7) ◽  
pp. 3386-3391
Author(s):  
ImShik Lee ◽  
Haiying Sun ◽  
Jingxia Song ◽  
Ying Zhang
Keyword(s):  
Adsorption Mechanism ◽  
Pyrolytic Graphite ◽  
Force Microscopy ◽  
Atomic Force ◽  
Dynamic Observation ◽  
Membrane Mimetic ◽  
Aqueous Conditions ◽  
Unfolding Kinetics ◽  
Kinetics Of ◽  
Hydrophobic Interface

Hydrophobitized polysaccharides were designed to form the self-assembled nanohydrogels (hydrogel nanoparticles) in the aqueous conditions. For improving their biocompatibilities, they were decorated with the biomembrane-mimetic 2-methacryloyloxyethy1 phosphory1choline (MPC) polymers. The interfacial roles of the decorated membrane-mimetic nanohydrogels were investigated by choosing MPC branched choresteryl-bearing pullulan (CHP). Tapping-mode atomic force microscopy was used to study its adsorption mechanism on the hydrophobic highly oriented pyrolytic graphite (HOPG) surface in aqueous conditions. Dynamic observation at the interfaces revealed two distinctive patterns: the immobilized nanohydrogel particles and the flatten layers. The flattening (unfolding) kinetics with and without MPC branched nanohydrogel revealed that the flattening energy was at ∼37 kBT. The flattening rate of the MPC decorated nanohydrogels was ∼1.7 times faster than that without MPC decoration, corresponding to minor reduction of the flattening activation energy.

Kinetics of Linear Defect Formation in Gallia-Doped Rutile.

2004 ◽  
Vol 849 ◽  
Author(s):  
Nathan Empie ◽  
Doreen Edwards
Keyword(s):  
Single Crystal ◽  
Defect Formation ◽  
Sol Gel ◽  
Surface Concentration ◽  
Thermal Treatments ◽  
Rutile Structure ◽  
Force Microscopy ◽  
Linear Defects ◽  
Atomic Force ◽  
Kinetics Of

ABSTRACTThe diffusion of Ga2O3 into the surface of single crystal[001] rutile leads to the insertion of β-gallia subunits along {210} planes of the parent rutile structure. These linear defects introduce hexagonally shaped tunnels, approximately 2.5 å in diameter, normal to the]001] surface. Because these tunnels may serve as highly reactive sites for the attachment of macromolecules, we are exploring the application of these linear defects for creating nanostructures. The current work investigates the kinetics of defect formation and the factors that affect defect periodicity and orientation. Gallium oxide was applied to the surfaces of [001]-oriented TiO2 single-crystal substrates via a sol-gel spin-coating process using a gallium-containing precursor. Thermal treatments were systematically varied to obtain different defect surface structures. Defect orientation and the surface concentration of rows of defects were characterized via tapping mode atomic force microscopy.

scholarly journals Growth and Switching of Ferroelectric Nanocrystals from Ultrathin Film of Copolymer of Vinylidene Fluoride and Trifluoroethylene

2011 ◽  
Vol 2011 ◽  
pp. 1-5 ◽  
Author(s):  
R. Gaynutdinov ◽  
V. Fridkin ◽  
H. Kliem
Keyword(s):  
Self Assembly ◽  
Vinylidene Fluoride ◽  
Paraelectric Phase ◽  
Orthorhombic Space Group ◽  
Lb Films ◽  
Force Microscopy ◽  
Langmuir Blodgett ◽  
Storage Media ◽  
Atomic Force ◽  
Kinetics Of

The ferroelectric nanocrystals of the copolymer of vinylidene fluoride and trifluoroethylene P(VDF-TrFE) were grown from ultrathin Langmuir-Blodgett (LB) films on Si substrate. The annealing of ultrathin LB films with thickness of 3 monolayers (5 nm) in air in paraelectric phase at temperature 125∘C was performed. The self-assembly leads to the growth of nanocrystals of ferroelectric copolymer 15–25 nm thick and 100–200 nm in diameter. The nanocrystals presumably belong to orthorhombic space group, where axis 2 is the direction of spontaneous polarization (and normal to substrate). By means of atomic force microscopy (AFM), the kinetics of ferroelectric nanocrystals growth and their switching were investigated. The obtained results confirm the conclusions that copolymer nanocrystals are candidates for high-density nonvolatile storage media devices.

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