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Corrosion mechanisms for cemented soils in three different sulfate solutions
Pengju Han, Chao Ren, Xiaohong Bai, Frank Chen, 2015, izvirni znanstveni članek

Opis: In order to simulate and study the corrosion effects on the compressive strength of cemented soils that could be exposed in a polluted environment, a series of tests were conducted on cemented soil blocks cured with different concentrations of H2SO4, MgSO4, and Na2SO4 solutions. The test results show that the corrosion degree generally increases with the corrosion time and the solution concentration, while the compressive strength decreases with the increasing corrosion degree. The corrosion degree is highest for the Na2SO4 solution, followed by the MgSO4 and H2SO4 solutions. Namely, when the SO4 2- ion exists in a solution, the corrosion degree for the positive ions follows this descending order: Na+, Mg2+, and H+. X-ray diffraction (XRD) phase analyses were performed for the cemented soil samples after corrosion and ionic concentrations. The results show that the compressive strength decreases with an increase of the Mg2+ concentration in the MgSO4 solution and the Na+ concentration in the Na2SO4 solution. At the same time, the strength increases with an increase of the pH value of the H2SO4 solution. Based on the chemical analysis results, the corrosion of H2SO4 or MgSO4 solutions on cemented soils is deemed as a composite action involving the combined resolving and crystallizing corrosion processes. Furthermore, the corrosion of the Na2SO4 solution of cemented soil is a composite action consisting of dissolving and crystallizing.
Ključne besede: cemented soil, compressive strength, corrosion mechanism, sulfate, pollution, solution
Objavljeno: 15.06.2018; Ogledov: 773; Prenosov: 48
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Adsorption of fucoidan and chitosan sulfate on chitosan modified PET films monitored by QCM-D
Tea Indest, Janne Laine, Leena Sisko Johansson, Karin Stana-Kleinschek, Simona Strnad, Renate Dworczak, Volker Ribitsch, 2009, izvirni znanstveni članek

Opis: The adsorption behavior of fucoidan as well as chitosan derivatives (chitosan sulfate) on poly(ethylene terephthalate) (PET) model film surface was studied using the quartz crystal microbalance technique. These systems were chosen for this study due to their promising biocompatible properties. Moreover, fucoidan and chitosan sulfate have promising anticoagulant properties and represent an alternative to heparin treatment of vascular grafts. As a first step, PET foils were activated by alkaline hydrolysis to increase their hydrophilicity. From these foils, model PET films were prepared by the spin coating technique on a silica quartz crystal. The selected polysaccharides (chitosan, fucoidan, and chitosan sulfate) were adsorbed from aqueous solutions on the PET surfaces. The adsorption was monitored using a quartz crystal microbalance with a dissipation unit. The surface chemistry and morphology of the chitosan/fucoidan or chitosan/chitosan sulfate coated PET-H films was analyzed using XPS and AFM. It was found that chitosan/fucoidan films were thinner and more compressed, while in the case of chitosan/chitosansulfate, large amounts of chitosan sulfate were adsorbed, indicating a loose and thick adsorbed film.
Ključne besede: PET films, fucoidan, chitosan sulfate, adsorption, anticoagulant properties
Objavljeno: 01.06.2012; Ogledov: 1431; Prenosov: 83
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