Papers by Keyword: Surface Modification

Abstract: The surface of magnesium hydroxide (MH) was modified with a silane coupling agent A-174 (3-methacryloxypropyltrimethoxysilane) to improve MH dispersion and hydrophobicity. The effects of modification on the resultant product and the mechanisms involved were studied through activation index analysis, thermogravimetric analysis, Fourier transform infrared spectroscopy and scanning electron microscope. The optimum modification conditions were obtained as follows: an A-174 dosage of 1.5 wt.% at 145 °C for 10 min at a stirring rate of 3000 rpm. A chemical reaction was observed between the MH surfaces and A-174. The dispersion and hydrophobicity of MH remarkably improved after surface modification.

Abstract: Removal of phenols from waters and wastewaters is an important issue in order to protect public health and environment. In an effort to develop an effective adsorbent for removal of phenol from aqueous solutions, fly ash cenospheres (FACs), the solid wastes generated from a coal-firing power plant, were modified with an amino-terminated organosilicon (γ-aminopropyltriethoxysilane, KH550). Surface properties of the KH550-modified FACs (M-FACs) were characterized by the X-ray diffraction (XRD), the scanning electron microscopy (SEM) and X-ray photoelectron spectra (XPS). The characterized results showed that KH550 was successfully grated on the surface of FACs. The effects of various experimental parameters such as solution pH, adsorbent dose, and temperature upon the phenol adsorption onto M-FACs were evaluated. The results showed solution pH had a major impact on the phenol adsorption onto M-FACs, the optimum phenol removal was observed around pH 7-9. The kinetic studies indicated that the adsorption process was best described by the pseudo-second-order kinetics, suggesting that the mainly phenol adsorption process was predominantly controlled by chemical process. M-FACs presented more than double adsorptive capacity as compared with FACs. The adsorption capacity of the regenerated adsorbents could still be maintained at 83% by the fourth adsorption-desorption cycle.

Abstract: In this study, the applications of CdSe/ZnS quantum dots (QDs) and its role in advanced sensings has been explored. The CdSe/ZnS was synthesized by using hot injection method with the shell ZnS layer was made using successive ionic layer adsorption and reaction (SILAR) method. The morphology of the CdSe/ZnS QDs was studied using Transmission Electron Microscope (TEM) and the average particle size was in 10-12 nm range. The prepared QDs were optically characterized using spectrofluorescence and strong emission was observed at 620 nm. Comparison of the fluorescence emissions of CdSe/ZnS capped with various capping ligands such as L-cysteine, thioglycolic acid (TGA), mercaptopropionic acid (MPA), mercaptosuccinic acid (MSA) and mercaptoundecanoic acid (MUA) were studied. The CdSe/ZnS capped with TGA gave the strongest fluorescence emission compared to others.

Abstract: Combined treatment including vacuum arc deposition a hard nanocrystalline TiCuN coating followed by electron-beam treatment has been carried out in the present work. The structure and phase composition of surface layer have been studied by scanning and diffraction transmission electron microscopy. The modes of treatment leading to a dramatic improvement of microhardness and wear-resistance of modified material have been determined. It has been established that the combined treatment results in microscopic delamination of the silumin by elements and an interlayer of thickness ~20 nm dominated by silicon atoms is formed along the coating substrate interface.

Abstract: We reported the preparation of surface modified poly(butylene terephthalate)-co-poly(butylene succinate)-b-poly(ethylene glycol) (i.e. PBT-co-PBS/PEG) films by three methods: silk fibroin coating, SO₂ plasma treatment and silk fibroin anchoring. The obtained composite films were named SF/(PBT-co-PBS/PEG), SO₂/(PBT-co-PBS/PEG) and SF/SO₂/(PBT-co-PBS/PEG), respectively. Their surface properties were characterized by contact angles, surface energies and XPS. The biocompatibility of the films were further evaluated by the morphology, attachment, proliferation and viability of human salivary epithelial cells (HSG cells). Results revealed that SF/SO₂/(PBT-co-PBS/PEG) possessed the high surface free energy (59.67 mJ/m²) and could immobilize a great amount of fibroin (SF surface coverage: 26.39 wt%), which attributed to the formation of such polar groups as hydrosulfide group, sulfonic group, carboxyl and carbonyl ones in the process of SO₂ plasma treatment. The cell tests suggested that the silk fibroin anchoring could significantly enhance the biocompatibility of PBT-co-PBS/PEG, which implied the potential application of fibroin modified PBT-co-PBS/PEG for clinical HSG cells transplantation in artificial salivary gland constructs.

Abstract: One of the important directions of the research on coal washing is developing the non-toxic reagents with strong force and high selectivity. Compared with model strains, yeast designated Y21 as surface modifier for fine coal was isolated from lignite by traditional microorganism separation. Colony morphology, physiological and biochemical characteristics and some molecular sequence fragments show that the strain Y21 was Rhodotorula mucilaginosa. Through zeta-potential measurements and contact angle changes of coal samples caused by strain Y21, it was shown that strain Y21 can be selectively adhered onto the fine coal surface through the electrostatic interactions and the hydrophobic interactions. These observations lead to the conclusion that the adhesion of the yeast onto the coal surface could change zeta potential and the contact angle of coal particles. For both coal samples, the contact angle was sharply increased respectively in the pH range 3-4 and 2-4 as a result of Y21 strain adsorption. This indicates that as a result Y21 strain adsorption the coal surfaces have become more hydrophobic. These results indicated that the modified flotation and flocculation rate of fine coal particles were improved using the strain Y21 through changing the surface characteristics of coal.

Abstract: This paper aims at introducing and investigating the mechanical properties of new variety of natural fibers (Christmas palm fiber) used as reinforcement in polymer matrix composites. It was inferred that the poor inter laminar bonding between the Christmas palm fibers and polyester matrix restricted the mechanical properties of the composites. Hence surface modifications of Christmas palm fibers by means of alkali treatment were done in a view to enhance the bonding nature of the Christmas palm fiber with polyester matrix. The composite fabrication is carried out using compression moulding machine and the mechanical properties were tested as per ASTM standards. The effect of soaking time and solution concentration of Sodium hydroxide on the mechanical properties of Christmas palm fiber reinforced polyester composites were studied and fiber treatment conditions for better mechanical properties are identified. Scanning electron microscopy (SEM) investigations showed that surface modification improved the fiber/ matrix adhesion which in turn enhanced the mechanical properties of the Christmas palm fiber reinforced polyester composite.

Abstract: Poly (lactic acid) (PLA) is well known for their biodegradability and bioresorbable properties and these properties made them suitable in drug delivery system as drug carriers. PLA is relatively hydrophobic and lack of cell-recognition group to interact with biologically active molecules which reduce the surface compatibility of microspheres. In this project, alkaline hydrolysis was used to induce hydrophilic functional group on the microspheres surface. Alkaline solution at 0.01M and 0.1M was used to modify microspheres surfaces. The engineered surfaces were evaluated using Scanning Electron Microscopy and Water Contact Angle. 0.1M alkaline solution hydrolyzed microspheres at higher extends as compared to 0.01M, where partial microspheres disintegrated and porous structure was revealed. The water contact angle of PLA films shows decreased from 65 ̊ to range 42 47 ̊ after alkaline hydrolysis.

Abstract: This paper studies the Capacitance-Frequency of titanium dioxide (TiO₂) thin film-based interdigitated electrodes (IDEs) for ss-DNA immobilization. TiO₂ thin film was deposited on P-type silicon dioxide (SiO₂) (1 0 0) substrates using monoethanolamine (MEA) sol-gel route by spin-coating method. Titanium butoxide was used as a precursor source while ethanol and MEA were used as a disperser and stabilizer respectively. Metal IDEs of aluminium (Al) was deposited on the synthesized films for the electrical characterization. From the electrical data, it proves that the synthesized TiO₂ thin film is effective and can be used for the synthesis of TiO₂ thin films with biomedical application.

Abstract: Lately, nanostructure based biosensor application has drawn a lot attention among fellow researchers because of speciality to detecting cell, tissue and even disease caused by viruses either from humans, animals or agricultures. The nanostructure based biosensoris a result of the changed nature of nanomaterial to draw biomolecules and other biological samples based.In order to do so, formation of nanostructure based biosensor such nanowire must through a couplecritical or important processes such as trimming technique which leading towards formation of nanostructure while surface modification process leading towards by changing material of nanostructure behaviour to become biosensor. All the important process will be elaborated in technique section. Lastly in the result section, form structure produced, structure measurement and its behaviour will be elaborated.