Papers by Keyword: Microsphere

Abstract: The effect of bentonite (BT) on the structure and performance of sodium alginate (SA) as microsphere carrier of essential oil is studied. The addition of BT can improve the performance of alginate gel microspheres through the study of the properties of single carrier SA and composite carrier SA/BT. The experimental results show that the viscosity of composite carrier SA/BT solution is higher than that of carrier SA solution, and the increasing rate of viscosity of composite solution with temperature is less than that of SA. The addition of BT can effectively inhibit the swelling of SA microspheres. The hydrogen bonding between SA and BT is shown in FTIR, and the interlayer spacing of BT crystal structure is not changed in XRD analysis. The mass loss rate of SA/BT microspheres is lower than that of SA in TGA analysis. The more dense structure of SA/BT microspheres than that of SA microspheres is confirmed by SEM. The release rate of cinnamon oil in SA/BT gel microspheres is significantly lower than that in SA gel microspheres under different temperature conditions. The addition of BT could better control the volatilization of essential oil encapsulated in SA gel microspheres.

Abstract: Photonic jet microscopy is a technical field of microscopy applying photonic jet phenomenon to increase the resolution of objects or area of objects being observed. Mostly it is used in optical microscopy as the demand of visual observations are increased, especially for the micro-metric biological objects. In addition to our previous works inoptical assessment of observing a micrometric object under a microsphere using an optical microscope, now we made the electromagnetic assessment. It concludes if smaller microsphere magnifies greater than bigger microsphere. Therefore, applying photonic jet microscopy for visual observation is getting closer.

Abstract: Supercritical fluids (SCFs) process can be considered as an emerging ”clean“ technology for the production of small-size particles (e.g. micron-size). Microsphere is a material in micron scale which has been widely used as adsorbent, catalyst support, and drug delivery system. For advanced application, those materials are formulated in the form of porous microspheres. There are several methods that can be used using SCFs. One of them is Solution Enhanced Dispersion by Supercritical Fluids (SEDS). This method is considered to be suitable in obtaining the porous microsphere polystyrene. In this study, polystyrene was first dissolved into toluene (polystyrene solution) at different concentrations (i.e. 3, 5, 7, 9, 11, 13, 15 wt%) and then blown/sprayed together with supercritical carbon dioxide (CO₂) through co-axial nozzle with two differents annulus diameter (i.e. 3.6 mm and 4.6 mm). Co-axial nozzle consists of two concentric pipes, inner pipe and annulus. Inner pipe for polystyrene solution flow and annulus for supercritical carbon dioxide flow. The expansion of these two of fluid was done both in atmospheric condition and in pressurized precipitator (40 bar). The resulted microsphere was analyzed by using SEM (Scanning Electron Microscope) to determine morphology and average diameter of the microsphere. The SEM analysis results showe that the smaller the initial concentration of solution used, the resulted microspheres tend to be smaller and less fibrils formed. Additionally, in the pressurized precipitator, the formed microspheres size was smaller and size distribution more narrow than that of atmospheric condition. Moreover, the use of smaller annulus diameter in co-axial nozzle produced smaller microsphere size and the size distribution was more uniform.

Abstract: Hollow aluminum and silica microsphere is a component of ash wastes from heat and power industry that today is widely used as a microaddition almost in all sectors of economy. It is used to improve properties of different materials and constructions or to produce advanced properties of these materials. Hollow aluminum and silica microsphere is non-reactive microaddition that determine its advantages in producing ecologically friendly materials and in providing materials with additional properties without changing the basic. In this paper research has been conducted on identifying the modulus of viscosity focused on the effect on the capacity to form structure links that are influence the properties of producing leak less framework. Modulus of viscosity is one of the main dynamic characteristics of fill finely divided materials that determine materials and constructions strength properties including the capability to form a rigid frame. The research was carried out to determine the correlation between the modulus of viscosity and the humidity of raw component in order to identify optimal conditions of material formation and producing an item with the highest level of durability and rigidity. Moreover, the paper revealed the connection between the modulus of viscosity and the size of non-reactive microaddition based on set humidity and the influence of the microaddition size on the trend in modulus of viscosity.

Abstract: High emissive Ca²⁺/Fe³⁺-doped LaAlO₃ based ceramic materials were prepared by flame spraying and controlled crystallization method. The phase composition, microstructure, infrared optical properties of Ca²⁺/Fe³⁺-doped LaAlO₃ based ceramic powders were investigated. The physical mechanism for the significantly enhanced infrared emissivity of LaAlO₃ by doping with Ca²⁺ and Fe³⁺ was analysized. This high emissive Ca²⁺/Fe³⁺-doped LaAlO₃ based ceramic materials shows promising applications in high temperature thermal process field to enhance the radiative heat transfer and improve its thermal efficiency.

Abstract: Irradiation technique is one of methods used in modification of polymer surface although it has been used in sterilization for decades. It allows establishing simple and compact technique, non-contaminated with residues of toxic initiators, crossing agents or other additives. This study is to evaluate the effects of different gamma (γ) irradiation doses on poly (lactic acid) (PLA) microsphere surface grafted with maleic anhydride (MAH). Source of γ-irradiation used is ⁶⁰Co and dose irradiation used in this study is10, 30, 50, 70, 90 and 110 kGy. Characterization was performed on samples before and after irradiation by FTIR, SEM and DSC. Results of FTIR suggest maleic anhydride successfully grafted onto PLA microsphere. Data from DSC shows thermal property of PLA changed after irradiation where the crystallization is increased compared to neat PLA. SEM images showed the difference of the PLA microspheres before and after γ irradiation. Neat PLA microspheres had a smooth surface, while after irradiation, the surface become rough. Degradation of microspheres observed by SEM as in suggest that PLA microspheres is degrade by bulk degradation. Gamma irradiation not only modified the surface of PLA microspheres by successfully grafting the maleic anhydride and increase surface roughness, it also affected the bulk properties of PLA microspheres.

Abstract: Whispering gallery mode (WGM) resonance is used for the diameter measuring method of a microsphere smaller than φ 1 mm. It is aimed to achieve measurement accuracy better than 10 nm. There are two electromagnetic modes for WGMs, and then mis-detection of the electromagnetic mode expands measurement errors more than 100 nm, so it is indispensably to distinguish the electromagnetic mode. As theoretical simulation implies, polarization mode of WGMs can be selectively excited by controlling polarization of the incident light in optical coupling. Based on the analysis, it was proofed experimentally that the polarization of WGMs could be classified. As a result, the diameter measurement for a microsphere was performed with measurement error of ± 1 nm.

Abstract: Metal-matrix composites (MMC’s) have considerably enhanced properties including high specific strength; specific modulus, damping capacity and good wear resistance compared to non-reinforced alloys. There has been an increasing interest in composites containing low density and low cost reinforcements. Among various discontinuous dispersions used, fly-ash is one of the most less-expensive and low density reinforcement available in large quantities as solid waste by-product during combustion of coal in Thermal power plants. Alternatively Microspheres derived from the fly ash is also used as reinforcement in Aluminum Metal Matrix Composite to enhance the material properties. Hence, MMC’s uses fly ash and its derivatives used as reinforcement are likely to overcome the cost barrier for wide spread applications in automotive and other industrial applications.Similarly particulate reinforced Aluminum Metal Matrix Composite are gaining importance because of their low cost with advantages like isotropic properties and the possibility of secondary processing facilitating fabrication of secondary components. The Stir casting method based particulate reinforced Aluminum Metal Matrix Composites have higher specific strength, specific modulus and good wear resistance as compared to non-reinforced Al-alloys. They find wide applications in automobile and aerospace because of their excellent combination of physical, mechanical and tribological properties. Primarily because of their high specific strength and stiffness, these composite materials could also be used in Automobiles weight reduction and other applications. In this work a comparative study between Fly ash and Fly ash derived Microsphere base Al-MMC is explained in lucid manner.

Abstract: In this study, a series of composite proton exchange membranes are prepared from sulfonated polydivinyl benzene (sPDVB) microspheres and sulfonated polyphenyl ether (SPPO). The PDVB microsphers and PPO are functionalized by direct sulfonation. The synthesis products are characterized by Fourier Transform Infrared Spectroscopy technique (FT-IR), thermogravimetry analysis (TGA), scanning electron microscope (SEM). The incorporation of sPDVB decreases the water uptake and proton exchange capacity, so the proton conductivity is lower than that of blank SPPO membrane. But the composite membranes still have the excellent conductivity range from 4.88×10^-2 to 6.99×10^-2 Scm^-1.

Abstract: In this study, PCL microsphere has been synthesised using the double emulsion technique and a freeze dry technique. Bovine Serum Albumin (BSA) was added as a model protein and Hydroxyapatite (HA) to enhance osteoconductivity properties of the microsphere. Poly (caprolactone) (PCL)-based microspheres were synthesized and characterized. Microspheres were produced with 5%, 10%, and 15% (w/v) PCL solution (30mL) by dissolving different amounts of PCL in dichloromethane (DCM). Microspheres produced from 5% (w/v) PCL concentration had an average diameter of 100 – 120 μm. Bovine serum albumin (BSA) (0.04% w/v) and 10% w/w of HA powder were added into the microspheres produced from 5% (w/v) PCL concentration. The microsphere was then characterized using different techniques and in vitro release study of BSA was conducted. Prepared microsphere showed good potential for bone tissue engineering.