توجه: محتویات این صفحه به صورت خودکار پردازش شده و مقاله‌های نویسندگانی با تشابه اسمی، همگی در بخش یکسان نمایش داده می‌شوند.
۱An experimental design approach to determine the effect of process parameters on the properties of hydroxyapatite nanoparticles
اطلاعات انتشار: ششمین کنگره بین المللی مهندسی شیمی، سال
تعداد صفحات: ۴
In the present study, an attempt has been made to examine the influence of different process parameters on the properties of HAp nanoparticles, prepared by hydrothermal method. Among the factors that may influence the characteristics of HAp, reaction temperature, pH value, reactant concentration, and presence of urea were evaluated. Using design of experiment (DOE) approach, a random, 24 full factorial experiments was designed to elucidate the effects of the 4 independent process variables on the properties of HAp nanoparticles. According to the results, temperature and pH value were found to be the most significant parameters affecting structural and morphological properties of the Hap nanoparticles. The pH value exerted an adverse effect, while the temperature of hydrothermal treatment had a positive effect. Moreover, concentration of reactants and presence of urea were observed to be important factors affecting the characteristics of HAp nanoparticles.<\div>

۲Experimental Design to Explore the Effective Parameters in Formulation of Dextran Microspheres via Emulsion Crosslinking Reaction
اطلاعات انتشار: ششمین کنگره بین المللی مهندسی شیمی، سال
تعداد صفحات: ۶
The present work describes adoption of a full factorial design–of–experiment methodology to explore the effective parameters on swelling behavior also mean particle size of microspheres prepared via an inverse emulsion technique using Span 80 as a non–ionic surfactant. Microspheres were prepared by chemical crosslinking of internal phase of the emulsion containing dextran using epichlorohydrin as an effective crosslinker for polysaccharides. Particle size and equilibrium swelling ratio of microspheres were selected as output responses upon their influential effects on final application of the produced microspheres as a hemostatic agent or drug carrier. The input parameters in the design were consisted of dextran concentration in the internal phase, molar ratio of the crosslinker to dextran, molar ratio of the reaction catalyst i.e. sodium hydroxide to the crosslinker and finally, surfactant concentration. Using this method; microspheres having uniform granularity with a smooth particle surface were obtained according to scanning electron micrographs. It was found that an increase in polymer concentration in aqueous phase and molar ratio of sodium hydroxide to the crosslinker leads to a significant decline and increase in the mean particle diameter of the microspheres. Moreover; water uptake capacities for microspheres were dependent on both dextran concentration in the aqueous phase and molar ratio of crosslinker\dextran ratios.<\div>

۳Rheological behavior of an injectable scaffold for bone tissue engineering
اطلاعات انتشار: کنفرانس بین المللی فرآورش پلیمرها، سال
تعداد صفحات: ۴
Calcium phosphate ceramics are widely used as bone substitutes, because they are non–toxic, biocompatible and exhibit bioactive behavior. For minimally invasive surgery, homogenously distributing cells and molecular signals throughout the scaffold and directly injection into cavities with irregular shape, in this study the injectable scaffolds were developed. They consist of a biopolymer (hydroxypropyl methylcellulose: HPMC) as matrix and biphasic calcium phosphate (BCP) as filler. Biphasic calcium phosphate consists of nano–sized hyadroxyapatite and nano–sized β–tricalcium phosphate with plate–like morphology.The steady and dynamic rheological properties, turbidity and injectability of the injectable scaffold were investigated. Gelation temperature of HPMC is higher than physiological temperature and dependent on the hydroxylpropyl content and its distribution in HPMC. In order to lower the gelation temperature, Na2SO4 was incorporated into the HPMC solution. The results indicated that the salt decreased the cloud point and gelation temperature of HPMC solution. The shear–thinning behaviour of this system was confirmed using the rheological experiments. No significant difference was observed in the storage modulus and loss modulus with increasing in BCP content, whereas incorporation of Na2SO4 enhanced the modulus. It may be concluded that the specimens with lower BCP phase is more suitable for using as scaffold, because of higher injectability and porosity.<\div>

۴Fabrication of Crosslinked Dextran Microspheres: Screening of Effective Parameters by Plackett–Burman Design–of–Experiments
اطلاعات انتشار: هفتمین کنگره ملی مهندسی شیمی، سال
تعداد صفحات: ۸
Preparation of crosslinked dextran microspheres (CDMs) via crosslinking of the polymer dissolved in internal phase of an inverse emulsion system (W\O) using epichlorohydrin (ECH) was the first objective of this study. Making the fabrication process controllable to obtain microspheresof tunable properties e.g., mean particle size and its distribution was the second objective. APlackett–Burman screening design methodology was employed to investigate the effects of fourkinetics parameters and four process parameters on the final properties of the resulting microspheres including mean particle size and size distribution, equilibrium swelling ratio and specific surface area. Statistical analysis of the results allowed determining of the most influentfactors. Considering the results, dextran concentration was found as the most influential kinetics parameter on the particle size and equilibrium swelling ratio of the obtained CDMs so an increase in the polymer concentration in the aqueous phase leads to a significant increase in the mean particle diameter and decreasing in water uptake capacity of the resulting microspheres<\div>
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