Papers by Keyword: Particle Size Distribution (PSD)

Abstract: In the present paper, monodisperse poly(lactic acid) (PLA) microspheres (MS) containing the enrofloxacin (ENRO), were manufactured by using a modified solid in oil in water (S/O/W) emulsion solvent evaporation method. In order to prepare PLA microspheres with a higher drug loading efficiency by this modified technique, the test of stability and productivity of the primary emulsion was preliminary examined by change species or concentration of the oil-soluble surfactant and the ratio of water and organic solvent. Firstly, enrofloxacin polylactic acid microspheres (ENRO-PLA-MS) were producted, then the morphology and particle size distribution were estimated by scanning electron microscopy (SEM), its encapsulation efficiency and drug loading efficiency were assessed by High performance liquid chromatography (HPLC). In vivo conditions were simulated by an stable release buffer to obtain a detailed release and polymer degradation profile. Consequently, the ENRO-PLA-MS had a denser structure with a smooth, pore-free surface, the preparation of microspheres was simple, the prepared microspheres had excellent controlled drug release characteristics in vitro.

Abstract: Abstract. The effect of particle size distribution, soaking time and sintering temperatures on the densification behaviors of α-Al₂O₃ was investigated. Two different average particle sizes of 36 and 45µ were examined as a variable to analyze the difference in density, radial and axial shrinkage, densification, and microstructure developments. Conventional powder technology route was used to prepare disc-shaped green pellets sintered at 1200-1600°C for different periods. Density measurements for both green and sintered compacts allow for the refinement of processing parameters to obtain dense sintered bodies. Compacts with particle size of 36 µm were noticed to attain higher relative densities as compared with those of 45µm. Densification parameter (∆P) calculations clearly reveals the presence of definite temperatures and times in which limited densification retardation occurred, which permits the suggesting of suitable sintering schemes for this material. Scanning electron micrographs analysis revealed a pore structure assist the observed behaviours for the different schemes.

Abstract: Drug was encapsulated in a novel copolymers of poly(lactic-co-glycolic acid) (PLGA) to investigate the sustained-release formulation of drug loaded polymer microspheres delivery system. Used a modified solid-in-oil-in-water (S/O/W) emulsion solvent evaporation method to prepare microspheres, its morphology and particle size distribution were estimated by scanning electron microscopy (SEM), the profile of in vitro drug release were assessed by High performance liquid chromatography (HPLC). Finally, an stable release buffer was utilized to obtain a detailed drug release profile, which was analyzed by HPLC also. Results showed that the microspheres morphology, encapsulation efficiency and the cumulative drug release efficiency were appropriate for veterinary medicine using. The modified preparation method was simple and optimized, PLGA microspheres with excellent controlled-release characteristics may serve as drug delivery carrier and may prolong the drug sustained-release effect.

Abstract: In order to compare different concentration modes' influence on the nano-silver particle size and morphology,we use three methods to refine nano-silver solution prepared in the lab as:1 centrifugal the solution directly,2 deposit the solution with acetone,3 centrifugal the solution with acetone added.Then test the solution processed with particle size distribution,UV-vis and SEM.The result shows that:the particle sizes of the nano-silver solutions enriched with the three methods are 162.5nm,163.5nm,164nm;the peak of the UV-vis absorption curve are 425nm, 426.5nm,427nm,we can see that different methods of enrichment have less influence on the nano-silver particles' size and morphology. Also the same conclusion can be drawn from SEM test.

Abstract: Fe3O4 ferrofluids with uniform magnetic particles were prepared via improved chemical coprecipation technique. A narrow distribution of 8.6-10.8 nm particle sizes was obtained from the magnetization curve using the free-form-model based on Bayesian inference theory. The mean particle diameter about 9.8 nm is consistent with the XRD and SEM results. The hydrodynamic properties of ferrofluids were investigated with different applied magnetic field and shear rate. The experimental results show that diluted ferrofluid and concentrated ferrofluid are Newtonian-fluid and Bingham-plastic fluid, respectively.

Abstract: Ash samples were collected using eight classifications of atmospheric particulate matter sampler in two temples located in Jiaozuo city. Concentration of particles of different grain size was measured and analyzed. The results indicated that particulate mass concentration was significantly increased in the burning incense air. The maximum concentration of PM_9.0 and PM_2.1 were 9 times than that of the national air quality secondary standard (PM_9.0:0.15mg/m³) and 13.5 times for American standard (PM_2.1:0.065mg/m³), respectively. The size distributions of particles from incense burning overall showed “U” model. Range of size distribution of fine particles concentrated in 1.1~0.43µm, or the total 39.36%~50.14%.

Abstract: On the basis of the principle for the highest filling degree of cement hydrates, it is synthetically considered that a matching connection between hydration of cement, volume increment of solid phase and packing density of cement paste, a calculation method for a connection between cement continuous particle size distribution and strength of hardened cement paste is developed and tested by experiment. Based on above-mentioned analysis, a tentative research on the effect of particle size distribution of cement on strength is carried out.

Abstract: On the basis of the principle for the highest filling degree of cement hydrates, it is synthetically considered that a matching connection between hydration of cement, volume increment of solid phase and packing density of cement paste, a calculation method for a connection between cement continuous particle size distribution and strength of cement paste is developed and tested by experiment. Based on above-mentioned analysis, a tentative research on the effect of particle size distribution of cement on strength is carried out.

Abstract: The paper presents the experimental work regarding the elaboration of some nanocomposite powders with higher SiC content. For the research, three types of mixtures were prepared: 90SiC-10Al, 70SiC-30Al and 60SiC-40Al using mechanical alloying (MA) technique. The MA was carried out in a vario planetary ball mill Pulverisette 4 for 5 hours using different conditions: - the shock mode (the main disk speed 400 rpm and the planets speed -800 rpm); - the friction mode (the main disk speed 400 rpm and the planets speed 800 rpm). The resulting mixtures was investigated by scanning electron microscopie (SEM), X-ray diffraction pattern (RDX), energy dispersive X-ray analysis (EDAX) and particle size distribution. After 5 hours of MA it is observed that the mixture obtained in the friction mode conditions have a homogenous structure and the particle size distribution is better than the particle size distribution of the mixture obtained in the shock mode conditions.

Abstract: Nano-TiO2 coating film is one of the efficient photocatalysts. The particle size distribution of TiO2 has important influence on photocatalytic activity. A new method to determine the particle size distribution of TiO2 nano-film coated on ceramic was developed, by which the images of film acquired by Atom force microscope (AFM) were processed, and TiO2 particles contacted with others were separated and detected. The particle size distributions of two TiO2 nano-films were determined.