Up to 20wt% of Mo is added to the CNTs by impregnation method in order to study the particle size effect on catalyst performance. The ratio of Mo/K is fixed at 1.875. The performance of the catalysts was assessed in a micro-reactor at 330oC, 18 bars and H2/CO=2. Catalysts were characterized using different methods including TEM BET, XRD, TPR and H2 chemisorption. According to TPR results smaller particles produce Mo-k oxides which reduced in lower temperature. Increasing Mo particle sizes,based on TEM and H2-Chemisorption results, ethanol selectivity decreased from about 95% to 74% and methanol selectivity increased from 5% to 26%. These results could be attributed to particle size effect on catalytic performance.

Turbulent mixed convection of a nanofluid (water/Al2O3, Φ=.02) has been studied numerically. Two-phase mixture model has been used to investigate the effects of nanoparticles mean diameter on the flow parameters. Nanoparticles distribution at the tube cross section shows that the particles are uniformly dispersed. The non-uniformity of the particles distribution occurs in the case of large nanoparticles and/or high value of the Grashof numbers. The study of particle size effect showed that the effective Nusselt number and turbulent intensity increases with the decreased of particle size.

Particle size effects in metal matrix composites are studied within the continuum theory of mechanism-based strain gradient (CMSG) plasticity. This theory has been quite successful in predicting the size dependent plastic behavior in a wide variety of problems. Two-dimensional (plane-strain) analyses which are carried out on the composite unit cell models with multi-particles of circular shape show that the flow stress of the composites increases by decreasing particle size with a high sensitivity to small particle size. The numerical results are in good agreement with experimental data. Subsequently, the effects of particle shape, orientation and size distribution on the behavior of composites are investigated. Analyses are carried out on the composites containing squared, rectangular and elliptical (with aspect ratio of four) particles of various orientations with respect to the loading direction (i.e. vertical, horizontal and 45 degree inclined directions). The stress inhomogeneity in the matrix, the overall stress-strain curve and the maximum principle stress in the particles of composites with non-circular particles are investigated and compared with those obtained for the composites containing circular particles. The effects of particle size distribution on the behavior of composites are also addressed.

The effect of catalyst particle size on dehydration of methanol to dimethyl ether is investigated using fixed bed and micro-channel reactors at different temperatures and weight hourly space velocities. The experiments were carried out at 290 and 320oC. The space velocities were changed from 10 up to 90h-1 and from 1.22 to 3.65h-1 for fixed bed and micro-channel reactors, respectively. Considering the catalyst particle size effect on dehydration reaction, the particle size was changed from 0.063 to 1mm. Commercial gamma alumina was used as catalyst in all the experiments. The fabricated micro-channel reactor had 40 channels with 1mm diameter and 6 cm length. The channels were sub-coated with alumina and finally were coated with gamma alumina as dehydration catalyst. The results showed that methanol conversions were increased by increasing the temperature and decreasing the particle size of the catalyst. Furthermore, methanol conversion in micro-channel reactor was less than for fixed bed reactor under the similar WHSVs, due to the special geometrical shape of the micro-channels.

In this research, the dependence of CuFe2O4 particle size on the antibacterial properties was investigated. The morphology of the particles was controlled in the presence or lack of sucrose as a novel capping agent. Antibacterial properties of the CuFe2O4 nanoparticles were evaluated using the PVDF or silicon rubber matrices. The crystalline structures of the CuFe2O4 were confirmed by X-ray diffraction (XRD) patterns. The prepared nanostructures were more dissected using field emission scanning electron microscopy (FE-SEM), Fourier transform infrared (FT-IR), and vibrating sample magnetometer (VSM). Eventually, the copper ferrite particle size effect in PVDF and silicone rubber matrices on the antibacterial activity was investigated. The obtained results revealed significant antibacterial properties for the particles. It was found that decreasing particle size would improve antibacterial properties within both polymeric mediums. This research presents novel separable antibacterial magnetic nanostructure suspended in novel media.

TiO2 has drawn much research attention in recent years because of possible applications to environmental purification, selfclean surface and solar energy converters. Anatase and rutile are the two major crystal phases of TiO2. Heat treatment can changecrystal structure and physical properties of TiO2 nanoparticles. In this work, the effect of particles size on anatase-rutile phase transformation due to heat treatment process has been studied. We have used powders with two different sizes with average sizesof 30 nm named as A and 70 nm named as B. The powders were annealed at 400, 500, 600, 700, 800, 900 and 1000°C for 2 h under ambient atmosphere and then cooled slowly. The titania powders obtained have been characterized using transmissionelectron microscopy (TEM), X-ray diffraction (XRD) and BET method. Grain size of samples and morphologic changes after heat treatment were observed by TEM, also particle size effect on the anatase-rutile phase transformation for A and B powders wereinvestigated by XRD technique. Phase transitions from anatase to rutile for powder A occurs at the lower temperature compared to powder B, that is probably due to difference of coarsening mechanism grain size for powder A and B.

In this work، Z-type nano hexagonal ferrites (Ba3Co2Fe24O41) prepared using citrate method. In order to study particle size effects on absorption properties، the ferrite samples were synthesized in two different molar ratios group، CA: EG=6:4، 4:6 with different CA to nitrates molar ratios (Rc). Microstructures and grain size of the ferrites were characterized using XRD and TEM. The results showed ferrite particle sizes are different and 29-79 nm. The radar absorption of ferrite/polymer and ferrite/Ni/polymer composites with synthesized ferrites was measured using vector network analyzer. The nanostructure composite 60% ferrite + 40% polymer with molar ratio CA: EG = 6:4، Rc = 3. 5 and thickness 3 mm had a reflection loss 14 dB in frequency 11. 5 GHz. The reflection loss was increased to 16 dB by adding Ni powder to the composite.

Curcumin is a natural bioactive compound originated from the rhizomes of turmeric (Curcuma longa L.). This study was performed to investigate formic acid and microwave assisted extraction of curcumin from turmeric (Curcuma longa L.). In order to enhance the curcumin extraction, different parameters such as particle size, effect of pretreatment with water, radiation intensity and type of solvent were investigated. For analysis of curcumin content, two methods were developed. Spectrophotometric methods at the stage of optimization and high performance liquid chromatography (HPLC) for determination of the purity of curcumin were used. At particle size of 0.21mm and input power of 100W using acetone as organic solvent, the highest curcumin extraction yields were achieved. The results showed that water is a suitable modifier for the pretreatment of turmeric with microwave irradiation. For purification of curcumin in HPLC analysis, methanol and water were used as co-solvents. Maximum obtained curcumin purity was 82.4%.

A new approach for the synthesis of Prussian blue nanoparticles using the cationic surfactant Cetyl Pyridinium Chloride (CPC) as capping agent has been developed in the present work. Powder X-ray diffraction, transmission electron microscopy, UV–vis absorption spectra, and IR spectroscopy were employed to characterize the product. The TEM image showed that the Prussian blue nanoparticles with diameters of 8-22 nm were obtained. A particle size effect on optical and conductivity properties of the Prussian blue particles was observed. The higher value of activation energy for the nano compound compared to bulk Prussian blue indicates that the ionic conductions are predominant in the nano compound.

During recent years, various types of gels are used to control excess water in oil wells. The exploiting of preformed particle gels (PPG) can be considered as a good candidate to shutoff water channels without blocking of oil bearing zones. In this research, the preformed particle gel has been synthesized from Sulfonated polyacrylamide copolymer and chromium acetate (III) as crosslinker. The analysis of low amplitude oscillatory shear method was used to study on gel strength, complex viscosity, ultimate storage, and viscous modulus. The complex viscosity and ultimate storage modulus of gel were determined about 5919 Pa.s and 35.4 kPa respectively. The core flooding test was used to study of PPG performance in porous media. Further, two different size particle gels (63-106 and 106-188 micron) were applied to investigate the particle size effect on injection pressure and residual resistance factor of water and oil. The disproportionate permeability reduction index of 3.196 and 4.038, and water residual resistance factor of 41.42 and 53.22 were determined for small and large particle gels respectively. The results showed that the gel particle size on the residual resistance factor of water was more effective than the oil residual resistance factor.