Abstract – Polypropylene composites of wood filler were prepared at filler contents of 0 to 60 wt%. The particlesizes of the wood filler investigated were 200, 400, and 800 µm. The polypropylene composites were prepared in an injection moulding machine and the resulting composites were extruded as sheets. Mechanical and thermal properties of the prepared composites were determined. The results showed a significant effect of both wood filler inclusion and particlesizes on tensile strength, impact strength, flexural strength, elongation at breakage and hardness, thermal conductivity, and melting temperate of polypropylene. The increase in wood filler weight % and particles sizes enhanced the tensile strength, impact strength and flexural strength of polypropylene composites. However, the elongation at breakage was observed to decrease with increases in the wood filler content and particle size. Interestingly, careful observation showed that all filler content had same endothermic melting peak at approximately 165 o C.
The flow activation energy of tested feedstocks as a function of shear rate is shown in Figure 4. For both particlesizes, it is visible that the values of E decreased as the shear rate increases, and the activation energy was found to be higher, particularly at bigger particle size. A high value of E indicates a strong temperature-dependence of the feedstocks to the viscosity. Therefore, any small fluctuation of temperature during molding a bigger particle size results in a sudden viscosity change. This could cause defects in the molded parts, such as cracking and distortion due to the undue stress concentration appeared . High activation energy of feedstock F63_31 indicates a drastic viscosity increase upon cooling, and thus feedstock F63_31 required a more accurate temperature control during injection molding. Otherwise, mold temperature distribution will cause non-uniform flow, which induced internal stresses.
The Av nano-delivery systems were constructed according to the procedure shown in Fig. 1. During the process, the water and oil phases were prepared according to the method mentioned above. The oil phase was emulsified in a water phase (oil-in-water emulsion) by high shear emulsi- fication, to prepare a coarse emulsion. The course emulsion was then uniformly dispersed by ultrasonic emulsification. This was followed by stirring, evaporation, and centrifuga- tion of the resulting nanoparticles. The particle size of a delivery system is one of the most important factors affect- ing the release properties and biological activity of the pesti- cide. As shown in Fig. 2, Av nano-delivery systems with particlesizes ranging from 344 to 827 nm were constructed by controlling the synthesis parameters. Particle size is an important parameter for the controlled release properties of pesticides. The particle size of the Av nano-delivery sys- tems could be controlled by changing the PVA/gelatin con- centration ratio. Various Av nano-delivery systems were prepared with sizes ranging from 344 to 827 nm and Av contents ranging from 33.4 to 57.5% (33.4, 44.9, 45.2, and 57.5%), as shown in Fig. 3. All the Av products had smooth surfaces and spherical particle morphologies.
Abstract: This paper presents the result of an investigation on the performance of concrete produced with different coarse aggregate sizes (CAS) and fully immersed in 5% sodium sulfate solution. Concrete mixtures were prepared with two water-to-binder ratios of 0.35 and 0.45 using four different maximum particlesizes (D max ) of coarse aggregates (9.5 mm, 12.5 mm, 19 mm, and 25 mm). Test results indicate that the
Rheological study has been performed experimentally to evaluate the influence of different particlesizes and powder loadings to the rheological properties of SS316L MIM feedstock. The effects of different particle size, powder loading, shear rate and temperature has been investigated using capillary rheometer. The effect of shear rate to the feedstock viscosity was evaluated and result demonstrated that the feedstocks are pseudo-plastic. Their viscosity also shows strong dependence on the shear rate. The activation energy of each feedstock indicates the sensitivity to temperature and shear stress. The moldability index of the feedstock is also significant. The results indicate that the high powder loading feedstock at 64% volumes demonstrate the best rheological properties. The feedstock achieved desirable injection molding characteristics, such as homogeneous, stable, flow behavior index, n < 1, moderate activation energy (E) and high moldability index (a).
Abstract: 7-Ethyl-10-hydroxycamptothecin (SN-38) is a potent broad-spectrum antitumor drug derived from irinotecan hydrochloride (CPT-11). Due to its poor solubility and instability of the active lactone ring, its clinical use is significantly limited. As one of the most promising formulations for poorly water-soluble drugs, nanocrystals have attracted increasing attention. In order to solve these problems and evaluate the antitumor effect of SN-38 in vitro and in vivo, two nanocrystals with markedly different particlesizes were prepared. Dynamic light scattering and transmission electron microscopy were used to investigate the two nanocrystals. The particlesizes of SN-38 nanocrystals A (SN-38/NCs-A) and SN-38 nanocrystals B (SN-38/NCs-B) were 229.5±1.99 and 799.2±14.44 nm, respectively. X-ray powder diffraction analysis showed that the crystalline state of SN-38 did not change in the size reduction process. An accelerated dissolution velocity of SN-38 was achieved by nanocrystals, and release rate of SN-38/NCs-A was significantly faster than that of SN-38/NCs-B. Cellular uptake, cellular cytotoxicity, pharmacokinetics, animal antitumor efficacy, and tissue distribution were subsequently examined. As a result, enhanced intracellular accumulation in HT1080 cells and cytotoxicity on different tumor cells were observed for SN-38/NCs-A compared to that for SN-38/NCs-B and solution. Besides, compared to the SN-38 solution, SN-38/NCs-A had a higher bioavailability after intravenous injection; while the bioavailability of SN-38/NCs-B was even lower than that of the SN-38 solution. SN-38/NCs-A exhibited a significant inhibition of tumor growth compared to SN-38 solution and SN-38/NCs-B in vivo. The antitumor effect of SN-38/NCs-B was stronger than SN-38 solution. The tissue dis- tribution study in tumor-bearing mice showed that nanocrystals could markedly improve the drug accumulation in tumor tissue by the enhanced permeability and retention effect compared to SN-38 solution, and the amount of SN-38 in tumors of SN-38/NCs-A group was much more than that of SN-38/NCs-B group. In conclusion, nanocrystals dramatically enhanced the anticancer efficacy of SN-38 in vitro and in vivo, and the particle size had a significant influence on the dissolution behavior, pharmacokinetic properties, and tumor inhibition of nanocrystals.
A detailed description of the method to retrieve NLC parti- cle sizes from SCIAMACHY limb-scatter observations in the UV spectral range was recently given by Robert et al. (2009). Therefore, only the most important aspects will be briefly discussed here. NLC scattering spectra are extracted for the tangent height with the maximum NLC radiance, which has a mean value of 82.2 km for the SCIAMACHY limb measure- ments considered in this comparison. The NLC ˚ Angstrøm exponents are determined from NLC scattering spectra in the 265–300 nm spectral range. The NLC particlesizes are then retrieved from these ˚ Angstrøm exponents using look-up ta- bles determined with a T-matrix method (Mishchenko and Travis, 1998) for specific particle shapes and size distribu- tions. Unlike the ALOMAR RMR LIDAR measurements, the SCIAMACHY limb observations do not allow the re- trieval of 2 size distribution parameters. Therefore, the width of a normal or log-normal particle size distribution has to be assumed, and then the mean or mode radius can be retrieved. For most results presented here a Gaussian size distribution was used
(a) and (b) appeared when the TEMs were observed by a general SEM. It was confirmed that the surface shape as shown in Figure 5 (d) was due to the partial adsorption of silica with large particlesizes. Therefore, it seems that the problem of discoloration occurred at 200°C, which is a relatively high temperature. TGA analysis was performed to confirm this. Most organic materials decompose at 600°C. We assumed that silica can withstand more than that temperature. The test was performed by heating it to 700°C, starting from the room temperature and at the rate of 20°C/min.
Particle size is expected to have a direct inﬂuence on the features of cast iron splats as well as on in-process oxidation. This size parameter aﬀects the droplet temperature and velocity just before impinging that, in turn, exerts a major inﬂuence on the coating performance through the ﬂattening ratio, the formation of pores, and a reaction layer at the interface. 3,8,9) According to Shi and Dear, 10) the radial spreading velocity of a droplet impacting a solid surface is approximately three times higher than the impact velocity, while the high impact velocity improves the adhesive strength of splats.
Table 1 shows the TEM-EDX analysis for three dif- ferent sets of experiments performed. The variation of Al/Si ratio shows the effect of progressive ablation of the Al foil-Si wafer with an increase in dwell time. This technique could be used to vary the composition of fabricated Al-Si nanooxides by just varying the laser parameters inclusive of dwell time as well as the thick- ness of the aluminum foil. The properties of the mixed oxide nanostructures could be varied by varying the ratio of distribution of both oxides as well as the size of the fabricated nanostructure. To relate the size of the fabricated nanostructure to the laser parameters and to regulate the size of these structures, a particle size distribution study was performed on the fabricated agglomerated particles of powder-diffused aluminosili- cate ceramic. A mechanism is also suggested to predict the size of agglomerated particles of these generated structures.
From the graph of the impact strength against the particlesizes, it can be deduced that HDPE/Alumina composites of 75µm alumina particle size gave higher impact strength and effective toughening for the same weight concentration than 212µm alumina particle size and 212µm alumina particle size gave higher impact strength and effective toughening than 850µm alumina particle size but as the concentration of such small grade particle size increases, the inter-particle distance becomes too small which leads to the large particle agglomerates, from the graphs of impact strength against different concentrations by weight for 75µm, 212µm and 850µm alumina particle. It was deduced that the impact toughness of the various concentrations by weight of HDPE/Alumina composites for 75µm, 212µm and 850µm were determined by measuring the energy absorbed in the fracture of the specimen. The energy absorbed is highest for alumina particle size of 75µm and increases according to the concentration by weight of the particle size. The energy absorbed by 212µm particle size was higher than 850µm particle size and they all increased with increase in the concentration by weight. As the increase in the energy absorbed in proportional to the impact toughness, it follows that the impact toughness increases with decrease particle size and increased particle content. The energy absorbed by 10% 75µm is about 2.5 times higher than the energy absorbed by HDPE, while 10% 212µm absorbed energy exactly twice the energy absorbed by HDPE and 10% 850µm absorbed energy 0.5 times greater than absorbed by HDPE.
Due to less presence of carboxylate anions, sediment of COOH-low was additionally centrifuged, and only suspended solutions were taken for further experiments. In this way, all samples were suspended at PBS but possess different order of carboxyl functionalization amount. Based on the particle size analysis, highly dispersed swCNTs corresponded to greater carboxyl groups and showed a relatively broad spec- trum of particlesizes, with smaller size than COOH-low, whereas less-dispersed swCNTs (COOH-low) showed sharp localization of particlesizes but bigger size than COOH- mid and COOH-max (Figure 1A). Amount of adsorbed plasma proteins revealed the greatest adsorption amount on COOH-max compared to COOH-mid and COOH-low (inset image of Figure 1A). This result was identical to the greatest
Cotton trash. Delta and Pine land (DPl) Company in Scott, MS, provided cotton (DPl 33) that was commercially ginned (without heat) by the Southwestern Cotton Ginning Research Labora- tory in las Cruces, nM. Collected trash samples were separated by hand into specific categories (stem, leaf, hull, and seed). In addition, seeds were delinted by soaking in 70% (w/w) sulfuric acid until fibers were removed from the seeds. Then the seeds were neutralized with 10% sodium biocarbonate, rinsed with water, and allowed to air dry. Following seed delinting, the seed meat was separated from the seed coat. After the samples were separated, a Wiley mill (Scientific Apparatus; Philadelphia, PA) was used to grind each trash sample into smaller particlesizes. Pepper and powder sizes were prepared using 20 (0.841-mm std. diam.) and 80 (0.177-mm std. diam.) meshes, respectively. For all the treatments, trash samples were ground ensuring three replicates of raw, pepper, and powder sizes. Heating was accomplished by using a high perfor- mance Precision Scientific 625S oven (Precision Scientific, Inc.; Winchester, VA) fitted with a digital temperature controller. Following size reductions, trash samples were transferred to open weighing bottles and placed in the oven at desired tempera- tures for 20 min. Trash samples were exposed to temperatures of 22 °C (72 °F) (std. room condition) or 149 °C (300 °F).
In this study, isophthalic acid-zirconium(IV) nanocomposite has been prepared from zirconyl nitrate pentahydrate and potassium iodide, with isophthalic acid, (C 8 H 6 O 4 =Benzene-1,3-dicarboxylic acid) as a ligand, via sonochemical method in ethylene glycol and methanol as solvents. The crystalline tetragonal ZrO 2 has been produced by thermal decomposition of isophthalic acid-zirconium(IV) nanocomposite as precursor. Characterization of nanocomposite was carried out using element analysis, Fourier transfer infrared spectroscopy (FT-IR), X-ray powder diffraction (XRD), scanning electron microscopy (SEM) and thermal gravimetric analysis (TGA) techniques. The results demonstrated that, pure zirconia with particle size of about 49 nm was obtained in which methanol has been used as solvent during the reaction, particlesizes was significantly reduced to about 20 nm, when ethylene glycol used as solvent during formation of the nanocomposite isophthalic acid-zirconium (IV) as precursor.
However, because erythrocytes generally do not have phagocytic capacity, tertiary targeting of nanocarriers entailing delivery to intra-erythrocytic bodies is very difficult. Rather, particles which are small enough in size may pass through the new permeability pathways (NPPs) which occur on infected red blood cell membranes shortly after invasion by the parasite [20, 21, 22, 19]. For this to occur, the sizes need be less than 80 nm in size, which has been determined as the particle size cut off for passage. This may not be achievable in the present case. It is actually much more difficult to achieve such low sizes in conditions in which the drug is not dissolved, due to influences of drug crystals sizes themselves, particularly in co-formulation. To further reduce particle size of anti-malarial drug nanoformulations to attain sizes in the desired range for passage through the NPP, high pressure homogenization may be utilized. However, even after high pressure homogenization, solid lipid nanoparticles produced from Softisan ® by hot pre-emulsion had particlesizes in this range (~ 550 – 700 nm) .
The effects of particlesizes (range 1, 2 and 3) and particle loading (5wt%, 10wt%, 15wt%, 20wt% and 25wt %) on the mechanical properties (tensile and flexural properties), water absorption properties and morphology analysis (optical microscope) of epoxy composites reinforced with cockle shell particles and hybrid epoxy based composite reinforced with cockle shell particles and oil palm fibres were investigated. Pre-chemical treatment of alkaline solution (NaOH) with 5% concentration was used to treat the oil palm fibre prior to the fabrication of composite. Based on the findings, the composite with smaller size and lower loading of cockle shell particle showed higher improvement in mechanical properties. Meanwhile, the hybrid epoxy based composite reinforced with smaller size of cockle shell particle and oil palm fibre showed enhancement in mechanical properties. For water absorption analysis, cockle shell particle-epoxy composites with lower particle loading showed less water uptake.
The 15-year average daily number size-frequency distributions of the peak Harmattan dust concentrations over the period 1996-2011 are shown in Figure 4a. The number frequency distribution curves are plotted on the logarithmic scale with the ordinate dN/dlogD, where N is in the units of particles/cm 3 and D on the abscissa is the particle class mid-point size in micrometer (µm). In all cases like Sunnu , Resch et al.  and Sunnu , the particle number distribution graphs show that the smallest particles are in the highest concentrations. The spectra show a decrease in particle concentration with increasing particle diameters, as is typical of atmospheric aerosols. This observation agrees with related studies of Saharan dust characteristics closer to the source regions . The 15-season average number frequency curve covers roughly five orders of magnitude across the particle (diameter) size of 0.6 µm to 20 µm. The contribution of the Saharan dust to the atmospheric particles by the various particlesizes are shown to lie between 1 and 2 orders of magnitude. The contribution of small particles (D < 2 µm) to the atmospheric dust is about one order of magnitude for Harmattan dust frequency distribution in the Harmattan 1996-2000 while the increment is half for the Harmattan 2001-2011. The average size-frequency distribution of peak Harmattan 2001-2011 shows that particles larger than 2 µm contribute about one and half orders of magnitude to the background while the addition of large particles narrows down to about one order of magnitude for particlesizes around D =20 µm. The overall average frequency distribution for the study period, Harmattan 1996-2011, lies between the small sized aerosol of Harmattan 1996-2000 and the larger sized aerosol of Harmattan 2001-2011.
The material used in this work was sampled in the mining region of “El Barqueño” in the state of Jalisco, and the other in the community of “Loma Larga” in the county of Acatlan, in the state of Hidalgo, both in Mexico. For characterization it was necessary to prepare the sample to particlesizes lower than 100 µm, and then was characterized by the following analytical methods: X – Ray Diffraction; which was done in an ENEL Diffractometer model Equinox 200 located at the University Autonomous of the State of Hidalgo (UASH), Mexico and was also used the database MATCH to index the spectra; quantification of contained elements in sample was carried out by Inductively Coupled Plasma Spectrophotometry with an equipment brand Perkin Elmer model 2100 (located at UASH). At the same way, morphology of samples was obtained using an Scanning Electron Microscopy, brand JEOL model JMS 6300 (located at UASH) with a voltage of 30 keV and equipped with an EDS detector.
The fractal theory is an important component of non-linear science that can be used to examine strictly or statistically self-similar phenomena at the global and local scales. No specific scale is imposed on the study subject and either recursive or iterative algorithms can be used for calculations. This theory has been widely applied to the study of particle size characteristics of soil (Yu et al. 2017). The fractal dimension of the soil particle size distribution char- acterises the composition of soil particlesizes and reflects soil structural characteristics including the degree of uniformity, arrangement of particles, and combination of different textures (Chandra et al. 2011; Hu et al. 2011).
The coir pith available from coir industries are in loose form with high moisture content and at different particlesizes. The moisture content and particle size play an important role during the formation of briquettes. The experiments were conducted with the coir pith obtained from different coir fiber industries located around Tenkasi, Tamilnadu. The coir pith were dried and sieved into different particle size. Certain amount of coir pith from different particlesizes at different moisture level was taken as the sample.