Single Particle Size Research Articles

The Earth Model Column Collaboratory (EMC<sup>2</sup>) v1.1: an open-source ground-based lidar and radar instrument simulator and subcolumn generator for large-scale models

Abstract. Climate models are essential for our comprehensive understanding of Earth's atmosphere and can provide critical insights on future changes decades ahead. Because of these critical roles, today's climate models are continuously being developed and evaluated using constraining observations and measurements obtained by satellites, airborne, and ground-based instruments. Instrument simulators can provide a bridge between the measured or retrieved quantities and their sampling in models and field observations while considering instrument sensitivity limitations. Here we present the Earth Model Column Collaboratory (EMC2), an open-source ground-based lidar and radar instrument simulator and subcolumn generator, specifically designed for large-scale models, in particular climate models, but also applicable to high-resolution model output. EMC2 provides a flexible framework enabling direct comparison of model output with ground-based observations, including generation of subcolumns that may statistically represent finer model spatial resolutions. In addition, EMC2 emulates ground-based (and air- or space-borne) measurements while remaining faithful to large-scale models' physical assumptions implemented in their cloud or radiation schemes. The simulator uses either single particle or bulk particle size distribution lookup tables, depending on the selected scheme approach, to perform the forward calculations. To facilitate model evaluation, EMC2 also includes three hydrometeor classification methods, namely, radar- and sounding-based cloud and precipitation detection and classification, lidar-based phase classification, and a Cloud Feedback Model Intercomparison Project Observational Simulator Package (COSP) lidar simulator emulator. The software is written in Python, is easy to use, and can be straightforwardly customized for different models, radars, and lidars. Following the description of the logic, functionality, features, and software structure of EMC2, we present a case study of highly supercooled mixed-phase cloud based on measurements from the U.S. Department of Energy Atmospheric Radiation Measurement (ARM) West Antarctic Radiation Experiment (AWARE). We compare observations with the application of EMC2 to outputs from four configurations of the NASA Goddard Institute for Space Studies (GISS) climate model (ModelE3) in single-column model (SCM) mode and from a large-eddy simulation (LES) model. We show that two of the four ModelE3 configurations can form and maintain highly supercooled precipitating cloud for several hours, consistent with observations and LES. While our focus is on one of these ModelE3 configurations, which performed slightly better in this case study, both of these configurations and the LES results post-processed with EMC2 generally provide reasonable agreement with observed lidar and radar variables. As briefly demonstrated here, EMC2 can provide a lightweight and flexible framework for comparing the results of both large-scale and high-resolution models directly with observations, with relatively little overhead and multiple options for achieving consistency with model microphysical or radiation scheme physics.

Experimental Study on Measurement of Drag Coefficient of Sandy Soil Nonlinear Vadose

The seepage characteristics of sand affect its strength, mechanical deformation characteristics, and find safety and stability. The drag coefficient is a dimensionless physical quantity expressing the interaction between fluid and particles, it is also an important parameter that characterizes the permeability of granular soils. Through the seepage test of standard sand with single particle sizes and different grades, analyze the seepage laws of standard sand with different particle sizes in the Darcy and non‐Darcy seepage. The relationship between parameters a and b in the seepage equation and porosity (n), average particle size (d50), nonuniformity coefficient (CU), and curvature coefficient (CC), and their influence degree were studied. An empirical formula for determining the permeability coefficient of standard sand is established. By adding a correction factor and verifying its rationality, the empirical formula of standard sand permeability parameters is finally obtained.

Study on metal/ceramics composite particle by the dry impact blending method for metal additive manufacturing

Metal matrix composites (MMCs) show a unique improvement in metal materials properties such as high specific strength enabling their use in various applications. Additive manufacturing (AM) allows production of complex or customized parts directly from the design without the need for expensive tooling or forms such metal molds and reduces the need for traditional MMCs processing method. Uniform mixed powder is important for producing MMCs. Although ball mills have been used in previous studies, there are problems with the length of the mixing time and the uniformity of the powder, and it is necessary to study the mixing method. Therefore, this study investigated the production of SUS316L/Al2O3 mixed powder for L-PBF using the dry impact blending method that is a method in which material powder is dispersed in a high-speed air flow and the powder is mixed by mechanical impact force. A composite powder was produced with a mixing time of 60-900 seconds for SUS316L powder weight : Al2O3 powder weight were 1 : 0.4 as a theoretical compounding weight and 1 : 0.4 as a theoretical compounding weight of 25%. As a result, it was found that a powder suitable for L-PBF with a single peak particle size distribution was produced in performed for 300 seconds or more with a theoretical composition of 25%.

Effects of particle grading composition of SiC on properties of silicon-bonded SiC porous ceramics

Silicon-bonded silicon carbide (SBSC) porous ceramics had been prepared by mixing two different particle size of SiC powder (coarse and fine) as aggregates for silicon carbide porous ceramics, adding metallic Si as the binder phase and firing at 1450 °C under argon atmosphere. Various combinations of SiC mixtures consisting of two different particle size and packing density were prepared, and the samples were investigated to understand apparent porosity, bending strength, pore size distribution, and microstructure. The result showed that mixing an appropriate proportion of SiC coarse and fine powders could not only improve the pore size distribution of SBSC porous ceramics but also significantly increase the bending strength compared with the single-particle size sample. The system had the highest free packing density when the ratio of coarse to fine SiC size was >2 and the coarse powder content was 60–70 wt%. The optimal bending strength, and apparent porosity were 37.53 MPa and 37.11% respectively when mixing 70 wt% of coarse powder (50.8 μm) and 30 wt% of fine powder (9.5 μm) and sintered at 1450 °C in an argon atmosphere. The material created had 100.3% increased bending strength, and 0.99% decreased porosity compared with the single-particle size sample (50.8 μm).

Твердые липидные наночастицы со стеариновой кислотой, стабилизированные стеаратом иттрия

In this work, we studied the effect of yttrium stearate on the physicochemical properties of dispersions of solid lipid nanoparticles composed of stearic acid stabilized with nonionic surfactants (Tween 60, Span 60). The results showed that an increase in the concentration of yttrium stearate leads to increasing kinetic stability and decreasing the average size of the aggregates. Along with this, the average size of single particles remains practically unchanged and amounts to 35±5 nm.

Effect of Aggregate Size on Recycled Aggregate Concrete under Equivalent Mortar Volume Mix Design

In this paper, the effect of the original aggregate size of the recycled aggregate on the mechanical properties of the recycled aggregate concrete was evaluated. A series of concretes were produced in which natural aggregates, recycled aggregates, and original aggregates in recycled aggregates were matched for a single particle size distribution curve. The replacement levels of recycled aggregate were 25% and 50%, and equivalent mortar volume mix design was applied for recycled aggregate concrete. The results show that the mechanical strength of recycled aggregate concrete increases with increasing original aggregate size. This effect was observed to be greater in concrete using recycled aggregate with a high residual mortar content.

Undersizing of aged African biomass burning aerosol by an ultra-high-sensitivity aerosol spectrometer

Abstract. The ultra-high-sensitivity aerosol spectrometer (UHSAS) differs from most other optical particle spectrometers by using a high-power infrared (IR) laser to detect small particles and reduce the sizing ambiguity due to the non-monotonicity of scattering with particle size. During the NASA ORACLES project (ObseRvations of Aerosols above CLouds and their intEractionS) over the southeast Atlantic Ocean, the UHSAS clearly undersized particles in the biomass burning plume extending from southern Africa. Since the horizontal and vertical extent of the plume was vast, the NASA P-3B research aircraft often flew through a fairly uniform biomass burning plume for periods exceeding 30 min, sufficient time to explore the details of the UHSAS response by selecting single particle sizes with a differential mobility analyzer (DMA) and passing them to the UHSAS. This was essentially an in-flight calibration of the UHSAS using the particles of interest. Two modes of responses appeared. Most particles were undersized by moderate amounts, ranging from not at all for 70 nm aerosols to 15 % for 280 nm particles. Mie scattering calculations show that composition-dependent refractive index of the particles cannot explain the pattern. Heating of brown carbon or tarballs in the beam causing evaporation and shrinking of the particles is the most plausible explanation, though mis-sizing due to non-sphericity cannot be ruled out. A small fraction (10 %–30 %) of the particles were undersized by 25 % to 35 %. Those were apparently the particles containing refractory black carbon. Laboratory calibrations confirm that black carbon is drastically undersized by the UHSAS, because particles heat to their vaporization point and shrink. A simple empirical correction equation was implemented that dramatically improves agreement with DMA distributions between 100 and 500 nm. It raised the median particle diameter by 18 nm, from 163 to 181 nm, during the August 2017 deployment and by smaller amounts during deployments with less intense pollution. Calculated scattering from UHSAS size distributions increased by about 130 %, dramatically improving agreement with scattering measured by nephelometers. The correction is only valid in polluted instances; clean marine boundary layer and free troposphere aerosols behaved more like the calibration spheres. We were unable to directly test the correction between 500 and 1000 nm, though aerodynamic particle sizer (APS) data appear to show that the correction is poor at the largest diameters, which is no surprise as the composition of those particles is likely to be quite different than that of the accumulation mode. This adds to the evidence that UHSAS data must be treated cautiously whenever the aerosol may absorb infrared light. Similar corrections may be required whenever brown carbon aerosol is present.

Enhanced thermal conductivity of epoxy composites by constructing thermal conduction networks via adding hybrid alumina filler

AbstractHigh thermal conductivity of polymer composites could be achieved through constructing 3D continuous thermally conductive networks into polymer composites. Herein, we demonstrate a simple, effective method to optimize the segregated alumina networks by using ternary mixture of alumina particles with different diameter ratios (5.8 μm + 2.6 μm + 0.5 μm) at the fixed total content of 60 wt% via conventional melt blending method. The thermal properties of epoxy composites were investigated as a function of the weight fraction and particle size of alumina particles. The thermal conductivity (TC) values of composites with coarse fillers (13.2 μm) are in agreement with Agari model at high filler loading (57 ~ 67 wt%). And the value of C2 was ~0.949 (close to 1), indicating that the formation of heat conduction paths in the composites. The addition of 60 wt% smaller fillers (2.6 μm) facilitates a higher interaction degree between the polymer/fillers, consequently, leads to a higher Tg of 147.8°C. A high TC of 1.109 W m−1 K−1 is achieved as the ratio of alumina filler with different particle sizes is 7/2/1, corresponding to a TC enhancement of 23%–32% compared to the composites with a single particle size filler. A suitable proportion of hybrid fillers is crucial for constructing three‐dimension continuous network, in which nano‐particles filled between the micro‐particles could increase the particle‐to‐particle connectivity.

Meso-/Microscopic Single Particle Analyses of Vapochromic Solid-State Crystallization in [Pt(CN)2(H2dcbpy)

In this study, the vapochromic behavior of the platinum complex, [Pt(CN)2(H2dcbpy)], was investigated using super-resolution microscopy techniques, that is, structured illumination microscopy and confocal laser microscopy. In [Pt(CN)2(H2dcbpy)], the amorphous-to-crystal transition occurs under the influence of methanol vapor, and the meso-/microscopic solid-state crystallization processes of amorphous single particles can be directly traced by their phosphorescence changes. The time evolutions of three-dimensional vapochromic behaviors demonstrated that when the size of single particles exceeded 10 μm, vapochromism initially manifested along the direction of the position of the MeOH reservoir and that the vapor-induced crystallization initiated at the surface, and subsequently, the crystallization-induced voids enabled vapochromism to advance into the interior of the particles. The findings reported herein provide new insights into the mechanisms underlying solid-state crystallization processes, and a novel strategy to sense organic vapor molecules is proposed.

Knowledge from recent investigations on sloshing motion in a liquid pool with solid particles for severe accident analyses of sodium-cooled fast reactor

Investigations on the molten-pool sloshing behavior are of essential value for improving nuclear safety evaluation of Core Disruptive Accidents (CDA) that would be possibly encountered for Sodium-cooled Fast Reactors (SFR). This paper is aimed at synthesizing the knowledge from our recent studies on molten-pool sloshing behavior with solid particles conducted at the Sun Yat-sen University. To better visualize and clarify the mechanism and characteristics of sloshing induced by local Fuel-Coolant Interaction (FCI), experiments were performed with various parameters by injecting nitrogen gas into a 2-dimensional liquid pool with accumulated solid particles. It was confirmed that under different particle-bed conditions, three representative flow regimes (i.e. the bubble-impulsion dominant, transitional and bed-inertia dominant regimes) are identifiable. Aimed at predicting the regime transitions during sloshing process, a predictive empirical model along with a regime map was proposed on the basis of experiments using single-sized spherical solid particles, and then was extended for covering more complex particle conditions (e.g. non-spherical, mixed-sized and mixed-density spherical particle conditions). To obtain more comprehensive understandings and verify the applicability and reliability of the predictive model under more realistic conditions (e.g. large-scale 3-dimensional condition), further experimental and modeling studies are also being prepared under other more complicated actual conditions.

Charge of clustered microparticles measured in spatial plasma afterglows follows the smallest enclosing sphere model

The plasma-induced charge of non-spherical microparticles is a crucial parameter in complex plasma physics, aerosol science and astrophysics. Yet, the literature describes this charge by two competing models, neither of which has been experimentally verified or refuted. Here we offer experimental proof that the charge on a two-particle cluster (doublet) in the spatial afterglow of a low-pressure plasma equals the charge that would be obtained by the smallest enclosing sphere and that it should therefore not be based on its geometrical capacitance but rather on the capacitance of its smallest enclosing sphere. To support this conclusion, the size, mass and charge of single particles (singlets) and doublets are measured with high precision. The measured ratio between the plasma-afterglow-induced charges on doublets and singlets is compared to both models and shows perfect agreement with the predicted ratio using the capacitance of the smallest enclosing sphere, while being significantly dissimilar to the predicted ratio based on the particle’s geometrical capacitance.

Underestimated health risks: polystyrene micro- and nanoplastics jointly induce intestinal barrier dysfunction by ROS-mediated epithelial cell apoptosis

BackgroundMicro- and nanoplastic pollution has become a global environmental problem. Nanoplastics in the environment are still hard to detect because of analysis technology limitations. It is believed that when microplastics are found in the environment, more undetected nanoplastics are around. The current “microplastic exposure” is in fact the mixture of micro- and nanoplastic exposures. Therefore, the biological interaction between organisms among different sizes of micro- and nanoplastics should not be neglected.ResultsWe measured the biodistribution of three polystyrene (PS) particles (50 nm PS, PS50; 500 nm PS, PS500; 5000 nm PS, PS5000) under single and co-exposure conditions in mice. We explored the underlying mechanisms by investigating the effects on three major components of the intestinal barrier (the mucus layer, tight junctions and the epithelial cells) in four intestine segments (duodenum, jejunum, ileum and colon) of mice. We found that the amounts of both PS500 and PS5000 increased when they were co-exposed with PS50 for 24 h in the mice. These increased amounts were due primarily to the increased permeability in the mouse intestines. We also confirmed there was a combined toxicity of PS50 and PS500 in the mouse intestines. This manifested as the mixture of PS50 and PS500 causing more severe dysfunction of the intestinal barrier than that caused by PS50 or PS500 alone. We found that the combined toxicity of PS micro- and nanoplastics on intestinal barrier dysfunction was caused primarily by reactive oxygen species (ROS)-mediated epithelial cell apoptosis in the mice. These findings were further confirmed by an oxidants or antioxidants pretreatment study. In addition, the combined toxicity of PS micro- and nanoplastics was also found in the mice after a 28-day repeated dose exposure.ConclusionsThere is a combined toxicity of PS50 and PS500 in the mouse intestines, which was caused primarily by ROS-mediated epithelial cell apoptosis in the mice. Considering that most recent studies on PS micro- and nanoplastics have been conducted using a single particle size, the health risks of exposure to PS micro- and nanoplastics on organisms may be underestimated.

Performance evaluation of warm-mixed crumb rubber modified asphalt based on rheological characteristics

In this study, comparative analysis was carried out to investigate the influence of crumb rubber (CR) powder size and warm mix additives (WMA) on the high-temperature properties of warm-mixed crumb rubber (CR-WMA) modified asphalts by temperature and frequency sweep test as well as repeated creep and recovery test. CR-WMA binders were obtained by mixing modifiers including two different types of rubber powder: an individual mesh and a mixed-mesh, and two different WMA additives: viscosity reducer and surfactant. Anti-rutting performance of asphalt binders was determined through several approaches employing various factors including phase angle δ, complex modulus G∗, rutting factor G∗/sinδ, modified rutting factor G∗/(sinδ)9, high failure temperature, equivalent viscosity η', accumulated strain racc, ratio of permanent deformation to total deformation εp/εL, and the Burgers model to determine creep compliance Jand Generalized Voigt GV. The results showed that the combination of CR and WMA exhibited a positive synergistic effect on asphalt’s rheological properties; and CR-WMA modified binder containing mixed-mesh CR powder and surfactant yielded optimum performance. Moreover, analysis of anti-rutting properties indicated that the effect of mixed powder size was found to be more prominent than that of single particle size, the effect of surfactant was better than that of viscosity reducer, and the modification effect of composite modifiers was greater than that of single modifier alone. Furthermore, the permanent deformation occurred continuously with the increase in the number of loadings and the delayed elastic performance was unstable at the beginning of loading progress.

Investigating the effect of grain composition on the erosion around deepwater foundations with a new simplified scour resistance test

Bridges are critical nodes in the transportation system, especially those crossing wide rivers and seas. Once in service, bridge foundations and the surrounding soils will act as a system together and are subjected to erosion caused by the flows. For more than one century, researchers and engineers have made significant efforts to understand the scour process and its mechanisms to protect bridge foundations from failures. Past studies on bridge scour mainly started from treating scour a hydraulic problem and focused on the flow field due to the interactions between flow and structure. Actually, for a given flow condition, the erodibility of bed materials plays an important role for scour initiation and propagation. For this reason, this study developed a new laboratory apparatus, Simplified Scour Resistance Test (SSRT), that can quickly evaluate the erodibility properties of soil samples and assist in identifying the critical conditions for scour initiation and development. It was firstly validated by Toyoura sand samples with a median particle size of 0.17 mm. Additional tests were then conducted on samples sieved to be populated by single-size particles (d = 0.075 mm, 0.25 mm, 0.5 mm, and 2.0 mm, respectively) and four different soil mixtures under different flow conditions. Results indicate that the grain composition has a significant influence on the scour resistance, while the compaction or density has less influence than the grain size. Granular materials with the same median particle size showed very different scour resistance, i.e., well-graded samples have much higher scour resistance than poorly graded ones. Scour characteristics of the mixed soils can be related to the particle size distribution curve. With this new testing apparatus and the results obtained, a correction factor ks is proposed to improve the traditional predictive methods considering soil composition, which overcomes the limitation of traditional scour prediction methods that often only considered the median particle size, D50.

Investigation of the raveling potential of thin friction course (TFC) under freeze–thaw conditions

The thin friction course (TFC), consisting of modified asphalt emulsion, single particle size aggregate, and cement, is usually utilized as a preventive maintenance treatment to address the functional distresses of asphalt pavement. Meanwhile, TFC materials also face harsh environmental and traffic conditions, especially the freeze–thaw conditions in the cold region. To mitigate the freeze–thaw induced raveling distress of TFC, specimens with varying design parameters were evaluated by wet track abrasion test. Besides, the bond strengths of asphalt-aggregate systems with varying design parameters were assessed by the binder bond strength (BBS) test. According to the results, the increased emulsion and moderate styrene butadiene rubber (SBR) dosages are beneficial to improving the raveling resistance of TFC. The addition of cement can reduce the initial aggregate loss of TFC but will also increase the susceptibility under freeze–thaw conditions. In addition, SBR latex can mitigate the freeze–thaw induced damage of pull-off strength tested in the BBS test. Finally, according to correlation analysis, the pull-off strengths of specimens with varying SBR contents only, have the best correlation with the raveling potential of TFC, with a correlation coefficient of 0.715. Thus, the BBS test is capable to distinguish the retention performance of TFC with varying SBR additions.

Effect of particle size distribution on performance and particle kinetics in a centrifugal slurry pump handling multi-size particulate slurry

A significant variation in particle size distribution (PSD) is generally encountered in slurry transportation. The goal of this work is to establish the effect of variation in PSD on the centrifugal slurry pump (CSP) performance and particle kinetics. Computational fluid dynamics (CFD) modeling of a CSP with multi-size particulate slurry has been performed with a sliding mesh approach using the granular Eulerian-Eulerian model. The numerical model is validated with the experimental data of the pump performance for multi-size particulate fly ash slurry. The maximum deviations in the predicted head and efficiency compared to the measured values are of the order of ±2% and ±3.5%, respectively. Simulations with a single representative particle size for multi-size particulate slurry using median and weighted mean diameter approach are also carried out to understand the difference in performance prediction with equi-size and multi-size slurry. The predicted trend of pump performance variation with PSD is linear and non-linear with equi-size and multi-size slurries, respectively. The median and weighted mean approaches showed error in capturing the effect of variation in PSD on pump performance. The variation in PSD significantly affects the flow of particles inside the impeller and casing flow passages due to particle kinetics. Reduction in the intensity of granular pressure, maximum granular viscosity, and the head loss due to friction in impeller and casing flow passages are found with the increase in the fine size particles.

Effects of design parameters and moisture conditions on interface bond strength between thin friction course (TFC) and underlying asphalt pavements

As a new pavement surface treatment, thin friction course (TFC) is mixed with asphalt emulsion, SBR modifier, single particle size basalt aggregate, and cement. In this study, a test apparatus derived from the pure direct shear test was proposed to investigate the effects of design parameters and moisture conditions on the interface strength. Specifically, the design parameters include the tack coat application rates, the material compositions of TFC, and the texture depths of the underlying pavement. Finally, the analysis of variance (ANOVA) was conducted. According to the results, the increased application rate of tack coat and texture depth of underlying pavement could improve the interface bonding performance. The existence of moisture degraded the bond strength between TFC and the underlying pavement. The increased tack coat application rate could mitigate the detrimental effects of moisture conditions on the interface bond strength. In addition, the optimized material compositions of TFC can only strengthen the interface bond strength slightly. To sum up, the tack coat application rate shows the most significant effect on the interface bond strength, followed by the texture depths of the underlying pavement surface and moisture conditions. Furthermore, the interaction of texture depth and tack coat application rate also has a significant influence on interface bonding performance between TFC and the underlying pavement surface.

The Bearing and Breakage Characteristics of Crushed Stone Aggregates in the Bedding Course of Permeable Roads

The current study of permeable roads helps address urban flooding in Chinese cities caused by frequent heavy rainfall and build smart cities with sponge-like functionality. Crushed stone is widely used in constructing the bedding course of permeable roads because it has good water permeability. Experiments on the compaction of crushed stone were carried out by considering the impact of particle size and gradation to examine the strength and particle breakage characteristics of crushed stone and evaluate its use as the aggregate in the bedding course of permeable roads. The compaction process can be divided into two stages, i.e., the preliminary compaction stage and the particle crushing and intensive compaction stage. The latter consists of an alternating cycle of compacting and crushing. The particle size distribution after crushing can be described analogously to the Talbot continuous gradation equation. Single particle size samples are subject to earlier and stronger particle breakage than the mixed particle size sample, which are affected by both compaction level and loading speed. This study has important application value, and it provides experimental support for the study of materials for urban permeable roads.

Rapid tooling through micro additive manufacturing with reinforcement of SiC/Al2O3 in LDPE domestic waste

ABSTRACT This paper reports the in-house development of rapid tooling (RT) through micro additive manufacturing (MAM) with reinforcement of SiC/Al2O3 in primary-recycled low-density polyethylene (LDPE) domestic waste. The reinforcement in recycled LDPE was made in different particulate sizes (µm), namely, single particle size (SPS)/double particle size (DPS)/triple particle size (TPS) and in different weight proportions. The best combinations based upon wear and thermal stability were selected and used for filament wire preparation with twin-screw extruder (TSE). The cylindrical pins as RT reinforced with SiC/Al2O3 were 3D printed on fused deposition modelling (FDM) setup for grinding applications. The outcome of the study highlights that SiC-TPS reinforcement in recycled LDPE matrix resulted in improved wear characteristics of RT prepared as MAM. Further thermographs based upon differential scanning calorimetry (DSC) were plotted to ensure the thermal stability of RT prepared through MAM.

Preparation and characterization of zinc oxide nanoparticles

Zinc oxide nanoparticles are important inorganic particles which receive great interest over the past few years because of the wide nanotechnology application in various fields of material physics and chemistry. The physicochemical properties of resulting ZnO nanoparticles can be controlled by the synthesis route, method of preparation and parameters related to condition processing. In this study, ZnO nanoparticles were successfully synthesized by three different methods namely polyol method, solvothermal method and co-precipitation method. X-ray diffraction (XRD) patterns show that the all resulting ZnO nanoparticles materials which were synthesized by all the three different methods are pure phase with good crystalinity and completely matched the hexagonal-wurzite structure. The presence of a broad and sharp absorption band at around 440 cm-1 in the FTIR spectrum further confirmed the existence of ZnO phase. In polyol method, ZnO nanoparticles were successfully synthesized under hydrothermal condition. Zinc acetate (ZnAc) was dissolved and heated in three different glycol solutions, namely ethylene glycol (EG), diethylene glycol (DEG) and trietyleneglycol (TEG). The effect of different glycol solutions and calcination on the formation of ZnO nanoparticles was investigated. Single-modal narrow particle size distribution of ZnO nanoparticles with average particles size of 2 ± 1 nm, 12 ± 1nm and 13 ± 1 nm were obtained when EG, DEG and TEG were used in the synthesis, respectively. The broadness of the size distribution of the ZnO nanoparticles can be given as EG > DEG >TEG. The specific surface areas of all the resulting materials however show very similar values ranging from 12.2 to 13.5 m2g-1. The low-temperature solvothermal process was employed as the second method to synthesize ZnO nanoparticles. The initial concentration of zinc acetate was controlled and this process is based on the decomposition of zinc acetate and sodium hydroxide (NaOH) in a mixture solution of ethanol and EG. The effect of different zinc acetate concentration and the effect of organic solvent mixtures solution between ethanol and EG can be shown by a single modal narrow particle size distribution with the average size below 25 ± 1 nm. Field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) analysis revealed that less macroscopic agglomeration of ZnO nanoparticles, indicating that the effect of low temperature process in the mixtures solution also contributed to the higher specific surface area of about 40 m2g- 1. Further effect of high calcinations temperature on the physicochemical properties of the resulting ZnO nanoparticles shows more crystalline and pure phase. However, the increasing particles size resulted in the decreasing of specific surface area due to the compact agglomeration of ZnO particles. Lastly, an intermediate zinc oxalate phase was synthesized by oxalate coprecipitation from nearly saturated solution of zinc acetate and 2-propanol of oxalic acid solution. Highly crystallized and pure phase ZnO nanoparticles were successfully synthesized by thermal treatment at 400 to 600 oC for 4 hours. Single-modal narrow particle size distribution of ZnO nanoparticles with the average particles size of 3± 1 nm , 28 ± 1 nm and 25 ± 1 nm are obtained at 400, 500 and 600 oC, respectively. FESEM and TEM also revealed the different surface structure and morphology of ZnO nanoparticles obtained at calcination temperatures. A huge reduction of specific surface area of ZnO nanoparticles from 22.9 m2g-1 to 2.6 m2g-1 was observed when the calcination temperature is increased from 400 to 600 oC. This study verified, a good crystallinity, high purity, small particle size and large specific surface area of ZnO nanoparticles can be obtained using all the methods. The effect of preparation parameters in each method gives the most influence to physichochemical properties of the resulting material.