Control Of Particle Size Distribution Research Articles

Optimising the bioreceptivity of porous glass tiles based on colonization by the alga Chlorella vulgaris

Green façades on buildings can mitigate greenhouse gas emissions. An option to obtain green facades is through the natural colonisation of construction materials. This can be achieved by engineering bioreceptive materials. Bioreceptivity is the susceptibility of a material to be colonised by living organisms. The aim of this research was to develop tiles made by sintering granular waste glass that were optimised for bioreceptivity of organisms capable of photosynthesis. Tiles were produced by pressing recycled soda-lime glass with a controlled particle size distribution and sintering compacted samples at temperatures between 680 and 740°C. The primary bioreceptivity of the tiles was evaluated by quantifying colonisation by the algae Chlorella vulgaris (C. vulgaris), which was selected as a model photosynthetic micro-organism. Concentrations of C. vulgaris were measured using chlorophyll-a extraction. Relationships between bioreceptivity and the properties of the porous glass tile, including porosity, sorptivity, translucency and pH are reported. Capillary porosity and water sorptivity were the key factors influencing the bioreceptivity of porous glass. Maximum C. vulgaris growth and colonisation was obtained for tiles sintered at 700°C, with chlorophyll-a concentrations reaching up to 11.1±0.4μg/cm2 of tile. Bioreceptivity was positively correlated with sorptivity and porosity and negatively correlated with light transmittance. The research demonstrates that the microstructure of porous glass, determined by the processing conditions, significantly influences bioreceptivity. Porous glass tiles with high bioreceptivity that are colonised by photosynthetic algae have the potential to form carbon-negative façades for buildings and green infrastructure.

Nano Alumina: A Review of the Powder Synthesis Method

Nanocrystalline ceramic materials are those with size smaller than 100 nm which have great importance in the field of nanotechnology. Nano-sized materials have properties superior to bulk materials, including improved surface area-to-volume ratio and high strength and toughness. This review paper presents an outline of the preparation of nano alumina by different methods such as sol-gel, combustion, precipitation, hydrothermal and leaching from kaolin. Nano alumina has a broad range of applications, so development of cost-effective processing routes for synthesis of nano alumina is the most prominent industrial challenge. These methods highlight the benefit of controlled particle size distribution with less agglomeration, improved morphology and controlled generation of pure nano alumina phase during the synthesis process. More research should be carried out to discover processing conditions that advance these goals.

Use of continuous solid-phase synthesis to obtain phosphors based on strontium aluminate

The effect of conditions of continuous solid-phase synthesis on particle size distribution of nanostructured powders of strontium aluminate was studied. It was shown that continuous solid-phase synthesis allows for: synthesis of strontium aluminate in the form of nanostructured powders with controlled particle size distribution directly during its synthesis; in the presence of a liquid phase strontium aluminate is synthesized with a high level of monophasity. It was shown that in order to optimize the illuminating parameters of phosphors based on strontium aluminate, it is advisable to use continuous solid-phase synthesis.

Adaptive Fault-Tolerant Stochastic Shape Control With Application to Particle Distribution Control

This paper investigates the fault-tolerant shape control (FTSC) problem for stochastic distribution systems. For this problem, in addition to measurable input signals, it is assumed that the distribution function of the system output can be evaluated so that it is available. It is also assumed that the system is subject to actuator faults. In this case, the main control objective is for the output of the stochastic distribution system to track a given target distribution even in the presence of actuator faults. By estimating these actuator faults, an effective FTSC strategy is proposed, which consists of a normal control law and an adaptive compensation control law. The former can track the given output distribution with an optimized performance index in the fault-free case, while the latter can automatically reduce (or even eliminate) the adverse effects caused by the actuator faults. The proposed method can be applied to tracking control of output probability density functions. To demonstrate the effectiveness of the proposed scheme, simulation is performed on one numerical example with satisfactory results obtained. In addition, a practical example of soil particle gradation control in geotechnical applications is given in this paper, and the results show that the proposed fault-tolerant scheme is applicable to practical particle size distribution control.

Self-assembly of zein microspheres with controllable particle size and narrow distribution using a novel built-in ultrasonic dialysis process

Zein microspheres with controllable particle size and narrow size distribution were self-assembled using a novel built-in ultrasonic dialysis process (BUDP). The effects of different variables on the microstructures of obtained zein particles were investigated using an OA16 (45) orthogonal experimental design. The results showed that zein particles prepared by the BUDP possessed a spherical morphology with mean particle size (Dp50) from 431.2±69.6nm to 2335±406.1nm under different process parameters. Zein microspheres prepared at optimized conditions presented much smaller particle size and narrower size distribution (Dp50=398.2±41.3nm) than those obtained without ultrasound (Dp50=1776±1181.1nm). FT-IR, 1H NMR, XRD, TG and DSC characterization results showed that the chemical structure, crystal structure and thermal behavior of the zein microspheres obtained by BUDP were similar with raw zein and that prepared without ultrasound. The ultrasound power and zein concentration were the most important process parameters affecting particle formation. The formation mechanisms of zein microspheres and the influence mechanisms of the operating parameters were discussed in detail. Also, a semi-empirical model was developed for predicting particle size. Furthermore, curcumin was encapsulated into zein microspheres using BUDP, and curcumin-loaded zein microspheres sustained curcumin release rate successfully in vitro.

Efficient encapsulation of proteins in submicro liposomes using a supercritical fluid assisted continuous process

Recently a new supercritical assisted process was proposed in the literature for the production of liposomes, called Supercritical Assisted Liposome formation (SuperLip) process. It has been demonstrated that, using this new process, it is possible to produce liposomes based on phosphatidylcholine (PC) with a controlled particle size distribution. Also a preliminary encapsulation test revealed a high encapsulation efficiency of bovine serum albumin (BSA), used as model hydrophilic compound.Being convinced of the great potential of the SuperLip process, in this work it has been studied the possibility of producing liposomes with a different composition of the bilayer membrane using the SuperLip process. Phosphatidylcholine (PC) and phosphatidylglycerol (PG) were used in a mixture and the production of liposomes was tested under different operative conditions: pressure, temperature and lipid composition. Results obtained using only PC and PC/PG mixture have been systematically compared. Furthermore a deepened study about the possibility to encapsulate BSA as model compound was performed. SuperLip experiments using different amount of BSA dissolved in the water internal phase were performed and the relative encapsulation efficiencies of produced liposomes were estimated. A comparison of encapsulation efficiency of liposomes produced, at the same BSA loadings, using a conventional preparation process (Bangham method) was also performed. The stability of entrapped protein was investigated.Sub-micrometric liposomes of soybean phosphatidylcholine (PC) of different size and distribution ranging between 250±58nm and 330±82nm were successfully produced. When using PG coupled with PC, larger liposomes were produced, ranging between 280±70nm and 350±101nm. Both PC and PC/PG liposomes were stable over one month, thanks to the large and negative surface charge (zeta potential ranging between −20mV and −30mV).For the drug encapsulation tests different BSA theoretical loadings with respect to the lipid amount (10–30–60%, w/w) were tested. In the case of SuperLip process, very high encapsulation efficiencies (92–98%) were obtained at all the drug loadings; lower encapsulation efficiencies were instead obtained using the Bangham method (2–57%). Results reported in this work demonstrated that using SuperLip process, the protein contained in the water phase can be efficiently entrapped without damaging the protein structure as confirmed by FTIR analysis of processed BSA.

Particle Size Distribution and yield control in continuous Plug Flow Crystallizers with recycle

Plug Flow Crystallizers (PFCs) are one of the most widely employed forms of continuous crystallizers. PFCs are usually selected for processes with fast kinetics and short residence times. One key limitation of PFCs is that normally they do not operate at equilibrium conditions as a consequence of the short residence times. Thus, the resultant yield from PFCs is generally less than that of the equivalent batch process.Recycling the mother liquor back through the PFC is one approach, which can potentially be used in order to mitigate against this drawback, allowing for an amelioration in the continuous process yield.In the present work, the effects of introducing a recycle stream and adjusting critical recycling parameters, namely recycling ratio and axial extraction position, on an idealized PFC are examined. Particular attention is focused on the resultant volume average size of particles d4,3, and the process yield η. The influence of feed velocity along with the recycle parameters on the maximum and minimum yield and size of crystals achievable is also investigated.The proposed continuous PFC, as conceptualized and modeled with recycle, facilitates practical application in an industrial setting, allowing for augmented continuous process yields, whilst furthermore facilitating PSD control.

Optimization of a Crystallization Process for Orantinib Active Pharmaceutical Ingredient by Design of Experiment To Control Residual Solvent Amount and Particle Size Distribution

Orantinib is obtained as a final active pharmaceutical ingredient (API) through crystallization by neutralizing the potassium salt of orantinib in a mixed solvent of isopropyl alcohol (IPA) and H2O. However, the amount of residual IPA in the orantinib API varies, and the neutralizing crystallization makes control of the particle size distribution of the orantinib API difficult. We performed 36 experiments using the design of experiment approach to screen and optimize the process parameters for an orantinib API crystallization process. The screening clarified the strength and trends in the effects of various parameters on the amount of residual IPA and the particle size, and the temperature and solvent ratio were critical process parameters. Next, we constructed a design space for the temperature and solvent ratio by optimizing the process parameters, prepared a response surface model, and calculated the optimal conditions under which both the amount of residual IPA and the particle size distribution could...

Investigation of ouzo effect colloid formation via organosilica nanoparticles

The ouzo effect is a rapid route to nanoparticle formation through nanoprecipitation via the addition of a poor solvent to supersaturate a polymer solution. Currently, there are differing opinions on the mechanism of particle formation: nucleation and growth, nucleation and aggregation, or spinodal decomposition. To elucidate the mechanism, various concentrations of organosilica were added as artificial nucleation embryos to poly(methyl methacrylate)-tetrahydrofuran solutions prior to nanoprecipitation. Particle size distribution was monitored via dynamic light scattering, while the morphology and organic content of select samples were further characterized via transmission electron microscopy and thermal gravimetric analysis, respectively. The data establishes that spinodal decomposition was the mechanism of particle formation and that silica can be used as an additive for particle size distribution control during ouzo effect particle formation.

A new method to synthesize high solid content waterborne polyurethanes by strict control of bimodal particle size distribution

Abstract A new method named two-step emulsification process was developed to synthesize high solid content waterborne polyurethanes by strict control of the bimodal particle size distribution. In the first step, a series of 40% solid content polyester-based (WPU-1) with low content of hydrophilic group and large particle size were firstly synthesized. In the second step, polyether-based prepolymers (WPU-2 prepolymers) with high content of hydrophilic group were firstly prepared and WPU-1 emulsions were used to emulsify WPU-2 prepolymers to obtain the final emulsions with high solid content (WPU-3). The particle size of WPU-3 present bimodal distribution and the diameter ratio and volume percentage of large particles to small particles in WPU-3 were able to be strictly controlled by this method. The viscosity of WPU-3 with 55% solid content was only 489.1 mPa s −1 when the diameter ratio of large particles to small particles was 9.2 and the volume percentage of large particles was 74%.

Crosslinking network structure effects on particle coagulation in the emulsion polymerization of styrene in methanol solution

This work is an extension of previous research results reported by our team (Colloid Polym Sci 292:519–525; 1347–1353), where how to control particle size distribution by adjusting particle coagulation has been investigated. There is limitation in previous studies, that is, the particles taking part in coagulation only possess a linear structure. However, the crosslinking network structure is necessary to many fields, such as rubber and plastic modifier. Thus, it is very significant to investigate the effect of the crosslinking network structure on particle coagulation for understanding the nature of particle coagulation and controlling particle size distribution. In this manuscript, dihydrodicyclopentadienyl acrylate (DCPA) is chosen as a crosslinker to copolymerize with styrene to promote particle structure shift from the linear to the crosslinking network structure and to investigate further the coagulation behavior of the particles with the crosslinking network structure. Experimental results are explained by the collision frequency of particles and stability dependence of the particle structure.

Particle Nucleation and Growth in the Emulsion Polymerization of Styrene: Effect of Monomer/Water Ratio and Electrolyte Concentration

This work is an extension of previous research results reported by our team (Colloid and Polymer Science 2013, 291: 2385-2398), where large scale and high solid content latexes of poly(n-butyl acrylate) were obtained with the particle coagulation method induced by the electrolyte. However, how to prepare controlled particle size distribution polymer latex has not been studied. Thus, in this study, the effect of the monomer/water ratios and electrolyte concentrations on particle formation and growth methods were studied by following the tracks of the evolutions of particle size, number and distribution as a function of reaction time or conversion. Experimental results showed that the length of time that particle nucleation occurred increased with increasing monomer charged for the systems without electrolyte. A point worthy of attention here is that homogeneous nucleation may occur at high monomer concentrations (30/70, 40/60). However, electrolyte added could be made the nucleation mechanism shift from micellar/homogeneous nucleation to micelle /coagulation nucleation. As a result, the final particle size distribution can be controlled by adding an appropriate electrolyte to regulate the nucleation mechanism. Spherical and uniformly sized particles could be obtained when electrolyte concentration is between 0.2 wt% and 0.4 wt% for water at the high monomer/water ratio (40/60). The effects of electrolyte concentration on nucleation mechanism mainly were expressed by decreasing the solubility of the monomer and interparticle potential, and then preventing homogeneous nucleation and enhancing particle coagulation.

Ball milling assisted hydrothermal synthesis of ZrO2 nanopowders

The formation of ZrO2 nanopowders under various hydrothermal conditions such as temperature, time, autoclave rotation speed, heating rate and particularly assistance of ball milling during reaction was investigated. Full ZrO2 formation (with monoclinic phase) from zirconium solution was completed at shorter times with increasing temperature such as after 4h at 150°C, 2h at 175°C and less than 2h at 200°C. Crystallite size increased from 2.9 to 4nm with increasing reaction temperature from 125°C to 200°C, respectively. Ball milling assisted hydrothermal runs were performed to understand the effect of mechanical force on phase formation, crystallinity and particle size distribution. Monoclinic ZrO2 was formed in both milled and non-milled runs when zirconium solution was used. Mean particle size for the 2M solution was measured to be 94nm for the milled and 117nm for the non-milled powders. However, when amorphous aqueous zirconia gels (precipitated at pH 5.8) were used, tetragonal phase was also formed in addition to monoclinic phase. Mean particle size was measured to be 0.7μm (d90≅1.3μm) for the milled and 7.9μm (d90≅13μm) for the non-milled powders. Ball milling during hydrothermal reactions of both zirconium solution and aqueous zirconium gel resulted in smaller crystallite size and mean particle size and, at the same time, effectively controlled particle size distribution (or agglomeration) of nanopowders.

Characterization of Gas Atomized Ni-Mn-Ga Powders

Gas atomization is a well-known process for obtaining high quality metallic powders. It produces spherical high-density particles with a controllable particle size distribution. We used gas atomization to obtain two different Ni-Mn-Ga powders and investigated their microstructure, transformation temperatures and magnetic properties as well as the effects of heat treatment on those. The phase and magnetic transformation temperatures of the powders were considerably lower as compared to similar conventionally prepared alloys. Nevertheless, heat treatment of the atomized powder was found to recover the magnetic properties of the materials, probably by releasing the residual strains generated by the rapid solidification during the gas atomization process. Sintering of powders seemed to start at a significantly lower temperature when compared to the powder prepared by ball milling of bulk Ni-Mn-Ga-alloys.

Production of Silicon Particles for High-Capacity Anode Material Yielding Outstanding Production Capacity

The application of silicon as an anode material for lithium-ion batteries requires cost-effective fabrication routes and facile processing of the material. Here we present the production and characterization of silicon particles prepared using a silane-based free-space reactor, allowing control of particle size distribution and crystallinity and an outstanding production capacity. The synthesized silicon particles were chemically characterized, prepared as anode material electrodes and electrochemically characterized. The effect of active material loading and electrolyte additives was studied.

Preparation of uniform poly-caprolactone Microparticles by membrane emulsification/solvent diffusion process

Over the last decade, the use of polycaprolactone has attracted much interest in drug delivery compared to biodegradable polyesters derived from lactic and glycolic acids. The methodologies commonly used for the preparation of polycaprolactone microparticles are associated with many problems regarding the control of particle size and size distribution and particles morphology. Membrane emulsification/solvent diffusion processes offer great potentials in manufacturing particles. In this work, polycaprolactone microparticles with mean diameter of 20μm, spherical shape and smooth surface have been successfully produced using the emulsification/solvent diffusion method. The fluid-dynamic and chemical parameters have been optimized to produce uniform particles with a span value of 0.5. The effect of process parameters controlling the solvent diffusion on the shape and surface morphology has also been investigated. The use of microporous membranes allowed the simultaneous particle size and size distribution control during the emulsification step. Also, the solvent diffusion permitted easy control of the size and morphology of particles during the solidification of polymer within the droplets.

Estimation of particle size distribution on an industrial conveyor belt using image analysis and neural networks

Monitoring and controlling particle size distribution in crushing and grinding circuits are essential for improved energy efficiency and metallurgical performance. Machine vision is probably the most suitable approach for on-line particle size estimation because it is robust, cost-effective and non-intrusive. In the present study, size distribution of particles in crushing circuit of a copper concentrator was estimated using image processing and neural network techniques. Several images were taken from material on a conveyor belt and processed for particle identification and segmentation. A number of the most commonly used size features were extracted from the segmented images and their potential to estimate the actual particle size, represented by sieve size analysis, was evaluated. The results showed that there were substantial differences between size distributions obtained from various size measures. Maximum inscribed disk was found to be the most effective feature for particle size description. Finally, the particle size distribution of material on the conveyor belt was precisely estimated by Principal Component Analysis (PCA) and neural network techniques. The proposed soft sensors can be used for real time measurement of particle size distribution in the industrial operations instead of sophisticated and expensive instruments.

A comparative study of top-down and bottom-up approaches for the preparation of nanosuspensions of glipizide

Glipizide nanosuspensions were prepared by both liquid antisolvent precipitation and media milling technique using bead mill. From this study it was concluded that ratio of polymer to drug, milling time and milling speed played significant role in controlling the zeta potential of nanosuspension prepared by media milling whereas, milling time and milling speed were considered to be significant factors for controlling particle size distribution d (90) of nanosuspension. In the bottom up process ratio of surfactant to drug and speed of mixing played a significant role in controlling the zeta potential of glipizide whereas ratio of polymer to drug and speed of mixing were considered to be the significant factors that affect the particle size distribution d (90) of nanosuspension. An increase in particle size distribution was observed with the optimized nanosuspension prepared by liquid antisolvent precipitation method when tested under accelerated conditions (40°C at 75% RH for 6months) as compared to media milling method. The X-ray diffraction data shows no form conversion of the drug due to processing parameters involved in the production of nanosuspension. The formulated nanosuspension has shown a faster dissolution profile (98.97 using bottom up and 96.44% using top down method in 10min), relative to that of pure glipizide (20.17% in 10min), mainly due to the formation of nanosized particles.

Saponins: A Renewable and Biodegradable Surfactant From Its Microwave-Assisted Extraction to the Synthesis of Monodisperse Lattices

Synthetic surfactants are widely used in emulsion polymerization, but it is increasingly desirable to replace them with naturally derived molecules with a reduced environmental burden. This study demonstrates the use of saponins as biodegradable and renewable surfactants for emulsion polymerization. This chemical has been extracted from soapnuts by microwave assisted extraction and characterized in terms of surfactant properties prior to emulsion polymerization. The results in terms of particle size distribution and morphology control have been compared to those obtained with classical nonionic (NP40) or anionic (SDS) industrial surfactants. Microwave-extracted saponins were able to lead to latexes as stable as standard PS latex, as shown by the CMC and CCC measurements. The saponin-stabilized PS particles have been characterized in terms of particle size and distribution by Dynamic Light Scattering and Asymmetrical Flow Field Flow Fractionation. Monomodal and monodispersed particles ranging from 250 to 480 nm in terms of diameter with a particle size distribution below 1.03 have been synthesized.

Synthesis of high solid content waterborne polyurethanes with controllable bimodal particle size distribution

ABSTRACTA series of waterborne polyurethane dispersions were synthesized by one‐pot reaction and step‐wise reaction, respectively. The effects of synthetic methods and DMPA content on the particle size distribution (PSD), solid contents and viscosity were studied by laser particle size analyzer, Brookfield viscometer and TEM analysis. High solid content and low viscosity waterborne polyurethanes (WPUs) with controllable bimodal PSD were prepared by one‐pot reaction using 2,2‐dimethylol propionic acid (DMPA) as the only self‐emulsifier. Meanwhile, 40% solid content WPUs with unimodal PSD were obtained by step‐wise reaction at the same formula. With the increment of DMPA content, the ratio of large particles to small particles decreased and two peaks of the particle size finally became one peak by one‐pot reaction while the PSD remained unimodal by step‐wise reaction. The reason leading to the difference of PSD between one‐pot reaction and step‐wise reaction was analyzed and the relationships among PSD, viscosity and solid content were discussed. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40420.