MEASUREMENT OF PARTICLE SIZE DISTRIBUTION IN COAL OIL WATER FUELS BY FOUR METHODS

Four methods were used to measure the solids particle size distribution in coal-ol1-water fuel. Both dry and wet screening were utilized for the coarser particles while four different instrumental methods were used to measure the finer particles in diluted liquid suspension. The wet stages of the analyses included both solvent-diluted organic suspensions and measurement after inversion to an aqueous system.

Consistent differences in the absolute values of particle size were observed between the four procedures. Possible reasons for these differences are discussed.     

A STUDY OF THE ACCURACY OF OPTICAL FRAUNHOFER DIFFRACTION SIZE ANALYZER

ABSTRACT

In this paper the discrepance of scattered light between Mie theory and Fraunhofer diffraction is showed at different refractive indexes and sizes of particle. The accuracy of the Malvern particle size analyzer is discussed when it is used to measure small particles and some advice is proposed for its use.     

A Comparison of Particle Size Measuring Instruments using Fine Metal and Ceramic Powders

ABSTRACT

Accurate and repeatable size measurement continues to be a problem in particulate materials processing. Eight different powders commonly employed for the production of high performance metal and ceramic components were used as a basis for examining the effects of powder characteristics on particle size measurement. Several different techniques were used to measure the particle size, including: laser diffraction with the powder dispersed both wet and dry, aerodynamic time-of-flight, electrical zone sensing, dynamic light scattering or photon correlation spectroscopy, and optical image analysis. After reviewing the size data obtained from these vastly different techniques, it is concluded that accuracy is strongly dependent on dispersion of the powder in the carrier fluid. Once adequately dispersed, one obtains analogous particle size information, independent of the instrument.     

Effect of Granulating Method on Particle Size Distribution of Granules and Disintegrated Tablets. I

Abstract

The average particle size and distribution of granules were found to be dependent on the granulating method. The slugging method produced the widest particle size distribution and the largest average particle size, while the microgranulating method produced the narrowest distribution and the smallest average particle size. The average particle size of dexamethasone granules produced by wet granulating, microgranulating and slugging methods, were reduced on compaction by fragmentation. Of the three, the granules prepared by the slugging method, exhibited maximal average size reduction on compaction. On the other hand, the average particle size of sulfadiazine microgranulates and sulfadiazine slugs were enlarged by consolidation during compaction.     

The Use of Fractal Geometry in Pharmaceutical Systems

Abstract

The nature of surface irregularity affects many phenomena including adsorption/desorption, catalysis, crystal growth, drug dissolution and chromatography. Many excellent models have been developed with the oversimplified assumption that all particles are smooth spheres; fractal geometry allows these models to be expanded to irregular surfaces by providing a quantitative means of assessing surface roughness.

An overview of fractal analysis is presented in the following, and the state of the art, as far as pharmaceutical systems are concerned are outlined. Erroneous approaches, as well as the directions pharmaceutical research and technology might take in the area of fractal analysis are suggested.

From a historical perspective, micromeritics (the science of particle size, shape and surface area) were first developed with the assumptions that all particles were smooth spheres.

Much excellent work has been developed with such an oversimplified model. For example, numerous workers have shown that particle flow through an orifice is a function of “particle diameter”, and experiments have most often been carried out on particles as close to spherical as possible, and as monodisperse as possible.

The science of micromeritics, the science of small particles, is the making of Dalla Valle (1943) who coined the term in a book of the same name which describes methods of particle size measurement, mostly used by soil scientists.¹     

The changes in the Mechanic Properties of a direct tableting agent Microcrystalline Cellulose by Precompression

Abstract

In the manufacturing of tablets, direct tableting agents are not only used in direct compression, but are also used in wet granulation and slugging methods. These agents are effective only if their particle size and form is appropriate. However, the precompression, milling and grinding which are applied in the slugging method changes the particular properties of these agents.

In this study, microcrystalline cellulose tablets were prepared both by direct compression and slugging. The consolidation, compressibility and flow properties of the two mixed powders were compared. Finally, it was observed that the compressibility of the mixed powder was influenced negatively by the slugging method.     

Aerosol Synthesis and Characterization of Ultrafine Fullerene Particles

Abstract

Aerosol routes were used to produce fullerene particles in the nanometer size range. Particle formation mechanisms at processing temperatures of 400-700°C were studied by measuring particle number and mass size distributions in the gas phase by a differential mobility analyzer and a low-pressure impactor respectively. Subsequently, the foils of the impactor onto which fullerene particles were collected were examined by HPLC.     

Lysozyme-loaded lipid-polymer hybrid nanoparticles: preparation,characterization and colloidal stability evaluation

Context: Lipid-polymer hybrid nanoparticles (LPNPs) are polymeric nanoparticles enveloped by lipid layers, which have emerged as a potent therapeutic nanocarrier alternative to liposomes and polymeric nanoparticles.

Objective: The aim of this work was to develop, characterize and evaluate LPNPs to deliver a model protein, lysozyme.

Materials and methods: Lysozyme-loaded LPNPs were prepared by using the modified w/o/w double-emulsion-solvent-evaporation method. Poly-?-caprolactone (PCL) was used as polymeric core material and tripalmitin:lechitin mixture was used to form a lipid shell around the LPNPs. LPNPs were evaluated for particle size distribution, zeta potential, morphology, encapsulation efficiency, in vitro drug release, stability and cytotoxicity.

Results: The DLS measurement results showed that the particle size of LPNPs ranged from 58.04?±?1.95?nm to 2009.00?±?0.52?nm. The AFM and TEM images of LPNPs demonstrate that LPNPs are spherical in shape. The protein-loading capacity of LPNPs ranged from 5.81% to 60.32%, depending on the formulation parameters. LPNPs displayed a biphasic drug release pattern with a burst release within 1?h, followed by sustained release afterward. Colloidal stability results of LPNPs in different media showed that particle size and zeta potential values of particles did not change significantly in all media except of FBS 100% for 120?h. Finally, the results of a cellular uptake study showed that LPNPs were significantly taken up by 83.3% in L929 cells.

Conclusion: We concluded that the LPNPs prepared with PCL as polymeric core material and tripalmitin:lechitin mixture as lipid shell should be a promising choice for protein delivery.     

Preparation and evaluation of wet-milled usnic acid nanocrystal suspension for better bioaffinity

Objective: To prepare a new nanosystem of usnic acid (UA) with higher solid content and higher bioavailability.

Methods: Usnic acid nanocrystal suspensions were prepared by the wet milling method, and then the particle size distributions and zeta potential were determined with the Nano ZS90 laser diffraction particle size analyzer. The particles morphology of UA-NCS were observed by scanning electron microscopy method. In addition, solubility and dissolution of UA-NCS in water and phosphate buffer solution were determined in vitro, analyzed by the HPLC method, and then the cellular uptake and pharmacokinetic were carried out on the Caco-2 cells and rats, analyzed by the UPLC-MS/MS method.

Results: Particle size distributions and zeta potential of the UA nanocrystal suspension were 268.7?±?4.0?nm and –23.1?±?0.7?mV, respectively. About the dissolution rate of UA, nanosuspension were significantly faster and higher than common suspension in water and phosphate buffer. And in cellular uptake experiments, the ratio of the maximum amount of drug in unit protein of UA nanosuspension to common suspension was 2.8 times. In rats, oral absorption of nanocrystal UA were superior to the ordinary groups, with the 348% of the maximum concentration and 181% of the AUC after the same dosage administration.

Conclusion: The wet-milling technique was suitable for the preparation of UA nanocrystal suspension, and a new nanosystem of UA with higher solid content and higher bioavailability was achieved.     

Preparation of Essential Oils Loaded Granule by Melt Granulation

Abstract

A comparative study on three granulation methods; melt granulation, fluidized bed granulation and wet granulation was performed to fabricate an essential oils loaded granule. The granule properties such as particle size distribution and the loading efficiency of anethole from fennel and cinnamaldehyde from cinnamon showed that the melt granulation in a high shear mixer was the most feasible method among the three methods.

In melt granulation, the granule particle size was well controlled by polyethylene glycol 6000 (PEG) content of which the optimum value was found to De 20%. Impeller speed and massing time in high shear mixer had small contribution to the particle growth when PEG content was optimized, while PEG particle size had some effect. Finer PEG powder improved the uniformity of granule size. Moreover, the cooling method of the hot mass affected the final granule properties significantly. The cooling with a fluid bed dryer was the best method.

Both of the retention rates of anethole and cinnamaldehyde in the final granule were more than 95% of initial doses irrespective of cooling method. Further, the adoption of a fluid bed dryer enabled very rapid cooling of hot granule with negligible loss of essential oils.     

Coherent detection of enhanced back-scatter from rough surfaces and particle suspensions

Abstract

Coherent detection has been used to measure enhanced back-scatter from a range of rough surfaces and particle suspensions. Strong enhancement peaks have been observed from suspensions of monodisperse spheres at concentrations as low as 0.2%. This low-density regime has not been accessible to earlier (direct-detection) techniques. The possibility of using measurements of the enhancement peak to characterize rough surfaces or to size particles is discussed and the cross-polar returns from a tutorial target are also measured.     

The Effect of the Shape of Powder Grains on the Measured Size Distribution of a Powder

ABSTRACT

Widely used methods of powder size characterization, such as optical diffractometers, image analysis, and sieving, often generate data which differs significantly for studies of the same powder. Newer methods of shape characterization are making it possible to study the reasons for the differences. Current technology in many powder industries are seeking to exploit powders of different shapes and the study of both particle shape and the effect of shape on size distribution measurements is becoming a very active area of powder technology research.     

Evaluation of Batch-To-Batch and Manufacturer-To-Manufacturer Variability in the Physical Properties of Talc and Stearic Acid

Abstract

Magnesium stearate, talc and stearic acid are commonly used as lubricants in tablet formulations. Many studies on the batch-to-batch and manufacturer-to-manufacturer variability in the physical properties and lubricity of magnesium stearate have been reported in the literature. However, very few similar studies have been reported on talc or stearic acid. In this study, physical properties such as particle size, specific surface area, thermal behavior, moisture content, density, and particle shape and morphology of talc and stearic acid batches obtained from several manufacturers were examined. There was little batch-to-batch variability observed in the talc and stearic acid batches obtained from various manufacturers; however, differences in the particle size and specific surface area were seen in the two types of talc, USP samples obtained from one manufacturer. The scanning electron microscope photomicrographs of the stearic acid samples obtained from various manufacturers also showed some differences in the amount of flakes attached to the spherical particles.     

Effects of rotating magnetic field and temperature field on comminution of magnetic particles

Abstract

This study examines the movement patterns and comminution of magnetic Ni particles in pure water in a flask. This flask is on top of an actuator which contains a rotating bar magnet, and is surrounded by circulating water at a constant temperature. A digital camera, a particle size analyzer and a field emission electron microscope were adopted to record the moving patterns, particle size distributions and micrographs of magnetic Ni particles. A thermocouple was employed to measure the temperature of pure water in the flask during Ni particle attrition. The effect of the temperature of the water that circulated around the periphery of the flask and the effect of the shape of the flask were analyzed. This study also investigated the effects of the water‐to‐particulate mass ratio and the placement of a bar magnet with an interface between the positive and negative poles in a bar magnet at an inclination angle on the shrinking and the moving pattern of the Ni particles.     

Melt Granulation in A Laboratory Scale High Shear Mixer

Abstract

The applicability of a 10 litre high shear mixer for melt granulation of dicalcium phosphate and lactose is examined. Polyethylene glycol (PEG) 3000 and 6000 were used as melting binders in concentrations of 15-20% w/w. The effects of binder concentration, massing time, impeller speed, and particle size of the PEG 6000 on granule size, granule size distribution and intragranular porosity are investigated.

It is shown that pellets of a narrow size distribution can be produced by the use of a high impeller speed. Granule size and size distribution are markedly influenced by binder concentration and massing time. The particle size of the PEG has only a minor effect on the granule growth. Granule growth mechanisms by melt granulation are discussed on the basis of the liquid saturations and the amounts of binder liquid and are compared with previous results on wet granulation.     

Feasibility of electrospray deposition for rapid screening of the cocrystal formation and single step,continuous production of pharmaceutical nanococrystals

Objectives: This study employed electrospray deposition (ESD) for simultaneous synthesis and particle engineering of cocrystals.

Significance: Exploring new methods for the efficient production of cocrystals with desired particle properties is an essential demand.

Methods: The possibility of cocrystal formation by ESD was examined for indomethacin-saccharin, indomethacin-nicotinamide, naproxen-nicotinamide, and naproxen-iso-nicotinamide cocrystals. Solutions of the drug and coformer at stoichiometric ratios were sprayed to a high electric field which caused rapid evaporation of the solvent and the formation of fine particles. The phase purity, size, and morphology of products were compared with reference cocrystals. Experiments were performed to evaluate the effects of stoichiometric ratio, concentration and solvent type on the cocrystal formation. Physical stability and dissolution properties of the electrosprayed cocrystals were also compared with reference cocrystals.

Results: ESD was found to be an efficient and rapid method to produce cocrystals for all studied systems other than indomethacin-nicotinamide. Pure cocrystals only formed at a specific drug:coformer ratio. The solvent type has a weak effect on the cocrystal formation and morphology. Electrosprayed cocrystals exhibited nano to micrometer sizes with distinct morphologies with comparable physical stability with reference cocrystals. Nanococrystals of indomethacin-saccharin with a mean size of 219?nm displayed a threefold higher dissolution rate than solvent evaporated cocrystal.

Conclusion: ESD successfully was utilized to produce pure cocrystals of poorly soluble drugs with different morphologies and sizes ranging from nano to micrometer sizes in one step. This study highlighted the usefulness of ESD for simultaneous preparation and particle engineering of pharmaceutical cocrystals.     

Dissolution performance related to particle size distribution for cohpiercially available prednisolone acetate suspensions

Abstract

Dissolution performance for three commercially available parenteral prednisolone acetate suspensions was analyzed using a diffusion based model. Physicochemical properties of the drug and particle size characteristics of the formulation were included in the model as important determinants of dissolution performance.

The model describes the dissolution profile for each formulation with a single characteristic value, the dissolution rate constant. For Products I and II with similar particle size characteristics, the model sufficiently describes the dissolution profile for each formulation but does not provide conclusive evidence about reasons for differences in dissolution performance between the two products. For Product III, the model sufficiently describes the dissolution profile and adequately includes the effect of a bimodal distribution of larger drug particles.

This approach to the analysis of dissolution data for suspension formulations is suggested as being useful during the formulation process to provide for predetermined dissolution characteristics, as an evaluative tool in quality assurance, assurance, and for correlating in-vivo and in-vitro product performance.     

In-Situ Sizing of Powders and Crystals using Phase Doppler Technique

ABSTRACT

ABSTRACT Phase Doppler technique measures the velocity of single particles based on the frequency of oscillations in the light scattered by the particles. The phase shift between two oscillatory signals, collected by two spatially separated detectors, is used as a statistical measure of panicle size. It is shown experimentally that the second and fourth moments of phase shift distribution increase linearly with the second and fourth power of aerodynamic size D of irregular particles, provided that the aspect ratio is small. This allows one to determine the mean and standard deviation of D² in real time without taking a sample. The above result is based on combined measurements using the phase Doppler technique and the aerodynamic particle sizer, and has been consistent for a variety of particles, including alumina, com starch, quartz, and dust. Measurements were also taken to examine the growth and dynamics of crystals, while cooling down a solution of lysine monohydrochloride in a mixture of methanol and water. These data will also be presented and discussed.     

The Production and Evaluation of Orally Administered Insulin Nanoparticles

Abstract

Wet granulation of a hydrophilic sustained release matrix tablet formulation has been studied. A fractional factorial experimental design was employed to identify principal influences and interacting factors from the following : granulation fluid volume, mixing time, mixer speed and inclusion of a wet screening step. Fluid volume and mixing time were primary factors affecting mean granule size. Fines in the granulation were reduced at higher fluid levels and by inclusion of a wet screening operation. There were several interacting factors influencing the particle size properties of the granulation. The factors studied had little influence on the bulk density of the granulation.

The influence of granule mean particle size on flow, compressibility and drug release from finished tablets was evaluated. Flow and compressibility were influenced by granule properties and the data generated suggested that should final tablet properties deteriorate on scale up it may be possible to ameliorate the effect by modification of granulation fluid volume or mixing time or both.

The factors studies had no influence on release of drug from finished tablets.     

Effect of Primary Particle Size on Granule Growth and Endpoint Determination in High Shear Granulators

ABSTRACT

Three different grades of lactose monohydrate having widely differing mean particle sizes, yet similar tap densities, were granulated using a 25L instrumented Fielder mixer. The size distribution, porosity, and pore saturation of the wet granules were determined using a combination of “frozen granule” sieve analysis, mercury pycnometry, and oven drying. The granulating system was found to operate at quasi-steady-state, as granule growth ceased afler liquid addition was terminated. The resultant granule size distributions were strongly dependent on lactose grade. with coarser grades yielding larger granules for identical process conditions. In contrast. the magnitude of the power curves decreased with increasing primary particle size. Both of these observations are consistent with the fact that both the capillary and viscous interparticle fluid forces, which are believed to provide the main interparticle bonding forces in the wet mass, are inversely proportional to particle size.