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PubMed1978

Sheabutter V: effect of particle size on release of medicament from ointment.

An ointment prepared from fat (sheabutter) obtainable from an indigenous (African) fruit released medicaments faster than either of the two ointment bases recommended by the British Pharmacopoeia. Reduction in particle size of crystalline medicaments incorporated in ointments increased surface area and transfer from the ointment to the substrate, possibly due to greater dissolution in the base, and, therefore, increased the availability of medicament at the ointment-substrate interface.

Agar↗

PubMed1993

Dosing efficiency and particle-size characteristics of pressurized metered-dose inhaler aerosols in narrow catheters.

An experimental in vitro model was used to determine the effects of intraluminal catheter diameter and length on the delivered dose and particle-size characteristics of salbutamol (albuterol) aerosol delivered by metered dose inhaler (MDI) (Ventolin, 100 micrograms per puff). The dose of aerosolized drug that exited a 16-cm-long tracheal tube with an inner diameter (ID) of 6 mm was compared with that from 4 catheters of differing diameters and lengths that were inserted individually into the tracheal tube. The salbutamol MDI canister was actuated ten times into each delivery system, and the effluent aerosol was trapped onto a filter. The filtrate was dissolved in methanol, and the salbutamol concentration was determined using high-performance liquid chromatography. For the 3 22-cm-long catheters, the delivered dose (mean +/- SD) of salbutamol per actuation for the 22-standard wire gauge (SWG) catheter was 97.5 +/- 3.9 micrograms, which was similar to that for the 19-SWG catheter (102.3 +/- 2.5 micrograms) but was significantly less than that for the 14-SWG catheter (108.2 +/- 4.2 micrograms) (p < 0.05). These delivered doses exceeded those of the 6.0-mm-ID tracheal tube alone (2.33 +/- 0.76 micrograms) and the 13-cm-long 19-SWG catheter (2.17 +/- 0.29 micrograms) (p < 0.001). In a second experiment using a cascade impactor, the distribution of aerosol particle diameters that exited the 6-mm-ID tracheal tube was compared with that exiting a 13-cm-long 19-SWG catheter that extended halfway down the tracheal tube and with that exiting a 22-cm-long 19-SWG catheter inserted into the distal end of the 6-mm-ID tracheal tube. The mass median aerodynamic diameter (mean +/- SD) of the salbutamol aerosols delivered through both the 6.0-mm-ID tracheal tube (1.1 +/- 0.1 microns) and that of the 13-cm-long 19-SWG catheter (1.2 +/- 0.2 microns) were significantly less than that delivered through the 22-cm-long 19-SWG catheter (2.0 +/- 0.1 microns) (p < 0.05). The authors conclude that delivery of respirable aerosol can occur through narrow catheters that function as extended nozzles for MDIs. Optimal dosing will be obtained when the catheter extends the full length of the tracheal tube.

Aerosols↗

PubMed2000

Targeting aerosol deposition in patients with cystic fibrosis: effects of alterations in particle size and inspiratory flow rate.

STUDY OBJECTIVE: To determine if aerosolized medications can be targeted to deposit in the smaller, peripheral airways or the larger, central airways of adult cystic fibrosis (CF) patients by varying particle size and inspiratory flow rate. DESIGN: Randomized clinical trial. SETTING: Outpatient research laboratory. PATIENTS: Nine adult patients with CF. INTERVENTIONS: Patients inhaled an aerosol comprised of 3.68+/-0.04 microm saline solution droplets (two visits) or 1.01+/- 0.2 microm saline solution droplets (two visits) for 30 s, starting from functional residual capacity and breathing at a slow or faster inspiratory flow rate. On all visits, the saline solution was admixed with the radioisotope (99m)Tc. Immediately after inhalation, a gamma camera recorded the deposition pattern of the radioaerosol in the lungs. Deposition images were analyzed in terms of the inner:outer zone (I:O) ratio, a measure of deposition in an inner zone (large, central airways) vs. an outer zone (small airways and alveoli). MEASUREMENTS AND RESULTS: For the 3.68-microm aerosol, I:O ratios averaged 2.29+/-1.45 and 2.54+/-1.48 (p>0.05), indicating that aerosol distribution within the lungs was unchanged while breathing at 12+/-2 L/min vs. 31+/-5 L/min, respectively. For the 1.01-microm aerosol, I:O ratios averaged 2.09+/-0.96 and 3.19+/-1.95 (p<0.05), indicating that deposition was predominantly in the smaller airways while breathing at 18+/-5 L/min and in the larger airways while breathing at 38+/-8 L/min, respectively. CONCLUSIONS: These results suggest that the targeted delivery of an aerosol to the smaller, peripheral airways or the larger, central airways of adult CF patients may be achieved by generating an aerosol comprised of approximately 1.0-microm particles and inspiring from functional residual capacity at approximately 18 L/min and approximately 38 L/min, respectively.

Administration, Inhalation↗

PubMed2006

Effect of particle size and compression force on compaction behavior and derived mathematical parameters of compressibility.

PURPOSE: To analyze the influence of inherent densification and deformation properties of paracetamol on the mathematical parameters derived from Heckel, Walker, Kawakita, and Adams equations and to correlate these with single particle nominal fracture strength and bulk compression parameters using confined compression on a fully instrumented rotary tablet press. MATERIALS AND METHODS: Force-displacement data were captured during in-die compression for four different particle size fractions (150-250, 300-450, 500-650, and 700-1,000 microm) of paracetamol each at compression force of 5.2, 8.6, and 17.3 kN. Nominal single particle fracture strength was obtained by micro tensile testing. RESULTS: Apparent mean yield pressure (Py) from Heckel analysis was significantly affected by the applied pressure, and was influenced by elastic energy and Young's modulus. The single particle fracture strength correlated to parameters obtained from Heckel, Walker, Kawakita, and Adams equations. Results obtained from bulk compression and single particle measurements were consistent with, and polynomially related to Py, Kawakita (1/b), and Adams parameter (tau0'). CONCLUSIONS: Values of Py, 1/b, and tau0' obtained from Heckel, Kawakita, and Adams equations, respectively, can be interpreted as a measure of single particle nominal fracture strength during confined compression loading. Walker and Adams parameters were less affected, than Heckel and Kawakita parameters, by the applied pressure.

Acetaminophen↗

PubMed2001

Pyrene bioaccumulation, effects of pyrene exposure on particle-size selection, and fecal pyrene content in the oligochaete Limnodrilus hoffmeisteri (Tubificidae, Oligochaeta).

The oligochaete Limnodrilus hoffmeisteri Cleparéde was exposed to sediment-amended pyrene (0-1,196 nmol/g dry wt) for 2, 5, and 10 d to investigate sediment particle-size preference, tissue pyrene bioaccumulation (using biota-sediment accumulation factor, BSAF), fecal pyrene concentrations (using fecal-sediment accumulation factor, FSAF), and pyrene biotransformation. In non-pyrene-amended sediment, L. hoffmeisteri preferentially ingested finer sediment particles (< 3.5 microns). However, pyrene concentrations > 199 nmol/g dry weight resulted in a decreased preference for finer particles, presumably reducing pyrene exposure. Particle selectivity also changed with time such that after 10 d, worms showed an increased preference for finer particles. At high pyrene exposure, tissue pyrene concentrations rapidly attained equilibrium (maximum body residue 4.4 mumol/g wet wt, close to values cited for hydrocarbon critical body residues). Levels of biotransformation were low (mean 14%) and independent of time or pyrene concentration. Biota-sediment accumulation factor showed a negative relationship with sediment pyrene concentration; this trend may be due to reduced availability at high sediment pyrene concentrations or due to reductions in both ingestion rate and selectivity for fine, pyrene-rich particles. Fecal pyrene concentrations were depleted compared to sediment levels, suggesting removal of pyrene during gut passage by absorption. Fecal-sediment accumulation factor showed a negative relationship with increasing sediment pyrene levels.

Algorithms↗

PubMed1991

Measurement of particle size characteristics of metered dose inhaler (MDI) aerosols.

Measurement of the aerodynamic size of an aerosol allows a prediction of its deposition efficiency and behaviour in the lung. The dynamics of volatile or pressurized (MDI) aerosols presents problems not encountered in the characterization of solid or liquid particles alone. For example, the data obtained in real-time sampling as opposed to measuring an aged aerosol provide a truer representation of circumstances during actual clinical use, yet this may be difficult to achieve due to propellent evaporation. A number of particle sizing systems have been developed based upon light scattering techniques and aerodynamic principles. Each method has its limitations; in general, they successfully measure the aerodynamic size distributions of MDI aerosols. Cascade impactors, the "gold standard" of the industry have the advantage that they allow analysis of drug mass as well as other tracers within the aerosol, but the process as a whole is labour intensive, with limited resolution. Highly automated laser-based systems developed over the past 10 years measure the surface characteristics of the aerosol rather than the direct measurement of mass. Because of different values obtained from various sizing systems, it is suggested that all MDI drugs be sized using cascade impactors but that parallel data be obtained using an alternative sizing system.

Administration, Inhalation↗

PubMed2004

Relationship between pressure fluctuations and generation of organic pollutants with different particle size distributions in a fluidized bed incinerator.

The hydrodynamic behaviors of fluidization perhaps significantly influence the uniformity of fluidization in fluidized bed incinerator. Good uniformity of fluidization expressed the air across uniformly through the bed and the particles being distributed well in the fluid stream. The aggregates, flocs and channels of particles do not happen during fluidization. The Good uniformity will maintain high heat and mass distribution to improve reaction efficiency. These parameters include the height of static bed, gas velocity, mixing and distribution of bed particle, which have rarely been studied in previous investigations. Consequently, this study examines how the hydrodynamic parameters affect the generation of organic pollutants (BTEXs and PAHs) during incineration. The statistical and power spectral analysis of the measured pressure fluctuation during incineration are used to elucidate the relationship between behaviors of fluidization and generation of pollutants during incineration. Experimental results show the organic concentration does not increase with uniformity of fluidization decreasing. The reason may be the explosion of the gas and the consequent thermal shock destroy the coalescent bubbles to form small bubbles again and enhance the efficiency of transfer of oxygen to increase combustion efficiency. Additionally, the mean amplitude and fluidized index of pressure fluctuation similarly vary with the concentration of organic pollutants. These two indices can be used to assess the efficiency of combustion. The four particle size distributions could be divided into two groups by statistical analysis. The Gaussian and narrow distributions belong to one group and the binary and flat the other. The organic concentration of the Gaussian and narrow distributions are lower than that of the other distributions. Consequently, the bed materials should maintain narrow or Gaussian distributions to maintain a good combustion efficiency during incineration.

Benzene Derivatives↗

PubMed2003

Effect of particle size and interparticle force on the fluidization behavior of gas-fluidized beds.

Gas-fluidized powders of fine particles display a fluidlike regime in which the bed does not have a yield strength, it expands uniformly as the gas velocity is increased and macroscopic bubbles are absent. In this paper we test the extension of this fluidlike regime as a function of particle size and interparticle attractive force. Our results show that for sufficiently large particles, bubbling initiates just after the solidlike fluidized regime as it is obtained experimentally by other workers. A scaling behavior of the solid-phase pressure in the fluidlike regime and a predictive criterion for the onset of macroscopic bubbling are analyzed in the light of these results.

Journal Article↗

PubMed2002

Influence of the layer charge and clay particle size on the interactions between the cationic dye methylene blue and clays in an aqueous suspension.

The spectroscopic behavior of the dye MB in suspensions of different clays have been used for evaluating layer charge density influence on the adsorption properties of the particles. The clays with higher charge density, like SAz-1 and SCa-3, promote a higher aggregation and do not show deaggregation at longer times, so that practically only the aggregate peak at approximately 570 nm is observed, without any change with time. This is due to, on one side, the larger particle size that decreases the surface area available for adsorption. Additionally, the clay layers will be held together more tightly, avoiding the migration of the dye to the interlamellar region. On the other hand, SWy-1, having a lower charge density, shows a completely different behavior. The dye molecules, initially adsorbed as aggregates on the outer surface of the clay, deaggregate to form monomers that migrate to the interlamellar spaces, giving rise to absorption bands at 670 and 760 nm. Experiments using Ca-exchanged SWy-1, variation of the ionic strength by addition of salt, and the use of different size fractions of the clays confirm the finding that the main factor ruling the adsorption behavior of the probe is the size of the clay particles.

Journal Article↗

PubMed2006

Particle size distributions of oil mists in workplace atmospheres and their exposure concentrations to workers in a fastener manufacturing industry.

This study was set out to characterize size distributions of oil mists in three workplace atmospheres of the forming, threading, and heat treatment in a fastener manufacturing industry and to assess their exposures to workers. Particle size segregating samplings were conducted on the workplace atmospheres of the three selected industrial processes by using the modified Marple 8-stage cascade impactor (m-Marple). We found that mass median aerodynamic diameter (MMAD) of the fine mode and coarse mode fell to the range 0.309-0.501 microm and 8.16-13.0 microm, respectively. The fractions of inhaled particles exposed to different regions of the respiratory tracts found that the alveolar region was consistently higher than both head and tracheobronchial regions in all three studied exposure groups. Personal inhalable oil mist samplings were conducted on workers in the three selected processes revealed their exposure levels as: threading workers (2.11 mg/m3)>forming workers (1.58 mg/m3)>heat treatment workers (0.0801 mg/m3). The estimated respirable exposure concentrations for both forming and threading workers (1.34 mg/m3 and 1.40 mg/m3, respectively) were higher than the level known for "increased risk of pulmonary injury" (0.20 mg/m3) suggesting that appropriate control measures should be taken to reduce their exposures to the oil mists of the respirable fraction immediately.

Aerosols↗

PubMed2006

Tracking particle size distributions in a moving bed biofilm membrane reactor for treatment of municipal wastewater.

A study has been conducted to investigate the effect of loading rates on membrane fouling in a moving bed biofilm membrane reactor process for municipal wastewater treatment, especially analysing the fate of submicron colloidal particles and their influence on membrane fouling. Two operating conditions defined as low and high organic loading rates were tested where the development and fate of the particulate material was characterised analysing the particle size distributions throughout the process. Analysis of the membrane performance showed higher fouling rates for the high-rate conditions. The fraction of colloidal submicron particles was higher in the membrane reactor indicating that fouling by these particles was a dominant contribution to membrane fouling.

Biofilms↗

PubMed1997

Stearic acid modifies very low density lipoprotein lipid composition and particle size differently from shorter-chain saturated fatty acids in cultured rat hepatocytes.

Stearic acid as compared to myristate, palmitate, or oleate is poorly incorporated into triacylglycerol, a major lipid component of very low density lipoprotein (VLDL). The present study investigated the effects of these fatty acids on VLDL metabolism in cultured rat hepatocytes. All fatty acids stimulated [2-3H] glycerol incorporation into VLDL lipids and secretion of [3H]-labeled VLDL by hepatocytes. However, the rate of [3H]-labeled VLDL secretion in the presence of nonlabeled stearate (12.8 +/- 0.7 pmol/mg protein/4 h) was 46, 59, and 22% of that observed for those treated with myristate, palmitate, and oleate, respectively. [1-14C]Stearate as a substrate was also less effective than other labeled fatty acids to be incorporated into VLDL lipids. Of total VLDL lipids synthesized from [1-14C] stearate, triacylglycerol accounted for 78% as compared to 88-97% of that derived from palmitate, myristate, and oleate. The amounts of apoB100 and apoB48 were the same in hepatocytes treated with or without exogenous fatty acids. Similarly, the rate of apoB synthesis from [35S] methionine was not affected by exogenous fatty acids. The treatment of cells with various saturated fatty acids increased the particle size of VLDL to different extents. The largest particles of VLDL, with a mean diameter of 79.3 +/- 11.9 nm, were seen in the cells treated with stearate, followed by those treated with palmitate and myristate (45.5 +/- 9.8 and 38.6 +/- 6.8 nm, diameter, respectively). Clearly, hepatocytes treated with stearate secrete less VLDL and produce larger VLDL particles than those treated with shorter-chain saturated fatty acids.

Animals↗

PubMed2001

Particle size analysis as a tool for performance measurements in high rate effluent filtration.

In the Netherlands almost all wastewater treatment plants have been redesigned and adapted in order to remove nitrogen, phosphorus and suspended solids to a very low level. The improved effluent quality leads to a growing interest in the reuse of effluent of the modernised wastewater treatment plants. This again results in investigations on filtration techniques as deep bed filtration and membrane filtration. At the wastewater treatment plant Ede research was done on deep bed filtration in order to develop relations between particle removal and filter performance and to explore ways of optimization. The results of the experiments are rather typical for effluent of modern Dutch wastewater treatment plants. The very low concentrations of suspended solids and precipitable substances result in poor flocculating properties. From turbidity measurements it may be concluded that the best results were obtained with a dosage of flocculant. However, the particle size measurements indicated the opposite. Suspended solids calculations, based on the particle volume distributions, showed a better removal without a dosage of flocculant. From this it is concluded that a dosage of coagulant (Fe3+ or Al3+) has an adverse effect on the removal efficiencies even at low dosages (1 mg/l).

Conservation of Natural Resources↗

PubMed2005

Usefulness of low-density lipoprotein particle size measurement in cardiovascular disease prevention.

BACKGROUND: Cardiovascular disease is largely explained by the traditional risk factors, but there are several novel risk factors that have been shown to predict cardiovascular morbidity. The measurement of low-density lipoprotein particle size (LDLPS) is a novel cardiovascular risk factor, yet it is unknown whether this measurement provides additional information that may influence the subsequent medical treatment of patients. HYPOTHESIS: The measurement of LDLPS provides additional information that may influence preventive treatment for cardiovascular disease. METHODS: In an observational study of 82 patients referred to a tertiary care preventive cardiology clinic, LDLPS was dichotomized as either small or large and was determined by either the NMR LipoProfile test, the Vertical Auto Profile (VAP) cholesterol test, or gradient gel electrophoresis. Lipid profiles were obtained and Framingham risk scores were calculated. Patients were stratified by Adult Treatment Panel guidelines as being at low, intermediate, or high risk. RESULTS: The study included 56 men and 26 women with a mean age of 54 +/- 11 years. In the entire cohort of 82 patients, only 31 (38%) were at non-high-density lipoprotein (HDL) goal, only 21 (26%) were at goals for both non-HDL and HDL, and only 18 (22%) were at goal for non-HDL, HDL, and triglycerides. When considering each of the risk factor strata, 19 of 43 (44%) low-risk patients were at non-HDL goal and 12 of these also had a small LDLPS. Only 8 of 18 (44%) intermediate-risk patients were at non-HDL goal and 7 of these (88%) had small LDLPS. Finally, only four high-risk patients were at non-HDL goal and three of these (75%) had small LDLPS. CONCLUSIONS: Knowing the LDLPS could alter subsequent therapeutic recommendations for most patients who have reached target lipid values.

Adult↗

PubMed1976

The granulation of binary mixtures: the effects of the composition of the granulating solution and the initial particle size of one component on granule properties.

The effect of total solvent volume and the presence of dissolved material (other than binder) in the granulating solution, on the properties of granules prepared from lactose: boric acid mixtures has been studied. The total volume of binder solution available to powder mixtures during massing determines the ultimate average size of granules produced. Part-dissolution of powders being granulated contributes significantly to the average granule size by increasing the total solution volume and reducing the amount of powder to be wetted. Although the amount of PVP (binder) dissolved in the granulating solution contributed very little to granule size at the concentration examined, the combined effect of total volume of solution and amount of PVP present in the granulating solution determines granule strength and porosity. The effect of the initial particle size of lactose in a binary mixture with boric acid differs from its effect reported for single component systems.

Boric Acids↗

PubMed1989

Particle size of airborne mouse crude and defined allergens.

Laboratory animal allergy is a serious occupational diseases of many workers and scientists engaged in animal experimentation. Control measures depend upon characterization of allergens including airborne particles. This study measured the particle size of crude mouse urine and pelt aeroallergens generated in mouse housing rooms and compared them with mouse serum albumin, a defined major allergen. Allergens were detected by specific immunological methods. Most crude and defined allergens (74.5-86.4%) concentrated on a filter with a retention size greater than 7 microns. In distrubed air, allergen concentration increased 1.4 (albumin) to 5 (crude) fold and the proportion of small particles increased from 1.4% in calm air to 4.5% in distrubed air. This information on the generation and size distribution of aeroallergens will be important in the development of effective counter measures.

Air↗

PubMed1992

Evaluation of the Poisson distribution for estimating the quality of drug/diluent random powder mixtures. I. High particle size of the drug constituent.

Use of the Poisson distribution to estimate the quality of random mixtures was evaluated as a measure of the highest attainable degree of dose uniformity of tablets. Ingredient A was assumed to have a large particle size as compared to diluent B. In contrast to the more precise binomial distribution, for the simple Poisson approach no experiments are necessary to investigate the mean proportions of the apparent volume, av and bv, which A and B assume within the powder samples in the die. The range of volume ratios was defined where the Poisson distribution is valid. Accepting an error of 5% of the random content variation of A per sample, av may amount to up to 0.1 (10%). In terms of the proportion by mass of A, a, this range is wider, and commonly of the order of 0.2 or higher. This approach was tested with tablets prepared from mixtures of coarse sucrose A and a fine Avicel/talc diluent B at A:B (m:m) ratios from 10:90 to 50:50. Even with the 30:70 tablets, the variations of the sucrose content were still in good agreement with the content variations of the random mixtures as estimated from the Poisson distribution. Estimates of the 50:50 ratio, however, deviated from the Poisson distribution.

Algorithms↗

PubMed1998

Continuous particle size distribution analysis with dynamic light scattering. MAXAMPER: a regularization method using the maximum amplitude for the average error and the Lagrange's multipliers method.

This work deals with a new method to evaluate the scattered light intensity distributions with particle size by means of photon correlation spectroscopy. Basically, the data analysis consists in: 1) To find the least squares solution (L2 norm), and 2) To find the solution that is not significantly different from the least squares solution (within a certain significance level) that simultaneously minimizes the sum of the modulus of the residuals (L1 norm). A simple procedure is achieved by using the Lagrange's multipliers method. The two aspects that debilitate CONTIN (a rather empirical regularization based on the continuity of the distributions and the non-suitable use of the Fisher's F test) are prevented in this work, granting more meaningful results. The method was applied to simulated curves, in several typical situations (mono-modal and bi-modal, narrow and broad distributions). The quality of the results is better for narrower mono-modal distributions and bi-modal distributions having well separated peaks, as expected. Latex beads (nanospheres) having 114 nm in diameter were used to test the method in experimental conditions. MAXAMPER better reproduces monodispersed distribution profiles than CONTIN and the first moments of the distributions are in agreement with the expected value in most of the analysis.

Algorithms↗