Dispersion Particle Size Distribution Research Articles

Uncovering the impact of sea mud-containing diet on fecal fragmentation and its potential environmental risks in recirculating aquaculture system of Apostichopus japonicus

A deep understanding of fecal characteristics and fragmentation mechanism is crucial for effectively removing the solid particles in recirculating aquaculture system (RAS) of Apostichopus japonicus, however, the underlying mechanism was still unclear. This study investigated the effects of diet with different sea mud addition on the fecal characteristics and microbiota. The experimental diet were the mixture of commercial feed and sea mud at the ratio of 1:1, 1:2, 1:3, 1:4 and 1:5, in which the added amount of sea mud was 50 %, 66.67 %, 75 %, 80 % and 83.33 %, respectively. The results showed that, at the end of aquaculture, Dx(50) in group 1:3 was the highest, while group 1:5 was the lowest. The fecal particle size distribution (PSD) appeared multi peak with the increase of sea mud addition. At the end of aquaculture, group 1:3 possessed the highest microbial diversity. BugBase phenotype prediction found that the microbial phenotypes in group 1:4 were mainly involved in functional expression, such as stress tolerance and potential pathogenicity. Significant correlation between environmental factors and fecal microbiota were found. Correlation analysis between fecal particle size and fecal microbiota showed that the abundance of pathogenic bacteria such as Vibrio, was higher on fecal particles with dispersed PSD. And NH4+-N removal rate decreased when Dx(10) decreased and Dx(90) increased. Thus, it was recommended that sea mud addition in diet should be <75 % in A. japonicus RAS.

Combinatorial approach to fabricate silica doped polyvinyl alcohol/hydroxyapatite/carrageenan nanocomposite for bone regeneration applications

AbstractBone tissue engineering is a dominating approach for the fabrication of nanocomposite bone implants with superior biocompatibility and low toxicity to the surrounding tissues. Here, in this report ternary nanocomposites integrating nanohydroxyapatite/κ‐carrageenan/silica doped polyvinyl alcohol in three different ratios, that is, 60/30/10 (HCP1), 60/20/20 (HCP2), and 60/10/30 (HCP3) was constructed and a binary system comprised of nanohydroxyapatite and κ‐carrageenan was also prepared for analyzing and comparing their bone regeneration potential. The samples were characterized by various physico‐chemical techniques such as infra‐red spectroscopy, which furnished details about structural functionalities and complex formation. Rough surface morphology and dispersed particle size distribution of developed nanocomposites were revealed by scanning electron microscopy and electron transmission microscopy, respectively. Thermogravimetric analysis and differential temperature analysis revealed higher thermal stability of HCP3 nanocomposite with total weight loss of 10% and X‐ray diffraction analysis revealed average crystallite size of 15 nm for HCP3 nanocomposite. Bioactivity and biocompatibility of fabricated nanocomposites were deduced with the help of biological techniques. HCP3 manifested cell viability above 100% at 2 μg/mL concentration and exhibited hemolysis below 3% at all tested concentration favoring cell growth with minimum cytotoxicity. HCP3 also exhibited efficient apatite layer deposition, optimum swelling ability and improved biodegradability (~30%) and anti‐bacterial activity predicting it as a promising nanocomposite implant for future orthopedic applications.

Droplet-induced optical effects in an opto-microfluidic cross-configuration system

A comprehensive description of all the optical phenomena occurring when light interacts with a moving dispersed phase in a constrained environment such as a real microfluidic channel is needed to perform a quantitative analysis as well as predictive one. This requires identifying fingerprints in the detected optical signal that are doubtlessly correlated with the shape and content type of the dispersed phase from those connected to uncertainties of the optical detection systems and/or instabilities in the microfluidics apparatus leading to dispersed phase size distribution. This article aims to model all the droplet-induced optical effects in an opto-microfluidic cross-configuration system and quantify how diffraction, transmission, absorbance, and reflection contribute to the overall response in the detected intensity after light-matter interaction. The model has been tested in the case of water droplets dispersed in hexadecane continuous phase as generated in an opto-microfluidic platform where optical waveguides are fully integrated with the microfluidic channels, so that light illuminates the flowing droplets from the channel wall and collected on the opposite side. A critical discussion of the impact of geometry and constrains is proposed as well as the impact of each contribute in terms of fingerprints in the detected signal. The good agreement obtained demonstrates the potentialities of both the derived model and the cross-configuration, getting information on droplet characteristics from the intensity arising from its light interaction.

Particulate systems from maqui (Aristotelia chilensis) wastes to be used as nutraceutics or high value-added ingredients

Powdered ingredients from maqui wastes were produced and the effect of drying method (air- and freeze-drying) and particle size on physicochemical and bioactive properties was investigated. Among the particulate systems of smaller particle size that showed the most balanced insoluble to soluble fiber ratio and the best hydration and oil absorption properties, the freeze-dried ones presented the best retention of polyphenols, anthocyanins, and antioxidant capacity. These powders could be used as ingredients in premixes for the development of foods for diabetes or gluten-free diets. The powders of higher granulometry presented excellent flowability and more dispersed particle size distribution, being more adequate for the development of composite foods or nutraceutics.

Highly stable and efficient electrorheological suspensions with hydrophobic interaction

HypothesisElectrorheological fluid (ERF) is a kind of suspension or colloid composed of fine particles and insulating oil as continuous phase. The second miscible liquid phase with less affinity to the particles than the continuous phase is expected to influence particles aggregation, assembly and spanning mesostructures. Hence, it should be possible to tune the rheological and electrorheological properties and stability by the addition of second miscible liquid with different chain length and substituents. ExperimentsWe developed a giant ERF (GERF) with a binary liquid phase (BLP) by the addition of alkane to the silicone oil continuous phase. We studied the shear stress and viscosity under different shear rates, thixotropy and particle size distributions of these suspensions and characterized the concentration variation of GERFs under quiescent conditions by measuring the backscattering light intensity variation through vertical scanning. FindingsThe dispersed particle size distribution is broadened, which produces higher static yield stress and lower zero-field viscosity than those of a single-liquid-phase GERF. The ER efficiency is much higher with the addition of alkane, reaching 10656, which is 1.8 times larger than that of single-liquid-phase suspensions. We performed 100-day stability testing and found that the GERF with 1-phenyldodecane showed excellent stability and performance.

A population balance model for large eddy simulation of polydisperse droplet evolution

In the context of many applications of turbulent multi-phase flows, knowledge of the dispersed phase size distribution and its evolution is critical to predicting important macroscopic features. We develop a large eddy simulation (LES) model that can predict the turbulent transport and evolution of size distributions, for a specific subset of applications in which the dispersed phase can be assumed to consist of spherical droplets, and occurring at low volume fraction. We use a population dynamics model for polydisperse droplet distributions specifically adapted to a LES framework including a model for droplet breakup due to turbulence, neglecting coalescence consistent with the assumed small dispersed phase volume fractions. We model the number density fields using an Eulerian approach for each bin of the discretized droplet size distribution. Following earlier methods used in the Reynolds-averaged Navier–Stokes framework, the droplet breakup due to turbulent fluctuations is modelled by treating droplet–eddy collisions as in kinetic theory of gases. Existing models assume the scale of droplet–eddy collision to be in the inertial range of turbulence. In order to also model smaller droplets comparable to or smaller than the Kolmogorov scale we extend the breakup kernels using a structure function model that smoothly transitions from the inertial to the viscous range. The model includes a dimensionless coefficient that is fitted by comparing predictions in a one-dimensional version of the model with a laboratory experiment of oil droplet breakup below breaking waves. After initial comparisons of the one-dimensional model to measurements of oil droplets in an axisymmetric jet, it is then applied in a three-dimensional LES of a jet in cross-flow with large oil droplets of a single size being released at the source of the jet. We model the concentration fields using $N_{d}=15$ bins of discrete droplet sizes and solve scalar transport equations for each bin. The resulting droplet size distributions are compared with published experimental data, and good agreement for the relative size distribution is obtained. The LES results also enable us to quantify size distribution variability. We find that the probability distribution functions of key quantities such as the total surface area and the Sauter mean diameter of oil droplets are highly variable, some displaying strong non-Gaussian intermittent behaviour.

Sparkling nights and very hot days on WASP-18b: the formation of clouds and the emergence of an ionosphere

Context. WASP-18b is an ultra-hot Jupiter with a temperature difference of up to 2500 K between day and night. Such giant planets begin to emerge as a planetary laboratory for understanding cloud formation and gas chemistry in well-tested parameter regimes in order to better understand planetary mass loss and for linking observed element ratios to planet formation and evolution. Aims. We aim to understand where clouds form, their interaction with the gas-phase chemistry through depletion and enrichment, the ionisation of the atmospheric gas, and the possible emergence of an ionosphere on ultra-hot Jupiters. Methods. We used 1D profiles from a 3D atmosphere simulation for WASP-18b as input for kinetic cloud formation and gas-phase chemical equilibrium calculations. We solved our kinetic cloud formation model for these 1D profiles, which sample the atmosphere of WASP-18b at 16 different locations along the equator and in the mid-latitudes. We derived the gas-phase composition consistently. Results. The dayside of WASP-18b emerges as completely cloud-free as a result of the very high atmospheric temperatures. In contrast, the nightside is covered in geometrically extended and chemically heterogeneous clouds with dispersed particle size distributions. The atmospheric C/O ratio increases to &gt;0.7 and the enrichment of the atmospheric gas with cloud particles is ρd/ρgas &gt; 10−3. The clouds that form at the limbs appear located farther inside the atmosphere, and they are the least extended. Not all day- to nightside terminator regions form clouds. The gas phase is dominated by H2, CO, SiO, H2O, H2S, CH4, and SiS. In addition, the dayside has a substantial degree of ionisation that is due to ions such as Na+, K+, Ca+, and Fe+. Al+ and Ti+ are the most abundant of their element classes. We find that WASP-18b, as one example for ultra-hot Jupiters, develops an ionosphere on the dayside.

Development of aqueous dispersions of Coenzyme Q10 for pulmonary delivery and the dynamics of active vibrating-mesh aerosolization

Coenzyme Q10 (CoQ10) is a poorly-water soluble compound that is being investigated for the treatment of carcinomas. The aim of this study was to investigate the feasibility of preparing phospholipid-stabilized dispersions of the anticancer agent for continuous pulmonary delivery using a vibrating-mesh nebulizer. We determined the physicochemical properties (drug particle size distribution in dispersion, zeta potential, surface tension, and rheology) and compared the aerosolization profiles (nebulization performance, aerodynamic drug deposition and total emitted dose) of dispersions of CoQ10 prepared with different phospholipids. The hydrodynamic sizes of the drug particles in dispersion were primarily in the submicron range, but formulations with drug particle sizes greater than the aperture size of the nebulizer presented superior aerosolization profiles. At high shear rates, certain formulations presented increased shear-thickening behavior, which was connected to a decrease in mass and drug output over time, and with decreased aerodynamic and geometric sizes. Other formulations presented shear-thinning behavior and showed similarly high drug depositions. In this investigation, we found that dispersed formulations of CoQ10 presented different in vitro performance for pulmonary delivery based on their rheological behavior. In conclusion, this characterization methodology provides an innovative approach to screen formulations of poorly-water soluble compounds for continuous (no clogging) active vibrating-mesh nebulization.

Population Balance Modeling of Breakage and Coalescence of Dispersed Bubbles or Droplets in Multiphase Systems

Modeling of breakage and coalescence of dispersed phases such as bubbles or droplets in multiphase systems is of paramount importance to the control of the dispersed phase size distribution in process industry. Population balance model (PBM) has become a rountine tool to simulate the breakage, coalescence and size distribuiton of dispersed phase. However, the current kernel functions for breakage and coalescence in PBM are either derived from statistical models or based on some phenomenological models, empirical correlations or semi theoretical methods, since the physics of breakage and coalescence in multi-phase systems is complex. As a result, few models could completely considers all of the physical constraints relevant to the complex flow field and material properties, and it is still a challenging issue to accurately predict the breakage and coalescence for different operating conditions. This article gives a systematic overview of the mechanisms and models about the breakage and coalescence of bubbles or droplets, and the numerical algothirm for population balance equations as well as the application of PBM simulation in gas-liquid or liquid-liquid systems. Finally, the state-of-the-art and future development of PBM are analyzed.

Rapid sphere sizing using a Bayesian analysis of reciprocal space imaging data

Dispersed systems are important in many applications in a wide range of industries such as the petroleum, pharmaceutical and food industries. Therefore the ability to control and non-invasively measure the physical properties of these systems, such as the dispersed phase size distribution, is of significant interest, in particular for concentrated systems, where microscopy or scattering techniques may not apply or with very limited output quality. In this paper we show how reciprocal space data acquired using both 1D magnetic resonance imaging (MRI) and 2D X-ray micro-tomographic (X-ray μCT) data can be analysed, using a Bayesian statistical model, to extract the sphere size distribution (SSD) from model sphere systems and dispersed food foam samples. Glass spheres-in-xanthan gels were used as model samples with sphere diameters (D) in the range of 45μm⩽D⩽850μm. The results show that the SSD was successfully estimated from both the NMR and X-ray μCT with a good degree of accuracy for the entire range of glass spheres in times as short as two seconds. After validating the technique using model samples, the Bayesian sphere sizing method was successfully applied to air/water foam samples generated using a microfluidics apparatus with 160μm⩽D⩽400μm. The effect of different experimental parameters such as the standard deviation of the bubble size distribution and the volume fraction of the dispersed phase is discussed.

Effects of process method and quiescent coarsening on dispersed-phase size distribution in polymer blends: comparison of solid-state shear pulverization with intensive batch melt mixing

We compare how solid-state shear pulverization (SSSP), batch melt mixing (BMM), and static melt-state annealing affect the morphology of an immiscible blend of polypropylene (PP) and ethylene-α-olefin copolymer (EOC). For 85/15 wt% PP/EOC blends, SSSP and BMM led to log-normal distributions of dispersed-phase particle size. The SSSP blend had smaller average particle diameters (e.g., D n = 0.24 μm) and a narrower particle size distribution (e.g., D w/D n = 1.17; D v/D n = 1.56) than the BMM blend (D n = 0.28 μm; D w/D n = 1.25; D v/D n = 1.79). The fact that BMM is subject to thermodynamically and flow-induced coalescence while SSSP is not, can lead to smaller particle sizes and a narrower distribution by SSSP. Although annealing at 200 °C for 30 and 90 min led to continuous growth of average particle size in the BMM blend, the particle-size dispersity remained virtually unchanged. In contrast, after 30-min annealing at 200 °C, the SSSP blend showed less growth in $$D_{{_{n} }}^{{^{3} }}$$ than the BMM blend but a dramatic increase in particle-size dispersity and a loss of the log-normal size distribution. Between 30 and 90 min, there was at most slight growth in $$D_{{_{n} }}^{{^{3} }}$$ , consistent with partial compatibilization caused by in situ block copolymer formation during SSSP, and major reductions in D w/D n and D v/D n close to those of the BMM blend and recovery of the log-normal size distribution. These results suggest that caution should be used in correlating immiscible blend properties to a particular average particle size as that value may not reflect possible complexity of the underlying size distribution.

Water Modeling Study on Dispersed Phase Size Distribution and Interface Areas in Metallurgical Multiphase Reactor

The combined blowing process of metallurgical multiphase reactor was simulated by water modeling. The effects of operation conditions on dispersed phase size distribution were studied and an empirical formula was obtained. Based on the law of additive codimensions, the interface areas under different operation conditions were calculated by means of box counting and projection relationship. The results show that the frequency of dispersed phase with certain granularity level are in a certain proportion to its size level, and the dispersed phase areas are influenced by the top and bottom combined blowing.

Evolution of droplets in subsea oil and gas blowouts: Development and validation of the numerical model VDROP-J

The droplet size distribution of dispersed phase (oil and/or gas) in submerged buoyant jets was addressed in this work using a numerical model, VDROP-J. A brief literature review on jets and plumes allows the development of average equations for the change of jet velocity, dilution, and mixing energy as function of distance from the orifice. The model VDROP-J was then calibrated to jets emanating from orifices ranging in diameter, D, from 0.5mm to 0.12m, and in cross-section average jet velocity at the orifice ranging from 1.5m/s to 27m/s. The d50/D obtained from the model (where d50 is the volume median diameter of droplets) correlated very well with data, with an R2=0.99. Finally, the VDROP-J model was used to predict the droplet size distribution from Deepwater Horizon blowouts. The droplet size distribution from the blowout is of great importance to the fate and transport of the spilled oil in marine environment.

Removal of Total Organic Carbon from Sewage Wastewater Using Poly(ethylenimine)-Functionalized Magnetic Nanoparticles

The increased levels of organic carbon in sewage wastewater during recent years impose a great challenge to the existing wastewater treatment process (WWTP). Technological innovations are therefore sought that can reduce the release of organic carbon into lakes and seas. In the present study, magnetic nanoparticles (NPs) were synthesized, functionalized with poly(ethylenimine) (PEI), and characterized using TEM (transmission electron microscopy), X-ray diffraction (XRD), FTIR (Fourier transform infrared spectroscopy), CCS (confocal correlation spectroscopy), SICS (scattering interference correlation spectroscopy), magnetism studies, and thermogravimetric analysis (TGA). The removal of total organic carbon (TOC) and other contaminants using PEI-coated magnetic nanoparticles (PEI-NPs) was tested in wastewater obtained from the Hammarby Sjöstadsverk sewage plant, Sweden. The synthesized NPs were about 12 nm in diameter and showed a homogeneous particle size distribution in dispersion by TEM and CCS analyses, respectively. The magnetization curve reveals superparamagnetic behavior, and the NPs do not reach saturation because of surface anisotropy effects. A 50% reduction in TOC was obtained in 60 min when using 20 mg/L PEI-NPs in 0.5 L of wastewater. Along with TOC, other contaminants such as turbidity (89%), color (86%), total nitrogen (24%), and microbial content (90%) were also removed without significant changes in the mineral ion composition of wastewater. We conclude that the application of PEI-NPs has the potential to reduce the processing time, complexity, sludge production, and use of additional chemicals in the WWTP.

The coordinated relationship between vortex finder parameters and performance of hydrocyclones for separating light dispersed phase

Hydrocyclones for separating light dispersed phase are applicable to various processes in the separation of light dispersion. The relationship of the structure parameters and flow field is in the frontier of the research and not clear so far. In this paper, Phase Doppler Particle Analyzer (PDPA) was used for the first time to systematically study the influence of the change of structure and size of vortex finder on the zero axial velocity wave zone (ZAVWZ), the tangential velocity gradient, the centrifugal separation factor and the size distribution of dispersed phase. The hydrocyclone was designed with diameter of Φ35 mm, hollow glass beads ( d 50 = 30.61 μm, ρ = 0.82 g/cm 3) were used as the dispersed phase and water was used as the continuous phase. The test results were used as the evaluation index to optimize the depth of vortex finder at 0.143 L s and its diameter at 0.071 D. The performance of the hydrocyclone was also examined under the same material and flow condition as the PDPA test for flow field, which showed the separation performance of the optimized hydrocyclone reached up to 92.3%, while the inlet flow rate was 1.5 m 3/h and the split ratio was 8%. At last, the reliability for taking the test results, the length of zero axial velocity wave zone (ZAVWZ), the centrifugal separation factor and the tangential velocity gradient as the evaluation index were also verified.

Effect of the Size Distribution of Nanoscale Dispersed Particles on the Zener Drag Pressure

In this article, a new relationship for the calculation of the Zener drag pressure is described in which the effect of the size distribution of nanoscale dispersed particles is taken into account, in addition to particle radius and volume fraction, which have been incorporated in the existing relationships. Microstructural observations indicated a clear correlation between the size distribution of dispersed particles and recrystallized grain sizes in the AA7020 aluminum alloy. However, the existing relationship to calculate the Zener drag pressure yielded a negligible difference of 0.016 pct between the two structures homogenized at different conditions resulting in totally different size distributions of nanoscale dispersed particles and, consequently, recrystallized grain sizes. The difference in the Zener drag pressure calculated by the application of the new relationship was 5.1 pct, being in line with the experimental observations of the recrystallized grain sizes. Mathematical investigations showed that the ratio of the Zener drag pressure from the new equation to that from the existing equation is maximized when the number densities of all the particles with different sizes are equal. This finding indicates that in the two structures with identical parameters except the size distribution of nanoscale dispersed particles, the one that possesses a broader size distribution of particles, i.e., the number densities of particles with different sizes being equal, gives rise to a larger Zener drag pressure than that having a narrow size distribution of nanoscale dispersed particles, i.e., most of the particles being in the same size range.

Effects of concentration of dispersions on particle sizing during production of fine particles in wet grinding process

Stirred media milling is a prospective technology for producing colloidal dispersions by means of wet grinding process. In the past, many researchers have studied the effects of different operating parameters such as size, shape, nature and quantity of grinding medium, the speed of agitator in grinding chamber, the feed rate of dispersions, etc. in stirred media mills. However, it is still less known how particle sizing which generates valuable information of particle size of the product to interpret, control and optimize the grinding process, is influenced by the concentration of the dispersion during stirred media milling where particles change their size from micron to colloidal range rapidly. One of the reasons of this lack had been our incapability in the past to study the particle size distribution of dispersions without dilution. The recent advent of acoustic attenuation spectroscopy is known to be capable of studying dispersions without dilution, under real process conditions and on line. The study employs acoustic attenuation spectroscopy to investigate the effects of concentration of dispersions of CaCO 3 on its particle sizing during size reduction process in a stirred media mill (LabStar manufactured by NETZSCH). The dispersions of CaCO 3 at 5%, 10%, 20% and 30% (m/m) were studied about six hours under a selected set of operating conditions. Contrary to the existing knowledge obtained through other techniques of particle sizing that are based on the principle of dilution, acoustic attenuation spectroscopy shows that, under certain grinding time at given operating conditions, increase in concentration of dispersion results in better grinding results yielding smaller particles. The causes behind the differences in results of acoustic attenuation spectroscopy and dynamic light scattering have been thoroughly investigated. We find certain limitations of acoustic attenuation spectroscopy in particle sizing. A typical phenomenon which causes misleading trends in particle sizing is multiple scattering in acoustic measurements. Multiple scattering, particularly, influences acoustic results when particles approach to fine size range during size reduction process.

Effects of soil moisture and dried raindroplet crust on saltation and dust emission

Field experiments using a sand particle counter and an optical particle counter clarified the links between saltation and dust emission under wet and weakly crusted conditions in a fallow field previously cultivated with wheat in Australia. A crust was formed by the impact of raindroplets after small precipitation events. A little soil moisture enhanced the strengths of crust and aggregation even though the soil was dried. Dust concentration was proportional to friction wind velocity, but the proportionality was dependent on ground surface conditions, such as the minimally dispersed particle size distribution of parent soil and the presence or absence of crust.

OIL DROPLET SIZE DISTRIBUTION AS A FUNCTION OF ENERGY DISSIPATION RATE IN AN EXPERIMENTAL WAVE TANK

ABSTRACT The U.S. National Research Council (NRC) Committee on Understanding Oil Spill Dispersants: Efficacy and Effects (2005) identified two factors that require further investigation in chemical oil dispersant efficacy studies: 1) quantification of mixing energy at sea as energy dissipation rate and 2) dispersed particle size distribution. To fully evaluate the significance of these factors, a wave tank facility was designed and constructed to conduct controlled oil dispersion studies. A factorial experimental design was used to study the dispersant effectiveness as a function of energy dissipation rate for two oils and two dispersants under three different wave conditions, namely regular non-breaking waves, spilling breakers, and plunging breakers. The oils tested were weathered MESA and fresh ANS crude. The dispersants tested were Corexit 9500 and SPC 1000 plus water for no-dispersant control. The wave tank surface energy dissipatation rates of the three waves were determined to be 0.005, 0.1, and 1 m2/s3, respectively. The dispersed oil concentrations and droplet size distribution, measured by in-situ laser diffraction, were compared to quantify the chemical dispersant effectiveness as a function of energy dissipation rate. The results indicate that high energy dissipation rate of breaking waves enhanced chemical dispersant effectiveness by significantly increasing dispersed oil concentration and reducing droplet sizes in the water column (p &amp;lt;0.05). The presence of dispersants and breaking waves stimulated the oil dispersion kinetics. The findings of this research are expected to provide guidance to disperant application on oil spill responses.

Particle size distribution by space or time dependent extinction profiles obtained by analytical centrifugation (concentrated systems)

The particle size distributions of dispersions of fine particles were determined by an analytical photocentrifuge, which allows to measure space and time resolved extinction profiles (STEP™-Technology) during the centrifugation of up to 12 samples simultaneously. This type of centrifuge provides a powerful tool for the characterisation and quality control of dispersions. While the variation of the light extinction curves caused by centrifugal segregation allows a qualitative description, a rigorous formulation can give access to detailed quantitative characterisation. The particle size distribution may be derived by two procedures: analysing the variation of the extinction at any point of the sample over centrifugation time or analysing the extinction variation over the entire sample length at any time of the centrifugation. The advantage of the second analytical procedure is its potential to save time. Measurements of dispersions, with monomodal, multimodal and broad particle size distributions in the nanometer and micrometer range show a good agreement between both analytical procedures. Also, analytical centrifugation has a great potential to measure dispersions without dilution. Therefore in addition two effects will be discussed, hindered settling and multiple scattering. Experimental results from concentrated suspensions and emulsions show the applicability of this new measurement principle. Results will be compared with those of other measurement techniques (SEM, PCS, Laser diffraction).