High-Resolution Latex State 13C-NMR Spectroscopy: Part II. Effect of Particle Size and Temperature

2001 ◽  
Vol 74 (2) ◽  
pp. 295-302 ◽  
Author(s):  
Seiichi Kawahara ◽  
Yoshinobu Isono ◽  
Keiko Washino ◽  
Toshiko Morita ◽  
Yasuyuki Tanaka
Keyword(s):  
Particle Size ◽  
Diffusion Coefficient ◽  
Brownian Motion ◽  
Signal To Noise Ratio ◽  
Particle Diameter ◽  
13C Nmr Spectroscopy ◽  
Colloidal Dispersion ◽  
Colloidal Dispersions ◽  
Half Width ◽  
State Measurement

Abstract Latex state C-NMR measurements were made for colloidal dispersions of polymer, using the observation conditions similar to those used in solution state measurement. The colloidal dispersion which showed broad and bimodal distributions in particle size was fractionated by centrifugation into four fractions with different volume mean particle diameter ranging from 0.121 to 1.31 µm with narrow and unimodal distributions. The signal to noise ratio, half width and intensity of each resolved carbon resonance for the fractionated dispersions were dependent upon the particle diameter. The intensity of the carbon resonances increased to 100% as the particle diameter decreased and temperature was raised. This is explained with respect to the increase in diffusion coefficient of Brownian motion of the particle. The intensity and the half width of the signals were superimposed against the diffusion coefficient of Brownian motion.

Application of Plakett-Burman Screening Design in Optimization of Process Parameters for Formulation of Canaglifozin Nanosuspension

2020 ◽  
Vol 13 (6) ◽  
pp. 5208-5216
Author(s):  
Nisha Patel ◽  
Hitesh A Patel
Keyword(s):  
Particle Size ◽  
Particle Diameter ◽  
Spherical Shape ◽  
Water Soluble ◽  
Pareto Chart ◽  
Independent Variables ◽  
Mean Particle Size ◽  
Screening Design ◽  
Stirring Time ◽  
Response Variables

In this study, we sought to improve the dissolution characteristics of a poorly water-soluble BCS class IV drug canaglifozin, by preparing nanosuspension using media milling method. A Plackett–Burman screening design was employed to screen the significant formulation and process variables. A total of 12 experiment were generated by design expert trial version 12 for screening 5 independent variables namely the amount of stabilizer in mg (X1), stirring time in hr (X2), amt of Zirconium oxide beads in gm (X3), amount of drug in mg (X4) and stirring speed in rpm (X5) while mean particle size in nm (Y1) and drug release in 10 min. were selected as the response variables. All the regression models yielded a good fit with high determination coefficient and F value. The Pareto chart depicted that all the independent variables except the amount of canaglifozin had a significant effect (p<0.001) on the response variables. The mathematical model for mean particle size generated from the regression analysis was given by mean particle size = +636.48889 -1.28267 amt of stabilizer(X1) -4.20417 stirring time (X2) -7.58333 amt of ZrO2 beads(X3) -0.105556 amt of drug(X4) -0.245167 stirring speed(X5) (R2=0.9484, F ratio=22.07, p<0.001). Prepared canaglifozin nanosuspension exemplified a significant improvement (p<0.05) in the release as compared to pure canaglifozin and marketed tablet with the optimum formulation releasing almost 80% drug within first 10min. Optimized nanosuspension showed spherical shape with surface oriented stabilizer molecules and a mean particle diameter of 120.5 nm. There was no change in crystalline nature after formulation and it was found to be chemically stable with high drug content.

Effect of Diameter and Surface Area of Carbon Black Particles on Certain Properties of Rubber Compounds

1944 ◽  
Vol 17 (2) ◽  
pp. 451-474
Author(s):  
D. Parkinson
Keyword(s):  
Particle Size ◽  
Tensile Strength ◽  
Carbon Black ◽  
Abrasion Resistance ◽  
Particle Diameter ◽  
Stiffness Modulus ◽  
Carbon Structures ◽  
Rubber Compounds ◽  
Regular Manner ◽  
Tear Resistance

Abstract Carbon blacks can be grouped into different classes according to the way in which their fineness of division relates to different properties in rubber. Within any one class the principal properties vary in a regular manner with particle size. The normal class consists of the furnace carbons, Kosmos (Dixie)-40, Statex, the rubber-grade impingement carbons, and possibly, the color-grade impingement carbons. The subnormal classes consist of thermal carbons and acetylene and lamp blacks. Irrespective of the above classification, the properties which depend more on fineness of division than on other factors are rebound resilience, abrasion resistance, tensile strength and tear resistance. The lower limit of particle diameter for best tensile strength and tear resistance appears to be higher than that for abrasion resistance. B.S.I, hardness and electrical conductivity are properties which depend at least as much on other factors as on particle size. Stiffness (modulus) depends more on other factors than on particle size. Factors modifying the effects of particle size (or specific surface) include the presence of carbon-carbon structures and a reduction in strength of bond in rubber-carbon structures. Carbon black is thought to exist in rubber in four states: agglomerated, flocculated, dispersed, and bonded to the rubber molecules (the reënforcing fraction). Abrasion resistance is regarded as providing the only reliable measure of reënforcement.

scholarly journals Preparation of Polyetherimide Nanoparticles by a Droplet Evaporation-Assisted Thermally Induced Phase-Separation Method

Polymers ◽  
2021 ◽  
Vol 13 (10) ◽  
pp. 1548
Author(s):  
Peng Zhu ◽  
Huapeng Zhang ◽  
Hongwei Lu
Keyword(s):  
Particle Size ◽  
Electron Microscope ◽  
Phase Separation ◽  
Average Particle Size ◽  
Particle Diameter ◽  
Droplet Evaporation ◽  
Average Particle ◽  
Thermally Induced Phase Separation ◽  
Thermally Induced ◽  
Pei Nanoparticles

The droplet evaporation effect on the preparation of polyetherimide (PEI) nanoparticles by thermally induced phase separation (TIPS) was studied. PEI nanoparticles were prepared in two routes. In route I, the droplet evaporation process was carried out after TIPS. In route II, the droplet evaporation and TIPS processes were carried out simultaneously. The surface tension and shape parameters of samples were measured via a drop shape analyzer. The Z-average particle diameter of PEI nanoparticles in the PEI/dimethyl sulfoxide solution (DMSO) suspension at different time points was tested by dynamic light scattering, the data from which was used to determine the TIPS time of the PEI/DMSO solution. The natural properties of the products from both routes were studied by optical microscope, scanning electron microscope and transmission electron microscope. The results show that PEI nanoparticles prepared from route II are much smaller and more uniform than that prepared from route I. Circulation flows in the droplet evaporation were indirectly proved to suppress the growth of particles. At 30 °C, PEI solid nanoparticles with 193 nm average particle size, good uniformity, good separation and good roundness were obtained. Route I is less sensitive to temperature than route II. Samples in route I were still the accumulations of micro and nanoparticles until 40 °C instead of 30 °C in route II, although the particle size distribution was not uniform. In addition, a film structure would appear instead of particles when the evaporation temperature exceeds a certain value in both routes. This work will contribute to the preparation of polymer nanoparticles with small and uniform particle size by TIPS process from preformed polymers.

STRUCTURAL PARAMETERS OF AQUEOUS COLLOIDAL DISPERSIONS OF FULLERENE C60

2019 ◽  
pp. 31-37
Author(s):  
V.Yu. Fokina ◽  
E.А. Kizima ◽  
I.V. Miheev ◽  
A.I. Ivankov ◽  
V.M. Garamus
Keyword(s):  
Particle Size ◽  
Fractal Dimension ◽  
Particle Size Distribution ◽  
Structural Parameters ◽  
Colloidal Dispersions ◽  
Fullerene C60 ◽  
Solvent Exchange ◽  
X Ray ◽  
Dense Nucleus ◽  
Exchange Technique

Two types of fullerene C60 water dispersions were investigated by a small-angle X-ray and neutron scattering. As a result, structural parameters of fullerene aggregates were obtained. The water dispersions were obtained by the solvent-exchange technique and by huge dilution of initial C60/Nmethylpyrrolidone solution. The structure organization of water dispersions is considered in respect to their technique preparation. It was shown that fullerene aggregates were characterized by highly polydispersity in size for all dispersions. In the case of son/nC60 dispersion it was found that fullerenes formed aggregates with a dense nucleus (namely a surface fractal) with a radius of 58 ± 1 nm and a fractal dimension of 2.3. In turn, the nmp/nC60 system was characterized by the branched aggregates with fractal dimension 1.5 and bimodal particle size distribution.

Gastric emptying of nondigestible solids in dogs: a hydrodynamic correlation

1990 ◽  
Vol 258 (1) ◽  
pp. G65-G72 ◽  
Author(s):  
P. J. Sirois ◽  
G. L. Amidon ◽  
J. H. Meyer ◽  
J. Doty ◽  
J. B. Dressman
Keyword(s):  
Particle Size ◽  
Gastric Emptying ◽  
Gravitational Constant ◽  
Particle Density ◽  
Particle Diameter ◽  
High Viscosity ◽  
Fluid Viscosity ◽  
Fluid Flow Rate ◽  
Hydrodynamic Correlation ◽  
Viscosity Polymer

The influence of particle size, particle density, fluid viscosity, and fluid flow rate on the gastric emptying of nondigestible solids was investigated in five dogs with chronically placed fistulas. Six hundred and fifty particles of 13 different size and density combinations were administered simultaneously with 500 ml of either normal saline or low-, medium-, or high-viscosity polymer solutions. The canine stomach was found to discriminate between these solids on the basis of size and density at all levels of viscosity above saline. The observed patterns of emptying are consistent with the hypothesis that gastric emptying of nondigestible solids is governed in part by hydrodynamics and correlate well with the gastric-emptying coefficient (GEC), a dimensionless grouping of variables that takes the form GEC = (Dpy/Dp) [g(rho f - rho p)Dp2]/[eta (nu)] where [g(rho f - rho p)] is particle buoyancy consisting of fluid (rho f) and particle (rho p) densities and g, the gravitational constant; (Dp) is the particle diameter, (Dpy) the estimated pyloric diameter, eta the fluid viscosity, and (nu) the average linear velocity of fluid exiting the stomach.

scholarly journals Digital microscopic image application (DMIA), an automatic method for particle size distribution analysis in waste activated sludge

2021 ◽  
Author(s):  
S. Cazares ◽  
J. A. Barrios ◽  
C. Maya ◽  
G. Velásquez ◽  
M. Pérez ◽  
...  
Keyword(s):  
Particle Size ◽  
Particle Size Distribution ◽  
Activated Sludge ◽  
Size Distribution ◽  
Particle Diameter ◽  
Diffraction Method ◽  
Laser Diffraction ◽  
Waste Activated Sludge ◽  
Equivalent Diameter ◽  
Distribution Analysis

Abstract An important physical property in environmental samples is particle size distribution. Several processes exist to measure particle diameter, including change in electrical resistance, blocking of light, the fractionation of field flow and laser diffraction (these being the most commonly used). However, their use requires expensive and complex equipment. Therefore, a Digital Microscopic Imaging Application (DMIA) method was developed adapting the algorithms used in the Helminth Egg Automatic Detector (HEAD) software coupled with a Neural Network (NN) and Bayesian algorithms. This allowed the determination of particle size distribution in samples of waste activated sludge (WAS), recirculated sludge (RCS), and pretreated sludge (PTS). The recirculation and electro-oxidation pre-treatment processes showed an effect in increasing the degree of solubilization (DS), decreasing particle size and breakage factor with ranges between 44.29%, and 31.89%. Together with a final NN calibration process, it was possible to compare results. For example, the 90th percentile of Equivalent Diameter (ED) value obtained by the DMIA with the corresponding result for the laser diffraction method. DMIA values: 228.76 μm (WAS), 111.18 μm (RCS), and 84.45 μm (PTS). DMIA processing has advantages in terms of reducing complexity, cost and time, and offers an alternative to the laser diffraction method.

scholarly journals Calibration of the passive cavity aerosol spectrometer probe for airborne determination of the size distribution

2013 ◽  
Vol 6 (3) ◽  
pp. 4123-4152 ◽  
Author(s):  
Y. Cai ◽  
J. R. Snider ◽  
P. Wechsler
Keyword(s):  
Particle Size ◽  
Size Distribution ◽  
Scattered Light ◽  
Particle Diameter ◽  
Polystyrene Latex ◽  
Calibration Methods ◽  
Research Aircraft ◽  
Amplifier Gain ◽  
Gain Stage

Abstract. This work describes calibration methods for the particle sizing and particle concentration systems of the passive cavity aerosol spectrometer probe (PCASP). Laboratory calibrations conducted over six years, in support of the deployment of a PCASP on a cloud physics research aircraft, are analyzed. Instead of using the many calibration sizes recommended by the PCASP manufacturer, a relationship between particle diameter and scattered light intensity is established using three sizes of mobility-selected polystyrene latex particles, one for each amplifier gain stage. In addition, studies of two factors influencing the PCASP's determination of the particle size distribution – amplifier baseline and particle shape – are conducted. It is shown that the PCASP-derived size distribution is sensitive to adjustments of the sizing system's baseline voltage, and that for aggregate spheres, a PCASP-derived particle size and a sphere-equivalent particle size agree within uncertainty dictated by the PCASP's sizing resolution. Robust determination of aerosol concentration, and size distribution, also require calibration of the PCASP's aerosol flowrate sensor. Sensor calibrations, calibration drift, and the sensor's non-linear response are documented.

scholarly journals Interactions of Human Fibrinogen in Solution

1977 ◽  
Author(s):  
E. Serrallach ◽  
W. Känzig ◽  
V. Hofmann ◽  
P.W. Straub ◽  
M. Zulauf
Keyword(s):  
Diffusion Coefficient ◽  
Brownian Motion ◽  
Rotational Diffusion ◽  
Sedimentation Coefficient ◽  
Translational Diffusion ◽  
Initial Slope ◽  
Single Pair ◽  
Human Fibrinogen ◽  
Diffusion Constants ◽  
End To End

The intriguing diversity of published translational diffusion constants for the fibrinogen molecule can hardly be explained, unless interactions between the molecules are postulated. In the present study we have investigated the possible effect of molecular association and electrostatic intermolecular interactions on the Brownian motion. The translational diffusion coefficient DT, the rotational diffusion coefficient around the minor axis DR and the sedimentation coefficient have been measured. The methods used were dynamic light scattering and analytical ultracentrifugation. The samples were solutions of purified human fibrinogen. The correlation-function corresponding to DT deviates from a single exponential. The initial slope is found to depend on concentration, being DT = (1.7 ± 0.3) 10-7 cm2/s at 10mg/ml, pH 7.4 and 0.15 molar Tris-NaCl, and increases at fibrinogen concentrations below 2mg/ml. These results are compatible with a polydispers solution, in which single molecules are in equilibrium with pair and higher aggregates. The nature of the aggregates is end-to-end as indicated from the difference between the two rotational diffusion constants DR = 40000 ± 20% and DR = 10000 ±30% s-1. On the basis of the Hall-Slayter model and assumption of end-to-end association we calculated the ratio of the sedimentation coefficient of single, pair and triplet associates, being 1:1.14:1.20. Therefore, it is difficult to separate them in a sedimentation run. For ionic strength below 0.05 molar and low fibrinogen concentration (0.lmg/ml) a fast decay appears in the correlation, indicating that the Brownian motion is strongly influenced by electrostatic interactions.

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