scholarly journals The effect of size and density on the mean retention time of particles in the reticulorumen of cattle (Bos primigenius f. taurus), muskoxen (Ovibos moschatus) and moose (Alces alces)

2010 ◽  
Vol 105 (4) ◽  
pp. 634-644 ◽  
Author(s):  
Marcus Clauss ◽  
Isabel Lechner ◽  
Perry Barboza ◽  
William Collins ◽  
Theo A. Tervoort ◽  
...  
Keyword(s):  
Particle Size ◽  
Particle Density ◽  
Alces Alces ◽  
Ovibos Moschatus ◽  
Ruminant Species ◽  
Particle Retention ◽  
Forage Type ◽  
The Mean ◽  
Filter Bed ◽  
Dependent Mechanism

Particle passage from the reticulorumen (RR) depends on particle density and size. Forage particle density and size are related and change over time in the RR. Particle density mainly influences sorting in the reticulum, whereas particle size influences particle retention in the fibre mat of stratified rumen contents (‘filter-bed’ effect). We investigated these effects independently, by inserting plastic particles of different sizes (1, 10 and 20 mm) and densities (1·03, 1·20 and 1·44 mg/ml) in the RR of cattle (Bos primigenius f. taurus) as a pilot study, and of muskoxen (Ovibos moschatus; n 4) and moose (Alces alces; n 2) both fed two diets (browse and grass). Faeces were analysed for plastic residues for 13 d after dosing to calculate mean retention times (MRT). The results confirmed previous findings of differences in absolute MRT between species. Comparing muskoxen with moose, there was no difference in the effect of particle density on the MRT between species but particle size had a more pronounced effect on the MRT in muskoxen than in moose. This indicated a stronger ‘filter-bed effect’ in muskoxen, in accord with the reports of stratified RR contents in this species v. the absence of RR content stratification in moose. Low-density particles were retained longer in both species fed on grass diets, indicating a contribution of forage type to the ‘filter-bed effect’. The results indicate that retention based on particle size may differ between ruminant species, depending on the presence of a fibre mat in the RR, whereas the density-dependent mechanism of sedimentation in the RR is rather constant across species.

scholarly journals The effect of size and density on mean retention time of particles in the gastrointestinal tract of sheep

1990 ◽  
Vol 63 (3) ◽  
pp. 457-465 ◽  
Author(s):  
M. Kaske ◽  
W. V. Engelhardt
Keyword(s):  
Particle Size ◽  
Regression Analysis ◽  
Polyethylene Glycol ◽  
Gastrointestinal Tract ◽  
Multiple Regression Analysis ◽  
Retention Time ◽  
Particle Density ◽  
Mean Retention Time ◽  
Selective Retention ◽  
The Mean

The selective retention of particles in the reticulo-rumen and in the gastrointestinal tract distal to the reticulo-rumen was studied in fistulated sheep maintained on a roughage diet. Polyethylene glycol and plastic particles of different lengths (1 and 10 mm) and densities (092, 1.03, 1.22 and 1.44 g/ml) were either fed or were introduced into the omasum. The mean retention time in the reticulo-rumen (MRTRR) of 1 mm long particles with a density of approximately 1.0 g/ml was about 67 h, that is eight times longer than the MRTRR of fluid; the heavier particles were retained only three times longer than fluid. Particles with a length of 10 mm were retained in the reticulo-rumen 19–28 h longer than 1 mm long particles of the same density. Particles with a length of 10 mm were reduced to smaller particles (0.5–4 mm) due to rumination. Multiple regression analysis indicated that particle density and particle size accounted for 59 and 28% of the total variation of MRTRR respectively. The mean retention time distal to the reticulo- rumen (MRTGut) of 1 and 10 mm long particles with a density near 1.0 g/ml was 18–19 h, similar to that of fluid (16 h). The heavier particles were retained about 3–8 h longer.

Novel Formulation Development and Evaluation of Nanoparticles Based in Situ Gelling System for The Ophthalmic Delivery of Ciprofloxacin Hydrochloride

2015 ◽  
Vol 5 (4) ◽  
Author(s):  
Kranti Singh ◽  
Surajpal Verma ◽  
Shyam Prasad ◽  
Indu Bala
Keyword(s):  
Particle Size ◽  
Zeta Potential ◽  
Drug Loading ◽  
In Vitro Release ◽  
Formulation Development ◽  
Ciprofloxacin Hydrochloride ◽  
Potential Value ◽  
The Mean ◽  
In Situ Gelling

Ciprofloxacin hydrochloride loaded Eudragit RS100 nanoparticles were prepared by using w/o/w emulsification (multiple emulsification) solvent evaporation followed by drying of nanoparticles at 50°C. The nanoparticles were further incorporated into the pH-triggered in situ gel forming system which was prepared using Carbopol 940 in combination with HPMC as viscosifying agent. The developed nanoparticles was evaluated for particle size, zeta potential value and loading efficiency; nanoparticle incorporated in situ gelling system was evaluated for pH, clarity, gelling strength, rheological studies, in-vitro release studies and ex-vivo precorneal permeation studies. The nanopaticle showed the mean particle size varying between 263.5nm - 325.9 nm with the mean zeta potential value of -5.91 mV to -8.13 mV and drug loading capacity varied individually between 72.50% to 98.70% w/w. The formulation was clear with no suspended particles, showed good gelling properties. The gelling was quick and remained for longer time period. The developed formulation was therapeutically efficacious, stable and non-irritant. It provided the sustained release of drug over a period of 8-10 hours.

Continuous Precipitation of Lead Iodide

1994 ◽  
Vol 59 (7) ◽  
pp. 1503-1510
Author(s):  
Stanislav Žáček ◽  
Jaroslav Nývlt
Keyword(s):  
Growth Rate ◽  
Particle Size ◽  
Crystal Size ◽  
Crystal Growth Rate ◽  
Laboratory Model ◽  
Lead Iodide ◽  
Secondary Nucleation ◽  
Equimolar Ratio ◽  
Continuous Precipitation ◽  
The Mean

Lead iodide was precipitated from aqueous solutions of 0.015 - 0.1 M Pb(NO3)2 and 0.03 - 0.2 M KI in the equimolar ratio using a laboratory model of a stirred continuous crystallizer at 22 °C. After reaching the steady state, the PbI2 crystal size distribution was measured sedimentometrically and the crystallization kinetics was evaluated based on the mean particle size. Both the linear crystal growth rate and the nucleation rate depend on the specific output of the crystallizer. The system crystallization constant either points to a significant effect of secondary nucleation by the mechanism of contact of the crystals with the stirrer blade, or depends on the concentrations of the components added due to the micromixing mechanism.

Batch Precipitation of Lead Iodide

1994 ◽  
Vol 59 (6) ◽  
pp. 1301-1304
Author(s):  
Jaroslav Nývlt ◽  
Stanislav Žáček
Keyword(s):  
Aqueous Solution ◽  
Particle Size ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Crystal Size ◽  
Lead Nitrate ◽  
Lead Iodide ◽  
Constant Rate ◽  
Mean Size ◽  
The Mean

Lead iodide was precipitated by a procedure in which an aqueous solution of potassium iodide at a concentration of 0.03, 0.10 or 0.20 mol l-1 was stirred while an aqueous solution of lead nitrate at one-half concentration was added at a constant rate. The mean size of the PbI2 crystals was determined by evaluating the particle size distribution, which was measured sedimentometrically. The dependence of the mean crystal size on the duration of the experiment exhibited a minimum for any of the concentrations applied. The reason for this is discussed.

scholarly journals CHARACTERISTICS AND ADSORPTION PERFORMANCE OF FORMULATED TRIKOTAC FILTER AIDS

2019 ◽  
Vol 81 (3) ◽  
Author(s):  
N. Masdiana ◽  
M. Rashid ◽  
S. Hajar ◽  
M. R. Ammar
Keyword(s):  
Particle Size ◽  
Activated Carbon ◽  
Particle Density ◽  
Adsorption Properties ◽  
The Other ◽  
Bet Surface Area ◽  
Adsorption Performance ◽  
Filtration System ◽  
Filter Aids ◽  
The Relationship

TrikotAC filter aids is a combination of a pre-coating material PreKot™ with two adsorbents; activated carbon and lime and their characteristics were investigated in this study. TrikotAC was formulated into three different weight ratios of 5:1:94, 10:1:89 and 10:5:85, respectively. The relationship between adsorption properties and characteristics of the formulated materials particle size distribution, particle density, bulk density, and BET surface area were investigated. The results showed that the adsorption capacity for TrikotAC 10:5:85 (11.88 mg/g) was higher than for the other formulated filter aids samples, and the formulated filter aids material TrikotAC showed promising characteristic as a filter aids and adsorbent for organic compound in fabric filtration system.

Improvement in Precision, Accuracy, and Efficiency in Standardizing the Characterization of Granular Materials

2013 ◽  
Author(s):  
J. R. Tucker ◽  
L. J. Shadle ◽  
S. Benyahia ◽  
J. Mei ◽  
C. Guenther ◽  
...  
Keyword(s):  
Particle Size ◽  
Distribution Density ◽  
Particle Density ◽  
Solid Particles ◽  
Minimum Fluidization Velocity ◽  
Void Fractions ◽  
Multiphase Systems ◽  
Precision And Accuracy ◽  
Accuracy And Repeatability

Useful prediction of the kinematics, dynamics, and chemistry of a system relies on precision and accuracy in the quantification of component properties, operating mechanisms, and collected data. In an attempt to emphasize, rather than gloss over, the benefit of proper characterization to fundamental investigations of multiphase systems incorporating solid particles, a set of procedures were developed and implemented for the purpose of providing a revised methodology having the desirable attributes of reduced uncertainty, expanded relevance and detail, and higher throughput. Better, faster, cheaper characterization of multiphase systems result. Methodologies are presented to characterize particle size, shape, size distribution, density (particle, skeletal and bulk), minimum fluidization velocity, void fraction, particle porosity, and assignment within the Geldart Classification. A novel form of the Ergun equation was used to determine the bulk void fractions and particle density. Accuracy of properties-characterization methodology was validated on materials of known properties prior to testing materials of unknown properties. Several of the standard present-day techniques were scrutinized and improved upon where appropriate. Validity, accuracy, and repeatability were assessed for the procedures presented and deemed higher than present-day techniques. A database of over seventy materials has been developed to assist in model validation efforts and future designs.

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 Antioxidant Activity and Phenolic Content of Campomanesia Phaea Extracts Obtained by Pressurized Liquid Extraction

2019 ◽  
Vol 11 (1) ◽  
pp. 56-65
Author(s):  
Daniele Martins Firmiano ◽  
Gabriela Marques Bittencourt ◽  
Alessandra Lopes de Oliveira
Keyword(s):  
Antioxidant Activity ◽  
Particle Size ◽  
Phenolic Compounds ◽  
Phenolic Content ◽  
Fixed Bed ◽  
Liquid Extraction ◽  
Pressurized Liquid Extraction ◽  
Total Phenolic ◽  
High Antioxidant Activity ◽  
The Mean

Objective: This research used the Pressurized Liquid Extraction process (PLE) to obtain cambuci extracts rich in phenolic compounds and, consequently, with high antioxidant activity. Methods: We determined the centesimal composition and the mean particle size of the dried and crushed sample for characterization of the fixed bed extractor. Extractions with pressurized ethanol were performed following a Central Composite Design (CCD) with temperature (60 °C at the center point with ± 10 °C amplitude) and the contact time between the solvent and the matrix (6 min at the center point with ± 2 min amplitude) as independent variables in the process. The Total Phenolic Content (TPC) of compounds and antioxidant activity were determined. Results: The mean particle size of the cambuci in the PLE was 263.4 μm with apparent and real densities of 32.42 g/cm3 and 1.62 g/cm3, respectively, resulting in a fixed bed porosity of 0.43. The centesimal composition of the comminuted and dried sample was 12.5 ± 0.1% moisture, 3.2 ± 0.2% ash, 3.35 ± 0.07% crude protein, 10.32 ± 0.08% crude fiber and 0.35 ± 0.04% ethereal extract. The highest extraction yield (41.7%) was obtained by using the binomial 70 ºC with 8 min of solvent contact in three batches. Extracts with the highest TPC (6501.10 mg AGE/100 g sample) were obtained by the binomial 74 °C with 6 min of contact; the binomial 50 °C with 4 min of contact gave rise to the extract with the highest antioxidant activity. The CCD showed high yield extracts with high antioxidant activity and a high total phenolic compound content. Conclusion: With the use of the proposed experimental design, it was possible to optimize the extraction of total phenolic compounds from the sample.

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