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At least 523 records · Page 29Linked to original sources
PubMed1999

The effect of forage source and particle size on finishing yearling steer performance and ruminal metabolism.

Two finishing trials and a metabolism trial were conducted to evaluate the effect of forage source and particle size in dry-rolled corn finishing diets. In Exp. 1, 224 crossbred yearling steers (BW = 342+/-11 kg) were used in a randomized complete block design consisting of seven treatments. Treatments were an all-concentrate diet or diets containing equal NDF levels provided by alfalfa hay or wheat straw (three treatments each) with each forage source ground to pass through a .95-, 7.6-, or 12.7-cm screen. Steers fed diets containing forage had greater (P < .05) DMI than steers fed an all-concentrate diet. Steers fed alfalfa diets gained faster (P < .05) with a greater (P < .05) concentrate efficiency than steers fed either all-concentrate or straw diets. In Exp. 2, 120 crossbred yearling steers (BW = 307+/-2 kg) were used in a completely randomized design and fed dry-rolled corn diets containing 10% alfalfa ground to pass through either a .95- or 7.6-cm screen. Alfalfa particle size had no effect on performance or carcass measurements. In Exp. 3, six ruminally fistulated steers (BW = 508+/-34 kg) were used in a 6 x 6 Latin square design and fed an all-concentrate diet or diets containing equal NDF levels provided by alfalfa hay, wheat straw, or ground corncobs with alfalfa and straw ground to pass through either a 2.54- or 12.7-cm screen. Steers fed straw diets spent more time (P < .10) chewing than those receiving the other diets. In conclusion, forage particle size had no effect on finishing cattle performance or ruminal metabolism data. However, cattle consuming different forage sources in dry-rolled corn finishing diets may not respond similarly in animal performance.

Animal Feed↗
PubMed2003

Single particle confocal fluorescence spectroscopy in microchannels: dependence of burst width and burst area distributions on particle size and flow rate.

This article presents a non-invasive, optical technique for measuring particulate flow within microfluidic channels. Confocal fluorescence detection is used to probe single fluorescently labeled microspheres (200-930 nm diameter) passing through a focused laser beam at a variety of flow rates (100 - 1000 nL/min). Simple statistical methods are subsequently used to investigate the resulting fluorescence bursts and generate single-particle burst width and burst area distributions. Analysis of such distributions demonstrates that the average burst width and burst area decrease as particle size increases. In addition, both burst width and burst area (for a given particle size) are observed to decrease as volumetric flow rate is increased. The dependence of such distributions on particle size is proposed as a potential route to sizing single particles and molecules in microfluidic systems.

Journal Article↗
PubMed1982

The importance of particle size in response to inhaled bronchodilators.

The effect of 250 micrograms terbutaline sulphate of three different particle sizes from a metered dose inhaler was examined in ten non-asthmatic and ten asthmatic subjects. Particle size ranges were approximately less than five micrometers, five to ten micrometers and ten to fifteen micrometers. Responses to the less than five micrometers range were significantly greater than those to the larger sizes in both groups of subjects. In the asthmatic patients there was a suggestion that the difference between small and large particles was more marked for V50 than sGaw reflecting poorer penetration of large particles into smaller airways.

Adolescent↗
PubMed2006

Strategy for determination of an efficient Cochleate particle size.

Cochleate structures obtained from the outer membrane of Neisseria meningitidis serotype B have demonstrated to be high immunogenicity when administrated by intramuscular, oral or intranasal routes, and could be used as adjuvant and meningococcal nasal vaccine candidate. Due to the microparticulate nature of Cochleate it is necessary to control the particle size since it capture by cells of the immune system could be affected by this aspect. We combined optic microscopy and immunisation experiments to select the optimum particle size. Six different processes of producing Cochleate obtaining were evaluated and different mechanical stress conditions were carried out to homogenize and modulate the particles size. The more immunogenic particles were selected on the basis of the levels of specific IgA and IgG antibodies induced after intranasal immunisation in mice. The best treatment parameter for mechanical stress of the Cochleate was prolonged treatment with untrasonic low frequency waves.

Adjuvants, Immunologic↗
PubMed1994

Assessment of chewing efficiency: a comparison of particle size distribution determined using optical scanning and sieving of almonds.

Particle sizes obtained with progressive chewing cycles were quantified by use of an optical scanning device and compared with the sieving method. The aim of this study was to validate the optical method by comparison with sieving using a natural test food, almond. Masticatory efficiency was assessed in six dentate subjects. The almonds were chewed for 1, 4, 8, 16 and 32 chewing strokes. Each experiment was replicated. The chewed material was sieved through a 1 mm aperture sieve on a Büchner funnel and dried after washing with water and 100% alcohol. The dried particles were weighed and scanned by an optical scanning device for number and size. The same samples were sieved and weighed with a conventional sieve method. The results of both methods were described by particle size distributions based on the volume of particles. The results derived from the optical scanning and sieving showed similarity. It can be concluded that the optical method is simple to use, faster than sieving and needs little skill in the use of equipment. The comparison of the results validates both methods.

Adult↗
PubMed1987

Influence of pore and particle size on the frontal uptake of proteins. Implications for preparative anion-exchange chromatography.

Several silica-based anion-exchange packings were synthesized with nominal pore sizes of 250, 500 and 1000 A in 10-, 20- and 50-micron particles. The static ("equilibrium") adsorption capacities for bovene serum albumin (mol. wt. 69,000), alpha-lactalbumin (17,500) and ferritin (440,000) were first measured using bulk material. The media were then packed into columns for frontal uptake experiments to measure adsorption from a flowing mobile phase. In general, frontal uptake was inversely related to both flow-rate and particle size. However, the magnitude of these relationships was strongly dependent on the pore to protein diameter ratio. More specifically, the uptake of bovine serum albumin was significantly more sensitive to linear velocity and particle size than alpha-lactalbumin. A mathematical model of the chromatographic process was used to calculate radial adsorption profiles across the chromatographic particle during frontal uptake. It was shown that restricted intraparticle diffusion due to insufficient pore size causes incomplete utilization of internal surface area. Under such conditions, protein is only bound within a finite shell on the outermost side of the particle; therefore, the effective loadability of the packing is greatly reduced. These data suggest that a pore size of at least 500 A will be required for the preparative chromatography of proteins with a molecular weight higher than ca. 100,000. This observation is especially evident when using particle sizes greater than 10 micron.

Adsorption↗
PubMed1996

Torque and histomorphometric evaluation of c.p. titanium screws blasted with 25- and 75-microns-sized particles of Al2O3.

A comparison was made between screw-shaped c.p. titanium implants blasted with either 25- or 75-microns particles of Al2O3. The implant surfaces were investigated with respect to topography and composition before implantation in rabbit bone. Grit blasting with 25- or 75-microns particles produced two different surface roughnesses, but no significant difference in the surface composition for the two surfaces. After 12 weeks insertion time in the rabbit tibia and femur, a higher removal torque and more bone-to-metal contact was found for the implants blasted with 75-microns particles compared with the 25-microns-blasted ones.

Aluminum Oxide↗
PubMed1998

Preparative electrophoresis in "sieving media" of subcellular-sized particles.

The commercial gel electrophoresis apparatus with intermittent scanning of the migration path and preparative capacity (HPGE-1000, LabIntelligence) is applicable to polymer solutions as well as gels. Unresolved rat liver microsomes can be isolated from 11-15% polyvinylpyrrolidone (PVP) solution by means of a syringe. The automated band isolation technique applied under resolving conditions in dilute polymer solutions allowed for the sequential isolation of three microsome components with 85, 76 and 75% recovery, respectively, under strict control of the dimensions of the volumetric collection module of the HPGE-1000 apparatus. Separations of unlabeled microsomes and sea urchin egg components in dilute polymer solutions have been performed, using detection by "fluorescence reduction". The unlabeled major component of a sea urchin egg homogenate has been isolated from electrophoresis in 1.5% PVP (Mr = 10(6)) solution in 25-50% yield (0.24-4 microg/8 lanes of the HPGE-1000 apparatus). However, since separations of both microsomes and sea urchin egg granules in dilute polymer solutions are restricted to a narrow range of polymer concentrations, their retardation coefficients, KR = d(log mobility)/d(polymer concentration), are not ascertained.

Animals↗
PubMed2005

Entrapment of some compounds into biocompatible nano-sized particles and their releasing properties.

Two types of biocompatible nanoparticles with an average diameter of around 200 nm were formed only by mixing hydrolysates of chitosan and carboxymethyl cellulose (CMC). Nanoparticle A was produced from chitosanase hydrolysate of chitosan and cellulase hydrolysate of carboxymethyl cellulose, and nanoparticle B was produced from lysozyme hydrolysate of chitosan and the carboxymethyl cellulose hydrolysate. Negatively charged or amphoteric compounds were first mixed with chitosan hydrolysate and then added to carboxymethyl cellulose hydrolysate to effectively entrap them in the particles. Positively charged compounds could also be effectively entrapped by mixing the hydrolysates and the compound in the reverse order. Negatively charged compounds with high molecular weights were maintained in the particles even at the higher pH levels than the pK(a) of the amino groups of chitosan. Entrapped compounds were gradually released from nanoparticle A by lysozyme treatment. In contrast, there was no release from nanoparticle B. These results indicate that nanoparticle A can be applied to controlled-release drug delivery systems, and that nanoparticle B is stably retained in the body without releasing the entrapped compounds.

Bacillus↗
PubMed2005

On-chip high-speed sorting of micron-sized particles for high-throughput analysis.

A new design of particle sorting chip is presented. The device employs a dielectrophoretic gate that deflects particles into one of two microfluidic channels at high speed. The device operates by focussing particles into the central streamline of the main flow channel using dielectrophoretic focussing. At the sorting junction (T- or Y-junction) two sets of electrodes produce a small dielectrophoretic force that pushes the particle into one or other of the outlet channels, where they are carried under the pressure-driven fluid flow to the outlet. For a 40 microm wide and high channel, it is shown that 6 microm diameter particles can be deflected at a rate of 300/s. The principle of a fully automated sorting device is demonstrated by separating fluorescent from non-fluorescent latex beads.

Cell Separation↗
PubMed1988

[Retention of large-size particles in the reticulum of the cow].

To explain the retention of large particles in the reticulum, in vitro sedimentation, sorting of particles by gas production and flow of contents through a hole simulating the reticulo-omasal orifice (ROO) were examined. Removal of large particles from the floor of the reticulum by gas production and a sieving mechanism through the ROO are discussed.

Animals↗
PubMed1966

Characterization of Mycoplasma aerosols as to viability, particle size, and lethality of ultraviolet irradiation.

Kundsin, Ruth B. (Harvard Medical School, Boston, Mass.). Characterization of Mycoplasma aerosols as to viability, particle size, and lethality of ultraviolet irradiation. J. Bacteriol. 91:942-944. 1966.-Viable aerosols of four strains of Mycoplasma: M. hominis II, M. pharyngis, M. pneumoniae, and an undetermined strain recovered from a lung at autopsy were dispersed, and the particle size was determined. The median diameter of the droplet nuclei ranged from 1.5 to 3.1 mu. M. pharyngis had a dieaway constant k of 0.008, indicating a survival potential of 6 hr from 10,000 colony-forming units at 23% relative humidity. Ultraviolet irradiation destroyed over 99% of the aerosols of all four strains concurrently with spraying. The particle size and viability of the droplet nuclei carrying Mycoplasma were consistent with the theory of airborne transmission of lower respiratory-tract infection.

Aerosols↗
PubMed2006

Size distribution of mineral aerosol: using light-scattering models in laser particle sizing.

The size distribution of semitransparent irregularly shaped mineral dust aerosol samples is determined using a commonly used laser particle-sizing technique. The size distribution is derived from intensity measurements of singly scattered light at various scattering angles close to the forward-scattering direction at a wavelength of 632.8 nm. We analyze the results based on various light-scattering models including diffraction theory, Mie calculations for spheres with various refractive indices, and T-matrix calculations for spheroidal particles. We identify systematic errors of the retrieved size distribution when the semitransparent and nonspherical properties of the particles are neglected. Synthetic light-scattering data for a variety of parameterized size distributions of spheres and spheroids are used to investigate the effect of simplifying assumptions made when the diffraction model or Mie theory is applied in the retrieval.

Journal Article↗
PubMedDate not supplied

Effect of urea on fly ash PCDD/F concentrations in different particle sizes.

The effect of urea as an inhibitor for reducing polychlorinated dibenzo-p-dioxin and dibenzofuran (PCDD/F) concentrations in flue gases was studied in a pilot scale plant, together with the effect on the particle size distribution of these compounds. Total PCDD/F concentrations decreased by a maximum of 74%, the decrease being greatest for the most highly (octa-) chlorinated isomers. The PCDD/F reduction affected all the particle size classes when an adequate amount of urea was used (1% of the fuel input), which indicates that inhibition, unlike formation, is independent of the fly ash particle size distribution.

Air Pollutants↗
PubMed2002

Effects of particle size, helium gas pressure and microparticle dose on the plasma concentration of indomethacin after bombardment of indomethacin-loaded poly-L-lactic acid microspheres using a Helios gun system.

We investigated the effects of the particle size of indomethacin-loaded poly-L-lactic acid microspheres (IDM-loaded PLA MS), the helium pressure used to accelerate the particles, and the bombardment dose of PLA MS on the plasma concentration of IDM after bombarding with IDM-loaded PLA MS of different particle size ranges, 20-38, 44-53 and 75-100 microm, the abdomen of hairless rats using the Helios gene gun system (Helios gun system). Using larger particles and a higher helium pressure, produced an increase in the plasma IDM concentration and the area under the plasma concentration-time curve (AUC) and resultant F (relative bioavailability with respect to intracutaneous injection) of IDM increased by an amount depending on the particle size and helium pressure. Although a reduction in the bombardment dose led to a decrease in C(max) and AUC, F increased on decreasing the bombardment dose. In addition, a more efficient F was obtained after bombarding with IDM-loaded PLA MS of 75-100 microm in diameter at each low dose in different sites of the abdomen compared with that after bolus bombardment with a high dose (dose equivalent). These results suggest that the bombardment injection of drug-loaded microspheres by the Helios gun system is a very useful tool for delivering a variety of drugs in powder form into the skin and systemic circulation.

Air Pressure↗