Speciation in Size and Density Fractionated Fly Ash

1985 ◽  
Vol 65 ◽  
Author(s):  
Raymond T. Hemmings ◽  
Edwin E. Berry
Keyword(s):  
Fly Ash ◽  
Power Plant ◽  
Silicate Glass ◽  
Bituminous Coal ◽  
Particle Density ◽  
High Density ◽  
Low Density ◽  
Density Fractions ◽  
Alumino Silicate ◽  
Low Degrees

ABSTRACTMorphological, chemical and mineralogical speciation of fly ash from a power plant burning sub-bituminous coal has been investigated by examination of size and density fractions. It was found that whereas, fractionation by size revealed little information as to speciation among particle types, separation of the ash into six density fractions showed major differences in properties associated with true particle density. In particular it was found that at least two types of glass co-exist in the ash: “Glass I” – a predominantly silico-aluminous glass associated with particles of low density (cenospheres); “Glass II” – a calcium alumino-silicate glass associated with high-density particles. These glasses were found to differ greatly in composition and to be characterized by shifts in the position of the 2-theta of the XRD-halo. In addition, it was shown that cryptocrystalline mullite is associated only with the low-density particles. It is proposed that particles comprising low-density fractions can be considered as glassceramics with low degrees of crystallization. Particles of high-density are better described as the products of internal lime-sinter reactions.

scholarly journals RhoA localization with caveolin-1 regulates vascular contractions to serotonin

2012 ◽  
Vol 303 (9) ◽  
pp. R959-R967 ◽  
Author(s):  
Daniel W. Nuno ◽  
Sarah K. England ◽  
Kathryn G. Lamping
Keyword(s):  
Lipid Rafts ◽  
Rho Kinase ◽  
Initial Response ◽  
Cell Types ◽  
Smooth Muscle Contraction ◽  
High Density ◽  
Low Density ◽  
Density Fractions ◽  
Caveolin 1 ◽  
Multiple Cell

Vascular smooth muscle contraction occurs following an initial response to an increase in intracellular calcium concentration and a sustained response following increases in the sensitivity of contractile proteins to calcium (calcium sensitization). This latter process is regulated by the rhoA/rho kinase pathway and activated by serotonin. In multiple cell types, signaling molecules compartmentalize within caveolae to regulate their activation. We hypothesized that serotonin differentially compartmentalizes rhoA within caveolar versus noncaveolar lipid rafts to regulate sustained vascular contractions. To test this hypothesis, we measured aortic contractions in response to serotonin in wild-type (WT) and cav-1-deficient mice (cav-1 KO). RhoA-dependent contractions in response to serotonin were markedly augmented in arteries from cav-1 KO mice despite a modest reduction in rhoA expression compared with WT. We found that under basal conditions, rhoA in WT arteries was primarily localized within high-density sucrose gradient fractions but temporally shifted to low-density fractions in response to serotonin. In contrast, rhoA in cav-1 KO arteries was primarily in low-density fractions and shifted to high-density fractions in a similar timeframe as that seen in WT mice. We conclude that localization of rhoA to caveolar versus noncaveolar lipid rafts differentially regulates its activation and contractions to rhoA-dependent agonists with greater activation associated with its localization to noncaveolar rafts. Disruption of rhoA localization within caveolae may contribute to increased activation and enhanced vascular contractions in cardiovascular disease.

Agents affecting lipid metabolism. XXXVII. Separation of rat serum lipoproteins with dextran sulfate

1969 ◽  
Vol 47 (11) ◽  
pp. 1043-1047 ◽  
Author(s):  
P. Hill ◽  
D. Dvornik
Keyword(s):  
Lipid Metabolism ◽  
Lipid Composition ◽  
Dextran Sulfate ◽  
Fundamental Difference ◽  
High Density ◽  
Low Density ◽  
Serum Lipoproteins ◽  
Rat Serum ◽  
Density Fractions ◽  
Estradiol 17Β

Dextran sulfate was used to separate rat serum lipoproteins into insoluble low-density and soluble high-density fractions. Lipid composition of the separated fractions was compared to that of lipoprotein fractions prepared by ultracentrifugation; data indicate that dextran sulfate precipitates lipoproteins with a density lower than 1.063.In rats treated with ethyl p-chlorophenoxyisobutyrate and estradiol-17β comparable, though not identical, changes in the composition of serum lipoproteins were observed with both methods of separation. The observed differences may reflect the fundamental difference in the basis of separation used by the methods. Data obtained with dextran sulfate may indicate changes in the protein moieties of lipoproteins.

scholarly journals The relation of platelet density to platelet age: survival of low- and high-density 111indium-labeled platelets in baboons

Blood ◽  
1986 ◽  
Vol 68 (2) ◽  
pp. 386-393
Author(s):  
B Savage ◽  
PR McFadden ◽  
SR Hanson ◽  
LA Harker
Keyword(s):  
Specific Radioactivity ◽  
High Density ◽  
High Yield ◽  
Low Density ◽  
Density Gradients ◽  
Continuous Linear ◽  
Survival Times ◽  
Density Fractions ◽  
Age Related

The relationship between platelet density and platelet age has been studied using continuous linear Percoll density gradients and 111In- labeling of autologous platelets in baboons. To investigate changes in platelet density during senescence in the circulation, baboons were infused with 111In-labeled autologous platelets, and blood was collected at one hour postinfusion and twice daily thereafter for six days. Platelets were isolated from these samples in high yield (greater than 95%) and separated in continuous linear Percoll density gradients following density equilibrium centrifugation. Although at one hour postinfusion the density distribution of radiolabeled platelets coincided closely with the distribution of the total platelet population, a detectable symmetrical shift toward higher densities was observed after five days. The relative specific radioactivity (RSR) of high-density platelets (1.064 to 1.067 g/mL) decreased at a slower rate than that of the total platelet population (platelets of all densities), whereas the RSR of low-density platelets (1.053 to 1.056 g/mL) showed a more immediate and rapid decrease. These results give rise to one of two interpretations: (1) low-density platelets have a shorter survival time than more dense platelets and are therefore cleared from the circulation at a faster rate, or (2) platelets of all densities increase in density upon aging in the circulation. To determine the explanation for changing RSR of different density fractions we studied the in vivo disappearance characteristics of low- and high-density 111In-labeled platelets. There were no significant differences between the mean survival times of low-density platelets (5.0 +/- 0.49 days, +/- 1 SD, n = 6), high-density platelets (4.9 +/- 0.56 days, n = 6), or control platelets representing platelets of all densities (4.9 +/- 0.38 days, n = 6). Although a slight increase in the density of all platelets during platelet senescence is indicated by these studies, we conclude that platelet density heterogeneity is not primarily a consequence of age-related changes in platelet density.

scholarly journals Membrane Localization of Motility, Signaling, and Polyketide Synthetase Proteins in Myxococcus xanthus

2003 ◽  
Vol 185 (17) ◽  
pp. 5066-5075 ◽  
Author(s):  
Vesna Simunovic ◽  
Frank C. Gherardini ◽  
Lawrence J. Shimkets
Keyword(s):  
Protein Localization ◽  
Polyacrylamide Gel Electrophoresis ◽  
Myxococcus Xanthus ◽  
Buoyant Density ◽  
High Density ◽  
Putative Hybrid ◽  
Low Density ◽  
Cellular Motility ◽  
Density Fraction ◽  
Density Fractions

ABSTRACT Myxococcus xanthus cells coordinate cellular motility, biofilm formation, and development through the use of cell signaling pathways. In an effort to understand the mechanisms underlying these processes, the inner membrane (IM) and outer membrane (OM) of strain DK1622 were fractionated to examine protein localization. Membranes were enriched from spheroplasts of vegetative cells and then separated into three peaks on a three-step sucrose gradient. The high-density fraction corresponded to the putative IM, the medium-density fraction corresponded to a putative hybrid membrane (HM), and the low-density fraction corresponded to the putative OM. Each fraction was subjected to further separation on discontinuous sucrose gradients, which resulted in discrete protein peaks for each major fraction. The purity and origin of each peak were assessed by using succinate dehydrogenase (SDH) activity as the IM marker and reactivities to lipopolysaccharide core and O-antigen monoclonal antibodies as the OM markers. As previously reported, the OM markers localized to the low-density membrane fractions, while SDH localized to high-density fractions. Immunoblotting was used to localize important motility and signaling proteins within the protein peaks. CsgA, the C-signal-producing protein, and FibA, a fibril-associated protease, were localized in the IM (density, 1.17 to 1.24 g cm−3). Tgl and Cgl lipoproteins were localized in the OM, which contained areas of high buoyant density (1.21 to 1.24 g cm−3) and low buoyant density (1.169 to 1.171 g cm−3). FrzCD, a methyl-accepting chemotaxis protein, was predominantly located in the IM, although smaller amounts were found in the OM. The HM peaks showed twofold enrichment for the type IV pilin protein PilA, suggesting that this fraction contained cell poles. Two-dimensional polyacrylamide gel electrophoresis revealed the presence of proteins that were unique to the IM and OM. Characterization of proteins in an unusually low-density membrane peak (1.072 to 1.094 g cm−3) showed the presence of Ta-1 polyketide synthetase, which synthesizes the antibiotic myxovirescin A.

scholarly journals Changes in some physical characteristics of the digesta in the reticulo-rumen of cows fed once daily

1973 ◽  
Vol 29 (3) ◽  
pp. 357-376 ◽  
Author(s):  
E. W. Evans ◽  
G. R. Pearce ◽  
J. Burnett ◽  
Susan L. Pillinger
Keyword(s):  
Dry Matter ◽  
Fine Particles ◽  
Particle Density ◽  
Matter Content ◽  
High Density ◽  
Dry Matter Content ◽  
Low Density ◽  
Coarse Particles ◽  
Minimum Concentration ◽  
Once Daily

1. Three cows were given 3, 5 or 7 kg hay once daily in a Latin-square design, and samples of digesta from four sites in the rumen and one site in the reticulum were taken at six times within the 24 h period after the feed. Dry-matter content and distribution of particle size and of particle density were measured for each sample. The changes in these measurements with time were studied. The incidence of rumination was also recorded.2. Dry-matter contents of samples ranged from 15 to 3%. Values for samples from the dorsal sacs of the rumen were considerably higher than those for samples from the ventral sites; they also changed more with time after feeding and with level of feeding.3. Particles were fractionated by sieving into six size groups with mean dimensions (mm) of 9·3 × 0·8, 4·4 × 0·6, 2·6 × 0·3, 1·6 × 0·25, 0·5 × 0·1 and smaller than 0·5 × 0·1. Coarse particles occurred at highest concentrations in the dorsal sacs of the rumen and responded to effects of time and level of feeding; smaller particles showed less response.4. Particle densities ranged from 800 g/l to 1500 g/l. The proportions of low-density particles were higher in samples from the dorsal sacs of the rumen than in samples from ventral sites; the latter samples had higher proportions of high-density particles than of low-density particles. The changes which occurred are discussed.5. The density of coarse particles tended to be low and that of fine particles tended to be high.6. Rumination started at the time of maximum concentration of particles of low density and minimum concentration of particles of high density. Conversely, rumination ended when the concentration of the low-density particles was a minimum and that of the dense particles a maximum.7. The results are discussed in relation to the possible movement of particles within the reticulo-rumen and the kinetics of particle breakdown.

scholarly journals Kinetic study of T lymphocytes after sensitization against soluble antigen. III. Potentiation and suppression of the PHA response by antigen-activated lymphocytes of low density.

1975 ◽  
Vol 142 (4) ◽  
pp. 1017-1022 ◽  
Author(s):  
J A Bash ◽  
H G Durkin ◽  
B H Waksman
Keyword(s):  
Buoyant Density ◽  
High Density ◽  
Soluble Antigen ◽  
Low Density ◽  
Constant Number ◽  
Activated Lymphocytes ◽  
Density Fractions ◽  
Lymph Node Cells ◽  
Two Populations ◽  
Pha Response

Lymph node cells of ovalbumin-sensitized rats were separated on the basis of buoyant density into fractions reciprocally enriched in cells responsive to ovalbumin or phytohemagglutinin (PHA). Recombination of high density and low density fractions in varying proportions resulted in potentiation or suppression of the DNA synthetic response to PHA in culture. The response of cultures containing equal numbers of high and low density cells was markedly greater than the sum of the two populations stimulated separately. However, when decreasing numbers of low density cells were cultured with a constant number of high density cells, profound suppression was observed.

scholarly journals IMMUNOLOGICAL MEMORY IN MICE

1970 ◽  
Vol 131 (6) ◽  
pp. 1093-1108 ◽  
Author(s):  
Johanna L'age-Stehr ◽  
Leonard A. Herzenberg
Keyword(s):  
Density Gradient ◽  
Glass Bead ◽  
High Density ◽  
Low Density ◽  
Memory Cells ◽  
Primary Immunization ◽  
Spleen Cells ◽  
Density Fractions ◽  
Significant Difference ◽  
Equilibrium Centrifugation

Plaque forming cells (PFC) of different immunoglobulin classes producing antibodies against sheep erythrocytes were separated according to their buoyant densities by means of equilibrium centrifugation in a stepwise BSA gradient. In the period of 7–10 days after immunization γM PFC are markedly enriched in fractions of low density and relatively depleted in fractions of high density. The distribution of total γG PFC shows less enrichment in the lower density fractions and less depletion in the higher density fractions. The density profile for γG2a PFC is even flatter, with a significant difference (depletion) relative to the unseparated spleen cells only in the highest density fraction. The density gradient distributions of cells able to transfer an adoptive immune response of the various immunoglobulin classes are markedly different from the PFC distribution. Cells obtained 7–10 days after immunization able to transfer an IgM response are present in the same proportions across the density gradient, whereas memory cells for γG2a obtained at this time are markedly enriched in fractions of low density and virtually depleted from high density fractions. With increasing time after primary immunization, the γG2a memory cells increase progressively in density and by 6 weeks the higher and lower density fractions have the same proportions of γG2a memory cells. The total γG (mainly γG1) memory cells by 7–10 days show slight enrichment in low density fractions and no depletion in high density fractions. The conclusions were reached that (a) memory for γG1 develops earlier than memory for γG2a and (b) that memory for anti-SRBC antibodies of different classes is carried in separate cells. When gradient fractions enriched for PFC and memory cells for all classes were completely depleted of PFC using glass bead columns, the ability of this fraction to transfer memory for all classes was not diminished. This shows that memory cells are not identical with cells secreting antibodies.

scholarly journals The relation of platelet density to platelet age: survival of low- and high-density 111indium-labeled platelets in baboons

Blood ◽  
1986 ◽  
Vol 68 (2) ◽  
pp. 386-393 ◽  
Author(s):  
B Savage ◽  
PR McFadden ◽  
SR Hanson ◽  
LA Harker
Keyword(s):  
Specific Radioactivity ◽  
High Density ◽  
High Yield ◽  
Low Density ◽  
Density Gradients ◽  
Continuous Linear ◽  
Survival Times ◽  
Density Fractions ◽  
Age Related

Abstract The relationship between platelet density and platelet age has been studied using continuous linear Percoll density gradients and 111In- labeling of autologous platelets in baboons. To investigate changes in platelet density during senescence in the circulation, baboons were infused with 111In-labeled autologous platelets, and blood was collected at one hour postinfusion and twice daily thereafter for six days. Platelets were isolated from these samples in high yield (greater than 95%) and separated in continuous linear Percoll density gradients following density equilibrium centrifugation. Although at one hour postinfusion the density distribution of radiolabeled platelets coincided closely with the distribution of the total platelet population, a detectable symmetrical shift toward higher densities was observed after five days. The relative specific radioactivity (RSR) of high-density platelets (1.064 to 1.067 g/mL) decreased at a slower rate than that of the total platelet population (platelets of all densities), whereas the RSR of low-density platelets (1.053 to 1.056 g/mL) showed a more immediate and rapid decrease. These results give rise to one of two interpretations: (1) low-density platelets have a shorter survival time than more dense platelets and are therefore cleared from the circulation at a faster rate, or (2) platelets of all densities increase in density upon aging in the circulation. To determine the explanation for changing RSR of different density fractions we studied the in vivo disappearance characteristics of low- and high-density 111In-labeled platelets. There were no significant differences between the mean survival times of low-density platelets (5.0 +/- 0.49 days, +/- 1 SD, n = 6), high-density platelets (4.9 +/- 0.56 days, n = 6), or control platelets representing platelets of all densities (4.9 +/- 0.38 days, n = 6). Although a slight increase in the density of all platelets during platelet senescence is indicated by these studies, we conclude that platelet density heterogeneity is not primarily a consequence of age-related changes in platelet density.

Quantitative defect studies in semiconductor TEM samples prepared by low angle ion milling

1995 ◽  
Vol 53 ◽  
pp. 512-513
Author(s):  
L. Mulestagno ◽  
J.C. Holzer ◽  
P. Fraundorf
Keyword(s):  
Sample Preparation ◽  
Milling Time ◽  
High Density ◽  
Low Density ◽  
Ion Milling ◽  
High Quality ◽  
Variable Angle ◽  
Major Disadvantage ◽  
Induced Defects

Due to the wealth of information, both analytical and structural that can be obtained from it TEM always has been a favorite tool for the analysis of process-induced defects in semiconductor wafers. The only major disadvantage has always been, that the volume under study in the TEM is relatively small, making it difficult to locate low density defects, and sample preparation is a somewhat lengthy procedure. This problem has been somewhat alleviated by the availability of efficient low angle milling.Using a PIPS® variable angle ion -mill, manufactured by Gatan, we have been consistently obtaining planar specimens with a high quality thin area in excess of 5 × 104 μm2 in about half an hour (milling time), which has made it possible to locate defects at lower densities, or, for defects of relatively high density, obtain information which is statistically more significant (table 1).

Scanning Electron Microscopic and Electrophoretic Observations on Barium Sulphate Used to Adsorb Clotting Factors

1975 ◽  
Vol 33 (02) ◽  
pp. 256-270
Author(s):  
R. M Howell ◽  
S. L. M Deacon
Keyword(s):  
Electron Microscopy ◽  
Factor Xa ◽  
Barium Sulphate ◽  
High Density ◽  
Low Density ◽  
Factor X ◽  
Clotting Factors ◽  
Electron Microscopic ◽  
Complementary Techniques ◽  
Scanning Electron

SummaryElectron microscopy and particle electrophoresis were found to be complementary techniques with which to complete the physical data from an earlier study on barium sulphates used to adsorb clotting factors from serum. The differences revealed by scanning electron microscopy (S. E. M.) in the physical shape of low and high density grades of barium sulphate particles appear to be of greater significance than charge as expressed by electrophoretic mobility, in determining whether or not precursor or preformed factor Xa is eluted.This conclusion was based on the finding that at pH values close to 7, where the adsorption from serum occurs, all samples with the exception of natural barytes were uncharged. However as the high-density, or soil-grade, was found by S. E. M. to consist of large solid crystals it was suggested that this shape might induce activation of factor X as a result of partial denaturation and consequent unfolding of the adsorbed protein. In contrast, uptake of protein into the centre of the porous aggregates revealed by S. E. M. pictures of low-density or X-ray grade barium sulphate may afford protection against denaturation and exposure of the enzyme site.The porous nature of particles of low-density barium sulphate compared with the solid crystalline forms of other grades accounts not only for its lower bulk density but also for its greater surface/gram ratio which is reflected by an ability to adsorb more protein from serum.Neither technique produced evidence from any of the samples to indicate the presence of stabilising agents sometimes used to coat particles in barium meals.

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