Search

Your search keyword '"Ashman, M. R."' showing total 4 results
Start Over Author "Ashman, M. R."
4 results on '"Ashman, M. R."'

2. The effect of iron concentration, hindered settling, saturating cation and aggregate density of clays on the size distribution determined by gravitation X-ray sedimentometry

Author

Watts, C. W., Whalley, W. R., Bird, N. R. A., and Ashman, M. R.

Subjects
Soil Science
Abstract

X-ray sedimentation is potentially attractive for estimating the particle-size distribution of soil, but has been thought to overestimate clay fractions because of the iron they contain. We have examined X-ray sedimentation for estimating the particle-size distribution of fully dispersed and of aggregated clay. We obtained good agreement between the pipette and X-ray sedimentation methods using two different kaolinite samples with a small iron concentration. We also studied montmorillonite saturated with Li, Na, K, Mg or Ca to investigate possible effects of hindered settling. For the Ca montmorillonite, we obtained good agreement between X-ray sedimentation and the pipette method at concentrations up to 40 g l(-1). We also found that X-ray sedimentation could be used at concentrations less than those recommended by the manufacturer. Hindered settling was observed at concentrations > 20 g l(-1) for Li- and Na-saturated montmorillonite. Our data suggest that conducting experiments at different mass concentrations is a sensitive test to detect such problems. Finally we used a fractal model to investigate the possible errors that might result from the size dependence of aggregate density and show that the error caused by assuming a single value for particle density of solids is small.

Published
2000

4. Use of whole blood methods in assessment of immune parameters in immunodeficiency states.

Author

Fletcher MA, Baron GC, Ashman MR, Fischl MA, and Klimas NG

Subjects
Adult, Antibodies, Monoclonal, Antigens, Differentiation, T-Lymphocyte, Antigens, Surface analysis, Blood Preservation, Female, Flow Cytometry, Fluorescent Antibody Technique, Humans, Killer Cells, Natural analysis, Male, Mitogens pharmacology, AIDS-Related Complex immunology, Acquired Immunodeficiency Syndrome immunology, Blood, Cytotoxicity Tests, Immunologic methods, Immunologic Deficiency Syndromes immunology, Lymphocyte Activation drug effects
Abstract

Whole blood (WB) methods requiring less than 4 ml heparinized peripheral blood were used to define mononuclear cell phenotype, lymphocyte proliferation, and natural cell-mediated cytotoxicity (CYT) in samples from normal controls and patients with immunodeficiency states of acquired immunodeficiency syndrome (AIDS) and AIDS-related complexes (ARC). Results from two-color direct immunofluorescence staining of blood samples with monoclonal antibodies (Mabs) conjugated to phycoerythrin (PE) or to fluorescein isothiocyanate (FITC) and flow cytometry for the determination of mononuclear cells reactive with T11, T4, T8, B1, and NKH.1 surface markers were compared to one-color indirect immunofluorescence analysis with unlabeled Mabs and FITC-labeled goat anti-mouse IgG and flow cytometry. We found that two-color analysis was as sensitive as one-color analysis in detecting abnormal subset distribution in the patient groups. Functional properties of mononuclear cells (MNC) in WB samples and after density gradient separation were studied by mitogen-induced lymphocyte proliferation and CYT. Although the means of the groups studied varied depending on method used, results using WB methods clearly delineated the expected differences between the immunodepressed patients and normal subjects. The effects of sample storage on results obtained with WB methods for surface marker analysis, lymphocyte proliferation, and natural killer activity were also examined.

Published
1987

Catalog

Books, media, physical & digital resources
See catalog results