Analytical methods for determination of aerosols by means of membrane ultrafilters. IX. Estimation of the mean pore size at the ultrafilter surfaces by means of electron microscopy

1967 ◽  
Vol 32 (5) ◽  
pp. 1983-1988 ◽  
Author(s):  
V. Hampl
Keyword(s):  
Electron Microscopy ◽  
Pore Size ◽  
Analytical Methods ◽  
The Mean

Size of pores of Kohn: influence of transpulmonary and vascular pressures

1981 ◽  
Vol 51 (3) ◽  
pp. 739-745 ◽  
Author(s):  
R. W. Mazzone ◽  
S. Kornblau
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Pore Size ◽  
Minimum Diameter ◽  
Transmission Electron ◽  
Zone Ii ◽  
The Mean ◽  
Alveolar Septa ◽  
Collateral Ventilation

We investigated the influence of transpulmonary (Ptp) and vascular pressures on the size of the pores of Kohn in primary alveolar septa. Dogs lungs, perfused and ventilated in situ, were rapidly frozen with Freon 22 in zone II or III conditions following deflation to Ptp of 5, 15, or 25 cmH2O. Frozen samples were freeze-substituted for transmission electron microscopy. Five fields containing at least one pore each were selected randomly from each section of tissue, and the minimum diameter visible in the cut section was measured. For both zone II and III conditions, as Ptp increased, mean pore size increased. The mean pore size under zone III conditions was 1.2015, 1.788, and 2.249 micrometer for Ptp of 5, 15, and 25 cmH2O, respectively. For zone 2 conditions, the corresponding values were 1.1438, 1,8757, and 2.08 micrometer. For both zones II and III, increasing capillary hydrostatic pressure had no significant effect on pore size. The results support the notion that alveolar pores can increase collateral ventilation by dynamically stretching as Ptp increases. Capillary pressure does not influence pore size probably because of collagen fibers, which surround the pore lumen. Presumably, these fibers resist encroachment of capillaries on the pore lumen as vascular pressures increase.

THE DETERMINATION OF PORE SIZE DISTRIBUTION AND SURFACE AREA FROM ADSORPTION ISOTHERMS

1955 ◽  
Vol 33 (2) ◽  
pp. 215-231 ◽  
Author(s):  
E. M. Voigt ◽  
R. H. Tomlinson
Keyword(s):  
Pore Size Distribution ◽  
Pore Size ◽  
Size Distribution ◽  
Surface Area ◽  
Pore Radius ◽  
Weighted Average ◽  
Vycor Glass ◽  
Porous Vycor Glass ◽  
The Mean

Theoretical isotherms have been developed which when compared to experimental isotherms showing hysteresis, allow the calculation of pore size, pore size distribution, and surface area of the sorbent. Interpretation of some experimental isotherms obtained with porous vycor glass shows that this system can best be represented by the "ink bottle" pore model with a Gaussian distribution of pore sizes. The mean pore radius of the porous glass is about two thirds of the Kelvin radius, and the surface area greater than that obtained from the B.E.T. theory. The Kelvin radius is interpreted as a weighted average, but the B.E.T. surface area appears more fundamentally different.

The Determination of Evolving Microstructure Using Constitutive Relationships

1999 ◽  
Vol 578 ◽  
Author(s):  
B.J. Diak ◽  
S. Saimoto
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Grain Size ◽  
Tensile Deformation ◽  
Constitutive Parameter ◽  
Upper Limit ◽  
Transmission Electron ◽  
The Mean ◽  
Slip Distance

AbstractThe evolution of the constitutive parameter, the mean slip distance, λ, is monitored during tensile deformation of 3.2 μm grain size aluminum at 200 K. Transmission electron microscopy (TEM) confirms that the grain size, D, sets an upper limit to λ.

scholarly journals Ultra-high performance liquid chromatographic determination of aflatoxin M1 in urine

2015 ◽  
Vol 8 (4) ◽  
pp. 405-413 ◽  
Author(s):  
S. Mohd Redzwan ◽  
R. Jamaluddin ◽  
A.M. Mohd Sokhini ◽  
A.R. Nurul Aqilah ◽  
A. Zuraini ◽  
...  
Keyword(s):  
Biological Samples ◽  
Analytical Methods ◽  
High Performance ◽  
Limit Of Detection ◽  
Extraction Procedure ◽  
Aflatoxin M1 ◽  
Enzyme Linked Immunosorbent Assay ◽  
Fluorescence Detector ◽  
The Mean

The development of analytical methods to detect aflatoxin B1 (AFB1) in foodstuffs and its metabolites in human biological samples is useful for risk assessment. The latter methodology, i.e. the measurement of AFB1 biomarkers, has become important to assess human aflatoxin exposure. AFB1-lysine adduct, AFB1-DNA adduct and urinary aflatoxin M1 (AFM1) are some of the AFB1 biomarkers that can be measured by several analytical methods, such as enzyme-linked immunosorbent assay, radioimmunoassay, and high performance liquid chromatography (HPLC). HPLC coupled to a fluorescence detector is useful and preferable due to its high degree of sensitivity, but the analysis may take time and consume large amount of solvents. Therefore, the present study extrapolated the HPLC method to ultra-HPLC for the determination of urinary AFM1. After the extraction procedure with an immunoaffinity column, chromatographic separation was done using a high performance 1.8 μm microparticulate C18 column. The mean recovery from urine samples spiked with 0.5, 1.0 and 2.0 ng/ml AFM1 was 84.4±4.0%, with acceptable recovery values, interday (6.0±5.3%) and intraday (2.6±0.6%) coefficients of variation. The retention time was 5.7 min. This method was used to measure urinary AFM1 in 71 subjects, of which 13 had AFM1 levels above the limit of detection (0.018 ng/ml). The mean urinary AFM1 level of the positive samples was 18.8±28.6 pg/ml, ranging from 2.4 to 100.4 pg/ml. As this is one of the few studies investigating the occurrence of aflatoxin biomarkers in human biological samples in Malaysia, a study with a larger sample size is necessary to investigate the magnitude of aflatoxin exposure among the population.

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