scholarly journals Temperature and Dilution Effects in Soot Mass Concentration Measurements

1983 ◽  
Author(s):  
J. A. Clark ◽  
D. W. Moser ◽  
W. D. Best ◽  
N. A. Thompson
Keyword(s):  
Mass Concentration ◽  
Liquid Fuel ◽  
Sampling Rate ◽  
Dilution Ratio ◽  
Nitrogen Injection ◽  
Soot Mass ◽  
Nitrogen Dilution ◽  
Dilution Effects ◽  
Nitrogen Sample ◽  
Sample Dilution

Measurements are made of soot mass concentration in a luminous, liquid fuel spray, diffusion flame at atmospheric pressure. Intrusive sampling probes are used to study the effects of sampling rate, cooling, nitrogen-dilution ratio, and tip geometry on the mass of soot particles deposited on filters. Probe diameters have been kept small to minimize disturbance to the flow-field. Relative soot concentrations are observed to be lowest for uncooled probes, higher for water-cooled probes and still higher for probes with both water cooling and nitrogen injection. Furthermore, soot concentration steadily rises as the nitrogen/sample dilution ratio is increased from zero to as high as 1.5. Sampling rate has little effect on soot concentrations under most, but not all, sampling conditions.

Factors affecting the reliability of the McMaster technique

1986 ◽  
Vol 60 (4) ◽  
pp. 260-262 ◽  
Author(s):  
Alison Dunn ◽  
Anne Keymer
Keyword(s):  
Salt Solution ◽  
Time Interval ◽  
Dilution Ratio ◽  
Laboratory Procedure ◽  
Heligmosomoides Polygyrus ◽  
Factors Affecting ◽  
Faecal Material ◽  
Mcmaster Technique ◽  
Sample Dilution ◽  
Normal Laboratory

ABSTRACTFactors detraction from the reliability of faecal egg counts based on the McMaster technique include variation in flotation time (interval between loading chamber and counting eggs) and sample dilution (ratio of faecal material to salt solution). We recommend standardization of both these variables as normal laboratory procedure, and propose optima of a 30 minute flotation time and a sample dilution of 15 ml salt solution/ g faeces for use of the McMaster technique in the estimation of the fecundity of Heligmosomoides polygyrus (Nematoda).

scholarly journals Comparison of Dilution on Eastern Box Turtle (Terrapene carolina carolina) and Marine Toad (Rhinella marinus) Blood Parameters as Measured on a Portable Chemistry Analyzer

2020 ◽  
Vol 2020 ◽  
pp. 1-7
Author(s):  
John A. Griffioen ◽  
Devorah M. Stowe ◽  
Macy Trosclair ◽  
Larry J. Minter ◽  
Chelsey Vanetten ◽  
...  
Keyword(s):  
Sample Volume ◽  
Total Carbon ◽  
Ionized Calcium ◽  
Dilution Ratio ◽  
Sample Collection ◽  
Clinical Tool ◽  
Terrapene Carolina ◽  
Two Samples ◽  
Terrapene Carolina Carolina ◽  
Sample Dilution

Biochemical testing is an important clinical tool in evaluating the physiology of reptiles and amphibians. Suitable point of care analyzers can allow for rapid delivery of results, but small patient size can inhibit sufficient sample collection. This study evaluated the utility of sample dilution with sterile distilled water as a means of biochemical evaluation when sample volume is limited. Blood was collected from 12 eastern box turtles (Terrapene carolina carolina) and 12 marine toads (Rhinella marinus) and analyzed via i-STAT CHEM8+ cartridges. Two undiluted samples and two samples diluted 1 : 1 with sterile water were evaluated immediately following collection for each animal in the study. Analytes reported in the diluted samples were limited to glucose, ionized calcium, and total carbon dioxide. The expected dilution ratio value of diluted to undiluted samples was 0.5, of which glucose in both turtles and toads was nearest. Dilution ratio values for ionized calcium, however, were higher than expected in both turtles and toads. Sample dilution is not recommended for most analytes included on the CHEM8+ cartridge due to values occurring outside the limits of detection for the analyzer. Glucose and ionized calcium values obtained on diluted samples should be interpreted with caution but may provide clinical utility in reptile and amphibian patients where sample volume is limited.

Chemical Isotope Dilution for 14C Ams and the Potential for GC/AMS

Radiocarbon ◽  
1986 ◽  
Vol 28 (3) ◽  
pp. 1065-1067 ◽  
Author(s):  
Richard Gillespie
Keyword(s):  
Radiocarbon Dating ◽  
Minimum Sample Size ◽  
Dilution Ratio ◽  
Combustion Gas ◽  
Ams Radiocarbon Dating ◽  
Beta Counting ◽  
Careful Measurement ◽  
Environmental Work ◽  
Sample Dilution ◽  
Gas Pressures

The advent of accelerator-based mass spectrometry (AMS) radiocarbon dating has reduced the minimum sample size required to ca 1 mg from the 1 g of traditional beta counting techniques (cf Wölfli, Polach & Andersen, 1984). However, it is clear that even smaller samples will be necessary for some fields of endeavor, particularly environmental work where the absolute quantities are small, perhaps of the order of a few micrograms (Currie et al, 1985). This raises serious problems in the handling and measurement of such small amounts, so that dilution will sometimes be required. Normally, sample dilution is accomplished by adding “dead” CO2 to the combusted sample CO2, which requires very careful measurement of two gas pressures for the calculation of a dilution ratio. By forming a chemical derivative of a sample before combustion, gas pressure measurement is not necessary and an exact dilution ratio can be selected by judicous choice of the dilution reagent. This paper demonstrates that such a technique is possible for the AMS 14C dating of derivatized amino acids.

Direct determination of therapeutic concentrations of lithium in serum by flow-injection analysis with atomic absorption spectroscopic detection.

1982 ◽  
Vol 28 (3) ◽  
pp. 440-443 ◽  
Author(s):  
B F Rocks ◽  
R A Sherwood ◽  
C Riley
Keyword(s):  
Atomic Absorption ◽  
Flow Injection ◽  
Direct Determination ◽  
Injection System ◽  
Analytical Recovery ◽  
Flow Injection System ◽  
Dilution Effects ◽  
Sodium And Potassium ◽  
Sample Dilution

Abstract In this flow-injection system for direct determination of lithium in serum by atomic absorption spectroscopy, the 10-microL sample is manually injected into a continuously flowing non-segmented stream of de-ionized water, which is pumped, via a dispersion tube, to the spectrometer's nebulizer. Controlled dispersion of the sample zone, before it is introduced into the nebulizer, produces the required sample dilution. Effects of varying the length of the dispersion tube, the flow rate, and the sample size were studied. Analytical readout is obtained, in the form of transient peaks, 5 s after sample injection. It is necessary to include physiological concentrations of sodium and potassium in the standard because each of these cations enhances the lithium absorbance signal. Analytical recovery (98.5 to 101%) and CV (about 2%) are good, and results compare well with those obtained by aspiration of prediluted samples (n = 121, r = 0.99).

Effects of N2/CO2 dilution on flame propagation velocities and quenching distances of oxy-methane premixed mixtures using an Annular-Stepwise-Diverging-Tube (ASDT)

2018 ◽  
Vol 13 (6) ◽  
pp. 55
Author(s):  
Hun Young Kim ◽  
Jiseop Lee ◽  
Nam Il Kim
Keyword(s):  
Flame Propagation ◽  
Burning Velocity ◽  
Thermal Capacity ◽  
Dilution Ratio ◽  
Flame Propagation Velocity ◽  
Active Involvement ◽  
Quenching Distance ◽  
Dilution Effects ◽  
Gas Recirculation ◽  
The Relationship

Many combustion systems use the technique called exhaust gas recirculation. Thus, the effects of N2/CO2 dilution on the combustion characteristics have been of interest. In this study, the dilution effects on the flame propagation velocity (FPV) of an oxy-methane premixed mixture were investigated using a state-of-the-art annular stepwise diverging tube. The relationship between FPV and the length scale was measured for various equivalence ratios in the dilution ratio range 65–75% N2 and 50–65% CO2. The characteristic variations of FPV in each dilution case could be described as a surface in a concentration–length–velocity diagram, and this provides a bird’s eye view of the dilution effects on flame propagation. Two distinctive scalar values of the quenching distance and the critical FPV were investigated. At the same dilution ratio, CO2 dilution caused more significant variation than N2 dilution did regarding FPV, quenching distance, and flammable limits. In particular, the critical FPV was compared with the laminar burning velocity (LBV) calculated using a PREMIX code employing GRI-3.0. In addition, fictitious species (F-N2/F-CO2) were used in the reaction mechanism to distinguish chemical effects. Conclusively, results showed that CO2 dilution reduced LBV significantly not only by its larger thermal capacity but also by its active involvement in the chemical reaction.

scholarly journals Inflated false-negative rates in pooled RT-PCR tests of SARS-CoV-2

2020 ◽  
Author(s):  
Yair Daon ◽  
Amit Huppert ◽  
Uri Obolski
Keyword(s):  
Infected Individual ◽  
False Negative ◽  
False Negative Rate ◽  
Infection Prevalence ◽  
Policy Makers ◽  
Trade Off ◽  
Dilution Effects ◽  
Parameter Values ◽  
Positive Results ◽  
Sample Dilution

AbstractBackgroundPooling is a popular strategy for increasing SARS-CoV-2 testing throughput. A common pooling scheme is Dorfman pooling: test N individuals simultaneously. If the first test is positive — retest each individual.MethodsUsing a probabilistic model, we analyze the false-negative rate (i.e., the probability of a negative result for an infected individual) of Dorfman pooling. Our model is conservative in that it ignores sample dilution effects, which can only worsen pooling performance.ResultsWe show that one can expect a 60-80% increase in false-negative rates under Dorfman pooling, for reasonable parameter values. Moreover, we show that the false-negative rates under Dorfman pooling increase when the prevalence of infection decreases.DiscussionIn most pooling schemes, identifying an infected individual requires positive results in multiple tests and hence substantially deteriorates false-negative rates. Furthermore, this phenomenon is more pronounced when infection prevalence is low — exactly when pooling is most efficient. Thus, pooling presents an inherent trade-off: it is most efficient when it is least accurate. The deterioration of false-negative rates and the aforementioned trade-off are inherent problems of pooling schemes and should be kept in mind by practitioners and policy makers.

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