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Published in Raj Bawa, János Szebeni, Thomas J. Webster, Gerald F. Audette, Immune Aspects of Biopharmaceuticals and Nanomedicines, 2019
Raj Bawa, János Szebeni, Thomas J. Webster, Gerald F. Audette
The cut point should be determined statistically with a minimum of 50 samples tested on at least 3 different days by at least two analysts using suitable statistical methods. FDA recommends that the cut point for screening assays be determined by a 90% one-sided lower confidence interval for the 95th percentile of the negative control population (Shen, Dong, et al., 2015). This will assure at least a 5% false-positive rate with a 90% confidence level. This approach improves the probability of the assay identifying all patients who may develop antibodies. The statistical method used to determine the cut point should be based on the statistical distribution of the data. For example, the 95th percentile of the normal distribution is estimated by the mean plus 1.645 standard deviation. Other approaches may be used for estimating 95th percentile, including the use of median and median absolute deviation value instead of mean and standard deviation.
Solid—Fluid Systems
Published in Enrique Ortega-Rivas, Unit Operations of Particulate Solids, 2016
Due to the complicated flow conditions in air classifiers, the classifying results with the given values of speed and air throughputs cannot be predetermined. For this reason, the assignment of cut point and operating data of the classifier are determined by experiments with a calibration curve. The various particle sizes of a given material of known distribution are used to plot the calibration plot. These particle sizes are separated under certain conditions of speed and air throughput. The coarse fraction is weighed at the same time. The particle size corresponding to the coarse grain proportion and legible from the fineness characteristics is the cut point according to the operating conditions of the individual classifier, also known as analytical cut point. For inert materials with densities of the order of 2600 kg/m3, cut points between 1 and 100 pm are obtained with a “normal” air throughput (0.5-3 kg/h) and by varying the speed between 2500 and 20,000 rpm. Figure 10.10 shows a calibration curve for these variables. Within these ranges, the volumetric flow rate of air V is related to the peripheral velocity N by the following expression: V=55−N1000 where Vis expressed in m3/h and N in rpm.
Evaluation of Methods Used to Generate and Characterize Jet Fuel Vapor and Aerosol for Inhalation Toxicology Studies
Published in Mark L. Witten, Errol Zeiger, Glenn D. Ritchie, Jet Fuel Toxicology, 2010
Raphaël T. Tremblay, Sheppard A. Martin, Jeffrey W. Fisher
While optical measurement techniques have potential, the most common instrument for aerosol size characterization in this field of research is the cascade impactor. Impactors differentiate particle size based on their aerodynamic diameters using geometry and gas flow. Particles larger than a given aerodynamic diameter impact a surface while particles smaller than that given diameter will stay in the gas stream. The cut point (aerodynamic diameter) is defined as the diameter where 50% of the particle impacts. A cascade impactor consists of a number of individual impactors in series with reducing cut sizes. The resulting impactor provides a series of samples, each from a different size range. These samples can then be weighted or extracted for further analysis.
Beneficiation of small South African coal using an air dense medium fluidized bed
Published in International Journal of Coal Preparation and Utilization, 2020
ES (Peters) Diedericks, M Le Roux, QP Campbell, N Hughes
A density profile of each particle size range was obtained by doing a float-sink analysis using zinc chloride solutions, for a range of 1.5 to 1.8 g/cm3 (SANS 7936:2010). From this, the separability index (Dx) was calculated to quantify the amount of near dense material between the limits of the specified relative density values (Van der Walt 1984). This refers to the mass percentage of material within a ± 0.1 range around the proposed cut point density (x). A Dx value exceeding 25 is indicative of a more challenging separation, whereas a low Dx (below 25) index refers to an easier separating coal (Van der Walt 1984). Table 3 shows the degree of difficulty for each size fraction at a number of proposed cut point densities. In general, this coal can be considered a difficult coal to beneficiate, which is typical of a Southern Hemisphere coal.
Potential of the dense media cyclone for gold ore preconcentration
Published in Mineral Processing and Extractive Metallurgy, 2020
N. P. Mkandawire, T. McGrath, A. Bax, J. Eksteen
The plot of the partition number versus the separation densities is described by two terms called the ‘cut-point’ (ρ50) and the ‘Ecarte Probable’ (Ep) also known as the probable error. The cut-point is the density at which material divides equally between the sinks and the floats while the Ep is the empirical measure of the inefficiency of the separation that looks at the area of the curve between 25% and 75% (Wills and Finch 2016).
A Detailed study of Applying Gravity Separation to Lead and Zinc Carbonate Ore for Smithsonite Concentration Using DMC
Published in Mineral Processing and Extractive Metallurgy Review, 2020
Ali Ebtedaei, Akbar Farzanegan
First, the separating density or cut point () which is defined as the density at which the partition function has the value 50%. The cut point is an operating parameter that can be controlled easily by changing the medium density and obviously determines which particles tend to sink in the medium and which particles tend to float.