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Lateral Flow Assays
Published in Sibel A. Ozkan, Bengi Uslu, Mustafa Kemal Sezgintürk, Biosensors, 2023
Kamil Żukowski, Marcin Drozd, Robert Ziółkowski, Mariusz Pietrzak, Katarzyna Tokarska, Adam Nowiński, Elżbieta Malinowska
Regarding analytical performance indices it is particularly important to consider several parameters. Since the most typical LFA (for example LFA based rapid antigen test) has no potentization of the analytical signal, the bioreceptor targeted the biological analyte does not amplify the signal generated by the measurement. So, for the typical end-user the key parameter of the LFA is LOD. Limit of detection determines the lowest detectable concentration of targeted analyte at which 100% of all (true positive) replicates give the positive result. The next analytical characteristic parameter directly influencing the suitability of the LFA in the real life is the cross-reactivity (often called analytical specificity). The analytical specificity describes interference of a given test against a panel of related chemicals, pathogens, high prevalence disease agents and normal or pathogenic flora including various microorganisms and viruses, and negative matrix that is reasonably likely to be encountered in the clinical sample and could potentially cross-react or interfere with the desired LFA test. An important effect in the sandwich immunological LFA tests is hook effect, where at very high concentrations of tested analyte, the biorecognition elements are saturated and the signal is off (110). In practice high dose hook effect determines the level at which false negative results can be seen when very high levels of the target are present in a tested sample.
Detection Technology
Published in Rick Houghton, William Bennett, Emergency Characterization of Unknown Materials, 2020
Rick Houghton, William Bennett
Samples containing a higher concentration of antigen (agent) than marked antibodies can cause a false-negative, which is sometimes referred to as the “hook effect.” In this case, a high proportion of agent remains unmarked compared to the relatively few that bond to all available marked antibodies. The unmarked antigen is able to occupy bonding sites in a competitive manner and prevents the marked antibodies from concentrating to a visible amount in the test result strip. Hook effect usually occurs in tests involving toxins rather than organisms.
Separation performance of a hydrocyclone with a spiral guide feeding body structure using the response surface method
Published in International Journal of Coal Preparation and Utilization, 2023
Yuekan Zhang, Mingyuan Xu, Lanyue Jiang, Xinghua Yang, Meng Yang
Figure 7 shows the comparison results of classification efficiency curves of the conventional tangential inlet hydrocyclone and the hydrocyclone with a spiral guide body structure. Table 3 shows the comparison results of relevant evaluation indexes. As observed, the separation accuracy of the hydrocyclone with a spiral guide feeding body structure was significantly higher than that of the conventional hydrocyclone, and the steepness index increased from 0.247 to 0.402, while the split ratio decreased from 0.097 to 0.085. Meanwhile, a significant “fish-hook effect” was found on the classification efficiency curve for the fine particles. The researchers’ view of this anomaly was roughly divided into two groups. The first group(Zhu and Liow 2014) believed that the “fish-hook effect” was caused by the agglomeration of fine particles in the underflow and was unavoidable. The second group(Guimares, Klein, and Medronho 2020) believed that this was a random phenomenon caused by poor measurement accuracy. The classification efficiency curve was calculated by repeated experiments, and the shape of the “fish-hook effect” curve was consistent with the previous description. Therefore, the authors agreed with the view of the first group, which was a “reasonable” phenomenon commonly observed in the calculation of the classification efficiency of the hydrocyclone.
Payload motion control for a varying length flexible gantry crane
Published in Automatika, 2021
Tung Lam Nguyen, Hong Quang Nguyen, Minh Duc Duong
The gantry crane operates and deforms in one plane only.Hooke's law is applied to the gantry cable elongation deformation.The system friction is totally ignored.Hook effect between the gantry cable and payload is not considered.The payload is modelled as a point-mass i.e. payload geometry is not taken into account.Deflection angle from vertical Z axis is very small.
A survey on parameter identification, state estimation and data analytics for lateral flow immunoassay: from systems science perspective
Published in International Journal of Systems Science, 2022
Han Li, Peishu Wu, Nianyin Zeng, Yurong Liu, Fuad E. Alsaadi
Existing immunochromatographic quantitative detection methods generally collect information at a set time point and carry out the analysis, however, the biochemical reaction therein is a complicated dynamic process, which is susceptible to various uncertainties in experimental environment. Moreover, due to the Hook effect, selection of the assay time point is crucial which affects both accuracy and robustness. To tackle above issues, a series of dynamic quantification methods of immunochromatographic assay have been proposed.