Basis for Detection

Survey of Non-Neutron-Based Nuclear Detection Methods 

Problems with the Use of Nuclear Techniques for Explosive Detection 

Aspects of Explosives Detection M. Marshall andJ.C. Oxley (Editors) 

The following sections present a summary of the physics that underlies the nuclear detection technologies, a survey of neutron-based detection approaches, and an overview of non-neutron-based nuclear detection technologies. 

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As the result of high specificity and sensitivity, nucleic acid probes are in direct competition with immunoassay for the analytes of some types of clinical analytes, such as infectious disease testing. Assays are being developed, however, that combine both probe and immunoassay technology. In such hybrid probe—immunoassays, the immunoassay portion detects and amplifies the specific binding of the probe to a nucleic acid. Either the probe per se or probe labeled with a specific compound is detected by the antibody, which in turn is labeled with an enzyme or fluorophore that serves as the basis for detection. 

Milk consists of 85—89% water and 11—15% total soflds (Table 1) the latter comprises soflds-not-fat (SNF) and fat. Milk having a higher fat content also has higher SNF, with an increase of 0.4% SNF for each 1% fat increase. The principal components of SNF are protein, lactose, and minerals (ash). The fat content and other constituents of the milk vary with the animal species, and the composition of milk varies with feed, stage of lactation, health of the animal, location of withdrawal from the udder, and seasonal and environmental conditions. The nonfat soflds, fat soflds, and moisture relationships are well estabhshed and can be used as a basis for detecting adulteration with water (qv). Physical properties of milk are given in Table 2. 

To improve the public acceptance of hydrogen, it is important to understand the current perception of hydrogen by the broad public so that conclusions can be made by producers. Knowledge about the current state of social acceptance is a basis for detecting improvement points to increase it in future. 

It has seemed desirable to try to detect the postulated acylimidazole intermediate by spectroscopic probing. Acetylimidazole has been shown31 to have an absorbance maximum at 245 nm with an extinction coefficient of 3000. This absorbance should provide a basis for detection of the intermediate. However, in practice the strong absorbances due to the aromatic ester substrate (nitrophenyl caproate) and the product (nitro-phenol(ate)), added to the light scattering from the polymer, have made the spectrophotometric observation of the acylimidazole intermediate unfeasible under the reaction conditions previously described.26... 

Most commonly, uv or uV Is spectroscopy is used as ihe basis for detection in hplc. When using a chiral stationary phase, confirmation of a chiral separalion may be obtained by either monitoring the column effluent at more than one wavelength or by running the sample more than once. Although not absolute proof of a chiral separalion. this approach does provide strong supporting evidence. 

Kynureninase is involved in the oxidative metabolism of tryptophan. It catalyzes the conversion of L-kynurenine to anthranilic acid. The enzyme also converts L-3-hydroxykyneurenine to 3-hydroxyanthranilic acid. The latter compound has a high fluorescence, which is the basis for detection in this assay. 

Creatinine, a notable exception, is not reabsorbed by the tubules. All of the creatinine entering Bowman s space enters the bladder, without being reabsorbed and reentering the bloodstream. The amount of creatinine found in the urine thus accurately reflects the GFR. Tn medical practice, plasma and urinary creatinine levels are used on a day-to-day basis for detection of renal diseases. Figure 4JJ7, a diagram of the glomerulus, illustrates the flow of fluids to the urinary bladder. 

There are a number of electrochemical interactions which may be useful as the basis for detection in HPLC the most commonly used electrochemical detectors are based on amperometric measurements. The principle of operation of an amperometric detector is the oxidation or reduction of analyte in a flow-through electrolysis cell with a constant applied electrical potential, e.g. the oxidation of hydroquinone. 

Depledge, M.H. (1989) The rational basis for detection of the early indicators of marine pollutants using physiological indicators. Ambio, 18, 301-302. 

The phase transition is accompanied by the change in substance density up to an order of magnitude. This provides a basis for detection of the boiling-up... 

Catherine C. Fenselau is a professor of chemistry and biochemistry at the University of Maryland, College Park. She has been a pioneer in the application of mass spectrometry in biomedical research. Her current interests include the use of proteomic strategies to investigate cellular mechanisms of acquired drug resistance and as the basis for detection and analysis of... 

A number of biosensors utilize whole cells or specific tissues as the basis for detection (table 8.7). Cell immobilization utilizes methods such as adsorption, entrapment, and covalent bonding. The primary consideration in cell immobilization is to restrict (contain) the ceils to the sensor while not destroying them during the process of immobilization. 

Rg. 3.11. Peak-to-peak noise level as a basis for detection limit. The background fluctuations represent continuously recorded background signals, with the analyte measurement represented by the peak signal. A detectable analyte signal would be 12 divisions above a line dravra through the average of the baseline fluctuations. 

Figure 4.28. (Top) Emission spectra of [Ru(phen)2dppz] + covalently attached to single-stranded DNA by itself (single line), in the presence of noncomplementary DNA (single line-I-single line), and in the presence of complementary DNA (double lines). (Bottom) Scheme showing the basis for detection. [Adapted from Fig. 1 and Scheme 1 of Ref. 306.]...

If the nucleotide sequence of the desired DNA segment is not known and no probe is available, a complication arises. If the gene of interest directs the synthesis of a given protein, one chooses a vector that allows cloned genes to be transcribed and translated. If the presence of the desired protein can be detected by its function, that serves as the basis for detecting it. Alternatively, labeled antibodies can be used as a basis for protein detection. 

The presence of different receptor neuron types forms the basis for detection of and discrimination among odorants in the environment. In addition, important processing of the information takes place in the brain, resulting in the behavioral responses. The three olfactory areas of the insect brain are the antennal lobe, the mushroom bodies (important in learning and memory), and the lateral... 

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