Sandwich detector

A HPLC procedure also enables a quantitation of serotonine in plasma and spinal fluid at a 5 pg.mL level after enrichment[19] in a flowthrough sandwich detector with carbon electrodes adrenaline and 1-dopa are determined ... 

As far as prevention is concerned, the improvements have involved mainly an extension of leak detection by wire on the auxiliary piping, and placing of nearly 600 new detectors called "sandwich detectors" to cover the welds on the large piping (diameter exceeding 200mm). 

Leak detection plays an important role. Wire detection has been developed in many countries. Recently Super Phenix has been equipped with "Sandwich detectors" to cover welds on the piping exceeding 200 mm in diameter, on which insulating material may react with Na and prevent it from getting into contact with the classical wire detection system. Other detection systems such as flame spectrometers and smoke detectors are commonly used. The objectives pursued are the following ... 

OSI Optoelectronics http //www.osioptoelectronics.com/standard-products/sili con-photodiodes/two-color-sandwich-detectors.aspx. OSI Optoelectronics... 

The detector in a spectrometer must produce a signal related to the intensity of the radiation falling on it. For instruments operating in the visible region a photovoltaic or barrier-layer cell is the simplest and cheapest available. Current produced when radiation falls on a layer of a semiconductor material, e.g. selenium, sandwiched between two metallic electrodes, is proportional to the power of the incident radiation and can be monitored by a galvanometer. Barrier layer cells are robust and are often used in portable instruments but they are not very sensitive and tend to be unstable during extended use. 

Fig. 31 (A) Principle of a sandwich immunoassay using FDA particulate labels. The analyte is first immobilized by the capture antibody preadsorbed on the solid phase (a) and then exposed to antibody-coated microparticle labels (b). Every microparticle contains 108 FDA molecules. High signal amplification is achieved after solubilisation, release, and conversion of the precursor FDA into fluorescein molecules by the addition of DMSO and NaOH (c). (B) Calibration curves of IgG-FDA microcrystal labels with increasing surface coverage of detector antibody (a-d) compared with direct FITC-labeled detector antibody (e). The fluorescence signals increase with increasing IgG concentration. FDA microcrystals with a high IgG surface coverage (c,d) perform better than those with lower surface coverage (a,b). (Reprinted with permission from [189]. Copyright 2002 American Chemical Society)...

Current detectors use a deuterated triglycerine sulphate (DTGS) crystal or lithium tantalate (LiTa03) sandwiched between two electrodes from which they receive the radiation. This allows monitoring of the rapid modulation of the radiation intensity. Under the effect of a potential difference, the crystal becomes pyroelectric. It is polarised and acts as a dielectric whose degree of polarisation varies with the... 

A top cross-sectional sketch of the fast neutron gauge is shown in Fig 14. The sample is sandwiched between the neutron source capsule and the window of a shielded thermal neutron detector. The actual assembly includes either a 5 curie plutonium-beryllium capsule or a 4 microgram 252 Cf capsule as the source of fast neutrons the neutron output for each source is about 107 neutrons/sec. The sample container... 

More recent versions of this design feature an added focusing system, called a radial drift chamber, in front of the detector. Gas ionization occurs within this drift chamber, which is composed of a set of concentric charged rings sandwiched between two lens-shaped metal grids. The cluster of electrons is then focused by the drift chamber, making its direction normal to the surface of the multiwire detector. 

Fig. 6.3 Scheme of an ELISA sandwich assay. Left panel A typical assay format using a 96-well microplate, pre-coated with a capture antibody (Ab). The drug analyte in the sample is bound to the immobilized capture Ab. The extraneous matrix components are washed away before addition of the detector second Ab, which is conjugated with horseradish per-... 

The absorption cell is a glass silicon glass sandwich component (15xlx 0.4 mm) where optical intensities from different colored LEDs are measured by a 64 pixel CCD detector, see also Fig. 25. A demonstrator system with a total system volume of about 50 ml is illustrated in Fig. 26. 

Acetylcholineesterase and choline oxidase The detector consisted of two Pt electrodes (6 mm x 3 mm) sandwiched between Perspex sheets and separated by a 1 mm thick sheet of silicone rubber, and the carrier stream (0.5 mL/min) was 0.1 M phosphate buffer (pH 8.2). AChE and ChO were immobilized by glutraldehyde cross-linking to controlled-pore glass and packed into columns (3 cm x 2.5 mm) that were operated at 25° C. Rectilinear calibration graphs for 10-100 pM choline and acetylcholine were obtained. [104]... 

---