Amplification common base

The common-base circuit for an npn transistor (Fig. 9.19A) seems logical and simple, but its efficiency in amplification is not obvious and must be explained. The npn transistor in a common-emitter circuit (Fig. 9.19B) is a bit easier to understand as a current amplifier. There are four rules ... 

The design concept of chemical amplification is based on generation of a chemically stable catalytic species (commonly referred to as a photoacid and designated as a proton H, as illustrated in Fig. 17.22 for a resist system comprising a copolymer—poly(4-hydroxystyrene-co-4-t-butyloxycarbonyloxystrene)—in... 

When a tramsistor is to be used in an electronic device, one of its terminals is connected to the input and the second serves as the output the third terminal is connected to both and is the common terminal. Three configurations are thus possible a common-emitter, a common-collector, and a common-base. The common-emitter configuration has the widest application in amplification and is the one we consider in detail. 

Note 2 The term chemical amplification is commonly used in photoresist lithography employing a photo-acid generator or photo-base generator. 

Fig. 21.4. Schematic representation for the detection of Salmonella through (1A) a rapid verification of PCR amplification based on the doubly labelled PCR product detection and (IB) real-time PCR reactor based on PCR amplification with magnetic bead primers on streptavidin-modified magnetic beads. (2) Enzymatic labelling (3) magnetic capture of the modified magnetic beads by the magneto electrode (m-GEC) and (4) chronoamperometric determination are common steps for all of these strategies (1A, IB).

The Allele-Specific Amplification Assay (ASA) assay is based on the fact that Taq polymerase will not initiate amplification from a primer that has a mismatch at the 3 ends. Two primers are designed so that the 3 base of the primer corresponds to the site of the genetic mutation to be tested, with either the normal or the mutant sequence at the 3 base positions. An unknown sample can then be tested for the presence of the mutation by using both the normal and the mutant primers in PCR with a common reverse primer. If the sample contains only normal sequence, a PCR product will only be produced when the normal primer is used, and similarly when the sample contains mutant sequence a product will only result from use of the mutant primer. Like the PCR-restriction enzyme method discussed, the ASA approach has also been applied to the detection of mutations in the CYP2D6 gene (16). 

Modem Ti Sapphire based femtosecond laser oscillators have been the most important technical advance for performing almost all types of femtosecond time-resolved measurements [139]. The Ti Sapphire oscillators are tunable over a 725-1000 nm wavelength range, have an average output power of several hundred milliwatts or greater and can produce pulses as short as 8 fs, but more commonly 50-130 fs, at repetition rates of 80-100 MHz. Broadly tunable femtosecond pulses can be derived directly from amplification and frequency conversion of the fundamental laser frequency. 

---