Super-quenching

It should also be noted that comparison of quenching efficiency of conjugated polymers with small-molecule fluorophores is complicated and oversimplification can lead to misleading claims of exceptional sensitivity enhancements. In their 2007 review, Swager and co-workers discuss cases where the charge state of the small molecule used for comparison differed fundamentally from the polymer and exceptional quenching efficiencies were inappropriately attributed to super-quenching alone [3], In addition, a polymer will create a different local... 

The principle of frustrated super-quenching as a detection technique for quantifying the catalytic activity of hydrolytic enz3mies can also be extended by using solid supported polymer and enveloping it with anionic biopolymers like carboxymethyl amylose (CMA) or carboxymethyl cellulose (CMC) to shield its fluorescence from electron transfer or energy transfer quenchers. 

This chapter describes a broad range of optical biosensor technologies, based on interchromophore interactions and the super-quenching phenomenon. Several specific biosensor schemes are described that are able to sense the activity of kinase, protease, lipase, and cellulase enzymes. Although the systems are disparate, the underlying sensor mechanisms are related, in that they all... 

Fig. 51eft. Schematic flow diagram of an ethylene plant using naphtha feedstock. CW = cooling water QW = quench water QO = quench oil LPS = low pressure steam MPS = medium pressure steam SPS = super high pressure steam C3R = propylene refrigerant and...

Furthermore, the same sol-gel matrices have been used in a system where acid and base catalysis occur in the same pot without quenching either catalyst [29]. In this case, the acids were either entrapped Nafion (perfluorinated resin sulfonic super acid, a3) or entrapped molybdic acid (M03-Si02, a2), while the bases were two ORMOSILs (organically modified silica sol-gel materials), one with H2N (CH2)2NH(CH2)3 groups (bi) and the other guanidine base residues (b2) (Scheme 5.12). 

Sulfur nitride polymers [-(-S = N-)-], which have optical and electrical properties similar to those of metals, were first synthesized in 1910. These crystalline polymers, which are super-conducive at 0.25 K, may be produced at room temperature using the solid state polymerization of the dimer (S2N2). A dark blue-black amorphous paramagnetic form of poly(sulfur nitride) (structure 11.30) is produced by quenching the gaseous tetramer in liquid nitrogen. The polymer is produced on heating the tetramer to about 300°C. 

Treatment of isopropenylacetylene with an excess of BuLi or BuLi.TMEDA does not give rise to double deprotonation, but to a slow addition with formation of an adduct With the super basic reagent BuLi.r-BuOK [45,46,52,53] in a mixture of THF and hexane, dimetallation can be accomplished in a short time at low temperatures. The high efficiency of the dimetallation appears from the excellent yield (> 90%) of MejSiCsCC(CH2SiMe3)=CH2 obtained by quenching with h SiCl. Addition of anhydrous lithium bromide converts the dipotassium compound into the dilithio derivative, which can be used for regiospecific functionalizations. 

The defect structure of Fei O with the NaCl-type structure had been estimated to be a random distribution of iron vacancies. In 1960, Roth confirmed, by powder X-ray diffraction, that the defect structure of wiistite quenched from high temperatures consists of iron vacancies (Vp ) and interstitial iron (Fcj) (there are about half as many FCj as Vpe). This was a remarkable discovery in the sense that it showed that different types of crystal defects with comparable concentrations are able to exist simultaneously in a substance, Roth also proposed a structure model, named a Roth cluster, shown in Fig. 1.84. Later this model (defect complex = vacancy -F interstitial) was verified by X-ray diffraction on a single crystal and also by in-situ neutron diffraction experiments. Moreover, it has been shown that the defect complex arranges regularly and results in a kind of super-structure, the model structure of which (called a Koch-Cohen model) is shown in Fig. 1.85 together with the basic structures (a) and (b). 

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