Signal cleaner

Reuptake. The nerve cell that released the neurotransmitter also has what are called reuptake sites on its surface. These reuptake sites are actually transporter proteins that are specific to each type of neurotransmitter. They act like miniature vacuum cleaners to retrieve the neurotransmitter from the synapse. The neurotransmitter is removed from the synapse at the reuptake site and returned to the inside of the nerve cell s axon terminal. Although the reuptake process recycles the neurotransmitter molecules for future use, the process does, in fact, serve to terminate the current neurotransmitter signal. 

This suppression scheme has been shown to work well together with HMQC experiments of small molecules at natural abundance. Even cleaner spectra are obtained, if the BIRD sequence is combined with HSQC experiments already containing a spin-lock purge pulse. Drawbacks of the BIRD pulse scheme are the fact that the relaxation delay between scans cannot be chosen freely anymore and that complete suppression of all C-bound proton signals is impossible, if they have different relaxation times. Furthermore, the BIRD pulse scheme is not applicable to molecules in the slow motional regime, since negative NOEs between the inverted proton spins and the non-inverted C-bound proton spins would reduce the magnetization of the latter. 

As an example of specificity improvement, Fig. 5.3.3 shows the full scan and product-ion MS/MS spectrum for 8-dehydroestriol, a prenatal hallmark of a fetus affected by Smith-Lemli-Opitz syndrome (SLOS), usually found in low concentrations. When using full scan mode, the detection of the most abundant ions (m/z 412, 397, 322, and visual appearance of the full spectrum) was compromised by the high background (Fig. 5.3.3, left). In contrast, acquisition in MS/MS mode (precursor ion m/z 412) provides a cleaner mass spectrum and a superior signal to noise ratio, especially for the transition product ion m/z 322 (Fig. 5.3.3, right). 

The rotating disk is secured to the motor shaft with a collet, which ensures an eccentricity of less than 4%. The mercury contactor which allows the current to be measured, has a very low contact resistance due to its large wetted area ( cm2) and so provides a cleaner signal than usual solid-solid contactors. 

These applications can be divided into those which demand high power (e.g. ultrasonic cleaner) intermediate power (e.g. Tweeter ) and signal power (e.g. Delay line). Some examples are briefly described below. 

In window cleaners traditionally based on dilute ammonia, removing the ammonia sting does not necessarily lead to improved consumer acceptance. Consumers in some markets have come to expect the sting and regard it as a signal of product performance. On the other hand, cases have also occurred where off-odors that appeared insignificant to the experts caused a considerable drop in consumer acceptance. 

It has been postulated that Pgp acts as a so-called vacuum cleaner (49), moving compounds from the lipid bilayer into the extracellular space. A second hypothesis has been postulated where the transporter acts as a flippase (50), either moving the substrate from the inner to the outer leaflet of the membrane or locally altering membrane lipid composition such that the substrate detaches. These mechanisms support the observation that Pgp effluxes amphipatic peptides, proteins lacking signal sequences, or lipid-modified proteins from biological membranes (51). 

Fig. 7 (A) E. coli bacterial detection using planar ring resonators (a), with control channel (b). (B) Subtraction of control signal yields cleaner binding curve. Reprinted with permission from ref [30]...

A signal in hard surface cleaning that is often highlighted in commercials (especially those for glass cleaners) is the squeak. Greasy or dirty surfaces will not squeak when the surface is rubbed due to the lubrication of the surface consumers assume that a surface that squeaks is very clean. In one patent, it is claimed that the surfactant and buffer can be chosen to foster this effect in the cleaned surface [236,237],... 

Disinfection is also a benefit desired by consumers in toilet bowl cleaning. This can be achieved with quaternary ammonium surfactants, as in bathroom and allpurpose cleaners. Quats are effective bactericides at both low (1 to 4) and high (8 to 12) pH and so are compatible with very acidic toilet bowl cleaners. One of the problems with disinfection is knowing whether the product has been used at the proper dilution, and one toilet bowl cleaner formula gives the signal via a pH-dependent dye [375],... 

Quality On each transient only the desired signal is detected, avoiding the need for signal addition/subtraction in the steps of a phase cycle. Difference artefacts are thus not encountered, and the ti-noise often associated with these in 2D spectra is reduced, providing cleaner spectra. 

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