3919 WATERGATE

Other even more cunning methods have been devised to suppress the water signal in samples that have a large water content (e.g., bio-fluid samples) such as the WET and the WATERGATE pulse sequences. Other sequences have been devised to cope with signals from carbon-bound hydrogens. Some of these actually collapse the 13C satellites into the main 12C peak prior to suppression. Such a sequence would be useful if you were forced to acquire a spectrum in a nondeuterated solvent. 

Solvent suppression Suppression of a dominant and unwanted signal (usually a solvent) either directly by saturation or by use of a more subtle method such as the WATERGATE sequence. 

WATERGATE Water suppression through gradient tailored excitation. 

Fig. 7.11 J modulation in a constant time HSQC in order to measure dipolar couplings. A Watergate pulse is introduced in order to optimize water suppression. The intensity of cross peaks is given by /(7") = C cos(nJT)exp(-T/T2) The right...

It took us only a few minutes to arrive at the Gradenigo palace, which is so large and sumptuous as to make even Ca Barbolano look so-so. There were at least a dozen gondolas outside the Watergate, and... 

Violetta directed us to a Watergate opening directly onto the Rio di San Nicolo—no grandiose frontage or loggia, just an unprepossessing doorway in a plain brick wall. 

We had reached the Watergate, and I held her hand as she embarked in the gondola. 

After dropping off Violetta at the Watergate of Number 96,1 found the Maestro in his favorite chair, comparing two manuscript copies of a work by al-Kindi, the ninth-century philosopher who may be better known to you as Abu Yusuf Ya qub ibn Is-haq ibn as-Sabbah ibn omran ibn Ismail al-Kindi. This was a bad sign, because it probably meant that he had been taking his mind off his sore hips and the Strangler both. 

That was the right answer and any other would have seen me tossed out a Watergate without a gondola. She sucked in her cheeks angrily, giving herself a monkey face. Jacopo, where is Bernardo ... 

I said, The next Watergate on the right, boatman. I do thank you for the ride, clarissimo. ... 

This lady is a real lady, not a worker here. She fell and injured her arm. A doctor lives in that house where your masters are visiting. Would you be so kind as to ferry us to the Watergate ... 

Fig. 9.1. (A) Gaussian (a) and sine (b) excitation profiles. (B) Composite (G3) Gaussian pulse. (C) Train of soft pulses modified after the DANTE sequence to achieve selective off-resonance excitation. (D) Redfield 21412 sequence. (E) Binomial 11, 121, 1331, 14641 sequences. (F) JR (a) and compensated JR (or 1111) (b) sequences. (G) Watergate sequence. (H) Weft (Superweft) sequence. (I) Modeft sequence. (J) MLEV16 sequence. (K) NOESY sequence with trim pulse. (L) MLEV17 sequence with trim pulses. (M) Clean-TOCSY sequence.

Equivalently, the second gradient can be of the same sign of the first, provided that a 180° pulse is applied in between the two. In the so-called Watergate sequence [14], selective non-excitation is achieved by tailoring the 180° pulse in such a way that all frequencies but the unwanted frequency are irradiated. The simplest scheme employed a 90° x (sel) 180° (non-sel)90° JC (sel) pulse sequence (Fig. 9.1G). The selectivity increases with the length of the 90° pulses. 

I am expecting a visitor, I said. If you want to keep your eye on the back door, I ll take the Watergate. ... 

The Watergate is a three-arched loggia, whose floor is barely above the surface of the Rio San Remo at high tide. That night the tide was out, exposing a slippery carpet of weed on the watersteps. I topped up a lantern with enough oil to bum until dawn and hung it in the central arch. Then I went back in and shot all the bolts on the big doors. 

We could have run down the back stairs and gone out the servants door. It never occurred to me to do so. Instead we left by the Watergate as usual, carefully negotiating the narrow ledge along the facade of Ca Barbolano to the comer of the building and thecalle. It was easier for me than Bruno, who takes up much more space. 

The senator sent his gondolier along to ferry me home, but I found Giorgio waiting for me down at the Watergate. As I dismissed the Tirali man I felt a mad impulse to tip him a few silver ducats for two minutes of his time. The Rome offer was already making my head spin like a windmill. 

As we walked back out to the Watergate, Vasco said, If you have any sense, boy, you will start running now and not stop until you are somewhere in the hinterland of the Kingdom of Prester John, wearing a heavy beard. ... 

Lee, G.S.H., Wilson, M.A. and Young, B.R. (1998) The application of WATERGATE suppression technique for analyzing humic substances by nuclear magnetic resonance. Org. Geochem., 28, 549-559. 

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