For coupling

However, oil was wanted for coupling to avoid problems with water deposits left on the tubes after inspection. Therefore, a measuring series was made using different couplings fluids and two different transducers (10 and 20 MHz). 

Farrar T C and Stringfellow T C 1996 Relaxation of transverse magnetization for coupled spins Encyclopedia of Nuclear Magnetic Resonance ed D M Grant and R K Harris (Chichester Wiley) pp 4101-7... 

The fimdamental disadvantage of the mean-field method is that it does not allow modes to respond in a correlated maimer to each other. This problem can be somewhat alleviated by a good definition of the relevant coordinate system [134. 136]. (An extension of mean-field methods that does allow for coupling [137. 138 and 139] will be discussed later.)... 

The original PCM method uses a cavity made of spherical regions around each atom. The isodensity PCM model (IPCM) uses a cavity that is defined by an isosurface of the electron density. This is defined iteratively by running SCF calculations with the cavity until a convergence is reached. The self-consistent isodensity PCM model (SCI-PCM) is similar to IPCM in theory, but different in implementation. SCI-PCM calculations embed the cavity calculation in the SCF procedure to account for coupling between the two parts of the calculation. 

RPA, and CPHF. Time-dependent Hartree-Fock (TDFIF) is the Flartree-Fock approximation for the time-dependent Schrodinger equation. CPFIF stands for coupled perturbed Flartree-Fock. The random-phase approximation (RPA) is also an equivalent formulation. There have also been time-dependent MCSCF formulations using the time-dependent gauge invariant approach (TDGI) that is equivalent to multiconfiguration RPA. All of the time-dependent methods go to the static calculation results in the v = 0 limit. 

Interestingly, 1,2-dichloroethylene can be used for coupling without activation of the chlorides. The reaction of c -1.2-dichloroethylene (331) has wide... 

Triflates are used for the reaction[470]. The 5-phenyltropone 609 is prepared by coupling of the triflate with phenylzinc chloride[471]. Instead of the expensive triflale, phenyl fluoroalkanesulfonate as a triflate equivalent is used for coupling[472]. Phenyl fluorosulfonate (610) is another reagent used for cou-pling[473]. 

Arenediazonium salts are also used for the couplina[563], (Z)-Stilbene was obtained unexpectedly by the reaction of the ti-stannylstyrene 694 by addition-elimination. This is a good preparative method for cu-stilbene[564]. The rather inactive aryl chloride 695 can be used for coupling with organostannanes by the coordination of Cr(CO)3 on aromatic rings[3.565]. 

For coupling, the cheaper aryl fluorosulfonate 713 is used as an alternative to the expensive aryl triflates to give the same results[473]. The arenesulfonates 714 are active for the reaction with vinylstannanes when dppp and LiCI are used in DMSO[583], The bromide 715 attacks the arylstannane moiety selectively without reacting with the organoboron moiety in 716 in the absence of a base[584]. 

Alkenylation of cyclopentenone with the alkenylstannane 719 has been used for the introduction of an a,>-chain into a prostaglandin derivative[590]. Even the vinyl mesylate (methanesulfonate) 720 can be used for coupling with alkenylstannanes[59l]. 

Tin enolates of ketones can be generated by the reaction of the enol acetate 733 with tributyltin methoxide[60i] and they react with alkenyl halides via transmetallation to give 734. This reaction offers a useful method for the introduction of an aryl or alkenyl group at the o-carbon of ketones[602]. Tin enolates are also generated by the reaction of siiyl enol ethers with tributyltin fluoride and used for coupling with halides[603]. 

Successive yields for coupling and cyclization or overall yield. 

We often see splitting patterns in which the intensities of the individual peaks do not match those given in Table 13 2 but are distorted in that the signals for coupled protons lean toward each other This leaning is a general phenomenon but is most easily illus trated for the case of two nonequivalent vicinal protons as shown m Figure 13 18... 

Step 2 The Boc protecting group is removed by treatment with hydrochloric acid m dilute acetic acid After the resin has been washed the C terminal ammo acid IS ready for coupling... 

In the previous section we saw how voltammetry can be used to determine the concentration of an analyte. Voltammetry also can be used to obtain additional information, including verifying electrochemical reversibility, determining the number of electrons transferred in a redox reaction, and determining equilibrium constants for coupled chemical reactions. Our discussion of these applications is limited to the use of voltammetric techniques that give limiting currents, although other voltammetric techniques also can be used to obtain the same information. 

Determining Equilibrium Constants for Coupled Chemical Reactions Another important application of voltammetry is the determination of equilibrium constants for solution reactions that are coupled to a redox reaction occurring at the electrode. The presence of the solution reaction affects the ease of electron transfer, shifting the potential to more negative or more positive potentials. Consider, for example, the reduction of O to R... 

Eig. 5. Schematic diagrams of small emission area LED chip stmctures. (a) Cross section of a surface-emitting LED which typically possesses a 20—60 )Tm diameter emission area for coupling to optical fibers, (b) An edge-emitting device which generally possesses a smaller (3—5 )Tm) emission width and is... 

Ceramic, Metal, and Liquid Membranes. The discussion so far implies that membrane materials are organic polymers and, in fact, the vast majority of membranes used commercially are polymer based. However, interest in membranes formed from less conventional materials has increased. Ceramic membranes, a special class of microporous membranes, are being used in ultrafHtration and microfiltration appHcations, for which solvent resistance and thermal stabHity are required. Dense metal membranes, particularly palladium membranes, are being considered for the separation of hydrogen from gas mixtures, and supported or emulsified Hquid films are being developed for coupled and facHitated transport processes. 

Hydroxynaphthalenesulfonic acids are important as intermediates either for coupling components for a2o dyes or a2o components, as well as for synthetic tanning agents. Hydroxynaphthalenesulfonic acids can be manufactured either by sulfonation of naphthols or hydroxynaphthalenesulfonic acids, by acid hydrolysis of arninonaphthalenesulfonic acids, by fusion of sodium naphthalenepolysulfonates with sodium hydroxide, or by desulfonation or rearrangement of hydroxynaphthalenesulfonic acids (Table 6). 

Phosphorothioates. All three synthetic approaches appHcable to unmodified oligonucleotides can be adapted for synthesis of phosphorothioates (11) (33,46). If all of the phosphodiester linkages in an oligonucleotide are to be replaced with phosphorothioates, the ff-phosphonate method for coupling, followed by oxidation with Sg in carbon disulfide and triethylamine in the final step, is the most straightforward method. 

---