Proton glass samples

Figure 1. Proton relaxation times vs. 10 /T of adsorbed water in porous glass samples 2 and 5 at (a) P/Po = 0.88 and (b) P/Po = 1.00 (—) indicates the experimental trends.

Figure 4. Proton spectra obtained by (a p) reactions on glass samples (1)...

Proton spectrum of a thin glass sample having high boron content irradiated by a 4 MeV a-particle beam (Peisach and Pretorius 1973)... 

It has been reported that exchange of protons activated by enolization can be performed directly in a glass inlet system of the mass spectrometer prior to analysis by heating the sample at about 200° with deuterium oxide vapor for a few minutes. " Exchange has been observed with 2-, 3-, 6-, 11- and 17-keto steroids, but the resulting isotopic purity is usually poor,... 

The sensor is an ammonium ion-selective electrode surrounded by a gel impregnated with the enzyme mease (Figme 6-11) (22). The generated ammonium ions are detected after 30-60 s to reach a steady-state potential. Alternately, the changes in the proton concentration can be probed with glass pH or other pH-sensitive electrodes. As expected for potentiometric probes, the potential is a linear function of the logarithm of the urea concentration in the sample solution. 

The area below the absorption curve is proportional to the number of protons in the sample which permits the decrease of free plasticizer to be calculated from the change of this area upon cooling. For each sample the area below the curve is constant, regardless of whether the absorption is narrow or broad. Below the glass temperature the narrow component of the absorption curve can be attributed to the plasticizer, whereas the broad component represents the glassy polymer and that part of the plasticizer which is already immobilized. 

With a magnetic field of H0 = 11.75 T and a 500-MHz oscillator, the positions of proton resonances in organic compounds are spread over a range of -10,000 Hz. This is 20 parts per million (ppm) relative to 500 MHz. Positions of individual resonances are usually given in ppm and are always measured in terms of a shift from the resonance position of some standard substance. For protons this is most often tetramethyl-silane (TMS), an inert substance that can be added directly to the sample in its glass tube. Biochemists... 

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