Generation of protons

Does Ae generation of protonic acid sites originating from molecular hydrogen occur for the catal ts other than Pt/S042--ZrO2 ... 

W Gevers. (1977). Generation of protons by metabolic processes in heart cells. J Mol Cardiol 9 867-874. 

Rottenberg, H. (1998) The generation of proton electrochemical potential gradient by cytochrome c oxidase. Biochim. Biophys. Acta 1364, 1-16. 

The present synthesis is an adaptation of a previously reported synthesis4 in a divided cell (i.e., separate anode and cathode compartments). The overriding consideration in making this modification has been to simplify the operations involved and render the synthesis more attractive to chemists not well acquainted with electrochemical procedures. The main simplification achieved is that the pH is controlled internally via the anodic generation of protons as noted above (in the reported procedure4 this is achieved by periodic addition of acetic acid to the cathode compartment). A further simplification has been to run the reaction with a constant current rather than at controlled cathode potential. After the electrolysis has been initiated, the reaction requires no special attention. A small price is paid for the simplicity of the present synthesis in that the yield is somewhat lower than that obtained previously.4 The major by-product formed is diethyl succinate, which results from a 2e reduction of diethyl fumarate or diethyl maleate ... 

The kinetics of pH are governed by proton binding and unbinding as well as the consumption and generation of protons via chemical reactions. For a general system of Nr reactants, and considering [H+], [Mg2+], and [K+] binding, the total... 

As a control to check that established CID thresholds could be reproduced with the ESMS setup, the thresholds for the reaction [(H20)n(H30)]+— [(H20)n 1(H30)]++H20, which had been determined earlier by Armentrout et al. [139] and Kebarle et al. [140], were measured. Generation of protonated water clusters is particularly simple by electrospray of a 10 4 mol I1 aqueous HCl solution (Fig. 9a). Thresholds were measured at four different, decreasing pressures and extrapolated to zero pressure in order to eliminate the contribution of multiple collisions to the foot of the threshold curve. The threshold for n=l, measured in daughter-ion mode, was extracted from our data with Armentroufs CRUNCH program, yielding a value of 1.29 eV (see Fig. 9b) [81], in excellent agreement with the published data. 

As an alternative for the external application of a stepwise change in pH, as described above, titrant can be added by coulometry. Coulometric generation of protons or hydroxyl ions is possible by sending a current between a noble metal actuator electrode, situated closely around the ISFET gate, and a distant counter electrode 115]. 

The slope of the measured titration curve is inversely proportional to the buffer capacity of the protein, which contains specific information on the type of protein. After modification of the coulometric sensor-actuator device with a porous gold actuator electrode, the device is shown to be suitable for the determination of protein buffer capacity in solution [17]. A schematic representation of the device is shown in Fig. 12. The buffer capacity can be measured by sending a small alternating current through the porous actuator electrode, resulting in the alternating generation of protons and hydroxyl ions. This will result in a small pH perturbation in the free space of the porous electrode, which is detected by... 

Other accelerator-produced radionuclides are also used in nuclear medicine (Table 19.2). One of the most important radionuclides in this group is This radioisotope of iodine has more favourable properties than it emits only y radiation and its relatively short half-life is more appropriate for medical application. Its production is described in section 12.1. Suitable accelerators for the generation of protons of relatively high energy, and transport facilities, are needed. 

Organisms have evolved a number of elaborate mechanisms for the generation of proton gradients across membranes. 

In Fig. 6 an example is given for the crosslinking of VEi using the DPA/I(i) initiator system. The linearity of the plot demonstrates that Eq. 9 is fully obeyed. Moreover, it is possible to determine the h- t-value by dividing and inverting the slope of the plot by the intercept The values obtained (90) used the same order as the value determined using the sensitizer photolysis in DME/HMDS mixture (100). These kinetics directly reflects the generation of protons. 

The inhibition time reflects the generation of protons in the system used, see Eq. 5. Usually in cationic crosslinking oxygen has no irtfluence on the crosslinking kinetics Nevertheless, our results show that the inhibition time was influenced by the air pressure (Fig. 7). Moreover, this influence is stronger at higher... 

For exploring SECM features of the electrochemical robotic system, two electrodes were controlled by the robotic system to electrochemically deposit spots of an anodic electrodeposition paint82 on a surface. The deposition of the negatively charged polymer is realized by anodic water oxidation under generating of protons. The process is schematically illustrated in Fig. 14.28. The pH shift in the vicinity... 

Chemical ionization Generation of protonated See EI fragmentation less pronounced... 

Fig. 18. The reversible generation of protons, (a) Pd(II)/HTP, (b) Pd /HTP in the presence of hydrogen (13.3 kPa), (c) Pd /HTP evacuated at 423K for 1 h. (d) llie sample (c) re-exposed to hydrogen (13.3 kPa) at 423K for 30 min. Hie spectra measured at 298K. The resonance frequency was 300 MHz. ( ) denotes a spinning sideband. Tbe molar ratio of Pd/HTP was 1.5.

Elsewhere (22) a model for the highly acidic sites is discussed that is supported by electrostatic potential calculations. According to that model the activity is due to generation of protons coordinated to oxygen ions that connect the silicon-containing tetrahedra with aluminium-containing octrahedra. Such sites, however, can only contribute to catalysis at lateral planes, at lattice dislocations in the basal plane or at the edges of the lateral and basal planes. 

Figure 31 The generation of final products H+ and Cl during the photodegradation of 0.028 mmol/L DR in Tween 80 surfactant solutions at 253.7 nm. The HPLC analysis and UWVisible spectrometric analysis (color) of the DR is also compared. Photodecolouration occurred with a time delay after the photodechlorination. Generation of proton concentration and chloride concentration is 1 1 stoichiometricly matched.

Fig. 9.13 Scheme for the generation of protons via photoinduced electron transfer (PET). 

The high catalytic activity of CuY and CuY(R) is due to conversion of Lewis sites to Broensted sites during activation of CuY and due to generation of protons during reduction of Cu by hydrogen respectively. The relatively low activity of NaY is due to very low Broensted acidity. High activity of HY is due to very large value of Broensted acidity. 

Electron transport from NADH and FADH2 to oxygen generation of proton-motive force... 

We now report results of a study of the thermal decomposition patterns in the 4 methyl-substituted ammonium (MA) exchanged Y-type faujasites, detailed transformation of the TTMA form, and the resulting generation of protonic acidity. 

Organisms have evolved a number of elaborate mechanisms for the generation of proton gradients across membranes. An example is photosynthesis, a process first used by bacteria and now also used by plants to harness the light energy from the sun. The essence of photosynthesis is the light-driven transfer of an electron across a membrane. The fundamental processes are illustrated in Figure 2.18. 

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