Hysterisis

The excitation current was fixed for the realized probe at 1mA. The computed field resulting for this current value is lower than 100 Am, in order to be located in the linear zone of the hysterisis diagram (Rayleigh). Whatever the type of the chosen probe or the excitation frequency, the same zone is controlled. The surface of this zone is 100 mm (10x10). 

Nitrogen adsorption/desorption isotherms on Zeolite and V-Mo-zeolite are very similar and close to a type I characteristic of microporous materials, although the V-Mo-catalysts show small hysterisis loop at higher partial pressures, which reveals some intergranular mesoporosity. Table 1 shows that BET surface area, microporous and porous volumes, decrease after the introduction of Molybdenum and vanadium in zeolite indicating a textural alteration probably because of pore blocking by vanadium or molybdenum species either dispersed in the channels or deposited at the outer surface of the zeolite. The effect is far less important for the catalysts issued from ZSM-5. 

Lotus effect surfaces, 22 108-127 adhesion of dust on, 22 115-116 contact angle hysterisis and, 22 113-114 development of, 22 117-120 problems and outlook for, 22 123-124 properties and applications of materials with, 22 121-124 roughness and, 22 110-113 water repellancy of, 22 108-109, 109-110, 112 Lovastatin, 5 142... 

The Effect of Illumination. In an alkaline solution, an n-GaP electrode, (111) surface, under illumination shows an anodic photocurrent, accompanied by quantitative dissolution of the electrode. The current-potential curve shows considerable hysterisis as seen in Fig. 2 the anodic current, scanned backward, (toward less positive potential) begins to decrease at a potential much more positive than the onset potential of the anodic current for the forward scanning, the latter being slightly more positive than the Ug value in the dark, Us(dark). 

A typical CC-measurement procedure (for a pH-sensitive LAPS structure) is depicted in Fig. 6.3. From the raw data material of the CC-mode measurement of all measurement spots under the pH-sensitive layer, a calibration plot can be derived. For example, for the above example, an average pH sensitivity of 54.2 mV/pH with a standard deviation of 0.5 mV/pH between the different measurement spots can be calculated. This initial calibration measurement allows furthermore the determination of different measurement parameters, e.g., the hysterisis, overall drift, stability, selectivity and the influence of external disturbances such as light and temperature. These parameters are important to evaluate the performance of the complete LAPS-based measurement system. 

Effect of H2O on K-Vaporization Similar TMS experiments were performed but with H2O as the added reactant and a non-reducing atmosphere. An unexpected K-pressure dependence on H2O was found, as shown in Figure 19. No hysterisis effects were observed in this case. A similar, though less pronounced (factor of four less effect on K-pressure), H20-induced K vaporization effect was noted in the more acidic and more viscous MHD (K ) slag sample (65). 

Let us consider, for example, the simple nernstian reduction reaction in Eq. (221) and a solution containing initially only the reactant R. Before any electrochemical perturbation the electrode rest potential Ej is made largely positive to E . At time zero the potential is stepped to a value E2, sufficiently negative to E , so that the concentration of R is close to zero at the electrode surface. After a time 6, the electrode potential is stepped back to El, so that the concentration of P at the electrode surface becomes zero. When this potentiostatic perturbation, represented in Fig. 21a, is applied in a steady-state method, the R and P concentration profiles are linear and depend only on the electrode potential but not on time, as shown in Fig. 20a (for k 0). Yet when the same perturbation is applied in transient methods, the concentration profiles are curved and time dependent, as evidenced in Fig. 21b. Thus it is seen from this figure that a step duration at Ei, much longer than the step duration 0 at E2, is needed for the initial concentration profiles to be restored. This hysterisis corresponds to the propagation of the diffusion perturbation within the solution, which then keeps a memory of the past perturbation. This information is stored via the structuring of the concentrations in the space near the electrode as a function of the elapsed time. 

Nitrogen absorption isotherms and the hysterisis loops are affected by the nature of A1 distribution in ZSM-5, with shape of the loop being more symmetrical and larger for a more uniform distribution (11). The shape selectivity of ZSM-5 catalysts (12) and the hydrophobicity (13, 14) are dependent on the zoning of A1 in the crystals. 

Low temperature N2 adsorption isotherm gives a reliable information on the mesoporous texture of solids. The adsorption-desorption plot follow the type IV isotherm with hysterisis in the mesopore filling region, the pore size distribution obtained by BJH analysis of nitrogen adsorbed is shown in Fig.3. The pore size distribution is narrow and the maximum is centered around 30 A for all the samples indicating a uniform pore texture of the samples... 

FA Hessari, SK Bhatia. Reaction rate hysterisis in a single partially internally wetted catalyst pellet Experiment and modelling. Chem Eng Sci 51 1241-1256,1996. 

Figure 6.2 CSTR hysterisis in the liquid-phase reaction between sodium thiosulfate and hydrogen peroxide. [After S.A. Vejtassa and R.A. Schmitz, Amer. Inst. Chem. Eng. J., 16,410, with permission of the American Institute of Chemical Engineers.]...

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