TAP study

Goguet, A., Shekhtman, S.O., Burch, R., Hardacre, C., Meunier, F.C., and Yablonsky, G.S. 2006. Pulse-response TAP studies of the reverse water-gas shift reaction over a Pt/Ce02 catalyst../. Catal. 237 102-10. 

The stiff regions observed in the studies of McLean et al. were assigned to fluorocarbon crystalline domains, the size of which was around 10 nm. The crystalline packing was referred to as lamellae which are not organized into stacks, as is the case for the Surlyn ionomers that were studied. An interesting outcome of the normal tapping studies was the discovery of a very thin ( 5 A) fluorine-rich layer over the surface in which the contrasted soft regions are amorphous. 

Other research [65, 67, 202] has shown that butene oxidation can produce many selective products (furan, acetaldehyde and methyl vinyl ketone) which are not detected during butane oxidation. It cannot be assumed that the oxidation of butane and the unsaturated reactants proceed along the same pathway. The kinetic data must be viewed with this in mind, although butane activation is widely accepted to be the rate determining step. The intermediates are capable of desorbing from the surface, (as seen in the TAP studies) but do not do so, indicating that the further reactions occur more readily than desorphon. 

The mechanism was based on kinetic data calculated for the oxidation of butane, 1-butene, 1, 3-butadiene and furan over (VO)2P207 and VOPO4 phases. Unlike TAP studies, the kinetic data suggested that furan is not an intermediate for butane oxidation, but is an intermediate for butadiene oxidation. The differences observed in the oxidation of butane and the unsaturated hydrocarbons questions the validity of applying butene and butadiene oxidation results to the butane system. 

Treatment of Age-related Macular Degeneration with Photodynamic Therapy (TAP) Study Group. Photodynamic therapy of subfoveal choroidal neovascularization in age-related macmar degeneration with verteporfin. Arch Ophthalmol 1999 117 1329-1345. 

A subsequent trial, the Verteporfin in Photodynamic Therapy (VIP), used the same treatment and follow-up protocol as did the TAP study, but it evaluated AMD in subjects with CNVM that was either occult only (with evidence of recent progression or hemorrhage) or... 

Side effects of verteporfin therapy have been extensively studied. The TAP study provided the largest amount of data on adverse effects, which included the following incidences in treated versus control patients visual disturbance (abnormal or decreased vision) in 22.1% versus 15.5%, injection-site adverse events in 15.9% versus 5. 8%, photosensitivity reactions in 3 5% versus 0%, back pain in 2.5% versus 0%, and allergy reactions in 2.0% versus 3.9%. Further data on adverse events were provided by the VIP study, determining that many of the resulting adverse events were similar in incidence to those reported in the TAP study but fewer photosensitivity or injection site reactions were observed. This latter difference was attributed to better compliance with overall protocols of the study design. 

The results of Nibbelke et al. 11) were confirmed by a later TAP study by Malleus et al 146). 

A TAP study of the reaction over 1% Rh/AFOs at 740°C (76.7) gives results similar to those discussed previously (767). Only normalized responses are shown. The role of water is important, and a companion in... 

The activity of supported noble metals for the reduction of by h) drocarbons in the presence of oxygen has been studied (233). It has been shown by TAP studies that C3H6/O2 is a more effective reductant of NO than H2 or CO alone (234, 235). 

The kinetics of NOx reduction were found to be very similar to those of C3H6 oxidation both reactions are 1.8 order in O2, zero order in C3H6 and inhibited by NO (Fig. 1-5). This is consistent with NOx reduction occurring via the dissociation of molecularly adsorbed NO on vacant Pt sites, followed by the formation of N2 and N2O by the combination of adsorbed N and NO. This mechanism is supported by our earlier TAP study [6]. It is also in agreement with the observation that the ratio of N2 N2O formed is independent of contact time (Fig. 2) indicating that N2 and N2O are formed from parallel routes. This can be represented as ... 

The efficacy of verteporfin PDT in reducing the risk of vision loss in patients with subfoveal CNV due to AMD was investigated in multicenter, double-masked, placebo-controlled, randomized trials. The Treatment of Age-Related Macular Degeneration with Photodynamic Therapy (TAP) study consisted of two identically designed trials conducted in 22 ophthalmology practices in Europe and North America and evaluated PDT for new and recurrent subfoveal CNV with some classic component (8-11). The Verteporfin in Photodynamic Therapy (VIP) study was carried out in 28 practices across Europe and North America and involved patients with only occult CNV or classic CNV with good visual acuity as well as a subset with CNV caused by pathologic myopia (12-14). 

A total of 609 patients were enrolled in the TAP study between December 1996 and October 1997 and randomly assigned to verteporfin therapy (402) or placebo (207). Ninety-four percent of patients in each group completed the 12-month follow-up examination while 87% of the verteporfin group and 86% of the placebo group completed the 24-month follow-up. 

Figure 1 TAP study. Kaplan-Meier estimate of the cumulative proportion of eyes with moderate vision loss (>15 letters) in verteporfin-treated and placebo groups at each three-month study visit. Abbreviation TAP, Treatment of Age-Related Macular Degeneration with Photodynamic Therapy. Source From Ref. 9.

Photodynamic therapy with verteporfin through 24 months of follow-up and treatment in both the TAP and VIP studies appeared quite safe. The treatment was well tolerated with minimal adverse events attributable to treatment. Photosensitivity reactions were rare and lower in incidence in the VIP study (1%) than the TAP study (3%) despite the shorter recommended protection period of 24 hours compared with 48 hours. Allergic reactions were also rare and more frequent in the placebo groups. The only other nonocular adverse event related to treatment was lower back pain during verteporfin infusion, which occurred in a total of 15 people across both studies. 

Some visual disturbance following treatment was common in both verteporfin-treated and placebo eyes. However, the incidence of severe decrease in vision, defined as a loss of 20 letters (four lines) or more within seven days of treatment was low. The risk appeared to be higher in eyes with occult but no classic CNV, occurring in 10 (4.4%) patients in the VIP study compared with three (0.75%) in the TAP study. 

Of the cases in the VIP trial, the visual loss was attributed to the development of extensive subretinal fluid with choroidal hypofluorescence in one case and sub-retinal pigment epithelial hemorrhage in three cases. No obvious cause was detected in six cases. Vision recovered to < 20 letters lost in five of the 10 patients at three months after the events. Although preclinical studies demonstrated some damage to the RPE with PDT, the Phase III data did not suggest any increase in RPE atrophy in verte-porfin-treated patients. For both groups in the TAP study, the distribution of lesion sizes with the inclusion of surrounding atrophy did not differ from the distribution of lesion sizes without atrophy. 

For two other methods often used for the characterization of zeolitic materials, parallelized implementations have been described in the literature, i.e. TAP studies and TPD experiments. Also these experiments, as is the case for IR measurements with probe molecules, need a long time for sample loading, pumping, pre-treatment and conditioning steps, while the actual experiment is relatively short. These experiments can therefore... 

The NO-decomposition / oxygen clean-off mechanism was introduced by Burch et. al. [2] NO adsorbs on vacant Pt-sites, and dissociates, generating Pt-0 species and Pt-N species. Pt-N recombines with NO, to form NzO, or with another Pt-N, to form Nz. The hydrocarbon (e.g. propene), reacts with the Pt-0 species, yielding COz. In a recent TAP-study on Pt-ZSM-5 [4] this mechanism was more or less confirmed, and evidence presented for a correlation between NzO-selectivity and oxygen coverage. 

The third basic principle of TAP, that of uniformity of the surface composition across the active zone, proposed by Shekhtman et al. (1999), has to be considered an absolute necessity in TAP studies because kinetic information corresponding to a certain catalyst composition cannot be obtained directly if nonuniform catalyst states are probed. 

In this chapter, the problem of optimization of multizone configurations will be dealt with. When talking about a zone, we consider a thin active zone in which perfect mixing is assumed. Typically, thin catalyst zones are used in temporal analysis of products (TAP) studies, but other types of experiments involving thin active zones are also conceivable. 

Li ZL. TAP Studies for Ammonia S5nithesis and Dissociation on Carbon Nano Fiber Supported Catalysts, Disseratation, DaUan DaUan Institute of Chemical Physics, Chinese Academy of Sciences, 2004. 

Shekhtman, S., Goguet, A., Burch, R., et al. (2008). CO multipulse TAP studies of 2% Pt/Ce02 catalyst Influence of catalyst pretreatment and temperature on the number of active sites observed, J. Catal, 253, pp. 303-311. 

TAP Study Group, Treatment of age related macular degeneration with photodynamic therapy (TAP), photodynamic therapy of subfoveal choroidal neovascularization in age related macular degeneration with verteporfin one year results of two randomized clinical trials - TAP report 1, Arch. Ophthalmol, 117, 1329, 1999. 

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