Petra

The formulation for Impet from Ticona (a Division of the Hoechst Celanese Corporation) is described in United States Patent 6020414 [43]. The latter discloses toughened PET formulations based on an ethylene-alkyl acrylate copolymer and an ethylene-alkyl methacrylate copolymer. The crux of this patent is to use a combination of an elastomeric terpolymer functionalized with glycidyl acrylate or glycidyl metliacrylate and an alkyl acrylate or alkyl methacrylate (tlie latter forming the major part of the combination - up to 40 wt%). For instance. 

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Any one of these additivity schemes can be used for the estimation of a variety of thermochemical molecular data, most prominently for heats of formation, with high accuracy [13]. A variety of compilations of thermochemical data are available [14-16]. A computer program based on Allen s scheme has been developed [17, 18] and is included in the PETRA package of programs [19]. 

A range of physicochemical properties such as partial atomic charges [9] or measures of the polarizabihty [10] can be calculated, for example with the program package PETRA [11]. The topological autocorrelation vector is invariant with respect to translation, rotation, and the conformer of the molecule considered. An alignment of molecules is not necessary for the calculation of their autocorrelation vectors. 

The chirality code of a molecule is based on atomic properties and on the 3D structure. Examples of atomic properties arc partial atomic charges and polarizabilities, which are easily accessible by fast empirical methods contained in the PETRA package. Other atomic properties, calculated by other methods, can in principle be used. It is convenient, however, if the chosen atomic property discriminates as much as possible between non-equivalent atoms. 3D molecular structures are easily generated by the GORINA software package (see Section 2.13), but other sources of 3D structures can be used as well. 

PETRA (calculation of physicochemical parameters) Molecular Networks GmbH, Nagelsbachstrasse 25, D-91052 Erlangen, Germany http //www.mol-net.de/ VolSurf Molecular Discovery Ltd., West Way House, Elms Parade, Oxford 0X2 9LL, UK http //www.moldiscovery.com/... 

PETRA Version 3 is available from Molecular Networks GmbH, Nagelsbachstr. 25, 91052 Erlangen, Germany (http //www.mol-nct.de) and can be tested via the Internet at http // www2.chemie.uni-eriangen.de/ sojiware/petra... 

Thus, a list of 1 5 descriptors was calculated for these purposes, as described below. The partition coefficient log P (calculated by a method based on the Gho.sc/Crip-pen approach [11]) (see also Chapter X, Section 1.1 in the Handbook) was calculated because it affects the solubility dramatically [17, 18]. All the other descriptors were calculated with the program PETRA (Parameter Estimation for the Treatment of Reactivity Applications) [28. ... 

Using the results from PETRA and GORINA, the required descriptors are calculated for all the protons adjacent to C atoms. 

This coding is performed in three steps (cf Chapter 8) First the 3D coordinates of the atoms arc calculated using the structure generator CORINA (COoRdlNAtes). Subsequently the program PETRA (Parameter Estimation for the Treatment of Reactivity Applications) is applied for calculating physicochemical properties such as charge distribution and polarizability. The 3D information and the physicochemical atomic properties are then used to code the molecule. 

This reaction data set of 626 reactions was used as a training data set to produce a knowledge base. Before this data set is used as input to a neural Kohonen network, each reaction must be coded in the form of a vector characterizing the reaction event. Six physicochemical effects were calculated for each of five bonds at the reaction center of the starting materials by the PETRA (see Section 7.1.4) program system. As shown in Figure 10,3-3 with an example, the physicochemical effects of the two regioisomeric products arc different. 

Physticochemical coiiatrainla Further constraints can be imposed on the atoms and bonds of the reaction center, such as those physicochemical factors calculated by the PETRA package (see Section 7.1). For example, the partial charges calculated by the PEOE method can be used to extract the chemically feasible reaction from the two conceivable ones as illustrated in Figure 10.3-11. 

The word petroleum is de rived from the Latin words for rock (petra) and oil (oleum)... 

The present North American market is dominated by Du Pont, no doubt by virtue of their early lead other suppHers are AlliedSignal with Petra and Hoechst Celanese Corporation with Impet. Eastman also markets PET injection mol ding grades under the trade name Thermx. In Europe the situation... 

PET industrial synthesis, 70 PET monomers, recycling of, 539-541 PET products, recycled and depolymerized, 531-532 PETRA, 532... 

Petra van Koppen, University of California, Santa Barbara... 

We thank Petra Lembke and Petra Heese for assistance during the cell wall analysis. We thank Dr. U. Sonnewald for the generous gift of the transgenic invertase plants. This work was supported by a DFG grant to SHB (HO 1605/1-2). 

In 2001, a screening study for the enantioselective reduction of various aryl ketones was developed by Petra et al. in the presence of amino sulfide... 

In summary, the NLE technique offers a concepmally new approach to observe NFS. Existing limits for time resolution could be overcome by a microfocused synchrotron beam (as planned for PETRA III) and by detectors with high spatial resolution and background from SAXS could be suppressed by employing high-energy transitions and crystalline sapphire as rotor material. 

Dixon, Laurinda S. and Petra ten-Doesschate Chu. An iconographical riddle Gerbrandt van den Eeckhout s "Royal repast" in the Liechtenstein Princely Collections. Art Bulletin 71 (1989) 611-627. 

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