Resolution experimental procedures

Based on the ACR "virtual" catalytic tests and optimization can be performed using HRS (further details are given in the experimental part). Alternatively the whole experimental space can be mapped (see Fig. 1). After subsequent verification step a high resolution experimental space is created and further optimization takes place by HRS creating 1-3 more catalyst generations. After the last verification procedure the... 

Reason for the effective optical resolution by the inclusion complexation with a chiral host has been clarified by X-ray analysis of the complex formed. By the X-ray structural study of the host-guest complex, absolute configuration of the chiral guest resolved has also been elucidated easily, since absolute configuration of the chiral host is known. These X-ray data have been reported in the literature cited together with the detailed experimental procedure of the resolution. 

To evolve useful enzymes, genetic engineering technology has been applied increasingly to improve stability of enzymes, enantioselectivity, extension of substrate specificity for kinetic resolution of racemic compounds. Novel enzymes created by this technique will be available in large quantities and varieties within a next few years. In the near future, a lot of useful enzymes will be on the market and expanding number of chemists can use enzymes more freely than present due to the improvement in the simplification of experimental procedures. 

Methods of resolution seldom possess the scope and generality of application associated with purely synthetic processes. The worker in this field therefore is obliged to place more than the usual reliance upon knowledge of underlying principles and upon patient and resourceful experimentation guided by extensive acquaintance with the literature. For this reason, a brief statement of the underlying principles and the main steps in the experimental procedure for all the important methods of resolution are included. ... 

Figure 4. Section of the pseudobinary phase diagram of the sulfuric acid SLP catalytic material. The data were taken from Ref. 16. The data points were derived from anomalies of the conductivity versus temperature curves of the respective mixtures. At the high compositional resolution and in the range of the global eutectic, the formation of a vanadate-sulfato complex causes the local maximum in the solidus curve. It is noted that extreme precision in the experimental procedures was necessary to derive this result illustrating the characteristic of fused systems that compound formation can well occur in the molten state.

FTIR spectra of the self-supported zeolite discs were collected at a resolution of 2 cm 1 using a Nicolet Magna 550 FTIR spectrometer. Pyridine was used as a probe molecule to characterise Broensted and Lewis acid sites. Prior to all FTIR experiments the samples were activated under vacuum at 400°C for 16 h. The detailed experimental procedure is described elsewhere.12 The IR spectra of the reduced samples were collected at ambient temperature after reduction of the catalysts by hydrogen at 500°C (Ph2 = 50 torr, duration of treatment = 1 h). 

The operational characteristics such as depth resolution, maximum accessible depth and minimum detection limit in ERD are highly subjective to each experiment condition. In our system with the conditions described in the experimental procedures section and assuming Si as the primary matrix for the target, the typical performance characteristics in routine applications are 80-100 A depth resolution, 1 pm maximum depth and about 0.1 at.% minimum detection limit. For more discussion of operation characteristics one may refer to our earlier work (2). 

The empirical approach adopted here integrates classical electrochemical methods with modem surface preparation and characterization techniques. As described in detail elsewhere, the actual experimental procedure involves surface analysis before and after a particular electrochemical process the latter may vary from simple inunersion of the electrode at a fixed potential to timed excursions between extreme oxidative and reductive potentials. Meticulous emphasis is placed on the synthesis of pre-selected surface alloys and the interrogation of such surfaces to monitor any electrochemistry-induced changes. The advantages in the use of electrons as surface probes such as in X-ray photoelectron spectroscopy (XPS), Auger electron spectroscopy (AES), high-resolution... 

Ferrocene behaves like an aromatic compound activated for electrophilic substitution reactions. Thus, only minor modifications of experimental procedures developed for aromatics are necessary to obtain ferrocene derivatives (a useful review on general methods is given by Schldgl and Falk [42]). For central chiral ferrocenes, resolution of the racemate is a frequently applied technique. Traditionally, resolutions are best achieved by salt formation between a chiral acid or base and the... 

Several studies involving FFF channel modifications and new experimental procedures have been aimed at increasing detectability. For example, frit-outlet flow FFF utilizes a section of the frit depletion wall near the channel outlet to remove sample-free carrier and, thus, concentrate the separated sample just prior to its reaching the detector. A 10-fold increase in the detector response of purified proteins was achieved without any effect on retention time or resolution [8]. Frit-inlet flow FFF involves a... 

Detailed experimental procedures for obtaining infrared spectra on humic and fulvic acids have been reported previously 9,22,25-26) and will be briefly described here. Infrared spectra were taken on the size-fractionated samples by using a Fourier transform infrared spectrometer (Mattson, Polaris) with a cooled Hg/Cd/Te detector. Dried humic and fulvic materials were studied by diffuse reflectance infrared spectroscopy (Spectra Tech DRIFT accessory) and reported in K-M units, as well as by transmission absorbance in a KBr pellet. Infrared absorption spectra were obtained directly on the aqueous size-fractioned concentrates with CIR (Spectra Tech CIRCLE accessory). Raman spectra were taken by using an argon ion laser (Spectra-Physics Model 2025-05), a triple-grating monochromator (Spex Triplemate Model 1877), and a photodiode array detector system (Princeton Applied Research Model 1420). All Raman and infrared spectra were taken at 2 cm resolution. 

A few years later, by using the same experimental procedures, the same scientists prepared cyclic polybutadienes170 (Scheme 82). THF was the polymerization solvent, which results in a 60% 1,2-content. From the g values was concluded that some of the cyclic polybutadienes (PBd) were contamined by their linear precursors. A high-resolution column set was used in order to separate the linear from the cyclic polymer. In this work the characterization analysis was the most comprehensive presented so far. Recently, these cyclic PSs were analyzed by high-pressure liquid chromatography under critical conditions, which is a method that can separate linear and cyclic macromolecules according to their archi-... 

For softer, rubbery polymers, a different experimental procedure gives better results. For these experiments we have measured directly the penetration distance of a tiny weighted probe into the cross-sectioned surface of polymer samples. For this purpose we have made use of a Perkin-Elmer Thermomechanical Analyzer equipped with a tip modified to be small enough to provide measurements of the desired resolution. (We are currently using a conical diamond phonograph needle having a tip angle of 60°.)... 

Photochemically generated acid must diffuse in resist film to catalyze desired reactions and to provide a gain mechanism for amplification. However, excessive diffusion (into the unexposed areas) destroys the linewidth control and eventually the resolution. Thus, as the minimum feature size becomes smaller and smaller, the control of acid diffusion plays a more important and difficult role. Therefore, investigation of acid diffusion in chemical amplification resist film is one of the most active areas of research today. A number of experimental procedures to measure acid diffusion length have been reported [67-88] ... 

One of the more important current applications of high-resolution multinuclear NMR is in the determination of the three-dimensional structures of proteins and other macromolecules in solution. These techniques are complementary to crystallographic methods. A typical experimental procedure is described in Box 2.2. 

An experimental procedure for the direct measurement of self diffusion is the radiotracer technique. Here, molecules are marked with radioactive atoms, e.g. with C, and deposited onto the surface of the crystal at a time t = 0. Thereafter, layers are sUced off the crystal surface sequentially at times t > 0 using a microtome. A typical layer thickness is 5 /rm. The crystal is thus dissected layer by layer and the quantity of tracer molecules in each layer is analysed with a spatial resolution given by the layer thicknesses [31, 32]. 

Another possible advantage of this experimental procedure is that during the delay most of the neutral species created during desorphon are allowed to dissipate and are pumped away so that ion-neuhal collisions are minimized. With this technique it is possible to achieve mass resolution of up to 10000, i.e., unit mass resoluhon can be obtained up to 7000 Da. ... 

Rosa, J.J., Richards, F.M. (1979) An experimental procedure for increasing the stmctural resolution of chemical hydrogen-exchange measurements on proteins Application to ribonuclease S peptide. Journal of Molecular Biology, 133 (3), 399- 16. 

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