Direct Methods of Investigation

Photoelectron spectroscopy is the most direct method of investigating electroiuc structure. The orbital structure of a molecule is reflected in the band structure of a PE spectrum. Detailed assigmnent of a spectrum is facilitated by varying the photon energy used for spectral acquisition. Effects of chemical substitution on molecular energetics can be probed... 

Measuring the d.c. conductivity of isolated metal particles, of course, is arguably the most direct method of investigating the size-induced metal-insulator transition within a single particle. Marquardt, Nimtz and coworkers believe they have succeeded in measuring the quasi-A.c. conductivity of individual indium nanoparticles... 

Among the main theoretical methods of investigation of the dynamic properties of macromolecules are molecular dynamics (MD) simulations and harmonic analysis. MD simulation is a technique in which the classical equation of motion for all atoms of a molecule is integrated over a finite period of time. Harmonic analysis is a direct way of analyzing vibrational motions. Harmonicity of the potential function is a basic assumption in the normal mode approximation used in harmonic analysis. This is known to be inadequate in the case of biological macromolecules, such as proteins, because anharmonic effects, which MD has shown to be important in protein motion, are neglected [1, 2, 3]. 

In extending this direct method of synthesis, we next investigated the possibility of preparing similarly constituted halides from 2-deoxy-D-arabino-hexose (2-deoxy-D-glucose) (21). The hexose was subjected to a partial anomerization procedure described by Bergmann and co-workers (1). The solid material obtained by this procedure is a mixture of the anomeric forms of 2-deoxy-D-arabino-hexose low temperature p-nitro-benzoylation of the latter in pyridine resulted in a mixture of crystalline, anomeric tetrakis-p-nitrobenzoates in a ratio of approximately 1 1. They were readily separable by fractional recrystallization, and treatment of either with an excess of hydrogen bromide in dichloromethane, or with... 

The rather strong relationship between meat use and fatal diabetes was only recently discovered, and to our knowledge this relationship has not been reported by other investigators. Since most people with diabetes do not die from their disease, mortality data is not the preferable type of data to use in investigating a possible causative link between diabetes and meat use. However, the relationship is fairly strong and shows a dose-response pattern for both males and females despite a very limited number of diabetic deaths. There is a clear need for further studies to evaluate the relationship of meat and other dietary habits to the frequency of diabetes utilizing more direct methods of measuring diabetes risk. 

So-called thermally stimulated current is the most direct method to investigate the nature of the traps, the current being due to the carriers comming out thermally from the traps. Although the thermally stimulated current of poly-N-vinylcarbazole has already been investigated by Pai (3) and Patora (4), the results are somewhat different. We investigated this problem with many... 

We, therefore, decided to study the reaction of a molecular stream passing through an exhausted enclosure which is permeated by radiation corresponding to a temperature that would be sufficient under ordinary circumstances to produce chemical reaction. Since, in the molecular stream, the gas is at so low a concentration that the mean free path is considerably longer than the length of the stream, the number of collision is negligible. This method seems, therefore, to offer a direct means of investigating the reaction due to radiation alone. 

THOMSON PARABOLA METHOD. The method of investigating the charge-to-mass ratio of positive ions in which the ions are acted upon by electric and magnetic fields applied in the same direction normal to the path of the ions. It can be shown that ions of a given charge-to-mass ratio but different velocities will be deflected so as to form a parabola. 

An analysis of chemical reactor stability and control-IX Further investigations into the direct method of Lyapunov (with R.B. Warden and N.R. Amundson). Chem. Eng. ScL 19,173-190 (1964). 

An experimental method of investigation which may indicate in a direct way the existence or nonexistence of heterogeneity for chemisorption has been devised by Itoginskil and collaborators 308). By this method the adsorption is performed in two steps by use of different isotopic forms. Should the surface be of a homogeneous nature, the adsorbed atoms would all be in the same condition. When, therefore, the gas is subsequently desorbed in two steps, the isotopic composition of the two portions should be the same. If, however, the surface has a heterogeneous character, the fraction of the gas added first during the adsorption process should be removed last from the surface during the desorption process and the desorbed fractions should have the same isotopic differences as the adsorbed portions. 

The most direct method of measuring the rate of production of radicals in a thermal decomposition would appear to be to lead the products of the reaction to a mass spectrometer, where the radicals could be identified by their mass numbers. Considerable technical difficulties are met with in the method, however, and so far relatively few communications have appeared dealing with its use, although several investigators are at present starting work on the subject. The pioneer work was done by Eltenton 2 and the principle of his method is as follows. 

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