Exploratory experiments

Most workers in exploratory experiments use high grade solvents for it helps avoid complicating factors. Results thus obtained cannot necessarily be extrapolated safely to technical, reused, or reclaimed solvents, and serious errors have been made by doing so. If, in commercial practice, a lower grade solvent is to be used, its effect on the catalyst should be ascertained beforehand. 

Table 3-1. Exploratory Experiments with Various Gases ...

Several exploratory experiments were made with unlabeled 1,2-dihydronaphthalene, either neat or with 10% dibenzyl, at 450°C. The runs were made using an agitated 10 cc reactor which was immersed in a preheated sand bath to achieve rapid heating and cooling. It is first noted that the products from... 

Exploratory experiments with dictyotene and suspensions of male gametes of E. siliculosus showed a significantly enhanced production of the 6-butylcyclohepta-2,4-dienol and its isomers. This indicates that a biological degradative pathway does exist and that this pathway follows the same oxidative sequence as the abiotic route. However, final conclusions about the biotic contribution to the pheromone transformation cannot be drawn before careful analysis of the degree of enantioselectiv-ity of the biotic reaction. 

Some exploratory experiments with ethyl vinyl ether showed that it polymerised too rapidly for our method to be useful. The polymerisation of 2-methyl butene-2 had a manageable rate but the results showed inconsistencies which we did not have time to resolve, as this was the last monomer to be studied. 

The initiators were salts with reactive cations and stable and inert anions, so that the initiation should be fast and as unambiguous as possible, and there would be no scope for any BIE, involving the growing ends. Some exploratory experiments with HC104 and HSO3CF3 showed that these are unsuitable for kinetic work, because of the formation of conjugate anions of the type A2H". 

The situation would be completely different for oxycarbenium ions in a highly polar solvent such as sulphur dioxide which could compete effectively as solvating agent with the DCA and their polymers. In such systems one could envisage that both the solvent-solvated oxycarbenium ions and also the solvent-solvated teJt.-oxonium ions could coexist in a true equilibrium, and that each would react according to its own characteristics. This is an area which remains very largely unexplored, although Penczek has made a start in this direction and these considerations arose from discussions with him of his exploratory experiments with sulphur dioxide as solvent. 

The Low-temperature Polymerisation of Isobutene, Part IV, Exploratory Experiments, R.H. Biddulph and P.H. Plesch, Journal of the Chemical Society, 1960, 3913-3920. 

To improve the rate of reduction the amino alcohol ligand of the ruthenium complexes was exchanged for monotosylated 1,2-diamine ligands. For exploratory experiments AT-tosylethane-1,2-diamine was prepared hy monotosylation of ethane-1,2-diamine and attached to the primary face of P-CD yielding 80. With P-CD as the only chiral unit the ruthenium complex of 80 could reduce aromatic and aliphatic standard ketones 63 and 69 in 91% 5deld, 25% ee (S) and 68% 5deld, 58% ee, respectively, within only 4h under standard conditions (Fig. 24). 

In an exploratory experiment, 13 different powder materials were tested in a FFB ACE unit. Most of the results were unremarkable except for three catalysts a low Z/M commercial maximum distillate catalyst (the same LZM catalyst used in the pilot riser experiment), a spray dried low surface area silica (inert) and the minimum aromatics breakthrough (MAB) catalyst. The inert material was included in the study to represent thermal cracking. The catalysts were steam deactivated in the fixed bed steamer prior to testing. Catalysts and the VGO-B feed properties are displayed in Tables 2.3 and 2.1, respectively. LCO aromatics were measured with 2D GC. Figures 2.7 through 2.9 illustrate the main results. 

Some exploratory experiments have also been carried out with some phosphate esters. Rate constants for one of these, dinitrophenyl-phosphate, are listed in Table VII. With this substrate, surprisingly, the intrinsic primary amines of the polymer seem to be acting in a turnover pathway, that is, are phosphorylated and then dephosphorylated, but this mechanism needs to be better substantiated. In any event it, it is clear that the rates in the presence of polymer are accelerated more than 103-fold with dinitrophenylphosphate. Even larger accelerations have been observed with other phosphate esters. 

Changes in the composition of the slices and/or incubation medium give some indication of metabolic activity, but extensive damage may be caused to the cells on slicing the system is so artificial that data obtained by the tissue slice technique may not pertain to the physiological situation. However, the technique is widely used at least for introductory, exploratory experiments. 

For the benefit of those readers who might feel that we are basing far-reaching conclusions on the results of one system, namely nitrogen on tungsten, we add that exploratory experiments similar to those described... 

Volatile buffers were reconsidered for the modified method. Triethylamine was ruled out primarily because it could not be obtained in high purity and because the secondary and primary amines contaminating it could potentially react with solutes present in the water sample. Preliminary evidence of reaction between ethidium bromide and triethylammonium bicarbonate was obtained, but the reaction product was not characterized. The components of volatile buffers that appeared acceptable on the basis of chemical purity were ammonia, acetic acid, and formic acid. A few exploratory experiments were conducted involving the elution by ammonium formate and ammonium acetate of EB or quinaldic acid exchanged onto AG MP-50 or IRA 900. These experiments showed that 1 M ammonium formate in water was a very poor eluent, but that EB could be eluted from AG MP-50 with 1 M ammonium formate in methanol. Elution was essentially complete with 6 bed volumes of the methanolic eluent, whereas neither methanol alone nor aqueous 1 M ammonium formate was able to elute this solute. This situation pointed out the necessity for a counterion to displace exchanged solutes and, additionally, indicated that the displaced solute be highly soluble in the eluting solvent. 

Figure 18.10 Simple vacuum electrochemical cell that is suitable for direct freeze-pump-thaw of the solution. It is very useful for rapid exploratory experiments under vacuum. [From Ref. 39.]...

The experimental work can be divided into two general classes (1) exploratory experiments to find ion exchange resins suitable for the proposed application, and (2) obtaining quantitative data on one resin pair selected. 

Blair, J. S. Godar, E. M. Masters, J. E. Riester, D. W. Exploratory experiments to identify chemical reactions causing flavor deterioration during storage of canned orange juice. I. Incompatibility of peel oil constituents with the acid juice. Food Res., 1952, 17, 235-260. 

Exploratory experiments could test hypotheses, see whether popular beliefs were well founded, or involve the invention of instruments, which could produce new phenomena by reducing nature to alter her course. The same experimental procedures in different contexts could be either exploratory or probatory distillation, for example, could determine whether a drug was pure or could be used to discover the drug s chemical constituents. 

As mentioned earlier, probably the most promising application of a-Si H FETs is their use in addressable liquid crystal displays, which will be discussed in the following Chapter. Here we shall review the results of some exploratory experiments on the application of the FETs to a number of logic and image-sensing circuits. 

Exploratory experiments in thawing and drying randomly selected materials from the museums collection were conducted. Frozen flood-damaged books and file materials that the librarians knew could be discarded or replaced were chosen for the initial experiments. The dielectric grid current was kept constant as the plate current or electrode separation space was varied according to the size of the frozen library materials and an estimate of the water they contained. 

As has already been illustrated in Sect. 2.1, carbons with their graphitic surface structure often adsorb aromatic compounds well and thereby affect their reaction rates. In order to test what influence carbons would have on the solvolysis of an aromatic ester, Spiro and Mills [172] carried out exploratory experiments on the alkaline hydrolysis of benzyl acetate at 25°C... 

Note that in this procedure the main decision required by the experimenter is the size of the dose. Of course, this will depend on the adsorption capacity of the sample and the number of experimental points desired. For a new, unknown sample, a first exploratory experiment with large doses is useful. Also, the fact that the final accuracy is an inverse function of the number of experimental points (because of the additivity of the errors made at each introduction of adsorptive) must be kept in mind. The introduction of the desired dose is made easier if the gas flow is restricted by a constriction or a needle valve. 

In studies carried out in the pH range of 3 to 6, it was necessary to buflFer the solutions, since Reaction 8 tends to increase the acidity. Only phosphate and pyrophosphate buffers were used almost all other buffer systems would be attacked by the OH or HO2 radical. (Fluoride buffers could probably be used, although there are difficulties associated with the measurement of pH.) In addition, early exploratory experiments, not reported in detail here, indicated that spurious results would be obtained in buffers containing unpurified alkali. In these experiments the rate of reaction was much more rapid than in pyrophosphate buffers which did not contain alkali, and somewhat lower values of R were observed. 

FIG. 1. The four stages of a rat reasoning task are shown. First (A), the rat is given an exploratory experience in which it has the run of the maze in the absence of any food reinforcement. Second (B), the rat is fed in one of the arms and is prevented from re-entering the rest of the maze. In the test component the rat is removed to a separate start arm and the target arm rebaited (C). The rat can then combine his two prior experiences to chart a direct accurate course to the reward (solid line in D) or may enter another arm, which is scored as an error (dashed line in D). 

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