Big Chemical Encyclopedia

Chemical substances, components, reactions, process design ...

Articles Figures Tables About

Some Results

The whole field of theoretical calculation as it relates to solutions and solvent effects is currently very active. A useful review is that by Rotzinger (2005). It is not possible in a brief compass to mention all the important advances. We present a random selection of examples of this work, with no particular theme and without any attempt to be comprehensive. [Pg.126]

By microsolvation, we mean the assoeiation in the gas phase of a single eentral molecule or ion with a small number of another species that may be considered a ligand or a potential solvent. For calculation of solvation energies quantum mechanically, one would like to be able to start with a solute molecule. A, and a number of solvent molecules, B, and calculate to a certain level of theory the energy of A and B alone and then of a series of supermolecules or clusters A.B, A.2B, A.3B, and so on and a series of clusters 2B, 3B, and so on until the energy difference represented by [Pg.126]

Mass-spectrometric studies by Kebarle and coworkers (Arshadi et al, 1970 Kebarle, 1972) have enabled determination of the enthalpies of successive reactions (in the gas phase at low pressures, in the presence of a gas such as nitrogen or methane, which functions both as a heat bath and as a chemical ionization carrier) of the types [Pg.127]

The similar hydration of hydroxide ion greatly reduces its energy, an observation that is consonant with the great increase in the chentical activity of OH as the concentration of water in a solution of NaOH in ntixed DMSO/water solvent is decreased (see Chapter 6). [Pg.127]

The successive values of -A7/ j for the alkali hydrates recorded in Table 5.2 fall off smoothly, showing no favored coordination number (Fig. 5.8). Notably, this is [Pg.127]


The performance of the classifier has been verified using a number of practical applications, such as civil engineering [3], inspection of aerospace composite structures, ball bearings and aircraft multi-layer structures. Here we present shortly some results, focusing on detection of disbonds in adhesively joint multi-layer aerospace structures using Fokker Bond Tester resonance instrument, details can be found in [1]. [Pg.107]

This paper is structured as follows in section 2, we recall the statement of the forward problem. We remind the numerical model which relates the contrast function with the observed data. Then, we compare the measurements performed with the experimental probe with predictive data which come from the model. This comparison is used, firstly, to validate the forward problem. In section 4, the solution of the associated inverse problem is described through a Bayesian approach. We derive, in particular, an appropriate criteria which must be optimized in order to reconstruct simulated flaws. Some results of flaw reconstructions from simulated data are presented. These results confirm the capability of the inversion method. The section 5 ends with giving some tasks we have already thought of. [Pg.327]

The results regarding resolution as measured by CERL double wire IQI s show results for a class G2 film very close to those obtained by X-rays. Some results from the large range of published data are summarized in fig. 5 and 6. [Pg.426]

The uncertainties in choice of potential function and in how to approximate the surface distortion contribution combine to make the calculated surface energies of ionic crystals rather uncertain. Some results are given in Table VII-2, but comparison between the various references cited will yield major discrepancies. Experimental verification is difficult (see Section VII-5). Qualitatively, one expects the surface energy of a solid to be distinctly higher than the surface tension of the liquid and, for example, the value of 212 ergs/cm for (100)... [Pg.268]

The calculation of the time evolution operator in multidimensional systems is a fomiidable task and some results will be discussed in this section. An alternative approach is the calculation of semi-classical dynamics as demonstrated, among others, by Heller [86, 87 and 88], Marcus [89, 90], Taylor [91, 92], Metiu [93, 94] and coworkers (see also [83] as well as the review by Miller [95] for more general aspects of semiclassical dynamics). This method basically consists of replacing the 5-fimction distribution in the true classical calculation by a Gaussian distribution in coordinate space. It allows for a simulation of the vibrational... [Pg.1057]

Flartree D R, Flartree W and Swirles B 1940 Self-oonsistent field inoluding exohange and superposition of oonfigurations with some results for oxygen Phil. Trans. R. See. A 238 229-47 The work of Fook is given in ... [Pg.2194]

In the theory of the liquid state, the hard-sphere model plays an important role. For hard spheres, the pair interaction potential V r) = qo for r < J, where d is the particle diameter, whereas V(r) = 0 for r s d. The stmcture of a simple fluid, such as argon, is very similar to that of a hard-sphere fluid. Hard-sphere atoms do, of course, not exist. Certain model colloids, however, come very close to hard-sphere behaviour. These systems have been studied in much detail and some results will be quoted below. [Pg.2668]

Some results of these studies will be presented in Sections XV.A.1-XV.A.3. [Pg.699]

Despite these similarities between the G2 calculations of Dg for H2 and Hj, there is a profound difference that is only hinted at in the single-point energies in Table 10-1. In the first group of results we see that all the calculations, with the exception of the last one, give the same answer. In the lower block of results, for H2, this is not the case. Some results are duplicated and some are not. The results are more mixed. [Pg.309]

The conjugation of three unsaturated centres results in a further increase in Xmax. 3 d Cmax.- Some results are given in Table X. [Pg.1146]

The ah initio module can run HF, MP2 (single point), and CIS calculations. A number of common basis sets are included. Some results, such as population analysis, are only written to the log file. One test calculation failed to achieve SCF convergence, but no messages indicating that fact were given. Thus, it is advisable to examine the iteration energies in the log file. [Pg.329]

Some results obtained by the HMO method (one of the more useful for reactivities comparisons) are summarized in Tables III-17 and III-18. [Pg.358]

In order to draw some conclusions about viscosity from the reptation model, it is again necessary to anticipate some results from Chap. 9 on diffusion. The... [Pg.120]

The melting points of a series of poly(a-olefin) crystals were studied. All of the polymers were isotactic and had chain substituents of different bulkinesses. Table 4.2 lists some results. Use Eq. (4.5) as the basis for interpreting the trends in these data. [Pg.209]

Figure 8.39 shows some results of EXAFS following absorption by iron atoms in proteins with three prototype iron-sulphur active sites. In the example in Figure 8.39(a) application of a 0.9-3.5 A filter window before Fourier retransformation shows a single wave resulting... [Pg.331]

Puel J.P. (1987) Some results on optimal control for unilateral problems. Gout. Partial Diff. Equat. Lect. Notes in Control and Infor. Sci. 114, Springer-Verlag, 225-235. [Pg.384]

The classical experiment tracks the off-gas composition as a function of temperature at fixed residence time and oxidant level. Treating feed disappearance as first order, the pre-exponential factor and activation energy, E, in the Arrhenius expression (eq. 35) can be obtained. These studies tend to confirm large activation energies typical of the bond mpture mechanism assumed earlier. However, an accelerating effect of the oxidant is also evident in some results, so that the thermal mpture mechanism probably overestimates the time requirement by as much as several orders of magnitude (39). Measurements at several levels of oxidant concentration are useful for determining how important it is to maintain spatial uniformity of oxidant concentration in the incinerator. [Pg.57]

Some results of the constant-value pricing system are as foUow generation in a central unit at relatively low pressure, <4.24 MPa (600 psig) tremendous economic pressure to use turbines rather than motors for drives lack of incentive for high efficiency turbines excessively high temperature differentials in steam users tremendous incentive to recover waste heat as low pressure steam and a large plume of excess low pressure steam vented to the atmosphere. [Pg.92]

The results of several studies were interpreted by the Poole-Erenkel mechanism of field-assisted release of electrons from traps in the bulk of the oxide. In other studies, the Schottky mechanism of electron flow controlled by a thermionic emission over a field-lowered barrier at the counter electrode oxide interface was used to explain the conduction process. Some results suggested a space charge-limited conduction mechanism operates. The general lack of agreement between the results of various studies has been summari2ed (57). [Pg.331]

The replacement of asbestos fibers by other fibrous materials has raised similar health issues in relation to substitute materials. However, since lung cancer has a latency period of approximately 25 years, and since the fiber exposure levels in contemporary industries is far lower than those which prevailed half a century ago, the epidemiological data on most substitutes is insufficient. A possible exception is slag fibers for which several studies on worker populations are available over extended periods (44) some results show a substantial increase in lung cancer occurrence. Consequentiy, the toxicity of asbestos substitute fibers remains a subject of active investigation. [Pg.356]

In the [3,2-c ] series the spectra of the parent compound and some closely related analogues have been compared with those predicted from MO calculations of electron densities. The results confirm the predicted occiurence of a considerable degree of bond localization in these compounds <80KGS54l), as was previously found in their deaza (cinnoline) analogues <67JCS(B)1243). Other comparisons of NMR values with those expected from MO calculations for a series of azanaphthalenes have included some results with pyridopyridazines <75MI21500). [Pg.234]

Substituted 1,3-azoles exist in two non-charged tautomeric forms (156) and (157) together with the zwitterlonic form (158). 5-Substltuted 1,3-azoles also exist in forms (159) and (160) together with the zwitterlonic forms (161). Some results are summarized in Table... [Pg.37]

In the section dealing with electrophilic attack at carbon some results on indazole homocyclic reactivity were presented nitration at position 5 (Section 4.04.2.1.4(ii)), sulfon-ation at position 7 (Section 4.04.2.1.4(iii)) and bromination at positions 5 and 7 (Section 4.04.2.1.4(v)). The orientation depends on the nature (cationic, neutral or anionic) of the indazole. Protonation, for instance, deactivates the heterocycle and directs the attack towards the fused benzene ring. A careful study of the nitration of indazoles at positions 2, 3, 5 or 7 has been published by Habraken (7UOC3084) who described the synthesis of several dinitroindazoles (5,7 5,6 3,5 3,6 3,4 3,7). The kinetics of the nitration of indazole to form the 5-nitro derivative have been determined (72JCS(P2)632). The rate profile at acidities below 90% sulfuric acid shows that the reaction involves the conjugate acid of indazole. [Pg.259]

Finally, some results obtained from indazoles substituted in the carbocycle are of interest, even though in these cases the reaction does not involve the heterocyclic moiety (Section 4.04.2.3.2(ii)). For example, pyrazolo[3,4-/]- (566) and pyrazolo[4,3-/]-quinolines (567) have been obtained from aminoindazoles by the Skraup synthesis (76JHC899). Diethylethoxy-methylenemalonate can also be used to give (566 R = C02Et, R = OH) (77JHC1175). Pyrazolo-[4,3-/]- and -[4,3-g]-quinazolones (568) and (569) have been obtained from the reaction of formamide with 5-amino-4-methoxycarbonyl- and 6-amino-5-carboxyindazole, respectively (81CB1624). [Pg.273]

Some results have been published on 2-alkylisothiazole-3- and -5-thiones (75CJC836, 80JCS(P 1)2693). As expected, the resonance of the carbon attached to the exocyclic sulfur atom is shifted downfield, to around 185 p.p.m. in the case of the 3-thiones and to over 190p.p.m. for the 5-thione. It is possible that CNMR chemical shifts could be used to investigate tautomerism in related compounds. Saccharin has carbon resonances at 161.0 (3), 127.9 (3a), 125.1 (4), 134.7 and 135.5 (5 and-6), 121.2 (7) and 139.5 (7a) p.p.m. in DMSO solution <82UP41700>. [Pg.138]

Some results of the reduction of hematite by graphite at 907 to 1,007°C in the presence of lithium oxide catalyst were correlated by the equation 1 — (1 — xY = kt. The reaction of solids ilmenite and carbon has the mechanism... [Pg.2124]

Some results of actual measurements are shown next on Figure 3.5.2 and Figure 3.5.3. [Pg.69]

A frequency response technique was tried first and some results were received. The useful frequency domain was less than one order of magnitude, while in electrical problems five orders of magnitude can be scanned. The single pulse technique was more revealing, but evaluation by moments had the usual accumulation of errors. Fourier transform of the pulse test results was the final method. [Pg.156]


See other pages where Some Results is mentioned: [Pg.354]    [Pg.15]    [Pg.542]    [Pg.336]    [Pg.347]    [Pg.654]    [Pg.710]    [Pg.567]    [Pg.2106]    [Pg.2680]    [Pg.483]    [Pg.177]    [Pg.42]    [Pg.344]    [Pg.12]    [Pg.94]    [Pg.167]    [Pg.182]    [Pg.465]    [Pg.281]    [Pg.713]    [Pg.292]    [Pg.284]   


SEARCH



A some PCA results

Comparison between Experimental Results Obtained with Hydroxylated Polyacids and some Theoretical Models

Methods of Measurement and Some Results

Oscillatory reactions some exact results

Preparation of Copper Anions and Some Resulting Chemistry

Results Some Preliminary Comments

SOME IMPORTANT EXPERIMENTAL RESULTS ON GAS MOTION IN POROUS MEDIA AND CAPILLARIES

Some Characteristics of Numerical Results

Some Comments About the Experimental Results

Some Computed Simulation Results for Steam Reformers

Some Experimental Results

Some Fundamental Results for Surface Spread

Some General Theoretical Results

Some Geochemical Principles and Results

Some Mapping Results Obtained with Photographs from the Various Gemini Satellites

Some Molecular Orbital Results

Some Numerical Results

Some Other Experimental Results

Some Previous Results

Some Project Results

Some Results from Conceptual DFT

Some Results with Unsaturated Molecules

Some Typical Results

Some Valence Bond Results

Some Viscoelastic Results

© 2024 chempedia.info