Critical evaluating

For a recent critical evaluation of situations where current DFT approaches experience difficulties, see Davidson E R 1998 How robust is present-day DFT ... 

The Beilstein database [20] has more than 8.3 million (October, 2002) organic substance records from the Beilstein Handbook and abstracted from about 180 journals in organic chemistry from 1779 to the present. AH documents are critically evaluated and peer-reviewed. 

NISTFLUIDS U.S. Department of Commerce National Institute of Standards and Technology critically evaluated thermophysical and transport porperties for 12 important iadustrial fluids... 

National Library of Medicine, NIOSH s Registy of Toxic Effects Chemical Substances (RTECS) database, Nov. 1994 rev. the data have not been critically evaluated. 

Artificial surfaces must be resistant to cigarette bums, vandaUsm, and other harm. Fire resistance is most critically evaluated by the NBS flooring radiant panel test (10). In this test, a gas-fired panel maintains a heat flux, impinging on the sample to be tested, between 1.1 W/cm at one end and 0.1 W/cm at the other. The result of the bum is reported as the flux needed to sustain flame propagation in the sample. Higher values denote greater resistance to burning results depend on material and surface constmction. Polypropylene turf materials are characterized by critical radiant flux indexes which are considerably lower than those for nylon and acryflc polymers (qv) (11). 

A sampling of appHcations of Kamlet-Taft LSERs include the following. (/) The Solvatochromic Parameters for Activity Coefficient Estimation (SPACE) method for infinite dilution activity coefficients where improved predictions over UNIEAC for a database of 1879 critically evaluated experimental data points has been claimed (263). (2) Observation of inverse linear relationship between log 1-octanol—water partition coefficient and Hquid... 

The molecules in a gas-hquid interface are in tension and tend to contract to a minimum surface area. This tension may be quantified by the surface tension, which is defined as the force in the plane of the surface per unit length. Jasper" has made a critical evaluation of experimental surface tension data for approximately 2200 pure chem-ic s. He correlates surface tension C (mN/m = dyn/cm) with temperature T (°C) over a specified temperature range as... 

Critical evaluation of data to determine controlling granulation mechanisms... 

TJA Ewing, ID Kuntz. Critical evaluation of search algorithms for automated molecular docking and database screening. J Comput Chem 18 1175-1189, 1997. 

Having demonstrated that our simulation reproduces the neutron data reasonably well, we may critically evaluate the models used to interpret the data. For the models to be analytically tractable, it is generally assumed that the center-of-mass and internal motions are decoupled so that the total intermediate scattering function can be written as a product of the expression for the center-of-mass motion and that for the internal motions. We have confirmed the validity of the decoupling assumption over a wide range of Q (data not shown). In the next two sections we take a closer look at our simulation to see to what extent the dynamics is consistent with models used to describe the dynamics. We discuss the motion of the center of mass in the next section and the internal dynamics of the hydrocarbon chains in Section IV.F. 

In numerous applications of polymeric materials multilayers of films are used. This practice is found in microelectronic, aeronautical, and biomedical applications to name a few. Developing good adhesion between these layers requires interdiffusion of the molecules at the interfaces between the layers over size scales comparable to the molecular diameter (tens of nm). In addition, these interfaces are buried within the specimen. Aside from this practical aspect, interdififlision over short distances holds the key for critically evaluating current theories of polymer difllision. Theories of polymer interdiffusion predict specific shapes for the concentration profile of segments across the interface as a function of time. Interdiffiision studies on bilayered specimen comprised of a layer of polystyrene (PS) on a layer of perdeuterated (PS) d-PS, can be used as a model system that will capture the fundamental physics of the problem. Initially, the bilayer will have a sharp interface, which upon annealing will broaden with time. 

Information about this splendid compilation came to me from a chemist, Robert Weast (1985), who was editor from 1952 until 1988... 37 years He also informed me that the creation (jointly by the American Chemical Society and the American Institute of Physics) of the Journal of Physical and Chemical Reference Data, which began publication in 1972, was encouraged by the results of a survey which indicated how widely the Rubber Bible was used. Weast describes this journal as a truly outstanding source of critically evaluated data . In saying this, he underlined the crucial role of editors and contributors critical judgment in selecting data for such compilations. David Tide, the editor of the journal, in 1989 succeeded Robert... 

The relative merits of various MO methods have been discussed in die literature. In general, the ab initio type of calculations will be more reliable, but the semiempirical calculations are faster in terms of computer time. The complexity of calculation also increases rapidly as the number of atoms in the molecule increases. The choice of a method is normally made on the basis of evidence that the method is adequate for the problem at hand and the availability of appropriate computer programs and equipment. Results should be subjected to critical evaluation by comparison widi experimental data or checked by representative calculations using higher-level mediods. Table 1.12 lists some reported deviations from experimental AHf for some small hydrocarbons. The extent of deviation gives an indication of the accuracy of the various types of MO calculations in this application. 

While the foregoing concepts have been utilized to rationalize the product distribution obtained on hydrogenation of a number of monocyclic olefins, it should be noted that the effect of pressure on the stereochemistry of hydrogenation of steroidal double bonds has not been critically evaluated. 

Failure Modes, Effects and Criticality Evaluation (FMECA) is a systematic qualitative metliod by which equipment and system failures and tlie resulting effects of these failures are detennined. FMECA studies possible events, but not tlie reasons for tlieir occurrences. 

The pyrotechnic literature does not contain a critical evaluation of the ignition response time. of primary initiators in terms of their compn, temp tolerance and shock sensitivity. In general, primary expls such as Pb Azide or styphnate are selected whenever a brief (microsecond) response is desired, while, for instance, Pb thiocyanate-chlorate mixts are selected when high temps and high radiation environments are encountered, and presumably a longer ignition delay is the price which is paid for the extra margin of safety... 

However, measurements of substituent effects supported the hypothesis that the aryl cation is a key intermediate in dediazoniations, provided that they were interpreted in an appropriate way (Zollinger, 1973a Ehrenson et al., 1973 Swain et al., 1975 a). We will first consider the activation energy and then discuss the influence of substituents, as well as additional data concerning the aryl cation as a metastable intermediate (kinetic isotope effects, influence of water acitivity in hydroxy-de-di-azoniations). Finally, the cases of dediazoniation in which the rate of reaction is first-order with regard to the concentration of the nucleophile will be critically evaluated. 

The provision of clinical data in support of conformity with the requirements of the directives does not necessarily mean that the device has to be subjected to actual clinical investigations. Instead, the manufacturer may present critical evaluations of... 

Pollard, T.D. Cooper, J.R. (1986). Actin and actin-binding proteins. A critical evaluation of mechanisms and functions. Ann. Rev. Biochem. 55, 987-1035. 

The targeted readership for this book is the scientifically literate nonspecialist. We encouraged the authors to present their material in a scientifically accurate and critically evaluated fashion understandable to those outside their discipline. This is always a very difficult task, and different authors took different approaches. Issues of disciplinarity are addressed by Brian Mar in his introduction. 

Examples were given earlier of a few systems for which the theoretical speciation of metals was calculated, and a few others in which it was analyzed experimentally, at least into some subgroups if not specific species. These approaches have rarely been combined to critically evaluate data or hypotheses regarding metal transport through a real system. One study, already noted... 

Chee K.K. A critical evaluation of the single-point determination of intrinsic viscosity. Journal of Applied Polymer Science 34, 3 (1987) 891-899. 

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