INDEX matter

The physics of X-ray refraction are analogous to the well known refraction of light by optical lenses and prisms, governed by Snell s law. The special feature is the deflection at very small angles of few minutes of arc, as the refractive index of X-rays in matter is nearly one. Due to the density differences at inner surfaces most of the incident X-rays are deflected [1]. As the scattered intensity of refraction is proportional to the specific surface of a sample, a reference standard gives a quantitative measure for analytical determinations. 

Chemical Abstracts. These were commenced by the American Chemical Society in 1907. The abstracts are very comprehensive (particularly in recent years) from the standpoint of subject matter and journals covered. Four decennial indexes have appeared—1917, 1927, 1937 and 1947—and these are widely used for locating information pub lished during the period 1907-1947. The annual indexes cover the period 1948 to date. 

We desire to use the probability function derived above, so we recognize that the mass contribution of the volume element located a distance r from an axis through the center of mass is the product of the mass of a chain unit mp times the probability of a chain unit at that location as given by Eq. (1.44). For this purpose, however, it is not the distance from the chain end that matters but, rather, the distance from the center of mass. Therefore we temporarily identify the jth repeat unit as the center of mass and use the index k to count outward toward the chain ends from j. On this basis, Eq. (1.49) may be written as... 

We assign an index number to each of the polymer molecules and pick up the analysis of the problem after i polymer molecules have already been placed on an otherwise empty lattice. Our first question, then, concerns the number of ways the (i + l)th polymer molecule can be placed in the lattice. The polymer is to be positioned one repeat unit at a time, so it is an easy matter to count the number of available positions for the first segment of the (i + l)th molecule. Since the total lattice consists of N sites and ni of these are already occupied, the first segment of the (i + l)th molecule can be placed on any one of the N - ni remaining sites. 

Equations (10.17) and (10.18) show that both the relative dielectric constant and the refractive index of a substance are measurable properties of matter that quantify the interaction between matter and electric fields of whatever origin. The polarizability is the molecular parameter which is pertinent to this interaction. We shall see in the next section that a also plays an important role in the theory of light scattering. The following example illustrates the use of Eq. (10.17) to evaluate a and considers one aspect of the applicability of this quantity to light scattering. 

There are variations in representation of rings in different disciplines. The dye industry does not designate aromaticity or double bonds in rings. AH double bonds and aromaticity are shown in the Encyclopedia as a matter of course. For example, tetralin has an aromatic ring and a saturated ring and its stmcture appears in the Encyclopedia with its common name. Registry Number enclosed in brackets, and parenthetical CA index name, ie, tetralin [119-64-2] (1,2,3,4-tetrahydronaphthalene). With names and stmctural formulas, and especiaHy with CAS Registry Numbers, the aim is to help the reader have a concise means of substance identification. 

The US. Pharmacopeia (USP XXII) or National Formula (NFXVII) (20) also provide a similar description however, the peroxide value is not defined (Table 9). These specifications are also given in the Handbook of Pharmaceutical Excipients (HPE), pubhshed jointiy by the American Pharmaceutical Association and The Pharmaceutical Society of Great Britain (21), which defines lecithins both from plants and eggs. The Merck Index (22) specifies a slightiy lower acid value. The Japanese Monograph (ISCI-II) (23) specifies a slightiy lower acetone-insoluble matter and a lower heavy-metal content. 

Polarizability Attraction. AU. matter is composed of electrical charges which move in response to (become electrically polarized in) an external field. This field can be created by the distribution and motion of charges in nearby matter. The Hamaket constant for interaction energy, A, is a measure of this polarizability. As a first approximation it may be computed from the dielectric permittivity, S, and the refractive index, n, of the material (15), where is the frequency of the principal electronic absorption... 

The effects of rank on both compressive and impact strength have been studied, and usual minima were found at 20—25% dry, ash-free volatile matter (88—90 wt % carbon). Accordingly, the Hardgrove grindabiUty index exhibits maximum values in this area. 

The color of pure diatomite is white, or near white, but impurities such as carbonaceous matter, clay, iron oxide, volcanic ash, etc, may darken it. The refractive index ranges from 1.41 to 1.48, almost that of opaline siUca. Diatomite is optically isotropic. 

Wise, J.L. and L.C. Chhabildas (1986), Laser Interferometer Measurements of Refractive Index in Shock-Compressed Materials, in Shock Waves in Condensed Matter (edited by Y.M. Gupta), Plenum, New York, pp. 441-454. 

The Encyclopedia includes 253 alphabetically arranged entries written by 170 authors. The text is supplemented with more than 600 photographs, illustrations, sidebars, and maps. Entries contain a set of cross-references to related entries within the set, as well as a bibliography of related books and journal articles to guide readers who want to learn more about a given topic. The front matter in Volume 1 includes a list of entity topics, and the back matter in Volume 3 contains both an extensive timeline of important dates in energy history and a comprehensive subject index. 

However, if one lacks access to these, one may consult Chemical Titles and the keyword index (p. 1611) at the end of each issue of CA. In these cases, of course, it is necessary to know what name might be used for the compound. The name is not necessary for Index Chemicus (p. 1622) one consults the formula indexes. However, these methods are far from complete. Index Chemicus lists primarily new compounds, those which would not have been found in the earlier search. As for chemical Titles, the compound can be found only if it is mentioned in the title. The keyword indexes in CA are more complete, being based on internal subject matter as well as title, but they are by no means exhaustive. Furthermore, all three of these publications lag some distance behind the original journals. To locate all references to a compound after the period covered by the latest semiannual formula index of CA, it is necessary to use CAS-online. 

The compound index lists individual, fully specified compositions of matter that are mentioned in the text. It is an index of empirical formulas, ordered according to the following system the elements within a given formula occur in alphabetical sequence except for C, or C and H if present, which always come first. Thus, the empirical formula... 

This index comprises subject matter from Volumes 55 through 59. For subjects in previous volumes, see the cumulative index in Volume 54 which covers Volumes 50 through 54, and either the cumulative indices in each of the Collective Volumes I-V, or the single volume entitled Organic Syntheses, Collective Volumes I, II, III, IV, V, Cumulative Indices, edited by R. L. Shriner and R. H. Shriner. 

If there had been better communication between humanists and technologists, philosophers might already have resolved the matter of how computer ethics should be viewed. Of the forty-two articles listed in the Philosopher s Index under the category computer ethics, at least a dozen either focused on or touched upon the place of computer ethics in the pantheon of philosophy [see, e.g., 5-12]. The most basic question facing philosophers is the uniqueness of computer ethics. 

This leads to the concept of therapeutic index. The potency of a drug is almost irrelevant. It is its specificity that matters. Thus if two drugs A and B are effective at the same dose in a patient, say 1 mg, but A produces toxic effects at 10 mg which are only seen with 500 mg of B then B is clearly a much safer drug than A, in that patient. The ratio of toxic to effective dose is the therapeutic index (TI). It is often expressed as... 

Another variation of the preceding method is to apply HPLC to fractionate the cleaned-up aliphatic-aromatic fraction from flash colurim separation of soluble organic matter as it is performed in the Chevron laboratory, for example, as described in Reference 2. A Waters HPLC system equipped with a preparative Whatman Partisil 10 silica column (9.4 X 500 mm), a HPLC pump, and two detectors for separation monitoring (a UV and refractive index detector) are used, giving three fractions of aliphatic hydrocarbons, mono-, di-, and triaromatics and polar compounds. The hrst two fractions are eluted with hexane, whereas polar compounds are eluted with... 

When one has a planar surface, one can take advantage of X-ray optics to enhance surface sensitivity.61,62 The most important is specular or mirror reflection, and this is due to the fact that at X-ray energies the index of refraction of matter is slightly less than one and is given by ... 

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