Binary studies

In addition, simple binary studies with key excipients should be done to establish physical and chemical compatibility between the API and the selected excipient. These studies need not be elaborate, but will provide useful information to the formulator during the critical drug product development stage. 

The interaction energy parameter owns two forms according the binary studied ... 

Because key excipients are well established in most new product and process development programs, the same degree of preformulation scrutiny is often not required. Compatibility studies with the API, however, should be performed to study possible untoward interactions between the active ingredients and the excipients. It should be kept in mind that small or minor changes in physical and possibly chemical properties upon intimate contact in binary studies with key excipients should not automatically exclude a favored excipient without further critical testing. 

The quasi-binary study involved CO2 and the homologous series of the 1-alkanols, where the average carbon number of the 1-alkanols was varied from 4 to 6. In all systems mentioned, several transitions between different types of fluid phase behavior occur within a relatively small concentration range of the solvent. 

Contact angle will vary with liquid composition, often in a regular way as illustrated in Fig. X-13 (see also Ref. 136). Li, Ng, and Neumann have studied the contact angles of binary liquid mixtures on teflon and found that the equation of state that describes... 

Alkanethiols and other sulfur-bearing hydrocarbons covalently attach to metal surfaces alkanethiol onto gold is the most widely studied of these systems [27-29,31,32,45]. These SAMs are ordered provided the alkane chain contains nine or more carbons [32]. Binary solutions of two alkanethiols also appear... 

There is a number of very pleasing and instructive relationships between adsorption from a binary solution at the solid-solution interface and that at the solution-vapor and the solid-vapor interfaces. The subject is sufficiently specialized, however, that the reader is referred to the general references and, in particular, to Ref. 153. Finally, some studies on the effect of high pressure (up to several thousand atmospheres) on binary adsorption isotherms have been reported [154]. Quite appreciable effects were found, indicating that significant partial molal volume changes may occur on adsorption. 

Ionov S I, Ionov P I and Wittig C 1994 Time resolved studies of photoinitiated reactions in binary and larger (N2O) r,(HI) complexes Discuss. Faraday Soc. 97 391-400... 

Detailed x-ray diffraction studies on polar liquid crystals have demonstrated tire existence of multiple smectic A and smectic C phases [M, 15 and 16]. The first evidence for a smectic A-smectic A phase transition was provided by tire optical microscopy observations of Sigaud etal [17] on binary mixtures of two smectogens. Different stmctures exist due to tire competing effects of dipolar interactions (which can lead to alternating head-tail or interdigitated stmctures) and steric effects (which lead to a layer period equal to tire molecular lengtli). These... 

Apart from the Knudsen limit equations (12.12), the only other reasonably compact solution of the dusty gas model equations is that given by equations (5.26) and (5.27), corresponding to binary mixtures. Consequently, if we are to study anything other than the Knudsen limit, attention will... 

The thermodynamic study of thiazole and of some of its binary mixtures with various solvents has led to the determination of important practical data, but also to the discovery of association phenomena between thiazole and some solvents and of thiazole self-association. 

The first binary mixture quantitatively studied was the water-thiazole system, thiazole being a very hygroscopic compound (104), Determining the purity of thiazole sample obtained by distillation, Metzger and Distel-dorf (287) observed the existence of a stable azeotropic mixture, the characteristics of which are the following ... 

A large number of thermodynamic studies of binary systems were undertaken to find and determine eventual intermolecular associations for thiazole Meyer et al. (303, 304) discovered eutectic mixtures for the following systems -thiazole/cyclohexane at -38.4°C, Wt = 0.815 -thiazole/carbon tetrachloride at -60.8°C, Mt = 0.46 -thiazole/benzene at -48.5°C, nr = 0.70. 

A parallel study of liquid-vapor equilibrium was reported by Bares et al. for thiazole-CCl4 and thiazole-C<,Hi2 binary mixtures (311). 

The conclusion of all these thermodynamic studies is the existence of thiazole-solvent and thiazole-thiazole associations. The most probable mode of association is of the n-rr type from the lone pair of the nitrogen of one molecule to the various other atoms of the other. These associations are confirmed by the results of viscosimetnc studies on thiazole and binary mixtures of thiazole and CCU or QHij. In the case of CCU, there is association of two thiazole molecules with one solvent molecule, whereas cyclohexane seems to destroy some thiazole self-associations (aggregates) existing in the pure liquid (312-314). The same conclusions are drawn from the study of the self-diffusion of thiazole (labeled with C) in thiazole-cyclohexane solutions (114). 

Alloys. Many Ge alloys have been prepared and studied. Most have been made by melting Ge with another metal, much as germanides are made. Collections of binary phase diagrams and comments about many Ge alloys are available (25—28). 

Xenon dichloride [13780-38-6], XeCl, and xenon(II) chloroduoride [73378-52-6], XeClE, have been prepared by photochemical and electric discharge methods and have been examined at low temperatures by matrix-isolation techniques (39,40). The dichloride has a linear stmcture like that of XeE2. Evidence for the existence of XeCl2, XeBr2, and xenon tetrachloride [14989-42-5], XeCl, has been obtained from Mn ssbauer studies (41,42). Owing to thermal chemical instabiUties, no dihaUde other than the binary duorides has been prepared in macroscopic amounts. 

Ternary Blends. Discussion of polymer blends is typically limited to those containing only two different components. Of course, inclusion of additional components may be useful in formulating commercial products. The recent Hterature describes the theoretical treatment and experimental studies of the phase behavior of ternary blends (10,21). The most commonly studied ternary mixtures are those where two of the binary pairs are miscible, but the third pair is not. There are limited regions where such ternary mixtures exhibit one phase. A few cases have been examined where all three binary pairs are miscible however, theoretically this does not always ensure homogeneous ternary mixtures (10,21). 

Boron subhaHdes are binary compounds of boron and the halogens, where the atomic ratio of halogen to boron is less than 3. The boron monohaUdes, BCl, [20583-55-5] bromoborane(l) [19961-29-6] BBr, and iodoborane(l) [13842-56-3] BI, are unstable species that have been observed spectroscopicaHy when the respective ttihaUdes were subjected to a discharge (5). Boron dihaUde radicals have been studied, and stmctural and thermochemical data for these species ( BX2) have been deduced (5). 

Matthews-Akgerman The free-volume approach of Hildebrand was shown to be valid for binary, dilute liquid paraffin mixtures (as well as self-diffusion), consisting of solutes from Cg to Cig and solvents of Cg and C o- The term they referred to as the diffusion volume was simply correlated with the critical volume, as = 0.308 V. We can infer from Table 5-15 that this is approximately related to the volume at the melting point as = 0.945 V, . Their correlation was vahd for diffusion of linear alkanes at temperatures up to 300°C and pressures up to 3.45 MPa. Matthews et al. and Erkey and Akger-man completea similar studies of diffusion of alkanes, restricted to /1-hexadecane and /i-octane, respectively, as the solvents. 

Earlier studies of ion scattering were directed primarily at gas-ion interactions. As studies of ion—solid surfaces became common the energy of the scattered ions was eventually related mathematically to a simple binary elastic event involving a single atom on a surface element and a single probe ion. 

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