Subject crystalline structure

Liquid crystal polymers (LCP) are a recent arrival on the plastics materials scene. They have outstanding dimensional stability, high strength, stiffness, toughness and chemical resistance all combined with ease of processing. LCPs are based on thermoplastic aromatic polyesters and they have a highly ordered structure even in the molten state. When these materials are subjected to stress the molecular chains slide over one another but the ordered structure is retained. It is the retention of the highly crystalline structure which imparts the exceptional properties to LCPs. 

The majority of cluster technetium compounds are subject to thermal decomposition topochemically (i.e. their decomposition reaction occurs in the solid phase), [H(H20)2]2 [Tc8Br4( -Br)8]Br2 being an exception. This compound melts before decomposition (at 610-620 °C), which is good evidence in favour of the molecular crystalline structure of its dehydrated form [Tc8Br4(/i-Br)8]Br2. ... 

It must be recognized that, in general, the physical properties of any metal are dependent on (1) the crystalline structure of the metal, (2) the presence of impurities, and (3) the mode of production and the mechanical treatment to which the metal may have been subjected. 

Studies have been pubhshed on chemical interesterification of tallow with regular sunflower oil (96-98). Changes in the proportion of sunflower oil in blends with tallow produce httle modification of the solid content or the melting point. However, important modifications take place in the thermal properties of these blends when they are subjected to a process of chemical interesterification. In addition, modifications occur in the crystalline structure. Solid beef tallow—composed... 

Solvent can be associated with the solid in different chemical and physical states. It can be part of the crystalline structure, chemically adsorbed in solid interior or physically penetrated/adsorbed inside the interstices of the solid. The interstices of the solid are subjected to a large capillary tension upon drying. The force exerted to solid can be estimated by Laplace s law/ ... 

This hitherto neglected area is now receiving major attention and the crystalline structures of many common and uncommon bile acids [43,44,48,49], their alkaline and alkaline metal salts [7,51,53] have been defined. Choleic acids have been the subject of much activity in this field. A summary of the earlier work on choleic acids can be found in Sobotka [42] and Small [5]. 

As might be expected, the crystalline makeup and the uniformity of the sulfur coating are important, even more so for the sulfur-only material (10). The sulfur structure must be elastic and the urea must be evenly coated. Operating conditions must be controlled to give this structure. McClellan fully discusses the subject of sulfur crystalline structure in Chapter 2. 

While it is well known how the acid strength of Bronsted sites depends on the physicochemical parameters of a zeolite, the situation in the case of Lewis centers is much less established. In particular the influence of the chemical composition and crystalline structure on the more tenuous concept of softness and hardness of the metal sites is a subject of recent interest [1]. 

There have been many studies of the crystalline structures of elemental phosphorus [10,45], and the microscopic structures of the amorphous modifications (red, black, grey vitreous) are still the subjects of considerable attention. Gas phase clusters have been of interest for many years, and Martin [19] has detected mass spectroscopically clusters up to > 6000. Nevertheless, little experimental information was available until recently on the structure of clusters with > 4, and this is also true for arsenic clustere, As . 

To our knowledge this compound has been the subject of only one paper, Chander et al. (1978). The crystalline structure is given as primitive cubic with a = 3.145 A. This result seems unusual in comparison with other rare earth chalcogenides which always exhibit a fee NaCl-type, structure. (By multiplying the parameter by 2, it becomes 6.29 A, which is comparable to that of SmTe and TmTe.)... 

Zapanta-Le Geros et al. (1970) have recently reviewed the subject of infrared spectra of carbonate-containing synthetic and biological apatites. Klein et al. (1970) have used the polarized infrared specular-reflectance technique to study single crystals of apatites. They found this technique to be a more powerful method for the analysis of the vibration spectra of crystalline structures than the powder absorption techniques. 

Some cosmetic products are in the form of microemulsion gels. This name has emanated from the cosmetics industry from a colloidal viewpoint these gels are liquid crystals with cubic or hexagonal symmetry. The liquid crystalline structures per se are not the subject of this chapter reviews in that area are readily available [1-4]. 

The cotton fiber is subjected to many treatments that affect swelling and change its crystal structure. The agents employed must be able to interact with and disrupt the native crystalline structure in order to change it to different polymorphs. The chemical reactions of commerce generally involve the water-swollen fiber, which retains a highly crystalline... 

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