Internal cavity

Cyclodextrins are macrocyclic compounds comprised of D-glucose bonded through 1,4-a-linkages and produced enzymatically from starch. The greek letter which proceeds the name indicates the number of glucose units incorporated in the CD (eg, a = 6, /5 = 7, 7 = 8, etc). Cyclodextrins are toroidal shaped molecules with a relatively hydrophobic internal cavity (Fig. 6). The exterior is relatively hydrophilic because of the presence of the primary and secondary hydroxyls. The primary C-6 hydroxyls are free to rotate and can partially block the CD cavity from one end. The mouth of the opposite end of the CD cavity is encircled by the C-2 and C-3 secondary hydroxyls. The restricted conformational freedom and orientation of these secondary hydroxyls is thought to be responsible for the chiral recognition inherent in these molecules (77). 

These foams are used for board stock in commercial and industrial buildings as insulation for internal cavity and external walls, roof, floor, and foundations. Spray-appHed foam, covered subsequently with one of a variety of protective coatings, is widely used for large roofing appHcations and has limited use as external walls. Eor residential buildings, the principal use is as external sheathing board. 

Figure 3.8 Large tubercle broken open to reveal the internal cavity. The cavity is filled with fiuid in service.

Internal surfaces were moderately tuberculated (Fig. 3.14). Extremely thick, hard magnetite shells capped large internal cavities (Fig. 3.9). Pipe cross-sectional area was reduced by at least 30% in some places. Tubercles were aligned with flow, indicating that growth occurred during service. No failure occurred, and deepest metal loss was only 0.093 in. (0.033 cm) from the nominal pipe wall thickness of 0.225 in. (0.572 cm). 

Aimulene offers a particularly significant test of the Hiickel rule. The internal cavity in [18]annulene is large enough to minimize steric interactions between the internal hydrogens in a geometry that is free of angle strain. Most MO calculations find the delocalized structure to be more stable than the polyene. ... 

An important property of dendrimers is the presence of internal cavities in which ions or neutral molecules can be hosted [68]. Such a property can potentially be exploited for a variety of purposes, which include catalysis and drug delivery. 

Neutral carriers are organic complexing agents which are capable of sequestering and transporting ionic species in a hydrophobic organic phase. The antibiotics, valino-mycin and nonactin were the first neutral carriers to be incorporated in an ISE These macrocyclic neutral carriers contain a polar internal cavity and an outer hydro-phobic shell. The excellent selectivity exhibited by valinomycin for potassium ions is... 

This work demonstrates that functionalization of the internal cavities of various dendrimers can be done via a post modification of the skeleton. Various functional groups can be selectively introduced aminophosphite, aldehyde, hydrazone, dichlorophosphane sulfide. Therefore all the chemistry reported on the surface of dendrimers can be now envisaged to be done into the cavities and it is demonstrated for the first time that a macromolecular chemistry can be performed into the internal voids of a dendrimer. 

The cores of individual mammalian ferritin molecules are clearly visible by transmission electron microscopy as well defined nanoparticle crystallites encapsulated within the protein shell which can attain a size close to that of the 8 nm interior diameter of the protein shell (Massover, 1993). This is illustrated in Figure 6.13 for a sample of human ferritin. The amount of iron in the core is variable, and can range from zero to a maximum of approximately 4500 atoms (Fischbach and Anderegg, 1965) this corresponds to the capacity of the internal cavity for Fe(III) as... 

Avoid building blocks with interconnected internal cavities in basement walls. Basement walls made from in situ (poured) concrete are recommended. Concrete elements require careful and permanent sealing of all joints. Designs similar to swimming pools, manure tanks in agriculture and bomb shelters will provide a radon safe construction. 

Frye KJ, Royer CA. Probing the contribution of internal cavities to the volume change of protein unfolding under pressure. Protein Sci. 1998 7 2217-2222. 

A non-pneumatic tyre which has an internal cavity which may be filled with sponge rubber or may be pressurised by inflation with an air needle. 

A tyre which is composed of solid rubber bonded to a suitable wheel and without an internal air space, as in the pneumatic tyre or an internal cavity as in the semi-solid tyre. The main uses of solid tyres are on forklift trucks and armoured fighting vehicles (tanks). 

There are exceptions to this rule as ammonium bicarbonate is successfully used in eclairs and other choux pastry products. It seems that the thin walls, large internal cavity and high baking temperature combined allow the ammonia to be driven off. 

The CoA binding tunnel provides access to the internal cavity. B. Molecular surface representation of the CHS-CoA complex oriented as shown in (A). In the -bottom panel, the two CHS monomers are separated and rotated slightly to highlight the flat dimerization interface along with the methionine side chain and dyad related hole in the backside of the CHS active site. 

Mesenchymal tissue is immature, unspecialized tissue, found in the early embryo of animals, whereas epithelial cells are parenchymal cells that line an internal cavity or tube. 

Each catenane consists of two identical, interlocked 26-membered rings with a relatively small internal cavity (with dimensions of 4x6 A). This interlocked species was the first amide-catenane to be structurally characterised (although Hunter s and Vogtle s catenanes were reported earlier). The structure supported the proposal that the driving force for catenane formation is hydrogen bonding between the newly formed 1,3-diamine units and carbonyl groups of the acid... 

Scheme 1 summarizes four different approaches used to characterize dendrimer structures by photophysical and photochemical probes 1. Non-covalent, inter-molecularly bound interior probes - to study the internal cavities and the encapsulation abilities of dendrimers. 2. Non-covalent, intermolecularly bound surface probes - to study surface characteristics of dendrimers. 3. Covalently linked probes on dendrimer surfaces - to study the molecular dynamics of dendrimers. 4. Covalently linked probes at the dendrimer central core - to study the site isolation of the core moiety and define the hydrodynamic volume of dendrimers by the concentric dendrimer shells. Critical literature in these four categories will be described using representative examples. 

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