Types of core material

Miniemulsion is a special class of emulsion that is stabilized against coalescence by a surfactant and Ostwald ripening by an osmotic pressure agent, or costabilizer. Compared with conventional emulsion polymerization process, the miniemulsion polymerization process allows all types of monomers to be used in the formation of nanoparticles or nanocapsules, including those not miscible with the continuous phase. Each miniemulsion droplet can indeed be treated as a nanoreactor, and the colloidal stability of the miniemulsion ensures a perfect copy from the droplets to the final product. The versatility of polymerization process makes it possible to prepare nanocapsules with various types of core materials, such as hydrophilic or hydrophobic, liquid or solid, organic or inorganic materials. Different techniques can be used to initiate the capsule wall formation, such as radical, ionic polymerization, polyaddition, polycondensation, or phase separation from preformed polymers. 

On-chip waveguides can be fabricated from different types of core materials. Traditionally glass has been a popular choice, but recently polymers have gained popularity due to lower costs and excellent transmittance characteristics [4]. Furthermore, polymeric waveguides can now be easily integrated with microfluidic devices, which are now commonly made in polymers. 

Although a variety of alternative microencapsulation techniques is available (for details of sol-gel techniques, see Chapter 8), no single method is suitable for encapsulating different types of core material. Ultimately, the best method will depend upon the type of core material, the required particle size, the permeability of the shell wall, and the different properties of the microcapsule, and consequently the process must be custom-tailored in order to provide a satisfactory outcome. An overview of the size of microcapsules obtained by different techniques is provided in Table 1.2. 

Many types of core material are available, but they are broadly divisible into two types according to application, namely aqueous Kquid cores and oily liquid c ores, the latter being used widely in medicine, food and other indushial applications. 

On-chip waveguides can be fabricated from different types of core materials. Traditionally glass has been a popular choice, but recently polymers have gained popularity... 

Irons largely or entirely consist of nickel-iron alloys. At least some of them are probably the remains of core materials of the planetesimals that once existed in the solar system (Dalrymple, 1991, 274). Based on their chemistry, irons are subdivided into several types, which are usually identified with Roman numerals and letters (IAB, IC, IVA, etc.) Krot, Keil and Goodrich (2004) discusses a common classification system for irons. 

Plywood construction refers to the composition of the inner plies or layers. The faces are usually always veneer but the cores may consist of four different types of wood materials all inner plies of (1) wood veneer ... 

Therefore, local dissolution and recrystallization seem to play an important role in the gas uptake mechanism in these type of sensor materials. The coordination of SO2 to the platinum center (and the reverse reaction) is therefore likely to take place in temporarily and very locally formed solutes in the crystalline material, whereas the overall material remains crystalline. The full reversibility of the solid-state reaction was, furthermore, demonstrated with time-resolved solid-state infrared spectroscopy (observation at the metal-bound SO2 vibration, vs= 1072 cm-1), even after several repeated cycles. Exposure of crystalline samples of 26 alternat-ingly to an atmosphere of SO2 and air did show no loss in signal intensities, e.g. due to the formation of amorphous powder. The release of SO2 from a crystal of 27 was also observed using optical cross-polarization microscopy. A colourless zone (indicative of 26) is growing from the periphery of the crystal whereas the orange colour (indicative for 27) in the core of the crystal diminishes (see Figure 9). 

In general, these methods are used for the production of nanocrystalline powders which may be further compacted via techniques such as hot-pressing [157, 158] or magnetic pulsed compaction [159, 160]. In addition, other types of nanoionic material maybe prepared, such as nanometer-thin films, using techniques including molecular beam epitaxy [161], pulsed laser deposition [162] or spin-coating methods [163]. Novel structures, such as core-shell [164—166] and multi-layered [167, 168] (so-called onion structures) materials, may also be produced in this way. 

FIGURE 8.10 Effect of EA network type and RH during aging on of core material (carotenoid compound diffused from the composite film into the bulk oil phase). (From Wongsasulak, S. et al.. Food Res. Int., 40, 249, 2007. With permission.)... 

Use of an appropriate cladding material will permit a fiber s core to etch faster than its clad. When such an etch is carried out on a fiber-optic bundle, the result is a bundle tip with one well per fiber. Remarkably, when the tip is brought into contact with a suspension of well-sized beads, self-assembly occurs to yield a bead-filled array. While this bulk self-assembly process is not really akin to the molecular assembly processes of current academic interest, the result is perhaps equally striking. The atomic force micrographs (AMF) shown in Fig. 7 reveal an etched bundle tip with 4-pm wells being filled by 3.5-pm polystyrene beads. Experience reveals that many types of bead material will self-assemble into etched bundle tips. 

The FFTF refueling system (Cabell, 1980 FFTF, 1983) includes facilities for the receipt, conditioning, storage, installation in and removal from the core of all core components (driver fuel assemblies, control assemblies) and test assemblies that are routinely removable. The reactor refueling system handled three types of core assemblies 12-ft assemblies such as driver fuel 40-ft assemblies such as fuels open test assemblies and 40-ft assemblies such as materials open test assemblies. 

This type of core system was investigated because strong core-core attractions and a low ionisation potential were expected. Accordingly, and similarly to phthalocyanines, such materials may be useful in electronic and photoelectronic applications as electron carriers. 

Summary of major design characteristics types of fuel, fuel enrichment, types of coolant/moderator, types of structural materials, core type/characteristic dimensions, vessel type/characteristic dimensions, cycle type (direct/indirect), number of circuits... 

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