Interaction core-shell

The other type of nanoparticulate structure and fabrication morphology is the core-shell and associated hollow spheres. In this instance, a spherical nanostructure is established by polymerization onto a preformed nanoparticle. Different template materials have been used for fabrication. For chemical-sensing applications, the two most widely used have been silica and polystyrene, as highly monodisperse nanoparticles of these materials can be reliably synthesized. In addition, their surface chemistry can be modified to achieve different monomer interactions. Core-shell structures could be formed from the... 

Figure 2.8 Shell model of ionic polarizability (a) unpolarized ion (no displacement of shell) (b) polarized (displaced shell) (c) interactions 1, core-core 2, shell-shell 3, core-shell.

The single pair interactions are now each replaced by four pair interactions core ion /-core ion j, shell ion /-shell ion j, shell ion /-core ion j, and core ion /-shell ion j (Fig. 2.8c). Equation (2.17) now becomes... 

A scaled-up version of this central template-concentric sphere surface assembly approach has been demonstrated for the growth of multi-layer core-shell nano- and microparticles, based upon the repeated layer-by-layer deposition of linear polymers and silica nanoparticles onto a colloidal particle template (Figure 6.8) [60]. In this case, the regioselective chemistry occurs via electrostatic interactions, as opposed to the covalent bond formation of most of the examples in this chapter. The central colloidal seed particle dictates the final particle... 

Fig. 7 The interaction and coupling modes of dye molecules and metal in a core-shell structure for fluorescence enhancement...

Aliev, F.G. Correa Duarte, M.A. Mamedov, A. Ostrander, J.W. Giersig, M. Liz-Marjan, L.M. Kotov, N.A. (1999) Layer-by-layer assembly of core shell magnetite nanoparticles Effect of silica coating on interparticle interactions and magnetic properties. Adv. Mater. 11 1006-1010... 

Let us consider approximations in accounting for the Breit interaction, that we made when outer core and valence electrons are included in GRECP calculations with Coulomb two-electron interactions, but inner core electrons are absorbed into the GRECP. When both electrons belong to the inner core shells, the Breit effect is of the same order as the Coulomb interaction between them. Though Bff does not contribute to differential (valence) properties directly, it can lead to essential relaxation of both core and valence shells. This relaxation is taken into account when the Breit interaction is treated by self-consistent way in the framework of the HEDB method [33, 34]. 

Due to small relaxation of outer core shells in most processes of interest, these shells can be also considered as frozen when analyzing the Breit contributions and the Bed and Bev terms can be taken into account similarly to the Bfc and Bf ones. The error of this approximation will be additionally suppressed by relative weakness of the Breit interaction with the outer core electrons as compared to the inner core ones. We note... 

Different nuclear models and contributions of the Breit interaction between valence, inner and outer core shells of uranium, plutonium and superheavy elements El 12, E113, and El 14 are considered in the framework of allelectron four-component and (G)RECP methods. It is concluded on the basis of the performed calculations and theoretical analysis that the Breit contributions with inner core shells must be taken into account in calculations of actinide and SHE compounds with chemical accuracy whereas those between valence and outer core shells can be omitted. 

A similar increase in the values for the hyperfine constants and parameters of the P,T-odd interactions when the correlations with the core shells (primarily, 5s, bp) are taken into account is also observed for the BaF molecule [93], as one can see in Table 3. Of course, the corrections from the 4/-electron excitations are not required for this molecule. The enhancement factor for the P,T-odd effects in BaF is three times smaller than in YbF mainly because of the smaller nuclear charge of Ba. 

As with normal hydrocarbon-based surfactants, polymeric micelles have a core-shell structure in aqueous systems (Jones and Leroux, 1999). The shell is responsible for micelle stabilization and interactions with plasma proteins and cell membranes. It usually consists of chains of hydrophilic nonbiodegradable, biocompatible polymers such as PEO. The biodistribution of the carrier is mainly dictated by the nature of the hydrophilic shell (Yokoyama, 1998). PEO forms a dense brush around the micelle core preventing interaction between the micelle and proteins, for example, opsonins, which promote rapid circulatory clearance by the mononuclear phagocyte system (MPS) (Papisov, 1995). Other polymers such as pdty(sopropylacrylamide) (PNIPA) (Cammas etal., 1997 Chung etal., 1999) and poly(alkylacrylicacid) (Chen etal., 1995 Kwon and Kataoka, 1995 Kohorietal., 1998) can impart additional temperature or pH-sensitivity to the micelles, and may eventually be used to confer bioadhesive properties (Inoue et al., 1998). 

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