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Janus structure

Possible shapes and forms of Janus particle (a) spherical Janus particle (b) and (c) two types of Janus cylinder (d)and (e) two types of Janus disks [93], [Pg.401]

Schematic representation of JPs and their adsorption at the blend interface of a PS/PMMA blend [92]. [Pg.401]

The SEM and TEM images shown in Eigure 17.16 give an overview of the development of the domain sizes of the dispersed phase. The SEM images (PS/PMMA=6/4) are shown at the same magnification in [Pg.402]

SEM images obtained for biends at a PS/PMMA ratio of 6/4 (top row). Non-stained TEM images obtained for biends at a PS/PMMA ratio of 8/2 (center and iower row). Theamount of compatibiiizer is indicated in each image [92]. [Pg.402]

TEM images obtained for (a) 10wt% JP in a 8/2 PS/PMMA biend and for (b) 20wt% JP in a 6/4 PS/PMMA blend (c) TEM of Janus particles blended into a PS matrix (2wt% of Janus particles). The arrows highlight Janus particles [92]. [Pg.403]


It has been reported that a series of polymer blends in aqueous solution could self-assemble into phase-separated structures such as core—shell or Janus-type polymer nanoparticles (Motoyoshi et al, 2010). Moreover, Guo et al (2013) performed DPD simulations to systematically investigate the effects of hydrophobicity and compatibhity, and both play important roles in controlling the self-assembled structures of polymer blends in aqueous solution. Most importantly, the temperature-dependent core-shell to Janus structure transition of thermosensitive polymer blends was observed by DPD simulations for the first time. [Pg.142]

A Janus separator was proposed because Janus structures can offer asymmetry and realize the emergence of properties inconceivable for homogeneous or S5mnmetric structures (39). The name Janus was derived from the Roman god Janus. [Pg.63]

A gene encoding this sequence was synthesized and the corresponding protein, called Janus, was expressed, purified, and characterized. The atomic structure of this protein has not been determined at the time of writing but circular dichroic and NMR spectra show very clear differences from B1 and equally clear similarities to Rop. The protein is a dimer in solution like Rop and thermodynamic data indicate that it is a stably folded protein and not a molten globule fold like several other designed proteins. [Pg.370]

These results indicate that is it possible to change the fold of a protein by changing a restricted set of residues. They also confirm the validity of the rules for stability of helical folds that have been obtained by analysis of experimentally determined protein structures. One obvious impliction of this work is that it might be possible, by just changing a few residues in Janus, to design a mutant that flip-flops between a helical and p sheet structures. Such a polypeptide would be a very interesting model system for prions and other amyloid proteins. [Pg.370]

Figure 8.3 Schematic representation of the general domain structure of a STAT protein. A conserved ( C or con ) domain is located at the N-terminus, followed by the DNA-binding domain (D). Y represents a short se-guence that contains the tyrosine residue phosphorylated by the Janus kinase. The carboxy terminus domain (Tr) represents a transcriptional activation domain... Figure 8.3 Schematic representation of the general domain structure of a STAT protein. A conserved ( C or con ) domain is located at the N-terminus, followed by the DNA-binding domain (D). Y represents a short se-guence that contains the tyrosine residue phosphorylated by the Janus kinase. The carboxy terminus domain (Tr) represents a transcriptional activation domain...
Recent progress in novel micellar structures, including micelles containing exotic blocks such as natural or synthetic polypeptides and metal-containing segments, micelles from ABC triblock copolymers, Janus micelles and other noncentrosymmetric micelles, micelles based on interpolyelectrolyte or other noncovalent complexes, and metallosupramolecular micelles, will be discussed in Sect. 7. [Pg.81]

It should, however, be mentioned that the transfer of a bulk-organized system into solution can lead to very interesting structures, as will be demonstrated in Sect. 7.3 in the case of Janus micelles [33]. In this case, a micellar structure is preformed in the bulk, its core is stabilized by cross-linking, and... [Pg.85]

Uckun, F.M., Thoen, J., Chen, H., Sudbeck, E., Mao, C., Malaviya, R., Liu, X.-P. and Chen, C.-L. (2002) CYP1A-mediated metabolism of the janus kinase-3 inhibitor 4-(4 -hydroxyphenyl)-amino-6,7-dimethoxyquinazoline structural basis for inactivation by regioselective o-demethylation. Drug Metabolism and Disposition The Biological Fate of Chemicals, 30 (1), 74—85. [Pg.265]

Another family of protein kinases involved in signal transduction via cytokines includes the Janus kinases (Jak kinases). At least four different Jak kinases are known in mammals (Jakl, Jak2, Jak3 and Jak4). A characteristic feature of the structure of Jak kinases is the occurrence of two tyrosine kinase domains (Fig. 11.5). However, only... [Pg.364]

Fig. 11.5. Domain structure of the Jak kinases. JHl is the catalytic tyrosine kinase domain. JH2 shows similarity to a tyrosine kinase domain. The domains A—E are homologous elements of the Jak kinase family. JH Janus kinase homology region. Fig. 11.5. Domain structure of the Jak kinases. JHl is the catalytic tyrosine kinase domain. JH2 shows similarity to a tyrosine kinase domain. The domains A—E are homologous elements of the Jak kinase family. JH Janus kinase homology region.
Cytokines all function using a group of transmembrane receptors embedded in the plasma membranes of target cells. The receptors have no tyrosine kinase activity but associate with and activate kinases known as Janus kinases (JAKs). These kinases phosphory-late tyrosine side chains in their receptors, and the phosphorylated receptors activate transcription factors of the STAT (signal transducer-activators of transcription) group.186-195 The specificity of cytokine action results from a combination of receptor recognition and recognition of the various STAT molecules by different JAKs.111 Cytokines have a variety of structures. Many are helix bundles or have (3 sheet structures (Fig. 30-6). [Pg.1847]

Fig. 47 (a) Examples of polyphilic molecules with star shaped molecular topologies and (b) their mesophase morphologies [295]. (c) Janus-type porphyrin 177 [277] and (d) modes of self assembly of the completely RF-substituted porphyrin 156 left, for structure see Fig. 42, Colortho G -29 °C Colortho199 °C Iso) and the partly fluorinated porphyrin 177 right, ColTeJp2mg, Cr -22 °C Co n,Jp2mg 163 °C Iso) Colortho = orthorhombic columnar 3D phases (b) Reproduced with permission [295], copyright 2008, The Royal Society of Chemistry (RSC) (d) reproduced with permission [277], copyright 2011, American Chemical Society (ACS)... Fig. 47 (a) Examples of polyphilic molecules with star shaped molecular topologies and (b) their mesophase morphologies [295]. (c) Janus-type porphyrin 177 [277] and (d) modes of self assembly of the completely RF-substituted porphyrin 156 left, for structure see Fig. 42, Colortho G -29 °C Colortho199 °C Iso) and the partly fluorinated porphyrin 177 right, ColTeJp2mg, Cr -22 °C Co n,Jp2mg 163 °C Iso) Colortho = orthorhombic columnar 3D phases (b) Reproduced with permission [295], copyright 2008, The Royal Society of Chemistry (RSC) (d) reproduced with permission [277], copyright 2011, American Chemical Society (ACS)...
Fig. 48 (a) Janus-type discotic hydrogen bonded aggregate 178 and (b) possible hexagonal superlattice LC phase (cross section through the structure viewed along the column axis, gray = regions of the RF-chains) [300]... [Pg.63]

Fig. 49 (a) Examples of Janus-type bis-dendrons and (b) model of the self-assembly in a core-shell columnar LC structure [154]. Reproduced with permission [154, Bioinspired supra-molecular liquid crystals, Fig. 3], copyright 2006, The Royal Society... [Pg.64]

Permethylated tosylated a-cyclodextrin was coupled with aminohydroxyazo-benzene. The product was dimerized to Janus [2]pseudorotaxane, which in turn was bis-azo coupled with 2-naphthol-3,6-disulfonic acid. The product undergoes selfassociation as shown in Figure 14 [44], Note that the final product has o-quinone hydrazone structure. [Pg.211]

Abstract Polyelectrolyte block copolymers form micelles and vesicles in aqueous solutions. Micelle formation and micellar structure depends on various parameters like block lengths, salt concentration, pH, and solvent quality. The synthesis and properties of more complicated block and micellar architectures such as triblock- and graft copolymers, Janus micelles, and core-shell cylinder brushes are reviewed as well. Investigations reveal details of the interactions of polyelectrolyte layers and electro-steric stabilization forces. [Pg.173]

Janus micelles are non-centrosymmetric, surface-compartmentalized nanoparticles, in which a cross-linked core is surrounded by two different corona hemispheres. Their intrinsic amphiphilicity leads to the collapse of one hemisphere in a selective solvent, followed by self-assembly into higher ordered superstructures. Recently, the synthesis of such structures was achieved by crosslinking of the center block of ABC triblock copolymers in the bulk state, using a morphology where the B block forms spheres between lamellae of the A and C blocks [95, 96]. In solution, Janus micelles with polystyrene (PS) and poly(methyl methacrylate) (PMMA) half-coronas around a crosslinked polybutadiene (PB) core aggregate to larger entities with a sharp size distribution, which can be considered as supermicelles (Fig. 20). They coexist with single Janus micelles (unimers) both in THF solution and on silicon and water surfaces [95, 97]. [Pg.197]

Fig. 21 Synthesis and tentative structure of amphiphilic Janus micelles and their supermicelles. Reprinted with permission from ref [99]. Copyright (2003) American Chemical Society... Fig. 21 Synthesis and tentative structure of amphiphilic Janus micelles and their supermicelles. Reprinted with permission from ref [99]. Copyright (2003) American Chemical Society...
Finally, it is shown that non-linear amphiphilic structures show different aggregation behavior as compared to block copolymers. Graft copolymers with non-polar backbone polyelectrolyte side chains have a smaller tendency to form micelles than their block copolymer analogs which is attributed to the more facile stabilization of unimers by the sidechains. In contrast, unimolecular micelles are the only possibility for core-shell nanoparticles. Janus micelles, on the other hand, form unique non-centrosymmetrical micelles that have a strong tendency to form centrosymmetrical supermicelles. [Pg.207]


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See also in sourсe #XX -- [ Pg.400 , Pg.401 , Pg.402 ]




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