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Morphology Transformation of a Polymeric Micelle Induced by Two Encapsulated Particles

100%
Zhang Q., Xiang X.
Acta Physica Polonica A
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2014
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vol. 126
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issue 6
1338-1342
EN
We begin with a pair of spherical particles encapsulated in a micelle and solve the problem within the self-consistent field theory to investigate the morphology transformation of the micelle induced by two nano-particles. The micelles are based on amphiphilic diblock copolymer AB in homopolymer A solvents. The nano-particles are simple models of proteins or colloids. We predict different micelle structures, and relate these morphologies to particle sizes, distances between two particles, and chemical potentials of the amphiphile molecules. There are found complex structures of the micelle induced by the twin particles: many reverse micelles only with even numbers or only one micelle attached at one of the two particles. These results are of immediate interests to the interactions of micelles and particles, as well as to the transitions between vesicles and micelles.
2
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Interaction between Polymer Brush and Nanoparticle: Brownian Dynamics Investigation

100%
Zhang Q., Xiang X.
Acta Physica Polonica A
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2013
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vol. 123
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issue 4
642-646
EN
We use Brownian dynamics simulations to study the adsorption behavior of a nanosized particle on polymer brushes. The adsorption process, the dynamic behavior of the nanoparticle in brush, the penetration depth, and the diffusion coefficient of the nanoparticle in different depths of the brush are all investigated for different grafting densities. We provide an area density Γp, which is the area average of the monomer number above the embedded nanoparticle in brush. We find that this area density explains well qualitatively the experimental phenomenon that the nanoparticles exhibit a maximum in the adsorbed amount as a function of the grafting density of brush.
3
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Experimental Evidence for Jahn-Teller Transition in a Fe(II)Fe(III) Bimetallic Oxalate

81%
Tang G., He Y., Xu F., Zhang Q.
Acta Physica Polonica A
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2013
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vol. 123
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issue 1
118-120
EN
Bimetallic oxalate {[N-(n-C_4H_9)_4][FeFe(C_2O_4)_3]}_{n} has been investigated by the Mössbauer spectroscopy. The Mössbauer studies confirm that high-spin Fe(III) (S=5/2) and Fe(II) (S=2) ions are present in the compound. These spectra above 60 K consist of three quadrupole doublets, indicating that there are three different Fe sites in the material. The Mössbauer results reveal that spontaneous magnetization of Fe(II) sublattices increases more steeply than that of Fe(III) sublattices as the temperature decreases from T_{C}. Great increase of quadrupole splitting at 50 K provides compelling evidence for the predicted Jahn-Teller transition.
4

Diminished expression of the type II receptor for TGFbeta (TGFbetaRII) in T lymphocytes from patients with Sezary syndrome is not due to mutations in the receptor?s Poly-A tract: limitations of the standard RT-PCR in cDNA sequence analysis of homopo

52%
Zhang Q., Capocasale R. J., Fox F. E., Bedian V., Vonderheid E. C., Rook A., Moore J. S., Nowell P. C., Haines D. S., Wasik M. A.
Archivum Immunologiae et Therapiae Experimentalis
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2002
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vol. 50
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issue 6
419-427
EN
Peripheral blood lymphocytes from patients with Sezary syndrome (SzS) frequently demonstrate decreased surface expression of transforming growth factor beta receptor II (TGFbetaRII). The mechanism of this low TGFbetaRII expression remains unknown. Because mutations within the poly-A tract of the TGFbetaRII sequence (nucleotides 709-718) were shown to result in diminished TGFbetaRII expression in other types of malignant tumors, we examined the sequence of the TGFbetaRII poly-A tract in two SzS-derived cell lines and in peripheral blood SzS cells from 17 SzS patients and 4 control, healthy individuals using DNA sequencing and single-stranded conformation polymorphism (SSCP) analysis. A standard bidirectional, automated sequence analysis of the RT-PCR-generated cDNA TGFbetaRII fragment showed a heterogenous population of the normal length, 10-, with admixed, shortened, 9-base poly-A stretches. Surprisingly, this mixture was present not only in the cells from 5 SzS patients and 2 SzS cell lines, but also in cells from 2 healthy control individuals. Importantly, the proportion of the shortened, 9-base fragments was markedly reduced or practically eliminated when the procedure was modified by usage of high-fidelity DNA polymerase, labeled primers and/or cloned RT-PCR products, which indicates that the presence of the shortened, 9-base fragments represented a procedural phenomenon rather than a true deletional mutation within an allele of the TGFbetaRII gene. Accordingly, SSCP analysis of genomic DNA did not reveal any mutations within the poly-A tract-containing region. These results indicate that a mechanism different from mutations in the polyadenine tract underlies the diminished TGFbetaRII expression in SzS cells and that the results of an unmodified, direct sequence analysis of homopolymeric base streaches in RT-PCR-derived cDNA should be interpreted with caution.
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