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Mohammadi Y.,Iran National Petrochemical Company | Ahmadi M.,Amirkabir University of Technology | Saeb M.R.,Iran Institute for Color Science and Technology | Khorasani M.M.,Iran National Petrochemical Company | And 5 more authors.
Macromolecules | Year: 2014

We introduce a theoretical model based upon the kinetic Monte Carlo (KMC) simulation approach capable of quantifying chain shuttling copolymerization (CSP) of ethylene and 1-octene in a semibatch operation. To make a deeper understanding of kinetics and evolution of microstructure, the reversible transfer reaction is first investigated by applying each of the individual catalysts to the reaction media, and the competences and shortcomings of a qualified set of CSP catalysts are discussed based on coordinative chain transfer copolymerization (CCTP) requirements. A detailed simulation study is also provided, which reflects and compares the contributions of chain transfer reversibility and other chain breaking reactions in controlling distribution fashion of molecular weight and chemical composition. The developed computer code is executed to capture developments in dead chain concentration and time-driven composition drift during CCTP. Also, the effect of chain shuttling agent (CSA) on the copolymerization kinetics is theoretically studied by simultaneous activation of both catalysts. In this way, it is attempted to make control over comonomer incorporation in the course of copolymerization. The molecular-level criteria reflecting copolymer properties, i.e., ethylene sequence length distribution and longest ethylene sequence length, as the signature of CSA performance, are virtually simulated in the presence and absence of hydrogen to capture an image on gradient copolymers in CCTP and blocks with gradually changing composition in CSP. © 2014 American Chemical Society.

Ghavaminejad A.,Chonbuk National University | Sasikala A.R.K.,Chonbuk National University | Unnithan A.R.,Chonbuk National University | Thomas R.G.,Chonnam National University | And 7 more authors.
Advanced Functional Materials | Year: 2015

A method for the versatile synthesis of novel, mussel-inspired, electrospun nanofibers with catechol moieties is reported. These mussel-inspired nanofibers are used to bind iron oxide nanoparticles (IONPs) and the borate-containing anticancer drug Bortezomib (BTZ) through a catechol metal binding mechanism adapted from nature. These smart nanofibers exhibit a unique conjugation of Bortezomib to their 1, 2-benzenediol (catechol) moieties for enabling a pH-dependent drug delivery towards the cancer cells and the IONPs via strong coordination bonds for exploiting the repeated application of hyperthermia. Thus the synergistic anticancer effect of these mussel-inspired magnetic nanofibers were tested in vitro for the repeated application of hyperthermia along with the chemotherapy and found that the drug-bound catecholic magnetic nanofibers exhibited excellent therapeutic efficacy for potential anticancer treatment. Drug-loaded magnetic nanofibers are designed for a synergistic anticancer treatment that combines hyperthermia treatment and chemotherapy. A mussel-inspired binding is used to incorporate iron oxide nanoparticles (IONPs) and the drug onto the nanofibers. The smart nanofibers are capable of pH-dependent drug delivery to cancer cells, and their IONPs enable multiple cycles of hyperthermia therapy with the application of an alternating magnetic field (AMF). © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Guo S.-F.,Southwest University | Wang J.-F.,Chongqing University | Zhang H.-J.,Chongqing University | Xie S.-H.,Shenzhen Key Laboratory of Special Functional Materials | Xie S.-H.,Shenzhen University
Transactions of Nonferrous Metals Society of China (English Edition) | Year: 2012

The room temperature compressive plasticity of Fe 75Mo 5P 10C 8.3B 1.7 bulk metallic glass (BMG) was improved from 0.5% to 1.8% by increasing the sample diameter from 1.5 mm to 2.0 mm. With increasing the sample diameter to 2.0 mm, a heterogeneous microstructure with in-situ formed α-Fe dendrite sparsely distributed in the amorphous matrix can be attained. This heterogeneous microstructure is conceived to be highly responsible for the enhanced global plasticity in this marginal Fe-based BMG. © 2012 The Nonferrous Metals Society of China.

Hu Q.,Northwestern Polytechnical University | Zeng X.-R.,Shenzhen University | Zeng X.-R.,Shenzhen Key Laboratory of Special Functional Materials | Fu M.W.,Hong Kong Polytechnic University
Journal of Applied Physics | Year: 2012

The free volume change ΔV f(T) of bulk metallic glasses (BMGs) relative to a hypothesized amorphous reference state was measured using the thermal dilatation method. The characteristic free volume change, i.e., the free volume released in structural relaxation ΔV f-sr, was identified quantitatively from the ΔV f(T) curve. For a Fe-based BMG, it was found that ΔV f-sr increases with decreases in the sample diameter and heating rate. ΔV f-sr measured under the same sample diameter and heating rate conditions allowed the convenient comparison of different BMGs. The comparison revealed that the glass-forming ability (GFA) enhancement of each of two Pd-, Mg-, Cu-, Zr-, Ti-, and Fe-based BMGs can be sensitively reflected in the decrease in ΔV f-sr and the narrowing of the difference between the peak temperature of the thermal expansion coefficient and the end temperature of the glass transition process. In addition, for these twelve typical BMGs, there is a good linear relationship between ΔV f-sr and Log D c 2 or Log D c, where D c is the critical diameter. ΔV f-sr is thus sensitive to and has a close correlation with GFA. Furthermore, the ΔV f-sr measurement results are in good agreement with the free volume change measured with the specific heat capacity, room temperature density, and positron annihilation lifetime methods. In the study of the relationship between the structure and properties of BMGs, ΔV f-sr thus plays an important role given its comparability and convenience. © 2012 American Institute of Physics.

Hu Q.,Northwestern Polytechnical University | Zeng X.-R.,Shenzhen University | Zeng X.-R.,Shenzhen Key Laboratory of Special Functional Materials | Fu M.-W.,Hong Kong Polytechnic University
Applied Physics Letters | Year: 2010

This paper reports the observation of the clear Invar effects of (Fe71.2 B24 Y4.8) 96 Nb4 bulk metallic glass. The Invar effects of (Fe71.2 B24 Y4.8) 96 Nb4 alloys in different structural states are also investigated in situ through cyclic thermal dilation tests at different cyclic temperatures. The results show that these Invar effects are strengthened in the relaxation amorphous state, weakened in the nanocrystalline state, and absent in the complete crystalline state. X-ray diffraction and Mössbauer spectroscopy demonstrate that the structural influences on Invar effects can be explained by the different local atomic arrangements around Fe atoms in different structural states. © 2010 American Institute of Physics.

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