Jie Zhang

Sichuan University, Hua-yang, Sichuan, China

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Publications (32)50.57 Total impact

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    ABSTRACT: In the present study, using chondroitin sulfate as morphology-directing matrix, hydroxyapatite–chondroitin sulfate hybrid mesoporous microrods were prepared successfully through a facile one-pot method under mild conditions. From the results, the antitumor drug doxorubicin hydrochloride (DOX·HCl) could be loaded into the as-prepared microrods efficiently owing to the large specific surface area and the presence of the mesopores. In addition, the loaded DOX·HCl could be controlled released with pH-dependent and sustained features. These suggest that the hybrid mesoporous microrods prepared in this study might be used as the potential targeted drug delivery carrier to treat the human tumors clinically with good specificity and long duration.
    Materials Letters 06/2014; 125:111–115. · 2.27 Impact Factor
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    ABSTRACT: This study investigates the influence of length scale effects (micro- and macro-injection molded parts) and mold temperature on the epitaxial growth and morphological characteristics in injection-molded bars of isotactic polypropylene (iPP)/high-density polyethylene (HDPE) blends. After preparing the blends with an iPP content of 70 wt% via melt extrusion, the injection-molded bars were formed using both micro and conventional injection molding. Samples were subsequently prepared from the moulded components to allow investigation of the internal morphology using wide-angle X-ray diffraction (WAXD), differential scanning calorimetry (DSC), scanning electron microscopy (SEM) and polarized light microscopy (PLM). The results indicated that the matching of micro scale and appropriate mold temperature was most favorable for epitaxial crystallization. The micro-parts had a large fraction of shear layer compared with macro-parts. The SEM observations showed that the shear layer of the former consisted of a highly oriented shish-kebab structure. Moreover, the effects of different methods of injection molding on the morphological characteristics of the micro-parts and macro-parts in different layers were elucidated in detail using PLM and SEM.
    Polymer Testing 01/2014; · 1.65 Impact Factor
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    ABSTRACT: In optical printed Chinese character recognition (OPCCR), many classifiers have been proposed for the recognition. Among the classifiers, support vector machine (SVM) might be the best classifier. However, SVM is a classifier for two classes. When it is used for multi-classes in OPCCR, its computation is time-consuming. Thus, we propose a neighbor classes based SVM (NC-SVM) to reduce the computation consumption of SVM. Experiments of NC-SVM classification for OPCCR have been done. The results of the experiments have shown that the NC-SVM we proposed can effectively reduce the computation time in OPCCR.
    PLoS ONE 01/2013; 8(3):e57928. · 3.53 Impact Factor
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    ABSTRACT: Herein, mesoporous calcite/chondroitin sulfate hybrid microrods are prepared through a one-pot method. Biological assays indicate that the microrods might be used as good active targeted drug delivery carriers to treat tumor tissues with high specificity and low toxic side effects.
    Chemical Communications 09/2012; 48(86):10636-8. · 6.38 Impact Factor
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    ABSTRACT: Herein, through tuning the surface energy difference of the major crystal planes by alloying, hollow palladium/copper alloyed nanostructures are successfully prepared through a one-pot template-free strategy. Compared with the solid PdCu alloyed nanoparticles, the hollow PdCu alloyed nanostructures exhibit the increased accessible electrochemical active surface area and the enhanced electrocatalytic activity for formic acid oxidation. It is concluded that the as-prepared hollow PdCu alloyed nanostructures would be a potential candidate as an anode electrocatalyst in direct formic acid fuel cell. More importantly, the strategy developed in this study might be expanded to fabricate other metal alloyed hollow nanostructures.
    ACS Applied Materials & Interfaces 08/2012; 4(9):4461-4. · 5.90 Impact Factor
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    ABSTRACT: In optical printed Chinese character recognition (OPCCR), support vector machine (SVM) is thought to be a good classifier. However, the recognition rate of SVM depends on the features extracted and the time consumption of it is large. For this reason, we propose statistic features (SF) and local nearest neighbor SVM (LNN-SVM) to promote the recognition rate and to reduce the computational time of SVM. Experiments have been done and the results showed that SF and LNN-SVM can promote the recognition rate and reduce the computational time in OPCCR.
    01/2012;
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    ABSTRACT: Micro-injection molding is attracting much attention nowadays. Characterization of the morphological distribution in parts prepared by micro-injection molding is thus of growing importance. The morphological features of micro-parts may strongly differ from those of the macro-parts prepared by conventional injection molding, resulting in specific physical properties. In the present study, β-nucleated isotactic polypropylene micro-parts (μPPB) with 200 μm thickness, as well as macro-parts (PPB) with 2000 μm thickness, were prepared. Polarized light microscopy (PLM), scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and wide-angle X-ray diffraction (WAXD) were used to investigate their morphological features. The results show that the morphology distribution in μPPB had many differences from that of the PPB. The 1D WAXD and DSC analysis showed similar results; the degree of crystallinity of the μPPB was higher than that of the PPB. However, the content of β-crystals of μPPB was lower than that of the PPB. This can be explained by the restraining effect for the formation of β-crystals in β-nucleated iPP under the strong shear field. The through-the thickness-morphology of both μPPB and PPB exhibited a ‘skin-core’ structure from PLM observations, but the former had a large fraction of shear layer in comparison to the latter implied. The SEM observations showed that the shear layer of μPPB consisted of a highly oriented shish-kebab structure while that of the core layer consisted of deformed spherulites structure. The 2D WAXD pattern of the core layer of PPB, showing full Debye rings, indicated an overall random orientation of the iPP chains, while the arcing indicated a pronounced orientation in the shear layer. The more pronounced arcing of the μPPB indicated a more pronounced orientation.
    Journal of Macromolecular Science Part B 01/2012; · 0.63 Impact Factor
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    ABSTRACT: To compare the difference of morphological evolution of HDPE micropart and macropart, micropart with 200 μm thickness and macropart with 2000 μm thickness were prepared. The PLM images of micropart and macropart exhibited a similar “skin–core” structure, but the micropart showed a much larger fraction of orientation layer. The SEM observation of core layer of micropart featured an unoriented lamellae structure and shear layer of micropart showed a highly oriented shish‐kebab structure. The 2D‐WAXD patterns of shear layer of macropart indicated twisted oriented shish‐kebab (KM‐I) structures, however that of micropart indicated untwisted oriented shish‐kebab (KM‐II) structures which was firstly found in microinjection molding. The diffraction pattern of the micropart exhibited stronger azimuthal dependence than the shear layer of macropart, indicating the most pronounced orientation of HDPE chains within lamellae. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
    Journal of Applied Polymer Science 01/2012; 126(2). · 1.40 Impact Factor
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    ABSTRACT: Microwave heating technology has numerous advantages compared with the traditional heating methods and has been widely used to process materials. However, most thermoplastics do not possess a sufficiently high dielectric property to be heated by microwaves. In this study, carbon black (CB) was utilized as the microwave absorber to improve the microwave heatability of isotactic polypropylene (iPP). Effects of CB contents on the microwave heatability of iPP/CB composites were studied. The temperature of iPP/CB composites with relatively low CB content (5% and 10%) increased slowly and tended to remain unchanged after 120 seconds of microwave exposure. In contrast, iPP/CB composites with relatively high CB content (15% and 20%) presented a much faster heating rate and the temperature of the sample kept increasing with the prolongation of exposure time. On the basis of the fact that iPP/CB composites with different CB contents have different microwave heatability, a novel oriented structure, in which the core layer has relatively high orientation and the surface layer has relatively low orientation, was prepared by selective microwave heating. Two-dimensional wide angle X-ray diffraction (2D-WAXD) analysis indicates that the orientation parameter calculated by the (040) plane of the surface layer (0.45) was lower than that of the core layer (0.83). The novel oriented structure is different from the common skin-core structure formed in the samples of semicrystalline polymers by traditional polymer processing methods, in which orientation of the skin layer is higher than that of the core layer. The novel oriented structure has not been reported before to our knowledge and its formation mechanism is also discussed in this paper.
    Journal of Macromolecular Science Part B 01/2012; · 0.63 Impact Factor
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    ABSTRACT: Flow-induced crystallization has long been an important subject in polymer processing. Varying processing conditions can produce different morphologies, which lead to different properties. Recent studies have indicated that the final morphology is, in fact, dictated by the formation of crystallization structures under flow. This study deals with the influence of processing parameters on the polymorphism and crystallization orientation of isotactic polypropylene (iPP) in microinjection molding. Crystallinity and polymorphism were investigated by means of differential scanning calorimeter (DSC) and one-dimensional wide-angle X-ray diffraction (1D-WAXD). Crystalline orientation was characterized by two-dimensional wide-angle X-ray diffraction (2D-WAXD). Herman's orientation functions determined from the flat-plate wide-angle X-ray diffraction patterns were used to evaluate the orientation level of microparts. It was found that the effect of processing parameters on the crystallinity was not obvious, but these processing parameters had a great influence on the β-modification content of microparts. When the mold temperature was 150°C, β-modification still formed in microparts because the thermal stability of the β-modification was enhanced with increasing the mold temperature; The β-modification content of microparts decreased obviously when the injection time was 1 s compared to the longer injection time. However, the β-modification content of microparts increased with increasing the injection pressure. In addition, the γ-modification existed in the microparts at the mold temperatures of 150 and 160°C. From Herman's orientation functions, we know that the influence of processing parameters on α-crystalline orientation in microparts was small. But the processing parameters can affect the degree of the β-modification orientation. A shish-kebab structure was observed in some regions throughout the longitudinal sections of all the microparts by the SEM analysis.
    Journal of Macromolecular Science Part B 11/2011; Part B(Vol. 50):2227-2241. · 0.63 Impact Factor
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    ABSTRACT: To study the effect of vibration field on the electrical conductivity properties of nanocomposites, isotactic polypropylene (iPP)/multiwalled carbon nanotubes (MWCNT) composites were prepared by conventional injection molding and vibration injection molding. Results showed that the electrical conductivity of iPP/MWCNT composites was significantly promoted by vibration injection molding. Vibration injection molded samples had a percolation threshold of about 2.7 wt% compared with the threshold of about 4.5 wt% for conventional injection molded samples. The effects of test locations and vibration frequency on the electrical conductivity of composites were investigated. The samples exhibited an inhomogeneity along the injection direction. The electrical conductivity of the samples was different at different test locations and increased with increasing vibration frequency. Polarized light microscopy (PLM) results indicated that vibration injection molding can induce MWCNT aggregates to be stretched and oriented along the flow direction, which could form conductive networks and greatly enhance the electrical conductivity of iPP/MWCNT composites.
    Journal of Macromolecular Science Part B 11/2011; Part B(Vol. 50):2193-2202. · 0.63 Impact Factor
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    ABSTRACT: The morphological feature of microparts evolved during micro-injection molding may differ from that of the macroparts prepared by conventional injection molding, resulting in specific physical properties. In this study, isotactic polypropylene (iPP) microparts with 200 µm thickness and macroparts with 2000 µm thickness were prepared, and their morphological comparison was investigated by means of polarized light microscopy (PLM), scanning electron microscopy (SEM), differential scanning calorimeter (DSC), and wide-angle X-ray diffraction (WAXD). The results presented some similarities and differences. PLM observations showed that the through-the thickness-morphology of micropart exhibited a similar “skin–core” structure as macropart, but presented a large fraction of shear layer in comparison to the macropart which presented a large fraction of core layer. The SEM observation of shear layer of micropart featured highly oriented shish-kebab structure. The micropart had a more homogeneous distribution of lamellae thickness. The degree of crystallinity of the micropart was found to be higher than that of the macropart. High content of β-crystal was found in micropart. The 2D WAXD pattern of the core layer of macropart showed full Debye rings indicating a random orientation, while the arcing of the shear layer indicates a pronounced orientation. The most pronounced arcing of the micropart indicates the most pronounced orientation of iPP chains within lamellae. Copyright © 2011 John Wiley & Sons, Ltd.
    Polymers for Advanced Technologies 03/2011; 23(3):686 - 694. · 1.64 Impact Factor
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    ABSTRACT: In this study, isotactic polypropylene (iPP) samples were prepared by conventional injection molding (CIM) and pressure vibration injection molding (PVIM), in which a periodical shear field was imposed on the iPP melt during the cooling solidification. The distribution of supermolecular structures of samples was investigated by Polarized Light Microscopy (PLM) and Scanning Electron Microscopy (SEM). Results show that the through-the thickness-morphology of sample prepared by CIM features a typical skin-core structure, as a result of general shear-induced crystallization. This structure can be divided into three layers, including a skin layer in which the shish–kebab structure was found, a transition region with deformed spherulite structure and a core layer with spherulitic structure. However, the morphology of the sample prepared by PVIM, as a result of periodical shear-induced crystallization, features a richer and fascinating supermolecular structure and can not be roughly divided into three layers. A region full of shish–kebab-like cylindrulite structures was found between the transition region and the core layer, which is rare to be seen in conventional injection molding. Based on their various core structures, two kinds of shish–kebab-like cylindrulites were defined: one is multi-fibril-core cylindrulite of which core is an assembly of multiple fibrils, and the other is single-fibril-core cylindrulite of which the core just contains a single fibril. Based on the investigated results, a schematic illustration is proposed to depict the through-the thickness-distribution of supermolecular structure of iPP sample prepared by PVIM. The mechanism of the formation of the two kinds of shish–kebab-like cylindrulite structures is also depicted by a schematic illustration, and it was discussed in terms of periodical shear-induced crystallization.
    Polymer. 01/2011; 52(13):2970-2978.
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    ABSTRACT: Currently, environmental pollution caused by organic compounds leads to severe negative consequences in the human society. Therefore, the removal of these pollutants from aqueous media has become one of the most important issues in environmental science. In the present study, CdS QDs were successfully prepared under aqueous conditions using L-arginine as the stabilizing agent. Optical property determination results reveal that the CdS QDs exhibited strong absorption and photoluminescence in a visible wavelength region. Moreover, the CdS QDs could effectively degrade two organic dyes under visible light irradiation. This suggested that the CdS QDs prepared in this work might be used as the potential photocatalyst to effectively treat the organic pollutants under visible light irradiation. 漏 2010 Elsevier B.V. All rights reserved.
    Materials Letters. 01/2011; 65(3):486-489.
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    ABSTRACT: Cadmium sulfide flower-like 3D assemblies were successfully prepared through a facile additive-free solvothermal process. It was found that the ethanol played an important role in the formation of the CdS assemblies. Based on the time-dependent experiments, a possible mechanism was proposed. In addition, the CdS assemblies exhibit unique optical properties and potential photocatalytic activity.
    CrystEngComm 01/2011; 13(16):5045-5048. · 3.88 Impact Factor
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    ABSTRACT: A self-designed pressure vibration injection molding device was used to study the effect of vibration frequency and vibration pressure on tensile strength and impact strength of PP/HDPE (70/30) samples prepared by vibration injection molding. Furthermore, DSC and scanning electron microscopy (SEM) observations were conducted. The tensile strength and impact strength increase with increasing vibration frequency and vibration pressure. SEM micrographs show that the orientation degree of the vibration sample obtained at 190°C obviously increases compared with the static sample, and the clusters of lamellae are stretched along the flow direction, whereas their lateral sizes decrease correspondingly. There is no evident orientation in the core layer of the vibration sample obtained at 230°C. DSC testing results show that the degree of crystallinity of vibration samples are higher than those of static samples.
    Journal of Macromolecular Science. 01/2011; Part B(Vol. 50):41-50.
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    ABSTRACT: Copper sulfide amorphous nanoparticles and nanocrystals were prepared successfully by a special process. These CuS nanoparticles could specifically and significantly induce the apoptosis and inhibit the proliferation of human cancer cells rather than normal cells. Moreover, the biological activities of these nanoparticles are related to their polymorphs.
    Chemical Communications 04/2010; 46(20):3493-5. · 6.38 Impact Factor
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    ABSTRACT: A high-efficiency platinum catalyst stabilized with sodium citrate for methanol oxidation is introduced in this paper, in which freshly prepared non-noble active cobalt is employed as reducer. According to X-ray diffraction (XRD) and transmission electron microscopy (TEM) measurements, the novel as-prepared nanoclusters Pt catalyst dispersed on carbon is composed of Pt nanoparticles, and the average particle size of the Pt nanoparticles is 2.0 nm. The catalyst with sodium citrate shows a very high electrochemically active surface area and significant increase electrocatalytic activity towards methanol oxidation, which indicates that it would be a better potential candidate for application in a direct methanol fuel cell (DMFC). 漏 2009 Elsevier B.V. All rights reserved.
    Journal of Power Sources. 01/2010; 195(9):2653-2658.
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    ABSTRACT: Microwave processing has numerous advantages over traditional methods of heating. Most thermoplastics, such as high-density polyethylene (HDPE), are nearly transparent to electromagnetic radiation. Carbon black (CB) filled HDPE was prepared in order to improve the microwave heatability of HDPE. The heating response of HDPE/CB composites to microwave exposure and the effects of this exposure on the mechanical and physical properties of material were investigated. The addition of CB particles improved the microwave heatability of HDPE, and microwave heatability of composites varied with CB content, in which an average temperatures of up to 139 °C above ambient were measured for 20 wt% CB composites after a exposure duration of 150 s. Microwave exposure had no obvious effect on rheological property of HDPE/CB composites. Mechanical properties of HDPE/CB composites are relatively improved after microwave exposure. Scanning electronic micrograph (SEM) analysis presented that the interface defects between CB particles and HDPE matrix are significantly reduced and a better combination was found after microwave exposure. Differential scanning calorimetry (DSC) analysis showed that the melt point of HDPE with CB shifted toward high temperature and degree of crystallinity increased after microwave exposure.
    Journal of Materials Processing Technology 01/2010; 210(14):1991-1996. · 1.95 Impact Factor
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    ABSTRACT: Protein-conjugated PbS nanocrystals with the average sizes of 15, 25, and 35 nm have been synthesized by adjusting the concentration of the bovine serum albumin (BSA) solution at room temperature. The obtained BSA-conjugated PbS nanoparticles have been characterized by powder X-ray diffraction, transmission electron microscopy, selected-area electron diffraction, high-resolution transmission electron microscopy, thermal analyses and photoluminescence. The quantum-confined effect of the BSA-conjugated PbS nanoparticles has been confirmed by the UV-vis spectra. The results indicated that the BSA not only induced the nucleation, but inhibited the further growth of PbS nanocrystals. The effect of Pb<sup>2+</sup> on BSA and the change of BSA conformation were studied through Fourier transform infrared spectroscopy and circular dichroism spectroscopy. The possible mechanism of BSA-conjugated PbS nanoparticles growth was also discussed. 漏 2009 Elsevier B.V. All rights reserved.
    Materials Chemistry and Physics. 01/2010; 119(1-2):112-117.