Baoquan Xie

Publications (10)34.2 Total impact

• Article: Behavioral improvements and brain functional alterations by motor imagery training.

  Hang Zhang, Lele Xu, Shuling Wang, Baoquan Xie, Jia Guo, Zhiying Long, Li Yao
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  ABSTRACT: Motor imagery training is considered as an effective training strategy for motor skill learning and motor function rehabilitation. However, compared with studies of the neural mechanism underlying motor imagery, neuroimaging examinations of motor imagery training are comparatively few. Using functional magnetic resonance imaging, we designed a 2-week motor imagery training experiment, including execution and imagery tasks, to investigate the effectiveness of motor imagery training on the improvement of motor performance, as well as the neural mechanism associated with motor imagery training. Here, we examined the motor behavior, brain activation, and correlation between the behavior of the motor execution task and the brain activation across task-related region of interests (ROIs) in both pre- and post-test phases. Our results demonstrated that motor imagery training could improve motor performance. More importantly, the brain functional alterations induced by training were found in the fusiform gyrus for both tasks. These findings provide new insights into motor imagery training.
  Brain research 08/2011; 1407:38-46. · 2.46 Impact Factor
• Article: Phase change materials of n-alkane-containing microcapsules: observation of coexistence of ordered and rotator phases.

  Dongsheng Fu, Yunlan Su, Baoquan Xie, Haijin Zhu, Guoming Liu, Dujin Wang
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  ABSTRACT: In the present investigation, the crystallization and phase transition behaviours of normal alkane (n-docosane) in microcapsules with a mean diameter of 3.6 μm were studied by the combination of differential scanning calorimetry (DSC), temperature-dependent X-ray diffraction (XRD) and variable-temperature solid-state nuclear magnetic resonance (VT solid-state (13)C NMR). The DSC and VT solid-state (13)C NMR results reveal that a surface freezing monolayer is formed prior to the bulk crystallization of the microencapsulated n-docosane. More interestingly, it is confirmed that after the bulk crystallization, the ordered triclinic phase coexists with the rotator phase I (RI) for the microencapsulated n-docosane. We argue that the reduction of the free energy difference between the two phases, resulting from the microencapsulation process, leads to the coexistence of the ordered triclinic and rotator phases of the normal alkanes.
  Physical Chemistry Chemical Physics 02/2011; 13(6):2021-6. · 3.57 Impact Factor
• Source

  Available from: pnas.org

  Article: How to control the size and morphology of apatite nanocrystals in bone.

  Baoquan Xie, George H Nancollas
  Proceedings of the National Academy of Sciences 12/2010; 107(52):22369-70. · 9.68 Impact Factor
• Article: Solid-solid phase transition of n-alkanes in multiple nanoscale confinement.

  Kai Jiang, Baoquan Xie, Dongsheng Fu, Faliang Luo, Guoming Liu, Yunlan Su, Dujin Wang
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  ABSTRACT: The crystallization behavior of n-C(19)H(40)/SiO(2) nanosphere composites was investigated by a combination of differential scanning calorimetry (DSC) and temperature-dependent X-ray diffraction (XRD). Three kinds of confined alkanes with different solid-solid phase transition supercoolings and a surface (or interface) freezing monolayer of n-C(19)H(40) at the bulk liquid/SiO(2) interface were found in the composites at high SiO(2) loading. The surface freezing monolayer induces the chain packing of bulk alkanes by forming a 2D close-packed arrangement without long-range positional ordering in 3D space. A homogeneous nucleation and growth mechanism is found for the solid-solid transition in confined geometry, in which the supercooling of the transition is sensitive to the confined size.
  The Journal of Physical Chemistry B 12/2009; 114(3):1388-92. · 3.70 Impact Factor
• Article: Suppression of the phase separation in binary n-alkane solid solutions by geometrical confinement.

  Kai Jiang, Yunlan Su, Baoquan Xie, Yanfeng Meng, Dujin Wang
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  ABSTRACT: The crystallization of binary n-alkane solid solution n-C(18)H(38)/n-C(19)H(40) = 90/10 (molar ratio) (abbreviated as C(18)/C(19) = 90/10) and the microencapsulated counterpart (abbreviated as m-C(18)/C(19) = 90/10) has been investigated by a combination of differential scanning calorimetry (DSC) and temperature-dependent X-ray diffraction (XRD). The solid-solid phase separation was obviously detected in C(18)/C(19) = 90/10 by XRD, which is absent in m-C(18)/C(19) = 90/10. The XRD data also show that the chain packing of m-C(18)/C(19) = 90/10 is different from that of bulk C(18)/C(19) = 90/10. The packing mode of m-C(18)/C(19) = 90/10 molecular chains is unique; i.e., the n-alkane chains pack along the longitudinal direction and the neighboring layers interdigitate with each other, subsequently resulting in the deconstruction of lamellar ordering. The extinction of phase separation in m-C(18)/C(19) = 90/10 can be understood in terms of the suppression of longitudinal chain diffusion caused by the special three-dimensional confinement effect provided by microcapsules.
  The Journal of Physical Chemistry B 03/2009; 113(11):3269-72. · 3.70 Impact Factor
• Article: Effect of geometrical confinement on the nucleation and crystallization behavior of n-alkane mixtures.

  Kai Jiang, Yunlan Su, Baoquan Xie, Shichun Jiang, Ying Zhao, Dujin Wang
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  ABSTRACT: The condensed structure of normal alkane (n-alkane) mixtures in confined geometry is an interesting topic concerning the difference in crystallization behavior of odd and even alkanes. In the present work, the crystallization of mixtures of normal octadecane (n-C18H38) and normal nonadecane (n-C19H40) in microcapsules with narrow size distribution was investigated using the combination of differential scanning calorimetry (DSC) and X-ray diffraction (XRD). A surface freezing monolayer for microencapsulated n-C18H38, n-C19H40, and their mixture was detected by DSC, which for the mixture is a mixed homogeneous crystalline phase with continuous change in the composition. A more stable rotator phase (RI) was observed for the microencapsulated n-C18H38/n-C19H40 = 95/5 (molar ratio) mixture, confirmed by an increased supercooling of the transition from RI to stable phase compared to that of the mixture in bulk. Two nucleation mechanisms were speculated as "liquid-to-solid" heterogeneous nucleation and "solid-to-solid" homogeneous nucleation, which occur at different crystallization stages in microcapsules and might be attributed to the surface effect and confinement effect, respectively, in the confined geometry.
  The Journal of Physical Chemistry B 01/2009; 112(51):16485-9. · 3.70 Impact Factor
• Article: Crystallization behaviors of n-octadecane in confined space: crossover of rotator phase from transient to metastable induced by surface freezing.

  Baoquan Xie, Guoming Liu, Shichun Jiang, Ying Zhao, Dujin Wang
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  ABSTRACT: In this paper, the confined crystallization and phase transition behaviors of n-octadecane in microcapsules with a diameter of about 3 microm were studied with the combination of differential scanning calorimetry (DSC), temperature dependent Fourier transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD). The main discovery is that the microencapsulated n-octadecane crystallizes into a stable triclinic phase via a mestastable rotator phase (R I), which emerges as a transient state for the bulk n-octadecane and is difficult to be detected by the commonly used characterization methods. As evident from the DSC measurement, a surface freezing monolayer, which is formed at the interface between the microcapsule inner wall and n-octadecane, induces the crossover of the R I from transient to metastable. We argue that the existence of the surface freezing monolayer decreases the nucleating potential barrier of the R I phase, and consequently the lower relative nucleation barrier in the confined geometry turns the transient R I phase into a metastable one.
  The Journal of Physical Chemistry B 10/2008; 112(42):13310-5. · 3.70 Impact Factor
• Article: Preparation of Surface Porous Microcapsules Templated by Self-assembly of Nonionic Surfactant Micelles

  Baoquan Xie, Haifeng Shi, Guoming Liu, Yong Zhou, Yang Wang, Ying Zhao, Dujin Wang
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  ABSTRACT: Microcapsules with controllable porous surface morphology and good monodispersity were prepared using the one-step synthetic strategy by employing the self-assembly template of nonionic surfactant micelles above its cloud point. Both the pore size (from 100 to 400 nm) and pore density are tunable by changing the amount of core materials or the ratio of core material to shell material. This methodology provides a versatile and effective route for preparation of porous microsphere materials, which can encapsulate lipophilic functional compounds.
  04/2008;
• Article: Crystallization behaviors of n-nonadecane in confined space: observation of metastable phase induced by surface freezing.

  Baoquan Xie, Haifeng Shi, Shichun Jiang, Ying Zhao, Charles C Han, Duanfu Xu, Dujin Wang
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  ABSTRACT: Crystallization and phase transition behaviors of n-nonadecane in microcapsules with a diameter of about 5 mum were studied with the combination of differential scanning calorimetry (DSC) and synchrotron radiation X-ray diffraction (XRD). As evident from the DSC measurement, a surface freezing monolayer, which is formed in the microcapsules before the bulk crystallization, induces a novel metastable rotator phase (R(II)), which has not been reported anywhere else. We argue that the existence of the surface freezing monolayer decreases the nucleating potential barrier of the R(II) phase and induces its appearance, while the lower free energy in the confined geometry turns the transient R(II) phase to a "long-lived" metastable phase.
  The Journal of Physical Chemistry B 08/2006; 110(29):14279-82. · 3.70 Impact Factor
• Article: Synthesis of amphiphilic triblock copolymers and application for morphology control of calcium carbonate crystals

  Hengrui Yang, Yunlan Su, Haijin Zhu, Hui Zhu, Baoquan Xie, Ying Zhao, Yongming Chen, Dujin Wang
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  ABSTRACT: A series of amphiphilic triblock copolymers poly(ethylene glycol)-block-poly(acrylic acid)-block-poly(n-butyl acrylate) (PEG-b-PAA-b-PnBA) differing only in the relative block lengths were synthesized by the acid-catalyzed elimination of the tert-butyl groups from poly(ethylene glycol)-block-poly(tert-butyl acrylate)-block-poly(n-butyl acrylate) (PEG-b-PtBA-b-PnBA), which was synthesized by atom-transfer radical polymerization (ATRP). The degree of polymerization, molecular weight and percentage of hydrolysis of the product PEG-b-PAA-b-PnBA were studied by gel permeation chromatography (GPC), NMR and matrix-assisted laser desorption/ionization time-of-flight mass spectroscopy (MALDI-TOF-MS). Dynamic light scattering (DLS) and transmission electron microscopy (TEM) were used to study the aggregation states of copolymers in water solution. The radii of the copolymer micelles shrink as Ca2+ is introduced into the solutions. The crystallization behaviors of calcium carbonate controlled by copolymer 1 (PEG112-b-PAA86-b-PnBA60) and copolymer 2 (PEG112-b-PAA40-b-PnBA72) differing mainly in the length of PAA block were systematically studied. It was found that the crystallization products are composed of calcite and vaterite, and the ratio of vaterite to calcite increases with increasing the concentration of copolymer 1. For copolymer 2, however, only calcite is obtained at all the concentration range investigated in this work.
  Polymer. 48(15):4344-4351.