Xiang Y Liu

Soochow University (PRC), Suzhou, Jiangsu Sheng, China

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Publications (11)96.35 Total impact

  • Ke-Qin Zhang, Xiang Y Liu
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    ABSTRACT: A detailed phase diagram, revealing a variety of processes including various colloidal structures of monodisperse charged colloidal particles from the colloidal chains, vortex rings, three-dimensional aggregation to a two-dimensional crystal under different frequencies, and strengths of an alternating electric field, is obtained for the first time. The occurrence of different colloidal structures is driven by the electrohydrodynamic interaction and induced dipolar interaction near the polarized layer on the electrode. This simple colloidal system can be employed as a model system to understand the complex phase behavior of the assembly/aggregation of the nanoparticles and biomacromolecules under external perturbation. Detailed phase diagram provides vital guidance for the fabrication of desired colloidal structures with single-particle resolution, which could be employed as a sort of templates for nanolithography or imprinting. Moreover, the sensitivity of the electrohydrodynamic interaction on the particle size and the dependence of the convective flow on the frequency and strength could be utilized in microfluidic devices for manipulating nanoparticles, biomacromolecules, and vesicles.
    The Journal of Chemical Physics 06/2009; 130(18):184901. · 3.12 Impact Factor
  • Ke-Qin Zhang, Xiang Y Liu
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    ABSTRACT: We present a noncontact, accurate, and efficient methodology for determination of elastic constants in two-dimensional colloidal crystals via the calculation of the local strain fluctuation of particles. The hexagonally close-packed colloidal crystals form from microsized particles subjected to an alternating electric field. The elastic constants in the thermodynamic limit are obtained by the extrapolation of finite-size scaling of the elastic moduli as the functions of the frequency and field strength. It is found that the elastic constants in our system are larger than those in non-close-packed colloidal crystals reported before. This technique could be a rational method to study the elasticity of soft solids.
    Langmuir 05/2009; 25(10):5432-6. · 4.38 Impact Factor
  • Ning Du, Xiang Y. Liu
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    ABSTRACT: It is found that ice nucleation can be effectively suppressed by antifreeze protein at certain concentrations of electrolyte, because of the neutralization of the surface charge of the antifreeze protein molecules by the counterions. It follows from our ice crystallization experiment that the enhancement of antifreeze efficiency is based on the increase of the kink kinetics barrier of surface integration of water molecules and the disruption of the interfacial match between water and foreign particles by antifreeze protein molecules in the presence of electrolyte. This effect is attributed to the optimal packing of the antifreeze protein molecules on the surface of the ice nuclei as well as of the foreign particles when electrolyte ions are added. This work could provide a model for the study of the specific role of an electrolyte on the antifreeze efficiency of antifreeze proteins. The new understanding suggests another way to increase the antifreeze efficiency of the antifreeze proteins and provides us with a new insight into the antifreeze mechanism of antifreeze proteins on ice crystallization.
    Crystal Growth & Design - CRYST GROWTH DES. 07/2008; 8(9).
  • Ke-Qin Zhang, Xiang Y. Liu
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    ABSTRACT: The authors demonstrate that two-dimensional crystals can be assembled from suspensions of colloidal spheres subjected to an alternating electric field on the surface of electrodes. The order parameters of monolayer colloidal crystals, which are extracted from the translational correlation function g(r) and bond-orientational correlation function g<sub>6</sub>(r) , are employed to quantitatively characterize the ordering of the colloidal assemblies. This method has been applied on colloidal spheres of various sizes ranging from 450 nm to 5.0 μ m . In particular, high-quality crystals of spheres sized differently are controlled by different domains of frequency. This technique could be a rational method to assemble micro- or submicron colloidal spheres.
    Applied Physics Letters 04/2007; · 3.79 Impact Factor
  • Ning Du, Xiang Y Liu, Choy L Hew
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    ABSTRACT: Antifreeze protein type III aggregates once the concentration exceeds a critical value, the so-called critical aggregation concentration (CAC). It was found for the first time that the aggregation of antifreeze protein exerts a direct impact on the antifreeze efficiency. It follows from our measurements that the AFP III above CAC will enhance the antifreeze activity because of the increase of the kink kinetics barrier of surface integration. This is attributed to the optimal packing of AFP III molecules on the surface of the ice nucleus as well as ice crystals above CAC. This study will extend our understanding of the antifreeze mechanism of antifreeze protein monomers as well as antifreeze aggregates on ice nucleation and shed light on the selection of antifreeze agents.
    The Journal of Physical Chemistry B 11/2006; 110(41):20562-7. · 3.61 Impact Factor
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    Ke-Qin Zhang, Xiang Y Liu
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    ABSTRACT: A two-dimensional assembly of charged colloidal particles induced by an alternating electric field was studied in real space by means of digital video microscopy. Phase transitions occur from a highly ordered colloidal monolayer to an isotropic suspension by changing the field strength or frequency (in the appropriate range). In particular, it is found that the strength-dependent phase transition is an infinite-order phase transition, in contrast with the frequency-dependent phase transition, which is a second-order phase transition.
    Physical Review Letters 04/2006; 96(10):105701. · 7.73 Impact Factor
  • Xiang Y Liu
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    ABSTRACT: The mechanism of fiber and fiber network formation of small molecular gelling agents is treated on the basis of a generic heterogeneous nucleation model. The formation of a crystallite fiber network can take place via the so-called crystallographic mismatch branching. At very low supersaturations, unbranched fibers form predominantly. As supersaturation increases, small-angle crystallographic mismatch branching occurs at the side face of growth fibers. At very high supersaturations, the so-called wide-angle crystallographic mismatch branching becomes kinetically favorable. Both give rise to the formation of fiber networks, but of different types. Controlling the branching of the nanofibers of small molecular gelatins allows us to achieve the micro/nanostructure architecture of networks having the desired rheological properties. In this regard, the engineering of supramolecular functional materials can be achieved by constructing and manipulating the micro/nanostructure in terms of a "branching creator", or by tuning processing conditions.
    Topics in current chemistry 01/2005; 256:1-37. · 8.46 Impact Factor
  • Ke-Qin Zhang, Xiang Y Liu
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    ABSTRACT: The nucleation of crystalline materials is a hotly debated subject in the physical sciences. Despite the emergence of several theories in recent decades, much confusion still surrounds the dynamic processes of nucleation. This has been due in part to the limitations of existing experimental evidence. Charged colloidal suspensions have been used as experimental model systems for the study of crystal nucleation and structural phase transitions, as their crystallization phase diagram is analogous to that of atomic and molecular systems, but they can be visualized using microscopy. Previously, three-dimensional imaging of colloidal nucleation dynamics was achieved using confocal microscopy. However, the limited temporal resolution of the confocal microscope is of concern when trying to capture real-time colloidal crystal nucleation events. Moreover, as the thermodynamic driving force has remained undefined, data on key factors such as the critical nuclei size are at best semiquantitative. Here we present real-time direct imaging and quantitative measurements of the pre- and post-nucleation processes of colloidal spheres, and the kinetics of nucleation driven by an alternating electric field, under well-defined thermodynamic driving forces. Our imaging approach could facilitate the observation of other rarely observed phenomena, such as defect and grain-boundary formation and the effects of foreign particles during crystallization. Furthermore, it may prove useful in identifying optical and biological technologies based on colloids.
    Nature 07/2004; 429(6993):739-43. · 38.60 Impact Factor
  • Ning Du, Xiang Y Liu, Choy Leong Hew
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    ABSTRACT: The effect of antifreeze protein type III (one type of fish antifreeze protein) on ice crystallization was examined quantitatively based on a "micro-sized ice nucleation" technique. It was found for the first time that antifreeze proteins can inhibit the ice nucleation process by adsorbing onto both the surfaces of ice nuclei and dust particles. This leads to an increase of the ice nucleation barrier and the desolvation kink kinetics barrier, respectively. Based on the latest nucleation model, the increases in the ice nucleation barrier and the kink kinetics barrier were measured. This enables us to quantitatively examine the antifreeze mechanism of antifreeze proteins for the first time.
    Journal of Biological Chemistry 10/2003; 278(38):36000-4. · 4.65 Impact Factor
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    Xiang Y Liu, See Wai Lim
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    ABSTRACT: The structural synergy between biominerals (CaCO(3), hydroxyapatite) and biosubstrates were examined for the first time. The templating effect of substrate and a newly identified supersaturation-driven interfacial structure mismatch effect were identified in the context of a new nucleation model. It follows that the heterogeneous nucleation which corresponds to a good structural match and synergy between biominerals and substrates will promote an ordered, compact, and tough complex biomineral structure, and occur only at low supersaturations, whereas at high supersaturations the heterogeneous nucleation associated with a poor structural match and synergy between biominerals and substrates will become dominant due to supersaturation-driven interfacial structural mismatch. The latter normally results in a disordered and porous structure. A phenomenon, so-called microgravity-driven homogeneous nucleation, was also examined. It turns out that microgravity will suppress convection and consequently promote homogeneous-like nucleation during biomineralization. This could be responsible for microgravity-induced osteoporousis.
    Journal of the American Chemical Society 02/2003; 125(4):888-95. · 10.68 Impact Factor
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    Xiang Y Liu, Prashant D Sawant
    Angewandte Chemie International Edition 11/2002; 41(19):3641-5, 3518. · 11.34 Impact Factor