Hua-Kun Liu

Bio: Hua-Kun Liu is an academic researcher from University of Wollongong. The author has contributed to research in topics: Lithium & Anode. The author has an hindex of 116, co-authored 799 publications receiving 51764 citations. Previous affiliations of Hua-Kun Liu include Nanyang Technological University & Commonwealth Scientific and Industrial Research Organisation.

Influenza neuraminidase inhibitors possessing a novel hydrophobic interaction in the enzyme active site: design, synthesis, and structural analysis of carbocyclic sialic acid analogues with potent anti-influenza activity.

Abstract: The design, synthesis, and in vitro evaluation of the novel carbocycles as transition-state-based inhibitors of influenza neuraminidase (NA) are described. The double bond position in the carbocyclic analogues plays an important role in NA inhibition as demonstrated by the antiviral activity of 8 (IC50 = 6.3 μM) vs 9 (IC50 > 200 μM). Structure−activity studies of a series of carbocyclic analogues 6a−i identified the 3-pentyloxy moiety as an apparent optimal group at the C3 position with an IC50 value of 1 nM for NA inhibition. The X-ray crystallographic structure of 6h bound to NA revealed the presence of a large hydrophobic pocket in the region corresponding to the glycerol subsite of sialic acid. The high antiviral potency observed for 6h appears to be attributed to a highly favorable hydrophobic interaction in this pocket. The practical synthesis of 6 starting from (−)-quinic acid is also described.

Preparation and Electrochemical Properties of SnO2 Nanowires for Application in Lithium-Ion Batteries

Abstract: One-dimensional (1D) nanostructured materials have received considerable attention for advanced functional systems as well as extensive applications owing to their attractive electronic, optical, and thermal properties. In lithium-ion-battery science, recent research has focused on nanoscale electrode materials to improve electrochemical performance. The high surface-to-volume ratio and excellent surface activities of 1D nanostructured materials have stimulated great interest in their development for the next generation of power sources. Materials based on tin oxide have been proposed as alternative anode materials with high-energy densities and stable capacity retention in lithium-ion batteries. Various SnO2-based materials have displayed extraordinary electrochemical behavior such that the initial irreversible capacity induced by Li2O formation and the abrupt capacity fading caused by volume variation could be effectively reduced when in nanoscale form. From this point of view, SnO2 nanowires can also be suggested as a promising anode material because the nanowire structure is of special interest with predictions of unique electronic and structural properties. Furthermore, the nanowires can be easily synthesized by a thermal evaporation method. However, in its current form, this method of manufacture of SnO2 nanowires has several limitations: it is inappropriate for mass production as high synthesis temperatures are required and there are difficulties in the elimination of metal catalysts that could act as impurities or defects. This results in reversible capacity loss or poor cyclic performance during electrochemical reactions. 12] The critical issues relating to SnO2 nanowires as anode materials for lithium-ion batteries are how to avoid the deteriorative effects of catalysts and how to increase production. Herein, we report on the preparation and electrochemical performance of self-catalysis-grown SnO2 nanowires to determine their potential use as an anode material for lithium-ion batteries. SnO2 nanowires have been synthesized by thermal evaporation combined with a self-catalyzed growth procedure by using a ball-milled evaporation material to increase production at lower temperature and prevent the undesirable effects of conventional catalysts on electrochemical performance. The self-catalysis-grown SnO2 nanowires show higher initial coulombic efficiency and an improved cyclic retention compared with those of SnO2 powder and SnO2 nanowires produced by Au-assisted growth. The self-catalysis growth method, which uses a ball-milled mixture of SnO and Sn powder as an evaporation source, is appropriate for obtaining SnO2 nanowires with high purity. The deposited products on the Si substrates contain almost 100% of the SnO2 nanowires formed. Observation with scanning electron microscopy (SEM) clearly shows a general view of randomly aligned SnO2 nanowires with diameters of 200–500 nm and lengths extending to several tens of micrometers (Figure 1a). Sn droplets at the tips of nanowires were observed and confirmed by energy dispersive X-ray (EDX)

Enhancement of the critical current density and flux pinning of MgB2 superconductor by nanoparticle SiC doping

Abstract: Doping of MgB2 by nano-SiC and its potential for the improvement of flux pinning were studied for MgB2−x(SiC)x/2 with x=0, 0.2, and 0.3 and for 10 wt % nano-SiC-doped MgB2 samples. Cosubstitution of B by Si and C counterbalanced the effects of single-element doping, decreasing Tc by only 1.5 K, introducing intragrain pinning centers effective at high fields and temperatures, and significantly enhancing Jc and Hirr. Compared to the undoped sample, Jc for the 10 wt % doped sample increased by a factor of 32 at 5 K and 8 T, 42 at 20 K and 5 T, and 14 at 30 K and 2 T. At 20 K and 2 T, the Jc for the doped sample was 2.4×105 A/cm2, which is comparable to Jc values for the best Ag/Bi-2223 tapes. At 20 K and 4 T, Jc was twice as high as for the best MgB2 thin films and an order of magnitude higher than for the best Fe/MgB2 tapes. The magnetic Jc is consistent with the transport Jc which remains at 20 000 A/cm2 even at 10 T and 5 K for the doped sample, an order of magnitude higher than the undoped one. Because o...

Highly reversible lithium storage in spheroidal carbon-coated silicon nanocomposites as anodes for lithium-ion batteries.

Abstract: [*] S.-H. Ng, Dr. J. Wang, Dr. K. Konstantinov, Dr. Z.-P. Guo, Prof. H.-K. Liu Institute for Superconducting & Electronic Materials and ARC Centre of Excellence for Electromaterials Science University of Wollongong Wollongong, NSW 2522 (Australia) Fax: (+61)2-4221-5731 E-mail: hua_liu@uow.edu.au Homepage: http://www.uow.edu.au/eng/research/isem/staff/ hkliu.html Dr. D. Wexler Faculty of Engineering University of Wollongong Wollongong, NSW 2522 (Australia) [**] Financial support provided by the Australian Research Council (ARC) through the ARC Centre of Excellence funding (CE0561616) is gratefully acknowledged. Moreover, the authors are grateful to SauYen Chew at the University of Wollongong for experimental assistance. Finally, we also thank Dr. Tania Silver at the University of Wollongong for critical reading of the manuscript. Supporting information for this article is available on the WWW under http://www.angewandte.org or from the author. Communications

Boosted Charge Transfer in SnS/SnO2 Heterostructures: Toward High Rate Capability for Sodium‐Ion Batteries

Abstract: Constructing heterostructures can endow materials with fascinating performance in high-speed electronics, optoelectronics, and other applications owing to the built-in charge-transfer driving force, which is of benefit to the specific charge-transfer kinetics. Rational design and controllable synthesis of nano-heterostructure anode materials with high-rate performance, however, still remains a great challenge. Herein, ultrafine SnS/SnO2 heterostructures were successfully fabricated and showed enhanced charge-transfer capability. The mobility enhancement is attributed to the interface effect of heterostructures, which induces an electric field within the nanocrystals, giving them much lower ion-diffusion resistance and facilitating interfacial electron transport.

I and i

Abstract: There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality. Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

Materials for electrochemical capacitors

Abstract: Electrochemical capacitors, also called supercapacitors, store energy using either ion adsorption (electrochemical double layer capacitors) or fast surface redox reactions (pseudo-capacitors). They can complement or replace batteries in electrical energy storage and harvesting applications, when high power delivery or uptake is needed. A notable improvement in performance has been achieved through recent advances in understanding charge storage mechanisms and the development of advanced nanostructured materials. The discovery that ion desolvation occurs in pores smaller than the solvated ions has led to higher capacitance for electrochemical double layer capacitors using carbon electrodes with subnanometre pores, and opened the door to designing high-energy density devices using a variety of electrolytes. Combination of pseudo-capacitive nanomaterials, including oxides, nitrides and polymers, with the latest generation of nanostructured lithium electrodes has brought the energy density of electrochemical capacitors closer to that of batteries. The use of carbon nanotubes has further advanced micro-electrochemical capacitors, enabling flexible and adaptable devices to be made. Mathematical modelling and simulation will be the key to success in designing tomorrow's high-energy and high-power devices.

Graphene and Graphene Oxide: Synthesis, Properties, and Applications

Abstract: There is intense interest in graphene in fields such as physics, chemistry, and materials science, among others. Interest in graphene's exceptional physical properties, chemical tunability, and potential for applications has generated thousands of publications and an accelerating pace of research, making review of such research timely. Here is an overview of the synthesis, properties, and applications of graphene and related materials (primarily, graphite oxide and its colloidal suspensions and materials made from them), from a materials science perspective.