HKU Zhejiang Institute of Research and Innovation HKU ZIRI

Hangzhou, China

HKU Zhejiang Institute of Research and Innovation HKU ZIRI

Hangzhou, China

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Khan A.,University of Hong Kong | Huang Y.-T.,University of Hong Kong | Miyasaka T.,Toin University of Yokohama | Ikegami M.,Toin University of Yokohama | And 5 more authors.
ACS Applied Materials and Interfaces | Year: 2017

A new type of embedded metal-mesh transparent electrode (EMTE) with in-situ electrodeposited catalytic platinum nanoparticles (PtNPs) is developed as a high-performance counter electrode (CE) for lightweight flexible bifacial dye-sensitized solar cells (DSSCs). The thick but narrow nickel micromesh fully embedded in a plastic film provides superior electrical conductivity, optical transmittance, and mechanical stability to the novel electrode. PtNPs decorated selectively on the nickel micromesh surface provide catalytic function with minimum material cost and without interfering with optical transparency. Facile and fully solution-processed fabrication of the novel CE is demonstrated with potential for scalable and cost-effective production. Using this PtNP-decorated nickel EMTE as the CE and titanium foil as the photoanode, unifacial flexible DSSCs are fabricated with a power conversion efficiency (PCE) of 6.91%. By replacing the titanium foil with a transparent ITO-PEN photoanode, full-plastic bifacial DSSCs are fabricated and tested, demonstrating a remarkable PCE of 4.87% under rear-side illumination, which approaches 85% of the 5.67% PCE under front-side illumination, among the highest ratio in published results. These promising results reveal the enormous potential of this hybrid transparent CE in scalable production and commercialization of low-cost and efficient flexible DSSCs. © 2017 American Chemical Society.

Kong T.,University of Hong Kong | Kong T.,HKU Zhejiang Institute of Research and Innovation HKU ZIRI | Shum H.C.,University of Hong Kong | Shum H.C.,HKU Shenzhen Institute of Research and Innovation HKU SIRI | And 2 more authors.
Biomicrofluidics | Year: 2013

We report a facile and robust microfluidic method to fabricate polymeric core-shell microspheres as delivery vehicles for biomedical applications. The characteristics of core-shell microspheres can be precisely and easily tuned by manipulating the microfluidic double emulsion templates. The addition of a shell can significantly improve the versatility as well as functionality of these microspheres as delivery vehicles. We demonstrate that the nature of the shell material plays an important role in the properties of the core-shell delivery vehicles. The release kinetics is significantly influenced by the material of the shell and other characteristics such as the thickness. For example, by adding a poly(lactic-co-glycolic acid) (PLGA) shell to an alginate core, the encapsulation efficiency is enhanced and undesired leakage of hydrophilic actives is prevented. By contrast, adding an alginate shell to PLGA core can lead to a reduction of the initial release rate, thus extending the release period of hydrophobic actives. Microfluidic fabrication enables the generation of precisely controlled core-shell microspheres with a narrow size distribution, which enables the investigation of the relationship between the release kinetics of these microspheres and their characteristics. The approach of using core-shell particles as delivery vehicles creates new opportunities to customize the release kinetics of active ingredients. © 2013 AIP Publishing LLC.

Bao S.,University of Hong Kong | Zhou X.,Tsinghua University | Zhang L.,Harbin Medical University | Zhou J.,University of Hong Kong | And 6 more authors.
BMC Genomics | Year: 2013

Background: The genetic make-up of humans and other mammals (such as mice) affects their resistance to influenza virus infection. Considering the complexity and moral issues associated with experiments on human subjects, we have only acquired partial knowledge regarding the underlying molecular mechanisms. Although influenza resistance in inbred mice has been mapped to several quantitative trait loci (QTLs), which have greatly narrowed down the search for host resistance genes, only few underlying genes have been identified.Results: To prioritize a list of promising candidates for future functional investigation, we applied network-based approaches to leverage the information of known resistance genes and the expression profiles contrasting susceptible and resistant mouse strains. The significance of top-ranked genes was supported by different lines of evidence from independent genetic associations, QTL studies, RNA interference (RNAi) screenings, and gene expression analysis. Further data mining on the prioritized genes revealed the functions of two pathways mediated by tumor necrosis factor (TNF): apoptosis and TNF receptor-2 signaling pathways. We suggested that the delicate balance between TNF's pro-survival and apoptotic effects may affect hosts' conditions after influenza virus infection.Conclusions: This study considerably cuts down the list of candidate genes responsible for host resistance to influenza and proposed novel pathways and mechanisms. Our study also demonstrated the efficacy of network-based methods in prioritizing genes for complex traits. © 2013 Bao et al.; licensee BioMed Central Ltd.

Tian X.,University of Hong Kong | Tian X.,HKU Zhejiang Institute of Research and Innovation HKU ZIRI | Lai X.,University of Hong Kong | Lai X.,HKU Zhejiang Institute of Research and Innovation HKU ZIRI | And 5 more authors.
Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences | Year: 2016

Energy is conserved by the first law of thermodynamics; its quality degrades constantly due to entropy generation, by the second law of thermodynamics. It is thus important to examine the entropy generation regarding the way to reduce its magnitude and the limit of entropy generation as time tends to infinity regarding whether it is bounded or not. This work initiates such an analysis with one-dimensional heat conduction. The work not only offers some fundamental insights of universe and its future, but also builds up the relation between the second law of thermodynamics and mathematical inequalities via developing the latter of either new or classical nature. A concise review of entropy is also included for the interest of performing the analysis in this work and the similar analysis for other processes in the future. © 2016 The Author(s) Published by the Royal Society. All rights reserved.

Kong T.,University of Hong Kong | Kong T.,HKU Zhejiang Institute of Research and Innovation HKU ZIRI | Liu Z.,University of Hong Kong | Liu Z.,HKU Shenzhen Institute of Research and Innovation HKU SIRI | And 4 more authors.
Physical Review Applied | Year: 2015

In this work, we study the folding and unfolding of flowing viscous jets by imposing an electric field. We demonstrate that a folded viscous jet can be induced to unfold through jet widening in a sufficiently strong electric field. The folded jets unfold above a critical slenderness, which increases as the jet capillary number increases. Our systematic elucidation of the mechanisms behind the controlled folding has important implications on processes such as nozzle designs for industrial applications that rely on the manipulation of high-speed viscous jets, including liquid dispensing, printing, and food processing. © 2015 American Physical Society.

Zhang Z.,University of Hong Kong | Zhang Z.,HKU Zhejiang Institute of Research and Innovation HKU ZIRI | Xu M.,Shandong Academy of Sciences | Wang L.,University of Hong Kong | Wang L.,HKU Zhejiang Institute of Research and Innovation HKU ZIRI
Journal of Heat Transfer | Year: 2016

The physical vapor transport (PVT) method is widely adopted to produce semiconductor materials including silicon carbide (SiC). This work focuses on the role of thermal radiation for the heat transfer inside the PVT reactor. The radiation is characterized by two dimensionless parameters relating to the SiC charge and to the growth chamber. A simulation program is set up with the finite-volume method (FVM), considering heat generation, conduction, and radiation under the steady-state condition. Comprehensive results are obtained by tuning values of dimensionless parameters and the associated controlling variables, such as the cooling temperature and the coil current density, and illustrated in the phase diagrams. From the study, we find that the charge size has negligible influence on the temperature field, the crucible conduction determines the temperature level, and the relative strength of the chamber radiation against the crucible conduction modifies the temperature field on the SiC ingot. Finally, design guidelines are proposed with the instructive phase diagram to achieve the optimized thermal performance of the PVT reactor. © 2016 by ASME.

Kong T.,University of Hong Kong | Kong T.,HKU Zhejiang Institute of Research and Innovation HKU ZIRI | Liu Z.,University of Hong Kong | Song Y.,University of Hong Kong | And 4 more authors.
Soft Matter | Year: 2013

We investigated the important factors that control the structure of polymeric particles fabricated from emulsion templates. We found that the most energetically stable structure predicted by interfacial energy analysis is not always achieved. The slow dynamics due to an increase in the viscosity of the emulsion phases prevents the polymeric particles from achieving their equilibrium structure. We devised a novel strategy to remove this kinetic barrier, thus achieving the expected equilibrium structure. By considering both the thermodynamic and kinetic aspects during the droplet evolution process, a spectrum of final particle structures can be manipulated in a controlled manner. Our work will enable particle engineering for applications including drug delivery, biomimetic vesicles and photonics. © 2013 The Royal Society of Chemistry.

Yu M.,Shandong Jianzhu University | Fan X.,Shandong Jianzhu University | Walawwe Ranasinghe T.S.B.K.M.,University of Hong Kong | Walawwe Ranasinghe T.S.B.K.M.,HKU Zhejiang Institute of Research and Innovation HKU ZIRI | And 2 more authors.
Advances in Mechanical Engineering | Year: 2015

To understand the effects of liquid morphology on the apparent transfer properties of porous media formed by stacked particles, the authors investigate the particles' aggregation state, apparent volume, thermal conductivity, and electrical conductivity of wet stacked glass beads. It shows that the liquid mainly exists as liquid bridges when the liquid content is low and connects each other when high. The transformation of liquid morphology and distribution influences the liquid effects on particles, thus changing the aggregation state of the particles and the apparent properties of the porous media in turn. A model is developed for predicting the critical liquid content at which the liquid morphology shifts from the state of liquid bridges into the state of interconnectedness. The prediction from the model is in good agreement with the experiment. © The Author(s) 2015.

Bai C.,University of Hong Kong | Bai C.,HKU Zhejiang Institute of Research and Innovation HKU ZIRI | Wang L.,University of Hong Kong | Wang L.,HKU Zhejiang Institute of Research and Innovation HKU ZIRI
International Journal of Heat and Mass Transfer | Year: 2013

The nanofluid configuration is critical for the system performance. Particle material can be configured as dispersed or blade configuration inside the base fluid. This work compares the performance of these two configurations for five heat-conduction systems. The first two systems are heat-transferring and use nanofluids with higher-conductivity particles. The other three systems are heat-insulating and employ nanofluids with lower-conductivity particles. Homogeneous nanofluids with the thermal conductivity of Hashin-Shtrikman bounds are assumed for the dispersed configurations. One single-blade is assumed for the blade configuration. Within the parameter range examined, the performance superiority depends on the system aspect ratio for the heat-transferring systems. For the three heat-insulating systems, the blade configuration always performs better than the dispersed configuration. © 2013 Elsevier Ltd. All rights reserved.

Kong T.,University of Hong Kong | Kong T.,HKU Zhejiang Institute of Research and Innovation HKU ZIRI | Wang L.,University of Hong Kong | Wang L.,HKU Zhejiang Institute of Research and Innovation HKU ZIRI | And 3 more authors.
Soft Matter | Year: 2014

In this work, we have developed a facile, economical microfluidic approach as well as a simple model description to measure and predict the mechanical properties of composite core-shell microparticles made from materials with dramatically different elastic properties. By forcing the particles through a tapered capillary and analyzing their deformation, the shear and compressive moduli can be measured in one single experiment. We have also formulated theoretical models that accurately capture the moduli of the microparticles in both the elastic and the non-linear deformation regimes. Our results show how the moduli of these core-shell structures depend on the material composition of the core-shell microparticles, as well as on their microstructures. The proposed technique and the understanding enabled by it also provide valuable insights into the mechanical behavior of analogous biomaterials, such as liposomes and cells. © 2014 the Partner Organisations.

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