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NSFC/RGC Joint Research Scheme 2015/16 Supported Applications - Layman Summaries of Projects Funded in 2015/16 Exercise

N_CityU102/15
A Micro Array Chip based Single Cell Manipulation System for Characterization of Electrical Stimulation Induced Stem Cell Differentiation

Hong Kong Principal Investigator: Prof Sun Dong (City University of Hong Kong)
Mainland Principal Investigator: Prof Zhu Rong (Tsinghua University)

This proposed project aims to develop a new micro array chip based single cell manipulation system, and apply the system to induce proliferation and differentiation of Mesenchymal Stem Cells (MSCs). The advantage of such a system lies in the capability of manipulating electrical stimulation induced stem cell differentiation as well as characterization of the cell properties at the single cell level to benefit the stimulation parameter screening process. The research will be performed from the three perspectives. First, a single cell manipulation system that integrates micro array chip and robotically controlled optical tweezers will be developed to enable electrical stimulation induced stem cell differentiation. The method will allow groups of cells to be positioned accurately in the electrode for simultaneous processing, with a high degree of repeatability and hence reduce the degree of variability in tests. Second, a new protocol to optimize the stem cell osteogenic differentiation will be designed. Through quantitative analysis using techniques including microwell array chip and robotically controlled optical tweezers for accurate positioning and control of single cells, the stimulation parameters will be optimized and the differentiation efficiency will be much improved. Third, mechanobiological and physiological electrical properties of MSCs will be characterized through single cell stretching manipulation and single cell impedance measurement in situ. Investigation on biological markers will be further performed to evaluate the differentiation for in-vivo testing of the osteogenic potentials of the cells with ectopic bone formation assay.

N_CityU104/15
Non-convex Optimization for Robust Sparse Recovery: Fast Algorithms and Theoretical Analysis

Hong Kong Principal Investigator: Dr So Hing Cheung (City University of Hong Kong)
Mainland Principal Investigator: Dr Gu Yuantao (Tsinghua University)

Sparse recovery refers to extracting a high-dimensional vector with few nonzero entries from a small number of linear measurements. It has been a core topic in various areas of science and engineering including statistics, signal processing, machine learning, information theory, medical imaging and computer vision, because the real-world signals of interest often have a sparse representation in some basis. As an intensive field of research, however, there are obstacles need to be overcome in order to further enhance its practicality. One key issue is to solve large-scale problems in big data analytics where the number of variables is enormous, implying the need of computationally attractive solutions for sparse recovery. Another challenge is to recover the sparse signals from as few observations as possible. A representative example is in magnetic resonance imaging where significant scan time reduction means benefits for patients and health care economics. Furthermore, the development of most existing sparse recovery algorithms assumes that the measurement noise is Gaussian distributed. However, the occurrence of non-Gaussian impulsive noise is in fact common in many applications, and thus these standard solvers may not be able to provide reliable performance in such scenarios. In this research, via exploring advanced signal processing and optimization methods and theories, we propose to utilize possibly non-convex sparsity-inducing and noise-resistant functions in devising efficient and robust algorithms to recover sparse signals in non-Gaussian noise environment with minimum observations. Their fast and distributed realizations will be produced. Moreover, theoretical performance metrics of the developed algorithms, namely, local and global convergence as well as conditions of exact recovery, which are very challenging to analyze in a non-convex setting but are really vital, will be studied. We will also employ the non-convex based sparse recovery methodology to important applications including spectral estimation, source localization, image denoising, magnetic resonance imaging and social network analysis.

N_CUHK404/15
Interactive Attribute Mining and Animated Speech Synthesis for Web-based Spoken Dialog Interactions

Hong Kong Principal Investigator: Prof Meng Helen Mei-ling (The Chinese University of Hong Kong)
Mainland Principal Investigator: Prof Wu Zhiyong (Tsinghua University)

The objective of this project is to develop statistical approaches for natural and expressive speech synthesis for Web-based spoken dialog interactions. We conceive that synthetic speech needs to be much more animated to suit interactions in the ever-proliferating speech-based information services, such as voice search, personal smart phone assistants and Web chatbots or social assistants. The "2012-2013 Annual Report of China's Instant Messaging and User Behavior" states that voice chat has taken more than 50% of the users' instant messaging functions. Human-human spoken interactions are highly expressive, using different intonations, emotions and styles to convey the underlying intent of the message. These proliferating Web information services, (e.g. Apple Siri, Sohu Sogou, Baidu Voice Search, Microsoft's Cortana and Xiaobing, etc.) and Internet social platforms, (e.g. WeChat, Weibo, QQ, Fetion, etc.), call for highly expressive synthetic speech to fulfill the needed user experience (UX) in speech-based interactions. While synthetic speech can achieve a reasonable level of intelligibility and naturalness, the speaking style is primarily constrained to that of read speech and with neutral emotions. Imagine user interactions with a personalized smartphone voice assistant application, such as "Tell me a joke please", "Tell me about romantic dinner venues near here", or "Recite a poem for me please". If the computer can only respond with the neutral style of read speech, the UX will be severely limited. Instead, the spoken response should have a variety of intonations (e.g. declarative, interrogative, exclamatory intonations) and a variety of emotions (e.g. happy, amused, romantic, etc.). Such expressivity calls for relevant interactive styles, depending not only on the information content and dialog context, but also the social context of the interactions. On one hand, the synthesis of expressive speech with different interactive styles to support natural and animated Web-based spoken dialog interactions presents a challenge. On the other hand, the proliferation of these Web-based services generates abundant speech data that avails researchers of a new opportunity - to use data mining and deep learning techniques to discover interactive attributes (including attributes from speech, related text, discourse and social contexts) and model how they govern expressivity in animated speech.

N_HKUST624/15
Single-crystalline silicon cantilever-resonator gas sensor array fabricated using silicon-migration technology for air quality monitoring

Hong Kong Principal Investigator: Prof Wong Man (Hong Kong University of Science and Technology)
Mainland Principal Investigator: Prof Wang Xiao-hong (Tsinghua University)

The objective of the project is to develop a portable and accurate air-quality monitoring system using micro-fabrication technology. Commercially available monitoring systems are inadequate in both accuracy and versatility, detecting only a limited range of pollutants. They are also expensive if imported gas sensing components are used.

The accuracy of a gas sensor can be improved by enhancing the sensitivity of the materials used to detect the pollutants and employing a better transducing mechanism that is more immune to noise and parasitics. These will be accomplished by (1) tailoring the chemical composition of the gas-sensitive material for each target gas and developing nano-porous structures that increase the area in contact with the ambience; and (2) employing silicon-migration technology, a newly developed micro-fabrication technique that is capable of reducing the difficulty in realizing an improved transducing mechanism. A large variety of gases causing air pollution can be detected by integrating an array of such micro-sensors on a micro-chip smaller than a finger-tip.

Given the dire state of air pollution in major cities of the Nation, the availability and deployment of such portable air-quality monitoring system would be welcome by the population. Successful implementation of the project will have significant and long term positive impact on fighting air pollution and enhancing the health of our citizens.

N_PolyU502/15
Reversal of P-gp-mediated Paclitaxel Resistance: Identification of Modulator-binding Site on P-gp and Rational Design of Next Generation P-gp Modulators

Hong Kong Principal Investigator: Prof Chow Ming-cheung (The Hong Kong Polytechnic University)
Mainland Principal Investigator: Prof Sun Yan (Tianjin University)

Paclitaxel is a highly effective anti-cancer drug but its use is limited to intravenous administration only; causing unnecessary pain, extra cost of hospitalization and limiting its use to only those with access to hospitals. The low oral bioavailability of paclitaxel is due to the active efflux of paclitaxel by an ATP-binding cassette transporter (P-gp) located in enterocytes. The use of paclitaxel is further limited by the emergence of multidrug resistant (MDR) cancer cells which overexpresses P-gp to reduce intracellular paclitaxel level.

An effective P-gp inhibitor can help to improve oral bioavailability of paclitaxel and to reverse P-gp-mediated paclitaxel resistance. We have demonstrated that synthetic flavonoid derivatives represent a new class of highly potent and safe P-gp inhibitor which can both increase oral bioavailability of paclitaxel as well as reversing paclitaxel resistance in vitro and in vivo.

In this project, we will develop a mass-spectrometry method (Hong Kong team) to identify the exact binding site of flavonoid derivatives on P-gp. We will focus on the binding site and use molecular dynamic simulation and docking approach to determine how flavonoid derivatives and paclitaxel bind to P-gp (Tianjin team). Based on the binding information, we will design new flavonoid derivatives that can bind tighter to P-gp and use the newly-designed compounds to test their ability in improving oral bioavailability of paclitaxel and in reversing paclitaxel resistance. (Hong Kong and Tianjin team).

In summary, this project will combine biochemistry, molecular simulation, synthetic chemistry, pharmacokinetics and xenograft study to develop the next generation of flavonoid derivatives to further improve the oral bioavailability of paclitaxel and to reverse paclitaxel resistance in cancer.

N_HKUST625/15
Functional and in vivo study of the Neuroligin and Itch Interaction

Hong Kong Principal Investigator: Prof Xia Jun (Hong Kong University of Science and Technology)
Mainland Principal Investigator: Prof Luo Jianhong (Zhejiang University)

Human brain is made of billions of neurons. Neurons communicate with each other via specialized structures called synapse. Synapses are important for neuronal communication and information processing in the brain. Formation of synapses, or synaptogenesis, ensures the proper wiring of neuronal circuitry in the brain. Abnormal synaptogenesis is believed to be the underlying cause of brain disorders such as autism and mental retardation. The process of synapse formation is tightly controlled, but the molecular mechanism underlying this process is not fully understood. In this study, we aim to investigate the roles of two molecules, neuroligin and Itch, to elucidate their functions in synapse formation and help us understand the molecular mechanism of synaptogenesis.

N_HKU732/15
Neurodevelopmental effect of gene-environment interaction among early-onset schizophrenia patients: a combined genetic and neuroimaging approach

Hong Kong Principal Investigator: Prof Chen Eric Yu Hai (The University of Hong Kong)
Mainland Principal Investigator: Prof Liu Zhening (The Second Xiangya Hospital Central South University)

Schizophrenia is a chronic and disabling psychiatric disorder of partial genetic aetiology, affecting approximately 1% of the population worldwide. Genetic studies have made major advances in the aetiology of schizophrenia; the Psychiatric Genetics Consortium has recently identified 108 common variants of small effects, which in aggregate account for nearly 30% of the population variance in liability. However, little is known about how these risk genes affect the brain and the psychopathological mechanisms involved. One particularly promising approach is to investigate the gene-environment interaction of schizophrenia risk gene in the Han Chinese population, which will combine genetic and neuroimaging approach to shed light on the pathophysiological processes that underlie schizophrenia which are likely to bridge the gap in genetic study and have a much bigger impact. Understanding how the disruption of these genes increases the risk of schizophrenia has the potential to uncover novel therapeutic targets for the treatment of schizophrenia. New treatments acting through alternative mechanisms are urgently needed, as all current antipsychotic drugs act via dopamine receptors, and are effective only in reducing positive symptoms, leaving substantial residual negative symptoms and cognitive deficits which severely limit social and occupational functions. This study will recruit 300 Han Chinese case-sibling-healthy control trios (total 150 participants from China and Hong Kong each), in order to uncover the underlying mechanisms involved in schizophrenia. This will be among the first to systematically investigate the gene-environment interaction that confer increased risk to schizophrenia in the Han Chinese population.

N_HKU740/15
Development of DNA-encoded DNA-glycan constructs as multivalent influenza hemagglutinin inhibitors

Hong Kong Principal Investigator: Dr Li Xuechen (The University of Hong Kong)
Mainland Principal Investigator: Dr Li Xiaoyu (Peking University)

(Project withdrawn)

N_HKU713/15
A comprehensive functional ultrasound imaging framework: the assessment of vascular mechanics for the diagnosis of cardiovascular diseases

Hong Kong Principal Investigator: Dr Lee Wei Ning (The University of Hong Kong)
Mainland Principal Investigator: Dr Luo Jianwen (Tsinghua University)

Cardiovascular diseases (CVDs) remain to claim the majority of annual global deaths. The rupture of atherosclerotic plaques is known to be a primary trigger of cardiovascular events, such as stroke. Reliable noninvasive imaging methods are thus urgently needed not only for the effective detection of vascular pathological changes, but also because they may enable the prognosis of CVDs for timely interventions. Medical ultrasound examinations remain predominant in clinic practice for the assessment of vascular function because it is inexpensive, portable, and more compatible with subjects, and in particular, provides superior real-time feedback of morphology, dimensions, and hemodynamics of the artery. Beyond the aforementioned conventional diagnostic indices, arterial stiffness alteration has been found to be a potential indicator of plaque vulnerability, but their direct relationship has not been established because of the lack of an imaging framework that gives full access to vascular mechanics. In this project, we therefore aim to develop a comprehensive ultrasound imaging framework that quantifies and maps the arterial mechanical behavior in full aspects for 1) accurate risk assessment of atherosclerotic plaque rupture, 2) better understanding of vascular disease progression, and 3) personalized computational modeling of the artery.

N_HKU707/15
Advancing Transportation Systems Analysis by Integrating Safety Evaluation

Hong Kong Principal Investigator: Prof Wong Sze Chun (The University of Hong Kong)
Mainland Principal Investigator: Prof Huang Helai (Central South University)

The traditional theoretical framework of transportation system analysis (TSA) based on the interactions of travel demand, transportation supply, and social activities focuses primarily on evaluating and optimizing transportation efficiency. As decisions concerning transportation planning and engineering and travel-demand management and policy can exert significant effects on traffic safety, safety should be incorporated into the TSA process. We propose a proactive, system-wide and quantitative approach to preventing crash occurrences through the integration of safety evaluation into TSA with the ultimate aim of establishing inherently safe transportation networks. Our aims are to (1) establish quantitative safety assessment methods that integrate safety evaluation into traditional transportation system identification, trip behavior modeling, and supply-demand equilibrium theory; (2) develop a transportation network-level safety performance function using Bayesian spatiotemporal and hierarchical modeling techniques in which a variety of factors related to the regional road network, road entities, traffic flow, and human-vehicle systems are accounted for; and (3) upgrade TSA methodology with the integrated objective of both transportation efficiency and traffic safety to strengthen decision-making optimization theory. For the purpose of methodological demonstration and evaluation, case studies will be conducted on the transportation networks of three regions: (1) Hong Kong, a highly developed urban region; (2) Hillsborough County, Florida, in the U.S., which comprises a mixture of urban and suburban areas; and (3) the urban agglomeration of Changsha-Zhuzhou-Xiangtan in China's Hunan province, a developing region comprising linked cities, an intercity highway system, an urban road system, and suburban/rural areas. Drawing on the research achievements of the project's mainland team in traffic safety and the expertise of the Hong Kong team in TSA, the proposed project is expected to produce a new generation of TSA methods.

N_CUHK418/15
Investigation of characteristics and mechanism of earthquakes associated with the Hutubi gas reservoir

Hong Kong Principal Investigator: Prof Wong Teng-fong (The Chinese University of Hong Kong)
Mainland Principal Investigator: Prof Wang Baoshan (Institute of Geophysics, China Earthquake Administration)

Earthquakes have caused significant damage and casualty in human history. Appropriate societal responses for reducing the risk of major earthquakes can be formulated only if there is a fundamental understanding of the physics of this natural hazard. In recent decades, there is also heightened concern that anthropogenic processes can induce seismicity and trigger relatively large quakes. Notwithstanding the extensive occurrence of induced seismicity in a diversity of geologic settings, many critical questions regarding these intriguing phenomena remain unanswered, and consequently controversy has emerged regarding a number of recent earthquakes, as to whether they had indeed been triggered by human activities. This is a proposal to tackle these questions by conducting a comprehensive interdisciplinary investigation on earthquakes near the Hutubi gas reservoir (HGR), Xinjiang, the largest underground repository for natural gas in China.

The HGR is one of the key facilities of the "West-East Gas Pipeline Project", and plays a critical role in the strategic cooperative framework of "One Belt and One Road". Following the injection initiated in 2013, a sequence of earthquakes occurred in the vicinity of the HGR, with the largest magnitude of ML 3.5. Whether these earthquakes were induced by the gas injection, and if so, whether the cyclic injection/extraction may cause more damaging earthquakes are critical questions that must be addressed for assessment of seismic hazard of this facility. While focusing on seismicity in this location, the overarching goal of this proposal is to conduct a systematic investigation of the HGR as a natural laboratory and advance our understanding of earthquake physics and mechanisms of induced seismicity, so as to mitigate potential risks associated with the development of such geologic repositories.

Our methodology is based on the premise that it is necessary to conduct integrated seismological, geodetic, and laboratory measurements, before one can move on to construct a realistic geomechanical model that can tackle the bigger question whether and how such an anthropogenic process may trigger potentially damaging earthquakes. We will first deploy a seismic network and then derive precise location and reliable focal mechanisms of the local earthquakes. We will also undertake a systematic geodetic analysis by integrating Interferometric Synthetic Aperture Radar and Global Positioning System data to measure the surface deformation associated with cyclic gas injections. Guided by laboratory measurement of the rock physics properties, we will develop a 3D geomechanical model with quantitative constraints from the seismological and geodetic data.

N_HKUST609/15
Stoichiometric dynamics of carbon and nitrogen in two major hypoxia zones of Chinese coastal water

Hong Kong Principal Investigator: Dr Liu Hongbin (Hong Kong University of Science and Technology)
Mainland Principal Investigator: Dr Kao Shuh-Ji (Xiamen University)

Like the carbon cycle, the nitrogen cycle is an important part of every ecosystems. The ocean's nitrogen cycle contains many pathways involving various microbes. Many of these processes are regulated by oxygen concentrations in the water column and sediment, and some of them produce nitrous oxide (N2O), a greenhouse gas. Coastal eutrophication, fuelled by increasing anthropogenic nutrient input, results in oxygen depletion in bottom water (called hypoxia or "dead zone"), causing detrimental ecological impact on the communities in the affected waters. Because the hypoxic condition promotes anaerobic metabolic processes, such as anaerobic ammonium oxidation (anammox) and denitrification, the hypoxic zones may play an important role in global N balance, but the relative roles of anaerobic processes are not well understood and are currently a subject of controversy.

In this project, we will apply two very powerful techniques to study the microbial nitrogen metabolism in both the water column and sediments: stable isotope to track and quantify different metabolic pathways and next generation high-throughput sequencing to identify the genes and microbial organisms that are performing the functions. We will conduct our study in the oxygen-depleted zones adjacent to Changjiang estuary and Pearl River estuary. We will study the microorganisms that are responsible for specific N pathways, and quantify their functional activity under different environmental conditions. We will attempt to determine the activity of individual nitrogen transformation processes that account for the production of greenhouse gasses in oxygen-depleted coastal hypoxic zones. We will also explore the controlling factor and specific stoichiometric linkage between C and N for each individual transformation process in a nitrogen reaction web. Genetic information, together with rate measurements, will allow us to better understand the dynamics and complexity of the nitrogen cycle in the hypoxic condition, and their contribution to the global nitrogen budget.
An increasing ocean temperature due to climate change also decreases oxygen solubility and increases thermal stratification of the water column, worsening the hypoxic condition to worsen in the coastal zones around the world. That may lead to enhanced nitrogen cycling, particularly anaerobic processes, resulting in the loss of bioactive nitrogen and the emission of greenhouse gases, such as N2O and CH4. Our study will shed light on nitrogen and carbon cycles in oxygen-depleted marine environments, which could have significant implications on the global nitrogen cycle and climate change.

N_HKU718/15
Mechanistic study of the degradation of multiple indoor air pollutants through Vacuum UV photocatalysis

Hong Kong Principal Investigator: Prof Leung Yiu Cheong (The University of Hong Kong)
Mainland Principal Investigator: Dr Huang Hai Bao (SunYat-sen University)


Vacuum ultraviolet (VUV) light produces a great enhancement on the photocatalytic degradation of indoor air pollutants and pathogenic bacterial contaminants over traditional PCO process. VUV photocatalytic oxidation technology presents an efficient and highly promising technology for the purification of indoor air pollutants due to the coexistence and synergetic effect of VUV photolysis, PCO and catalytic ozonation during the process. However, the whole process is mainly contributed by the high energy UV photolysis while the contribution from photocatalytic oxidation process is so small that their capability has not been fully utilized yet. Furthermore, ozone, a strong oxidant, will be generated that can be used to enhance the degradation of pollutants. The residual ozone needs to be purified before discharging while traditional catalysts have poor capacity for ozone decomposition. The abovementioned problems are the bottleneck and constraints for further development and application of this technology, which we want to tackle in this study. Based on the traditional photocatalysis process and our preliminary study on the VUV photocatalysis, this project proposed to adopt the VUV photocatalysis process, making use of the synergetic effect of the photolysis, photocatalysis and ozonation reactions, for the degradation of multiple indoor air pollutants. Multi-functional mesoporous TiO2 photocatalysts will be prepared and modified with transition metals to improve its capabilities for the elimination and utilization of residual ozone as well as to enhance its photocatalytic oxidation capability. The purification performance and structural characteristics of the catalysts developed will be studied thoroughly. In particular, the mechanism of the complex air pollutant transformation route and its synergetic effects with other processes (such as ozonation and photolysis) will be focused. The main objective of this research is to investigate the key scientific questions related to the degradation of indoor air pollutants and bacteria by the VUV photocatalysis technology. This will enhance the future development of the technology and has a long term impact on the indoor air quality and our health.

N_CityU113/15
Fluorescent Organic Compound-Phosphorescent Inorganic Transition Metal Complex Conjugates as Bioprobes and Imaging Reagents

Hong Kong Principal Investigator: Prof Lo Kenneth Kam-Wing (City University of Hong Kong)
Mainland Principal Investigator: Prof Yu Cong (Changchun Institute of Applied Chemistry, Chinese Academy of Sciences)

This project aims to develop novel conjugates composed of fluorescent perylene and phosphorescent transition metal complexes as bioprobes and imaging reagents. Perylene and its derivatives are known to display high photochemical stability and intense fluorescence. Although perylene derivatives modified with polar and charged substituents display enhanced water solubility, they still have a high tendency to form non-emissive aggregates in aqueous solution when they are brought together by macromolecules of the opposite charge. The interplay between the non-emissive aggregated form and strongly fluorescent monomeric form has inspired the development of sensitive and selective bioassays. Recently, there has been an emerging interest in the cellular uptake, cytotoxic activity, and bioimaging applications of phosphorescent transition metal complexes. In this project, we will develop conjugates composed of fluorescent perylene and phosphorescent transition metal complexes. The lipophilicity, aggregation behavior, and photophysical and photochemical properties of these conjugates will be studied. Additionally, their cytotoxicity and cellular uptake will be investigated by bioassays, inductively-coupled plasma mass spectrometry, flow cytometry, and laser-scanning confocal microscopy. We anticipate that the aggregation-dependent fluorescence of perylene and the environment-sensitive phosphorescence of transition metal complexes will cause our target conjugates to exhibit brand new emission characteristics, which will contribute to the development of new cellular reagents with useful diagnostic applications.

N_CityU123/15
Synthesis and Optoelectronic Properties of the White Graphene

Hong Kong Principal Investigator: Dr Zhi Chunyi (City University of Hong Kong)
Mainland Principal Investigator: Prof Zeng Haibo (Nanjing University of Science and Technology)

Hexagonal boron nitride (h-BN) crystal is a layer-structured direct band gap material with a morphology-independent constant wide energy gap of >6.0 eV. This makes it very suitable for many ultra-violet optoelectronic applications. In addition, it has outstanding mechanical properties, ultra-high thermal conductivity and tuneable electrical properties, as well as excellent chemical stability, good resistance to corrosion and very high structurally stability etc. The layered structure of h-BN make it possible to exfoliate it to be a perfect 2D crystal, facilitating its processing and utilization for applications.

Quantum dots are small-sized semiconductors whose electronic characteristics are closely related to the size and shape of the individual crystal. Generally, the smaller the size of the crystal, the larger the band gap, the greater the difference in energy between the highest valence band and the lowest conduction band becomes. By fabricating quantum dots, the band gap of the semiconductors can be tuned and some surface chemical status can be activated to dominate the properties of the extremely small crystals.

Keeping in mind excellent overall properties and the wide band gap of h-BN material, the white graphene (two-dimensional h-BN crystal) and white graphene quantum dots (two-dimensional h-BN crystal with small lateral sizes) might possess very promising optoelectronic applications working in deep ultraviolet wavelength range. However, so far, related explorations have not been carried out due to many difficulties in fabrication of white graphene and its quantum dots.

In recent years, the great progresses in two-dimensional materials study have promote research on exfoliating h-BN and fabricating its quantum dots. Continuously improved sample quality and quantity make it possible to work on their applications. This project is designed to develop methods for synthesis of mono-dispersed size controllable white graphene and white graphene quantum dots, as well as their modification approaches for deep ultraviolet optoelectronic applications.

N_CUHK415/15
Visible-light optomechanical integrated circuits based on III-nitride semiconductors

Hong Kong Principal Investigator: Prof Sun Xiankai (The Chinese University of Hong Kong)
Mainland Principal Investigator: Prof Wang Lai (Tsinghua University)

This proposal aims to develop optomechanical integrated circuits based on III-nitride semiconductors for visible-light operation, in order to enhance the coupling between optical and mechanical degrees of freedom in nanomechanical structures for the ultimate device miniaturization and on-chip integration.

A subject with long history, mechanics studies the behavior of physical bodies when subjected to forces or displacements. With the development of nanotechnologies, people have gained the capabilities to create and control such physical bodies (so-called mechanical resonators) at the nanoscale for precision measurements of force, mass, and displacement. The mechanical information of microscopic objects was originally accessed electronically based on the direct electromechanical coupling. However, the electrical methods suffer from low sensitivity and limited operational bandwidth. Recently, mechanical actuation and detection by using optomechanical coupling have attracted intense interest because of the ultimate detection sensitivity, which is limited only by quantum mechanics, and unlimited operational bandwidth. With the mature platforms of nanophotonics and nanoelectromechanics, optomechanical integrated circuits (OMICs) were developed to integrate photonic components and nanomechanical resonators on a single chip for strong optomechanical coupling. However, the operational light has so far remained in the communication band (wavelength ~1550 nm), which is currently the bottleneck for further device downsize because the fundamental optical diffraction limit does not allow efficient guidance of optical mode below the size of optical wavelength.

Here we propose to revolutionize nano-optomechanics by developing OMICs that operate in the visible wavelength range (~460 nm) with wide-bandgap III-nitride semiconductors. Such an OMIC consists of a one-dimensional optomechanical crystal cavity as the optomechanical resonator and other photonic components for fiber-to-chip coupling, on-chip light routing, modulation, and detection. The III-nitrides as optically active materials also provide the possibility to integrate a laser diode with the OMIC on the same platform.

This proposal has great significance to both fundamental physics and practical applications: Reducing the operational light wavelength by ~3.4 times enables smaller optomechanical resonators with mass reduced by up to ~40 times and mechanical resonant frequency enhanced by up to ~6.3 times without loss of the strong optomechanical coupling. Such performance enhancement is particularly useful for ground-state cooling, mass sensing, RF/microwave optoelectronic oscillating, and signal processing applications. Moreover, the possibility of monolithic integration of a laser diode with an OMIC enables an ultracompact nanomechanical sensor with only electronics interfacing with the outside world and possessing the ultimate sensitivity owing to the on-chip light generation and optomechanical interaction.

N_PolyU517/15
Microengineering Organic Semiconductor Materials for Flexible OTFT Devices

Hong Kong Principal Investigator: Dr Zhang Aping (The Hong Kong Polytechnic University)
Mainland Principal Investigator: Prof Zheng Qingdong (State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences)

New materials have become one of the crucial forces driving technology development and innovation. One remarkable recent material development is in the field of organic thin-film transistors (OTFTs). Recent researches have demonstrated that the performance of organic field-effect transistors (OFETs) has surpassed that of amorphous silicon transistors in terms of field-effect mobilities and on-off ratios, and is approaching that of polycrystalline silicon. Therefore, it paves new ways for the development of novel optoelectronic devices and opens up new applications.

In order to exploit and commercialize organic semiconductors, one needs a practical fabrication approach to produce organic semiconductor devices with reasonable throughput. Inkjet printing, stamping, shadow-mask patterning, and photolithography technologies have been employed to fabricate organic semiconductor devices. Photolithography uses light to transfer patterns from photomasks to photoresist on wafer, has been the workhorse for semiconductors over 50 years. Compared with other technologies, it has the advantages of both high resolution and high throughput. The crux of the problem is to develop a suitable photolithography technology using high-performance organic semiconductors for fabrication of new flexible optoelectronic devices.

An emerging and revolutionary photolithography technology is the maskless lithography. Analogous to the use of memory stick to replace film in digital camera, maskless lithography does not require photomask, instead it employs a high-speed spatial light modulator, with a million micron-size mirrors, for pattern generation. Most important, it is particular suitable for fabrication of flexible devices because of its real-time imaging and dynamic pattern generation features enable compensation of in-plane deformations induced by substrate expansion/shrinkage or moisture uptakes during the process. The aim of this proposed project is to fuse this new lithography technology with organic semiconductor materials to develop new flexible electronic devices. In particular, we will: 1) develop new organic semiconductor materials for high-performance OFETs; 2) develop new maskless lithography technology for patterning organic semiconductors; 3) develop large-area flexible tactile sensors based on high-density OFET array.

The successful outcomes of this project will bridge the researches on new materials and advanced lithography technologies to develop new flexible OTFT devices. The processes to be developed in the project could bring forth new approaches to fabricate novel devices for sensors, organic solar cells, organic light-emitting diodes, large-area rollable displays, etc.

N_HKUST601/15
Detect Electroluminescence of Single Conjugated Polymers

Hong Kong Principal Investigator: Prof Lin Nian (Hong Kong University of Science and Technology)
Mainland Principal Investigator: Prof Liu Pei Nian (East China University of Science and Technology)

Organic light-emitting diodes (OLEDs) are widely used in television screens, computer monitors, mobile phones for displays as well as in solid-state light sources. Investigating the light emission at the single-molecule level is highly desirable since such studies may shed light on the single-molecule mechanism of OLEDs. In this project, we will employ on-surface polymerization to synthesize polymers containing light-emitting functional groups, and systematically investigate the electroluminescence occurring in the single polymers.

N_HKU710/15
Photonic Integration in GaN Membranes on Silicon

Hong Kong Principal Investigator: Dr Choi Hoi Wai (The University of Hong Kong)
Mainland Principal Investigator: Prof Wang Yongjin (Nanjing University of Posts and Telecommunications)

Half century since the invention of the visible light-emitting diode (LED), the technology has blossomed from a minuscule light emitter to present-day powerful illuminators, driven by explosive developments in material and processing technologies, including but not limited to advanced epitaxy of complex quantum structures, nanotechnology-enabled devices and sophisticated chip packaging techniques to accommodate the needs of such avant-garde devices. Today LEDs are part of everyday lives, appearing as traffic lights, LCD backlights, desktop lamps, handheld torches just to name a few. Of course LEDs are not limited to domestic uses; devices of specific wavelengths are adopted in professional products such as phototherapy, biotechnology, medical imaging, and microscopy owing to their distinct optical emission characteristics not found from any other light sources. However, there is one application of LEDs that have not been fully explored: as emitters in photonic systems. Such roles have conventionally been fulfilled by laser sources due to issues of optical coupling between LEDs and other photonic components.

The photonic circuit concept has been introduced in recent years, whereby different photonic components of different functions are monolithically integrated onto a single chip. In this ambitious yet fully realizable project we attempt to integrate LEDs with waveguides and photodetectors to build a highly-integrated photonic system to perform functionalities including optical communications, based on the GaN-on-Si platform. This is possible due to the fact that the GaN materials play the three functions of light emission, transmission and detector simultaneously, and most importantly, equally well. At the same time, the Si substrate can readily be removed for the formation of highly-confining waveguides. Therefore, the outcomes of this project will pave the way towards next-generation photonic chips based on the GaN materials.

N_CityU128/15
Characterization and Control of a System with Multiple Offshore Power Inverters Connected in Parallel with Long Cables

Hong Kong Principal Investigator: Prof Chung Henry Shu Hung (City University of Hong Kong)
Mainland Principal Investigator: Prof Wu Weimin (Shanghai Maritime University)

An emerging trend in the electricity industry is a paradigm shift from large-scale centralized power plant to small-scale distributed energy resources (DERs) located at the point of utilization. Regardless of the type of DER, inverters, which convert DC into AC power, are crucial devices for injecting generated energy into the macro-grid. In order to offer a high degree of modularity, scalability, adaptability, maintainability, and autonomic behavior, it is more advantageous to use multiple low-power parallel-connected inverters than a single high-power inverter unit. In many applications, such as small-scale wind farms and wave generator systems, those low-power inverters are connected together through long cables. Due to possible mismatch among the output impedances of the inverters, cable characteristic impedance, load characteristics, and grid impedance, the entire system could be dynamically unstable. Furthermore, high-order output filters exhibit multiple resonant frequencies that would cause output oscillation. An existing remedial measure to alleviate this problem is to apply a passive damper in the power stage or an active damping technique in the controller, but they would cause either extra power loss or limit the system dynamics.

This project aims to enable a breakthrough in multi-parallel-connected inverter technology by investigating 1) interactions among the inverters, cables, loads, and power grid, 2) predictive control algorithms for controlling active and reactive power flow, 3) an active damping technology at the point of common coupling, and 4) a fault diagnosis technique for DERs. The findings will lay foundation and research directions for new-generation inverters to 1) regulate the power flow to the grid and the voltage at the interface independent of the value of the transmission line impedance, and 2) pickup up appropriate share of load in a rapid and seamless fashion when any inverter islands from or reconnects to the power grid, and the system to 3) keep the operation stable under normal condition, and 4) automatically detect and isolate the system from any fault or abnormal condition.

N_CUHK437/15
Experimental Studies of Geometrical Properties, Vorticity Dynamics and Small-Scale Statistics of Vortex Structures in Rotating Thermal Convection

Hong Kong Principal Investigator: Prof Xia Keqing (The Chinese University of Hong Kong)
Mainland Principal Investigator: Prof Zhong Jinqiang (Tongji University)

Turbulent convections subject to a background rotation are ubiquitous in nature and in engineering. Understanding the fundamental aspects of rotation on convective flows is not only of scientific interest but also of great importance for real-life applications. Rotating Rayleigh-B?nard (RB) convection is an idealized model for studying the basic physics involved in the general rotating convection phenomena. One characteristic flow structure in rotating RB convection is the vertically aligned vortex. The changes in its morphology and dynamics have been suggested to be responsible for the change in heat transport properties and thus determine the multiple transitions among different flow regimes, which is a key issue in the study of rotating turbulent convection. Despite its importance, the statistical properties of the vortex structures have been rarely studied, especially experimentally. The scarcity of works concerning the geometrical and dynamical properties of the vortex structures in rotating RB convection has prompted the proposed investigation.

In the proposed project, we will carry out a series of experiments to systematically investigate the geometrical properties and vorticity dynamics of the vortex structures in rotating RB convection, the latter of which has never been measured experimentally. Moreover, we will study the small-scale properties both inside and outside the vortex structures, which has received little attention so far. These results will not only provide us a comprehensive understanding of the vortex structures in rotating RB convection, but will also offer new approaches to understand the flow regime transitions in this system. We expect the outcomes of this study to enrich our existing knowledge of the vortex structures in rotating thermal turbulence, which exist widely in various rotating convective phenomena in nature and in technical applications.

N_HKUST603/15
Design, synthesis and application of fused osmacycles/iridacycles containing main group heteroatoms

Hong Kong Principal Investigator: Prof Lin Zhenyang (Hong Kong University of Science and Technology)
Mainland Principal Investigator: Prof Xia Haiping (Xiamen University)

Metal-containing conjugate heterocycles are species in which a CH unit in a conjugate heterocycle is replaced by a metal fragment. Because of the extensive delocalization inherited from the heterocycles, they are expected to display rich physical properties for various applications in materials chemistry. In this joint NSFC/RGC joint proposal, we here plan to investigate both computationally and experimentally how the synthesis of fused osmacycles/iridacycles with main group heteroatom can be achieved and how the electronic characteristics of these organometallic heterocycles can be altered while maintaining the structural features.

N_HKUST620/15
Highly parallel algorithms for fluid-structure interaction problems and applications

Hong Kong Principal Investigator: Prof Wang Xiao-Ping (Hong Kong University of Science and Technology)
Mainland Principal Investigator: Prof Cai Xiao-Chuan (Chinese Academy of Sciences)

Numerical simulation based on the solution of fluid-structure interaction (FSI) problems plays an increasingly important role in medical applications, such as surgical planning of an artery bypass. Existing techniques and software packages were developed years ago for computers with limited computing power in terms of the memory capacity and processing speed and with many overly simplified mathematical assumptions. In this project, we propose to develop high performance software that is more suitable for today's supercomputers with tens of thousands of processor cores and based on more accurate models.