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Cracking Epigenetic Inheritance: HKU Biologists Discovered the Secrets of How Gene Traits are Passed on

A research team led by Professor Yuanliang ZHAI at the School of Biological Sciences, The University of Hong Kong (HKU) collaborating  with Professor Ning GAO and Professor Qing LI from Peking University (PKU), as well as Professor Bik-Kwoon TYE from Cornell University, has recently made a significant breakthrough in understanding how the DNA copying machine helps pass on epigenetic information to maintain gene traits at each cell division. Understanding how this coupled mechanism could lead to new treatments for cancer and other epigenetic diseases by targeting specific changes in gene activity. Their findings have recently been published in Nature. Background of the Research Our bodies are composed of many differentiated cell types. Genetic information is stored within our DNA which serves as a blueprint guiding the functions and development of our cells. However, not all parts of our DNA are active at all times. In fact, every cell type in our body contains the same DNA, but only specific portions are active, leading to distinct cellular functions. For example, identical twins share nearly identical genetic material but exhibit variations in physical characteristics, behaviours and disease susceptibility due to the influence of epigenetics. Epigenetics functions as a set of molecular switches that can turn genes on or off without altering the DNA sequence. These switches are influenced by various environmental factors, such as nutrition, stress, lifestyle, and environmental exposures. In our cells, DNA is organised into chromatin. The nucleosome forms a fundamental repeating unit of chromatin. Each nucleosome consists of approximately 147 base pairs of DNA wrapped around a histone octamer which is composed of two H2A-H2B dimers and one H3-H4 tetramer. During DNA replication, parental nucleosomes carrying the epigenetic tags, also known as histone modifications, are dismantled and recycled, ensuring the accurate transfer of epigenetic information to new cells during cell division. Errors in this process can alter the epigenetic landscape, gene expression and cell identity, with potential implications for cancer and ageing. Despite extensive research, the molecular mechanism by which epigenetic information is passed down through the DNA copying machine, called the replisome, remains unclear. This knowledge gap is primarily due to the absence of detailed structures that capture the replisome in action when transferring parental histones with epigenetic tags. Studying the process is challenging because of the fast-paced nature of chromatin replication, as it involves rapid disruption and restoration of nucleosomes to keep up with the swift DNA synthesis. In previous studies, the research team made significant progress in understanding the DNA copying mechanism, including determining the structures of various replication complexes. These findings laid a solid foundation for the current research on the dynamic process of chromatin duplication. Summary of Research Findings This time, the team achieved another breakthrough by successfully capturing a key snapshot of parental histone transfer at the replication fork. They purified endogenous replisome complexes from early-S-phase yeast cells on a large scale and utilised cryo-electron microscopy (cryo-EM) for visualisation. They found that a chaperone complex FACT (consisting of Spt16 and Pob3) interacts with parental histones at the front of the replisome during the replication process. Notably, they observed that Spt16, a component of FACT, captures the histones that have been completely stripped off the duplex DNA from the parental nucleosome. The evicted histones are preserved as a hexamer, with one H2A-H2B dimer missing. Another protein that involved in DNA replication, Mcm2, takes the place of the missing H2A-H2B dimer on the vacant site of the parental histones, placing the FACT-histone complex onto  the front bumper of the replisome engine, called Tof1. This strategic positioning of histone hexamer on Tof1 by Mcm2 facilitates the subsequent transfer of parental histones to the newly synthesised DNA strands. These findings provide crucial insights into the mechanism that regulates parental histone recycling by the replisome to ensure the faithful propagation of epigenetic information at each cell division. This study, led by Professor Zhai, involved a collaborative effort that  spanned nearly eight years, starting at HKUST and concluding at HKU. He expressed his excitement about the findings, ‘It only took us less than four months from submission to Nature magazine to the acceptance of our manuscript. The results are incredibly beautiful. Our cryo-EM structures offer the first visual glimpse into how the DNA copying machine and FACT collaborate to transfer parental histone at the replication fork during DNA replication. This knowledge is crucial for elucidating how epigenetic information is faithfully maintained and passed on to subsequent generations. But, there is still much to learn. As we venture into uncharted  territory, each new development in this field will represent a big step forward for the study of epigenetic inheritance.’ The implications of this research extend beyond understanding epigenetic inheritance. Scientists can now explore gene expression regulation, development, and disease with greater depth. Moreover, this breakthrough opens up possibilities for targeted therapeutic interventions and innovative strategies to modulate epigenetic modifications for cancer treatment. As the scientific community delves deeper into the world of epigenetics, this study represents a major step towards unravelling the complexities of replication-coupled histone recycling. The cryo-EM structure of the yeast replisome in complex with FACT and parental histones (A) and its atomic model (B). Modified from Li et al, Nature (2024)   The evicted histone hexamer and its chaperons from the replisome structure. (A-B) The architecture of the parental histone hexamer. (C-D) The histone-chaperone complex on the replisome. (E-F) The structure of an intact nucleosome. Modified from Li et al, Nature (2024)   About the Research Team Apart from Professor Yuanliang Zhai’s lab, the research team also includes Professor Xiang David Li from Department of Chemistry of HKU, Professor Yang Liu and Professor Keda Zhou from School of Biomedical Sciences of HKU, Professor Shangyu Dang from Division of Life Science of HKUST, and others. Learn more about Professor Yuanliang Zhai’s work and his research team: https://www.scifac.hku.hk/people/zhai-yuanliang or https://zhai95.wixsite.com/mysite-1 Co-authors include Mr Yuan Gao, Mr Jian Li, Dr Zhichun Xu from School of Biological Sciences (SBS) of HKU; Dr Ningning Li, Ms Yujie Zhang, Dr Jianxun Feng from School of Life Sciences of PKU, Dr Daqi Yu and Dr Jianwei Lin from Department of Chemistry of HKU, and Dr Yingyi ZHANG from Biological Cryo- EM Center of HKUST. The journal paper can be accessed here. 

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PhD Student Won Best Talk Award at AsiaEvo Conference for Research on Germline Mutation Rates in Sticklebacks

PhD student Chaowei Charlene ZHANG from the School of Biological Sciences was honored with the Best Talk award at the Third AsiaEvo Conference held in December 2023 at the National University of Singapore. She won the award by presenting her research paper titled 'Pedigree-based Germline Mutation Rate in Sticklebacks,' which shed light on the significance of accurately estimating mutation rates in genetics. Her findings served as a valuable resource for researchers studying fish population genetics, especially in the context of sticklebacks. This research has been published in Molecular Biology and Evolution in Issue 9, Volume 40. The AsiaEvo Conference aims to provide a platform for evolutionary researchers from Asian countries, enabling them to present their work and engage in meaningful discussions. Additionally, the conference seeks to foster international collaboration in the field of evolutionary biology, enhance the understanding and application of evolutionary thinking in Asia, and inspire talented students to pursue studies in evolutionary science. Charlene is currently supervised by Professor Juha MERILÄ in the Area of Ecology and Biodiversity.

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Biological Sciences PhD Graduate Awarded Prestigious Grant by Malacological Society of London in 2023

PhD graduate Dr Bovern ARROMRAK from the School of Biological Sciences was awarded the Early-Career Research Grant by the Malacological Society of London in 2023. This highly competitive grant is conferred on students and researchers who have demonstrated exceptional potential and achievements in their respective fields. A major part of Bovern's research from his PhD thesis centres around understanding the interaction between animal hosts and their associated microbial community under extremely high thermal environments, which holds significant implications to unravel the mechanisms that govern their tolerance range and limit under warming oceans in the future. The awarded grant was applied with the support of his PhD supervisor, Professor Juan Diego GAITÁN-ESPITIA, that aims as a follow-up work from this PhD thesis, to delve deeper into the working mechanisms underpinning organismal survival and tolerance under extreme conditions. Currently, Bovern is a Postdoctoral fellow being supervised by Professor Bayden RUSSELL at the School of Biological Sciences.

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Joint Study by HKU and HKUST on DNA Replication Initiation Selected as One of Top 10 Scientific Advances in China for 2023

A joint study revealing a new mechanism on DNA Replication Initiation, led by The Hong Kong University of Science and Technology (HKUST), The University of Hong Kong (HKU) and other institutions, has been selected as one of the Top 10 Scientific Advances in China for 2023, making it the only research project from Hong Kong to be included in the list. Organised by the National Natural Science Foundation of China, the "Top 10 Scientific Advances in China for 2023" is jointly hosted by the High Technology Research and Development Center and the Center for Science Communication and Achievement Transformation, with the support of five journals, namely China Basic Science, Science & Technology Review, Bulletin of the Chinese Academy of Sciences, Science Foundation in China, and Science Bulletin. These 10 advancements were judiciously selected by thousands of experts from the Chinese Academy of Sciences, Chinese Academy of Engineering, and other institutions. The objective is to promote frontier and innovative research progress in China and encourage more researchers to engage in basic research. By deepening public understanding, concern and support for science, the event also seeks to foster a national climate favourable to scientific exploration. This prestigious accolade was awarded to the team that includes Prof. ZHAI Yuanliang, Assistant Professor from the HKU School of Biological Sciences, Prof. DANG Shangyu, Assistant Professor from HKUST Division of Life Science (LIFS), and Prof. TYE Bik-Kwoon, Senior Member of HKUST Institute for Advanced Study (IAS), in recognition of their groundbreaking discovery of a new mechanism of the human pre-replication complex (Pre-RC) in regulating DNA replication initiation. The atomic resolution structure of the human Pre-RC provides detailed critical information for devising novel and effective anticancer strategies with the ability to selectively kill cancer cells. “This recognition is a great honour for our research team and shows that our work is highly respected in the scientific community,” said Prof. Zhai Yuanliang from HKU. “Our knowledge of how DNA is copied is still quite limited. While previous studies in a type of yeast have given us some insights, there's still so much we don't know about how this process happens in human cells. Since there's still a lot to discover in this field, every new development in understanding how DNA is copied by our replication machines is a big step forward. The knowledge we gain from our research will not only deepen our understanding of the basic processes of life, but it may also provide important insights into diseases like cancer and help us find new ways to treat them.” Prof. Dang Shangyu from HKUST said, "Enhancing the specificity of chemotherapy drugs has always been a crucial consideration in developing anticancer compounds. We are delighted that our research breakthrough has received national recognition. Notably, all of the project’s structural work, including cryo-sample preparation, cryo-EM data collection and processing, was conducted at the HKUST Biological Cryo-EM Center. We are immensely grateful to the Lo Kwee Seong (LKS) Foundation for their generous support in establishing this state-of-the-art facility at HKUST, which has already facilitated several breakthroughs and discoveries in our research since its establishment in 2019. We look forward to continuing our investigations in this field and forging new hopes for cancer treatment." Research Background DNA is the blueprint of life. It is present in every cell. Its duplex structure in complementary notations informs how it is replicated. It must be first separated into single strands and copied precisely. The history of DNA replication study can be traced back to 1950s when Prof. Arthur KORNBERG discovered an enzyme system in Escherichia coli extracts, which ultimately earned him a Nobel Prize. However, due to the lack of high-resolution structures, progress in DNA replication research lagged behind those achieved in the study of other macro molecular machines, such as the ribosome or the RNA polymerase. Professor Tye Bik-Kwoon, who has joined HKUST since 2011, overcome these hurdles initially by collaborating with the Peking University team led by Professor GAO Ning, as well as Prof. Zhai, who obtained his PhD from HKUST before becoming a HKUST-IAS junior fellow. Together they made a series of groundbreaking findings, including determining the cryo electron microscopy (cryo-EM) structures of the yeast MCM2-7 double hexamer (DH) and the yeast origin recognition complex, which were published in Nature in 2015 and 2018. These studies laid the foundation for the present work on the structure of the human pre-replication complex when the HKUST cryo-EM facility became available and when Prof. Dang joined HKUST in 2019. As one of the Top 10 Scientific Advances in China for 2023, this research determined at 2.59 Å the cryo-EM structure of the human Pre-RC, which is formed by the loading of the MCM2-7 DH onto origin DNA. This structure provides a clear understanding of how the MCM2-7 complex destabilises DNA, leading to the initial unwinding of the DNA duplex precisely at the juncture of the two coupled MCM2-7 hexamers. Additionally, the team discovered that the MCM2-7 DH complexes are loaded onto DNA at numerous sites throughout the human genome. Importantly, these sites are mutually exclusive with loci of active transcription to minimise interference between DNA replication and transcription. Moreover, when the initial open structure is disrupted, the MCM2-7 DH complexes fail to assemble onto DNA, resulting in a complete suppression of DNA replication initiation. The study provides a detailed understanding of the high-resolution structure and mechanism of the human Pre-RC. This knowledge can be leveraged to develop non-toxic anticancer drugs in the future. The research was published in the top international scientific journal Cell in January, 2023. (click here for link) About The University of Hong Kong Founded in 1911, The University of Hong Kong (HKU)( www.hku.hk) is the first and oldest institution of higher education in Hong Kong. For over a century, the University has dedicated itself to creating knowledge, providing education, and serving society. Today, HKU has an established worldwide reputation for being a research-led comprehensive University with ten Faculties. HKU has a proud record of academic recognition in research through honours and awards received from both local and international bodies. The University strives to attract and nurture outstanding scholars through excellence and innovation in its research and knowledge exchange activities. Its research areas cover a wide range of issues with the aim of benefitting industries, businesses and the community. Regarded as Asia’s Global University, HKU brings together experts from diverse disciplines, partnering with prestigious universities and research institutes around the world. It has 51 academics named on the list of “Highly Cited Researchers 2023” from Clarivate, ranking 13th globally among all institutions. HKU is in pursuit of teaching and learning excellence in a broad range of disciplines and professions. With the holistic design of the curricula, along with award-winning teaching and learning resources and support, students at HKU can fully develop intellectual and personal strengths while gaining lifelong learning opportunities to contribute to the community. About The Hong Kong University of Science and Technology The Hong Kong University of Science and Technology (HKUST) (https://hkust.edu.hk/) is a world-class research intensive university that focuses on science, engineering and business as well as humanities and social science. HKUST offers an international campus, and a holistic and interdisciplinary pedagogy to nurture well-rounded graduates with global vision, a strong entrepreneurial spirit and innovative thinking. Over 80% of our research work were rated “Internationally excellent” or “world leading” in the Research Assessment Exercise 2020 of Hong Kong’s University Grants Committee. We were ranked 2nd in Times Higher Education’s Young University Rankings 2023, and our graduates were ranked 29th worldwide and among the best from universities from Asia in Global Employability University Ranking 2023. As of September 2023, HKUST members have founded 1,747 active start-ups, including 9 Unicorns and 13 exits (IPO or M&A), generating economic impact worth over HK$ 400 billion. InvestHK cited QS World University Rankings by Subject 2021 to demonstrate the performance of five world’s top 100 local universities in several innovation-centric areas, among which HKUST ranked top in four engineering and materials science subjects.    

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HKU Chemists Pave the Way for Sustainable Organic Synthesis with Innovative Heterogeneous Copper Photocatalysis, Enabling Efficient Production of Diverse Bioactive Compounds

Professor Jian HE, from the Department of Chemistry at The University of Hong Kong (HKU), has spearheaded a research endeavour aimed at revolutionising organic synthesis. His research team has successfully developed a novel heterogeneous copper photocatalyst that enables the efficient formation of cyclobutane rings, a crucial structural element in a vast array of bioactive molecules. Cyclobutane rings are prominently featured in pharmaceuticals, natural products, and various biologically active compounds. By enabling researchers to construct these rings easily and selectively, Professor He's team has unlocked greater control over the synthesis of these vital molecules. The research findings are recently published online in the top scientific journal Nature Catalysis. In recent two decades, visible-light photocatalysts have been employed to drive such transformations through photochemical [2+2] cycloadditions; however, their substrate scope has been limited. Moreover, existing photocatalytic systems often rely on homogeneous precious metal catalysts, which pose challenges in catalyst recycling and hinder large-scale organic synthesis. Addressing these limitations head-on, Professor He and his team have developed an innovative heterogeneous copper photocatalyst. This catalyst effectively facilitates energy-transfer processes for a range of intermolecular crossed [2+2] cycloadditions, including those previously inaccessible in conventional homogeneous photocatalysis. This new reaction system has excellent catalyst stability and recyclability, and it does not rely on precious metals, making it more economically and environmentally sustainable. Professor He expressed great enthusiasm for the potential impact of this discovery, stating, ‘Our novel heterogeneous copper photocatalyst opens up new possibilities for synthesising bioactive molecules with enhanced efficiency and selectivity. By eliminating the reliance on precious metals and improving catalyst recyclability, we have addressed critical challenges in large-scale organic synthesis, paving the way for more sustainable and economically viable chemical production.’ Key findings In this study, the team developed a special kind of copper photocatalyst that can help make cyclobutane molecules more efficiently. They successfully prepared a stable heterogeneous copper triplet photosensitiser by constructing binap-ligated heteroleptic copper(I) complexes in the pores of zirconium-based metal–organic frameworks (MOFs). Upon heterogenisation, reactive copper(I) species in photoexcited states show increased transition energies and lifetime, which is essential for boosting catalytic efficiency in energy-transfer-mediated [2+2] cycloadditions of styrenes with a variety of olefins, including electron-deficient alkenes. Unlike the corresponding homogeneous copper photocatalysts, the MOF-supported copper photocatalyst exhibits high stability and catalytic activity, and can be recycled multiple runs without catalyst decomposition. This work provides a general and interdisciplinary approach to designing highly reactive copper photocatalysts for a wide range of practical organic reactions, and it could help make the process of producing diverse bioactive compounds easier and more efficient in the future. About Professor Jian He Professor Jian He is an Assistant Professor in the Department of Chemistry and State Key Laboratory of Synthetic Chemistry at The University of Hong Kong. His independent research programme, at the interface between organic chemistry, inorganic chemistry, and materials science, is rooted in the design of novel framework- and cluster-based catalysts for the advancement of sustainable organic synthesis. He has received multiple awards, including The Alfred R. Bader Award for Student Innovation in 2014, International Precious Metals Institute Student Award in 2015, Reaxys PhD Prize Finalist in 2015, ACS Division of Organic Chemistry Travel Award in 2015, Chinese Government Award for Outstanding Self-Financed Students Abroad in 2015, IUPAC-Solvay Honorable Mention Prize in 2017, and Croucher Innovation Award in 2021. About the Research Team Dr Jun GUO and Mr Qi XIA from Professor HE’s group are the co-first authors. Other researchers, including Wing Yi TANG, Zekun LI, Xia WU, Li-Juan LIU, Wai-Pong TO, Hui-Xing SHU, Kam-Hung LOW, and Professor Philip C. Y. CHOW from HKU and Professor Tsz Woon Benedict LO from The Hong Kong Polytechnic University, contribute to this project. Journal title: ‘Visible light-mediated intermolecular crossed [2+2] cycloadditions using a MOF-supported copper triplet photosensitizer’ (Nature Catalysis, 2024).  

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2023 Chinese Chemical Society Young Chemist Award

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Diverse Ancient Volcanoes on Mars Discovered by HKU Planetary Scientist May Hold Clues to Pre-plate Tectonic Activity on Earth

Volcanoes are a common feature on the surfaces of solid planets within the solar system, resulting from magmatic activity occurring within the planetary crust. On Earth, volcanism is driven primarily by heat and crustal recycling associated with plate tectonics, but Mars lacks plate tectonics and the driver of volcanism is not well understood. Recent research by Professor Joseph MICHALSKI, a geologist in the Department of Earth Sciences at The University of Hong Kong (HKU), has revealed intriguing insights into the volcanic activity on Mars. He proposes that Mars has significantly more diverse volcanism than previously realised, driven by an early form of crust recycling called vertical tectonics. The findings, recently published in Nature Astronomy, shed light on the ancient crust of Mars and its potential implications for understanding early crustal recycling on both Mars and Earth. Traditionally, Mars has been known to have large shield volcanoes similar to those in Hawaii. However, it was not known that Mars also possessed the diverse, explosive volcanoes that form on Earth due to crustal recycling. The recent research conducted by Professor Michalski and his international team discover a vast number of diverse volcanoes in the ancient crust of Mars. ‘We have known for decades that Mars has volcanoes, but most of the recognised volcanoes correspond to large basaltic shield volcanoes similar to the ones that make up Hawaii,’ he explains. ‘In this work, we show that the ancient crust has many other types of volcanoes such as lava domes, stratovolcanoes, calderas and large shields of ash, not lava. Further, most scientists see Mars as a planet composed of basalt, which has low silica content and represents little crustal evolution, but these volcanoes have high silica content which means they formed from a complex process of magma evolution not known before.’ Colour image data are draped onto topography to show a 3-D view of a large stratovolcano in the Eridania region of Mars. Image Credit: NASA/ESA/HRSC. The paper suggests that intense volcanism occurred on ancient Mars, causing the crust to collapse into the mantle, where the rocks re-melted, resulting in magmas that have high silica. This tectonic process, called vertical tectonics, is hypothesised to have occurred on the ancient Earth, but rocks on Earth from that period (the Archean, more than 3 billion years ago) are highly modified by later geological activity, so we cannot see evidence for this process clearly on this planet. Therefore, exploring other planets like Mars, which has volcanism but no plate tectonics, can help reveal the mysteries of early crustal recycling on both the Red Planet, and by analogy, on early Earth. Professor Michalski concluded, ‘Mars contains critical geological puzzle pieces that help us understand not only that planet, but the Earth as well. Martian volcanism is much more complex and diverse than has been previously thought.’ ‘This is a significant discovery because it has revealed that crustal recycling can occur not only in plate tectonic regimes dominated by horizontal movements, but can also occur in pre-plate tectonic regimes dominated by vertical movements. This finding can help earth scientists revolve the long-term controversial issues of how and when felsic continents formed in our planet (Earth)’, said Professor Guochun ZHAO, the Chair Professor of HKU Earth Sciences.   The journal paper can be accessed here.    About Professor Joseph Michalski A Professor in the Department of Earth Sciences and Deputy Director of the Laboratory for Space Research at HKU, he collaborated with colleagues from mainland China and USA on this research project. He is a Research Fellow of the Hong Kong Research Grants Council, and winner of a Tencent Xplorer Prize in 2023. The funding for this work was provided by the RGC Collaborative Research Fund. For more information on Professor Joseph Michalski's research, please visit here.  Twitter: @JoePlanets 

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The Art of Sparkling Tea: A Fusion of Science and Craftsmanship

Lifestyle embodies an attitude, and the philosophy behind business operations is truly invaluable. When we merge these principles and infuse mindfulness into our everyday existence, we ignite genuine sparks in our lives. In an enlightening conversation with Winston LAU, the visionary behind Mindful Sparks, we delved into the origins of his venture. As a Food and Nutritional Science graduate from HKU, Winston's love for wine sparked a desire to develop an exquisite beverage to those who sought an alcohol-free yet sophisticated option. ‘What we’re trying to do is to maximise the flavour experience that people can enjoy, the aroma, the taste, and the aftertaste during fine-dining food pairings,’ said Winston. A Journey Fueled by Passion and Purpose ‘By utilising a multidimensional extraction technique and focusing on the full potential of Chinese tea, we aim to elevate the tea-drinking experience to a fine-dining level,’ Winston revealed the meticulous craftsmanship behind Mindful Sparks' sparkling tea. Through a unique extraction method named 'Layer Six Extraction', developed in collaboration with Professor Jetty LEE of the School of Biological Sciences, the team extracts the polyphenols - the nutrients and complex flavours - from tea leaves. This process, combined with a three-day maturation and delicate carbonation, results in a champagne-like sparkling tea that exudes sophistication. As a graduate in food science, Winston consistently prioritises upholding a strong food safety management system. ‘Despite our relatively short two-year establishment, we’ve successfully secured ISO 22,000, HACCP and HALAL certifications – a noteworthy accomplishment for a company of our size,’ remarked Winston. He highlights that these certifications are pivotal in advancing the company’s food safety management and production processes, facilitating collaborations with leading top hotel chains and retailers.   BSc Alumus (majored in Food and Nutritional Science) Winston Lau, Founder and CEO of Mindful Sparks Elevate and innovate tea traditions to create a healthy luxury lifestyle, a new culture to the world! Winston collaborated with the team led by Professor Jetty LEE (second person from the right in the first row) from HKU School of Biological Sciences to develope the Layer 6 Extraction method to craft his sparkling teas.  The Intersection of Science, Sustainability, and Innovation Drawing from his scientific background, Winston shared how his Food and Nutritional Science education contributed to his business operations. ‘My scientific training at HKU equipped me with critical thinking skills and a problem-solving mindset that are invaluable in the business world,’ explained Winston. The knowledge gained in food chemistry, marketing, and sensory evaluation courses empowered him to develop innovative solutions, such as the upcycling of cacao waste into the Blood Orange Cacao Husk Sparkling Tea. Winston emphasised the importance of aligning one's academic pursuits with personal interests and career goals. ‘My four years of studying food and nutritional science not only broadened my knowledge but also provided a solid foundation for my entrepreneurial journey,’ highlighted Winston. Dedicated to complexity, flavour, and sustainability, Winston has skillfully established a presence in the non-alcoholic beverage market, presenting a luxurious and health-conscious alternative. His journey is a source of inspiration for individuals aspiring to blend their passions with academic pursuits, paving the way for a fulfilling and impactful career. Mindful Sparks' sparkling tea leaves us with an elevated appreciation for the artistry and innovation encapsulated in every sip. Click here to learn more about Mindful Sparks. 

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HKU Astrophysicists Crack the Case of the “Disappearing” Sulphur in Planetary Nebulae

Two astrophysicists from the Laboratory for Space Research (LSR) at The University of Hong Kong (HKU) have finally solved a 20-year-old astrophysical puzzle concerning the lower-than-expected amounts of the element Sulphur found in Planetary Nebulae (PNe) in comparison to expectations and measurements of other elements and other types of astrophysical objects. The expected levels of Sulphur have long appeared to be “missing in action”. However, they have now finally reported for duty after hiding in plain sight, as a result of leveraging highly accurate and reliable data. The team has recently reported their findings in Astrophysical Journal Letters. Background PNe are the short-lived glowing, ejected, gaseous shrouds of dying stars that have long fascinated and enthused professional and amateur astronomers alike with their colourful and varied shapes. PNe live for only a few tens of thousands of years compared to their host stars, which can take billions of years before they pass through the PN phase on the way to becoming “white dwarfs”. Consequently, PNe provide an almost instantaneous snapshot of stellar death throes. They are a vital, scientific window into late-stage stellar evolution as their rich emission line spectra enable detailed studies of their chemical compositions. The Enigmatic Sulphur Anomaly Past studies showed that PNe optical spectra appeared to have a varying deficit of the element Sulphur. This deficit was difficult to explain because Sulphur, known as an “α element”, should be produced in lockstep with other elements like oxygen, neon, argon and chlorine in more massive stars. As a result, its cosmic abundance should also be directly proportional. Surprisingly, while strong correlations between Sulphur and Oxygen abundances have been observed in H II regions (Hydrogen ionised region) and blue compact galaxies (see figure 2), PNe originating from low- to intermediate-mass stars consistently exhibit lower Sulfur levels, giving rise to the so-called mysterious “sulfur anomaly” that has perplexed and annoyed astronomers for decades. Our Work Solving the Mystery Ms Shuyu TAN, a graduate of HKU MPhil in Physics and Research Assistant at HKU LSR, along with her supervisor Professor Quentin PARKER, the Director of LSR, utilised an unprecedented sample of exceptional high signal to noise (S/N) optical spectra for approximately 130 PNe located in the centre of our Galaxy. This exceptional dataset had minimal background noise, allowing for a clear and detailed examination of the spectral features, helping the team effectively tackle and solve the mystery. These PNe were observed using the world-leading European Southern Observatory (ESO) 8m Very Large Telescope in Chile. It turns out the anomaly was essentially a result of poor data quality for Sulphur emission lines in PNe spectra. It was found that using Oxygen as the base metallicity comparator to other elements was not accurate, and instead, Argon demonstrated a stronger correlation with Oxygen for Sulphur and has been suggested as a more reliable indicator of metallicity and a suitable comparison element. So, when a large, carefully selected sample of PNe are spectroscopically observed at high S/N on a large telescope, not only did the data reveal a strong “lock-step” behaviour or Sulphur in PNe for the first time, as seen and expected for other types of astrophysical objects, but the anomaly itself effectively went away.   This is shown in the two key plots from the paper below: Figure 2. The vertical axis for both plots – sulphur abundance relative to Hydrogen. Left plot – the sulphur anomaly (blue points are for PNe, green points for HII regions and blue compact galaxies) where Sulfur is shown relative to Oxygen. There is a large scatter for PN measure compared to the 1:1 lock-step behaviour expected and seen for other alpha elements in PNe. Right plot: The green points are as before but this time the orange points are for the PNe from our VLT galactic centre PN sample and with sulphur plotted against Argon rather than Oxygen. There is now lock-step behaviour seen for sulphur for the first time and a parallel track and much tighter relationship where the anomaly is almost extinguished. Image credit: Figure adapted from The Astrophysical Journal Letters, 961:L47(9pp),2024 February 1. The authors have effectively disproven previous claims suggesting that the sulfur anomaly in Planetary Nebulae was a result of underestimated higher sulfur ionization stages or weak sulfur line fluxes. This finding underscores the critical importance of high-quality data in unraveling scientific mysteries. The Journal paper can be accessed here: https://iopscience.iop.org/article/10.3847/2041-8213/ad1ed9/pdf   Figure 3. Image from an ESO telescope in Chile of Planetary Nebulae PN NGC 5189. Some say it looks like a Chinese flying Dragon in space. Image credits: ESO          

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Recovering Lossless Propagation: HKU Physicists Overcoming Optical Loss in Polariton System with Synthetic Complex Frequency Waves

A collaborative research team co-led by Professor Shuang ZHANG, the Interim Head of the Department of Physics, The University of Hong Kong (HKU), along with Professor Qing DAI from National Center for Nanoscience and Technology, China, has introduced a solution to a prevalent issue in the realm of nanophotonics – the study of light at an extremely small scale. Their findings, recently published in the prestigious academic journal Nature Materials, propose a synthetic complex frequency wave (CFW) approach to address optical loss in polariton propagation. These findings offer practical solutions such as more efficient light-based devices for faster and more compact data storage and processing in devices such as computer chips and data storage devices, and improved accuracy in sensors, imaging techniques, and security systems. Surface plasmon polaritons and phonon polaritons offer advantages such as efficient energy storage, local field enhancement, and high sensitivities, benefitting from their ability to confine light at small scales. However, their practical applications are hindered by the issue of ohmic loss, which causes energy dissipation when interacting with natural materials. Over the past three decades, this limitation has impeded progress in nanophotonics for sensing, superimaging, and nanophotonic circuits. Overcoming ohmic loss would significantly enhance device performance, enabling advancement in sensing technology, high-resolution imaging, and advanced nanophotonic circuits. Professor Shuang Zhang, corresponding author of the paper, explained the research focus, ‘To address the optical loss challenge in key applications, we have put forward a practical solution. By employing a novel synthetic complex wave excitation, we can achieve virtual gain and counteract the intrinsic loss of the polariton system. To validate this approach, we applied it to the phonon polariton propagation system and observed a significant improvement in polariton propagation.’ ‘We demonstrated our approach by conducting experiments using phonon polariton material, such as hBN and MoO3, in the optical frequency range. As expected, we obtained nearly lossless propagation distance consistent with our theoretical predictions,’ added Dr Fuxin GUAN, the paper’s first author and a Postdoctoral Fellow at the Department of Physics at HKU.   Multi-frequency approach to overcome optical loss In this research, the team developed a novel multiple-frequency approach to address energy loss in polariton propagation. They used a special type of wave called ‘complex frequency waves’ to achieve virtual gain and compensate for the loss in an optical system. While a regular wave maintains a constant amplitude or intensity over time, a complex frequency wave exhibits both oscillation and amplification simultaneously. This characteristic allows for a more comprehensive representation of wave behaviour and enables compensation for energy loss. While frequency is commonly perceived as a real number, it can also have an imaginary part. This imaginary part tells us how the wave either gets stronger or weaker over time. Waves with a complex frequency featuring a negative (positive) imaginary part decay (amplify) over time. However, directly carrying our measurement under the excitation of complex frequency waves in optics is challenging because it requires complex time-gated measurements. To overcome this, the researchers employed the Fourier Transformation mathematical tool to break down a truncated complex frequency wave (CFW) into multiple components with individual frequencies. Just like when you are cooking and need a specific ingredient that is hard to find, the researchers used a similar idea. They broke down the complex frequency waves into simpler components, like using substitute ingredients in a recipe. Each component represented a different aspect of the wave. It is like creating a delicious dish by using substitute ingredients to get the desired flavour. By measuring these components at different frequencies and combining the data, they reconstructed the behaviour of the system illuminated by the complex frequency wave. This helped them understand and compensate for the energy loss. This approach greatly simplifies the practical implementation of CFWs in different applications, including polariton propagation and superimaging. By conducting optical measurements at different real frequencies with a fixed interval, it becomes feasible to construct the optical response of the system at a complex frequency. This is achieved by mathematically combining the optical responses obtained at different real frequencies. Professor Qing DAI, the National Center for Nanoscience and Technology and another corresponding author of the paper, stated that this work has provided a practical solution to address the long-standing issue of optical loss in nanophotonics. He highlighted the significance of the synthesised complex-frequency method, stating that it can be easily applied to various other applications like molecular sensing and nanophotonic integrated circuits. He further emphasised that ‘this method is remarkable and universally applicable, as it can also be utilised to address loss in other wave systems, including sound waves, elastic waves, and quantum waves, thereby enhancing the quality of imaging to unprecedented levels.’ This work was supported by the New Cornerstone Science Foundation, the Research Grants Council of Hong Kong. The journal paper ‘Compensating losses in polariton propagation with synthesized complex frequency excitation’ can be accessed here. Click here to learn more about Professor Shuang Zhang.    Supplementary Note: Experimental Demonstration As a proof of concept, the team started with phonon polaritons (PhPs) propagation at optical frequencies about 1450 cm-1 using hBN films. A long gold antenna placed on the hBN film is used to launch the 1D PhPs. The field distributions of the two real frequencies and the two complex frequencies are displayed in Fig. 2a and 2b, respectively. The experimental results demonstrate that while the propagation at the real frequencies suffers strong attenuation, the polariton at the complex frequencies experiences almost no decay along the propagation. Figure 2. 1D Polariton propagation (from left to right) using hBN film operating at optical frequency. (a) Real frequency images show obvious decay field profile at propagation direction. (b) Complex frequency measurements provide almost non-dissipative propagation behavior. Figures adapted from Nature Materials, 2024, doi.org/10.1038/s41563-023-01787-8. The team further applied the complex frequency approach to investigate the more complicated field distributions supported by a thin film of van der Waals crystal α-MoO3, which is highly anisotropic and supports natural in-plane hyperbolic polaritons. A metal antenna as an excitation source is placed on the α-MoO3 film as shown in Fig. 3a. The field distribution variation exhibits a characteristic hyperbolic propagation behaviour with a concave wavefront see Fig. 3b. With the increase of the frequency, the wavelength decreases with a stronger field confinement, and meanwhile, the propagation becomes more attenuated. All of these real frequency plots are combined according to the ratio of complex frequency to obtain the complex frequency result in Fig. 3c. The team finally investigated the interference behavior of PhPs using the complex frequency approach. Two circular antennas with different diameters are fabricated on the MoO3 film to excite the phonon polaritons, as shown in Fig. 3d. While the real frequency plots cannot show clear interference fringes, as shown in Fig. 3e, the complex frequency plots of clear interference fringes can be synthesised after combining the results of different real frequencies and as shown in Fig. 3f.   Figure 3. Hyperbolic phonon polariton and elliptical phonon polariton propagation on α-MoO3 film. (a) AFM of an antenna placed on the α-MoO3 film. (b) Real frequency measurements of hyperbolic polariton in different real frequencies. (c) Complex frequency measurement provides an ultra-long distance propagation behavior. (d) AFM of two different spaced gold antennas. (e) The amplitude and real part of the measurements at real frequency f=990cm-1. (f) The amplitude and real part of measurements at complex frequency f=(990-2i)cm-1. Figures adapted from Nature Materials, 2024, doi.org/10.1038/s41563-023-01787-8.

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Science Teachers Recognised with HKU Excellence Awards 2023

Congratulations to our academics for receiving the University's innovator, research and teaching excellence awards in the HKU Excellence Award Scheme 2023. The list of award recipients is appended as follows:    HKU Innovator Award Professor Hongzhe SUN  Norman & Cecilia Yip Professor in Bioinorganic Chemistry and Chair Professor of Chemistry   Outstanding Researcher Awards Outstanding Researcher Award  Professor Xiang David LI  Professor, Department of Chemistry   Outstanding Young Researcher Award Professor Junzhi LIU  Assistant Professor, Department of Chemistry   Research Output Prize Professor Aleksandra DJURIŠIĆ Professor, Department of Physics Details of the awarded journal paper: 'Monolithic perovskite/organic tandem solar cells with 23.6% efficiency enabled by reduced voltage losses and optimized interconnecting layer', Nature Energy 2022, 7(3), 229–237 by Chen, Wei, Zhu, Yudong, Xiu, Jingwei, Chen, Guocong, Liang, Haoming, Liu, Shunchang, Xue, Hansong, Birgersson, Erik, Ho, Jian Wei, Qin, Xinshun, Lin, Jingyang, Ma, Ruijie, Liu, Tao, He, Yanling, Ng, Alan M.C., Guo, Xugang, He, Zhubing, Yan, He, Djurišić, Aleksandra B.*, & Hou, Yi.   Teaching Excellence Award   Early Career Teaching Award Professor Ying Wai CHAN  Assistant Professor, School of Biological Sciences     Congratulations to all the recipients on their well-deserved achievements!     The university-level HKU Innovator Award recognises outstanding Faculty members whose innovations demonstrate exceptionally high potential impact (legacy or projected legacy) with transformative results to foster development.    The Outstanding Researcher Awards scheme aims to recognise, honour and reward exceptional work in research by staff of the University. The scheme includes the Distinguished Research Achievement Award (DRAA), Outstanding Researcher Award (ORA), Outstanding Young Researcher Award (OYRA), Outstanding Research Student Supervisor Award (ORSSA), and Research Output Prize (ROP). The DRAA, ORA and OYRA are awards made to recognise individuals for their outstanding research accomplishments. The ORSSA is to recognise exemplary and effective supervisory guidance and support to their research postgraduate students. The ROP is a Faculty-based award to honour the best research output from each Faculty.   The Teaching Excellence Award Scheme aims to recognise, reward and promote excellence in teaching at the University. Under the Scheme, there are four categories of awards, viz. University Distinguished Teaching Award, Outstanding Teaching Award (OTA), Early Career Teaching Award (ECTA) and Teaching Innovation Award (TIA). Besides individual awards, both OTA and TIA comprise team awards to recognise and encourage collaborative effort and achievement in enhancing teaching and learning. Faculties should encourage their teachers with outstanding contributions to teaching and learning to apply for these awards.

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Faculty of Science secures funding for high-quality cross-disciplinary research projects in 2023/24 Collaborative Research Fund (CRF)

In the recent announcement of the Research Grants Council (RGC) 2023/24 funding exercise, the Faculty of Science has achieved funding for two projects under the Collaborative Research Fund (CRF), with a total funding of HK$12.2 million. This year, the awarded projects include one Collaborative Research Project Grant (CRPG) and one Young Collaborative Research Grant (YCRG).   Established by the University Grants Committee (UGC), the CRF encourages and supports multi-investigator collaboration in diverse disciplines to engage in creative and high-quality cross-disciplinary projects.    The Collaborative Research Project Grant and the Young Collaborative Research Grant (YCRG) aim to enhance university research output and support early-stage academic staff. By encouraging research groups in UGC-funded universities to engage in interdisciplinary collaboration, these grants foster both project development and the career progression of researchers.   The following projects have been awarded: Department/ School Project Title Project Coordinator RGC  Fund Approved Project Period Collaborative Research Project Grant (CRPG) Biological Sciences Integrative structural and chemical biology approaches to investigate pre-replicative complex assembly and its applications in human diseases 整合結構和化學生物學方法研究人體細胞複製前始複合物的組裝及其在疾病治療中的應用 Professor Yuanliang ZHAI HK$8,190,772  3 Years Young Collaborative Research Grant (YCRG) Chemistry   Accessing Molecular Complexity and Functionality from Active Methylene Compounds via Asymmetric Catalysis 通過亞甲基化合物的不對稱轉化構建複雜和功能分子 Professor Zhongxing HUANG HK$4,024,624  3 Years    For more details about the funding results, please click here.  

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Three Research Projects from Faculty of Science Secured Funding under the NSFC/RGC Joint and Collaborative Research Schemes

Nine research projects from The University of Hong Kong (HKU) have successfully secured funding under the National Natural Science Foundation for China and the Research Grants Council (NSFC/RGC) 2023/24 Exercise. Notably, three of these projects are from the Faculty of Science. Two of the successful projects were selected for funding under the NSFC/RGC Joint Research Scheme (JRS), with Professor Lixin DAI from the Department of Physics and Professor Xiaoyu LI from the Department of Chemistry leading as Principal Investigators. Additionally, another project secured funding through the NSFC/RGC Collaborative Research Scheme (CRS), spearheaded by Professor Yuanliang ZHAI from the School of Biological Sciences. The Research Grants Council of Hong Kong (RGC) earlier announced the funding results. The JRS aims to foster collaboration between researchers and research teams in Hong Kong and the mainland, leveraging the unique strengths of both regions. On the other hand, the CRS focuses on promoting larger-scale, interdisciplinary collaborative research involving universities across mainland China and Hong Kong, with the goal of enhancing research output and impact for both areas.   Details of the funded projects from Faculty of Science are as follows: HKU Science project funded under NSFC/RGC Collaborative Research Scheme: Mechanistic Study of the Parental Histone Recycling at Replication Forks Project Coordinator (Hong Kong): Professor Yuanliang Zhai, School of Biological Sciences   HKU Science projects funded under NSFC/RGC Joint Research Scheme: Investigating the Properties and Impacts of the Wind Launched from Black Hole Super-Eddington Accretion Flow Principal Investigator (Hong Kong): Professor Lixin Dai, Department of Physics Discovery of Novel Molecular Glue Molecules by Using DNA-encoded Chemical Libraries (DELs) Principal Investigator (Hong Kong): Professor Xiaoyu Li, Department of Chemistry

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HKU Students Shine Again with Gold Medal in International iGEM Competition 2023

A team of HKU students from the Faculty of Science, LKS Faculty of Medicine, and Faculty of Engineering have demonstrated their dedication and skill by earning a gold medal in the International Genetically Engineered Machine (iGEM) Competition Grand Jamboree 2023. The competition invites teams to develop projects using synthetic biology to address current global challenges.   This year's HKU iGEM team focused on a project aimed at improving the treatment of solid tumours by genetically engineering macrophages with chimeric antigen receptor (CAR) combined with SIRPα blocker. This approach seeks to enhance the effectiveness of macrophages in the tumour microenvironment (TME) and potentially pave the way for an ‘off-the-shelf’ immunotherapy method.   The gold medal serves as a testament to the team's hard work and commitment to the project. Their efforts in wet lab work, science communication, and education contributed to their success in the competition.   Team Leaders: School of Biological Sciences, Faculty of Science: Cyrus King Chung WONG and CHEUNG Chi Hung Jim School of Nursing, LKS Faculty of Medicine: SZE Tsz Yan   Team members: School of Biological Sciences, Faculty of Science: Cheng YIN, SO Man Lok, Lehan HU, Polly ZHOU, GENG Yi Rong, CHIU San Bo, Xin Yue LIM School of Biomedical Sciences, LKS Faculty of Medicine: Hoi Ching Gisela TSOI, Chong Wing LAM, Wing Hei LAM Department of Biomedical Engineering, Faculty of Engineering: Aijing LIN, Siddhant NINGOO   Team supervisors: Prof SUGIMURA Rio Ryohichi from LSK Faculty of Medicine Prof Kevin K.M. Tsia from the Faculty of Engineering   Instructors: Mr Ng Tsz Chun, a PhD student from the Faculty of Science Vicera Christian Nelson Tejedor, an alumnus 

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Physics PhD Student Honoured with Research Postgraduate Student Innovation Award (2023/24) for Insights into Dark Matter Research

Congratulations to Mr Alfred Amruth, a PhD student at the Department of Physics, on receiving the Research Postgraduate Student Innovation Award 2023/24. Amruth's research focuses on dark matter and gravitational lensing. His innovative approach to solving the mystery of dark matter in the universe has attracted widespread attention in academia. His research paper ‘Einstein rings modulated by wavelike dark matter from anomalies in gravitationally lensed image’ was selected as the cover article for Nature Astronomy, a renowned scientific journal in the field. Dark matter constitutes the majority of mass in our Universe, yet its true nature remains a mystery. Understanding what dark matter is stands as one of the most fundamental questions in physics. Amruth believes that dark matter could potentially be the next ‘fuel’ for elevating human civilisation and possibly help us become true space explorers. Currently, Amruth is working actively with collaborators worldwide to study the effects of wave-like dark matter in galaxies. He attributes his development as a scientist to the invaluable mentorship of his supervisor, Dr Jeremy LIM, as well as the unwavering support of his collaborators and colleagues. Established in 2022 by the HKU Graduate School and the Technology Transfer Office, the Research Postgraduate Student Innovation Award recognises up to ten research postgraduate students each year for their most exciting and innovative research ideas. Additionally, Amruth has been awarded the 2023 Hong Kong Young Scientist Award in Physical/Mathematical Science by the Hong Kong Institution of Science. This award recognises the young scientists and engineers in Hong Kong who demonstrate exceptional potential in their respective fields of study. It aims to foster the development of science and technology in the region.

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