City University of Hong Kong
Recent publications
Exposure to triclosan (TCS) has been reported to reduce photosynthetic pigments, suppress photosynthesis, and inhibit growth in both prokaryotic and eukaryotic algae including Anabaena flos-aquae (a model cyanobacterium). In particular, cyanobacteria are more sensitive to TCS toxicity compared to eukaryotic algae possibly due to the structural similarity to bacteria (target organisms); however, whether TCS exerts its toxicity to cyanobacteria by targeting signaling pathways of fatty acid biosynthesis as in bacteria remains virtually unknown, particularly at environmental exposure levels. With the complete genome sequence of A. flos-aquae presented in this study, the transcriptomic alterations and potential toxic mechanisms in A. flos-aquae under TCS stress were revealed. The growth, photosynthetic pigments and activity of A. flos-aquae were markedly suppressed following a 7-day TCS exposure at 0.5 µg/L but not 0.1 µg/L (both concentrations applied are environmentally relevant). The transcriptomic sequencing analysis showed that signaling pathways, such as biofilm formation – Pseudomonas aeruginosa, two-component system, starch and sucrose metabolism, and photosynthesis were closely related to the TCS-induced growth inhibition in the 0.5 µg/L TCS treatment. Photosynthesis systems and potentially two-component system were identified to be sensitive targets of TCS toxicity in A. flos-aquae. The present study provides novel insights on TCS toxicity at the transcriptomic level in A. flos-aquae.
Benzo[a]pyrene (BaP), a ubiquitous pollutant, raises environmental health concerns due to induction of bone toxicity in the unexposed offspring. Exposure of F0 ancestor medaka (Oryzias latipes) to 1 μg/L BaP for 21 days causes reduced vertebral bone thickness in the unexposed F3 male offspring. To reveal the inherited modifications, osteoblast (OB) abundance and molecular signaling pathways of transgenerational BaP-induced bone thinning were assessed. Histomorphometric analysis showed a reduction in OB abundance. Analyses of the miRNA and mRNA transcriptomes revealed the dysregulation of Wnt signaling (frzb/ola-miR-1–3p, sfrp5/ola-miR-96–5p/miR-455–5p) and bone morphogenetic protein (Bmp) signaling (bmp3/ola-miR-96–5p/miR-181b-5p/miR-199a-5p/miR-205–5p/miR-455–5p). Both pathways are major indicators of impaired bone formation, while the altered Rank signaling in osteoclasts (c-fos/miR-205–5p) suggests a potentially augmented bone resorption. Interestingly, a typical BaP-responsive pathway, the Nrf2-mediated oxidative stress response (gst/ola-miR-181b-5p/miR-199a-5p/miR-205), was also affected. Moreover, mRNA levels of epigenetic modification enzymes (e.g., hdac6, hdac7, kdm5b) were found dysregulated. The findings indicated that epigenetic factors (e.g., miRNAs, histone modifications) may directly regulate the expression of genes associated with transgenerational BaP bone toxicity and warrants further studies. The identified candidate genes and miRNAs may serve as potential biomarkers for BaP-induced bone disease and as indicators of historic exposures in wild fish for conservation purposes.
A recent study showed that erythromycin (ERY) exposure caused hormesis in a model alga (Raphidocelis subcapitata) where the growth was promoted at an environmentally realistic concentration (4 μg/L) but inhibited at two higher concentrations (80 and 120 μg/L), associated with opposite actions of certain signaling pathways (e.g., xenobiotic metabolism, DNA replication). However, these transcriptional alterations remain to be investigated and verified at the metabolomic level. This study uncovered metabolomic profiles and detailed toxic mechanisms of ERY in R. subcapitata using untargeted metabolomics. The metabolomic analysis showed that metabolomic pathways including ABC transporters, fatty acid biosynthesis and purine metabolism were associated with growth promotion in algae treated with 4 μg/L ERY. An overcompensation was possibly activated by the low level of ERY in algae where more resources were reallocated to efficiently restore the temporary impairments, ultimately leading to the outperformance of growth. By contrast, algal growth inhibition in the 80 and 120 μg/L ERY treatments was likely attributed to the dysfunction of metabolomic pathways related to ABC transporters, energy metabolism and metabolism of nucleosides. Apart from binding of ERY to the 50S subunit of ribosomes to inhibit protein translation as in bacteria, the data presented here indicate that inhibition of protein translation and growth performance of algae by ERY may also result from the suppression of amino acid biosynthesis and aminoacyl-tRNA biosynthesis. This study provides novel insights into the dose-dependent toxicity of ERY on R. subcapitata.
In this paper, we developed a sensor for on-site measuring beverage sucrose level based on cascade enzyme particles and a blood glucose meter. The cascade enzyme particles with sucrose hydrolyzing capability were prepared by co-precipitation of manganese carbonate, in which the stability of the enzymes was substantially enhanced by the particle encapsulation effect. The quantitative measurement of glucose produced by the hydrolysis of sucrose was performed using a commercial glucose meter, a commonly owned electrochemical device in homes, greatly improving detection accuracy and expanding applications. Actual sample testing demonstrated the high sensitivity and selectivity of the sensor, allowing for accurate detection of sucrose in beverages. This sensing strategy can also be further expanded to a variety of analytical assays, using blood glucose meters for portable quantitative testing.
A dual task was designed to involve a tracking mission with various tracking speeds and a spatial compatibility task with various signal-key mappings and presentation modalities. This dual task was used to investigate the effects of workload and resource competition in distinct parts of the dual-task process. The results demonstrated that increasing the tracking speed adversely affected the tracking performance but led to positive arousal to the secondary discrete response task. Visual spatial signals gave the shortest reaction time due to the optimal time-sharing of the visual resources in the focal and ambient channels. Compared with visual spatial signals, spatial signals of auditory and tactile modalities did not lead to an improved performance because of their cross-modality nature. These findings provided practical design guidelines for dual tasks in which the operators need to complete a continuous monitoring task visually and elicit timely and accurate responses to spatial information.
High strain hardening rate is usually pursued for high ductility. Here we report that moderate strain hardening rate is desired for producing better ductility and high yield strength, which is demonstrated in a medium carbon TRIP steel. By adjusting the temperature for bainitic transformation, the morphology, carbon content and residue stress of retained austenite were tuned to tailor the TRIP kinetics during tensile tests, which produced moderated but long-lasting strain hardening for high ductility while at the same time resulted in high yield strength. This strategy should work well for most materials, which usually have a limited ultimate strength. IMPACT STATEMENT A principle is proposed and verified that an optimized moderate strain hardening rate is desired to produce the best mechanical properties for metallic materials. ARTICLE HISTORY
Tuning the structural and electronic properties of halide perovskite material is an effective method to promote its device performance. Increasing the grain size can decrease grain boundaries and further reduce defects. Regulating the band structure will improve the separation and extraction efficiency of carriers. In this work, high-quality CsPbBr3 films with increased crystallinity, better preferential orientation and improved carrier dynamics are achieved, using partial wetting transparent monolayer graphene as an interlayer. It is demonstrated that graphene can partially shield the surface potential field of the substrates, resulting in a changed preferred orientation of the CsPbBr3. The reduced interaction between the substrates and the perovskite effectively decreases the diffusion barrier of adatoms, increasing the grain size and crystallinity. Besides, the presence of graphene also tunes the band structure of the perovskite with increased p-type doping, which changes the band offset at perovskite substrate interface. An improved charge extraction can be achieved on perovskite/G/ITO interface due to increased band offset while a reduced charge extraction is observed on perovskite/G/Au interface. As a result, the corresponding photodetector with graphene demonstrates better performance than that without graphene. Our study will provide more ideas for tuning the perovskite structure and energy bands to achieve better device performance.
In this paper, we propose a framework to generate diverse clustering solutions and conduct solution retrieval to improve performance. Specifically, we first project unlabelled data from multiple domains into a shared space while preserving the respective semantics. This space allows that representations of samples in a hard domain are recovered by a linear combination of those of others in the easy domains. Meanwhile, a clustering algorithm is adopted to provide pseudo labels for a conditional generative adversarial network to synthesize representations that in turn promote the learning of the above space. Second, we conduct the joint learning of feature projection and partition matrices on batches of representations, where the former ones are considered as clustering solutions and input into another generative adversarial network to generate more solutions. Third, we utilize the fusion of diffusion to effectively retrieve and extract the knowledge in multiple solutions to obtain the final clustering. We perform comparative experiments against other methods on multiple benchmark data sets. Experimental results demonstrate the effectiveness and superiority of our proposed method.
As the state-of-the-art energy storage technology, lithium-ion batteries have been attracting lots of attention, but their finite energy densities cannot satisfy the overwhelming demand for large energy storage and commercial flammable liquid electrolytes are also plagued by safety concerns. Solvent-free single-ion polymer electrolytes with excellent electrochemical properties are expected to solve these issues and enhance the energy density of the next-generation batteries technology. Here, we engineered the networking of a series of solvent-free anionic network polymer electrolytes to improve ionic transport for Li-metal battery applications. The anionic network polymers formed as a diamondoid structure consisting of borate anions bridged by branched ethylene glycol linkers of differing stoichiometric ratios, enabling the controlled segmental mobility of network polymers. The increasing segmental mobility offered an elevated ionic conductivity, revealing ionic transport was mostly controlled by engineering the segmental mobilities of polymers, especially at the given interanionic distance. However, there was a restricted ionic transport in fast segmental dynamics of the network polymers featuring free branches, implying that the branching would less contribute to ionic transport compared to the interanionic distance likely due to the frustration in changing the coordination site. Standout network polymer exhibited notable ion selectivity in Li+ cation transport and high oxidative stability. Galvanostatic cycling reveals outstanding resistance to dendrite growth, suggesting that the solvent-free network polymer can serve as a powerful electrolyte for Li-metal batteries.
Here, this work presents an air-stable ultrabright inverted organic light-emitting device (OLED) by using zinc ion-chelated polyethylenimine (PEI) as electron injection layer. The zinc chelation is demonstrated to increase the conductivity of the PEI by three orders of magnitude and passivate the polar amine groups. With these physicochemical properties, the inverted OLED shows a record-high external quantum efficiency of 10.0% at a high brightness of 45,610 cd m ⁻² and can deliver a maximum brightness of 121,865 cd m ⁻² . Besides, the inverted OLED is also demonstrated to possess an excellent air stability (humidity, 35%) with a half-brightness operating time of 541 h @ 1000 cd m ⁻² without any protection nor encapsulation.
In conventional ethylene carbonate (EC)/propylene carbonate (PC) electrolyte, sodium metal reacts spontaneously and deleteriously with solvent molecules. This significantly limits the practical feasibility of high-voltage sodium metal batteries based on Na metal chemistry. Herein, we present a sodium metal alloy strategy via introducing NaIn and Na 2 In phases in a Na/In/C composite, aiming at boosting Na ion deposition stability in the common EC/PC electrolyte. Symmetric cells with Na/In/C electrodes achieve an impressive long-term cycling capability at 1 mA cm ⁻² (> 870 h) and 5 mA cm ⁻² (> 560 h), respectively, with a capacity of 1 mAh cm ⁻² . In situ optical microscopy clearly unravels a stable Na ion dynamic deposition process on the Na/In/C composite electrode surface, attributing to a dendrite-free and smooth morphology. Furthermore, theoretical simulations reveal intrinsic mechanism for the reversible Na ion deposition behavior with the composite Na/In/C electrode. Upon pairing with a high-voltage NaVPOF cathode, Na/In/C anode illustrates a better suitability in SMBs. This work promises an alternative alloying strategy for enhancing Na metal interfacial stability in the common EC/PC electrolyte for their future applications.
Most technical trading strategies use the official closing price for analysis. But what is the effect when the official closing price is subject to market manipulation? This paper answers this question by testing the difference of profitabilities between using the official closing price and the last tick price. The results show a significant improvement of profitability by using the last tick price over the official closing price based on a data set in Hong Kong from 2011 to 2018.
The global community has been confronted with rising income inequality, in particular, for those least developed countries (LDCs), since the same level of inequality as in advanced countries would push many LDCs into abject poverty. This paper focuses on income inequality in developing countries, particularly LDCs. First, we demonstrate the infeasibility of fiscal measures in resolving income inequality even in developed countries. Second, we show that inequality in LDCs can be largely explained by urban-rural gap. Third, we uncover the benign impacts of urbanization on urban-rural gap. This leads us to propose an out-of-box strategy—containing income inequality by promoting well-managed urbanization. Fourth, we reveal a misperception that may have contributed to the neglect of urban-rural gap in constituting national inequality. This has possibly caused anti-urbanization mentalities and practices, with adverse distributional consequences. Finally, we provide evidence-based policy suggestions aimed at reducing income inequality and poverty—two major goals of SDGs.
Networks based on carbon nanotube (CNT) have been widely utilized to fabricate flexible electronic devices, but defects inevitably exist in these structures. In this study, we investigate the influence of the CNT-unit defects on the mechanical properties of a honeycomb CNT-based network, super carbon nanotube (SCNT), through molecular dynamics simulations. Results show that tensile strengths of the defective SCNTs are affected by the defect number, distribution continuity and orientation. Single-defect brings 0 ~ 25% reduction of the tensile strength with the dependency on defect position and the reduction is over 50% when the defect number increases to three. The distribution continuity induces up to 20% differences of tensile strengths for SCNTs with the same defect number. A smaller arranging angle of defects to the tensile direction leads to a higher tensile strength. Defective SCNTs possess various modes of stress concentration with different concentration degrees under the combined effect of defect number, arranging direction and continuity, for which the underlying mechanism can be explained by the effective crack length of the fracture mechanics. Fundamentally, the force transmission mode of the SCNT controls the influence of defects and the cases that breaking more force transmission paths cause larger decreases of tensile strengths. Defects are non-negligible factors of the mechanical properties of CNT-based networks and understanding the influence of defects on CNT-based networks is valuable to achieve the proper design of CNT-based electronic devices with better performances. Graphical Abstract
High-entropy ceramics (HECs) have shown great application potential under demanding conditions, such as high stresses and temperatures. However, the immense phase space poses great challenges for the rational design of new high-performance HECs. In this work, we develop machine-learning (ML) models to discover high-entropy ceramic carbides (HECCs). Built upon attributes of HECCs and their constituent precursors, our ML models demonstrate a high prediction accuracy (0.982). Using the well-trained ML models, we evaluate the single-phase probability of 90 HECCs that are not experimentally reported so far. Several of these predictions are validated by our experiments. We further establish the phase diagrams for non-equiatomic HECCs spanning the whole composition space by which the single-phase regime can be easily identified. Our ML models can predict both equiatomic and non-equiatomic HECs based solely on the chemical descriptors of constituent transition-metal-carbide precursors, which paves the way for the high-throughput design of HECCs with superior properties.
This article reports a highly integrated watch for noninvasive continual blood glucose monitoring. The watch employs a Nafion-coated flexible electrochemical sensor patch fixed on the watchband to obtain interstitial fluid (ISF) transdermally at the wrist. This reverse iontophoresis-based extraction method eliminates the pain and inconvenience that traditional fingerstick blood tests pose in diabetic patients’ lives, making continual blood glucose monitoring practical and easy. All electronic modules, including a rechargeable power source and other modules for signal processing and wireless transmission, are integrated onto a watch face-sized printed circuit board (PCB), enabling comfortable wearing of this continual glucose monitor. Real-time blood glucose levels are displayed on the LED screen of the watch and can also be checked with the smartphone user interface. With 23 volunteers, the watch demonstrated 84.34% clinical accuracy in the Clarke error grid analysis (zones A + B). In the near future, commercial products could be developed based on this lab-made prototype to provide the public with noninvasive continual glucose monitoring.
A compelling demand exists for high-performance high-temperature shape memory alloys (HTSMAs) that can be applied as intelligent components in the rapidly developing aerospace, robotics, manufacturing, and energy exploration industries. However, existing HTSMAs are handicapped by their high cost and unsatisfactory functional properties, which impede their practical application. Here, by using the strategy of creating an oligocrystalline structure, we have developed a high-performance, cost-effective high-temperature shape memory microwire exhibiting an exceptional combination of superb superelasticity with a large recoverable strain of up to 15%, an outstanding one-way shape memory effect with a maximum recoverable strain as high as 13% and a remarkable two-way shape memory effect with a large recoverable strain of 6.3%. These unparalleled comprehensive properties provide this microwire with a high potential for use in high-temperature actuation, sensing, and energy conversion applications, especially in miniature intelligent devices, such as high-temperature microelectromechanical systems. The present strategy may be universally applicable to other brittle phase-transforming alloys for achieving outstanding functional properties at high temperatures.
Origami has become an optimal methodological choice for creating complex three-dimensional (3D) structures and soft robots. The simple and low-cost origami-inspired folding assembly provides a new method for developing 3D soft robots, which is ideal for future intelligent robotic systems. Here, we present a series of materials, structural designs, and fabrication methods for developing independent, electrically controlled origami 3D soft robots for walking and soft manipulators. The 3D soft robots are based on soft actuators, which are multilayer structures with a dielectric elastomer (DE) film as the deformation layer and a laser-cut PET film as the supporting flexible frame. The triangular and rectangular design of the soft actuators allows them to be easily assembled into crawling soft robots and pyramidal- and square-shaped 3D structures. The crawling robot exhibits very stable crawling behaviors and can carry loads while walking. Inspired by origami folding, the pyramidal and square-shaped 3D soft robots exhibit programmable out-of-plane deformations and easy switching between two-dimensional (2D) and 3D structures. The electrically controllable origami deformation allows the 3D soft robots to be used as soft manipulators for grasping and precisely locking 3D objects. This work proves that origami-inspired fold-based assembly of DE actuators is a good reference for the development of soft actuators and future intelligent multifunctional soft robots.
The global pandemic of COVID-19 has caused huge causality and unquantifiable loss of social wealth. The innate immune response is the first line of defense against SARS-CoV-2 infection. However, strong inflammatory response associated with dysregulation of innate immunity causes severe acute respiratory syndrome (SARS) and death. In this review, we update the current knowledge on how SARS-CoV-2 modulates the host innate immune response for its evasion from host defense and its corresponding pathogenesis caused by cytokine storm. We emphasize Type I interferon response and the strategies of evading innate immune defense used by SARS-CoV-2. We also extensively discuss the cells and their function involved in the innate immune response and inflammatory response, as well as the promises and challenges of drugs targeting excessive inflammation for antiviral treatment. This review would help us to figure out the current challenge questions of SARS-CoV-2 infection on innate immunity and directions for future studies.
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11,995 members
Gajendra Kumar
  • Department of Neuroscience
Hon-Yeung Cheung
  • Department of Biomedical Sciences
Norman Tse
  • Division of Building Science and Technology
Ibrahim Elsohaby
  • Department of Infectious Diseases and Public Health
Carol Sze Ki Lin
  • School of Energy and Environment
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