Eosinophil-activating semiconducting polymer nanoparticles for cancer photo-immunotherapy

Eosinophils are important immune effector cells that affect T cell-mediated antitumor immunity. However, the low frequency and restrained activity of eosinophils restricted the outcome of cancer immunotherapies. We herein report an eosinophil-activating semiconducting polymer nanoparticle (SPNe) to improve photodynamic tumor immunogenicity, modulate eosinophil chemotaxis, and reinvigorate T-cell immunity for activated cancer photo-immunotherapy. SPNe comprises an amphiphilic semiconducting polymer and a dipeptidyl peptidase 4 (DPP4) inhibitor sitagliptin via a 1O2-cleavable thioketal linker. Upon localized NIR photoirradiation, SPNe generates 1O2 to elicit immunogenic cell death of tumors and induce specific activation of sitagliptin. The subsequent inhibition of DPP4 increases intratumoral CCL11 levels to promote eosinophil chemotaxis and activation. SPNe-mediated photo-immunotherapy synergized with immune checkpoint blockade greatly promotes tumor infiltration and activation of both eosinophils and T cells, effectively inhibiting tumor growth and metastasis. Thus, this study presents a generic polymeric nanoplatform to modulate specific immune cells for precision cancer immunotherapy.Ministry of Education (MOE)National Research Foundation (NRF)Submitted/Accepted versionK.P. thanks Singapore National Research Foundation (NRF) (NRF-NRFI07-2021-0005) and the Singapore Minis-try of Education, Academic Research Fund Tier 2 (MOE-T2EP30220-0010; MOE-T2EP30221-0004) for the financial support

Water activated skin adhesives

Bioadhesives have been gaining popularity as a result of the increased demand of management of wound closure and haemostasis, providing a minimally invasive wound closure method that can achieve scarless wound healing, unlike other conventional methods such as sutures or staples. However, bioadhesives have potential cytotoxicity and require further development on their adhesive strength, limiting its uses in clinical applications. This project aims to improve the bioadhesive properties, primarily adhesion strength, of 2,5 – Dihydroxybenzaldehyde grafted on branched polyethyleneimine (2,5 - DBA-g-PEI), a catechol-based bioadhesive where the catechol is activated by curing in water, by varying structure-property relationships (SPRs) that affect its bioadhesive properties. The formulation is based off a previously developed bioadhesive in the laboratory, PEI-DBA20 [1]. In order to determine how the SPRs affect 2,5 -DBA-g-PEI, lap shear tests, peel tests, and UV-vis spectroscopy are used. Lap shear tests showed that the catechol 2,5 – DBA was the best performing compared to other catechols when grafted on PEI, thus 2,5 – DBA-g-PEI was used for the project. Testing of other SPRs resulted in less optimal bioadhesive properties such as reduced adhesion strength or increased number of undesired types of failure (adherend). These SPRs include the reduction of lap shear rate, swelling of 2,5 – DBA-g-PEI in 1x PBS for extended periods of time, addition crosslinking/oxidizing agents, and increase of curing temperature. Although a number of SPRs tested reduced the adhesion strength rather than increasing it, further research can be done on other SPRs that affect the bioadhesive properties of 2,5 – DBA-g-PEI such as using other catechols or changing pH levels during curing to help advance the development of water-cured bioadhesives.Bachelor's degre

Protocol for photocatalytic upcycling of non-biodegradable plastics into platform chemicals at ambient conditions

Upcycling plastics presents an opportunity not only to reduce plastic waste, but also to provide an alternative carbon source to fossil fuels. Herein, we present a protocol to upcycle plastics with resin codes 2-7 using a commercially available base-metal photocatalyst. We first conducted batch reactions, followed by a continuous, segmented flow system for gram-scale upcycling into value-added platform chemicals. This protocol, employing tandem carbon-hydrogen bond oxidation/carbon-carbon bond cleavage reactions, can be useful for photocatalytically transforming plastics at ambient conditions. For complete details on the use and execution of this protocol, please refer to Li et al. (2023).Agency for Science, Technology and Research (A*STAR)Ministry of Education (MOE)Nanyang Technological UniversityNational Research Foundation (NRF)Published versionH.S.S. acknowledges that this project was supported by A*STAR under the AME IRG grant A2083c0050. H.S.S. thanks ExxonMobil for supporting this project through the Singapore Energy Center grant EM11161.TO24. H.S.S. also thanks the support from the Ministry of Education (Singapore) Academic Research Fund Tier 1 Grant RG 09/22 and the Nanyang Technological University (NTU) 5th Accelerating Creativity and Excellence Grant. H.S.S. acknowledges that this project was partly supported by the National Research Foundation (NRF) Singapore under the grant NRFCRP27-2021-0001

Piezoelectric reverse osmosis (RO) membrane: fabrication and anti-fouling effect

In this study, a novel piezoelectric RO membrane with vibrating mechanism when exposed to an electric field was developed. The vibration due to the piezoelectric effect can disturb the concentration polarization layer on the membrane surface and minimize membrane fouling. Polyvinylidene fluoride (PVDF) which has piezoelectric properties was selected as the porous substrate for a thin film composite (TFC) polyamide RO membrane in this study. Electrical poling was performed to enhance the piezoelectric properties of the PVDF substrate. RO membranes fabricated via interfacial polymerization using different PVDF substrates (i.e., with and without pre-wetting the PVDF substrate, with and without polyethylene terephthalate (PET) non-woven fabric support (denoted as NWF and no-NWF, respectively), with and without electrical poling) were systematically investigated. The results indicated that RO membrane fabricated on poled PVDF-NWF substrate shows reasonable pure water permeability of ∼2 LMH/bar and sodium chloride (NaCl, 2000 ppm) rejection of ∼98.9 % when tested at 15 bar. In the accelerated fouling study using colloidal silica particles (∼20 nm in diameter, 200 ppm with background of 2000 mg/L NaCl), when the RO membrane fabricated using both unpoled and poled PVDF-NWF substrates were excited with AC signal, membrane fouling was significantly reduced. These findings suggested that electrical poling may not be necessary for such piezoelectric RO membrane.National Research Foundation (NRF)Public Utilities Board (PUB)This research is supported by the National Research Foundation, Singapore, and PUB, Singapore’s National Water Agency under its RIE2025 Urban Solutions and Sustainability (USS) (Water) Centre of Excellence (CoE) Programme which provides funding to the Nanyang Environment & Water Research Institute (NEWRI) of the Nanyang Technological University, Singapore (NTU). Any opinions, findings and conclusions or recommendations expressed in this material are those of the author(s) and do not reflect the views of National Research Foundation, Singapore and PUB, Singapore’s National Water Agency

Mixed crystal FeFx submicron spheres loaded on fluorinated graphene as cathode materials for Lithium-Ion batteries

Iron fluoride (FeF3 and FeF2) is a potential candidate for the next generation of lithium-ion battery (LIBs) cathode materials due to their high theoretical specific capacity and low cost. However, previous studies have reported that the poor conductivity of FeF3 and FeF2 prevents their theoretical specific capacity from being effectively realized. Herein, fluorinated graphene loaded FeFx (FeFx@FG) submicron sphere was synthesized using graphene oxide and utilized as cathode materials for LIBs. Characterization by X-ray diffraction and transmission electron microscopy confirmed that the synthesized FeFx (x = 2 and 3) contains mixed FeF3 and FeF2crystals. The mixed crystal structure enables the FeFx@FG submicron sphere composite to display two steps in the electrochemical reaction when FeF3 and FeF2 discharge cooperatively, leading to excellent discharge performance. In addition, since the FG prepared by acid thermal method has good conductivity, it can significantly improve the FeFx conductivity and specific capacity when being connected to FG via C-F bond. The electrochemical tests show that the initial discharge capacity of FeFx@FG is as high as 394.24 mAh/g at the rate of 0.2C in the range of 1.5–4.0 V at 25 °C and display an excellent discharge capacity retention rate after the first discharge process, showing great potential of the mixed crystalline iron fluoride cathode in the field of lithium-ion batteries.Financial support from the National Natural Science Foundation of China (No. 21676216, 22075046, 51972063), Natural Science Funds for Distinguished Young Scholar of Fujian Province (2020 J06038), Special project of Shaanxi Provincial Education Department, China (20JC034), Basic research program of Natural Science in Shaanxi Province, China (2024JC-JCQN-19, 2019JM-294) are gratefully acknowledged

Lessons from applying SRGAN on Sentinel-2 images for LULC classification

Satellite images are commonly used to monitor land use land cover (LULC) changes. Unfortunately, publicly available images often lack the resolution required for detailed urban studies. In this study, we enhanced the resolution of Sentinel-2 (S2) satellite images from 10 meters to 2.5 meters using two super-resolution models: Real-SR and Real-ESRGAN. We tested the suitability of the enhanced images for LULC classification of an urban city, Singapore. From our results, colors have mostly been preserved and man-made objects have become sharper. However, the enhanced images also exhibit colour change, darkening, and salt-and-pepper effects. At this stage, there is no conclusive evidence that enhanced images can improve LULC classification. In fact, they have worsened classification accuracy by 17 - 30%, and the Kappa coefficient by 0.2 - 0.4. Although our application of super-resolution on LULC classification is not successful, it is a first attempt and could be further improved.National Research Foundation (NRF)Submitted/Accepted versionThis research/project is supported by the Catalyst: Strategic Fund from Government Funding, administered by the Ministry of Business Innovation & Employment, New Zealand under contract C09X1923, as well as the National Research Foundation, Singapore under its Industry Alignment Fund – Pre-positioning (IAF-PP) Funding Initiative

Tracing curves in the plane: geometric-invariant learning from human demonstrations

The empirical laws governing human-curvilinear movements have been studied using various relationships, including minimum jerk, the 2/3 power law, and the piecewise power law. These laws quantify the speed-curvature relationships of human movements during curve tracing using critical speed and curvature as regressors. In this work, we provide a reservoir computing-based framework that can learn and reproduce human-like movements. Specifically, the geometric invariance of the observations, i.e., lateral distance from the closest point on the curve, instantaneous velocity, and curvature, when viewed from the moving frame of reference, are exploited to train the reservoir system. The artificially produced movements are evaluated using the power law to assess whether they are indistinguishable from their human counterparts. The generalisation capabilities of the trained reservoir to curves that have not been used during training are also shown.National Research Foundation (NRF)Published versionThis research is supported by the National Research Foundation, Singapore, under the NRF Medium Sized Centre scheme (CARTIN)

Investigating the photodegradation mechanism and effects of excess iodide on the photostability of all-inorganic lead halide perovskite

Perovskite solar cells (PSCs) have risen in popularity following its rapid advancement in performance over the years since its invention in 2009. Hybrid PSCs such as MA/FAPbI3 have exhibited excellent power conversion efficiency (PCE) and good intrinsic stability, but do however suffer greatly from its poor extrinsic stability. Although lacking behind in performance, scientists have gravitated towards the use of all-inorganic PSCs due to its excellent extrinsic stability over its hybrid counterparts, particularly CsPbI3 mainly due to its suitable bandgap (~1.7eV). However, all-inorganic PSCs still suffer from poor phase stability and much research have been carried out to improving intrinsic stability, whereas little attention have been placed on its extrinsic stability, especially its photostability. Herein, we aim to investigate the full photodegradation reaction and mechanism of CsPbI3, as well as to identify the products formed from the photodegradation of the perovskite. When exposed to light for a prolonged duration, we have shown that CsPbI3 perovskite film will undergo photodegradation to form cesium iodide (CsI) crystals and an intermediate product of lead iodide (PbI2), before it undergoes further photodegradation to form lead (Pb0) metal and iodine (I2). With regards to the photodegradation mechanism, we propose that photodegradation is driven by the ion migration of iodide anions (I-), which drives the formation of I2 and more anionic vacancies, ultimately resulting in the formation of Pb0 metal. When excess I- and thiocyanate anions (SCN-) were added to reduce the ion migration of the existing I- present in the lattice, it is shown that the photostability of CsPbI3 generally improves, however only with the addition of an adequate amount of excess anions, whereas any insufficient or excess anions present in the lattice is shown to be detrimental towards the photostability of CsPbI3. This is likely attributed by the lack of anions added to passivate all the anionic vacancies or due to the surplus of anions that are incorporated the lattice, resulting in the formation of interstitial defects. Hence, calculation of the intrinsic defect density or judicious optimisations with respect to the quality of the perovskite films may prove to be a useful method to accurately determine the appropriate amount of additives to add, in order to effectively passivate all vacancy defects and ultimately improving the photostability of the perovskite film.Bachelor's degre

Financial portfolio optimization: an autoregressive deep reinforcement learning algorithm with learned intrinsic rewards

Deep Reinforcement Learning (DRL) has had notable success in sequential learning tasks in applied settings involving high-dimensional state-action spaces, sparking the interest of the finance research community. DRL strategies have been applied to the classical portfolio optimization problem − a dynamic, inter-temporal process of determining optimal portfolio allocations to maximize long-run returns. However, all existing DRL portfolio management strategies overlook the underlying interdependencies between subactions that exist in this specific task. We propose a unified framework of 2 existing concepts − autoregressive DRL architectures and learned intrinsic rewards − in order to integrate the benefits of modelling subaction dependencies and modifying the reward function to guide learning. We backtest our proposed strategy against 7 other benchmark strategies, and empirically demonstrate that ours achieves the best risk-adjusted returns. Most remarkably, from median testing results, our proposed strategy is 1 of only 2 approaches that beat market returns, while being exposed to less than a third of market risk. Moreover, we provide insights on the effects of learned intrinsic rewards against the backdrop of the autoregressive DRL architecture, which enables individual intrinsic rewards to be learned at the level of subactions, potentially addressing the credit assignment problem in RL.Bachelor's degre

From digital visual effects to emerging in-camera visual effects: investigating the change of workflow, occupational roles and common challenges in Southeast Asian and East Asian countries

In-camera Visual Effects (ICVFX) occupy an intermediate position between film and game production. It is an emerging filmmaking technique that combines traditional cinematography and motion tracking technologies with a real-time game engine and computer-generated imagery (CGI). This allows actors to perform against a real-time generated background displayed by an LED wall, enabling the film production crew to view the scene and deliver a close-to-final product on set. ICVFX has been widely embraced not only by Hollywood but also by the East Asian (EA) and Southeast Asian (SEA) production industries. This research aims to investigate the impact of ICVFX on workflow, occupational roles, and shared challenges occurring in EA and SEA-based production companies. Compared to green screen VFX production, the ICVFX workflow offers an iterative and interactive process supported by real-time technology. It seamlessly integrates filmmaking, game development, and LED wall-related methodologies. The workflow begins with film pre-production methods and progresses through two phases of game engine-oriented creation, followed by two LED wall-related review and rehearsal phases before principal photography. As a result, the demand for match-move and roto departments, prevalent in green screen VFX production, is significantly reduced. Additionally, instead of replacing the green screen, ICVFX is considered a distinct method with its own workflow features. With its advantages, limitations, and applications, ICVFX production serves as an alternative tool instead of fully replacing the green screen. Concomitantly, ICVFX transforms the departmental landscape by introducing new departments and roles responsible for the entire production. These include the Virtual Production (VP) supervisor, the virtual art denepartment (VAD), and the "Brain Bar." This study investigates occupational changes by examining four key roles from each production technique. To adapt to ICVFX, the VFX supervisor must work closely with the VP crew led by the VP supervisor; the environment artist transforms into the VAD artist; the VFX compositor and technical director become part of the "Brain Bar." This transformation creates a demand for technical artists (TA) and requires the artists to be versatile and able to work “live” with on-set communication styles. With an understanding of the new workflow and occupational roles, this study pays equal attention to the ICVFX industry in EA and SEA countries. Five main challenges are observed and analysed from sampled interviews, highlighting a different industry landscape compared to Hollywood. Furthermore, industry and academic-related suggestions and recommendations are provided to address these challenges.Master's degre