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The shift towards renewable energy mix has resulted in an exponential growth of the photovoltaic (PV) industry over the past few decades. Parallelly, new recycling technology developments are required to address the incoming volume of waste as they gradually approach their end-of-life (EoL) to realize the concept of a circular economy. Typical recycling processes involve high-temperature burning for separation and release of the PV cells for metal recovery processes. However, this thermal process generates gaseous by-products that cause serious health and environmental issues. Eschewing the need for burning, we demonstrate a simple crush-and-sieve methodology to strategically aids the separation of polymeric and metallic contents. The proposed approach showcased the efficient size-selective separation and generated polymer- and metal-rich fractions. More than 90 % of the total polymer present within the studied wastes was found to be retained in larger sized-particle fractions (F1 and F2). Metal content analysis highlighted the enrichment of highly valuable silver into the smallest sized-particle fraction (F4), accounting up to 70 % and 80 % of total silver present respectively for EVAc and MP. The benefits ripe through this simple crush-and-sieve method offers an attractive pathway for PV recycling process to obtain metal-rich fractions and allow focused recovery of valuable materials through an environmentally friendlier manner. National Environmental Agency (NEA) National Research Foundation (NRF) This research/project is supported by the National Research Foundation, Singapore, and National Environment Agency, Singapore under its Closing the Waste Loop Funding Initiative (Award No. USS-IF-2018- 4).

Chemical recycling of poly (ethylene terephthalate) (PET) by depolymerization into monomers to recreate virgin-grade plastics is desirable; however, the energy inefficient separation and purification steps needed to obtain high-purity monomers result in poor overall economic feasibility at present. Herein, we present a one-step integrated process for partial depolymerization and upcycling of PET oligomers directly in to high-value product without any need for solvent recovery and purification. The key strategy for our approach is using multifunctional cleaving agents such as glycerol in the presence of ionic liquid as a catalyst for controlled partial depolymerization of PET via transesterification using N-Methyl-2-pyrrolidone (NMP) as solvent. The obtained depolymerized, oligomeric PET (DOPET) recyclate together with NMP and IL is a gel-like, ionic-conductive material, also termed as an “ionogel”, that has the potential to be used in energy storage applications or as mechanically robust electrical conductors. This is a one-step process requiring no extensive separation and purification of PET oligomers or distillation of solvent for recovery which further simplifies the recycling process while simultaneously increasing the value of the waste product. We have further investigated the effects of the choice and amount of cleaving agent on the molecular weight and branching of the DOPET oligomers and hence the properties of the upcycled end products. Moreover, we have also shown the versatility of the abovementioned process for controlled depolymerization of other condensation polymers such as polyamides, polyurethane, and even mixed polymer products to obtain high value functional materials. Submitted/Accepted version

Urban infrastructures are invariably constituted by social and technical components whose capacity to withstand crisis is determined by the resilience of their sociotechnical structures. This study aims to apply the principles of sociotechnical resilience in modeling and simulating disaster response in urban areas. Drawing on a case study of Jakarta, Indonesia, our study focuses on the role of hospitals as part of healthcare infrastructure in response to a large-scale disaster. Each hospital is modeled as a coordinated location with a certain amount of resources, primarily in terms of medical staff. We perform sensitivity analysis through Monte Carlo simulations to observe the impacts of various response strategies, disaster severity, and communication duration on system resilience. The results show that centralized systems are generally more suitable for dealing with low disaster severity, while the decentralized strategy performs better during a disaster with worse impacts. Additionally, the time taken for communication and coordination can significantly affect the performance of centralized systems. By simulating various scenarios, parameters, and recovery protocols, the model we developed can help policymakers, city planners, and other stakeholders design proper response strategies suitable to their structural conditions and available resources during a large-scale disaster in urban cities. Ministry of Education (MOE) National Research Foundation (NRF) Published version This work is an outcome of the Future Resilient Systems project at the Singapore-ETH Centre (SEC), which was funded by the National Research Foundation of Singapore (NRF) under its Campus for Research Excellence and Technological Enterprise (CREATE) programme (FI 370074011). Sulfikar Amir received additional research support from Singapore Ministry of Education’s Academic Research Fund Tier-1 Grant Number RG53/19 (NS).

Class-incremental learning (CIL) on multivariate time series (MTS) is an important yet understudied problem. Based on practical privacy-sensitive circumstances, we propose a novel distillation-based strategy using a single-headed classifier without saving historical samples. We propose to exploit Soft-Dynamic Time Warping (Soft-DTW) for knowledge distillation, which aligns the feature maps along the temporal dimension before calculating the discrepancy. Compared with Euclidean distance, Soft-DTW shows its advantages in overcoming catastrophic forgetting and balancing the stability-plasticity dilemma. We construct two novel MTS-CIL benchmarks for comprehensive experiments. Combined with a prototype augmentation strategy, our framework demonstrates significant superiority over other prominent exemplar-free algorithms. National Research Foundation (NRF) Submitted/Accepted version This research is part of the programme DesCartes and is supported by the National Research Foundation, Prime Minister’s Office, Singapore under its Campus for Research Excellence and Technological Enterprise (CREATE) programme.

Existing solutions to zero-shot text classification either conduct prompting with pre-trained language models, which is sensitive to the choices of templates, or rely on large-scale annotated data of relevant tasks for meta-tuning. In this work, we propose a new paradigm based on self-supervised learning to solve zero-shot text classification tasks by tuning the language models with unlabeled data, called self-supervised tuning. By exploring the inherent structure of free texts, we propose a new learning objective called first sentence prediction to bridge the gap between unlabeled data and text classification tasks. After tuning the model to learn to predict the first sentence in a paragraph based on the rest, the model is able to conduct zero-shot inference on unseen tasks such as topic classification and sentiment analysis. Experimental results show that our model outperforms the state-of-the-art baselines on 7 out of 10 tasks. Moreover, the analysis reveals that our model is less sensitive to the prompt design. Our code and pre-trained models are publicly available at https://github.com/DAMO-NLP-SG/SSTuning ., Accepted to the Findings of ACL 2023

The reaction kinetics of spin-polarized oxygen evolution reaction (OER) can be enhanced by ferromagnetic (FM) catalysts under an external magnetic field. However, applying a magnetic field necessitates additional energy consumption and creates design difficulties for OER. Herein, we demonstrate that a single-domain FM catalyst without external magnetic fields exhibits a similar OER increment to its magnetized multi-domain one. The evidence is given by comparing the pH-dependent increment of OER on multi- and single-domain FM catalysts with or without a magnetic field. The intrinsic activity of a single-domain catalyst is higher than that of a multi-domain counterpart. The latter can be promoted to approach the former by the magnetization effect. Reducing the FM catalyst size into the single-domain region, the spin-polarized OER performance can be achieved without a magnetic field, illustrating an external magnetic field is not a requirement to reap the benefits of magnetic catalysts. Ministry of Education (MOE) National Research Foundation (NRF) Submitted/Accepted version This work is supported by the Singapore MOE Tier 2 grant (MOE-T2EP10220-0001) and the Singapore National Research Foundation under its Campus for Research Excellence and Technological Enterprise (CREATE) programme.

Defect management strategies are vital for enhancing the performance of perovskite-based optoelectronic devices, such as perovskite-based light-emitting diodes (PeLEDs). As additives can fucntion both as acrystallization modifier and/or defect passivator, a thorough study on the roles of additives is essential, especially for blue emissive Pe-LEDs, where the emission is strictly controlled by the n-domain distribution of the Ruddlesden–Popper (RP, L2An–1PbnX3n+1, where L refers to a bulky cation, while A and X are monovalent cation, and halide anion, respectively) perovskite films. Of the various additives that are available, octyl phosphonic acid (OPA) is of immense interest because of its ability to bind with uncoordinated Pb2+ ( notorious for nonradiative recombination) and therefore passivates them. Here, with the help of various spectroscopic techniques, such as X-ray photon-spectroscopy (XPS), Fourier-transform infrared spectroscopy (FTIR), and photoluminescence quantum yield (PLQY) measurements, we demonstrate the capability of OPA to bind and passivate unpaired Pb2+ defect sites. Modification to crystallization promoting higher n-domain formation is also observed from steady-state and transient absorption (TA) measurements. With OPA treatment, both the PLQY and EQE of the corresponding PeLED showed improvements up to 53% and 3.7% at peak emission wavelength of 485 nm, respectively. Ministry of Education (MOE) National Research Foundation (NRF) Submitted/Accepted version This research was funded by National Research Foundation (NRF), Prime Minister’s Office, Singapore under its Competitive Research Programme (CRP Award NRFCRP14-2014-03) and Ministry of Education, Singapore (MOE2019-T2-2-097). The photophysics studies were supported by the grants funded by the Singapore Ministry of Education under its AcRF Tier 2 grant (MOE-T2EP50120- 0004) and the NRF under NRF Investigatorship (NRF-NRFI2018-04).

Organic-inorganic perovskite solar cells demonstrate immense potential for future photovoltaic application due to their remarkable efficiency advancements competitively low-cost. To unlock the full capability of perovskite, developments to the neighbouring layers play immense roles in the ultimate performance of a perovskite solar device. Here, a brief review comprising of the advancements and roles of electron transport layers (ETLs) is discussed. In addition, the effects of ETL on the charge transport, hysteresis, and stability of perovskite solar devices, along with high−performing examples, are also explored. Ministry of Education (MOE) Submitted/Accepted version The research is supported by AcRF Tier2 grant (MOE-T2EP50121-0012) from Singapore Ministry of Education.

Osmotically assisted reverse osmosis (OARO) has shown great potential for low-cost and energy-efficient brine management. However, its performance can be significantly limited by membrane fouling. Here, we performed for the first time a comprehensive study on OARO membrane fouling, explored the associated fouling mechanisms, and evaluated fouling reversibility via simple physical cleaning strategies. First, internal membrane fouling at the draw (permeate) side was shown to be insignificant. Flux behavior in short-term operation was correlated to both the evolution of fouling and the change of internal concentration polarization. In long-term operation, membrane fouling constrained the OARO water flux to a singular, common upper limit, in terms of limiting flux, which was demonstrated to be independent of operating pressures and membrane properties. Generally, once the limiting flux was exceeded, the OARO process performance could not be improved by higher-pressure operation or by utilizing more permeable and selective membranes. Instead, different cyclic cleaning strategies were shown to be more promising alternatives for improving performance. While both surface flushing and osmotic backwashing (OB) were found to be highly effective when using pure water, a full flux recovery could not be achieved when a nonpure solution was used during OB due to severe internal clogging during OB. All in all, the presented findings provided significant implications for OARO operation and fouling control. Nanyang Technological University This research was supported by the Start-up Grant (SUG #002195-00001) for Q.S. from Nanyang Technological University. Furthermore, C.D. Peters and N.P. Hankins are grateful to the University of Bahrain (in the Kingdom of Bahrain) for granting a full scholarship to C.D. Peters.

Non-hemolytic antimicrobial peptides (AMPs) are vital lead molecules for the designing and development of peptide-based antibiotics. Thanatin a 21-amino acid long single disulfide bonded AMP is known to be highly non-hemolytic with a limited toxicity to human cells and model animals. Thanatin demonstrates a potent antibacterial activity against multidrug-resistant Gram-negative pathogens. A single mutated variant of thanatin replaced last residue Met21 to Phe or thanatin M21F has recently been found to be more active compared to the native peptide. In order to gain mechanistic insights toward bacterial cell lysis versus non-hemolysis, here, we report atomic resolution structure and mode insertion of thanatinM21F reconstituted into zwitterionic detergent micelle by use of solution NMR spectroscopy. The 3D structure of thanatinM21F in DPC micelle is defined by an anti-parallel β-sheet between residues I9-F21 with a central cationic loop, residues N12-R14. PRE NMR studies revealed hydrophobic core residues of thanatinM21F are deeply inserted in the DPC micelle, while residues at the extended N-terminal half of the peptide are appeared to be mostly surface localized. Marked structural differences of thanatin and thanatinM21F in negatively charged LPS and DPC micelle could be correlated with non-hemolytic and antibacterial activity. Ministry of Education (MOE) This work has been supported by the Ministry of Education (MOE), Singapore.

A common view is that marginalized groups benefit substantially from strategic use of digital technologies. An intersectionality perspective, however, suggests that these outcomes may vary depending on individuals’ social positionality. We propose the concept of “subverted agency” to emphasize that use of digital technologies may be personally empowering but might reinforce normative regimes contributing to sociostructural marginalization. We investigated digital practices of 17 online-soliciting transfeminine sex workers through semi-structured interviews in Singapore, where attitudes toward gender diversity and sex work remain conservative. We highlight three dilemmas of digital media environments, namely, presentation of gender identity and embodiment, intimate relationships characterized by persistent liminality, and competitive pressures related to authenticity of identity. The subverted agency perspective suggests that digital practices do not straightforwardly transform unequal sociostructural conditions; instead, it offers a frame to rethink inclusion by attending to contextual intersections of marginalization. Nanyang Technological University The study was funded by a grant from Wee Kim Wee School of Communication and Information, Nanyang Technological University.

Extending halide perovskites' optoelectronic properties to stimuli-responsive chromism enables switchable optoelectronics, information display, and smart window applications. Here, we demonstrate a band gap tunability (chromism) via crystal structure transformation from three-dimensional FAPbBr3 to a ⟨110⟩ oriented FAn+2PbnBr3n+2 structure using a mono-halide/cation composition (FA/Pb) tuning. Furthermore, we illustrate reversible photochromism in halide perovskite by modulating the intermediate n phase in the FAn+2PbnBr3n+2 structure, enabling greater control of the optical band gap and luminescence of a ⟨110⟩ oriented mono-halide/cation perovskite. Proton transfer reaction-mass spectroscopy carried out to precisely quantify the decomposition product reveals that the organic solvent in the film is a key contributor to the structural transformation and, therefore, the chromism in the ⟨110⟩ structure. These intermediate n phases (2 ≤ n ≤ ∞) stabilize in metastable states in the FAn+2PbnBr3n+2 system, which is accessible via strain or optical or thermal input. The structure reversibility in the ⟨110⟩ perovskite allowed us to demonstrate a class of photochromic sensors capable of self-adaptation to lighting. Ministry of Education (MOE) National Research Foundation (NRF) Accepted version This research was funded by National Research Foundation, Prime Minister’s Office, Singapore, under its Competitive Research Programme (CRP Award No. NRF-CRP14-2014-03) and Ministry of Education, Singapore (MOE2019-T2-2-097).

Phenylpropanoid sucrose esters (PSEs) are plant-derived metabolites that exist widely in medicinal plants and possess important bioactivities. Their precise synthesis is challenging due to the distinct and diverse substitution patterns at the sugar framework, and it is scarcely reported. Orthogonal protection/deprotection strategies for disaccharides are more complex and less developed than those for monosaccharides. We disclose a precise synthesis of PSEs starting from 2,1′:4,6-di-O-diisopropylidene sucrose 7via an orthogonal protection/deprotection and selective cinnamoylation strategy. We demonstrate the strategy for the synthesis of several PSEs cinnamoylated at the O-3 and O-4′ positions of diisopropylidene sucrose 7. The strategy is enabled by a carefully selected and synergistic set of protecting groups and deprotecting agents under the optimized conditions. It potentially gives access to the ∼150 reported PSEs and opens the door for the custom synthesis of unnatural PSEs for industrial applications. The reported work also presents a viable strategy for the general orthogonal protection/deprotection of disaccharides for the precise synthesis of other classes of phenylpropanoid esters and related compounds. Nanyang Technological University Published version We thank the Interdisciplinary Graduate School and the School of Chemical and Biomedical Engineering, Nanyang Technological University, Singapore for financial support (CoE, Startup Grant).

Mixed species biofilms exhibit increased tolerance to numerous stresses compared to single species biofilms. The aim of this study was to examine the effect of grazing by the heterotrophic protist, Tetrahymena pyriformis, on a mixed species biofilm consisting of Pseudomonas aeruginosa, Pseudomonas protegens, and Klebsiella pneumoniae. Protozoan grazing significantly reduced the single species K. pneumoniae biofilm, and the single species P. protegens biofilm was also sensitive to grazing. In contrast, P. aeruginosa biofilms were resistant to predation. This resistance protected the otherwise sensitive members of the mixed species biofilm consortium. Rhamnolipids produced by P. aeruginosa were shown to be the primary toxic factor for T. pyriformis. However, a rhamnolipid-deficient mutant of P. aeruginosa (P. aeruginosa ΔrhlAB) maintained grazing resistance in the biofilm, suggesting the presence of at least one additional protective mechanism. P. aeruginosa with a deleted gene encoding the type III secretion system also resisted grazing. A transposon library was generated in the ΔrhlAB mutant to identify the additional factor involved in community biofilm protection. Results indicated that the Pseudomonas Quinolone Signal (PQS), a quorum sensing signaling molecule, was likely responsible for this effect. We confirmed this observation by showing that double mutants of ΔrhlAB and genes in the PQS biosynthetic operon lost grazing protection. We also showed that PQS was directly toxic to T. pyriformis. This study demonstrates that residing in a mixed species biofilm can be an advantageous strategy for grazing sensitive bacterial species, as P. aeruginosa confers community protection from protozoan grazing through multiple mechanisms. IMPORTANCE: Biofilms have been shown to protect bacterial cells from predation by protists. Biofilm studies have traditionally used single species systems, which have provided information on the mechanisms and regulation of biofilm formation and dispersal, and the effects of predation on these biofilms. However, biofilms in nature are comprised of multiple species. To better understand how multispecies biofilms are impacted by predation, a model mixed-species biofilm was here exposed to protozoan predation. We show that the grazing sensitive strains K. pneumonia and P. protogens gained associational resistance from the grazing resistant P. aeruginosa. Resistance was due to the secretion of rhamnolipids and quorum sensing molecule PQS. This work highlights the importance of using mixed species systems. Ministry of Education (MOE) Nanyang Technological University National Research Foundation (NRF) Published version We acknowledge the financial support from National Research Foundation and Ministry of Education Singapore under its Research Centre of Excellence Program. This work was also supported by a grant from the Singapore Ministry of Education (MOE2019-T2-1-050) and Australian Research Council Discovery Project DP170100453. Siew Herng Chan and Yu Fen Goh were supported by the Interdisciplinary Graduate School in conjunction with the Singapore Centre for Environmental Life Sciences Engineering. We also wish to thank the ESCMID Study Group for Biofilms–ESGB for supporting Henriette Lyng Røders participation in Eurobiofilms 2015 with a travel grant.

Various topological laser concepts have recently enabled the demonstration of robust light-emitting devices that are immune to structural deformations and tolerant to fabrication imperfections. Current realizations of photonic cavities with topological boundaries are often limited by outcoupling issues or poor directionality and require complex design and fabrication that hinder operation at small wavelengths. Here we propose a topological cavity design based on interface states between two one-dimensional photonic crystals with distinct Zak phases. Using a few monolayers of solution-processed all-inorganic cesium lead halide perovskite quantum dots as the ultrathin gain medium, we demonstrate a lithography-free, vertical-emitting, low-threshold, and single-mode laser emitting in the green. We show that the topological laser, akin to vertical-cavity surface-emitting lasers (VCSELs), is robust against local perturbations of the multilayer structure. We argue that the design simplicity and reduction of the gain medium thickness enabled by the topological cavity make this architecture suitable for low-cost and efficient quantum dot vertical emitting lasers operating across the visible spectral region. Agency for Science, Technology and Research (A*STAR) Ministry of Education (MOE) National Research Foundation (NRF) Published version Research was supported by the A*STAR-AME programmatic fund on Nanoantenna Spatial Light Modulators for NextGen Display Technologies (Grant A18A7b0058), the Singapore Ministry of Education (MOE2016-T3-1-006), and the Quantum Engineering Programme of the Singapore National Research Foundation (NRF2021- QEP2-01-P01).

In recent years, brine management in seawater reverse osmosis (SWRO) desalination has been more emphasized to reduce environmental hazards and recover valuable resources. However, current brine treatment methods are often hindered by the high brine concentration and energy consumption. To mitigate these challenges, this work applies a diafiltration-nanofiltration-reverse osmosis (DiaNF-RO) process, which aims to achieve divalent-monovalent ion separation in the pre-treatment step prior to RO. The diafiltration process is to enhance the separation performance of NF stage, while the RO stage is to produce the desalinated water and the diluent required by the diafiltration process. This study would justify the benefits of pre-treatment method (i.e., DiaNF-RO) over post-treatment method (i.e., RO-DiaNF), Fig. 1, in brine management by comparing the processes in 3 aspects (i.e., performance, operation, economic) via practical simulations, including pressure drop within module and concentration polarization (CP) effect, at the same number of stages and system water recovery, under similar input conditions such as NF/RO pressures and NF recovery rates. As shown in Table 1, compared to RO-DiaNF, the DiaNF-RO has better Mg-Na ion separation factor (SF) in both NF and RO brines; higher Na dilution in NF brine; lower RO area requirement; larger potential to operate at higher pressure and recovery due to lower osmotic pressure difference at membrane stages; less total operating cost especially with more stages due to more RO area saving. Overall, the pre-treatment DiaNF-RO achieves better results in performance, operation, and economic than the conventional post-treatment RO-DiaNF. 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).

Conventional organic solvent recovery is energy intensive and challenged by large footprint and complex operation and maintenance. To enable a more circular and sustainable pharmaceutical production, we amalgamate adsorption and membrane processes to address current Achilles heels in organic solvent recovery. In this work, we have successfully designed a polyacrylonitrile (PAN) electrospun membrane as scaffold to incorporate nanomaterial adsorbents in a layer-by-layer hierarchical structure. The porous nanofibrous morphology and layer-by-layer design, which deconstructs the adsorbent layers, help reduce the transport resistance of the isopropyl alcohol (IPA), leading to higher processing capacity at lower applied pressure, while maintaining the removal rates. To bring about versatility for different contaminants, we incorporated two different nanomaterials, namely positively charged metal-organic frameworks (MOFs), particularly MIL-101(Cr), and negatively charged functionalized multi-walled carbon nanotubes (MWCNTs) as powdered adsorbents, for the extraction of anionic and cationic dyes, respectively. Our results show that the MOF-based membrane scaffold can achieve 99% and 95% rose Bengal and methyl orange removal rates in IPA, respectively, while operating at a low operating pressure of 0.04 bar and delivering a processing capacity of 60 L m−2 h−1 of IPA, with good regeneration and recyclability of up to three cycles of removal process. On the other hand, the MWCNT-based membrane scaffold displays up to 90% methylene blue dye in IPA at 0.07 bar pressure and delivering a 40 L m−2 h−1 of IPA processing capacity in a single-cycle removal process. The promising recovery performance and facile tailoring of adsorbents to target contaminants of different charges render our adsorptive membrane scaffold process less energy intensive and highly versatile to meet various needs for solvent recovery in the pharmaceutical industry. National Research Foundation (NRF) Public Utilities Board (PUB) Submitted/Accepted version This research is supported by the National Research Foundation, Singapore, and implemented by the Public Utilities Board (PUB), Singapore’s National Water Agency, under its Competitive Funding for Water Research Funding Initiative (Grant Award CWR-2101-0010).

Advances in signal processing and machine learning have expedited electroencephalogram (EEG)-based emotion recognition research, and numerous EEG signal features have been investigated to detect or characterize human emotions. However, most studies in this area have used relatively small monocentric data and focused on a limited range of EEG features, making it difficult to compare the utility of different sets of EEG features for emotion recognition. This study addressed that by comparing the classification accuracy (performance) of a comprehensive range of EEG feature sets for identifying emotional states, in terms of valence and arousal. The classification accuracy of five EEG feature sets were investigated, including statistical features, fractal dimension (FD), Hjorth parameters, higher order spectra (HOS), and those derived using wavelet analysis. Performance was evaluated using two classifier methods, support vector machine (SVM) and classification and regression tree (CART), across five independent and publicly available datasets linking EEG to emotional states: MAHNOB-HCI, DEAP, SEED, AMIGOS, and DREAMER. The FD-CART feature-classification method attained the best mean classification accuracy for valence (85.06%) and arousal (84.55%) across the five datasets. The stability of these findings across the five different datasets also indicate that FD features derived from EEG data are reliable for emotion recognition. The results may lead to the possible development of an online feature extraction framework, thereby enabling the development of an EEG-based emotion recognition system in real time. Ministry of Education (MOE) Published version This research was financed by the Singapore Ministry of Education (MOE) through the Education Research Funding Programme (ERFP) (Grant No: PG 03/21 YR), which was overseen by the National Institute of Education (NIE), Nanyang Technological University (NTU), Singapore.

Coherent optical manipulation of exciton states provides a fascinating approach for quantum gating and ultrafast switching. However, their coherence time for incumbent semiconductors is highly susceptible to thermal decoherence and inhomogeneous broadening effects. Here, we uncover zero-field exciton quantum beating and anomalous temperature dependence of the exciton spin lifetimes in CsPbBr3 perovskite nanocrystals (NCs) ensembles. The quantum beating between two exciton fine-structure splitting (FSS) levels enables coherent ultrafast optical control of the excitonic degree of freedom. From the anomalous temperature dependence, we identify and fully parametrize all the regimes of exciton spin depolarization, finding that approaching room temperature, it is dominated by a motional narrowing process governed by the exciton multilevel coherence. Importantly, our results present an unambiguous full physical picture of the complex interplay of the underlying spin decoherence mechanisms. These intrinsic exciton FSS states in perovskite NCs present fresh opportunities for spin-based photonic quantum technologies. Ministry of Education (MOE) National Research Foundation (NRF) Published version NRF-CRP25-2020-0004

Hybrid organo-inorganic perovskites are a well-known material in the field of optoelectronic devices. They are easy to synthesize and scale, and due to the variability of composition, their properties are tunable. Until now, a significant problem in the use of this material is the environmental instability. Changing the composition of the layers by introducing copper complexes in place of an organic layer can help reduce the material degradation rate, change the optical properties, as well as add one more degree of freedom in their variability. The structure and phase transitions of hybrid perovskite with copper paddle-wheel clusters linking perovskite layers [Cu(O2C-(CH2)3-NH3)2]PbBr4 were investigated using Raman spectroscopy under variable pressure up to 17 GPa, furthermore in the temperature range between 80 K to 373 K. The following optical properties of the material are described: photoluminescence, the dependence of absorption on pressure. Primary DFT calculations have shown that the studied material can be considered as a three-component system in which energy transfers between components are possible. Based on them, further prospects for the study and application of copper-containing perovskite are proposed.

A fundamental understanding of the hot-carrier dynamics in halide perovskites is crucial for unlocking their prospects for next generation photovoltaics. Presently, a coherent picture of the hot carrier cooling process remains patchy due to temporally overlapping contributions from many-body interactions, multi-bands, band gap renormalization, Burstein-Moss shift etc. Pump-push-probe (PPP) spectroscopy recently emerges as a powerful tool complementing the ubiquitous pump-probe (PP) spectroscopy in the study of hot-carrier dynamics. However, limited information from PPP on the initial excitation density and carrier temperature curtails its full potential. Herein, this work bridges this gap in PPP with a unified model that retrieves these essential hot carrier metrics like initial carrier density and carrier temperature under the push conditions, thus permitting direct comparison with traditional PP spectroscopy. These results are well-fitted by the phonon bottleneck model, from which the longitudinal optical phonon scattering time τLO , for MAPbBr3 and MAPbI3 halide perovskite thin film samples are determined to be 240 ± 10 and 370 ± 10 fs, respectively. Ministry of Education (MOE) National Research Foundation (NRF) Submitted/Accepted version This research/project is supported by the Ministry of Education under its AcRF Tier 2 grants (MOE2019-T2-1-006, MOE-T2EP20120-0013 and MOE-T2EP50120-0004); and the National Research Foundation (NRF) Singapore under its NRF Investigatorship (NRF-NRFI2018-04).

Water quality monitoring plays an essential role in water resource management and water governance. At present, the monitoring is commonly conducted via in-situ sampling and/or by setting up gauging stations, which can be labour intensive and costly. Recently, the possibility of monitoring water quality through remote sensing with Unmanned Aerial Vehicles (UAVs) and hyperspectral sensors has shown great promise, with the key advantages of larger spatial coverage and possibly higher accuracy enabled by higher spectral resolution and more extensive data. Correspondingly, more advanced methods need to be established for hyperspectral analysis for water quality determination to capitalize on this wealth of information. In this study, a new method called Hierarchical Bayesian Model Aggregation for Optimal Multiple Band Ratio Analysis (HBMA-OMBRA) has been developed as a proof-of-concept for estimating Total Suspended Solids (TSS) concentrations from the hyperspectral data. The method leverages on the Bayesian ensembling of competing models because there is not a single best working model for all situations. It also encompasses a new approach called Ensemble Band Ratio Selection (ENBRAS) for the identification of best candidate band ratios (BBRs) via a set of ensembling and “bagging” procedures, followed by a modified Batchelor Wilkin's algorithm to cluster the candidate band ratios. A laboratory investigation was conducted in the present study to measure the hyperspectral reflectance in different experiments under various environmental conditions to verify the robustness of HBMA-OMBRA. From the experimental results, six distinct clusters of candidate BBRs were identified using ENBRAS. In particular, two clusters in the red, green, and near infrared spectrum showed the largest contribution. The significance of multi-clusters provides an explanation for previously contrasting results reported in the literature and some evidence for reconciling these findings. Public Utilities Board (PUB) Submitted/Accepted version We would like to thank Public Utilities of Singapore (PUB) – Singapore’s National Water Agency, for granting the scholarship and providing support to the first author.

Learned indexes have been proposed to replace classic index structures like B-Tree with machine learning (ML) models. They require to replace both the indexes and query processing algorithms currently deployed by the databases, and such a radical departure is likely to encounter challenges and obstacles. In contrast, we propose a fundamentally different way of using ML techniques to build a better R-Tree without the need to change the structure or query processing algorithms of traditional R-Tree. Specifically, we develop reinforcement learning (RL) based models to decide how to choose a subtree for insertion and how to split a node when building and updating an R-Tree, instead of relying on hand-crafted heuristic rules currently used by the R-Tree and its variants. Experiments on real and synthetic datasets with up to more than 100 million spatial objects show that our RL based index outperforms the R-Tree and its variants in terms of query processing time. Nanyang Technological University This work was supported by Alibaba Group through Alibaba Innovative Research (AIR) Program and Alibaba-NTU Singapore Joint Research Institute (JRI), Nanyang Technological University, Singapore.

Perovskite structure takes the empirical formula ABX3, whereas Double perovskites, or elpasolites, are the crystal structures in which the B position in ABX3 is equally occupied by two different cations. The usual compositions of Double perovskite structure are (1-3) type double perovskites, which means that the two B cations have +1 and +3 oxidation states. In the quest of making near infrared emitting halide perovskite quantum dots, the most commonly and most productive method for colloidal synthesis of nanocrystals, the hot injection method, was used. Target composition for such an application was Cs2PbSnI6. The synthesis process was optimized for reactant ratios to achieve the exact stoichiometry. But then, the usual characterization processes, such as powder X-ray Diffraction, Selected area electron diffraction (SAED) and STEM-EDX were not enough to convincingly prove that the structure thus formed was a double perovskite. The STEM EDX results can only explain the overall atomic ratio of an ensemble of nanocrystals (with a little error) as the issue of carbon contamination dominates at single nanocrystal level. Whereas lack of reference crystal structure and low amount of formed product in each synthesis batch contribute to inconclusive results in SAED and XRD and fail to answer the question, “Is it even a double perovskite structure? Or just a perovskite structure with non-periodic substitution or an ensemble of different crystals of different compositions?”. This problem seems evident in the literature as there seems no mention of any (2-2) type double perovskite structure. Which makes this work first to mention the properties, characteristics, and problems with (2-2) type double perovskite nanocrystals. A combination of advanced electron microscopy techniques and advanced X-ray diffraction techniques such as PDF refinement were used to tackle this problem. Some sample preparation tips and tricks for characterization are also explained for such a distinction. National Research Foundation (NRF)

Past studies by the authors have demonstrated the feasibility of utilizing municipal solid waste (MSW) incineration bottom ash (IBA) as an aerating agent to produce autoclaved aerated concrete (AAC). However, the gas generation potential of as-received IBA (General IBA) is significantly poorer than conventional aerating agents such as pure aluminum powder. The classification of IBA showed that coarse non-ferrous IBA fraction with particle size greater than 1.18 mm (CNF-IBA) contains a higher concentration of metallic aluminum. This study proposes specifically utilizing CNF- IBA fraction as an aerating agent to produce AAC. Two other AACs with pure Al powder and General IBA as aerating agents were investigated for systematic comparison. The aeration kinetics, fresh, and hardened properties were experimentally investigated. A novel approach is presented to study the influence of coordination between aeration extent and yield stress development on volume expansion capacity. The developed AAC with CNF-IBA exhibited the highest specific compressive strength. The leaching analysis showed that the usage of IBA as an aerating agent in AAC production is safe during the service life of AAC, and its demolished samples at the end of service time can be landfilled as inert material. National Environmental Agency (NEA) National Research Foundation (NRF) The authors would like to acknowledge financial support from the Environment Technology Research Program (ETRP), National Environment Agency (NEA), Singapore (ETRP 1301 104), and from the SinBerBEST program, National Research Foundation (NRF), Singapore.

Chemical bath deposition (CBD) is a common method to fabricate SnO2 electron-transport layers in perovskite solar cells. However, this typically requires long deposition times, a significant drawback for eventual commercialisation of perovskite solar cells. By applying ultrasonication during the chemical bath deposition process, higher rates of heterogenous nucleation were triggered which accelerated the CBD process without sacrificing coverage. Deposition times of 15min, 30min and 45min were investigated, and 30 minutes was determined to be the optimal duration for ultrasonication-assisted chemical bath deposition, with the current parameters. Ministry of Education (MOE) National Research Foundation (NRF) Published version This research was funded by National Research Foundation, Prime Minister’s Office, Singapore through the Intra-CREATE Collaborative Grant (NRF2018-ITC001-001), and Ministry of Education Tier 2 project (MOE2019-T2-2-097).

Ruddlesden-Popper perovskites (RPPs) have been demonstrated as a very promising approach for tuning the emission color of perovskite light-emitting diodes (PeLEDs). However, achieving high-performance red PeLEDs with recommendation 2020 color coordinates is still challenging due to the lack of reasonable control over the properties of RPP films. Here, we demonstrate that the judicious selection of spacer cations in RPPs affords a lever for engineering their film properties, including phase distribution, energy funneling process, trap density, and carrier mobility. Four structurally related spacer cations, benzylammonium (BZA), phenylethylammonium (PEA), 3-phenyl-1-propylammonium (PPA), and phenoxyethylammonium (POEA), are studied. Owing to narrow phase distribution, efficient energy funneling, and low trap density, the POEA-based RPP films enable efficient red PeLEDs with a peak external quantum efficiency of 10.3%, a maximum brightness of 1052 cd m−2, and excellent spectral stability. Significantly, the electroluminescence spectrum represents CIE 1931 color coordinates of (0.71, 0.29), which meets the recommendation 2020 standard (0.708, 0.292). The findings provide useful guidelines for the rational design of new organic spacer cations for RPPs with high performance. Agency for Science, Technology and Research (A*STAR) Published version This work is supported by the Agency For Science, Technology and Research (A*STAR), Singapore, under the National Robotics Program (NRP)-Robotics Domain Specific (RDS: Ref. [1922200001]).

The soil–water characteristic curve (SWCC) is one of the most crucial and fundamental soil properties in unsaturated soil mechanics. Many theories and equations have been developed to describe and best fit SWCC with unimodal or bimodal characteristics. In this study, a general best-fitting equation for SWCC with multimodal characteristics (bimodal and trimodal SWCC) is proposed. The parameters in the proposed equation are closely related to the properties of soil and variables in the SWCC. To evaluate the performance of the proposed equation in best-fitting multimodal SWCC that has more than two modalities, a trimodal SWCC soil mixture that consists of sand, kaolin and activated carbon has been prepared and tested in the laboratory in this study. The proposed equation has been evaluated with data from published literature and the newly developed soil mixture of trimodal SWCC. The proposed equation has shown high accuracy for best-fitting bimodal SWCC and trimodal SWCC. Nanyang Technological University Submitted/Accepted version This study was supported by a research scholarship from the Nanyang Environment & Water Research Institute (NEWRI) and Nanyang Technological University, Singapore.

Extant literature has found that poor self-esteem is linked to negative psychological well-being and adverse behavior. While various studies and arguments point to the potential benefits of using Virtual Reality (VR) to enhance self-esteem, the understanding toward the underlying mechanisms and their corresponding effects on self-evaluations is still not comprehensive. To this end, some research has suggested that embodiment of personalized avatars may induce self-related thoughts and self-awareness, which may influence self-esteem. Additionally, the Computers are Social Actors (CASA) paradigm suggests that humans may mindlessly respond to computers in ways that are similar to human interactions. Based on those assertions, it is plausible to assume that embodiment of a personalized avatar and interactions with a virtual human character may influence one’s self-evaluations. However, those effects on self-esteem have not been examined empirically in past studies. To address these research gaps, a 2 (avatar personalization: personalized vs. non-personalized avatar) × 2 (virtual human interaction quality: positive vs. negative) between-subjects experiment was conducted using a VR simulation (N = 171). Findings from the study showed that there were no main effects of avatar personalization and virtual human interaction quality on state self-esteem. However, the post-hoc analyses suggest that participants who embodied a personalized avatar experienced a positive change in state self-esteem from pre- to post-simulation, regardless of the virtual human interaction quality. These findings provide some preliminary indications that avatar personalization enabled through face mapping may enhance self-evaluations, but further research is needed to validate this finding. Submitted/Accepted version

Recent advances in nanotechnology have brought great opportunities to the developing next-generation nanofiltration membranes for addressing the concern of global water scarcity and energy crisis. Carbon dots have been deemed as a promising nanomaterial for enhancing the nanofiltration performance of polymeric membranes. Herein, carbon dots with cationic amine groups (PEI-CDs) and those with anionic sulfonate groups (PS-CDs) are incorporated into the polyamide selective layer of thin-film nanocomposite (TFN) membranes to create charged nanovoids (free volume) between the carbon dots and the surrounding polyamide network for high-efficiency nanofiltration. The positively charged amine group-based and negatively charged sulfonate group-based nanovoids in the resultant TFN-PEI-CDs and TFN-PS-CDs membranes, respectively, provide alternative pathways for efficient water permeation while effectively rejecting divalent ions via the Donnan and dielectric exclusion effects, thereby overcoming the recurring trade-off between permeability and selectivity encountered by dense polymeric membranes. In particular, the creation of negatively charged nanovoids enables the TFN-PS-CDs membrane to achieve one of the best performances among the recently reported nanofiltration membranes, by showing a nearly tripled pure water permeability of 30.9 L m−2 h−1 bar−1 as well as a higher Na2SO4 rejection rate of 99.4% than the membrane with a pristine polyamide selective layer. Moreover, the TFN membranes demonstrate greater resistance to foulants with charges of the same sign as the nanovoids. This work provides insights into the design of nanovoids with desired properties in other polymeric membranes for high-efficiency filtration processes. Nanyang Technological University The authors acknowledge the financial support from the Nanyang Environment and Water Research Institute (Core Funding), Nanyang Technological University, Singapore.

Many antibiotics are ineffective in killing Gram-negative bacteria due to the permeability barrier of the outer-membrane LPS. Infections caused by multi-drug-resistant Gram-negative pathogens require new antibiotics, which are often difficult to develop. Antibiotic potentiators disrupt outer-membrane LPS and can assist the entry of large-scaffold antibiotics to the bacterial targets. In this work, we designed a backbone-cyclized ultra-short, six-amino-acid-long (WKRKRY) peptide, termed cWY6 from LPS binding motif of β-boomerang bactericidal peptides. The cWY6 peptide does not exhibit any antimicrobial activity; however, it is able to permeabilize the LPS outer membrane. Our results demonstrate the antibiotic potentiator activity in the designed cWY6 peptide for several conventional antibiotics (vancomycin, rifampicin, erythromycin, novobiocin and azithromycin). Remarkably, the short cWY6 peptide exhibits wound-healing activity in in vitro assays. NMR, computational docking and biophysical studies describe the atomic-resolution structure of the peptide in complex with LPS and mode of action in disrupting the outer membrane. The dual activities of cWY6 peptide hold high promise for further translation to therapeutics. Published version S.B. acknowledges funding support from Singapore-MIT Alliance for Research and Technology (SMART) ING-000834 BIO IGN, Singapore.

Exosomes released into the extracellular matrix have been reported to contain metabolic biomarkers of various diseases. These intraluminal vesicles are typically found in blood, urine, saliva, breast milk, cerebrospinal fluid, semen, amniotic fluid, and ascites. Analysis of exosomal content with specific profiles of DNA, microRNA, proteins, and lipids can mirror their cellular origin and physiological state. Therefore, exosomal cargos may reflect the physiological processes at cellular level and can potentially be used as biomarkers. Herein, we report an optical detection method for assaying exosomal biomarkers that supersedes the state-of-the-art time consuming and laborious assays such as ELISA and NTA. The proposed assay monitors the changes in optical properties of poly(3-(4-methyl-3'-thienyloxy) propyltriethylammonium bromide) upon interacting with aptamers/peptide nucleic acids in the presence or absence of target biomarkers. As a proof of concept, this study demonstrates facile assaying of microRNA, DNA, and advanced glycation end products in exosomes isolated from human plasma with detection levels of ~1.2, 0.04, and 0.35 fM/exosome, respectively. Thus, the obtained results illustrate that the proposed methodology is applicable for rapid and facile detection of generic exosomal biomarkers for facilitating diseases diagnosis. Published version

Soil-water characteristic curve (SWCC) correlates the water content of a soil to its soil suction, which is a very important property of unsaturated soils. Osmotic tensiometers (OTs) have shown their capability in high soil suction measurement. This study tried to use OT combined with a pressure plate and WP4C dewpoint potentiometer to determine the SWCC of a residual soil. Three OTs with different measuring ranges (900 kPa, 1200 kPa, 2300 kPa) were prepared for soil suction measurement. The temperature effect on the pressure variations of OTs was illustrated based on Flory-Huggins polymer theories and an appropriate calibration equation was proposed to eliminate the temperature effect on the accuracy of soil suction measurement using OT. The OT showed a fast response in soil suction measurement and the equilibrium can be established in 10–15 min during SWCC measurement. Comparison of the SWCC data obtained from the pressure plate, OT, and WP4C dewpoint potentiometer proves that the OT had good performance in the determination of SWCC, especially for the transition zone (i.e., 10–1500 kPa suction range), by providing more data points to define the SWCC in a shorter period. The results show that the usage of OT will shorten the time required for the determination of SWCC and could be considered as a new and reliable technique in SWCC measurement. Submitted/Accepted version

Probiotics have been recognized as a bio-control measure in aquaculture against bacterial infections, especially with the surge of antibiotic-resistant pathogens. To fully exert the benefits of host-derived probiotics, which are well adapted to prevailing environmental conditions, microencapsulation is often needed to prevent them from gastric acidity, storage, and feed preparation processes before reaching the targeted sites and releasing in a desired manner. Common encapsulants include polysaccharides and proteins, immobilizing probiotics in a 3D matrix to maintain their viability and effectiveness. It is worth noticing that some of these encapsulants are seaweed-derived, which can be viable candidates as prebiotics when served as dietary supplements. Therefore, this work evaluated how four common polysaccharide encapsulants, alginate, carrageenan, xanthan, and gum arabic, can be utilized to modulate the host gut microbiota in an ex vivo model. Alginate and kappa-carrageenan were shortlisted for subsequent probiotic encapsulation based on their fermentability to produce short-chain fatty acids (SCFAs), which are energy sources for intestinal epithelial cells, and the bacterial composition change in the gut microflora after the co-incubation with the fish gut suspensions. Alginate is the most common encapsulant for probiotic encapsulation due to its ability to gel with di-valent ions to provide bacteria with good gastric protection and a lack of toxicity. Kappa-carrageenan can crosslink with mono-valent ions, and it produced the most abundant SCFAs and could not be selectively utilized by pathogenic bacteria. Both needle extrusion and spray drying were explored as encapsulation techniques. Extrusion is easy to set up and mild to bacteria. Extrusion parameters, including the needle size, the polysaccharide concentration, the flow rate, and the extrusion temperature, were optimized to yield microparticles with sufficient gastric protection. The survivability of the probiotics that underwent the simulated gastric fluid remained at the same 8 Log CFU/g magnitude as before the challenge, while no survival was found for naked bacteria. The robust protection of needle-extruded particles was accompanied by difficulty releasing bacteria in the intestine, with only around 5 Log CFU/g could be released in 2 hours. Considering fish’s short digestion time, needle extrusion may not be optimal for probiotic delivery in aquaculture. Spray drying was adopted to resolve the release problem. The host-derived strain can withstand the spray drying condition and readily release in the simulated intestinal fluid with uncompromised protection in the gastric environment. The ex vivo co-incubation study confirmed that introducing this encapsulated host-derived isolate could effectively suppress the growth of Aeromonas. Future work includes the in vivo challenge test in jade perch to assess whether manipulating the host gut microbiota through host-derived probiotic supplementation can increase disease resistance and how the bacteria persist in their native environment. Singapore National Biofilm Consortium

Information seeking and social support are integral to an individual’s social media use, during COVID-19 lockdowns these effects are exacerbated due to isolation. This study surveyed 756 Chinese individuals who experienced the second lockdown to discover how they utilized social media to combat stress. Findings showed that socioemotional coping and disengagement mediated relationships across social media use intensity and social media overload. Meanwhile, age moderated associations between coping strategies and an individual’s social media overload. Submitted/Accepted version

Understanding and mastering the structural evolution of water oxidation electrocatalysts lays the foundation to finetune their catalytic activity. Herein, we demonstrate that surface reconstruction of spinel oxides originates from the metal-oxygen covalency polarity in the MT-O-MO backbone. A stronger MO-O covalency relative to MT-O covalency is found beneficial for a more thorough reconstruction towards oxyhydroxides. The structure-reconstruction relationship allows precise prediction of the reconstruction ability of spinel pre-catalysts, based on which the reconstruction degree towards the in situ generated oxyhydroxides can be controlled. The investigations of oxyhydroxides generated from spinel pre-catalysts with the same reconstruction ability provide guidelines to navigate the cation selection in spinel pre-catalysts design. This work reveals the fundamentals for manipulating the surface reconstruction of spinel pre-catalysts for water oxidation. Ministry of Education (MOE) National Research Foundation (NRF) Published version This work was supported by Singapore Ministry of Education Tier 2 Grant (MOE-T2EP10220-0001) and the Singapore National Research Foundation under its Campus for Research Excellence And Technological Enterprise (CREATE) program.

Injury to the central nervous system (CNS) provokes an inflammatory reaction and secondary damage that result in further tissue damage and destruction of neurons away from the injury site. Upon injury, expression of connexin 43 (Cx43), a gap junction protein, upregulates and is responsible for the spread and amplification of cell death signals through these gap junctions. In this study, we hypothesise that the downregulation of Cx43 by scaffold-mediated controlled delivery of antisense oligodeoxynucleotide (asODN), would minimise secondary injuries and cell death, and thereby support tissue regeneration after nerve injuries. Specifically, using spinal cord injury (SCI) as a proof-of-principle, we utilised a fibre-hydrogel scaffold for sustained delivery of Cx43asODN, while providing synergistic topographical cues to guide axonal ingrowth. Correspondingly, scaffolds loaded with Cx43asODN, in the presence of NT-3, suppressed Cx43 up-regulation after complete transection SCI in rats. These scaffolds facilitated the sustained release of Cx43asODN for up to 25 days. Importantly, asODN treatment preserved neurons around the injury site, promoted axonal extension, decreased glial scarring, and reduced microglial activation after SCI. Our results suggest that implantation of such scaffold-mediated asODN delivery platform could serve as an effective alternative SCI therapeutic approach. Agency for Science, Technology and Research (A*STAR) Ministry of Education (MOE) Nanyang Technological University National Research Foundation (NRF) Skin Research Institute of Singapore (SRIS) Published version The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: The experiments in this work were supported by the Ministry of Education Tier 1 (RG38/19, RG37/20) and the National Research Foundation, Singapore, under its Intra-CREATE Thematic Grant (Award number: NRF2019-THE002-0001). We acknowledge the Agency for Science, Technology and Research (A*STAR) under its Industry Alignment Fund – Pre-Positioning Programme (IAF-PP) (Grant number H17/01/a0/0C9 and H1701a0004). We thank the Skin Research Institute of Singapore, Phase 2: SRIS@Novena for providing this work with the floor infrastructure and core equipment. JS Chin was also supported by IGS’s studentship.

Background: Researchers in the field of media now focus more on new media (e.g., social media, video games) than on traditional media, especially print media (e.g., books). However, for students, paper books remain an indispensable part of existence. Books are essential to the existence and education of adolescents. However, how do books affect their prosocial behavior? This study assessed the relationship between fiction reading, non-fiction reading, and prosocial behavior in Chinese adolescents (N = 631). Methods: In 2021, one junior and one senior secondary school in a middle-sized East Chinese city participated in this survey. We randomly chose participants from each grade at each school to cover all six grades, and the study included 631 adolescent. Results: Contrary to previous studies, we found that reading non-fiction is positively related to prosocial behavior through the mediation of social norm, and perspective-taking. In contrast, reading fiction was not significantly associated with social norm, perspective-taking, and prosocial behavior. Conclusions: The findings provide a novel comprehension of the effects of reading on prosocial behavior from the perspective of a different method and cultural context. This research provides valuable insights into the intervention of adolescents' prosocial behavior and book and reading policies. Submitted/Accepted version

Tracking interpersonal distances is essential for real-time social distancing management and ex-post contact tracing to prevent spreads of contagious diseases. Bluetooth neighbor discovery has been employed for such purposes in combating COVID-19, but does not provide satisfactory spatiotemporal resolutions. This paper presents ImmTrack, a system that uses a millimeter wave radar and exploits the inertial measurement data from user-carried smartphones or wearables to track interpersonal distances. By matching the movement traces reconstructed from the radar and inertial data, the pseudo identities of the inertial data can be transferred to the radar sensing results in the global coordinate system. The re-identified, radar-sensed movement trajectories are then used to track interpersonal distances. In a broader sense, ImmTrack is the first system that fuses data from millimeter wave radar and inertial measurement units for simultaneous user tracking and re-identification. Evaluation with up to 27 people in various indoor/outdoor environments shows ImmTrack's decimeters-seconds spatiotemporal accuracy in contact tracing, which is similar to that of the privacy-intrusive camera surveillance and significantly outperforms the Bluetooth neighbor discovery approach. Ministry of Education (MOE) Published version This research is supported in part by the Ministry of Education, Singapore, under its Academic Research Fund Tier 1 (RG88/22), in part by the Innovation and Technology Commission of Hong Kong under Grant No. GHP/126/19SZ, and in part by the Research Grants Council (RGC) of Hong Kong under Grant No. 14209619.

Parkinson's Disease (PD) is a prevalent neurodegenerative disorder that is characterized pathologically by the loss of A9-specific dopaminergic (DA) neurons in the substantia nigra pars compacta (SNpc) of the midbrain. Despite intensive research, the etiology of PD is currently unresolved, and the disease remains incurable. This, in part, is due to the lack of an experimental disease model that could faithfully recapitulate the features of human PD. However, the recent advent of induced pluripotent stem cell (iPSC) technology has allowed PD models to be created from patient-derived cells. Indeed, DA neurons from PD patients are now routinely established in many laboratories as monolayers as well as 3D organoid cultures that serve as useful toolboxes for understanding the mechanism underlying PD and also for drug discovery. At the same time, the iPSC technology also provides unprecedented opportunity for autologous cell-based therapy for the PD patient to be performed using the patient's own cells as starting materials. In this review, we provide an update on the molecular processes underpinning the development and differentiation of human pluripotent stem cells (PSCs) into midbrain DA neurons in both 2D and 3D cultures, as well as the latest advancements in using these cells for drug discovery and regenerative medicine. For the novice entering the field, the cornucopia of differentiation protocols reported for the generation of midbrain DA neurons may seem daunting. Here, we have distilled the essence of the different approaches and summarized the main factors driving DA neuronal differentiation, with the view to provide a useful guide to newcomers who are interested in developing iPSC-based models of PD. Ministry of Health (MOH) National Research Foundation (NRF) Published version This work was supported by grants from the Singapore National Research Foundation Competitive Research Program grant (NRF-CRP21-2018-0008) and the Singapore Ministry of Health Open Fund-Large Collaborative Grant (MOH-OFLCG18May-0002) awarded to K.L.L.

We report strong coupling between excitons and photonic bound states in the continuum in electrically-driven perovskite metatransistors. We show tunability of electroluminescence directivity by drain-source voltage and polarization control through metasurface design. Submitted/Accepted version

Existing studies have suggested that there may be a link between perception and production of speech sounds. In this paper we examine this link using data collected on Singapore English-Mandarin bilingual adults. We used a 2AFC task to measure perception of the Singapore Mandarin [tsʰuə́n]-[ʈʂʰuə́n] alveolar-retroflex contrast, and measured production using centre of gravity (CoG) measurements on speech recordings of alveolar and retroflex words. We found that a perception-production link may exist in our participants, with participants who exhibit less retroflexion in speech showing less sensitivity to retroflexion in ambiguous speech sounds. National Research Foundation (NRF)

Chalcogenide semiconductors offer excellent optoelectronic properties for their use in solar cells, exemplified by the commercialization of Cu(In,Ga)Se2- and CdTe-based photovoltaic technologies. Recently, several other chalcogenides have emerged as promising photoabsorbers for energy harvesting through the conversion of solar energy to electricity and fuels. The goal of this review is to summarize the development of emerging binary (Sb2X3, GeX, SnX), ternary (Cu2SnX3, Cu2GeX3, CuSbX2, AgBiX2), and quaternary (Cu2ZnSnX4, Ag2ZnSnX4, Cu2CdSnX4, Cu2ZnGeX4, Cu2BaSnX4) chalcogenides (X denotes S/Se), focusing especially on the comparative analysis of their optoelectronic performance metrics, electronic band structure, and point defect characteristics. The performance limiting factors of these photoabsorbers are discussed, together with suggestions for further improvement. Several relatively unexplored classes of chalcogenide compounds (such as chalcogenide perovskites, bichalcogenides, etc.) are highlighted, based on promising early reports on their optoelectronic properties. Finally, pathways for practical applications of emerging chalcogenides in solar energy harvesting are discussed against the backdrop of a market dominated by Si-based solar cells. National Research Foundation (NRF) L.W. and S.H. acknowledge the funding support from the CREATE Programme under the Campus for Research Excellence and Technological Enterprise (CREATE), which was supported by the National Research Foundation, Prime Minister's Office, Singapore. C.C. and J.T. acknowledge funding from the "National Natural Science Foundation of China", grant numbers 61725401 and 61904058. M.H. and S.C were supported by National Natural Science Foundation of China under grant Nos. 12174060 and 91833302, Shanghai Academic/Technology Research Leader (19XD1421300), the National Key Research and Development Program of China (2019YFE0118100), and Science Challenge Project (TZ2018004).

Evidence showing a strengthening of intense cold surge event (CSE) in East Asia, e.g. CSE of Jan 2016 and Jan–Feb 2008, is focusing attention towards the science of CSE onset prediction. Predicting the onset of such strong CSEs remains elusive as the extent of these surges varies over spatial and temporal scales. Changes in radiative cooling over Siberia in winter as potentially affected by changes in the Arctic are further expected to influence CSE occurrences in East Asia. Moreover, unprecedented and long lasting CSEs in East Asia have a very distinct Jet Stream pattern via their shifts from the climatological mean, influencing the lower troposphere. Here, using modelling framework we propose a new relationship between Jet Stream and Aleutian Low for identifying and characterizing atmospheric process that leads to CSEs in East Asia. Our results reveal new insight into the mechanisms of CSEs occurrences, the absence of which may lead to major constraints on reducing CSE onset prediction error.

In a cyber-physical system such as an autonomous vehicle (AV), machine learning (ML) models can be used to navigate and identify objects that may interfere with the vehicle's operation. However, ML models are unlikely to make accurate decisions when presented with data outside their training distribution. Out-of-distribution (OOD) detection can act as a safety monitor for ML models by identifying such samples at run time. However, in safety critical systems like AVs, OOD detection needs to satisfy real-time constraints in addition to functional requirements. In this demonstration, we use a mobile robot as a surrogate for an AV and use an OOD detector to identify potentially hazardous samples. The robot navigates a miniature town using image data and a YOLO object detection network. We show that our OOD detector is capable of identifying OOD images in real-time on an embedded platform concurrently performing object detection and lane following. We also show that it can be used to successfully stop the vehicle in the presence of unknown, novel samples., 3 pages, 5 figures, RTSS 2022

The interdependencies between the power distribution system (PDS) and water distribution system (WDS) are well-acknowledged in resilience analysis. Such interdependencies can hinder the post-disruption service restoration of both systems, and prolong the overall recovery process. Aimed at handling these issues, this paper proposes a resilience-oriented modeling and co-optimization method for coupled power and water (CPW) systems. The model integrates critical features of modern CPW systems, such as microgrids and distributed generations for power and water treatment plants, pumps, and tanks, for the water side. The interdependencies are extracted and formulated from mutual demand aspects. Further, a multiobjective optimization is presented to simultaneously reduce the loss of power load (LOPL) and loss of water load (LOWL). Finally, the method is tested on a coupled 33-bus power and 25-node water system and the result demonstrates the effectiveness of the proposed model and algorithm. Singapore-ETH Centre for Global Environmental Sustainability Submitted/Accepted version This work was supported by Future Resilient Systems, Singapore-ETH Centre through the National Research Foundation of Singapore under Its Campus for Research Excellence and Technological Enterprise program.

Tuning intermediate adsorption energy by shifting the d-band center offers a powerful strategy to tailor the reactivity of metal catalysts. Here we report a potential sweep method to grow Pd layer-by-layer on Au with the capability to in situ measure the surface structure through an ethanol oxidation reaction. Spectroscopic characterizations reveal charge-transfer induced valence band restructuring in the Pd overlayer, which shifts the d-band center away from the Fermi level compared to bulk Pd. Precise overlayer control gives the optimal bimetallic surface of two monolayers (ML) Pd on Au, which exhibits more than 370-fold mass activity enhancement in oxygen reduction reaction (at 0.9 V vs. reversible hydrogen electrode) and 40 mV increase in half-wave potential compared to the Pt/C. Tested in a homemade Zn-air battery, the 2-ML-Pd/Au/C exhibits a maximum power density of 296 mW/cm2 and specific activity of 804 mAh/gZn, much higher than Pt/C with the same catalyst loading amount. Agency for Science, Technology and Research (A*STAR) Ministry of Education (MOE) This work was supported by the fund from the Singapore Ministry of Education Academic Research Fund (AcRF) Tier 1: RG4/20 and Tier 2: MOET2EP10120-0002, and Agency for Science, Technology, and Research (A*Star IRG: A20E5c0080).

Carbene-based macromolecules are an emerging new stimuli-sensitive class of biomaterials that avoid the impediments of free radical polymerization but maintain a rapid liquid-to-biorubber transition. Activation of diazirine-grafted polycaprolactone polyol (CaproGlu) is limited to UVA wavelengths that have tissue exposure constraints and limited light intensities. For the first time, UVA is circumvented with visible light-emitting diodes at 445 nm (blue) to rapidly activate diazirine-to-carbene covalent cross-linking. Iridium photocatalysts serve to initiate diazirine, despite having little to no absorption at 445 nm. CaproGlu's liquid organic matrix dissolves the photocatalyst with no solvents required, creating a light transparent matrix. Considerable differences in cross-linking chemistry are observed in UVA vs visible/photocatalyst formulations. Empirical analysis and theoretical calculations reveal a more efficient conversion of diazirine directly to carbene with no diazoalkane intermediate detected. Photorheometry results demonstrate a correlation between shear moduli, joules light dose, and the lower limits of photocatalyst concentration required for the liquid-to-biorubber transition. Adhesion strength on ex vivo hydrated tissues exceeds that of cyanoacrylates, with a fixation strength of up to 20 kg·f·cm2. Preliminary toxicity assessment on leachates and materials directly in contact with mammalian fibroblast cells displays no signs of fibroblast cytotoxicity. Agency for Science, Technology and Research (A*STAR) Ministry of Education (MOE) Nanyang Technological University Accepted version T.W.J.S. and I.D. are co-inventors of patent application Hygroscopic, Crosslinking Coatings and Bioadhesives; PCT/ SG2018/050452. The project was supported by the Ministry of Education Tier 1 Grant RG17/18 (S): Novel light activated, diazo protecting groups; Ministry of Education Tier 2 Grant (MOE2018-T2-2-114): CaproGlu, double-sided wet tissue adhesives; NTUitive POC (Gap) Fund NGF/2018/05: Aesthetic Applications of CaproGlu Bioadhesives; and A*Star IAF PP Grant (H19/01/a0/0II9): CathoGlu Bioadhesives-preventing catheter extravasation and skin infections. L.B. acknowledges funding from the Spanish Ministry of Science and Innovation (MCIU), project PID2019- 104654GB-I00.

Grid-connected photovoltaic (PV) systems impose challenges like voltage fluctuations, low system inertia, and power quality issues. The need to tackle these challenges led to the introduction of flexible power point tracking (FPPT), where the PV power output is controlled by an energy management system, rather than solely operating the PV systems on the maximum power point. The requirement of fast transient response implies that algorithms such as the one proposed in this article are desirable. The proposed algorithm uses the secant method to achieve significantly improved results in comparison to the existing methods. The method also simplifies the prediction of variations during changes in the environment and power reference, hence, results in reduced oscillation around the set-point and faster convergence. Experimental validation is presented in this article for supporting the claims. The results in terms of accuracy, convergence rate, steady-state oscillations, and cumulative error are bench-marked against one of the most recent FPPT methods. Ministry of Education (MOE) Accepted version This work was supported by the Singapore Ministry of Education Academic Research Fund Tier 1 under Grant No: 2019-T1-001-168 (RG 80/19).

This paper presents a novel zero-sequence voltage injection method for discontinuous modulation (DM) in star-connected cascaded H-bridge (CHB) static compensators (StatComs). Conventional DM methods in CHB StatComs suffer from control interactions during unbalanced grid conditions. This paper proposes a DM that eliminates this control interaction by inserting a clamping transition within a third of the fundamental period. The transition instant is decided by comparing a duty cycle, which is calculated to mitigate the fundamental-frequency in the zero-sequence voltage for discontinuous operation, with a triangular carrier signal with a frequency of three times the fundamental. The clamping intervals under the proposed DM are affected by the phase-shift of this carrier. Specifically, the paper analyses the effects on the harmonic content of the proposed zero-sequence voltage, switching loss, twice-fundamental-frequency capacitor voltage ripple, and current total harmonic distortion, for different phase-shift angles of the DM carrier signal. Besides, the feasibility of the proposed DM in dealing with a grid voltage sag is also discussed. Nanyang Technological University National Research Foundation (NRF) Submitted/Accepted version This work was supported by the Office of Naval Research U.S. under DUNS Code: 595886219 and in part by the National Research Foundation of Singapore under “Distributed Energy Resource Management Systems (DERMS) For Energy Grid 2.0” project. The authors wish to acknowledge the Interdisciplinary Graduate Programme (IGP) at Nanyang Technological University for providing the conference funding support.