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Integrated Science Congress 2017

Integrated Science Congress 2017

Saturday, 18 November 2017 @ Special Programme in Science Headquarter, S16-03-02


Background
The Special Programme in Science (SPS, sps.nus.edu.sg) was established in 1996 as the Faculty of Science’s premiere academic programme to nurture aspirant scientists toward the growing R&D demands of the 21st-century knowledge-based economy. SPS achieves this through its unique multidisciplinary approach, peer-learning, literature as well as wet-lab research, and mentorship. This Integrated Science Congress culminates a 1.5-year long hardwork of SPS students, part of the holistic SPS Integrated Science Curriculum, which started at their very first day in the Programme, when they were introduced to scientific methodology and literature. Subsequently, they were experimenting on the very hypothesis they proposed, based on the literature review. And finally they are now ready to present their findings in this congress.


Programme

Time

Title of The Presentation

Note: click on the title to reveal the abstract and speakers

09:00 - 09:25

Electroreduction of CO2 to Syngas using Copper based Gas Diffusion Electrode

09:25 - 09:50

Simulating Gravitational Waves from Periodic Three-body Systems

09:50 - 10:15

Investigating the Role of Inverted Formin 1 in Cell Division and Migration

10:15 - 10:40

Analysis of Wntless (WLS) Expression in Synovial  Sarcoma & Its Relationship with Canonical Wnt Pathway

10:40 - 11:10

Tea Break

11:10 - 11:35

Investigation of the Mechanical Impact of Apoptotic Cell Extrusion in Epithelia

11:35 - 12:00

Investigating the Relationship between Bacterial Virulence and Antibiotic Resistance via Caenorhabditis elegans Killing Assay

12:00 - 12:25

Potential Alteration of Cellular Energetics by Galactose-1-Phosphate Accumulation in Classic Galactosaemia

12:25 - 12:50

Simulating Quantum Matrix Inversion as a Subroutine for Machine Learning

12:50 - 13:15

Fabrication and Microbial Characterisation of Nanostructured Film for Biomedical Applications

13:15 - 14:15

Lunch Break

14:15 - 14:40

Determining the Critical Active Site Residues for AaTI-plasmin Binding via Site-directed Mutagenesis

14:40 - 15:05

Enhancing the Stability and Photoluminescence of CsPbX3 (X= Br- and I-) Nanocrystals

15:05 - 15:30

Investigating the Effect of Glypican-1 Knockdown on the Morphology and Contraction of Bile Canaliculi

15:30 - 15:35

Closing Speech by Prof. Liou Yih-Cherng, Director of Special Programme In Science

15:35 - 15:40

Best Presentation and Best Poster Prize Giving Ceremony

Note: programme is subject to minor changes.


Acknowledgement

This congress is organized by the SPS head-mentors (Cheo Han Wen, Sharmalee Selvaraji, and Clement Tan Kok Yong), with the support from Dean’s Office, Faculty of Science. For more information about the Special Programme in Science, you may contact Andreas Dewanto (andreas.dewanto@sps.nus.edu.sg).


Abstracts and Speakers

Group #

Title, Presenters, and Abstract

1

Enhancing the Stability and Photoluminescence of CsPbX3 (X= Br- and I-) Nanocrystals

Speaker: Amelia Gunawan, Lau Shi Yun, Li Beiye

Supervisor: Tan Zhi Kuang


Abstract

Cesium lead halide perovskites (CsPbX3 where X = Cl, Br, I) nanocrystals (NCs) have excellent optoelectronic properties, facile solution processability, tunable band gap, and high photoluminescence (PL). Depending on the composition of halides, CsPbX3 NCs emit red, green, and blue PL that is ideal for application as LEDs. However, their commercialisation is greatly hampered by their spectral and PL instability. In this research, three critical findings that can not only enhance the stability, but improve the PL intensity of CsPbX3 NCs were established. Incorporation of organic additives, such as MPTMS and pyrrole, were found to have enhanced the PL intensity of green CsPbBr3 NCs effectively by a change factor of more than 1.05. Inorganic additive, ZnBr2, was also able to enhance the PL intensity of the NCs by a factor of 1.84 and was able to improve the NCs’ stability in addition. Moreover, factors that can enhance spectral stability of red mixed halide perovskite (CsPbBrI2) NCs for storage and usage purposes were discovered. It was found that by using non-polar cyclohexane as solvent and by minimising their exposure to light, CsPbBrI2 NCs will have greater spectral stability. These discoveries will help in the realisation of CsPbX3 NCs with long-term stability and high performance as efficient LEDs.


2

Fabrication and Microbial Characterisation of Nanostructured Film for Biomedical Applications


Speaker: Chow Lin Er, Chia Biing Hann, Lim Angel

Supervisor: Lee Yeong Yuh


Abstract

Bacterial infection on implanted medical devices has been a major and long-standing healthcare problem. Traditional approaches to combat these infections, including antibiotics and silver nanoparticles, face severe limitations that prevent them from being feasible solutions. This study investigates the use of nanostructured surfaces to reduce bacterial adhesion and proliferation. Drawing inspiration from biological nanostructured surfaces in nature with antibacterial properties, such as the wings of the Clanger Cicada, 75 nm, 500 nm, and 2 µm nanopillars were fabricated on poly-methyl-methacrylate (PMMA) and polycarbonate (PC) films using nanoimprint lithography. The effectiveness of these surface nanostructures to reduce the bacterial surface coverage of a common strain of Staphylococcus aureus bacteria was investigated. S. aureus were incubated on the films in a mini-chamber setup, and the bacterial surface coverage after 2 hours was quantified using fluorescence microscopy. Preliminary results indicate that both 75 nm and 2 µm pillar structures consistently exhibit significant reduction in bacterial surface coverage on both PMMA and PC substrate. Investigation of 500 nm nanopores revealed that, unlike the nanopillars, 500 nm nanopores exhibited no significant antibacterial activity against S. aureus. Investigation on the correlation between surface hydrophobicity and bacterial surface coverage showed that the trends were not consistent across nanostructures. These results suggest that bacterial adhesion and proliferation are not only governed by hydrophobicity, but also by other factors such as the presence of nanostructures and the surface energy of the substrate. This study demonstrated the capabilities of 75 nm and 2 µm pillar structures to reduce bacterial surface coverage of S. aureus, and their potential to be imprinted on the surfaces of packaging material for implanted medical devices to reduce infection.


3

Simulating Gravitational Waves from Periodic Three-body Systems


Speaker: Neville Chen Jia Pern, Bianca Lee Yanxi

Supervisor: Kenneth Hong Chong Ming


Abstract

Gravitational waves are disturbances in spacetime due to a changing mass distribution. The waves encode information about the source in them, which can be extracted by studying the characteristics of the waves. The advanced Laser Interferometry Gravitational Waves Observatory (LIGO) accomplished the feat of identifying the masses composing binary sources and their orbital motion from the waves. We emulate the work of LIGO by studying the gravitational waves from periodic three-body systems and matching the wave properties to the source. Three-body systems are common and are comparatively less studied in the context of gravitational wave astronomy. In this paper, we explore the waveforms of periodic three-body systems and compare the waves to those of a binary star. We find that the waveforms di.er greatly in shape compared to the binary star when the three bodies do not orbit in a circular motion about their centre-of-mass. However, no apparent pattern can be deduced about the orbit from the shape of the waves. In contrast, the ratio between the gravitational wave period and orbital period is indicative of the symmetry of the mass distribution. Thus, it may aid in the deduction of the relative positions of the three bodies at specifi.c instances of the orbit.


4

Simulating Quantum Matrix Inversion as a Subroutine for Machine Learning


Speaker: Quek Zhi Hao, Kim Mu Young

Supervisor: Joseph Fitzsimons


Abstract

Quantum Computing has garnered attention in recent years by o.ffering methods to solve certain computational problems that outperform best-known classical algorithms. At the same time, linear equation solving often, of which Machine Learning constitutes a use case, features computational problems with high-dimension datasets, i.e. datasets that are well-suited to exploit quantum speedups. In this report, we present the Quantum Matrix Inversion algorithm as a build up to the quantum analogue of the common classical Machine Learning algorithm known as the Support Vector Machine. We also present several subroutines such as the Hamiltonian Simulation and Phase Estimation algorithms, as well as their respective schematics. We simulate the training stage of the Quantum Support Vector Machine algorithm and its subroutines on a classical computer and verify their operation for a 2x2 matrix, achieving a simulated .fidelity of over 99.8% in the case where the decomposition of the desired kernel matrix closely matches our simulated precision. We further simulate the inversion of a 4x4 matrix. Finally, we discuss some limitations of our simulations and possible constraints of using these algorithms on an actual quantum computer.


5

Investigating the Relationship between Bacterial Virulence and Antibiotic Resistance via Caenorhabditis elegans Killing Assay


Speaker: Thor Wei Jie, Johanan Dravium Ponniah

Supervisor: Gan Yunn Hwen


Abstract

Antibiotic resistance poses a grave challenge to public health, hence there is a need to find out what factors are affected by antibiotic resistance. Virulence, which is defined as the ability of a pathogen to cause disease, has been found to be related to antibiotic resistance. However, the relationship between antibiotic resistance and virulence remains unclear. This project aims to establish that relationship by determining the virulence of different strains of Acinetobacter baumanii with different antibiotic resistances against Caenorhabditis elegans as the model organism. There was no trend to be found based on the results from the challenge of C. elegans with different A. baumanii strains. This could be due to the complex nature of antibiotic resistance and hence, further testing is required.


6

Electroreduction of CO2 to Syngas using Copper based Gas Diffusion Electrode


Speaker: Lau Rachel, Lim Zhen Jia

Supervisor: Jason Yeo Boon Siang


Abstract

The electroreduction of CO2 can be a viable alternative to the use of fossil fuel in producing chemical feedstock such as synthesis gas (syngas). Syngas, a mixture of H2 and CO, is used to synthesize a variety of long chain hydrocarbons via the Fisher-Tropsch (FT) reaction. However, the ratio of H2/CO is catalyst-dependent. In this work, we attempt to reduce CO2 to syngas with adjustable H2/CO ratios for industrial use. We adopted the gas diffusion electrode in our electrochemical cell to overcome mass transport limitation of CO2 in conventional cell and achieve high current. Copper was selected as the electrocatalyst due to its selectivity for CO, earth-abundance and low cost. We deposited the catalyst nanoparticles on carbon gas diffusion electrodes using air-brushing method. The product distribution was investigated and we found that CO and formate were the main carbon products. H2/CO ratio was also observed to vary as we alter the potential applied. We achieved the production of syngas with a desirable H2/CO ratio of 1.96 at −1.1 V (vs. RHE). This gas composition is an ideal feedstock for cobalt-catalyzed FT synthesis.


7

Investigation of the Mechanical Impact of Apoptotic Cell Extrusion in Epithelia


Speaker: Deborah Fong Yuhui, Lang Si Min, Tuieng Ren Jie

Supervisor: Yusuke Toyama


Abstract

The epithelial barrier remains impermeable to invading pathogens despite high rates of turnover. To prevent a gap left by the dying cell, the monolayer removes the apoptotic cell via apoptotic cell extrusion, a mechanical process intricately coordinated by neighbouring cells. Despite well-studied mechanisms of apoptotic cell extrusion via lamellipodia cell crawling and actomyosin ring contraction, the mechanical tension within the neighbouring cells facilitating the extrusion process is poorly understood. This study aims to elucidate this tension by studying traction forces exerted by lamellipodia, as well as the localisation of a well-known mechanosensing protein, Yes-associated protein (YAP), as an indicator of the tension. Here, ultraviolet laser was used to induce apoptosis, traction force microscopy was used to quantify traction forces exerted by neighbouring cells, and time-lapse images of YAP tagged to green fluorescent protein were obtained via live confocal imaging. This study has combined analyses from the mechanical forces during apoptosis and the biochemical response from YAP, correlating them on a temporal scale. Results show that during apoptotic cell extrusion, there is an outward radial propagation of traction forces as well as YAP translocation into the nucleus. From the observations, it is proposed that neighbouring cells experience an increase in tension in the process of apoptotic cell extrusion, directing the localisation of YAP into the nucleus.


8

Investigating the Effect of Glypican-1 Knockdown on the Morphology and Contraction of Bile Canaliculi


Speaker: Christopher Martinus, Nusrat Jahan, Zhou Jie Fu

Supervisor: Hanry Yu


Abstract

In our body, bile normally flows from the bile canaliculi found between hepatocytes to the intrahepatic bile duct then to the extrahepatic bile duct before it is delivered to the duodenum. Biliary atresia is the obstruction of this bile flow, believed to be caused by a blockage in the biliary network. Through Genome Wide Association Study (GWAS), glypican-1 (Gpc1) was identified to be associated to biliary atresia. Furthermore, the poor prognosis of treatments targeted towards the common bile ducts suggests that the bile canaliculi may be involved in contributing to biliary atresia. We hypothesize that knockdown of Gpc1 will affect bile canalicular contraction and morphology. In order to investigate this, we compared the bile canaliculi morphology and contraction cycle in control and Gpc1 knockdown rat hepatocytes by live imaging. We have observed that there is less bile canaliculi contraction in the Gpc1 knockdown samples compared to the control, and the morphology was also significantly altered. Our results suggests that  reduced Gpc1 expression may be correlated to a reduction in bile flow through reduced bile canaliculi contraction, although the exact mechanism that led to the observation remains to be investigated.


9

Analysis of Wntless (WLS) Expression in Synovial  Sarcoma & Its Relationship with Canonical Wnt Pathway


Speaker: Jessie Wong Ling Ai, Sabrina Chua Yah Tse, Tan Li Yang

Supervisor: Susan Hue Swee Shan


Abstract

Wnt pathway is an extensively featured signalling pathway that is known for its role in embryonic development and tissue homeostasis. Dysregulation of this pathway is well established in oncogenesis. Synovial sarcoma (SS) is a rare form of soft tissue cancer that is known to have a poor response to chemotherapeutic treatments. Recent studies have implicated the role of constitutively active canonical Wnt signalling in SS tumourigenesis. Although the activation of canonical Wnt pathway has been investigated in SS, the role of Wntless (WLS), a protein found upstream of Wnt pathway affecting both canonical and non-canonical Wnt ligands, has not been well explored. In this study, we evaluated the protein expression of WLS in SS by immunohistochemistry (IHC) on a tissue microarray (TMA) block consisting of SS patient samples. We found that WLS is over-expressed in the majority of our SS samples. Given that WLS presents as an attractive target to modulate activated Wnt signalling, the current study paves the path for future studies in elucidating the role of this upstream core component of Wnt signalling pathway in providing a novel therapeutic strategy for SS treatment.


10

Determining the Critical Active Site Residues for AaTI-plasmin Binding via Site-directed Mutagenesis


Speaker: Hoh Kar Ling, Zhao Tianzhi

Supervisor: Henry Mok Yu-Keung


Abstract

Blood-sucking invertebrates ingest blood for nutritional purpose. To fight against viral or microbial infection that occurs in the blood-feeding process, organisms like mosquitoes develop defensive mechanisms, which involve serine protease inhibitors such as the Kazal inhibitors. In this study, such a Kazal inhibitor, AaTI found in Aedes aegypti, is investigated to identify the amino acid(s) within its reactive site loop that is essential for its inhibition activity. Mutant proteins were generated by site-directed mutagenesis according to decisions made based on the multiple sequence alignment (MSA) of AaTI and its homologous inhibitors, Infestin 1, Infestin 4, Leech-Derived Tryptase Inhibitor (LDTI) and Rhodniin. Wild type and mutant proteins were expressed, purified and characterized. The evaluation of MSA, circular dichroism spectroscopy and activity assay shows that P4’ position is the most essential among P2, P2’, P3’, and P4’ positions, as this mutation leads to complete function loss. We also speculated that P2’ and P4’ residues are acting together for normal plasmin inhibition. Moreover, the P2 and P3’ residues are also contributing to the efficiency of AaTI-plasmin binding.


11

Investigating the Role of Inverted Formin 1 in Cell Division and Migration


Speaker: Lee Ann Gie, Nicole Ong Wen Pei, Ravinraj S/O Ramaraj

Supervisor: Wu Min


Abstract

Cell division and migration are important cellular process which involve both the microtubule and actin networks. Inverted Formin 1 (INF1) is a unique formin that contains both the formin homology 1 and 2 domains and a unique microtubule-binding domain, allowing it to associate with both the actin and microtubule networks. INF1 has also been found to be necessary for Golgi apparatus assembly, whose role as a microtubule-organising centre suggests a link between INF1, microtubules and the Golgi apparatus. We thus investigated the role of INF1 in cell division and cell migration to determine its effect on the microtubule network. Significant reductions in cell division ability of shINF1 cells were observed, along with morphological defects and significantly reduced motility. The rescue of INF1 function with full-length human INF1 partially recovered cell morphology regulation, though it failed to recover cell division or motility phenotypes. In addition, there was no significant difference observed for cell division duration in shINF1 cells, suggesting that INF1’s role is more prevalent prior to the M-phase of the cell cycle. The differences in morphology, migration velocity and persistence in migration suggest hinderances of the Golgi-derived microtubule network, thus reducing focal adhesion turnover, protrusion formation and polarity establishment in shINF1 cells. These differences observed from a knockdown of INF1 provide new insight into the role of this unique formin in regulating the microtubule network, in addition to its well-known activity with actin.


12

Potential Alteration of Cellular Energetics by Galactose-1-Phosphate Accumulation in Classic Galactosaemia


Speaker: Cheng Li Yi, Oh Sher Li, Tricia Wong Po Yee

Supervisor: Thilo Hagen


Abstract

Classic Galactosaemia (CG) is a genetic disease characterised by the inability of patients to express galactose-1-phosphate uridyltransferase (GALT), and therefore are unable to metabolise galactose. GALT-deficient patients have shown long-term toxicity syndromes, despite implementing a galactose-restricted diet. Multiple sources have established the presence of Galactose 1-Phosphate (Gal-1P) accumulation in GALT-deficient cells. However, the association between Gal-1P accumulation and cellular toxicity is not well established. In this paper, we studied the mechanism of Gal-1P production by galactokinase (GALK) and the interaction between metabolites in the Leloir and glycolytic pathways. In particular, GALK2 demonstrated a lack of product inhibition by Gal-1P. This absence of product inhibition could be the reason for accumulation of Gal-1P, which was observed to reach a 103-fold increase in HEK293T cells during the metabolomics study. Concurrently, glucose assays on cell cultures, containing both glucose and galactose, revealed that glucose uptake was not affected by presence of galactose. Despite the availability of both glucose and galactose, the majority of ATP production in cells was likely attributed to glucose rather than galactose due to inefficient Gal-1P metabolism. Furthermore, analysis of metabolite levels suggested an association between Gal-1P accumulation and inhibition of the glycolytic pathway. Results of this study therefore affirmed Gal-1P accumulation in the presence of galactose, and its association with changes in cellular metabolism that could eventually explain toxicity in CG patients.



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Live Curious. Be Challenged.


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