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New mesomorphic benzothiazol derivatives: Synthesis and characterization

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Chinese Chemical Letters 2013年第10期24卷 926-928页

作者： teck-ming koh Sie-Tiong Ha Guan-Yeow Yeap Hong-Cheu Lin Faculty of Engineering & Science Universiti Tunku Abdul RahmanJln Genting KlangSetapak Faculty of Science Universiti Tunku Abdul RahmanJln Universiti Centre for Biodiversity Research Universiti Tunku Abdul RahmanJln Universiti Liquid Crystal Research Laboratory School of Chemical SciencesUniversiti Sains Malaysia Department of Materials Science & Engineering National Chiao Tung University

In this paper, the synthesis of new mesomorphic benzothiazolyl derivatives, 6-ethoxy-2-[4-（4- alkyloxybenzoyloxy）benzylidenamino]benzothiazoles, is presented. The structures of the title compounds were elucidated using spectroscopic techniques, such as FT-IR, NMR （1H and 13C）, elemental analysis and El-MS. The mesomorphic behaviours of these compounds were determined by differential scanning calorimetric and polarizing optical microscopic techniques. Compounds exhibited nematic and tilted smectic phases upon heating from crystal phase. An obvious odd-even effect was observed in this homologous series.

关键词： Benzothiazole Nematic Smectic C Mesomorphic

Synthesis and mesomorphic evaluation of new calamitic liquid crystals containing benzothiazole core

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Chinese Chemical Letters 2011年第5期22卷 619-622页

作者： teck ming koh Sie Tiong Ha teck Leong Lee Siew Ling Lee Guan Yeow Yeap Hong Cheu Lin Ramesh T.Subramaniam Department of Science Faculty of Engineering & ScienceUniversiti Tunku Abdul RahmanJln Genting KlangSetapak53300 Kuala Lumpur.Malaysia Department of Chemistry National University of SingaporeSingapore 117543Singapore Department of Chemical Science Faculty of ScienceUniversiti Tunku Abdul RahmanJln UniversitiBandar Barat31900 KamparPerakMalaysia Ibnu Sina Institute for Fundamental Science Studies Universiti Teknologi Malaysia81310 UTM SkudaiJohorMalaysia Liquid Crystal Research Laboratory School of Chemical SciencesUniversiti Sains Malaysia11800 MindenPenangMalaysia Department of Materials Science & Engineering National Chiao Tung UniversityHsinchu 300Taiwan Center for Ionics University Malaya Department of Physics Faculty of ScienceUniversity of Malaya50603 Kuala LumpurMalaysia

The design and synthesis of new calamitic benzothiazole-based liquid crystals,2-[4-（4-alkyloxybenzoyloxy）-phenyl]ben-zothiazoles are *** target compound was characterized using spectroscopic techniques,such as FT-IR,NMR（~1H and ^（13）C）,microanalysis and *** liquid crystalline behaviours of these compounds were thoroughly examined by differential scanning calorimetry and polarizing optical microscope *** materials exhibited enantiotropic nematic phase with high thermal stability（168℃）.Smectic A phase starts to emerge as monotropic（metastable） phase from C10 member and changes into enantiotropic（stable） phase from C12 and persists up to C16 members.

关键词： Benzothiazole Alkoxy chain Nematic Smectic A Liquid crystal

Recent applications of macrocycles in supramolecular catalysis

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Chinese Chemical Letters 2024年第4期35卷 132-141页

作者： Conghui Wang Lei Xu Zhenhua Jia teck-Peng Loh College of Advanced Interdisciplinary Science and Technology Henan University of TechnologyZhengzhou 450001China Division of Chemistry and Biological Chemistry School of Chemistry Chemical Engineeringand BiotechnologyNanyang Technological UniversitySingapore 637371Singapore Institute of Advanced Synthesis School of Chemistry and Molecular Engineering Nanjing Tech UniversityNanjing 211816China

Numerous supramolecular macrocycles have been utilized for developing catalysts by exploiting their specific molecular recognition and ability to form inclusion complexes through noncovalent interactions. The cyclic structure and modified functional groups of these macrocycles can influence substrate and transition state stability, as well as reaction selectivity. The inner cavities of these macrocycles are particularly beneficial, as they enable substrates to adopt preorganized arrangements and serve as versatile platforms for highly efficient supramolecular catalytic systems. This minireview provides an overview of recent advancements in supramolecular catalysis using various macrocycles, such as crown ethers, cyclodextrins,calixarenes, pillararenes, cucurbiturils, and other novel macrocycles.

关键词： Supramolecular catalysis Macrocycle Host-guest interactions Confinement Selectivity

New mesogenic Schiff base esters comprising benzothiazole moiety:Synthesis and mesomorphic properties

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Chinese Chemical Letters 2009年第9期20卷 1081-1084页

作者： Sie Tiong Ha teck ming koh Guan Yeow Yeap Hong Cheu Lin Jun Kit Beh Yip Foo Win Peng Lim Boey Faculty of Engineering & Science Universiti Tunku Abdul RahmanJln Genting KlangSetapak 53300 Kuala LumpurMalaysia Liquid Crystal Research Laboratory School of Chemical SciencesUniversiti Sains Malaysia 11800 MindenPenangMalaysia Department of Materials Science & Engineering National Chiao Tung University1001 Ta-Hsueh RoadHsinchu 300Taiwan Faculty of Science Engineering & TechnologyUniversiti Tunku Abdul RahmanJln UniversitiBandar Barat 31900 KamparPerakMalaysia

A homologous series of Schiff base esters, 6-methoxy-2-（2-hydroxy-4-alkanoyloxybenzylidenamino）benzothiazoles, compris- ing a benzothiazole moiety as the core was synthesized. All the members of this series exhibited an enantiotropic nematic phase. The azomethine linkage along with the lateral hydroxyl and terminal methoxyl groups were found to exert an effect on the mesomorphic properties. 2009 Sie Tiong Ha. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.

关键词： Schiff bases Benzothiazoles Mesomorphic Nematic Structure-liquid crystal property relationship

Enhancing single-cell encapsulation in droplet microfluidics with fine-tunable on-chip sample enrichment

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Microsystems & Nanoengineering 2024年第1期10卷 149-160页

作者： Tao Tang Hao Zhao Shaofei Shen Like Yang Chwee teck Lim Department of Biomedical Engineering National University of Singapore117583 SingaporeSingapore Integrative Sciences and Engineering Programme NUS Graduate SchoolNational University of Singapore119077 SingaporeSingapore Shanxi Key Lab for Modernization of TCVM College of Life ScienceShanxi Agricultural UniversityTaiguShanxi 030801China Institute for Health Innovation&Technology National University of Singapore117599 SingaporeSingapore Mechanobiology Institute National University of Singapore117411 SingaporeSingapore Institute for Digital Molecular Analytics and Science Nanyang Technological University636921 SingaporeSingapore

Single-cell encapsulation in droplet microfluidics is commonly hindered by the tradeoff between cell suspension density and on-chip focusing *** this study,we introduce a novel droplet microfluidic chip to overcome this *** chip comprises a double spiral focusing unit,a flow resistance-based sample enrichment module with fine-tunable outlets,and a crossflow droplet generation *** a low-density cell/bead suspension(2×10^(6) objects/mL),cells/beads are focused into a near-equidistant linear arrangement within the double spiral *** excess water phase is diverted while cells/beads remain focused and sequentially encapsulated in individual *** performance was assessed through numerical simulations and experiments at three flow rates(40,60,80μL/min),demonstrating successful focusing at 40 and 80μL/min for beads and cells,*** addition,both simulation and experimental results revealed that the flow resistance at the sample enrichment module is adjustable by punching different outlets,allowing over 50%of the aqueous phase to be ***8n-based droplet detection algorithms realized the counting of cells/beads in droplets,statistically demonstrating single-cell and bead encapsulation rates of 72.2%and 79.2%,*** the results indicate that this on-chip sample enrichment approach can be further developed and employed as a critical component in single-cell encapsulation in water-in-oil droplets.

关键词： beads outlet sample

Synthesis and mesomorphic properties of new Schiff base esters with different alkyl chains

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Chinese Chemical Letters 2009年第7期20卷 767-770页

作者： Sie Tiong Ha Lay Khoon Ong Siew Teng Ong Guan Yeow Yeap Joanna Pik Wan Wong teck ming koh Hong Cheu Lin Faculty ofEngineering & Science Universiti Tunku Abdul RahmanJln Genting KlangSetapak 53300 Kuala LumpurMalaysia Faculty of Engineering & Science Universiti Tunku Abdul RahmanJln Genting KlangSetapak 53300 Kuala LumpurMalaysia Liquid Crystal Research Laboratory School of Chemical SciencesUniversiti Sains Malaysia 11800 MindenPenangMalaysia Department of Chemistry University of YorkHeslingtonYork YO10 5DDUnited Kingdom.

A new series of Schiff base esters, 4-（dimethylamino）benzylidene-4＇-alkanoyloxyanilines containing even number of carbons at the end group of the molecules （Cn-1H2n-1COO, n = 6, 8, 10, 12, 14, 16, 18） were synthesized. The present compounds were monotropic liquid crystals. It was also found that the end groups of the molecules had effect on the mesomorphic properties. C 2009 Sie Tiong Ha. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.

关键词： Liquid crystals Schiff base esters Monotropic compounds Mesomorphic properties

Mg/MgO interfaces as efficient hydrogen evolution cathodes causing accelerated corrosion of additive manufactured Mg alloys:A DFT analysis

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Journal of Magnesium and Alloys 2024年第1期12卷 110-119页

作者： Man-Fai Ng Kai Xiang Kuah teck Leong Tan Daniel John Blackwood Department of Materials Science&Engineering National University of Singapore9 Engineering Drive 1Singapore 117575Republic of Singapore Institute of High Performance Computing(IHPC) Agency for ScienceTechnology and Research(A∗STAR)1 Fusionopolis Way#16-16 ConnexisSingapore 138632Republic of Singapore

The corrosion rates of additive-manufactured Mg alloys are higher than their as-cast counterparts,possibly due to increased kinetics for the hydrogen evolution reaction on secondary phases,which may include oxide *** Kelvin Probe Force Microscopy demonstrated that MgO inclusions could act as cathodes for Mg corrosion,but their low conductivity likely precludes ***,the density of state calculations through density functional theory using hybrid HSE06 functional revealed overlapping electronic states at the Mg/MgO interface,which facilitates electron transfers and participates in redox *** determination of the hydrogen absorption energy at the Mg/MgO interface reveals it to be an excellent catalytic site,with HER being found to be a factor of 23x more efficient at the interface than on metallic *** results not only support the plausibility of the Mg/MgO interface being an effective cathode to the adjacent anodic Mg matrix during corrosion but also contribute to the understanding of the enhanced cathodic activities observed during the anodic dissolution of magnesium.

关键词： Magnesium Magnesium oxide Interface Hydrogen evolution DFT

Strategies for constructing seven-membered rings:Applications in natural product synthesis

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Chinese Chemical Letters 2024年第6期35卷 53-70页

作者： Peng Chen Lijuan Liang Yufei Zhu Zhimin Xing Zhenhua Jia teck-Peng Loh College of Advanced Interdisciplinary Science and Technology Henan University of TechnologyZhengzhou 450001China Division of Chemistry and Biological Chemistry School of Chemistry Chemical Engineeringand BiotechnologyNanyang Technological UniversitySingapore 637371Singapore Institute of Advanced Synthesis School of Chemistry and Molecular Engineering Nanjing Tech UniversityNanjing 211816China State Key Laboratory of Applied Organic Chemistry Department of ChemistryLanzhou UniversityLanzhou 730000China

The seven-membered ring motifs are found in bioactive pharmaceuticals and a wide range of natural products,including alkaloids and terpenoids,which hold significant importance in synthetic chemistry and has garnered considerable attention from both academia and *** the challenges faced in the past decade,the total synthesis of natural products incorporating the non-aromatic cycloheptane skeletons remains a compelling ***,numerous elegant strategies for constructing the sevenmembered ring system have been successfully *** review focuses on the recent advancements in this field from 2017 to April 2023,highlighting key transformations utilized to construct the non-aromatic cycloheptane core structures and serves as a valuable guide for synthetic chemists engaged in the total synthesis of natural products containing seven-membered ring motifs.

关键词： Seven-membered rings Total synthesis Natural products Synthetic strategy Cycloheptane

Proteomics techniques in protein biomarker discovery

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Quantitative Biology 2024年第1期12卷 53-69页

作者： Mahsa Babaei Soheila Kashanian Huang-teck Lee Frances Harding Department of Biology Faculty of ScienceRazi UniversityKermanshahIran Faculty of Chemistry Sensor and Biosensor Research Center(SBRC)Razi UniversityKermanshahIran Nanobiotechnology Department Faculty of Innovative Science and TechnologyRazi UniversityKermanshahIran Centre for Marine Bioproducts Development Flinders UniversityAdelaideSouth AustraliaAustralia Monash Institute of Pharmaceutical Sciences Monash UniversityMelbourneNew South WalesAustralia

Protein biomarkers represent specific biological activities and processes, so they have had a critical role in cancer diagnosis and medical care for more than 50 years. With the recent improvement in proteomics technologies, thousands of protein biomarker candidates have been developed for diverse disease states. Studies have used different types of samples for proteomics diagnosis. Samples were pretreated with appropriate techniques to increase the selectivity and sensitivity of the downstream analysis and purified to remove the contaminants. The purified samples were analyzed by several principal proteomics techniques to identify the specific protein. In this study, recent improvements in protein biomarker discovery, verification, and validation are investigated. Furthermore, the advantages, and disadvantages of conventional techniques, are discussed. Studies have used mass spectroscopy (MS) as a critical technique in the identification and quantification of candidate biomarkers. Nevertheless, after protein biomarker discovery, verification and validation have been required to reduce the false-positive rate where there have been higher number of samples. Multiple reaction monitoring (MRM), parallel reaction monitoring (PRM), and selected reaction monitoring (SRM), in combination with stable isotope-labeled internal standards, have been examined as options for biomarker verification, and enzyme-linked immunosorbent assay (ELISA) for validation.

关键词： biomarker discovery cancer biomarker gel-based methods gel-free methods mass spectroscopy proteomics