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Chemistry

2019

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Articles 1861 - 1890 of 1908

Full-Text Articles in Physical Sciences and Mathematics

ผลของตัวเร่งปฏิกิริยาต่อคุณภาพของน้ำมันชีวภาพจากไพโรไลซิสชิ้นไม้ยูคาลิปตัสและซังข้าวโพดในเครื่องปฏิกรณ์เบดนิ่ง, วรเวช ศรีปราโมช Jan 2019

ผลของตัวเร่งปฏิกิริยาต่อคุณภาพของน้ำมันชีวภาพจากไพโรไลซิสชิ้นไม้ยูคาลิปตัสและซังข้าวโพดในเครื่องปฏิกรณ์เบดนิ่ง, วรเวช ศรีปราโมช

Chulalongkorn University Theses and Dissertations (Chula ETD)

งานวิจัยนี้ศึกษาภาวะที่เหมาะสมสำหรับการไพโรไลซิสไม้ยูคาลิปตัสและซังข้าวโพดในเครื่องปฏิกรณ์แบบเบดนิ่ง พบว่าภาวะที่เหมาะสมสำหรับชีวมวลทั้งสองชนิดคือ เวลาทำปฏิกิริยาที่ 30 นาที อุณหภูมิ 500 องศาเซลเซียส และขนาดอนุภาคของชีวมวลระหว่าง 0.50-0.71 มิลลิเมตร ส่วนอัตราการไหลแก๊สไนโตรเจนสำหรับไม้ยูคาลิปตัสคือ 120 มิลลิลิตรต่อนาที และสำหรับ ซังข้าวโพดคือ 80 มิลลิลิตรต่อนาที ให้ผลได้น้ำมันชีวภาพสูงสุดของไม้ยูคาลิปตัสและซังข้าวโพดที่ร้อยละ 31.69 และ 22.01 โดยน้ำหนัก ตามลำดับ โดยน้ำมันชีวภาพจากชีวมวลทั้งสองชนิดให้ค่าความร้อนสูงขึ้นและใกล้เคียงกันคือ 23.14 และ 23.27 เมกะจูล/กิโลกรัม ตามลำดับ สอดคล้องกับอัตราส่วน H/C และ O/C ของน้ำมันชีวภาพจากชีวมวลทั้งสองชนิดที่มีค่าต่ำกว่าในชีวมวล เมื่อวิเคราะห์องค์ประกอบของน้ำมันชีวภาพพบว่าส่วนใหญ่เป็นสารในกลุ่มฟีนอล รองลงมาคือสารในกลุ่มกรดคาร์บอกซิลิก แอลดีไฮด์ อีเทอร์ คีโทน ไฮโดรคาร์บอน แซ็กคาไรด์ และสารที่มีปริมาณน้อยสุดคือสารในกลุ่มฟูแรน และจากการศึกษาผลของตัวเร่งปฏิกิริยาโดโลไมต์และเอฟซีซีใช้แล้ว พบว่าปริมาณตัวเร่งปฏิกิริยาที่เหมาะสมสำหรับชีวมวลทั้งสองชนิดคือร้อยละ 5 โดยน้ำหนัก และตัวเร่งปฏิกิริยาทั้งสองชนิดไม่มีผลอย่างมีนัยสำคัญต่อการลดออกซิเจนในน้ำมันชีวภาพ

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สมบัติของพอลิแล็กทิกแอซิดเติมด้วยเซลลูโลส-กราฟต์-พอลิสไตรีน, วิมาลา กรินทร์ไตรทิพย์ Jan 2019

สมบัติของพอลิแล็กทิกแอซิดเติมด้วยเซลลูโลส-กราฟต์-พอลิสไตรีน, วิมาลา กรินทร์ไตรทิพย์

Chulalongkorn University Theses and Dissertations (Chula ETD)

งานวิจัยนี้มีวัตถุประสงค์เพื่อเตรียมและศึกษาสมบัติของพอลิแล็กทิกแอซิดผสมด้วยเซลลูโลส-กราฟต์-พอลิสไตรีน โดยสังเคราะห์เซลลูโลส-กราฟต์-พอลิสไตรีนด้วยวิธีแบบอิมัลชันพอลิเมอไรเซชัน การดัดแปรพื้นผิวของเซลลูโลสสามารถยืนยันได้จากการทดสอบเอกลักษณ์ด้วยเทคนิคเทคนิคอินฟราเรดสเปกโตรสโกปี และความเสถียรภาพทางความร้อนด้วยเทคนิควิเคราะห์น้ำหนักภายใต้ความร้อน (ทีจีเอ) จากนั้นนำไปผสมกับพอลิแล็กทิกแอซิดด้วยเครื่องอัดรีดสกรูคู่ ที่ร้อยละ 1 3 5 และ 10 โดยมวล นำคอมพอสิตที่ได้ขึ้นรูปเพื่อศึกษาสมบัติเชิงกล สัณฐานวิทยา ความร้อน การย่อยสลาย และการดูดซึมน้ำ จากการศึกษาพบว่าการเติมเซลลูโลส-กราฟต์-พอลิสไตรีนมีผลต่อความทนแรงกระแทก ความทนแรง ยังส์มอดุลัส และการยืด ณ จุดขาดเพิ่มขึ้น โดยการเติมเซลลูโลส-กราฟต์-พอลิสไตรีนที่ร้อยละ 3 โดยมวล ให้ค่าความทนแรงกระแทกของคอมพอสิตสูงสุด แต่ค่าการยืด ณ จุดขาดลดลง เมื่อนำมาศึกษาสมบัติทางความร้อนของคอมพอสิต พบว่า ความเสถียรทางความร้อนของพอลิเมอร์ผสมมีค่าเพิ่มขึ้นเมื่อเปรียบเทียบกับพอลิแล็กทิกแอซิดบริสุทธิ์ สำหรับสมบัติการย่อยสลายด้วยวิธีการฝังกลบ และสมบัติการดูดซึมน้ำ พบว่า ปริมาณของเซลลูโลส-กราฟต์-พอลิสไตรีนที่เพิ่มขึ้น ส่งผลให้ร้อยละน้ำหนักที่หายไปของวัสดุคอมพอสิตเมื่อถูกฝังกลบเพิ่มขึ้น และดูดซึมน้ำได้มากขึ้นเมื่อถูกแช่ในน้ำที่อุณหภูมิห้อง ตามลำดับ

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การเตรียมคาร์บอกซีเมทิลเซลลูโลส/พอลิไวนิลแอลกอฮอล์/นาโนไททาเนียมไดออกไซด์ไฮโดรเจลสำหรับการประยุกต์ตกแต่งแผลที่มีสมบัติต้านแบคทีเรีย, วัชรพล ขำช้าง Jan 2019

การเตรียมคาร์บอกซีเมทิลเซลลูโลส/พอลิไวนิลแอลกอฮอล์/นาโนไททาเนียมไดออกไซด์ไฮโดรเจลสำหรับการประยุกต์ตกแต่งแผลที่มีสมบัติต้านแบคทีเรีย, วัชรพล ขำช้าง

Chulalongkorn University Theses and Dissertations (Chula ETD)

งานวิจัยนี้ทำการเตรียมคาร์บอกซีเมทิลเซลลูโลส/พอลิไวนิลแอลกอฮอล์/นาโนไททาเนียมไดออกไซด์ไฮโดรเจลฟิล์มโดยใช้กรดซิตริกเป็นสารเชื่อมขวางสำหรับการประยุกต์ใช้เป็นวัสดุตกแต่งแผลจากนั้นทำการพิสูจน์เอกลักษณ์ดังนี้คือ การวิเคราะห์หมู่ฟังก์ชันโดยเทคนิค ATR-FTIR การวิเคราะห์ลักษณะสัณฐานวิทยาที่พื้นผิวโดยกล้องจุลทรรศน์อิเล็คตรอนแบบส่องกราด การทดสอบสมบัติการทนต่อแรงดึง การวิเคราะห์พฤติกรรมในการบวมตัว สัดส่วนการเกิดเจล ความสามารถในการกักเก็บยา ร้อยละการกักเก็บยา พฤติกรรมในการปลดปล่อยยา การต้านแบคทีเรียโดยวิเคราะห์จากร้อยละการลดลงของแบคทีเรีย โดยจากการพิสูจน์เอกลักษณ์พบว่า การเพิ่มขึ้นขององค์ประกอบพอลิไวนิลแอลกอฮอล์ในฟิล์มทำให้ได้ฟิล์มที่มีสัดส่วนในการเกิดเจลที่เพิ่มขึ้นเมื่อเปรียบเทียบฟิล์มที่ปริมาณกรดซิตริกเท่ากันในทางตรงกันข้ามพบว่าเมื่อเพิ่มปริมาณองค์ประกอบพอลิไวนิลแอลกอฮอล์ในฟิล์มทำให้ค่าสัดส่วนการบวมตัวของฟิล์มมีค่าที่น้อยลงเพราะว่าการเพิ่มปริมาณองค์ประกอบพอลิไวนิลแอลกอฮอล์ในฟิล์มทำให้เพิ่มระดับการเชื่อมขวางของฟิล์มจึงทำให้มีสัดส่วนการเกิดเจลที่เพิ่มขึ้นต่อมาจากเทคนิค ATR-FTIR ได้ยืนยันการเกิดการเชื่อมขวางระหว่างโมเลกุลคาร์บอกซีเมทิลเซลลูโลสกับพอลิไวนิลแอลกอฮอล์โดยพันธะเอสเทอร์และสำหรับการทดสอบการทนต่อแรงดึงพบว่าค่าความคงทนต่อแรงดึง ค่าความเหนียว ค่าร้อยละการยืดตัว ณ จุดขาด ของฟิล์มมีค่าลดลงตามปริมาณการเพิ่มขึ้นขององค์ประกอบพอลิไวนิลแอลกอฮอล์ในการทดสอบฟิล์มแห้งต่อมาสำหรับการศึกษาพฤติกรรมในการกักเก็บยาของฟิล์มพบว่าฟิล์มทุกสูตรมีพฤติกรรมในการกักเก็บยาที่คล้ายคลึงกันและการศึกษาพฤติกรรมในการปลดปล่อยยาพบว่าฟิล์มทั้งหมดสามารถช่วยชะลอการปลดปล่อยยาเททราไซคลินให้ช้าลงได้สุดท้ายจากการทดสอบความสามารถในการต้านแบคทีเรียจากฟิล์มสูตร CMC 80/PVA 20/TiO2 2% พบว่าฟิล์มมีสมบัติต้านแบคทีเรียทั้งแกรมบวก (S. aureus) และ แกรมลบ (E.coli) โดยให้ค่าร้อยละการลดลงของแบคทีเรียเท่ากับ 100 เมื่อทดสอบตามมาตรฐาน JIS Z 2801 โดยสรุปจากข้อมูลผลการทดลองทั้งหมดทำให้สรุปได้ว่าไฮโดรเจลฟิล์มมีประสิทธิภาพที่เพียงพอในการนำไปประยุกต์ใช้เป็นวัสดุตกแต่งแผล

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Development Of An In-Field Method For The Detection Of Barium In Various Water Samples Using Differential Pulse Anodic Stripping Voltammetry, Samantha Ridgway, Magdalena Wajrak Jan 2019

Development Of An In-Field Method For The Detection Of Barium In Various Water Samples Using Differential Pulse Anodic Stripping Voltammetry, Samantha Ridgway, Magdalena Wajrak

Research outputs 2014 to 2021

This work presents a reliable, cost-effective, rapid and in-field voltammetric method for the detection of barium. The optimized method consists of an ultrathin mercury film deposited in situ on a glassy carbon electrode in dilute potassium chloride without deoxygenation, using differential pulse anodic stripping voltammetry (DP-ASV). Application of the method allowed for the quantitative determination of barium concentration in a variety of waters and brake pad dust samples. Comparative analysis of sample results from DP-ASV with inductively coupled plasma mass spectroscopy (ICP-MS) showed a mean percent difference of 1.8%.

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Molecular Dynamics Simulation Of Phenolic Compound Adsorption On Amine-Functionalized Carbon Nanotubes, Nutapong Tanatananon Jan 2019

Molecular Dynamics Simulation Of Phenolic Compound Adsorption On Amine-Functionalized Carbon Nanotubes, Nutapong Tanatananon

Chulalongkorn University Theses and Dissertations (Chula ETD)

The interactions between green tea phenolic compounds, including (−)-epigallocatechin gallate (EGCG) and (−)-epigallocatechin (EGC), and various amine groups functionalized on carbon nanotube (CNT) were studied by all-atom molecular dynamics (MD) simulations. The amine functional groups: ethylenediamine (EDA), triethylenetetramine (TETA), and melamine (MA) were considered in this study. Simulated results showed that amine molecular structure grafted on CNT surface affected diffusion and adsorption of EGCG and EGC. The EDA-functionalized CNT (EDA/CNT) provided a strong adsorption affinity to EGCG and EGC with their bicyclic segments located within the EDA layer. It is because the functionalized-EDA structure was well-defined and given empty site …

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Correlation Of Restitution Coefficient : Experiment And Computational Fluid Dynamics Simulation, Tarabordin Yurata Jan 2019

Correlation Of Restitution Coefficient : Experiment And Computational Fluid Dynamics Simulation, Tarabordin Yurata

Chulalongkorn University Theses and Dissertations (Chula ETD)

The computational fluid dynamics with the discrete element method (CFD-DEM) is widely used to predict the hydrodynamics profile of the multiphase flow of fluid-solid or fluidization process. The coefficient of restitution (COR) is one of the most important parameters which is vital for CFD-DEM simulation. This parameter denotes the ratio of the relative velocity after the collision to the relative velocity before the collision. The appropriate value of the coefficient of restitution must receive attention to obtain the realistic collision and hydrodynamics profile. However, this parameter is still selected by trial and error in traditional CFD-DEM due to the lacking …

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Metallophthalocyanine-Based Electrode For Sodium-Ion Batteries, Apinut Chongphanitkul Jan 2019

Metallophthalocyanine-Based Electrode For Sodium-Ion Batteries, Apinut Chongphanitkul

Chulalongkorn University Theses and Dissertations (Chula ETD)

In this study, metallophthalocyanine-modified electrodes were fabricated and investigated for their electrochemical properties and energy storage performance. Six kinds of electrodes were prepared from indium tin oxide-coated glass (ITO-coated glass) substrates coated with titanium dioxide nanotube (TNT), poly(3,4-ethylenedioxythiophene) (PEDOT) and reduced graphene oxide (rGO) to improve conductivity of the substrates and surface area for the phthalocyanine-based materials. Target phthalocyanine monomers possess amino groups and Co(II) or Ni(II) central metals. On surface of each electrodes, films of the monomers were coated by a drop-casting technique, while those of their polymers were formed by electropolymerization. According to study on electrochemically active surface …

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Non-Hessian Method For Normal Coordinates Calculation, Chirayut Supunyabut Jan 2019

Non-Hessian Method For Normal Coordinates Calculation, Chirayut Supunyabut

Chulalongkorn University Theses and Dissertations (Chula ETD)

Normal mode analysis (NMA) plays an essential role in chemistry for a very long time. It is both a key to understanding molecular motions, especially vibration motions, and to identifying characteristic peaks in infrared and Raman spectra. The traditional NMA requires the construction of a Hessian matrix and using harmonic approximation, which is almost impossible when large molecules and quantum mechanics are involved. Usually, NMA serves a complete set of normal coordinates that describes all possible motion modes of a molecule. This work presents a novel methodology to calculate normal coordinates that use only molecular geometries as input by considering …

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Interactions Of Pyrrolidinyl Peptide Nucleic Acid With Oligodeoxyguanosine And Biosensing Applications, Chayan Charoenpakdee Jan 2019

Interactions Of Pyrrolidinyl Peptide Nucleic Acid With Oligodeoxyguanosine And Biosensing Applications, Chayan Charoenpakdee

Chulalongkorn University Theses and Dissertations (Chula ETD)

Pyrrolidinyl peptide nucleic acid is a DNA mimic consisting of proline-2-aminocyclopentane carboxylic acid (acpcPNA) as a core structure. It binds to DNA to form a more stable hybrid while showing greater selectivity and affinity than the conventional DNA and PNA probes. In this study, we aim to develop novel DNA sensing systems based on the acpcPNA probe. In the first part, graphene oxide (GO) was used as an external quencher which could effectively quench the fluorescein-labeled PNA probe. A remarkable fluorescence restoration was achieved after the addition of a complementary DNA target. This acpcPNA-GO combination was successfully used to monitor …

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Chemical Constituents Of Knema Angustifolia Stem And Biological Activities, Dung Le Thi Kim Jan 2019

Chemical Constituents Of Knema Angustifolia Stem And Biological Activities, Dung Le Thi Kim

Chulalongkorn University Theses and Dissertations (Chula ETD)

The medicinal plant Knema angustifolia has been used in Thai folk medicine for the treatment of various diseases, especially related to body tonic or blood tonic agent. Chemical data on this plant are scarce. A novel para-benzoquinone, angustiquinone (3), along with ten known compounds, rapanone (1), embelin (2), quercetin (4), kaempferol (5), bergenin (6), 11-O-acetyl bergenin (7), catechin (8), isovanillic acid (9), protocatechuic acid (10) and gallic acid (11) were isolated from the n-hexane and EtOAc extracts of the stems of K. angustifolia. Their structures were unambiguously elucidated using extensive 1D and 2D NMR analyses, high-resolution mass spectrometry along with …

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Water Dispersible Α-Mangostin By Self-Assembly Process, Jutamad Bumrung Jan 2019

Water Dispersible Α-Mangostin By Self-Assembly Process, Jutamad Bumrung

Chulalongkorn University Theses and Dissertations (Chula ETD)

α-Mangostin, major bioactive compounds in Garcinia mangostana Linn, displays various interesting biological activities. However, the poor water solubility of α-mangostin has limited its use in the cosmetics and pharmaceutics. Here, we solve α-mangostin's solubility by creating water dispersible α-mangostin particles through self-assembly process with no need of any auxiliary agents such as polymers or surfactants. The simple and upscalable process gives 100% pure α-mangostin spherical particles with nanometer sizes. FT-IR result suggests that intermolecular interaction among α-mangostin molecules in the nanoparticles is weaker than that of the original α-mangostin solid. The lower thermal stability of the particles as compared to …

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Development Of Sensing Platforms Using Bulk Optode Technique For Detection Of Silver And Mercury Ions, Manoon Phichi Jan 2019

Development Of Sensing Platforms Using Bulk Optode Technique For Detection Of Silver And Mercury Ions, Manoon Phichi

Chulalongkorn University Theses and Dissertations (Chula ETD)

This research described new analytical devices for Ag+ and Hg2+ detection using bulk optode technique. The optode containing 25,27-di(benzothiazolyl)-26,28-hydroxycalix[4]arene (CU1) as an ion-selective ionophore, chromoionophore XIV as a lipophilic pH indicator, and KTpClPB as an ion-exchanger was prepared and used as a sensing agent in the proposed devices. The optode sensors responded to Ag+ and Hg2+ by changing the color from blue to yellow. The colorimetric-based detection was carried out by using the proposed paper-based analytical device. A simple fabrication method was performed by simply dropping the cocktail onto the filter paper, and the detection method was easily performed by …

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Bioactive Compounds From Lichen Usnea Baileyi (Stirt.) Zahlbr. And Usnic Acid Derivatives, Kieu Van Nguyen Jan 2019

Bioactive Compounds From Lichen Usnea Baileyi (Stirt.) Zahlbr. And Usnic Acid Derivatives, Kieu Van Nguyen

Chulalongkorn University Theses and Dissertations (Chula ETD)

The investigation of chemical constituents of lichen Usnea baileyi (Stirt.) Zahlbr. led to the isolation of ten new bisxanthones (US1−3, 5-11) and a new depsidone (US4). The structures were unambiguously established by the spectroscopic evidence including HRESIMS, 1D and 2D NMR, as well as comparison to literature data. Moreover, the absolute configurations were elucidated through ECD analyses, DFT-NMR calculations and subsequent DP4 probability score. The biological activities of isolated bisxanthones were evaluated for antiparasitic, cytotoxic (US1-3), antibacterial, and enzymatic inhibitory (tyrosinase and α-glucosidase) (US5-11) activities. The results revealed null to mild bioactivities against Plasmodium falciparum (antiparasitic activity) as well as …

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Development Of Biosensor Using Pyrrolidinyl Pna For Screening Of Hepatitis C Virus Dna, Narathorn Nisab Jan 2019

Development Of Biosensor Using Pyrrolidinyl Pna For Screening Of Hepatitis C Virus Dna, Narathorn Nisab

Chulalongkorn University Theses and Dissertations (Chula ETD)

In this work, a new paper-based analytical device (PAD) that relied on fluorescence measurement was developed for label-free detection of hepatitis C virus (HCV) DNA. Pyrrolidinyl peptide nucleic acid (acpcPNA) was covalently modified onto the patterned cellulose paper to act as a specific probe for capturing the HCV DNA target according to Watson−Crick base-paring rules. The single-stranded (ssDNA)-specific dye which can be electrostatically attached to the surface-bound DNA was employed as the signaling element for the fluorescence-based detection via a smartphone gadget and an iOS application. To acquire the optimal sensitivity, several experimental parameters, namely acpcPNA probe concentration, hybridization time, …

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Preparation Of Calcium Citrate Based Vitamin B₁₂/Cisplatin Nanocomposite As Novel Targeted Drug Carrier, Natchanon Rimsueb Jan 2019

Preparation Of Calcium Citrate Based Vitamin B₁₂/Cisplatin Nanocomposite As Novel Targeted Drug Carrier, Natchanon Rimsueb

Chulalongkorn University Theses and Dissertations (Chula ETD)

The synthesis of calcium citrate-cisplatin composite nanoparticles (CaCit@CDDP) was prepared via simple chemical co-precipitation method. Carboxyl group on the surface of calcium citrate nanoparticle was successfully modified with vitamin B12 (B12). The spherical nanoparticles were observed by Scanning Electron Microscope. The obtained size was 553.0±65.0 nm. The percentage of CDDP and B12 in the nanoparticles were analysed by Thermogravimetric Analysis and Inductively Coupled Plasma Optical Emission Spectroscopy. The interior of the nanoparticles was studied by Raman spectroscopy. Moreover, the Prestoblue viability assay showed that CaCit@CDDP-B12 significantly decreased 60% of cell viability of A549 cancer cell line in comparison to the …

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Structure And Dynamics Of Spin Label Side Chains In Membrane Protein Using Molecular Dynamics Simulations, Ngoc-Lan Le-Nguyen Jan 2019

Structure And Dynamics Of Spin Label Side Chains In Membrane Protein Using Molecular Dynamics Simulations, Ngoc-Lan Le-Nguyen

Chulalongkorn University Theses and Dissertations (Chula ETD)

Site-directed spin labeling (SDSL) combined with electron paramagnetic resonance (EPR) spectroscopy is a powerful approach to explore the structure and dynamics of biological complex systems. Nitroxide spin label is the most widely used probe for SDSL in the study of structure and function of biomolecules. However, the behavior of the nitroxide spin label is not well understood. This study aims to characterize the structural and dynamical properties of the spin label in the voltage-sensing domain (VSD) of KvAP, a potassium channel from the thermophilic archaea Aeropyrum pernix by mean of molecular dynamics (MD) studies. MD simulations for unlabeled and a …

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Chemical Constituents From The Stems Of Garcinia Cylindrocarpa And The Stem Bark Of Garcinia Picrorhiza And Garcinia Tetrandra, Edwin Risky Sukandar Jan 2019

Chemical Constituents From The Stems Of Garcinia Cylindrocarpa And The Stem Bark Of Garcinia Picrorhiza And Garcinia Tetrandra, Edwin Risky Sukandar

Chulalongkorn University Theses and Dissertations (Chula ETD)

Aiming to discover novel bioactive secondary metabolites from genus Garcinia, we performed phytochemical and biological investigations of three Garcinia species collected from Indonesia. A series of chromatographic techniques and spectroscopic data analysis were used to isolate and characterize the Garcinia phytochemicals. The cytotoxicity of the isolated compounds was evaluated against five human cancer cell lines (HeLa S3, Hep G2, HT-29, MCF-7, and KB) using MTT assay. Four new xanthones, cylindroxanthones D–G, and two new biphenyls, cylindrobiphenyls A and B, together with 28 known compounds were successfully isolated from G. cylindrocarpa stems. From the stem bark of G. tetrandra, nine new …

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Structure And Hydration Property Of Low Molecular Weight Hyaluronic Acid By Molecular Dynamics Simulations, Panyakorn Taweechat Jan 2019

Structure And Hydration Property Of Low Molecular Weight Hyaluronic Acid By Molecular Dynamics Simulations, Panyakorn Taweechat

Chulalongkorn University Theses and Dissertations (Chula ETD)

Hyaluronic acid (HA) is a biopolymer of disaccharide with two alternate glycosidic bonds, β(1,3) and β(1,4). It has a wide-range of applications in medicine, nutrition and cosmetics. A molecular dynamics (MD) study in aqueous condition presented here unveiled conformational variability in association with the flexibility of the glycosidic linkers, which depends on the number of disaccharide units. HA chain maintains a rigid rod-like conformation with short chain lengths i.e. with 1 to 10 disaccharide units. Crossover from a rod-like to a random-coil conformation is observed with increasing the chain length i.e. with 20-50 disaccharide units. MD and DFT calculations demonstrated …

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Detection Of Nitrite By Thread-Based And Paper-Based Devices By Modified Griess Reagent, Pitcha Singhaphan Jan 2019

Detection Of Nitrite By Thread-Based And Paper-Based Devices By Modified Griess Reagent, Pitcha Singhaphan

Chulalongkorn University Theses and Dissertations (Chula ETD)

New thread-based and paper-based devices for the determination of nitrite ions based on modified Griess reagent were developed. The surface of the materials was chemically modified with p-aminobenzoyl moiety and chromotropic acid was used as a coupling reagent. The functionalization of the materials was confirmed by Raman spectroscopy. By using the thread-based device, the detection of nitrite was achieved by measuring the color band length. The optimum concentration of chromotropic acid was 5 mM in 0.10 M sulfuric acid mixed with 0.2 M citric acid. The working range was from 50 to 1,000 µM with a sample volume of 15 …

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Detection Of Cyanide Ions Using Chemosensing Ensembles Under Indicator Displacement Assays, Ratanakorn Teerasarunyanon Jan 2019

Detection Of Cyanide Ions Using Chemosensing Ensembles Under Indicator Displacement Assays, Ratanakorn Teerasarunyanon

Chulalongkorn University Theses and Dissertations (Chula ETD)

Anion recognition is an attractive area of research in recent decades as anions play an important role in a wide range of chemical, biological, and environmental processes. This dissertation reports three projects dedicated to anion recognition with applications in fluoride and cyanide sensing. The first project of the dissertation describes the chemistry of two novel anthracene derivatives bearing one and two dimesitylboryl substituents (compounds 1 and 2, respectively) for the complexation of anions. All investigations provide insights into the electronic structure and effect of fluoride and cyanide binding. The results demonstrate that these boranes have a high affinity for fluoride …

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Determination Of Perchlorate And Thiocyanate Ions By Ion-Selective Membrane And Bulk Optode Techniques Using Experimental Design Approach, Supacha Wirojsaengthong Jan 2019

Determination Of Perchlorate And Thiocyanate Ions By Ion-Selective Membrane And Bulk Optode Techniques Using Experimental Design Approach, Supacha Wirojsaengthong

Chulalongkorn University Theses and Dissertations (Chula ETD)

This research aimed to develop the detection method for perchlorate and thiocyanate in aqueous solutions using potentiometric and colorimetric techniques. The optimum conditions were designed by the central composite design (CCD) with response surface methodology (RSM). The potentiometric response of perchlorate‒selective electrode using di‒tripodal amine calix[4]arene copper(II) complex (L1-Cu) in PVC membrane was studied. The optimized pH, ion exchanger and ionophore concentrations were found at pH 8.0, 3.25 mmol/kg and 13.25 mmol/kg, respectively. The optimized condition performed a Nernstian slope of –58.02 mV/decade with R2=0.9994 in a working concentration range of 1.00×10‒6 – 1.00×10‒2 M, and the detection limit was …

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Optimization Of Enantiomeric Separation By Gas Chromatography Using Beta-Cyclodextrin Derivatives As Stationary Phases, Suchada Muangsri Jan 2019

Optimization Of Enantiomeric Separation By Gas Chromatography Using Beta-Cyclodextrin Derivatives As Stationary Phases, Suchada Muangsri

Chulalongkorn University Theses and Dissertations (Chula ETD)

Enantiomeric separations of seventy-two underivatized chiral alcohols and forty-three trifluoroacetyl derivatives of chiral amines of various structures were investigated by gas chromatography using two types of cyclodextrin-based chiral stationary phases: heptakis(2,3-di-O-acetyl-6-O-tert-butyldimethylsilyl)-beta-CD (or BSiAc) and heptakis(2,3-di-O-methyl-6-O-tert-butyldimethylsilyl)-beta-CD (or BSiMe). Each compound was analyzed by temperature program and the optimum isothermal condition for each compound was also determined. It was found that resolution and elution temperature obtained from a temperature program run could be used as a guideline for quickly determining the optimum isothermal condition for enantiomeric separation. For a 15-meter long capillary column, if a resolution less than 1.0 was obtained, a …

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Development Of Fluorinated Rhodacyanine Analogues For Anti-Leishmaniasis, Thitiya Lasing Jan 2019

Development Of Fluorinated Rhodacyanine Analogues For Anti-Leishmaniasis, Thitiya Lasing

Chulalongkorn University Theses and Dissertations (Chula ETD)

Recently, fluorinated rhodacyanine has been disclosed as a highly effective agent against Leishmania donovani; it was shown that replacement of hydrogen with a fluorine atom on a benzothiazole unit significantly enhanced the anti-leishmanial activity. However, the role of the fluorine substituent in this analogue has not yet been clarified and mechanism of actions remains unclear. In this research, fifteen novel and three known fluorine-containing rhodacyanine analogues (10c, and 11a-11q) were synthesized and tested the anti-leishmanial activity against promastigote and axenic amastigote stages of L. martiniquensis and L. orientalis, the indigenous Leishmania species of Thailand. The SAR knowledge of this series …

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Synthesis Of Coumarins As Carbonic Anhydrase Ii And Α-Glucosidase Inhibitors, Truc Phan Thi Hong Jan 2019

Synthesis Of Coumarins As Carbonic Anhydrase Ii And Α-Glucosidase Inhibitors, Truc Phan Thi Hong

Chulalongkorn University Theses and Dissertations (Chula ETD)

Coumarins have been occupied an important position in medicinal chemistry. In this research, umbelliferone derivatives were evaluated for inhibitory activity of two enzymes, namely carbonic anhydrase II (CA II) and α-glucosidase. First, ether, brominated ether and ester derivatives of umbelliferone were synthesized, characterized and tested for CA II inhibitory activity. However, the inhibition data could not be used to make the exact conclusion about structure-activity relationship owing to their unrepeatable results. For the second part, thirty-four derivatives of umbelliferone (ether, brominated ether, ester, sulfonamide and sulfonate derivatives) were synthesized and explored for anti-α-glucosidase activity. It was disclosed that anti-α-glucosidase activity …

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Polyvinyl Alcohol/Starch Modified Cotton Thread For Glucose Distance-Based Colorimetric Detection, Pornchanok Punnoy Jan 2019

Polyvinyl Alcohol/Starch Modified Cotton Thread For Glucose Distance-Based Colorimetric Detection, Pornchanok Punnoy

Chulalongkorn University Theses and Dissertations (Chula ETD)

In this thesis, polyvinyl alcohol (PVA) and starch modified cotton thread was developed as a cotton thread-based device for distance-based colorimetric detection of hydrogen peroxide (H2O2) and glucose. PVA and starch, the biocompatible polymers, were modified on a cotton thread to enhance the enzymatic stability and reagent immobilization efficiency. The colorimetric glucose detection of the device was based on a bienzymatic reaction involving glucose oxidase (GOx) and horseradish peroxidase (HRP), incorporated with potassium iodide (KI) as an indicator, which was oxidized by H2O2 to provide blue-black color band of an iodine–starch complex. The length of color band on the cotton …

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Effects Of Synthetic Glyceryl Ester Additives On Cold Flow Properties Of Diesel Oil, Ruchapong Kaweewut Jan 2019

Effects Of Synthetic Glyceryl Ester Additives On Cold Flow Properties Of Diesel Oil, Ruchapong Kaweewut

Chulalongkorn University Theses and Dissertations (Chula ETD)

The synthesis of solketal derivatives with some selected fatty acid (stearic acid, palmitic acid, lauric acid, myristic acid, oleic acid and linolenic acid) to glyceryl esters was conducted. All compounds were characterized by spectroscopic means. Cold flow properties of diesel oil with these glyceryl ester additives were studied in terms of pour point (PP). Glyceryl laurate was the most effective pour point decreasing at 1,000 mg/kg (DPP = 3°C). However, the blended diesel of 1,000 mg/kg glyceryl laurate could not commercialize finishing product because that was hazy diesel at room temperature. The combination of glyceryl laurate and commercial additive was …

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Preparation Of Starch-Filled Polyisocyanurate Foams Catalyzed By Zinc-Ammonia Complex/Potassium Octoate, Sirima Goonack Jan 2019

Preparation Of Starch-Filled Polyisocyanurate Foams Catalyzed By Zinc-Ammonia Complex/Potassium Octoate, Sirima Goonack

Chulalongkorn University Theses and Dissertations (Chula ETD)

The research aimed to reduce apparent density and improve fire resistance of polyisocyanurate (PIR) foam. PIR foams were prepared using zinc-ammonia complex and potassium octoate as catalyst for gelling/blowing and trimerization reactions, respectively. Three types of starch produced in Thailand, namely glutinous rice flour, rice flour and mung bean starch, were used as additives for PIR foams. The characterized properties of PIR foams modified with starches are reaction times (cream time, gel time, rise time and tack free time), polyisocyanurate/polyurethane (PIR/PUR) ratio, %isocyanate conversion, apparent density, compressive property, morphology and fire behavior. These properties are compared with PIR foam without …

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Magnetic Nanoparticles Stabilized By Phosphorylcholine-Containing Polymer For Antibody Free C-Reactive Protein Detection, Suttawan Saipia Jan 2019

Magnetic Nanoparticles Stabilized By Phosphorylcholine-Containing Polymer For Antibody Free C-Reactive Protein Detection, Suttawan Saipia

Chulalongkorn University Theses and Dissertations (Chula ETD)

This research aims to develop a simple, yet effective assay for C-reactive protein (CRP) detection based on a combination of magnetic separation and antibody-free colorimetric assay. Magnetic nanoparticles stabilized with phosphorylcholine-containing polymer, poly[methacrylic acid)-ran-(methacryloyloxyethyl phosphorylcholine)] (PMAMPC-MNPs) were prepared by co-precipitation of ferric and ferrous salts in the presence of PMAMPC. Carboxyl groups in the methacrylic acid (MA) repeat units chelate with Fe atoms during MNPs formation while the methacryloyloxyethyl phosphorylcholine (MPC) repeat units provide specifically binding sites and conjugate with CRP in presence of Ca2+. The PMAMPC-MNPs were characterized by ATR-FTIR, TEM, DLS, TGA and XRD. To determine the CRP …

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Developing A Basket-Shaped Host Molecule Based On P-Tert-Butylcalix[4]Arene Featuring Urea Groups For Encapsulating Volatile Guest Molecules, Lokugama Widanelage Vidula Priyadarshana Jan 2019

Developing A Basket-Shaped Host Molecule Based On P-Tert-Butylcalix[4]Arene Featuring Urea Groups For Encapsulating Volatile Guest Molecules, Lokugama Widanelage Vidula Priyadarshana

Masters Theses

Molecular baskets are a group of synthetic host molecules which are designed to govern the inclusion of small guest molecules. The basic structural features of basket-shaped host molecules are a cavity for holding a much smaller guest molecule and tunable gates for keeping the guest molecule inside. These types of gates can be tuned by changing temperature, concentration, pH, etc. In this research group's previous study, a molecular basket of cal ix[ 4]arene with carboxylic acid groups was synthesized by functionalizing calix[4]arene's phenol hydroxyl groups with benzyl bromide building blocks. In the study detailed here, 1 , l '-((5-(bromomethyl)-1,3-phenylene)bis(methylene))bis(3-isopropylurea) was …

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Solvation Properites Of Supercritical Carbon Dioxide Using Chirped-Pulse Fourier-Transform Microwave Spectra Of Carbon Dioxide / 1, 1-Difluoroethene (Dfe) Mixtures, Tulana Ariyaratne Subasinghe Arachchige Jan 2019

Solvation Properites Of Supercritical Carbon Dioxide Using Chirped-Pulse Fourier-Transform Microwave Spectra Of Carbon Dioxide / 1, 1-Difluoroethene (Dfe) Mixtures, Tulana Ariyaratne Subasinghe Arachchige

Masters Theses

Supercritical carbon dioxide (sc-C02) is a highly utilized industrial substance identified as an excellent solvent and a surfactant, which is cheaper and less hazardous than other typical solvents. The higher solubility of fluorinated hydrocarbons than their hydrocarbon (HC) analogs is not well understood and the theory behind the microsolvation of sc-C02 cannot be fully explained with the existing chemical information. Microwave spectroscopy is a good method of identifying the structural arrangement of clusters made from fluorinated HCs and C02. I n this project, microwave scans of the four different mixtures of 1 , 1-difluoroethene (DFE) …

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