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2017

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Dynamic Model To Predict Ac Critical Flashover Voltage Of Nonuniformly Polluted Insulators Under Thermal Ionization Conditions, Saeed Shahabi, Ahmad Gholami Jan 2017

Dynamic Model To Predict Ac Critical Flashover Voltage Of Nonuniformly Polluted Insulators Under Thermal Ionization Conditions, Saeed Shahabi, Ahmad Gholami

Turkish Journal of Electrical Engineering and Computer Sciences

This paper presents a theoretical dynamic model based on the Hampton criterion and Mayr's equation for predicting the critical values of flashover on the surface of nonuniformly polluted cap and pin porcelain insulators. The nonuniform pollution layer on the surface of the insulator, the number of disk insulator units, and the geometry of the insulator such as diameter and ribs are the important factors used for prediction. Two types of pollution layer configuration, linear and graded, are introduced as nonuniform pollution layers. The influences of the nonuniform pollution layer on critical flashover voltage are investigated. Furthermore, a random value is …

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Automatic Reduction Of Periodic Noise In Images Using Adaptive Gaussian Star Filter, Seni̇ha Ketenci̇, Ali̇ Gangal Jan 2017

Automatic Reduction Of Periodic Noise In Images Using Adaptive Gaussian Star Filter, Seni̇ha Ketenci̇, Ali̇ Gangal

Turkish Journal of Electrical Engineering and Computer Sciences

The reduction of noise in images is a crucial issue and an inevitable preprocessing step in image analysis. Many diverse noise sources, which disrupt source images, exist in nature and through manmade devices. Periodic noise is one such disruption that has a periodic pattern in the spatial domain, causing hills in the image spectrum. In practice, quasiperiodic noise is commonly encountered instead of periodic noise. It has a more complex frequency spectrum, such as a star shape, in place of a pure delta shape in the frequency amplitude spectrum. In this study, we consider designing a star shape Gaussian filter …

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Design And Realization Of A Novel Planar Array Antenna And Low Power Lna For Ku-Band Small Satellite Communications, Lida Kouhalvandi, Osman Ceylan, Selçuk Paker, Hasan Bülent Yağci Jan 2017

Design And Realization Of A Novel Planar Array Antenna And Low Power Lna For Ku-Band Small Satellite Communications, Lida Kouhalvandi, Osman Ceylan, Selçuk Paker, Hasan Bülent Yağci

Turkish Journal of Electrical Engineering and Computer Sciences

This article presents both a four-element novel microstrip array antenna and a low noise amplifier (LNA) for a Ku-band small satellite receiver. It includes all design details with measurement results of the fabricated array antenna and LNA. Measured minimum and maximum gains of the proposed antenna are 10.1 and 10.9 dBi in 11.9-12.9 GHz band frequency. The designed LNA has a noise figure lower than 1.5 dB and gain higher than 8 dB (at 2 V, 10 mA biasing). In order to reduce the design period and cost, discrete components are chosen and a hetero-junction FET is used as the …

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Threshold Distance-Based Cluster Routing Protocols For Static And Mobile Wireless Sensor Networks, Padmavati Khandnor, Trilok Aseri Jan 2017

Threshold Distance-Based Cluster Routing Protocols For Static And Mobile Wireless Sensor Networks, Padmavati Khandnor, Trilok Aseri

Turkish Journal of Electrical Engineering and Computer Sciences

In cluster-based wireless sensor network routing protocols, when the cluster head transfers data based on single hop transmission to the sink node, then the cluster heads that are farther away deplete more energy as compared to nearby cluster heads. This condenses load balancing in the network. If the cluster heads collaborate with each other and transfer data based on multihop transmission, then the cluster heads nearer to the sink node are burdened with significant relay traffic and deplete energy much faster, which causes a network coverage problem also known as a hot spot problem. To avoid both of the above …

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Optimal Determination Of Island Boundaries Besides The Optimal Placement Of D-Statcom Devices And Dg Units, Sadeq Rabie, Hossein Afrakhte Jan 2017

Optimal Determination Of Island Boundaries Besides The Optimal Placement Of D-Statcom Devices And Dg Units, Sadeq Rabie, Hossein Afrakhte

Turkish Journal of Electrical Engineering and Computer Sciences

In this study, integration of three important concepts of distributed generation, D-FACTS devices, and microgrids are evaluated. The performance of a microgrid is dependent on its location, capacity, and placement of DG units and D-FACTS devices. In this paper a new method is proposed to simultaneously determine the optimal number, location, and capacity of DG units and D-STATCOM devices and optimal boundaries of electrical islands in the independent mode of microgrids. The main objective is to minimize the economic costs. The optimal locations of DG units and D-STATCOM devices should be determined to maximize the DG capacities with minimum loss …

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Design And Implementation Of A Modified Communication Disturbance Observer For Teleoperation Systems, Zahra Zeinaly, Amin Ramezani, Sadjaad Ozgoli Jan 2017

Design And Implementation Of A Modified Communication Disturbance Observer For Teleoperation Systems, Zahra Zeinaly, Amin Ramezani, Sadjaad Ozgoli

Turkish Journal of Electrical Engineering and Computer Sciences

In this paper, a novel structure for a communication disturbance observer in teleoperation systems is proposed to achieve robust stability. A time delay compensation method based on the concept of network disturbance and a communication disturbance observer (CDOB) has been proposed in past research. Unlike model-based approaches, it works without a time delay model. Therefore, it can be implemented in teleoperation systems with unknown and time-varying delay. However, it has been observed that the system model errors and external disturbances seriously affect the steady-state characteristics. Hence, in this paper, to achieve robustness against disturbance and model uncertainty, the structure of …

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Communications Protocol For Power Management In Smart Homes, Milan Bjelica, Mirjana Simic Pejovic Jan 2017

Communications Protocol For Power Management In Smart Homes, Milan Bjelica, Mirjana Simic Pejovic

Turkish Journal of Electrical Engineering and Computer Sciences

Emergency situations, incentives for energy efficiency, new pricing plans, and distributed electricity market jointly require home automation systems that would conform an instantaneous load to a dynamically set limit. In this paper, a novel machine-to-machine communications protocol that interconnects a smart grid and smart house is described. ''Intelligent'' domestic appliances use it to coordinate their switch-on times so that the assigned power quota will not be exceeded. In this way, the end-user experience can be improved by reducing the electricity bills, conveniently conforming to prepaid pricing plans, or even by providing continued service at possibly reduced consumption levels during power …

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Investigation Of Secondary Cooling Design Enhancements In Thermally Limited Compact Notebooks, Muhammad Azhar Ali Khan, Eray Uzgören, Ali̇ Muhtaroğlu Jan 2017

Investigation Of Secondary Cooling Design Enhancements In Thermally Limited Compact Notebooks, Muhammad Azhar Ali Khan, Eray Uzgören, Ali̇ Muhtaroğlu

Turkish Journal of Electrical Engineering and Computer Sciences

Thermal design enhancements in a thermally limited compact notebook system are investigated in this paper. System temperature, power, and fan speed are characterized under a range of activity levels. A finite element model is developed, and validated against measurements. Design enhancements improve cooling with minimum intrusion to the existing mechanical design. A passive secondary heat pipe in the system reduces the CPU temperature by 5 $^{\circ}$C, and improves the system performance through increased CPU + Graphics and Memory Controller Hub (GMCH) thermal design power (TDP) by 6.4%. When such a secondary heat pipe is considered with an integrated off-the-shelf Peltier …

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A Neural Network Approach To Navigation Of A Mobile Robot And Obstacle Avoidance In Dynamic And Unknown Environments, Farhad Shamsfakhr, Bahram Sadeghi Bigham Jan 2017

A Neural Network Approach To Navigation Of A Mobile Robot And Obstacle Avoidance In Dynamic And Unknown Environments, Farhad Shamsfakhr, Bahram Sadeghi Bigham

Turkish Journal of Electrical Engineering and Computer Sciences

Mobile robot navigation and obstacle avoidance in dynamic and unknown environments is one of the most challenging problems in the field of robotics. Considering that a robot must be able to interact with the surrounding environment and respond to it in real time, and given the limited sensing range, inaccurate data, and noisy sensor readings, this problem becomes even more acute. In this paper, we attempt to develop a neural network approach equipped with statistical dimension reduction techniques to perform exact and fast robot navigation, as well as obstacle avoidance in such a manner. In order to increase the speed …

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Using Latent Semantic Analysis For Automated Keyword Extraction From Large Document Corpora, Tuğba Önal Süzek Jan 2017

Using Latent Semantic Analysis For Automated Keyword Extraction From Large Document Corpora, Tuğba Önal Süzek

Turkish Journal of Electrical Engineering and Computer Sciences

In this study, we describe a keyword extraction technique that uses latent semantic analysis (LSA) to identify semantically important single topic words or keywords. We compare our method against two other automated keyword extractors, Tf-idf (term frequency-inverse document frequency) and Metamap, using human-annotated keywords as a reference. Our results suggest that the LSA-based keyword extraction method performs comparably to the other techniques. Therefore, in an incremental update setting, the LSA-based keyword extraction method can be preferably used to extract keywords from text descriptions from big data when compared to existing keyword extraction methods.

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Eccentricity Fault Diagnosis In A Permanent Magnet Synchronous Motor Under Nonstationary Speed Conditions, Mustafa Eker, Mehmet Akar Jan 2017

Eccentricity Fault Diagnosis In A Permanent Magnet Synchronous Motor Under Nonstationary Speed Conditions, Mustafa Eker, Mehmet Akar

Turkish Journal of Electrical Engineering and Computer Sciences

Electric motor faults decrease production capacity and increase maintenance costs. Today, predictive detection based on real-time monitoring and fault detection is taking the place of periodic applications. In this study, a new method is presented for the detection of eccentricity faults in permanent magnet synchronous motors. The motor current and the rotor speed were monitored under stationary and nonstationary speed and different load conditions, after which the fault detection was carried out via angular domain-order tracking method. The obtained results were compared with traditional fast Fourier transform results. It was observed that the suggested method can successfully detect the fault …

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High-Pass/Low-Pass Section Design For 0$^{\Circ}$-360$^{\Circ}$ Lumped-Element Phase Shifters Via The Real Frequency Technique, Meti̇n Şengül Jan 2017

High-Pass/Low-Pass Section Design For 0$^{\Circ}$-360$^{\Circ}$ Lumped-Element Phase Shifters Via The Real Frequency Technique, Meti̇n Şengül

Turkish Journal of Electrical Engineering and Computer Sciences

In this paper, an algorithm based on the real frequency technique (RFT) is proposed to design high-pass and low-pass sections of a 0$^{\circ}$-360$^{\circ}$ wide range lumped-element phase shifter. The switching process, however, is not considered in this work. In the algorithm, it is enough to define the section type (high-pass or low-pass) and the number of elements in the sections; there is no need to select the exact circuit topologies for the high-pass and low-pass sections. This is a natural consequence of the proposed approach. Unlike in the methods described in the literature, there is also no need to derive …

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New Use Of The Hits Algorithm For Fast Web Page Classification, Mohamed Nadjib Meadi, Mohamed Chaouki Babahenini, Abdelmalik Taleb Ahmed Jan 2017

New Use Of The Hits Algorithm For Fast Web Page Classification, Mohamed Nadjib Meadi, Mohamed Chaouki Babahenini, Abdelmalik Taleb Ahmed

Turkish Journal of Electrical Engineering and Computer Sciences

The immense number of documents published on the web requires the utilization of automatic classifiers that allow organizing and obtaining information from these large resources. Typically, automatic web pages classifiers handle millions of web pages, tens of thousands of features, and hundreds of categories. Most of the classifiers use the vector space model to represent the dataset of web pages. The components of each vector are computed using the term frequency inversed document frequency (TFIDF) scheme. Unfortunately, TFIDF-based classifiers face the problem of the large-scale size of input data that leads to a long processing time and an increase in …

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Intellimote: A Hybrid Classifier For Classifying Learners' Emotion In A Distributed E-Learning Environment, Lopa Mandal, Rohan Das, Samar Bhattacharya, Pramatha Nath Basu Jan 2017

Intellimote: A Hybrid Classifier For Classifying Learners' Emotion In A Distributed E-Learning Environment, Lopa Mandal, Rohan Das, Samar Bhattacharya, Pramatha Nath Basu

Turkish Journal of Electrical Engineering and Computer Sciences

A huge collection of textual, graphical, audio, and video contents are readily available on the Internet to be used for the purpose of learning. Sentimental feedbacks of learners posted at the end of many of these contents may be considered as genuine reactions of the learners who have gone through the contents. Such learners' sentiments are important inputs for judging the acceptability of a learning material. Analyzing such feedbacks using sentiment analysis techniques can identify the best reusable learning contents that may be used for developing new courseware. This can significantly reduce the time and effort of authoring, which is …

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Electrocardiogram Signal Analysis For R-Peak Detection And Denoising With Hybrid Linearization And Principal Component Analysis, Harjeet Kaur, Rajni Rajni Jan 2017

Electrocardiogram Signal Analysis For R-Peak Detection And Denoising With Hybrid Linearization And Principal Component Analysis, Harjeet Kaur, Rajni Rajni

Turkish Journal of Electrical Engineering and Computer Sciences

In the areas of biomedical and healthcare, electrocardiogram (ECG) signal analysis is one of the major aspects of research. The accuracy in the detection of subtle characteristic features in ECG is of great significance. This paper deals with an algorithm based on hybrid linearization and principal component analysis for ECG signal denoising and R-peak detection. The ECG data have been taken from the MIT-BIH Arrhythmia Database for performance evaluation. The signal is denoised by applying the hybrid linearization method, which is an arrangement of the extended Kalman filter along with discrete wavelet transform, and then principal component analysis is employed …

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Offset-Free Adaptive Nonlinear Model Predictive Control With Disturbance Observer For Dc-Dc Buck Converters, Bahareh Vatankhah, Mohammad Farrokhi Jan 2017

Offset-Free Adaptive Nonlinear Model Predictive Control With Disturbance Observer For Dc-Dc Buck Converters, Bahareh Vatankhah, Mohammad Farrokhi

Turkish Journal of Electrical Engineering and Computer Sciences

The aim of this paper is to design a nonlinear model predictive control for DC-DC buck converters to track constant reference signals with zero steady-state error. The online trained neural network (NN) model is employed as the predictor and the steady-state error, which is called the offset, is studied in the presence of the changes in system parameters and the external disturbances. The stability of the closed-loop system is investigated using the Lyapunov direct theory. The proposed method can provide offset-free behavior in the presence of constant disturbances. For rejecting nonconstant disturbances, a nonlinear disturbance observer based on the NN …

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Modified Control Of The Matrix Converter-Based Drive For Voltage Sag Impact Reduction, Gytis Petrauskas, Gytis Svinkunas Jan 2017

Modified Control Of The Matrix Converter-Based Drive For Voltage Sag Impact Reduction, Gytis Petrauskas, Gytis Svinkunas

Turkish Journal of Electrical Engineering and Computer Sciences

Faults in transmission and distribution networks often cause voltage sags. Direct matrix converter (DMC)-based drives are a new generation of electrical drives. Unlike the conventional two-stage diode supply-side inverter drive, the DMC drive has no direct current (DC) link capacitor and no capacitor charging-time delay before operation. The absence of a DC link makes the DMC-based drive more sensitive to voltage sags. The above-mentioned faults in transmission and distribution networks could degrade the DMC drive's performance and reliability. This paper investigates possible kinds and levels of voltage sags, dependency on network configuration, and the behavior of the DMC-based drive under …

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New Edta-Based Drug Delivery Carrier, Nathapong Pangkom Jan 2017

New Edta-Based Drug Delivery Carrier, Nathapong Pangkom

Chulalongkorn University Theses and Dissertations (Chula ETD)

Most of the anticancer drugs are insoluble in water, unspecified to target site and degradable under acidic conditions in the stomach, resulting in decreasing their activities and increasing the side effects. To overcome these problems, drug delivery carriers were used to overcome these problems. Most of the drug delivery carriers were prepared by polymeric micelle systems. However, that of polymeric micelle systems are difficult to synthesize into the random polymers, where different units are aligned on a polymer chain in a random manner, immature drug-incorporation technology and possible chronic liver toxicity due to slow metabolic process. Therefore, the enhancement of …

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Fluoride Encapsulation In Calcium Matrix, Piyada Dissara Jan 2017

Fluoride Encapsulation In Calcium Matrix, Piyada Dissara

Chulalongkorn University Theses and Dissertations (Chula ETD)

Fluoride ion (F-) is an important ingredient in a toothpaste. It protects caries by reacting with hydroxyapatite [Ca10(PO)4(OH)2] in tooth enamel to form insoluble fluorapatite [Ca10(PO)4(F)2]. Unfortunately, F- also easily interacts with calcium species in a toothpaste, and then it is deactivated. In this work, we focus on the encapsulation of F- in a shellac bead by using a simple extrusion method. To construct shellac beads, an aqueous solution of F- is injected into an ethanolic solution of shellac. The shellac beads are formed due to insolubility of shellac in water. Then, the beads are transferred into DI water for …

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Ferrocene-Bearing Tea Polyphenol Particles As Anticancer Drug Carriers, Punnawich Phaiyarin Jan 2017

Ferrocene-Bearing Tea Polyphenol Particles As Anticancer Drug Carriers, Punnawich Phaiyarin

Chulalongkorn University Theses and Dissertations (Chula ETD)

Ferrocene is a redox moiety that can be positively charged upon being oxidized. Thus, it is possible to use this moiety to make a polymer platform that is redox responsive regarding their water solubility. Here we prepared polymerized EGCG nanoparticles (pEGCG) and polymerized EGCG gum (pEGCG-gum) from tea polyphenol EGCG. Ferrocene was grafted onto the polymerized tea polyphenol and the obtained polymers were allowed to self-assemble into water-insoluble and indispersible sub-micron particles. The water-insoluble ferrocene-bearing particles became water-dispersible particles with nanometer sizes upon being oxidized by hydrogen peroxide. The oxidized particles, Fc-pEG-gum can inhibit growth of HepG2 liver cancer cells …

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Colorimetric Detection Of Cyanide Ions Using Complex Formation And Ctab-Coated Silica, Patita Salee Jan 2017

Colorimetric Detection Of Cyanide Ions Using Complex Formation And Ctab-Coated Silica, Patita Salee

Chulalongkorn University Theses and Dissertations (Chula ETD)

This research presents a new colorimetric method of cyanide detection in solution and water samples based on the extraction of dicyano-bis-(1,10-phenanthroline)-iron(II) complex onto CTAB-coated silica. The complex was formed at pH 10 by using phosphate buffer via the complex formation between tris-(1,10-phenanthroline)-Iron(II) (ferroin) with cyanide ions in CTAB media. When the complex was extracted onto CTAB-coated silica, it resulted in a color change of the material from pale yellow to purple. The changing of color corresponded to cyanide concentration which could be observed by naked-eyes and the color intensity was determined by Image J. The effects of various parameters were …

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Characterization Of Aroma-Active Volatile Compounds In Tom Yum Soup By Gas Chromatography-Mass Spectrometry Combined With Sensory Evaluation Techniques, Pannipa Janta Jan 2017

Characterization Of Aroma-Active Volatile Compounds In Tom Yum Soup By Gas Chromatography-Mass Spectrometry Combined With Sensory Evaluation Techniques, Pannipa Janta

Chulalongkorn University Theses and Dissertations (Chula ETD)

Gas chromatography-mass spectrometry/olfactometry coupled with headspace-solid phase microextraction (HS-SPME-GC-O/MS) was applied for the characterization of volatile compounds in Tom Yum soup and its individual ingredients including lemongrass, kaffir lime leaf, chili, fish sauce and lime juice. Using HS-SPME with a 50/30 µm DVB/CAR/PDMS fiber and an extraction temperature of 40 °C for 50 min, along with an HP-5MS capillary column programmed from 50 to 200 °C at 3 °C/min and an MS electron impact ionization at -70 eV, 101 peaks in the HS-SPME-GC-MS chromatogram of Tom Yum soup were detected, and 96 volatile compounds were identified including alcohols, aldehydes, esters, …

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Preparation Of Rigid Polyurethane Foams Catalyzed By Metal-Asparagine And Metal-Threonine Complexes, Nuttiya Jintana Jan 2017

Preparation Of Rigid Polyurethane Foams Catalyzed By Metal-Asparagine And Metal-Threonine Complexes, Nuttiya Jintana

Chulalongkorn University Theses and Dissertations (Chula ETD)

This research aimed to synthesize metal-amino acid complexes in the form of aqueous solutions to serve as new catalysts for the preparation of rigid polyurethane foams. Aqueous solutions of metal-amino acid complexes were prepared from the reaction of metal acetates with amino acids and water was used as a solvent. Metal acetates employed were copper acetate and zinc acetate. Amino acids employed were asparagine (Asn) and threonine (Thr). Both amino acids are odorless and non-toxic. UV-Vis spectroscopy, FTIR spectroscopy and mass spectrometry were used to characterize metal-amino acid complexes. Metal-amino acid complexes, namely Zn(Asn)₂, Zn(Thr)₂, Cu(Asn)₂ and Cu(Thr)₂ (where Asn …

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Fabrication Of Silver Nanofilament Based On Silver Sulfide Solid Electrolyte For Tip-Enhanced Raman Spectroscopy, Phichaya Fueaimi Jan 2017

Fabrication Of Silver Nanofilament Based On Silver Sulfide Solid Electrolyte For Tip-Enhanced Raman Spectroscopy, Phichaya Fueaimi

Chulalongkorn University Theses and Dissertations (Chula ETD)

Surface science analysis is the crucial fundamental of nanoscale study. The techniques combined morphological and compositional study on the surface are the promising technique. Tip-enhanced Raman spectroscopy (TERS) is the coupling of atomic force microscopy (AFM) and Raman spectroscopy which give the 3D- images and bonding information in ambient conditions. Furthermore, TERS tip is an ideal tool for the high enhancement and spatial resolution. Nowadays, TERS tip fabrication is still challenged. There are three main challenges that are high enhancement factor of the TERS tip, reproducibility of the tip and in-depth understanding of TERS process. We introduce the simple method …

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Colorimetric Detection Of Cysteine Using Silver-Hydroxyapatite Nanoparticles, Retno Prasetia Jan 2017

Colorimetric Detection Of Cysteine Using Silver-Hydroxyapatite Nanoparticles, Retno Prasetia

Chulalongkorn University Theses and Dissertations (Chula ETD)

Cysteine is a sulphur-containing amino acid that acts as an effective antioxidant in human body. An excessive amount of cysteine leads to cystine formation that causes the stone formation in kidney, bladder, and ureters. A new method was developed for detection of cysteine in urine samples based on the aggregation of silver nanoparticles (AgNPs) on Hydroxyapatite (HAp) in the presence of cysteine. Transmission Electron Microscope (TEM) was used to observe the morphology of prepared HAp and AgNPs on HAp. The presence of cysteine of different concentrations resulted in different cluster sizes of AgNPs on HAp and hence different solid color. …

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Synthesis And Supramolecular Polymerization Of Peptide Nucleic Acid-Containing Monomer, Ruttiyakorn Donthongkwa Jan 2017

Synthesis And Supramolecular Polymerization Of Peptide Nucleic Acid-Containing Monomer, Ruttiyakorn Donthongkwa

Chulalongkorn University Theses and Dissertations (Chula ETD)

Nucleobase-induced self-assembly interaction, have gained much attention as potential non-covalent driving force for generating interesting assembled structures. Pyrrolidinyl peptide nucleic acid (PNA), with (2′R,4′R)-prolyl/(1S,2S)-2-aminocyclopentanecarboxylic acid backbone (acpcPNA) has shown the recognition with complementary nucleic acids following Watson-Crick base rules. Another PNA system having different stereochemistry on proline ring with a backbone of (2′R,4′S)-prolyl/(1S,2S)-2-aminocyclopentanecarboxylic acid backbone (epi-acpcPNA) can undergo self-pairing. Here in this work, both acpcPNA- and epi-acpcPNA-functionalized monomers consisting of two PNA segments joined together by a flexible polyethylene glycol linker were prepared on solid support, purified by high performance liquid chromatography (HPLC) and characterized by MALDI-TOF mass spectrometry. The …

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Synthesis And Cytotoxicity Evaluation Of Gold Nanoparticles/Pullulan Derivatives For Cancer Treatment, Sakchai Laksee Jan 2017

Synthesis And Cytotoxicity Evaluation Of Gold Nanoparticles/Pullulan Derivatives For Cancer Treatment, Sakchai Laksee

Chulalongkorn University Theses and Dissertations (Chula ETD)

This study focused on the development of multifunctional gold nanoparticles (AuNPs) using pullulan derivatives as a trifunctional reducing, stabilizing and capping agent for targeted delivery of camptothecin (CPT) or doxorubicin (DOX) in order to enhance their efficacy and reduce side effects. The surface of AuNPs was functionalized to contain 3 beneficial components on pullulan as followed: (i) quat188 as a positive charge to increase cellular uptake and activities, (ii) para-aminobenzoic acid (PABA) as a hydrophobic molecule to enhance biocompatibility, and (iii) folic acid (FA) as a targeting ligand to bind with folate receptor on cancerous cell membranes and enhance intracellular …

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Functionalization Of Chemical Vapor Deposition-Grown Graphene, Shobnibhit Chatmaneerungcharoen Jan 2017

Functionalization Of Chemical Vapor Deposition-Grown Graphene, Shobnibhit Chatmaneerungcharoen

Chulalongkorn University Theses and Dissertations (Chula ETD)

Graphene has been a wonder material since its discovery in 2004. Due to its interesting properties such as excellent thermal and electrical conductivities, flexibility and high strength, many researchers around the globe have turned their attention to this carbon allotrope. To synthesize graphene with high quality, chemical vapor deposition (CVD) is an industrially feasible method. Generally, methane is the most widely used carbon precursor. However, high purity grade is expensive in Thailand. Instead, acetylene should be a possible replacement. Moreover, operating CVD at atmospheric pressure would also dramatically reduce the cost. Still, growth conditions need to be optimized for new …

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Bioactive Compounds From Lichens And Mycobionts In Trypetheliaceae Family, Suekanya Jarupinthusophon Jan 2017

Bioactive Compounds From Lichens And Mycobionts In Trypetheliaceae Family, Suekanya Jarupinthusophon

Chulalongkorn University Theses and Dissertations (Chula ETD)

Chemical constituents of two lichens Marcelaria cumingii and Trypethelium subeluteriae, and four cultured mycobionts from M. cumingii, T. platystomum, T. eluteriae and Trypethelium sp. (Trypetheliaceae) were explored. Their secondary metabolites were structurally elucidated by spectroscopic methods as xanthones, anthraquinones, naphthoquinones and phenalenones. Lichexanthone, parietin, xanthorin and emodin were disclosed as constituents of lichens M. cumingii. Whereas, two anthraquinones: parietin and emodin could be isolated from T. subeluteriae together with another anthraquinone, haematommone. The chemical compositions of four cultured mycobionts were found to totally differ from those from lichen. The phenalenone bipolaride C was derived from T. platystomum while two 1,2-naphthoquinones, …

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Colorimetric Determination Of Thiocyanate Ion Using Modified Polymer Resins, Sujinda Khaosaard Jan 2017

Colorimetric Determination Of Thiocyanate Ion Using Modified Polymer Resins, Sujinda Khaosaard

Chulalongkorn University Theses and Dissertations (Chula ETD)

A new method for thiocyanate determination in milk samples based on the formation of dithiocyanato dipyridine copper(II) [Cu(SCN)2(Py)2] complex on polymer resin surface is proposed. Amberlite XAD-7 resin on was modified with copper-pyridine complex and used as the material for detection. The color of resin changed from blue to green with the increase of thiocyanate concentration. It could be observed by naked-eye and the color intensity used as quantitative data was measured via Image-J software. The effect of various parameters was investigated including Cu2+ concentration, time for resin modification with reagents, sample volume, detection time and pyridine volume. Under the …

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