Open Access. Powered by Scholars. Published by Universities.®

Digital Commons Network™

Open Access. Powered by Scholars. Published by Universities.®

2018

Discipline
Institution
Keyword
Publication
Publication Type
File Type

Articles 23221 - 23250 of 25768

Full-Text Articles in Entire DC Network

Improved Transient Response Capacitor Less Low Dropout Regulator Employing Adaptive Bias And Bulk Modulation, Suresh Alapati, Sreehari Rao Patri Jan 2018

Improved Transient Response Capacitor Less Low Dropout Regulator Employing Adaptive Bias And Bulk Modulation, Suresh Alapati, Sreehari Rao Patri

Turkish Journal of Electrical Engineering and Computer Sciences

This paper presents a low quiescent current, fast settling time, and adaptively biased capacitor less low-dropout (LDO) regulator. The topology involves a segmented pass transistor with bulk modulation and adaptively biased current control stages to improve the transient performance. The bulk modulation of the pass transistor assists in fast settling of the output voltage. The frequency compensation makes the LDO voltage regulator stable adaptively over load current transitions. In addition, the biasing stage is designed such that it adapts to the load transitions while consuming the quiescent current abstemiously. This arrangement further improves settling time to be within 1 µs …

Go to article

Design Of An On-Chip Hilbert Fractal Inductor Using An Improved Feed Forward Neural Network For Si Rfics, Akhendra Kumar Padavala, Bheema Rao Nistala Jan 2018

Design Of An On-Chip Hilbert Fractal Inductor Using An Improved Feed Forward Neural Network For Si Rfics, Akhendra Kumar Padavala, Bheema Rao Nistala

Turkish Journal of Electrical Engineering and Computer Sciences

This paper presents an efficient modeling of Hilbert fractal inductors by improved feed forward neural network trained hybrid particle swarm optimization and gravitational search algorithm (FNNPSOGSA). The proposed model computes the effective inductance value (L) and quality factor (Q) of Hilbert fractal inductors with metal trace width, effective fractal length, frequency, and oxide thickness as input parameters. In contrast to the traditional feed forward neural network, the proposed FNNPSOGSA has been designed with fewer hidden neurons with much-enhanced learning and generalization capabilities. As a consequence, the proposed model achieves better speed and is as accurate as electromagnetic simulations. From the …

Go to article

An Enhanced Grey Wolf Optimization Algorithm With Improved Exploration Ability For Analog Circuit Design Automation, M A Mushahhid Majeed, Sreehari Rao Patri Jan 2018

An Enhanced Grey Wolf Optimization Algorithm With Improved Exploration Ability For Analog Circuit Design Automation, M A Mushahhid Majeed, Sreehari Rao Patri

Turkish Journal of Electrical Engineering and Computer Sciences

A novel circuit sizing technique with improved accuracy and efficiency is proposed to resolve the sizing issues in the analog circuit design. The grey wolf optimization (GWO) algorithm has the total number of iterations divided equally for exploration and exploitation, overlooking the impact of balance between these two phases, aimed for the convergence at a globally optimal solution. An enhanced version of a typical GWO algorithm termed as enhanced grey wolf optimization (EGWO) algorithm is presented with improved exploration ability and is successfully applied in analog circuit design. A set of 23 classical benchmark functions is evaluated and the outcomes …

Go to article

Design Of A Fractional Order Pid Controller With Application To An Induction Motor Drive, Ashraf Saleem, Hisham Soliman, Serein Al-Ratrout, Mostefa Mesbah Jan 2018

Design Of A Fractional Order Pid Controller With Application To An Induction Motor Drive, Ashraf Saleem, Hisham Soliman, Serein Al-Ratrout, Mostefa Mesbah

Turkish Journal of Electrical Engineering and Computer Sciences

In this paper, a new method for designing a fractional-order proportional-integral-derivative (FO-PID) controller with an application to an induction motor drive is proposed. In the proposed method, the motor drive is modeled using an autoregressive with exogenous input (ARX) model whose parameters are experimentally identified using real I/O data. A genetic algorithm is then used to find the FO-PID parameters. To guarantee the robustness of the controller against load variations, minimax optimization is adopted. To validate the results, the proposed controller is applied to a real-life motor drive using a hardware-in-the-loop (HIL) simulator. The experimental results show that the proposed …

Go to article

Human Sleep Scoring Based On K-Nearest Neighbors, Shahnawaz Qureshi, Seppo Karrila, Sirirut Vanichayobon Jan 2018

Human Sleep Scoring Based On K-Nearest Neighbors, Shahnawaz Qureshi, Seppo Karrila, Sirirut Vanichayobon

Turkish Journal of Electrical Engineering and Computer Sciences

Human sleep is one of the essential indicators that gauge the overall health and well-being. Presently, it is common for people to face issues related to sleep. Various biomedical signals including electroencephalogram (EEG), electrooculography (EMG), and electrooculography (EOG) are utilized in the diagnosis and during the treatment of sleep disorder cases. An automatic classification to diagnose sleep problems can help in the analysis of sleep EEG data. In this current study, an effort is made to classify the sleep stages from a single EEG channel (C4-A1) based on K-nearest neighbors (K-NN) with three alternative distance metrics. The Euclidean distance is …

Go to article

Sign Language Recognition With Multi Feature Fusion And Ann Classifier, Sunitha Ravi, Maloji Suman, Polurie Venkata Vijay Kishore, Kiran Kumar Eepuri Jan 2018

Sign Language Recognition With Multi Feature Fusion And Ann Classifier, Sunitha Ravi, Maloji Suman, Polurie Venkata Vijay Kishore, Kiran Kumar Eepuri

Turkish Journal of Electrical Engineering and Computer Sciences

Extracting and recognizing complex human movements such as sign language gestures from video sequences is a challenging task. In this paper this kind of a difficult problem is approached with Indian sign language (ISL) videos. A new segmentation algorithm is developed by fusion of features from discrete wavelet transform (DWT) and local binary pattern (LBP). A 2D point cloud is formed from fused features, which represent the local hand shapes in consecutive video frames. We validate the proposed feature extraction model with state of the art features such as HOG, SIFT and SURF for each sign video on the same …

Go to article

Improved Method Of Heuristic Classification Of Vowels From An Acoustic Signal, Josef Krocil, Zdenek Machacek, Jiri Koziorek, Radek Martinek, Jan Nedoma, Marcel Fajkus Jan 2018

Improved Method Of Heuristic Classification Of Vowels From An Acoustic Signal, Josef Krocil, Zdenek Machacek, Jiri Koziorek, Radek Martinek, Jan Nedoma, Marcel Fajkus

Turkish Journal of Electrical Engineering and Computer Sciences

This paper describes research in the field of the improved methodology of the classification of vowels /a, a:/, /$\varepsilon$, $\varepsilon$:/, /ı, i:/, /o, o:/, and /u, u:/ (vowel symbols according to IPA, i.e. International Phonetic Alphabet). The aim is to develop an improved method enabling the automatic allocation of vowel symbols to the corresponding time segments of acoustic recordings of an undisturbed speech signal. The combined classification method is based on finding frequencies of the first two local maxims (formants) in a smoothed linear predictive amplitude spectrum (LPC, linear predictive coding) and zero-crossing values of each speech active voiced short-term …

Go to article

Fpga Implementation Of A Low-Power And Area-Efficient State-Table-Based Compression Algorithm For Dslr Cameras, Mohd Rafi Lone, Najeeb Ud Din Hakim Jan 2018

Fpga Implementation Of A Low-Power And Area-Efficient State-Table-Based Compression Algorithm For Dslr Cameras, Mohd Rafi Lone, Najeeb Ud Din Hakim

Turkish Journal of Electrical Engineering and Computer Sciences

Small image acquisition devices like digital single lens reflex (DSLR) cameras most commonly use Joint Photographic Expects Group (JPEG) coding standard for lossy compression. Although JPEG is a simple coding standard, its compression efficiency is very low as compared to any typical state-of-the-art image coding standards like set partitioning in hierarchical trees (SPIHT). In this paper, a novel state-table-based SPIHT (STS) algorithm and its field programmable gate array (FPGA) implementation is proposed. The STS uses two small state-tables and two extremely small lists. The STS not only provides better compression efficiency than the state-of-the-art JPEG 2000 at high bit rates …

Go to article

Path Loss Model For Indoor Emergency Stairwell Environment At Millimeter Wave Band For 5g Network, Ahmed Mohammed Alsamman, Tharek Abd Rahman, Mohd Nour Hindia, Jamal Nasir Jan 2018

Path Loss Model For Indoor Emergency Stairwell Environment At Millimeter Wave Band For 5g Network, Ahmed Mohammed Alsamman, Tharek Abd Rahman, Mohd Nour Hindia, Jamal Nasir

Turkish Journal of Electrical Engineering and Computer Sciences

The unused millimeter-wave (mmWave) spectrum offers a superb opportunity to increase mobile broadband capacity due to the enormous amount of available bandwidth. Different candidate operating frequencies for 5G wireless networks are available at the mmWave band. For 5G wireless networks, the emergency case is one of the applications. This paper presents the outcome of indoor emergency stairwell measurement campaigns for 5G system at 26 GHz, 28 GHz, 32 GHz, and 38 GHz, which were conducted at the University Technology Malaysia, Kuala Lumpur, Malaysia. To effectively evaluate the performance of 5G wireless systems in these different bands, single- and multifrequency path …

Go to article

Artificial Immune System Based Wastewater Parameter Estimation, Cengi̇z Sertkaya, Ni̇lüfer Yurtay Jan 2018

Artificial Immune System Based Wastewater Parameter Estimation, Cengi̇z Sertkaya, Ni̇lüfer Yurtay

Turkish Journal of Electrical Engineering and Computer Sciences

The basis of a wastewater treatment system is to achieve the desired characteristics of the wastewater treatment process. An estimation of the obtained wastewater treatment characteristics provides the information needed to set up the current process steps, and it is important to have an optimum treatment. In this study, an artificial immune system (AIS) structure is developed to estimate important wastewater output parameters such as pH, DBO, DQO, and SS for the first time. The proposed AIS models are based on the clonal selection principle, and the dataset is provided from the University of California Irvine (UCI) Machine Learning Library. …

Go to article

Horizontal Diversity In Test Generation For High Fault Coverage, Arbab Alamgir, Abu Khari Bin A'Ain, Norlina Paraman, Usman Ullah Sheikh, Ian Grout Jan 2018

Horizontal Diversity In Test Generation For High Fault Coverage, Arbab Alamgir, Abu Khari Bin A'Ain, Norlina Paraman, Usman Ullah Sheikh, Ian Grout

Turkish Journal of Electrical Engineering and Computer Sciences

Determination of the most appropriate test set is critical for high fault coverage in testing of digital integrated circuits. Among black-box approaches, random testing is popular due to its simplicity and cost effectiveness. An extension to random testing is antirandom that improves fault detection by maximizing the distance of every subsequent test pattern from the set of previously applied test patterns. Antirandom testing uses total Hamming distance and total cartesian distance as distance metrics to maximize diversity in the testing sequence. However, the algorithm for the antirandom test set generation has two major issues. Firstly, there is no selection criteria …

Go to article

Computational Fluid Dynamics Modeling Of The Climate Inside A Chicken House, Nuttaphon Kanjanaudomsuk Jan 2018

Computational Fluid Dynamics Modeling Of The Climate Inside A Chicken House, Nuttaphon Kanjanaudomsuk

Chulalongkorn University Theses and Dissertations (Chula ETD)

Nowadays, most of chicken products are from a closed house system. Climate inside such chicken house can significantly affect chicken welfare and its productivity. Moreover, Thailand is in a tropical region where thermal stress is easily occurred. Suitable operating condition and chicken house design can help improve interior climate which can be evaluated by computational fluid dynamics (CFD) modeling technique. In this study, realizable k-ε model, energy conservation and species transport equations were applied to simulate the air velocity, temperature and relative humidity, respectively, inside the chicken house. The model was validated with measured air velocity, temperature and relative humidity …

Go to article

Design Of Solid Oxide Fuel Cell-Molten Carbonate Fuel Cell Combined System For Power Generation And Carbon Dioxide Emission Reduction, Prathak Jienkulsawad Jan 2018

Design Of Solid Oxide Fuel Cell-Molten Carbonate Fuel Cell Combined System For Power Generation And Carbon Dioxide Emission Reduction, Prathak Jienkulsawad

Chulalongkorn University Theses and Dissertations (Chula ETD)

This research concentrates on the design and performance analysis of a solid oxide fuel cell (SOFC) and a molten carbonate fuel cell (MCFC) integrated system with using methane as fuel. Because SOFCs cannot completely use their fuel, there is remaining fuel leaving the system. In addition, the exhaust gas from an SOFC can be directly fed into an MCFC. The integrated fuel cell system shows an electrical efficiency of 55.22%, which is higher than a single fuel cell system. Fuel utilization of both fuel cells, SOFC temperature dramatically affect the performance of the integrated system. Four configurations were next proposed …

Go to article

Synthesis Of Black Titanium Dioxide And Effect Of Calcination Conditions And Reducing Agent On Photocatalytic Degradation Of Methyl Orange, Saran Saensook Jan 2018

Synthesis Of Black Titanium Dioxide And Effect Of Calcination Conditions And Reducing Agent On Photocatalytic Degradation Of Methyl Orange, Saran Saensook

Chulalongkorn University Theses and Dissertations (Chula ETD)

This research studied the synthesis and application of black titanium dioxide in the photocatalytic degradation of methyl orange (MO). First, titanium dioxide was prepared via a sol-gel method. Then sodium borohydride was used as the reducing agent in order to synthesize black titanium dioxide. Thus, a 2x2x3 factorial experimental design was employed to assess the significance of the following three factors: (A) calcination temperature (400 and 500 °C); (B) calcination time (5 and 10 h); and (C) the molar ratio of NaBH4 to TiO2 used (0:1, 0.5:1, and 1:1). The removal of MO under UV and visible light were the …

Go to article

Carbon Dioxide Capture On Nitrogen-Doped Carbon Nanoparticle Derived From Aromatic Compounds Via Solution Plasma And Nitridation, Phuwadej Pornaroontham Jan 2018

Carbon Dioxide Capture On Nitrogen-Doped Carbon Nanoparticle Derived From Aromatic Compounds Via Solution Plasma And Nitridation, Phuwadej Pornaroontham

Chulalongkorn University Theses and Dissertations (Chula ETD)

The carbon dioxide (CO2) adsorption on nanocarbon (C), oxygen-doped nanocarbon synthesized from benzene and a mixture of benzene and metal working fluid (MWF), respectively, via solution plasma process (SPP) have been revealed in this study. Firstly, they showed low CO2 adsorption capacity at 25 °C. However, their capacities were enhanced by nitridation under ammonia atmosphere at high temperature. The maximum CO2 adsorption capacity of 1.63 mmol g-1 was achieved on nitrogen-oxygen-codoped nanocarbon obtained from SPP discharging a mixture containing 15 vol% MWF nitrided at 800 °C (noC15(800)). The characterizations revealed that the micropososity and nitrogen functionality on the adsorbent are …

Go to article

Computational Fluid Dynamics Of Fluid Transport And Deposition Of Particles Under Unsteady Flow In Human Fluid System, Ratchanon Piemjaiswang Jan 2018

Computational Fluid Dynamics Of Fluid Transport And Deposition Of Particles Under Unsteady Flow In Human Fluid System, Ratchanon Piemjaiswang

Chulalongkorn University Theses and Dissertations (Chula ETD)

Computational fluid dynamics has been widely used to investigate flow phenomena in many different applications. This study focuses on the development of computational fluid dynamic model in biomedical applications, including the flow within human respiratory system and the flow within human circulating system. For the model of respiratory system, electrostatic charge model was coupled, and the effect of breathing frequency was investigated. The accomplishment of the study will gain better understanding of the hydrodynamics when applying the electrostatic field, and will use to identify the potential aerosol deposition location. The aerosol properties and morphologies were also considered their effect on …

Go to article

Development Of Optical Sensor For Detection Of Chloride Ions And Electrochemical Sensor For Detection Of Clinical Indicators, Abdulhadee Yakoh Jan 2018

Development Of Optical Sensor For Detection Of Chloride Ions And Electrochemical Sensor For Detection Of Clinical Indicators, Abdulhadee Yakoh

Chulalongkorn University Theses and Dissertations (Chula ETD)

This dissertation concentrated on the development of nanomaterials-based miniaturized platforms for the detection of some important compounds/indicators from environmental, pharmaceutical, and clinical application. This dissertation can be classified into two main parts: (1) development of nanomaterials-based miniaturized platforms for optical sensing application, and (2) development of nanomaterials-based miniaturized platforms for electrochemical sensing applications. In the first part, two sub-sections were discussed. For the first sub-section, the paper-based colorimetric sensor for chloride ion determination using silver nanoprisms was developed. Using a smartphone as an optical readout, the color change from the oxidative etching of the silver nanoprisms to the silver nanospheres …

Go to article

Development Of Sr₂Fetio[₆-Delta] Electrode For Solid Oxide Fuel Cell, Ausa Potong Jan 2018

Development Of Sr₂Fetio[₆-Delta] Electrode For Solid Oxide Fuel Cell, Ausa Potong

Chulalongkorn University Theses and Dissertations (Chula ETD)

Sr₂FeTi₁-x(Nb,V)xO₆ (x=0.05-0.50) double perovskites have been synthesized by the substitution of Nb and V on Ti sites of Sr₂FeTiO₆ (SFT) and tested as electrode for intermediate temperature solid oxide fuel cell (IT-SOFC). The XRD analyses indicated Sr₂FeTi₀.₉₅Nb₀.₀₅O₆ and Sr₂FeTi₀.₉₅V₀.₀₅O₆ were pure and the impurities, Sr(FeNb) ₀.₅O₃ and Sr3(VO4) ₂, were found with the increasing of Nb and V contents in SFT. By small addition of Nb and V in SFT, the electrical conductivity and electrochemical property of SFT was improved. Among the various oxide examined, Sr₂FeTi₀.₉₅Nb₀.₀₅O₆ and Sr₂FeTi₀.₉₅V₀.₀₅O₆ showed the highest electrical conductivity of 2.44 and 3.93 S cm⁻¹, respectively, …

Go to article

Carbon Sorbent Reinforced Hollow Fiber Membrane Microextraction For Determination Of Trace Polar Organic Compounds, Chanatda Worawit Jan 2018

Carbon Sorbent Reinforced Hollow Fiber Membrane Microextraction For Determination Of Trace Polar Organic Compounds, Chanatda Worawit

Chulalongkorn University Theses and Dissertations (Chula ETD)

This work presents a proof of concept that hollow fiber liquid phase microextraction reinforced with carbon nanomaterials would improve the extraction efficiency of small and relatively polar organic compounds. Several types of carbon sorbents such as graphite, graphene, carbon nanofiber were studied. In research I, the hollow fiber membrane reinforced with graphite was developed for liquid phase microextraction of trihalomethanes in water samples. Parameters affecting extraction efficiency including organic solvent as supported liquid membrane, amount of loaded graphite and extraction time were investigated and optimized. The working range of 0.2-120 µg L-1 was obtained in 10 min extraction with good …

Go to article

Development Of Electrochemical And Colorimetric Methods Using Inorganic Nanomaterials For Detection Of Biological And Environmental Compounds, Chanika Pinyorospathum Jan 2018

Development Of Electrochemical And Colorimetric Methods Using Inorganic Nanomaterials For Detection Of Biological And Environmental Compounds, Chanika Pinyorospathum

Chulalongkorn University Theses and Dissertations (Chula ETD)

This research comprised of 2 parts including (1) lab-on-paper coupled with electrochemical method for C-reactive protein and colorimetric detection for phosphate ions and (2) the development of chromatographic techniques and its applications. In each part, it can be classified in 2 works. The first work of lab-on-paper is the electrochemical sensor that was fabricated from phosphorylcholine assembled electrodeposited gold nanoparticles onto screen-printed carbon electrode for C-reactive protein detection. Current of ferrocyanide decrease linearly when increase C-reactive protein concentration from 5.0 – 5000 µg L⁻¹. The calculated detection limit equals 1.60 µg L⁻¹. The final part of lab-on-paper is the colorimetry …

Go to article

Study Of Substitution Reaction On Ring A Of Estradiol, Chanoknun Boonyaratsewee Jan 2018

Study Of Substitution Reaction On Ring A Of Estradiol, Chanoknun Boonyaratsewee

Chulalongkorn University Theses and Dissertations (Chula ETD)

Estradiol-conjugated anticancer drugs are the effective strategy that could specifically combat breast cancer cells, while minimizing the toxicity of the drug toward normal cells. Estradiol has been previously conjugated with drugs mostly at rings B, C and D. Functionalizations at ring A of estradiol introduce new types of conjugated drugs that could improve both the selectivity and efficiency in binding with estrogen receptor (ER). Using 4-cresol as the model, the nitration at meta-position was achieved, although with unsatisfied result of only 6% overall yield of the product. The practical results derived from diazo coupling on ortho-position of 4-cresol, which led …

Go to article

Molecularly Imprinted Polymer Modified Optical Fiber Sensor Based On Surface Plasmon Resonance Spectroscopy For Determination Of Atrazine, Chidchanok Tabtimhin Jan 2018

Molecularly Imprinted Polymer Modified Optical Fiber Sensor Based On Surface Plasmon Resonance Spectroscopy For Determination Of Atrazine, Chidchanok Tabtimhin

Chulalongkorn University Theses and Dissertations (Chula ETD)

A sensitive sensor device based on surface plasmon resonance (SPR) spectroscopy was developed on an optical fiber and made to be selective to atrazine by molecularly imprinted polymer. The SPR probe was fabricated by deposition of gold nanoparticles on the uncladed surface of an optical fiber by self-assembly method. The size and distribution of gold nanoparticle was optimized by varying the soaking time of the optical fiber. The surface was further modified for selective sensing of atrazine with the molecularly imprinted polymer (MIP). The MIP was synthesized via 2 methods, the first was thermal polymerization method, the MIP was then …

Go to article

Enzymatic Reaction Based Biosensor For Specific Detection Of Organophosphate Pesticides, Chonticha Sahub Jan 2018

Enzymatic Reaction Based Biosensor For Specific Detection Of Organophosphate Pesticides, Chonticha Sahub

Chulalongkorn University Theses and Dissertations (Chula ETD)

This research aims to design and develop two-biosensor platforms based on graphene quantum dots (GQDs) via enzymatic reaction for determining organophosphate pesticides (OPs). A first platform consisting of GQDs and active enzyme, GQDs/Enz platform, is simply fabricated in aqueous solution. Ongoing development of GQDs/Enz platform for effective OPs sensing by hybrid hydrogel (GQDs/Enz/Gels) was of great interest to improve the sensitivity and enzyme stability under the benefit of easy to be used for sensing approach. The GQDs/Enz and GQDs/Enz/Gels were constructed and characterized by general methods such as FT-IR, SEM and TEM. Based on the concept, H2O2 generated in situ …

Go to article

Adsorption Of Tetrachloroaluminate Ion On Graphene Quantum Dots, Fadjar Mulya Jan 2018

Adsorption Of Tetrachloroaluminate Ion On Graphene Quantum Dots, Fadjar Mulya

Chulalongkorn University Theses and Dissertations (Chula ETD)

The important thing in the mechanism of aluminium ion battery is the fast adsorption of tetrachloroaluminate [AlCl4]- on intercalation sites of bulk graphite which can increase the efficiency and lifetime of the battery. In this study, we modeled graphene quantum dots (GQDs) as cathode material. For the adsorption of [AlCl4]-, coronene (C24H12) and circumcoronene (C54H18) were used as the model of GQDs with three types of adsorption sites and standing positions. The charge of GQDs was modified to be 0 and +1 to address discharging and charging conditions. The distance between chlorine atom and carbon atom of GQDs was found …

Go to article

Green Synthesis Of Guanidines Directly From Thiourea, Jakkrit Srisa Jan 2018

Green Synthesis Of Guanidines Directly From Thiourea, Jakkrit Srisa

Chulalongkorn University Theses and Dissertations (Chula ETD)

In this work, one-pot synthesis of guanidines directly from isothiocyanates using DIB (diacetoxyiodobenzene) as a desulfurizing agent under a micellar condition in water was developed. The optimization study revealed that the use of 1wt%TPGS-750-M as a surfactant with NaOH as a base at room temperature can convert aromatic isothiocyanates and varieties of amines into the corresponding guanidines in good to excellent yields (69 - 95%). This green synthetic process in water can be applied to prepare guanidine at gram-scale quantity. The aqueous micellar medium was also reusable to give relatively the similar reaction yields for at least three cycles. The …

Go to article

Application Of Capillary Electrophoresis For Determination Of Glycosaminoglycans In Biological And Cosmetic Samples, Kanokporn Chindaphan Jan 2018

Application Of Capillary Electrophoresis For Determination Of Glycosaminoglycans In Biological And Cosmetic Samples, Kanokporn Chindaphan

Chulalongkorn University Theses and Dissertations (Chula ETD)

In this research, on-line preconcentration and determination of glycosaminoglycans (GAGs), especially chondroitin sulfate (CS), dermatan sulfate (DS) and hyaluronic acid (HA) using capillary electrophoresis (CE) was developed. Large-volume sample stacking using an electroosmotic flow (EOF) pump (LVSEP) technique was employed for on-line preconcentration and improvement of the detection sensitivity in CE method. Central composite design (CCD) was used to simultaneously optimize all parameters for CE separation. The optimized CE conditions were background electrolyte consisting of 200 mM sodium dihydrogen phosphate, 200 mM buthylamine and 0.5% w/v polyethylene glycol at pH 4.0 and separation voltage of -16 kV. Limit of detections …

Go to article

Electrochemical Detection Of Herbicides And Antioxidants Using Nanomaterial-Modified Electrode, Kanokwan Charoenkitamorn Jan 2018

Electrochemical Detection Of Herbicides And Antioxidants Using Nanomaterial-Modified Electrode, Kanokwan Charoenkitamorn

Chulalongkorn University Theses and Dissertations (Chula ETD)

This dissertation focused on the development of a novel nanomaterial-based electrochemical sensors for pharmaceutical and environmental applications. The research is divided into two parts. In the first part, a low-cost and disposable sensor for the simultaneous determination of coenzyme Q10 (CoQ10) and α-lipoic acid (ALA) using manganese (IV) oxide-modified screen-printed graphene (MnO2/SPGE) electrode was developed. The incorporated MnO2 in the SPGE can greatly enhance the detection performance towards the oxidation of CoQ10 and ALA. The cyclic voltammetry (CV) and square-wave anodic stripping voltammetry (SWASV) were employed to investigate the electrochemical behavior of the developed sensor and also to perform the …

Go to article

Dft And Dftb Investigations On Α–Mangostin Dye Adsorbed On Titanium Dioxide Electrode In Dsscs Application, Kanthira Kaewsud Jan 2018

Dft And Dftb Investigations On Α–Mangostin Dye Adsorbed On Titanium Dioxide Electrode In Dsscs Application, Kanthira Kaewsud

Chulalongkorn University Theses and Dissertations (Chula ETD)

Conformations of α–mangostin dye (1,3,6–Trihydroxy–7–methoxy–2,8–bis(3–methyl–2–buten–1–yl)–9H–xanthen–9–one) were studied and three conformers were found as three co-existing species in various media (in vacuo, acetonitrile and water). Geometries, electronic structures and UV–Vis spectra of all conformers in various media have been obtained using density functional theory (DFT) and time–dependent DFT (TD–DFT) methods. The conformers of α–mangostin dye were inspected as photosensitizers for application in dye sensitized solar cells (DSSCs) and their light–harvesting efficiencies (LHEs) within the range of 0.6757–0.7556 eV (in vacuo), 0.8286–0.8466 eV (in acetonitrile) and 0.8288–0.8465 eV (in water) were obtained. The open circuit voltage (VOC) of three conformers within the …

Go to article

Speciation Of Arsenic Using Sulfur Containing Ligand And Cotton Wool By Icp-Oes, Kavee Triteeyaprasert Jan 2018

Speciation Of Arsenic Using Sulfur Containing Ligand And Cotton Wool By Icp-Oes, Kavee Triteeyaprasert

Chulalongkorn University Theses and Dissertations (Chula ETD)

This research aimed to develop a method for speciation of arsenic species including As(III) and As(V) in environmental samples. Cotton wool and sulfur containing ligands including ammonium pyrrolidinedithiocarbarmate (APDC), L–cysteine and diethyldithiocarbamic acid were used in a solid phase extraction and determination of arsenic by using inductively coupled plasma optical emission spectrometry. The separation parameters were studied including pH, ligand concentration, cotton amount, type of eluents and flow rate. It was found that at pH 2, 0.1% APDC concentration and 0.5 g of cotton, As(III) could form complex with APDC (As(III) – APDC) and was separated from As(V) by using …

Go to article

Green Synthesis Of Gold Nanoparticles Using Wax Leaved Climber Cryptolepis Buchanani Latex And Biological Activities, Kittiphong Tongsuk Jan 2018

Green Synthesis Of Gold Nanoparticles Using Wax Leaved Climber Cryptolepis Buchanani Latex And Biological Activities, Kittiphong Tongsuk

Chulalongkorn University Theses and Dissertations (Chula ETD)

Gold nanoparticles (AuNPs) is the one of nanodrug carriers that have been popular in the current trend. To prepare AuNPs for biomedical applications, many techniques have been developed. However, both physical and chemical methods may cause energy consuming and toxic residues so green synthesis would be the most appropriate method for the preparation of AuNPs. The green synthesis of AuNPs could be provided by utilizing of fungi, bacteria and plant. In this work, we focused to use plant latex as reducing and stabilizing agents for the synthesis of AuNPs. The latex was collected from Cryptolepis buchanani, a folk medicinal plant …

Go to article

First Prev Next Last