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Articles 1861 - 1890 of 2807
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Development Of Stack Model For Tri-Electrode Rechargeable Zinc-Air Cylindrical Flow Battery, Kanya Bumroongsil
Development Of Stack Model For Tri-Electrode Rechargeable Zinc-Air Cylindrical Flow Battery, Kanya Bumroongsil
Chulalongkorn University Theses and Dissertations (Chula ETD)
Nowadays, the demand for renewable energy is continuously increasing. Therefore, an efficient energy storage system is essential. Zinc-air batteries have received extensive attention because they use low-cost material but offer great safety benefits. This research, therefore, develops a stack model for a tri-electrode tubular designed rechargeable zinc-air flow battery for using in a large scale system. The connection of battery cells in series and parallel is studied. The connection of battery cell with common flowing electrolyte creates a shunt current. A mathematical model is developed and validated against experimental data, which measured both full cell and half cell potentials. The …
A Study On The Deactivation Of Nickel-Based Catalyst For The Dry Reforming Of Methane Via Density Functional Theory, Mongkol Lerdpongsiripaisarn
A Study On The Deactivation Of Nickel-Based Catalyst For The Dry Reforming Of Methane Via Density Functional Theory, Mongkol Lerdpongsiripaisarn
Chulalongkorn University Theses and Dissertations (Chula ETD)
In this work, the stability assessment of catalyst for the dry reforming reaction was investigated through the coke resistance performance and the ability of coke removal. The coke resistance performance was considered via the coke adsorption energy. For surface 100 and 211, NiCo bimetallic catalyst and Ni exhibit weaker bonding between coke and catalyst surface. For surface 111, both catalysts exhibited similar adsorption energy value. NiCo bimetallic catalyst also showed higher adsorption energy for surface 111 and 211 than the noble metal catalyst such as Rh and Pd catalyst which means NiCo catalysts can show the coke resistance performance that …
Study Effect Of Catalyst Shape On The Ethylbenzene Dehydrogenation In Fixed Bed Reactor By Using Various Mathematical Models, Pawinee Maithong
Study Effect Of Catalyst Shape On The Ethylbenzene Dehydrogenation In Fixed Bed Reactor By Using Various Mathematical Models, Pawinee Maithong
Chulalongkorn University Theses and Dissertations (Chula ETD)
Nowadays, the chemicals are mostly manufactured by catalytic reactions in fixed bed reactor. Catalyst shape affects to reactor performance and the effect is studied by mathematic models which are varied forms to more realistic. Therefore, the objective of research is to study the effect of catalyst shape on the behavior of reactor for ethylbenzene dehydrogenation to styrene in gas phase by varied form. The simplest model, pseudohomogeneous model (model1), predicts 36.52% ethylbenzene conversion. The more complex model, heterogeneous model accounting for internal mass transfer (model2), predicts 34.49% conversion that equals to the model accounting for internal mass and heat transfer(model3). …
Modeling Production Of Aromatic From N-Paraffins With Chemical Equilibria, Thidarat Detsut
Modeling Production Of Aromatic From N-Paraffins With Chemical Equilibria, Thidarat Detsut
Chulalongkorn University Theses and Dissertations (Chula ETD)
Chemical Equilibrium models were constructed for modeling and developing the aromatic production model from the normal paraffin at the equilibrium of the reaction with catalysts, i.e. ZSM-5(80) and Mo2C. The models were verified under operating temperatures of 450-500 ° C under atmospheric pressure at 1 atm. By examining the accuracy by comparing the data calculated from each model with the value obtained from the corresponding experiments at the condition that the reaction is balanced. The suitable equilibrium model depends on the type of catalyst used in the system. The accuracy of all equilibrium models could be improved by specifying the …
Separation Of Trace Palladium Chloro Complexes From Wastewater Of Electroless Plating Process Via Hollow Fiber Supported Liquid Membrane, Vanee Mohdee
Chulalongkorn University Theses and Dissertations (Chula ETD)
The separation of palladium (Pd (II)) from wastewater containing copper (Cu (II)) and nickel (Ni (II)) is investigated via hollow fiber supported liquid membrane (HFSLM). The viability to separate Pd (II) was established by controlling the influence of operating conditions viz. aqueous feed acidity, carrier concentration, types of stripping solution as well as flows rate of feed and stripping solutions. A complete separation of Pd (II) acheiving >99% extraction and 87.09% recovery was demonstrated under optimum conditions of 6%(v/v) Aliquat 336, pH 2 as aqueous feed acidity, 0.5 M thiourea mixed with 0.1 M HCl as a strippant and 100 …
Molecular Dynamics Simulation Of Phenolic Compound Adsorption On Amine-Functionalized Carbon Nanotubes, Nutapong Tanatananon
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 …
Correlation Of Restitution Coefficient : Experiment And Computational Fluid Dynamics Simulation, Tarabordin Yurata
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 …
Density Functional Theory Study Of Aldol Condensation Between Furfural And 2-Butanone Over Magnesium Oxide, Wilasinee Heebnak
Density Functional Theory Study Of Aldol Condensation Between Furfural And 2-Butanone Over Magnesium Oxide, Wilasinee Heebnak
Chulalongkorn University Theses and Dissertations (Chula ETD)
Understanding of mechanistic and thermodynamic insights of the aldol condensation reaction is crucial to efficient catalytic conversion of biomass-derived oxygenates to fuel-range hydrocarbons. In this study, the aldol condensation of furfural and 2-butanone on magnesium oxide (MgO) catalyst was investigated using density functional theory (DFT) calculations. Energy profiles were computed for elementary steps, including Step 1: Formation of 2-butanone enolate, Step 2: Enolate addition at the carbonyl group of adsorbed furfural, and Step 3: Dehydration to form the condensation product. The DFT results showed that the enolization of 2-butanone was the rate-determining step. The methyl enolate can bind to MgO …
Metallophthalocyanine-Based Electrode For Sodium-Ion Batteries, Apinut Chongphanitkul
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 …
Molecular Dynamics Simulations Of M2 Channel In Phospholipid Bilayers With Different Thickness, Channarong Khrutto
Molecular Dynamics Simulations Of M2 Channel In Phospholipid Bilayers With Different Thickness, Channarong Khrutto
Chulalongkorn University Theses and Dissertations (Chula ETD)
Two previous studies showed that M2 channel, a viral protein plays important role in replication of influenza virus, had different conformation after phospholipid bilayers thickness by using site-directed spin-label EPR spectroscopy (SDSL/EPR), one study, the M2 was spin-labeled on N-terminal amino acid residues, another one the M2 was spin-labeled on the C-terminal amino acid residues. Both studies supported each another. The more thickness phospholipid bilayer is the higher spin coupling value. It can be concluded that the conformation of M2 channel depends on phospholipid bilayer thickness. Data got from this technique is ambiguous, spin-spin coupling cannot be distinguishable, diagonal distance …
Interactions Of Pyrrolidinyl Peptide Nucleic Acid With Oligodeoxyguanosine And Biosensing Applications, Chayan Charoenpakdee
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 …
Non-Hessian Method For Normal Coordinates Calculation, Chirayut Supunyabut
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 …
Chemical Constituents Of Knema Angustifolia Stem And Biological Activities, Dung Le Thi Kim
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 …
Synthesis And Electropolymerization Of Phthalocyanine Derivatives For Electrochemical Reduction Of Carbon Dioxide, Jirapong Luangchaiyaporn
Synthesis And Electropolymerization Of Phthalocyanine Derivatives For Electrochemical Reduction Of Carbon Dioxide, Jirapong Luangchaiyaporn
Chulalongkorn University Theses and Dissertations (Chula ETD)
This research describes synthesis and electrochemical polymerization of novel bithiophenyl-substituted phthalocyanines in order to get polymeric films that have electrocatalytic activities towards reduction of carbon dioxide (CO2). The target phthalocyanine monomers are synthesized by a two-step procedure including Suzuki reaction and cyclization of the resulting phthalonitrile. After that, electropolymerization of the target monomers on an indium tin oxide-coated glasses or carbon papers is performed by a cyclic voltammetry technique. The resulting polymer films are characterized by various spectroscopic methods. Catalytic performance towards the electrochemical reduction of CO2 of these polymers is investigated by the cyclic voltammetry and controlled potential electrolysis …
Synthesis And Development Of Nanocomposites Of Magnetic Nanoparticles-Silica-Mannan As Vaccine Adjuvants, Kamonlatth Rodponthukwaji
Synthesis And Development Of Nanocomposites Of Magnetic Nanoparticles-Silica-Mannan As Vaccine Adjuvants, Kamonlatth Rodponthukwaji
Chulalongkorn University Theses and Dissertations (Chula ETD)
Over the past years, vaccination has been considered as an effective treatment against a wide range of pathogens and diseases. Despite a promising outcome, the lack of strong immune response of some types of vaccines is still challenging. Therefore, targeting and activating dendritic cells (DCs) using nanomaterial-based vaccine adjuvant is of our interest. Herein, superparamagnetic iron oxide nanoparticles (SPIONs) have been exploited as directing agents to the targeted dendritic cells (DCs). In addition, mannan extracted from Saccharomyces cerevisiae was used as targeting molecules for targeting DCs. Nanocomposites of silica-magnetic nanoparticles-mannan (S-SPION-MN) were successfully fabricated. The synthesized particles were morphologically and …
Thread Based Wearable Electrochemical Sensor For Uric Acid Detection, Kanyapat Teekayupak
Thread Based Wearable Electrochemical Sensor For Uric Acid Detection, Kanyapat Teekayupak
Chulalongkorn University Theses and Dissertations (Chula ETD)
Novel cotton thread-based electrochemical sensor was successfully fabricated for a non-invasive and non-enzymatic detection of uric acid (UA), a biomarker of gout disease. In this work, the working electrode was prepared by coating a carbon ink on the cotton thread to create the conductive property, followed by electrode modification using gold nanoparticles (AuNPs) to increase electrode surface area and conductivity. The morphologies of the modified electrode were characterized by scanning electron microscopy (SEM) with energy dispersive X-rays spectroscopy (EDX), confirming that AuNPs were modified on the electrode surface and the surface area of the modified electrode increased. The electrochemical characteristics …
Development Of Portable Electrochemical Sensors For Determination Of Heavy Metals, Nitrogen Oxides And Thiocyanate Ion, Kingkan Pungjunun
Development Of Portable Electrochemical Sensors For Determination Of Heavy Metals, Nitrogen Oxides And Thiocyanate Ion, Kingkan Pungjunun
Chulalongkorn University Theses and Dissertations (Chula ETD)
This dissertation focused on the development of portable electrochemical sensors using the paper-based analytical device (ePAD) for the determination of the important compounds/biomarkers in various applications. Considering the target applications, this dissertation can be divided into three main parts including food safety application, environmental analysis and clinical application, respectively. In the first part, two sub-sections relating to the detection of heavy metals contaminated in food will be discussed. For the first sub-section, an ePAD coupled with a boron-doped diamond electrode was developed for the determination of total arsenic. The device was performed using the origami paper device for the preparation …
Synthesis Of Chalcone Derivatives As Ampk Activators, Duy Vu Nguyen
Synthesis Of Chalcone Derivatives As Ampk Activators, Duy Vu Nguyen
Chulalongkorn University Theses and Dissertations (Chula ETD)
Diabetes and diabetic nephropathy are two noticeable disorders in modern life. Chalcones are considered as a feasible candidate for these medication disorders due to the capability to activate AMPK relating to these two diseases. A series of chalcones with A-ring possessing 2'-hydroxy-, 3',4',5'-trimethoxyacetophenones or other types and B-ring decorated with mono-, di-, trisubstitution were accomplished by Claisen–Schmidt, etherification and hydrogenation reactions in almost moderate to high yield. 3-Methoxy group was found to be the best substituent for the activity in case of monosubstitution on B-ring. 3,4-Dimethoxy and 3,4-methylenedioxy groups on B-ring (63 and 65) enhanced the activity of disubstituted chalcones …
Development Of Sensing Platforms Using Bulk Optode Technique For Detection Of Silver And Mercury Ions, Manoon Phichi
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 …
Bioactive Compounds From Lichen Usnea Baileyi (Stirt.) Zahlbr. And Usnic Acid Derivatives, Kieu Van Nguyen
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 …
Paper-Based Arrays For Geographical Indication Of Turmerics, Monrawat Rauytanapanit
Paper-Based Arrays For Geographical Indication Of Turmerics, Monrawat Rauytanapanit
Chulalongkorn University Theses and Dissertations (Chula ETD)
Geographical indications have gained increasing importance as a powerful marketing tool for highly valuable products especially foods. In this study, a synergistic combination of chemical reaction arrays on paper and chemometric analysis was used to uncover geographical indication of turmerics, an important food ingredient in several Asian cuisines. The key to effective differentiation was from the subtle differences in the compositions of the compounds found in turmeric samples, mainly curcumin and derivatives which were preliminarily confirmed by HPLC and LC-MS experiments. In addition, the differences in the major and minor components affect the reactivity and the pattern of obtained products …
Chemical Constituents From The Stems Of Garcinia Cylindrocarpa And The Stem Bark Of Garcinia Picrorhiza And Garcinia Tetrandra, Edwin Risky Sukandar
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 …
Visualization Of Vibrational Spectra Based On Expanded Moment Of Inertia Tensor, Napat Sitthimonchai
Visualization Of Vibrational Spectra Based On Expanded Moment Of Inertia Tensor, Napat Sitthimonchai
Chulalongkorn University Theses and Dissertations (Chula ETD)
Expanded Moment of Inertia Tensor (EMIT) is a non-Hessian-based method to evaluate a set of the normal coordinates, utilizing to calculate vibrational spectra from the molecular dynamics simulation data. Unlike the traditional moment of inertia tensor, the EMIT method constructs an atomic moment of inertia tensor situated on an individual atom in the molecule. Unfortunately, the results obtained from EMITare too complicated to visualize by naked eyes, a user-friendly visualization program is needed. In this work, we have developed a program called “EMIT Studio”, written in C++ and OpenGL Library, to visualize atomic displacement vectors, molecular normal modes, and vibrational …
Development Of Biosensor Using Pyrrolidinyl Pna For Screening Of Hepatitis C Virus Dna, Narathorn Nisab
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, …
Preparation Of Calcium Citrate Based Vitamin B₁₂/Cisplatin Nanocomposite As Novel Targeted Drug Carrier, Natchanon Rimsueb
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 …
Chemical Constituents And Antibacterial Activity Of Rhizomes From Globba Schomburgkii Hook.F., Naruemon Suekaew
Chemical Constituents And Antibacterial Activity Of Rhizomes From Globba Schomburgkii Hook.F., Naruemon Suekaew
Chulalongkorn University Theses and Dissertations (Chula ETD)
Globba schomburgkii Hook.f. rhizomes were extracted with dichloromethane and fractionated using column chromatography to obtain 10 fractions (FA-FJ). The most active fractions, FE and FG, were further fractionated to give seven and thirteen sub-fractions, respectively. The fractions and sub-fractions were tested for antibacterial activity using 96-well plate microdilution method. The antibacterial activity of several sub-fractions (such as FE.B, FE.C, FE.D, FG.D, FG.G, and FG.H) were higher than that of the crude extract. Chemical compositions of all fractions and sub-fractions were analyzed by gas chromatography hyphenated with mass spectrometry (GC-MS), revealing 167 compounds identified according to match between the experimental MS …
Development Of Thin-Layer Chromatography For Selective Analysis Of Volatile Compounds Using Gas Chromatography Mass Spectrometry, Nattapat Suchatanugal
Development Of Thin-Layer Chromatography For Selective Analysis Of Volatile Compounds Using Gas Chromatography Mass Spectrometry, Nattapat Suchatanugal
Chulalongkorn University Theses and Dissertations (Chula ETD)
In this study, simple and selective solid phase extraction approach for a range of volatile compounds in perfume was developed prior to analysis with headspace solid phase micro extraction (HS-SPME) and gas chromatography hyphenated with mass spectrometry (GC-MS). The technique relies on use of thin layer chromatography (TLC) for separation of compound along the silica gel plate followed by selective cuts of the regions of interest, desorption, HS-SPME and GC-MS analysis. The TLC separation of standard compounds using hexane and ethyl acetate (6:1 volume ratio) as the mobile phase was initially performed. The compounds was then desorbed from the TLC …
Chemometric Method To Enhance Sensitivity And Selectivity For Surface Enhanced Raman Scattering Technique, Nontawat Sricharoen
Chemometric Method To Enhance Sensitivity And Selectivity For Surface Enhanced Raman Scattering Technique, Nontawat Sricharoen
Chulalongkorn University Theses and Dissertations (Chula ETD)
The multivariate curve resolution-alternative least square (MCR-ALS) algorithm was modified with sample insertion constraint. This developed method was proposedly used to deconvolute the overlapping signals in Surface enhance Raman attering (SERS) measurement. The developed method was elucidated with the spectral data simulated by using Gaussian distribution function to generate two independent peaks which correspond to capping agent and analyte, respectively. The spectrum of the two peaks was generated with different overlapping levels (RS = 0 – 1.50) and concentration ratio of analyte and capping agent concentration at 0.01 – 1.00. In MCR-ALS with sample insertion constraint, the number of capping …
Structure And Hydration Property Of Low Molecular Weight Hyaluronic Acid By Molecular Dynamics Simulations, Panyakorn Taweechat
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 …
Flexible Sers Substrate Fabricated From Gold Nanostar, Piboonwan Insiti
Flexible Sers Substrate Fabricated From Gold Nanostar, Piboonwan Insiti
Chulalongkorn University Theses and Dissertations (Chula ETD)
In this work, a one-pot protocol for the fabrication of surface-enhanced Raman scattering (SERS) substrate has been developed. It consists of quasi-spherical gold nanoparticles (AuQNPs) uniformly which is deposited on a disk paper substrate (5-mm in diameter). The disk of filter paper surface was coated by bacterial cellulose nanocrystal (BCNC). The BCNC smoothed the surface by forming thin nanopaper film upon drying while filling the gap between fibers. AuQNPs was directly synthesized on the surface of BCNC film via seed-growth method. The BCNC film with abundant hydroxyl groups became anchor points for AuNPs which help to create uniform distribution of …