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

Chemistry Commons™

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

2020

Discipline
Institution
Keyword
Publication
Publication Type
File Type

Articles 1351 - 1380 of 1559

Full-Text Articles in Chemistry

Polyacrylamide In Glycerol Solutions From An Atomistic Perspective Of The Energetics, Structure, And Dynamics, Scott D. Hopkins, Gideon K. Gogovi, Eric Weisel, Robert A. Handler, Estela Blaisten-Barojas Jan 2020

Polyacrylamide In Glycerol Solutions From An Atomistic Perspective Of The Energetics, Structure, And Dynamics, Scott D. Hopkins, Gideon K. Gogovi, Eric Weisel, Robert A. Handler, Estela Blaisten-Barojas

VMASC Publications

All-atom molecular dynamics is used to investigate the structural, energetic, and dynamical properties of polyacrylamide (PAM) oligomers of different lengths solvated in pure glycerol, a 90:10 glycerol–water mixture, and pure water. We predict that the oligomers’ globular structure is obtained only when the modeling strategy considers the solvent as a continuous background. Meanwhile, for all-atom modeled solvents, the glycerol solutions display a strong tendency of trapping the oligomers in instantaneous elongated random coiled structures that remain locked-in over tens of nanoseconds. In pure water, the oligomers acquire considerably shorter random coiled structures of increased flexibility. The all-atom force field, generalized …

Go to article

Effect Of The Electrodeposition Potential Of Platinum On The Catalytic Activity Of A Pt/Gc Catalyst Toward Formic Acid Electro−Oxidation, Islam M. Al-Akraa, Bilquis A. Al-Qodami Ms., Ahmad M. Mohammad Prof Jan 2020

Effect Of The Electrodeposition Potential Of Platinum On The Catalytic Activity Of A Pt/Gc Catalyst Toward Formic Acid Electro−Oxidation, Islam M. Al-Akraa, Bilquis A. Al-Qodami Ms., Ahmad M. Mohammad Prof

Chemical Engineering

The electrocatalytic activity of platinum (Pt)–modified glassy carbon (GC) (referred as Pt/GC) electrodes toward the formic acid electro−oxidation (FAO) was investigated. The Pt deposition on the GC substrate was carried out by a potentiostatic technique at different potentials (from 0.2 V to −0.2 V vs. Hg/Hg2Cl2/KCl (sat.) reference electrode) and the corresponding influence on the catalytic activity toward FAO was monitored. The electrocatalytic inspection revealed a potential role for the Pt deposition potential in boosting the catalytic efficiency of the catalyst toward FAO and further in mitigating the CO poisoning that eventually deactivate the catalyst. Interestingly, the highest activity toward …

Go to article

A Spin-Coated Tiox/Pt Nanolayered Anodic Catalyst For The Direct Formic Acid Fuel Cells, Islam M. Al-Akraa, Ahmad M. Mohammad Prof Jan 2020

A Spin-Coated Tiox/Pt Nanolayered Anodic Catalyst For The Direct Formic Acid Fuel Cells, Islam M. Al-Akraa, Ahmad M. Mohammad Prof

Chemical Engineering

The CO poisoning of the platinum anodic catalyst which typically functions the catalytic deterioration of the direct formic acid fuel cells could be minimized with a simple modification for Pt with titanium oxide. The fabrication scheme involved the spin-coating of a Ti precursor onto a Pt thin layer that was physically sputtered onto a Si substrate. The whole assembly was subjected to a post-annealing processing to produce the TiOx layer (60 nm) in a porous structure (mostly Anatase) atop of the Pt surface. The porous nature of the TiOx layer permitted the participation of Pt in the electrocatalysis of the …

Go to article

Resolving The Puzzle Of Single-Atom Silver Dispersion On Nanosized Γ-Al2O3 Surface For High Catalytic Performance, Fei Wang, Jinzhu Ma, Shaohui Xin, Qiang Wang, Jun Xu, Changbin Zhang, Hong He, Xiao Cheng Zeng Jan 2020

Resolving The Puzzle Of Single-Atom Silver Dispersion On Nanosized Γ-Al2O3 Surface For High Catalytic Performance, Fei Wang, Jinzhu Ma, Shaohui Xin, Qiang Wang, Jun Xu, Changbin Zhang, Hong He, Xiao Cheng Zeng

Xiao Cheng Zeng Publications

Ag/γ-Al2O3 is widely used for catalyzing various reactions, and its performance depends on the valence state, morphology and dispersion of Ag species. However, detailed anchoring mechanism of Ag species on γ-Al2O3 remains largely unknown. Herein, we reveal that the terminal hydroxyls on γ-Al2O3 are responsible for anchoring Ag species. The abundant terminal hydroxyls existed on nanosized γ-Al2O3 can lead to single-atom silver dispersion, thereby resulting in markedly enhanced performance than the Ag cluster on microsized γ-Al2O3. Density-functional-theory calculations confirm that Ag atom is mainly …

Go to article

Development Of A Novel Highly-Sensitive Brucellosis Sensor Based On Surface Plasmon Resonance Spectroscopy, Amal Kasry, Ihab Adly, Asharf Sayour, Hossam Sayour Jan 2020

Development Of A Novel Highly-Sensitive Brucellosis Sensor Based On Surface Plasmon Resonance Spectroscopy, Amal Kasry, Ihab Adly, Asharf Sayour, Hossam Sayour

Nanotechnology Research Centre

Brucellosis is considered a significant health threat, it is an infectious disease caused by the bacteria Brucella, which can spread from animals to humans causing severe diseases. Through this project, we aim to develop a very highly sensitive biosensor to detect Brucella early before spreading. This sensor is based on surface plasmon resonance (SPR) technique, which is used to analyze kinetics of interaction between biomolecules. It can detect down to picomolar concentrations of some proteins.

Go to article

Synthesis, Magnetic And Adsorption Of Dye Onto The Surface Of Nio Nanoparticles, Islam Gomaa, Nasser M. Hosny Jan 2020

Synthesis, Magnetic And Adsorption Of Dye Onto The Surface Of Nio Nanoparticles, Islam Gomaa, Nasser M. Hosny

Nanotechnology Research Centre

NiO was synthesized simply via thermal decomposition of nickel ascorbate, which resulted from semi-solid reaction of nickel acetate and ascorbic acid. The prepared precursor was characterized by elemental, thermal and spectral analyses. The precursor was decomposed at 700 °C producing cubic NiO with average size 50 nm as indicated from XRD and TEM. FESEM indicated the formation of macroporous NiO. Magnetic parameters (saturation magnetization (Ms), remanence (Mr) and coercivity (Hc)) of NiO nanoparticles and its precursor were determined and compared with the bulk nickel. Zeta potential measurements at different pH values indicated that NiO is negatively charged. Adsorption of ponceau …

Go to article

Semiempirical Molecular Modeling Analyses For Graphene/Nickel Oxide Nanocomposite, Islam Gomaa, Medhat A. Ibrahim, Hanan Elhaes Jan 2020

Semiempirical Molecular Modeling Analyses For Graphene/Nickel Oxide Nanocomposite, Islam Gomaa, Medhat A. Ibrahim, Hanan Elhaes

Nanotechnology Research Centre

Graphene metal oxide composite show applications in many areas according to their excellent electronic properties. Accordingly, graphene was subjected to interaction with NiO as adsorbing and a complex state. Semiempirical quantum mechanical calculations at PM6 was used to study the total energy, the final heat of formation, ionization energy, total dipole moment as well the charge distribution of the surface of graphene metal oxide composite. Calculated data indicated that graphene symmetry is changed into the C1 point group, forming stable composites with NiO that the complex composites were more stable compared with adsorb state composites. The change in the partial …

Go to article

Carbon Oxidation State In Microbial Polar Lipids Suggests Adaptation To Hot Spring Temperature And Redox Gradients, Grayson M. Boyer, Florence Schubotz, Roger E. Summons, Jade Woods, Everett L. Shock Jan 2020

Carbon Oxidation State In Microbial Polar Lipids Suggests Adaptation To Hot Spring Temperature And Redox Gradients, Grayson M. Boyer, Florence Schubotz, Roger E. Summons, Jade Woods, Everett L. Shock

Department of Chemistry: Faculty Publications

The influence of oxidation-reduction (redox) potential on the expression of biomolecules is a topic of ongoing exploration in geobiology. In this study, we investigate the novel possibility that structures and compositions of lipids produced by microbial communities are sensitive to environmental redox conditions. We extracted lipids from microbial biomass collected along the thermal and redox gradients of four alkaline hot springs in Yellowstone National Park (YNP) and investigated patterns in the average oxidation state of carbon (ZC), a metric calculated from the chemical formulae of lipid structures. Carbon in intact polar lipids (IPLs) and their alkyl chains becomes …

Go to article

Surface Modification Of Silicon Nanowire Based Field Effect Transistors With Stimuli Responsive Polymer Brushes For Biosensing Applications, Stephanie Klinghammer, Sebastian Rauch, Sebastian Pregl, Petra Uhlmann, Larysa Baraban, Gianaurelio Cuniberti Jan 2020

Surface Modification Of Silicon Nanowire Based Field Effect Transistors With Stimuli Responsive Polymer Brushes For Biosensing Applications, Stephanie Klinghammer, Sebastian Rauch, Sebastian Pregl, Petra Uhlmann, Larysa Baraban, Gianaurelio Cuniberti

Department of Chemistry: Faculty Publications

We demonstrate the functionalization of silicon nanowire based field effect transistors (SiNW FETs) FETs with stimuli-responsive polymer brushes of poly(N-isopropylacrylamide) (PNIPAAM) and poly(acrylic acid) (PAA). Surface functionalization was confirmed by atomic force microscopy, contact angle measurements, and verified electrically using a silicon nanowire based field effect transistor sensor device. For thermo-responsive PNIPAAM, the physicochemical properties (i.e., a reversible phase transition, wettability) were induced by crossing the lower critical solution temperature (LCST) of about 32 ◦C. Taking advantage of this property, osteosarcomic SaoS-2 cells were cultured on PNIPAAM-modified sensors at temperatures above the LCST, and completely detached by simply cooling. Next, …

Go to article

Rapid And Accurate Determination Of Atomistic Rna Dynamic Ensemble Models Using Nmr And Structure Prediction, Honglue Shi, Atul Rangadurai, Hala Abou Assi, Rohit Roy, David A. Case, Daniel Herschlag, Joseph D. Yesselman, Hashim M. Al-Hashimi Jan 2020

Rapid And Accurate Determination Of Atomistic Rna Dynamic Ensemble Models Using Nmr And Structure Prediction, Honglue Shi, Atul Rangadurai, Hala Abou Assi, Rohit Roy, David A. Case, Daniel Herschlag, Joseph D. Yesselman, Hashim M. Al-Hashimi

Department of Chemistry: Faculty Publications

Biomolecules form dynamic ensembles of many inter-converting conformations which are key for understanding how they fold and function. However, determining ensembles is challenging because the information required to specify atomic structures for thousands of conformations far exceeds that of experimental measurements. We addressed this data gap and dramatically simplified and accelerated RNA ensemble determination by using structure prediction tools that leverage the growing database of RNA structures to generate a con- formation library. Refinement of this library with NMR residual dipolar couplings provided an atomistic ensemble model for HIV-1 TAR, and the model accuracy was independently sup- ported by comparisons …

Go to article

A Luminescence-Based System For Identification Of Genetically Encodable Inhibitors Of Protein Aggregation, Travis J. Nelson, Shuo Liang, Cliff I. Stains Jan 2020

A Luminescence-Based System For Identification Of Genetically Encodable Inhibitors Of Protein Aggregation, Travis J. Nelson, Shuo Liang, Cliff I. Stains

Department of Chemistry: Faculty Publications

Molecules that disrupt protein aggregation represent potential tool compounds for the investigation of numerous human disease states. However, the identification of small molecules capable of disrupting protein aggregation has proven challenging. Larger biomolecules such as antibodies and proteins are promising alternatives due to their increased size. Despite the promise of protein-based inhibitors, generalizable assays are needed to more readily identify proteins capable of inhibiting aggregation. Herein, we utilize our previously reported self- assembling NanoLuc luciferase fragments to engineer a platform in which both detection reagents are expressed from the same plasmid, enabling facile co-transformation with a genetically encodable inhibitor. This …

Go to article

Constructing Stable And Potentially High-Performance Hybrid Organic-Inorganic Perovskites With “Unstable” Cations, Qing Yang, Menghao Wu, Xiao Cheng Zeng Jan 2020

Constructing Stable And Potentially High-Performance Hybrid Organic-Inorganic Perovskites With “Unstable” Cations, Qing Yang, Menghao Wu, Xiao Cheng Zeng

Department of Chemistry: Faculty Publications

A new family of functional hybrid organic-inorganic perovskites (HOIPs) is theoretically designed based on the following chemical+ insights: when a proton is adhered to molecules like water or ethanol, the newly formed larger-sized cations (e.g., H5O2 ,++ C2H5OH2 , and CH3SH ) entail low electron affinities mimicking superalkalis; they are conjugated acids of weak bases that cannot survive in solution, while their chemistry behavior in the HOIP frameworks, however, may be markedly different due to greatly enhanced cohesive energies of the proton, which facilitate the formation of new HOIPs. First-principles computations show that the putative formation reactions for these newly …

Go to article

Domain Wall Conduction In Calcium-Modified Lead Titanate For Polarization Tunable Photovoltaic Devices, Chong-Xin Qian, Hong-Jian Hong-Jian, Qiang Zhang, Jiawei He, Zi-Xuan Chen, Ming-Zi Wang, Xiao Cheng Zeng Jan 2020

Domain Wall Conduction In Calcium-Modified Lead Titanate For Polarization Tunable Photovoltaic Devices, Chong-Xin Qian, Hong-Jian Hong-Jian, Qiang Zhang, Jiawei He, Zi-Xuan Chen, Ming-Zi Wang, Xiao Cheng Zeng

Department of Chemistry: Faculty Publications

Ferroelectric domain wall (DW) conduction, confirmed in recent experiments, has attracted intense attention due to its promising applications in optoelec- tronic devices. Herein, we provide theoretical evidence of electric conduction in Pb0.8Ca0.2TiO3 (PCT) DWs. The separation of charge accumulation in DWs, corresponding to the electronic conduction-band minimum (CBM) and valence-band maximum (VBM), weakens the tendency for the electron-hole recombination, thereby providing more efficient channels for charge transfer. We fabricate PCT-based functional photovoltaic devices with polarization tunable charge transfer to exploit the combined conduction and ferroelectric properties of the DW. The photovoltaic performance of the devices can be regu- lated by …

Go to article

Mechanistic Insights Into The Acetate-Accelerated Synthesis Of Crystalline Ceria Nanoparticles, Tamra J Fisher, Deepa Choudhry, Kaitlynn Derr, Soodabeh Azadehranjbar, Dan Stasko, Chin Li Cheung Jan 2020

Mechanistic Insights Into The Acetate-Accelerated Synthesis Of Crystalline Ceria Nanoparticles, Tamra J Fisher, Deepa Choudhry, Kaitlynn Derr, Soodabeh Azadehranjbar, Dan Stasko, Chin Li Cheung

Department of Chemistry: Faculty Publications

Recent increasing uses of ceria in research and industrial applications have fostered continuing developments of efficient routes to synthesize the material. Here we report our investigation of the effects and the mechanistic roles of lithium acetate to accelerate the growth of crystalline ceria nanoparticles in ozone-mediated synthesis. By increasing the mole ratio of the acetate to cerium nitrate in the reactions, the reaction yields of ceria nanoparticles were observed to increase from ca. 10% to up to over 90% by cerium content in 30 min reactions. Microscopy images and Raman spectra of the assynthesized nanoparticles revealed that increasing the acetate …

Go to article

A Click-Based Modular Approach To Introduction Of Peroxides Onto Molecules And Nanostructures, Alissa Horn, Patrick H. Dussault Jan 2020

A Click-Based Modular Approach To Introduction Of Peroxides Onto Molecules And Nanostructures, Alissa Horn, Patrick H. Dussault

Department of Chemistry: Faculty Publications

Copper-promoted azide/alkyne cycloadditions (CuAAC) are explored as a tool for modular introduction of peroxides onto molecules and nanomaterials. Dialkyl peroxide-substituted alkynes undergo Cu(I)- promoted reaction with azides in either organic or biphasic media to furnish peroxide-substituted 1,2,3- triazoles. Heterolytic fragmentation of the peroxide to an aldehyde, a side reaction that appears to be related to the formation of the triazole, can be suppressed by use of excess alkyne, the presence of triethylsilane, or by use of iodoalkyne substrates. Complementary reactions of simple alkynes with azidosubstituted peroxides are much less efficient. Click reactions of alkynyl peroxyacetals are also reported; reductive fragmentation …

Go to article

Agbis2 As A Low-Cost And Eco-Friendly All-Inorganic Photovoltaic Material: Nanoscale Morphology– Property Relationship†, Ming-Gang Ju, Jun Dai, Liang Ma, Yuanyuan Zhou, Xiao Cheng Zeng Jan 2020

Agbis2 As A Low-Cost And Eco-Friendly All-Inorganic Photovoltaic Material: Nanoscale Morphology– Property Relationship†, Ming-Gang Ju, Jun Dai, Liang Ma, Yuanyuan Zhou, Xiao Cheng Zeng

Department of Chemistry: Faculty Publications

Solar cells made of low-cost solution-processed all-inorganic materials are a promising alternative to conventional solar cells made of high-temperature processed inorganic materials, especially because many high-temperature processed inorganic materials contain toxic element(s) such as lead or cadmium (e.g., CsPbI3 perovskite, PbS, CdTe and CdS(Se)). AgBiS2 nanocrystals, consisting of earth-abundant elements but without lead and cadmium, have already emerged as a promising candidate in highperformance solar cells. However, the nanoscale morphology–optoelectronic property relationship for AgBiS2 nanocrystals is still largely unknown. Herein, we investigate the electronic properties of various AgBiS2 nanocrystals by using first-principles computation. We show that …

Go to article

Letetr Positively Regulates 3-Hydroxylation Of The Antifungal Hsaf And Its Analogs In Lysobacter Enzymogenes Oh11, Lingjun Yu, Vimmy Khetrapal, Fengquan Liu, Liangcheng Du Jan 2020

Letetr Positively Regulates 3-Hydroxylation Of The Antifungal Hsaf And Its Analogs In Lysobacter Enzymogenes Oh11, Lingjun Yu, Vimmy Khetrapal, Fengquan Liu, Liangcheng Du

Liangcheng Du Publications

The biocontrol agent Lysobacter enzymogenes OH11 produces several structurally distinct antibiotic compounds, including the antifungal HSAF (Heat Stable Antifungal Factor) and alteramides, along with their 3-dehydroxyl precursors (3-deOH). We previously showed that the 3-hydroxylation is the final step of the biosynthesis and is also a key structural moiety for the antifungal activity. However, the procedure through which OH11 regulates the 3-hydroxylation is still not clear. In OH11, the gene orf3232 was predicted to encode a TetR regulator (LeTetR) with unknown function. Here, we deleted orf3232 and found that the LeTetR mutant produced very little HSAF and alteramides, while the 3-deOH …

Go to article

Development Of An On-Line Immunoextraction/Entrapment System For Protein Capture And Use In Drug Binding Studies By High-Performance Affinity Chromatography, Elliott L. Rodriguez, Saumen Poddar, Meera Choksi, David S. Hage Jan 2020

Development Of An On-Line Immunoextraction/Entrapment System For Protein Capture And Use In Drug Binding Studies By High-Performance Affinity Chromatography, Elliott L. Rodriguez, Saumen Poddar, Meera Choksi, David S. Hage

David Hage Publications

An on-line purification and entrapment system was developed that could extract a protein from a sample such as serum and entrap this protein within a small column for use in high-performance affinity chromatography. Human serum albumin (HSA) was employed as a model protein for this work. Immunoextraction columns containing polyclonal anti-HSA antibodies were developed to capture and isolate HSA from applied samples. This was followed by the use of a strong cation-exchange column to recapture and focus HSA as it eluted from the immunoextraction columns. The recaptured HSA was entrapped within 1.0 cm × 2.1 mm I.D. columns containing hydrazide-activated …

Go to article

Ionic Liquid Functionalized Β-Cyclodextrin Modified Electrode As Electrochemical Sensor For 2,4-Dichlorophenol, Fairuz Liyana Mohd Rasdi Jan 2020

Ionic Liquid Functionalized Β-Cyclodextrin Modified Electrode As Electrochemical Sensor For 2,4-Dichlorophenol, Fairuz Liyana Mohd Rasdi

Student Works (2020-2029)

This thesis described the synthesis and characterization of ionic liquid monofunctionalized β-cyclodextrin (β-CD-1-BIMOTs) and ionic liquid difunctionalized β-cyclodextrin (β-CD-2-BIMOTs) for sensor applications. The physical characterizations of these compounds have been conducted using nuclear magnetic resonance (NMR), Fourier transform infra-red (FTIR), energy dispersive x-ray (EDX), x-ray diffraction (XRD) and Brunauer-Emmet-Teller (BET) analyses. These compounds were used as modifiers for carbon paste electrode (CPE). Cyclic voltammetry and chrono-amperometry methods were employed to examine the electrochemical responses of all prepared CPEs. All prepared electrodes show responses towards the target analyte of 2,4-dichlorophenol (2,4-DCP). Both β-CD-1-BIMOTs/CPE and β-CD-2-BIMOTs/CPE give higher current (i) responses compared …

Go to article

Boron Trifluoride Etherate Promoted Microwave Assisted Synthesis Of Antimalarial Acridones, Papireddy Kancharla, Rozalia A. Dodean, Yuexin Li, Jane X. Kelly Jan 2020

Boron Trifluoride Etherate Promoted Microwave Assisted Synthesis Of Antimalarial Acridones, Papireddy Kancharla, Rozalia A. Dodean, Yuexin Li, Jane X. Kelly

Chemistry Faculty Publications and Presentations

A microwave-assisted, rapid and efficient method using boron trifluoride etherate (BF3.Et2O) for the synthesis of acridones, via an intramolecular acylation of N-phenylanthranilic acid derivatives, has been developed. The reaction proceeds under solvent-free conditions, tolerates a wide range of functional groups, and provides rapid access to a range of acridones in good to excellent yields. Several of the synthesized acridones exhibited potent antimalarial activities against CQ sensitive and multi-drug resistant (MDR) parasites.

Go to article

Synthesis Of Radioluminescent Caf2:Ln Core, Mesoporous Silica Shell Nanoparticles For Use In X-Ray Based Theranostics, Hayden Winter, Megan J. Neufeld, Lydia Makotamo, Conroy Sun, Andrea M. Goforth Jan 2020

Synthesis Of Radioluminescent Caf2:Ln Core, Mesoporous Silica Shell Nanoparticles For Use In X-Ray Based Theranostics, Hayden Winter, Megan J. Neufeld, Lydia Makotamo, Conroy Sun, Andrea M. Goforth

Chemistry Faculty Publications and Presentations

X-ray radiotherapy is a common method of treating cancerous tumors or other malignant lesions. The side effects of this treatment, however, can be deleterious to patient quality of life if critical tissues are affected. To potentially lower the effective doses of radiation and negative side-effects, new classes of nanoparticles are being developed to enhance reactive oxygen species production during irradiation. This report presents the synthesis and radiotherapeutic efficacy evaluation of a new nanoparticle formulation designed for this purpose, composed of a CaF2 core, mesoporous silica shell, and polyethylene glycol coating. The construct was additionally doped with Tb and Eu …

Go to article

Size-Dependent Interactions Of Lipid-Coated Gold Nanoparticles: Developing A Better Mechanistic Understanding Through Model Cell Membranes And In Vivo Toxicity, Arek M. Engstrom, Ryan A. Faase, Joe E. Baio, Marilyn R. Mackiewicz, Stacey L. Harper Jan 2020

Size-Dependent Interactions Of Lipid-Coated Gold Nanoparticles: Developing A Better Mechanistic Understanding Through Model Cell Membranes And In Vivo Toxicity, Arek M. Engstrom, Ryan A. Faase, Joe E. Baio, Marilyn R. Mackiewicz, Stacey L. Harper

Chemistry Faculty Publications and Presentations

Introduction: Humans are intentionally exposed to gold nanoparticles (AuNPs) where they are used in variety of biomedical applications as imaging and drug delivery agents as well as diagnostic and therapeutic agents currently in clinic and in a variety of upcoming clinical trials. Consequently, it is critical that we gain a better understanding of how physiochemical properties such as size, shape, and surface chemistry drive cellular uptake and AuNP toxicity in vivo. Understanding and being able to manipulate these physiochemical properties will allow for the production of safer and more efficacious use of AuNPs in biomedical applications.
Methods and Materials: Here, …

Go to article

Simple Headspace Device For Determination Of Volatile Compounds In Food And Drug Samples, Kamonwan Meesuwan Jan 2020

Simple Headspace Device For Determination Of Volatile Compounds In Food And Drug Samples, Kamonwan Meesuwan

Chulalongkorn University Theses and Dissertations (Chula ETD)

This work presented a simple alternative method for simultaneous extraction and determination of volatile compounds in complex matrix samples by combining headspace technique with paper based colorimetric method. The paper loaded with colorimetric reagent that was attached to the liner of the vial cap making a simple headspace device for direct detection of the semi-volatile and volatile compounds in headspace extraction mode. A sample was placed in a vial sealed with the paper-based headspace device. The method was tested for determination of volatile compound using ethanol as a model and semi-volatile compound using iodine as a model in complex matrix …

Go to article

Catalytic Conversion Of Chitin To Lactic Acid In Hot-Compressed Water, Kodchakon Kun-Asa Jan 2020

Catalytic Conversion Of Chitin To Lactic Acid In Hot-Compressed Water, Kodchakon Kun-Asa

Chulalongkorn University Theses and Dissertations (Chula ETD)

Chitin is the second most available polysaccharide after cellulose. Chitin and N-acetyl-D-glucosamine polysaccharide, can be converted to valuable products by using homogeneous catalysis, most of the chitin generated by food processing is treated as industrial waste. For chitin conversion to useful chemicals has been investigated less than cellulose conversion. Therefore, in this research, chitin conversion was investigated. The result was divided into four part. The first part, the result showed that ball milled pretreatment could increase the conversion of chitin, which indicated that the crystallinity of the chitin had been reduced by the ball milled pretreatment. In the second part, …

Go to article

Production Of Bio-Jet Fuel From Palm Fatty Acid Distillate Over Teos-Modified Nipd/Zsm-5 Catalysts, Umbon Boonsard Jan 2020

Production Of Bio-Jet Fuel From Palm Fatty Acid Distillate Over Teos-Modified Nipd/Zsm-5 Catalysts, Umbon Boonsard

Chulalongkorn University Theses and Dissertations (Chula ETD)

Jet fuels are mainly derived from the refining of petroleum feedstock which has a negative impact to the environment as it emits greenhouse gases (GHG). Therefore, the development of an alternative and renewable jet fuel is an imminent concern of the aviation industry. One of the alternative jet fuel feedstocks is palm fatty acid distillate (PFAD) due to its relatively low cost. Bio-jet fuel can be produced via three reactions including deoxygenation, isomerization, and cracking. In this study, the bimetallic NiPd supported on ZSM-5 with various Si/Al ratios (23, 50, and 280) and modified ZSM-5 by TEOS were characterized by …

Go to article

Structure And Morphology Of Magnesium Channel By Coarse-Grained Monte Carlo And Molecular Dynamics Simulations, Warin Rangubpit Jan 2020

Structure And Morphology Of Magnesium Channel By Coarse-Grained Monte Carlo And Molecular Dynamics Simulations, Warin Rangubpit

Chulalongkorn University Theses and Dissertations (Chula ETD)

Coarse-grained (CG) models have become a powerful tool for studying biomolecular complex systems with a wide range of potential applications such as large-scale protein motions, protein folding, self-assembly etc. Simulating such behaviors requires time scales which are not practically possible in all-atomistic simulations. This study presents a strategy for the application of CG simulations to investigate structural and morphological properties of cobalt-resistant magnesium channel (CorA) from Thermotoga maritima. Magnesium (Mg2+) plays a crucial function in a variety of physiological processes. The deficiency of magnesium can increase the risk of several health problems, for instance, diabetes, cardiovascular disease and osteoporosis. The …

Go to article

ตัวเร่งปฏิกิริยา Ni-Mo แบบไม่มีตัวรองรับและมีตัวรองรับสำหรับไฮโดรทรีตติงของน้ำมันปาล์มเป็นเชื้อเพลิงชีวภาพ : สมรรถนะและการนำมาใช้ซ้ำ, พจวรรณ เอี่ยมศิริ Jan 2020

ตัวเร่งปฏิกิริยา Ni-Mo แบบไม่มีตัวรองรับและมีตัวรองรับสำหรับไฮโดรทรีตติงของน้ำมันปาล์มเป็นเชื้อเพลิงชีวภาพ : สมรรถนะและการนำมาใช้ซ้ำ, พจวรรณ เอี่ยมศิริ

Chulalongkorn University Theses and Dissertations (Chula ETD)

งานวิจัยนี้เป็นการศึกษาไฮโดรทรีตติงของน้ำมันปาล์มบนตัวเร่งปฏิกิริยานิกเกิลโมลิบดีนัมแบบไม่มีตัวรองรับและมีตัวรองรับ ตัวแปรที่ศึกษาคือ ชนิดของตัวเร่งปฏิกิริยา ความเข้มข้นของสารตั้งต้น และระยะเวลาในการทำปฏิกิริยา จากการทดลองพบว่า ผลิตภัณฑ์หลักคือ สารประกอบนอร์มัลแอลเคน n-C14, n-C15, n-C16, n-C17 และ n-C18 การเพิ่มความเข้มข้นของสารตั้งต้นส่งผลให้ปฏิกิริยาไปทางดีคาร์บอกซิเลชันและดีคาร์บอนิลเลชัน การเพิ่มเวลาส่งผลให้ปฏิกิริยาไปทางไฮโดรดีออกซิจิเนชันมากกว่าดีคาร์บอกซิเลชันและดีคาร์บอนิลเลชัน ตัวเร่งปฏิกิริยานิกเกิลโมลิบดีนัมแบบไม่มีตัวรองรับ (0.2-NiMoS2) ซึ่งเตรียมจากการสลายตัวด้วยความร้อนมีประสิทธิภาพสูงสุด ภายใต้สภาวะที่เหมาะสม คือ อุณหภูมิ 300 องศาเซลเซียส ความดันไฮโดรเจนเริ่มต้น 40 บาร์ เวลา 3 ชั่วโมง ความเข้มข้นของสารตั้งต้นร้อยละ 10 โดยน้ำหนักของสารละลาย และอัตราส่วนของตัวเร่งปฏิกิริยาต่อสารตั้งต้นที่ 0.1 (w/w) ให้ร้อยละผลได้ของ แอลเคนทั้งหมด (n-C14-C18) สูงสุดที่ 67.0 โดยน้ำหนัก ในส่วนของตัวเร่งปฏิกิริยานิกเกิลโมลิบดีนัมแบบมีตัวรองรับแกมมาอะลูมินา (NiMoS2/Al2O3) ที่เตรียมจากการสลายตัวด้วยความร้อน; (H-NiMoS2/Al2O3) ที่ปริมาณ Al2O3 ร้อยละ 20 มี HDO แอกทีวิตีดี ภายใต้สภาวะที่เหมาะสม คือ อุณหภูมิ 300 องศาเซลเซียส ความดันไฮโดรเจนเริ่มต้น 50 บาร์ เวลา 3 ชั่วโมง ความเข้มข้นของสารตั้งต้นร้อยละ 5 โดยน้ำหนักของสารละลาย และอัตราส่วนของตัวเร่งปฏิกิริยาต่อสารตั้งต้นที่ 0.15 (w/w) ให้ร้อยละผลได้ของแอลเคน C14-C18 ร้อยละ 55.4 สูงที่สุด นอกจากนี้ตัวเร่งปฏิกิยา 0.2-NiMoS2 และ H-NiMoS2/Al2O3-0.2 สามารถนำกลับมาใช้ซ้ำในไฮโดรทรีตติงของน้ำมันปาล์มได้อย่างน้อย 3 รอบ แสดงให้เห็นว่าตัวเร่งปฏิกิริยายังมีประสิทธิภาพในการใช้งานได้นาน

Go to article

Synthesis Of Substituted Stilbene Probes Towards The Investigation Of Antagonistic Effects Observed With 3,5-Substituted Paraben Derivatives, Bethany Adams Jan 2020

Synthesis Of Substituted Stilbene Probes Towards The Investigation Of Antagonistic Effects Observed With 3,5-Substituted Paraben Derivatives, Bethany Adams

Longwood Senior Theses

In practice, antagonistic xenoestrogen compounds have been used as drugs to treat cancer. Traditional strategies, include preparation of estrogen receptor antagonists exhibiting high affinity for the receptor while preventing rearrangement of the AF-2 binding domain. In a potentially new strategy, substituted parabens have proven to act as antagonists but do not bear the large sidechain associated with this common antagonist strategy. Weak phenolic interactions make determining such paraben binding confirmations and mode of action difficult. To investigate these activities associated with hindered phenolic compounds, substituted bisphenol probes have been synthesized via Wittig protocols to produce a series of stilbene derivatives. …

Go to article

การผลิตไฮโดรเจนโดยไพโรไลซิสร่วมกับรีฟอร์มิงด้วยไอน้ำของพลาสติกและกลีเซอรอลโดยใช้ตัวเร่งปฏิกิริยา Ni/Al2o3, พัชรพร วิบูลย์วิมลรัตน์ Jan 2020

การผลิตไฮโดรเจนโดยไพโรไลซิสร่วมกับรีฟอร์มิงด้วยไอน้ำของพลาสติกและกลีเซอรอลโดยใช้ตัวเร่งปฏิกิริยา Ni/Al2o3, พัชรพร วิบูลย์วิมลรัตน์

Chulalongkorn University Theses and Dissertations (Chula ETD)

งานวิจัยนี้มีจุดประสงค์เพื่อศึกษาการผลิตไฮโดรเจนโดยไพโรไลซิสร่วมกับรีฟอร์มิงด้วยไอน้ำของพลาสติกและกลีเซอรอลโดยใช้ตัวเร่งปฏิกิริยานิกเกิล/อลูมินา การทดลองนี้ถูกดำเนินการในเครื่องปฏิกรณ์แบบเบดนิ่งชนิดสองขั้น ในส่วนแรกศึกษาผลของตัวเร่งปฏิกิริยานิกเกิล/อลูมินาที่ส่งผลต่อไพโรไลซิสร่วมกับรีฟอร์มิงด้วยไอน้ำในการผลิตไฮโดรเจน โดยเทียบกรณีไม่มีตัวเร่งปฏิกิริยานิกเกิล/อลูมินา จากผลการทดลองพบว่า การเติมตัวเร่งปฏิกิริยานิกเกิล/อลูมินา ส่งผลทำให้องค์ประกอบและผลได้ของไฮโดรเจนมีค่าสูงขึ้นอย่างชัดเจน และให้องค์ประกอบและผลได้ของมีเทนและคาร์บอนมอนอกไซด์ที่ลดลง ส่วนที่สองศึกษาผลของอุณหภูมิรีฟอร์มิงที่ 700, 750 และ 800 องศาเซลเซียส โดยใช้ตัวเร่งปฏิกิริยานิกเกิล/อลูมินา ภายใต้สภาวะการดำเนินงานเดียวกัน สำหรับกรณีที่ป้อนกลีเซอรอลหรือพลาสติกเดี่ยว พบว่าผลได้ของแก๊สผลิตภัณฑ์รวมมีแนวโน้มเพิ่มขึ้นตามอุณหภูมิรีฟอร์มิงที่สูงขึ้น และที่อุณหภูมิรีฟอร์มิง 750 องศาเซลเซียส มีผลได้ของไฮโดรเจนสูงสุดสำหรับกรณีที่ป้อนกลีเซอรอลร่วมกับชนิดของพลาสติกที่แตกต่างกัน จึงถือเป็นอุณหภูมิที่เหมาะสมสำหรับกระบวนการไพโรไลซิสร่วมกับรีฟอร์มิงด้วยไอน้ำของพลาสติกและกลีเซอรอล และส่วนสุดท้ายศึกษาผลของการใช้พลาสติกที่แตกต่างกันสามชนิด ได้แก่ พอลิเอทิลีน, พอลิโพรพิลีนและพอลิสไตรีน จากผลการทดลองที่ได้พบว่าการผลิตไฮโดรเจนจากกลีเซอรอลร่วมกับพอลิเอทิลีนและกลีเซอรอลร่วมกับพอลิสไตรีนมีแนวโน้มที่สูงใกล้เคียงกัน

Go to article

การหาอุณหภูมิที่เหมาะสมที่สุดของการรีดคอมพาวนด์หน้ายางและวัลคาไนเซชัน, พรทิพา ประสงค์เงิน Jan 2020

การหาอุณหภูมิที่เหมาะสมที่สุดของการรีดคอมพาวนด์หน้ายางและวัลคาไนเซชัน, พรทิพา ประสงค์เงิน

Chulalongkorn University Theses and Dissertations (Chula ETD)

กระบวนการหลักของการผลิตยางหล่อดอกคือกระบวนการคงรูปยาง ซึ่งเป็นส่วนสำคัญที่ส่งผลต่อประสิทธิภาพ การผลิตยางหล่อดอก งานวิจัยนี้มีเป้าหมายเพื่อหาอุณหภูมิการอัดรีดยางคอมพาวนด์ที่เหมาะสมในการคงรูปยางสำหรับการผลิตในโรงงาน และศึกษาสมบัติของยางที่ผ่านการคงรูปที่อุณหภูมิแตกต่างกันที่ 140 150 และ 160 องศาเซลเซียส โดยให้มีระยะเวลาการเก็บยางคอมพาวนด์ก่อนคงรูปเพื่อจำลองการเก็บรักษากรีนไทร์เป็นเวลา 1 5 และ 10 วัน ก่อนนำไปเข้าสู่กระบวนการคงรูปยางเพื่อให้ได้ระยะเวลาที่เหมาะสมในการจัดเก็บ ทดสอบหาค่าความหนืด หาปริมาณการเกิดเจลในยาง พฤติกรรมการคงรูปชองยาง และ ค่าความหนาแน่นการเชื่อมขวางของยาง รวมไปถึงสมบัติทางกลโดยการหาค่าการต้านทานแรงดึง ค่าการยืดตัว ณ จุดขาด และค่ามอดุลัส จากผลการทดสอบแสดงให้เห็นว่าระยะเวลาสกอร์ช และระยะเวลาการคงรูปยางลดลงเมื่อเพิ่มอุณหภูมิการคงรูปและระยะเวลาในการเก็บยางคอมพาวนด์ก่อนการคงรูป ค่าการต้านทานแรงดึงแปรผันตามอุณหภูมิการคงรูป ค่าความหนาแน่นการเชื่อมขวางลดลงเมื่ออุณหภูมิการอัดรีดและอุณหภูมิการคงรูปยางคอมพาวนด์เพิ่มขึ้น เช่นเดียวกับค่าความต้านทางแรงดึงและค่ามอดุลัสที่ 300 % อย่างไรก็ตามการใช้อุณหภูมิที่สูงมากในการคงรูปยางส่งผลทำให้ยางสมบัติทางกลที่ต่ำ ได้ผลผลิตยางที่มีความแข็งแรงทนทานต่ำ ต้องใช้พลังงานไอน้ำในการให้ความร้อนสูง และสิ้นเปลืองเบลดเดอร์ ดังนั้นอุณหภูมิการอัดรีดยางคอมพาวนด์ที่ 50 องศาเซลเซียสและอุณหภูมิการคงรูปยางที่ 150 องศาเซลเซียส เป็นอุณหภูมิที่เหมาะสมที่สุดที่จะให้ระยะเวลาการคงรูปที่สั้นและยังคงคุณสมบัติทางกลของยางคอมพาวนด์ที่ดีซึ่งจำเป็นต่อการปรับปรุงกระบวนการผลิตในโรงงานผลิตยางหล่อดอกเพื่อที่จะบรรลุความต้องการของลูกค้าในอนาคต

Go to article

First Prev Next Last