Chemistry Commons^™

ผลของแอโรมาติกพอลิเอสเทอร์พอลิออลต่อสมบัติของโฟมพอลิไอโซไซยานูเรตแบบแข็ง, สุวมิตร เชื่อมชิต

Chulalongkorn University Theses and Dissertations (Chula ETD)

งานวิจัยนี้ศึกษาผลจากการใช้แอโรมาติกพอลิเอสเทอร์พอลิออลสองชนิด คือ พอลิออล A และพอลิออล B เป็นองค์ประกอบหลักต่อสมบัติของโฟมพอลิไอโซไซยานูเรตแบบแข็ง โดยพอลิออล A และพอลิออล B มีค่าหมู่ไฮดรอกซิลต่างกัน คือ 220 และ 350 mg.KOH/g ตามลำดับ เตรียมโฟมด้วยดัชนีไอโซไซยาเนตที่ 250, 280 และ 300 ศึกษาเวลาที่ใช้ในการเกิดปฏิกิริยา คือ เวลาที่สารผสมเป็นครีม เวลาที่สารผสมเป็นเจล เวลาที่โฟมหยุดฟู และเวลาที่ผิวหน้าของโฟมไม่เกาะติดกับผิวสัมผัสของวัสดุ สมบัติเชิงกายภาพและสมบัติเชิงกลของโฟมที่ศึกษามีดังนี้ คือ ความหนาแน่น การเปลี่ยนแปลงของหมู่ไอโซไซยาเนตและอัตราส่วนระหว่างหมู่ไอโซไซยานูเรตและหมู่ยูรีเทน ความต้านทานต่อแรงกดอัด สัณฐานวิทยา เสถียรภาพทางความร้อน ค่าการนำความร้อน และสมบัติการป้องกันการลามไฟ จากการศึกษาพบว่าโฟมพอลิไอโซไซยานูเรตที่เตรียมจากพอลิออล B สูตร F6 ที่ดัชนีไอโซไซยาเนต 280 มีสมบัติที่ใกล้เคียงกับเป้าหมายที่ต้องการ คือ ความหนาแน่น 35-40 kg/m3 ค่าการนำความร้อนที่น้อยกว่าหรือเท่ากับ 0.023 W/mK และผ่านการทดสอบมาตรฐานการลามไฟ DIN 4102-B2 ดังนั้น สูตรการผลิตโฟมจากพอลิออล B สูตร F6 ที่ดัชนี 280 มีความเป็นไปได้ที่จะนำไปใช้ในงานเชิงอุตสาหกรรม

Dye-Encapsulated Ethyl Cellulose As Fluorescence Sensor For Aldehyde Detection, Jinnawat Jongkhumkrong

Chulalongkorn University Theses and Dissertations (Chula ETD)

Over past years, even though lung cancer as one of vital cancer-related mortalities worldwide has inevitably exhibited the highest death rate of entire cancers, there is no facile and convenient diagnosis approaches. The previous researches have reported about long-chain aldehyde compounds such as hexanal, heptanal, octanal, and nonanal as the crucial biomarkers of lung cancer. Nevertheless, the sensing platform for long-chain aldehyde detection have been rarely reported. In this research, the helicene dye-encapsulated ethyl cellulose (EC@dye-NH) nanosensors have achieved the potentially sensitive and specific detection of long-chain aldehyde in aqueous media. As a proof-of-concept, the intrinsic hydrazine group of dye-NH …

Electrolytic Oxidative Coupling Of Alcohols With Aldehydes To Form Esters, Katherine L. Verboom

Honors College Theses

There are copious amounts of naturally occurring and synthetic esters known that have a wide range of applications in industry to produce fine chemicals. Traditional methods of ester synthesis involve a reaction between a carboxylic acid and an alcohol in the presence of a Bronsted acid catalyst. The primary objective of this research project was to carry out the ester synthesis using the electrochemical coupling of aldehydes with alcohols instead of with a Bronsted acid catalyst because the electrochemical coupling would be an all-around better alternative of ester synthesis than the traditional method of using the catalyst. Electrochemistry has long …

Chemical Process Development, University Of North Dakota. Energy And Environmental Research Center

EERC Brochures and Fact Sheets

Fact sheet on the Energy & Environmental Research Center’s chemical process development capabilities.

Optimization Of Dapoxyl Aptamer For Label-Free Bioanalysis, Jack E. Mordeson, Ryan P. Connelly, Pedro F. Madalozzo, Yulia Gerasimova

Digital Repository: Showcase of Undergraduate Research Excellence

No abstract provided.

Design, Construction, And Characterization Of A Combined Mini-Co₂/Voc Sensor And Gas Chromatograph For Field Research, Rishi Basdeo, Michael Hampton

Digital Repository: Showcase of Undergraduate Research Excellence

No abstract provided.

Synthesis Of Guanidines From Thioureas Using Photocatalyst, Trin Sae-Tan

Chulalongkorn University Theses and Dissertations (Chula ETD)

In this study, a photo catalytic guanylation is investigated using Ru(bpy)3Cl2 as a photocatalyst under visible light irradiation. The reaction can be performed in green solvent such as ethanol and water and non-toxic K2CO3 base using 1-5% of Ru(bpy)3Cl2 under 19W white LED irradiation. Under optimized condition, this method can be applied for guanylation of various thioureas carrying a variety of functional groups with morpholine. Moreover, the amine scope includes primary and secondary amine carrying various functional groups. As the result, more than twenty examples of guanidine products can be produced in fair to excellent yields. Moreover, the reaction can …

Synthesis, Characterization, And Reactivity Of Palladium Proazaphosphatrane Complexes, Adrian D. Matthews

Honors Theses

Palladium-catalyzed cross-coupling reactions provide an efficient pathway to a wide variety of otherwise inaccessible compounds. In this study, the synthesis and reactivity of novel palladium proazaphosphatrane complexes that are believed to be intermediates in C–N cross-coupling reactions are described. Both the fundamental reactivity of these complexes and elementary steps involved in a catalytic process are demonstrated. The catalytic viability of palladium proazaphosphatrane complexes is shown through stoichiometric and catalytic cross-coupling reactions. Our findings support the long-standing hypothesis that proazaphosphatranes are conformationally flexible ligands that stabilize a number of catalytic intermediates.

A Model Experiment To Investigate The Possibility Of Glyphosate Contamination In St. Kitts And Nevis, Winston Fu

Honors Undergraduate Theses

Glyphosate is a broad-spectrum herbicide that is used globally to combat the spread of weeds among crops. Not all countries around the world have been using the herbicide. For example, island countries such as Dominica and St. Kitts and Nevis do not use the herbicide on their crops. However, St. Kitts and Nevis imports food and other agricultural products from around the world, leading to the hypothesis that glyphosate is contaminating the soil through those imported products. The aim of this research project was to determine if glyphosate is present in the island country of St. Kitts and Nevis. A …

Seaweed As A Carrier For Microplastics, Stephanie M. Rodriguez

Honors Undergraduate Theses

Analysis of seaweed as a vector for microplastics is an integral part of understanding the formation and deposition of micro-sized plastic waste in seawater. The project itself originated due to the influx of seaweed (and mismanaged plastic waste) residing on the shores of St. Kitts and Nevis and the constant deposition of plastic pollution intertwined within the seaweed. The natural occurrence of the two together lead to the consideration of fragmented plastics remaining on the seaweed. The objective of this research is to stain, identify, and quantify the concentration of microplastics sourced from both store-bought and environmental seaweed samples. A …

A Nested Pcr Strategy For Recovering Highly Discriminatory Y-Str Dna Profiles From Trace Male Dna Samples, Anna Kimball

Electronic Theses and Dissertations, 2020-2023

DNA profiling is an effective method of identifying individuals in forensic casework. In sexual assault cases in particular, male donor DNA can be genotyped using Y chromosome short tandem repeat (Y-STR) analysis even in the presence of significant levels of female DNA. The recently released recommended national standard for sexual assault evidence collection from the victim is within 5 days after the sexual assault, with the probability of obtaining a male DNA profile diminishing significantly thereafter due to degradation and/or loss of sperm. The present study was designed to develop a method of obtaining a highly probative DNA profile with …

A Solid-Solution Approach To Multivariate Metal-Organic Frameworks And Their Interactions With Light, Wesley Newsome

Electronic Theses and Dissertations, 2020-2023

This thesis studies the application of a substitutional solid solution (SSS) approach to multivariate metal organic frameworks (MTV MOFs) with a focus on preparing functional organic-inorganic materials. MOFs are a class of crystalline coordination polymers that form 3-dimensional structures with pores. The empty space in the unit cell of these materials allows for the incorporation of functionalized links and leads to a sub-class known as MTV MOFs, where multiple links of varied functionality are incorporated into the same material. MTV MOFs function similarly to the inorganic concept of SSS were a solute atom is dissolved inside a matrix, allowing for …

Microdialysis: A Method For Quantifying In Situ Nitrogen Fluxes In Soil Microsites, Srusti Maddala, Mary C. Savin, Julie A. Stenken, Lisa S. Wood

Discovery, The Student Journal of Dale Bumpers College of Agricultural, Food and Life Sciences

Microdialysis, a diffusion-based sampling technique commonly used in biomedical research, has recently been recognized as a candidate for monitoring chemical changes in the rhizosphere. The information it provides about nutrient diffusion may improve nitrogen use efficiency, leading to enhanced management and success of restoration projects. The objective of this study was to determine the efficacy of microdialysis sampling to quantify the relative recoveries (RR%) of nitrate-N and ammonium-N, the two inorganic nitrogen compounds typically found in soil. The effects of microdialysis flow rate, sample medium concentration, and the presence of both analytes in solution on the relative recoveries obtained from …

New Rna Research Demonstrates Prebiotic Possibility, David W. Ball

Chemistry Faculty Publications

No abstract provided.

Methyl Ketones From Carboxylic Acids As Valuable Target Molecules In The Biorefinery, Olivier Marie, Alexey Ignatchenko, Michael Renz

Chemistry Faculty/Staff Publications

For the preparation of methyl ketones, cross Ketonic Decarboxylation, i.e., the formation of a ketone from two different carboxylic acids, and the reketonization, i.e., the transformation of a carboxylic acid into a ketone employing a ketone as alkyl transfer agent, may be interesting alternatives to classical pathways involving metal-organic reagents.

The fine chemical 2-undecanone was chosen as model compound and ketonic decarboxylation and reketonization evaluated by Green Chemistry matrices, namely the carbon atom efficiency and the e-factor. The e-factor of the reaction of decanoic acid with acetic acid was less than five and, therewith, in the acceptable range for bulk …

Correlating The Physicochemical Properties Of Magnesium Stearate With Tablet Dissolution And Lubrication, Julie L. Calahan

Theses and Dissertations--Pharmacy

Magnesium stearate (MgSt) is the most commonly used pharmaceutical excipient and is present in over half the tablet formulations on the market. In spite of its popularity as an effective lubricant, it has been repeatedly recognized that there is significant variability between MgSt samples, which can cause inconsistent lubrication between batches of MgSt. The hypothesis of this research is that the batch-to-batch variability in tablet lubrication and dissolution observed in tablet formulations containing different MgSt samples can be correlated with differences in MgSt physicochemical properties (fatty acid salt composition, crystal hydrate form, particle size and surface area). Developing correlations between …

Carbon Oxidation At The Atomic Level: A Computational Study On Oxidative Graphene Etching And Pitting Of Graphitic Carbon Surfaces, Simon Schmitt

Theses and Dissertations--Mechanical and Aerospace Engineering

In order to understand the oxidation of solid carbon materials by oxygen-containing gases, carbon oxidation has to be studied on the atomic level where the surface reactions occur. Graphene and graphite are etched by oxygen to form characteristic pits that are scattered across the material surface, and pitting in turn leads to microstructural changes that determine the macroscopic oxidation behavior. While this is a well-documented phenomenon, it is heretofore poorly understood due to the notorious difficulty of experiments and a lack of comprehensive computational studies. The main objective of the present work is the development of a computational framework from …

Gravity-Drawing Flexible Silicone Filaments As Fiber Optics And Model Foldamers, Katherine Snell

CMC Senior Theses

Here, we present a method of gravity-drawing polydimethylsiloxane (PDMS) silicone fibers with application as fiber optics and as model foldamers. Beginning as a viscous liquid, PDMS is cured using heat until its measured viscosity reaches 4000 mPa•s. The semi-cured elastomer is then extruded through a tube furnace to produce thin (diameters on the order of hundred micrometers) filaments with scalable lengths. PDMS is biocompatible, gas-permeable, flexible, and hydrophobic. Additionally, the PDMS surface hydrophobicity can be modified via UV exposure, O2 plasma, and corona discharge. We demonstrate the patternibility (i.e patterns of hydrophobicity) of PDMS fibers, adding complexity to potential foldamer …

Modeling Iron And Light Controls On The Summer Phaeocystis Antarctica Bloom In The Amundsen Sea Polynya, Hilde Oliver, Pierre St-Laurent, Robert M. Sherrell, Patricia L. Yaeger

CCPO Publications

Of all the Antarctic coastal polynyas, the Amundsen Sea Polynya is the most productive per unit area. Observations from the 2010-2011 Amundsen Sea Polynya International Research Expedition (ASPIRE) revealed that both light and iron can limit the growth of phytoplankton (Phaeocystis antarctica), but how these controls manifest over the bloom season is poorly understood, especially with respect to their climate sensitivity. Using a 1-D biogeochemical model, we examine the influence of light and iron limitation on the phytoplankton bloom and vertical carbon flux at 12 stations representing different bloom stages within the polynya. Model parameters are determined by …

Formation Of P-N Junctions In Nanoparticle Cerium Oxide Electrolytic Cells Displaying Memristive Switching Behaviour, Rafaela Cristina De Carvalho, Tony Betts, John Cassidy

Articles

A macro-scale metal–semiconductor–metal device comprising CeO₂ nanoparticles cast from a suspension of cerium dioxide formed by a novel synthetic method was fabricated. Thin CeO₂ films of 40 nm thickness placed between panels of aluminium and/or copper displayed memristive-like resistive switching behaviour upon the application of potential sweeps ranging between −0.6 V and 0.6 V. A mechanism is proposed based on the notion that an electrolytic cell operates under such conditions with the initial formation of p and n-type regions within the central semiconductive thin film. Evidence is presented for the existence of numerous point defects in these nanosized …

An Ammonia Sensor Using An Unadorned Bromocresol Layer, John Cassidy, Caoimhe Ní Néill, Merve Akdağ, Tony Betts

Articles

Bromocresol Purple,(BCP) cast onto an acetate sheet, was used to sense ammonia. This simple layer responded reversibly to a low concentration ( 15 ppm) of ammonia in the presence of water vapour. The BCP solution was spincoated on an acetate sheet from a solution in dichloromethane. This layer was exposed to nitrogen and NH3/H2O vapour in quick succession. The colour change occurred from yellow to purple rapidly in the solid state. The λmax for the neutral ( acid) form of the BCP was found to be 435 nm and the λmax for the dianion ( base form) of the BCP …

Determination Of Integrity, Stability And Density Of The Dna Layers Immobilised At Glassy Carbon And Gold Electrodes Using Ferrocyanide, John Colleran, Anna Banasiak

Articles

The technique chosen to immobilise DNA onto electrodes can determine the density and stability of the resultant immobilised layer. DNA‐modified electrodes were prepared using four common DNA immobilisation methods and characterised using ferrocyanide. The negatively charged DNA strands should repel ferrocyanide anions. The DNA layers created using adsorption at glassy carbon electrodes were unstable, while those created through chemisorption of thiol‐modified DNA onto gold electrodes were repeatable and stable, and returned, on average, 94 % repulsion of the probe. The presented results show how the immobilisation protocol, and DNA type, affects the stability, repeatability, and integrity of resultant DNA layers.

Gc-Ms Analysis Of Synthesized Biodiesel, Courtney R. Whetstine

Forensic Science Master's Projects

Biodiesel is an alternative energy resource that can replenish depleting natural petroleum storage. Synthesis of biodiesel is cost-efficient as it can be chemically converted from renewable wastes, such as vegetable oil or animal fat. These fuels are also biodegradable and the exhaust emissions from biodiesel are non-toxic and environmentally-friendly. Biodiesel is a stable fuel that performs reliably in all diesel engines. Biodiesel is also easy to synthesize, safe to handle, and works with diesel fuel storage and pumping systems. The United States has an abundance of vegetable oils that have not been widely used to our advantage. Additionally, fast-food restaurants …

Hydrotalcite Framework Stabilized Ruthenium Nanoparticles (Ru/Htal): Efficient Heterogeneous Catalyst For The Methanolysis Of Ammonia-Borane, İsmai̇l Burak Bağuç, Mehmet Yurderi̇, Gülşah Saydan Kanberoğlu, Ahmet Bulut

Turkish Journal of Chemistry

Ruthenium nanoparticles stabilized by a hydrotalcite framework (Ru/HTaL) were prepared by following a 2-step procedure comprising a wet-impregnation of ruthenium(III) chloride precatalyst on the surface of HTaL followed by an ammonia-borane (NH$_{3}$BH$_{3}$) reduction of precatalyst on the HTaL surface all at room temperature. The characterization of Ru/HTaL was done by using various spectroscopic and visualization methods including ICP-OES, P-XRD, FTIR, $^{11}$B NMR, XPS, BFTEM, and HRTEM. The sum of the results gained from these analyses has revealed the formation of well-dispersed and highly crystalline ruthenium nanoparticles with a mean diameter of 1.27 ± 0.8 nm on HTaL surface. The catalytic …

Investigation Of The Effect Of Pan And Pan/Zno Photocatalysts On 100% Degradation Of Congo Red Under Uv Visible Light Irradiation And Lightless Environment, Si̇bel Zor, Bi̇lge Budak

Turkish Journal of Chemistry

PAn (polyaniline) and PAn/ZnO photocatalysts were synthesized using chemical polymerization of aniline. The structure characterization of the synthesized samples was analysed by using X-ray diffraction (XRD), Fourier transforminfraredspectroscopy(FT-IR),scanningelectronmicroscopy(SEM),transmissionelectronmicroscopy(TEM), and UV-Vis spectroscopy measurements, and thermal gravimetric analysis (TGA). The photocatalytic activities of PAn and PAn/ZnO (0.1g/100ml) on the degradation of the Congo red (CR) dye were studied under the UV visible light irradiation and the lightless environment and the efficiency of catalysts have been explained in details. Contribution of UV visible light irradiation on the 100% degradation of CR dye for the PAn and PAn/ZnO photocatalyst is determined. The reaction kinetics …

2-[(3-Aminoalkyl-(Alkaryl-,Aryl-))-1 H-1,2,4-Triazol-5-Yl]Anilines: Synthesis And Anticonvulsant Activity, Yulya Martynenko, Galina Berest, Nina Bukhtiayrova, Igor Belenichev, Oleksiy Voskoboinik, Sergiy Kovalenko

Turkish Journal of Chemistry

The presented work is devoted to the development of synthesis methods for novel 2-[(3-aminoalkyl-(alkaryl-, aryl-))-1$H$-1,2,4-triazolo]anilines. Abovementioned compounds were obtained via hydrazinolysis (Ing-Manske procedure) and acid hydrolysis of corresponding $N$-acylated {([1,2,4]triazolo[1,5-$c$]quinazolin-2-yl)alkyl-(alkaryl-, aryl-)} amines. The regioselectivity of hydrazinolysis and hydrolysis were established. The features of spectral characteristics were studied and discussed. Characteristic patterns of protons signals splitting in $^{1}$H NMR of the synthesized compounds were established. The effect of the synthesized compounds on the pentylenetetrazol seizures was studied. It was found that according to some indicators, anticonvulsant activity of 2-[(3-aminoalkyl-(alkaryl-, aryl-))-1$H$-1,2,4-triazolo]anilines superior or comparable with effect of the reference drug "Lamotrigine". It …

New Sandwich-Type Polymeric Potassium-Dicyanoargentate(I) Complex: Synthesis, Characterization And Enzymatic Activity, Nesri̇n Korkmaz

Turkish Journal of Chemistry

Coordination compounds containing dicyanoargentate(I) have remarkable biological potential due to their therapeutic antibacterial, antifungal, antibiofilm, and anticancer properties. In this study, a new dicyanoargentate(I)-based complex was synthesized and characterized by various procedures (elemental, thermal, FT-IR for complex) involving crystal analysis of the complex. In addition, the biological activity of this new compound on the acetylcholinesterase (AChE) enzyme, an important enzyme for the nervous system, was investigated. When the infrared (IR) spectrum of the complex is examined, the OH vibration peak resulting from H$_{2}$O molecules in the structure at 3948-3337 cm$^{-1}$ and at 2138 cm$^{-1}$, along with a CN peak coordinated …

Voltammetric Determination Of Itopride Using Carbon Paste Electrode Modified With Gd Doped Tio$_{2}$Nanotubes, Abdulaziz Nabil Amro, Khadijah Emran, Hessah Alanazi

Turkish Journal of Chemistry

In the present work TiO$_{2}$ nanotubes (TNT) have been synthesized by alkaline hydrothermal transformation. Then they have been doped with Gd element. Characterizations of doped and undoped TNT have been done with TEM and SEM. The chemical composition was analyzed by EDX, Raman and FTIR spectroscopy. The crystal structure was characterized by XRD. Carbon paste electrode has been fabricated and mixed with Gd doped and undoped TNT to form a nanocomposite working electrode. Comparison of bare carbon paste electrode and Gd doped and undoped TNT carbon paste electrode for 1.0 × 10$^{-3}$ M K$_{4\, }$[Fe(CN)$_{6}$] voltammetric analysis; it was observed …

A Comparative Study On The Monovalent And Divalent Cation Separation Of Polymeric Films And Membranes From Salt Solutions Under Diffusion-Dialysis, Serkan Acar, Hacer Yeşi̇m Cengi̇z, Ayça Ergün, Eymen Konyali, Hüseyi̇n Deli̇göz

Turkish Journal of Chemistry

This study deals with selective separation of mono- and divalent cations from aqueous salt solutions using polymeric films based on polyethylene (PE) and polyamide6 (PA6), and two different commercial nanofiltration (NF) membranes. The diffusion rates (D) of ions (Na$^{+}$ and Ca$^{2+})$, separation factors ($\alpha )$ and ion rejections (R) of the films and NF membranes are examined comparatively as well as their surface morphology and hydrophilicity. It is observed that the diffusion rates of Na$^{+}$are in the range of 0.7-1.8 $\times $ 10$^{-8}$cm$^{2}$.s$^{-1\, }$in the decreasing order of PE $>$ NF90 $>$ NF270 $>$ PA6 while Ca$^{2+\, …

Application Of Synthesized Copper Nanoparticles Using Aqueous Extract Ofziziphus Mauritiana L. Leaves As A Colorimetric Sensor For The Detection Of Ag$^{+}$, Roomia Memon, Ayaz Ali Memon, Syed Tufail Hussain Sherazi, Siraj Uddin, Aamna Balouch, Muhammad Raza Shah, Sarfaraz Ahmed Mahesar, Kauser Rajar, Muhammad Hassan Agheem

Turkish Journal of Chemistry

The presented work demonstrates the preparation of copper nanoparticles (CuNPs) via aqueous leaves extract of Ziziphus mauritiana L. (Zm) using hydrazine as a reducing agent. Various parameters such as volume of extract, concentration of hydrazine hydrate, concentration of copper chloride, and pH of the solution were optimized to obtain Ziziphus mauritiana L. leaves extract derived copper nanoparticles (Zm-CuNPs). Brownish red color was initial indication of the formation of Zm-CuNPs while it was confirmed by surface plasmon resonance (SPR) band at wavelength of 584 nm using ultraviolet-visible (UV-vis) spectroscopy. Synthesized Zm-CuNPs were characterized by Fourier transform infrared spectroscopy (FT-IR), scanning electron …