Chemistry Commons^™

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.

Structural Annotation Of Electro- And Photochemically Generated Transformation Products Of Moxidectin Using High-Resolution Mass Spectrometry, Lisa Kotthoff, Sarah-Louise O'Callaghan, Jan Lisec, Tanja Schwerdtle, Matthias Koch

Articles

Moxidectin (MOX) is a widely used anthelmintic drug for the treatment of internal and external parasites in food-producing and companion animals. Transformation products (TPs) of MOX, formed through metabolic degradation or acid hydrolysis, may pose a potential environmental risk, but only few were identified so far. In this study, we therefore systematically characterized electro- and photochemically generated MOX TPs using high-resolution mass spectrometry (HRMS). Oxidative electrochemical (EC) TPs were generated in an electrochemical reactor and photochemical (PC) TPs by irradiation with UV-C light. Subsequent HRMS measurements were performed to identify accurate masses and deduce occurring modification reactions of derived TPs …

Preparation Of Different Thin Film Catalysts By Direct Current Magnetron Sputtering Forhydrogen Generation, Gamze Bozkurt, Abdulkadi̇r Özer, Ayşe Bayrakçeken Yurtcan

Turkish Journal of Chemistry

In this study, thin films of Co, Ni, Pd, and Pt were prepared on Co$_{3}$O$_{4}$ support material in pellet form using the direct current (DC) magnetron sputtering method for use as catalysts for hydrogen generation from NaBH4.Characterization of the catalysts was carried out using X-ray diffraction (XRD), scanning electronic microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). According to cross-sectional SEM images, catalyst thicknesses were observed in the range of approximately 115.3-495.8 nm. The particle sizes were approximately 25.0, 21.4, 33.9, and 9.5 nm for Ni-Co$_{3}$O$_{4}$, Co-Co$_{3}$O$_{4}$, Pd-Co$_{3}$O$_{4}$, and Pt-Co$_{3}$O$_{4}$ catalysts, respectively. The increase in NaOH initial concentration provides an increase …

So$_{2}$ Sorption Properties Of Fly Ash Zeolites, Natalia Czuma, Wojciech Franus, Pawel Baran, Agnieszka Cwik, Katarzyna Zarebska

Turkish Journal of Chemistry

In the presented study, the sulfur dioxide sorption properties of fly ash zeolite X were investigated. Sorption tests were performed on fly ash zeolite samples that were not prepared specially for sorption, in addition to dried samples and samples in the presence of water vapor. The samples saturated with water vapor showed the highest sorption capacity. The sorption capacity of the samples additionally dried prior to the sorption experiment was higher than that of the samples that were not specially prepared for the sorption test. Regeneration tests indicated relatively good regeneration properties. The obtained results were described with the use …

Diclofenac Determination Using Ceo2 Nanoparticle Modified Screen-Printed Electrodes:A Study Of Background Correction, Rafaela C. De Carvalho, Tony Betts, John Cassidy

Articles

The detection of low levels of drugs including Non-Steroidal Anti-Inflammatory Drugs (NSAIDs) in natural waters and wastewaters is becoming increasingly important. Electrochemical methods offer an attractive means of detection, as they overcome many disadvantages associated with the currently available analytical methods. Cerium dioxide nanoparticles were synthesised and then incorporated onto the working electrodes of commercial graphite-based Screen Printed Carbon Electrodes (SPCE) then used to determine diclofenac levels. Following initial Cyclic Voltammetry studies, Square Wave Voltammetry (SWV) investigations were conducted over a range of conditions to optimise the peak potential separation and sensitivity of the method. The use of background correction …

Mechanistic Study Of C-H Activation By Iridium Complexes, Rozalie S G Corea

Theses and Dissertations

C-H activation is considered the “holy grail” of chemistry. Remote, selective C-H activation has many applications such as modifying precursors, adding complexity to molecules, and modifying pre- existing structures in a reduced number of steps. Previous work by Swift and Gronert identified an iridium(III) phenanthroline complex that can activate C-H bonds of cyclohexane. The objective of this dissertation is to study the mechanism and regioselectivity of this complex in common precursors, namely 1-butanol, 1-methoxybutane and butyl acetate.

The studies were carried out in the gas phase on a modified mass spectrometer. Selectively deuterated alcohol, ether and ester were used to …

Exploration Of Cis-1,2-Diaminocyclohexane-Based Conformationally Locked Chiral Ligands In Asymmetric Synthesis, Carim Van Beek

University of the Pacific Theses and Dissertations

Natural products have been demonstrated to be of great significance to the pharmaceutical industry in the development of new drugs and medicine. Unfortunately, synthetic approaches to obtain these natural products often prove increasingly challenging due to the complexity of synthesizing the target drug in the proper stereochemistry. The availability of enantioselective reactions can play a pivotal role in overcoming this challenge, yielding access to optically pure intermediates and products. Chiral ligands based on a trans-1,2-diaminocyclohexane motif are often employed for this purpose and their complexes with transition metals have been demonstrated to act as efficient chiral catalysts in asymmetric reactions. …

Elephant And Anchors ‒ Photoelectron Photoion Coincidence Spectroscopy Of Small Oxygenated Molecules, Apeter Weidner

University of the Pacific Theses and Dissertations

The dissociative photoionization reactions of two small, oxygenated organics, namely 1,3-dioxolane and methyl vinyl ketone, were studied by photoelectron photoion coincidence (PEPICO) spectroscopy. Experiments involving 1,3-dioxolane were carried out in the photon energy range of 9.5‒13.5 eV. The statistical thermodynamics model shows that a total of six dissociation channels are involved in the formation of three fragment ions, namely C3H5O2+ (m/z 73), C2H5O+ (m/z 45) and C2H4O+ (m/z 44), with two channels contributing to the formation of each. By comparing the results of ab initio quantum chemical calculations to the experimentally derived appearance energies of the fragment ions, the most …

Studies On The Size And Non-Planarity Of Aromatic Stacking Moiety On Conformation Selectivity And Thermal Stabilization Of G-Quadruplexes, Mandeep Singh

University of the Pacific Theses and Dissertations

Targeting DNA has the advantage over proteins for cancer remediation because of the fewer copies of the ligands required for the desired therapeutic effect. Traditionally, covalent DNA binders like alkylating agents have been used to induce genetic instability through the formation of DNA lesions and strand breaks, leading to cellular apoptosis. The primary drawback of this treatment is the non-specific binding that affects both cancerous and non-cancerous cells. G-quadruplexes are the DNA secondary structures that are present in abundance near the promoter regions of the oncogenes and are involved in the regulation of their activities. A ligand-mediated stabilization of G-quadruplexes …

The Fabrication And Properties Of Magnetorheological Elastomers Employing Bio-Inspired Dopamine Modified Carbonyl Iron Particles, Yanfen Zhou, Lele Li, Wenyue Li, Shipeng Wen, Liang Jiang, Stephen Jerrams, Jianwei Ma, Shaojuan Chen

Articles

To obtain magnetorheological elastomers (MREs) with improved mechanical properties and exhibiting an enhanced magnetorheological (MR) effect, bio-inspired dopamine modification has been used to improve the functionality at the surface of carbonyl iron (CI) particles. Various techniques including x-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to confirm that a polydopamine (PDA) layer of about 27.5 nm had been successfully deposited on the surface of the carbonyl iron particles prior to their inclusion in the MRE composites. The magnetic properties of PDA modified CI particles were shown to be almost the same as those …

Enhanced Covalent Interface, Crosslinked Network And Gas Barrier Property Of Functionalized Graphene Oxide/Styrene-Butadiene Rubber Composites Triggered By Thiol-Ene Click Reaction, Long Zheng, Stephen Jerrams, Tian Su, Zongchao Xu, Liqun Zhang, Li Liu, Shipeng Wen

Articles

The high gas barrier property of a rubber composite is of great significance for reducing the exhaust gas emissions due to tire rolling resistance and hence the contribution this factor makes to environmental protection. Enhanced covalent interfaces and crosslinked networks are crucial to the gas barrier property of rubber composites. In this research, γ-mercaptopropyltriethoxysilane (MPS) modified GO (MGO)/styrene-butadiene rubber (SBR) composites were prepared by a synergetic strategy of latex compounding method and thiol-ene click reaction. It was found that the mercapto groups in MGO reacted with the vinyl groups in SBR molecules through thiol-ene click reaction during the crosslinking process …

Are Electric Vehicles A Panacea For Reducing Ozone Precursor Emissions?, Gary A. Bishop

Fuel Efficiency Automobile Test Publications

No abstract provided.

On-Road Remote Sensing Of Automobile Emissions In The Denver Area: Winter 2020, Gary A. Bishop

Fuel Efficiency Automobile Test Publications

No abstract provided.

On-Road Remote Sensing Of Automobile Emissions In The Tulsa Area: Fall 2019, Gary A. Bishop

Fuel Efficiency Automobile Test Publications

No abstract provided.

Quantification Of Low-Content Encapsulated Active Cosmetic Ingredients In Complex Semi-Solid Formulations By Means Of Attenuated Total Reflectance-Infrared Spectroscopy, Franck Bonnier, Lynda Miloudi, Sandra Henry, Dominique Bertrand, Clovis Tauber, Xavier Perse, Florent Yvergnaux, Hugh Byrne, Igor Chourpa, Emilie Munnier

Articles

Attenuated total reflectance-infrared (ATR-IR) spectroscopy is a robust tool for molecular characterisation of matter. Applied to semi-solid formulations, it enables rapid and reliable data collection without pre-analytical requirements. Based on nano-encapsulated Omegalight®, a skin-lightening active cosmetic ingredient (ACI), incorporated in a hydrogel, it is first demonstrated that, despite the high water content and the chemical complexity of the samples (i.e. number of ingredients), the spectral features of the ACI can be detected and monitored. Secondly, with a total of 105 samples divided into a training set (n = 60) and an unknown set (n = 45) covering a …

Exploiting Fourier Transform Infrared And Raman Microspectroscopies On Cancer Stem Cells From Oral Squamous Cells Carcinoma: New Evidence Of Acquired Csplatin Chemoresistance, Valentina Notarstefano, Simona Sabbatini, Chiaro Pro, Alessia Belloni, Giulia Orilisi, Corrado Rubini, Hugh Byrne, Lisa Vaccari, Elisabetta Giorgini

Articles

Oral Squamous Cells Carcinoma (OSCC) is characterised by the risk of recurrence and the onset of a refractoriness response to chemotherapy drugs. These phenomena have been recently related to a subpopulation of Cancer Stem Cells (CSCs), which have either an innate or acquired drug resistance, triggered by chemotherapy treatments. In this light, to precisely target chemotherapy regimens, it is essential to improve knowledge on CSCs, with a particular focus on their molecular features. In this work, a subpopulation of CSCs, isolated by tumour sphere formation from primary OSCC cells, were treated with cisplatin for 16, 24 and 48 hours and …

K-Means And Hierarchical Cluster Analysis As Segmentation Algorithms Of Ftir Hyperspectral Images Collected From Cutaneous Tissue, Cassio Lima, Luciana Correa, Hugh Byrne, Denise Zezell

Conference papers

Fourier Transform Infrared (FTIR) spectroscopy is a rapid and label-free analytical technique whose potential as a diagnostic tool has been well demonstrated. The combination of spectroscopy and microscopy technologies enable wide-field scanning of a sample, providing a hyperspectral image with tens of thousands of spectra in a few minutes. In order to increase the information content of FTIR images, different clustering algorithms have been proposed as segmentation methods. However, systematic comparative tests of these techniques are still missing. Thus, the present paper aims to compare the ability of K-means Cluster Analysis (KMCA) and Hierarchical Cluster Analysis (HCA) as clustering algorithms …

Outstanding Reviewers For Analyst In 2019, Royal Society Of Chemistry

Articles

We would like to take this opportunity to thank all of Analyst's reviewers, and in particular highlight the Outstanding Reviewers for the journal in 2019, as selected by the editorial team for their significant contribution to Analyst. We announce our Outstanding Reviewers annually and each receives a certificate to give recognition for their contribution. The reviewers have been chosen based on the number, timeliness and quality of the reports completed over the last 12 months.

Vehicle Exhaust Remote Sensing Device Method To Screen Vehicles For Evaporative Running Loss Emissions, Gary A. Bishop, Timothy H. Defries, James A. Sidebottom, James M. Kemper

Fuel Efficiency Automobile Test Publications

Vehicle hydrocarbon (HC) emissions can be emitted from either tailpipe or non-tailpipe locations and understanding their fleet apportionment is important for successful air pollution policy. Vehicles initially misidentified as having elevated tailpipe HC emissions first indicated that roadside exhaust sensors could detect the presence of evaporative HC emissions as increased noise in the HC/carbon dioxide (CO₂) correlation measurement. The 90^th percentile of the largest residual of the HC/CO₂ correlation is defined as a running loss index (RLI) for each measurement. An RLI that is three standard deviations or greater above the instruments noise indicates possible evaporative …

Inspection And Maintenance Evaluation Using Historical U.S. Remote Sensing Measurements, Gary A. Bishop

Fuel Efficiency Automobile Test Publications

No abstract provided.

Studies On The Synthesis Of Unusual Amino Acids And Their Incorporation Into New Peptide Antibiotics, Agnieszka Wadolowska

Doctoral

As microorganisms continue to develop resistance and survive against many different forms of antimicrobial solutions, such as antibiotics, there is urgent need for new classes of antimicrobial peptides to mitigate the threat. Bacteria are a rich source of ribosomally-synthesized antimicrobial peptides known as bacteriocins, which are produced by one bacterial species to kill other bacterial strains. Lanthionine-containing lantibiotics and sactibiotics are post-translationally modified bacteriocins which display extremely potent antibacterial activity.

Thuricin CD, a two-peptide system belonging to the sactibiotic family, shows high activity, but most importantly excellent selectivity, against C. difficile infection. The Thuricin CD peptides contain a number of …

Β-Methylumbelliferone Surface Modification And Permeability Investigations At Pentel™ Graphite Electrodes, Susan Warren, Brian Seddon, Ruth Pilkington, Alison Crossely, Philip Holdway, Eithne Dempsey

Articles

Electrochemical and micro-imaging analysis of a commercial graphite-composite material is presented following electro-oxidation with β-methylumbelliferone. Charge-transfer surface modification was observed for the graphite electrode, presumed to have arisen from adsorbed interfacial umbelliferone moieties. The molecular permeability of the new surface towards a range of similar, yet size-variable (23 Å3–136 Å3) molecular redox probes is discussed. Red-shift fluorescence in confocal microscopy offers further support for the presence of a surface-bound umbelliferone layer. An SEM-platinum profiling technique was used as an imaging tool to map the umbelliferone surface and size-distribution of electroactive sites.

Thermal Atomic Layer Deposition Of Silver Metal Films: Synthesis And Characterization Of Thermally Stable Silver Metal Precursors, Harshani Jayabahu Arachchilage

Wayne State University Dissertations

ABSTRACT

THERMAL ATOMIC LAYER DEPOSITION OF SILVER METAL FILMS: SYNTHESIS AND CHARACTERIZATION OF THERMALLY STABLE SILVER METAL PRECURSORS

by

HARSHANI JAYABAHU ARACHCHILAGE

August 2020

Advisor: Professor Charles H. Winter

Major: Chemistry (Inorganic)

Degree: Doctor of Philosophy

Traditional film deposition techniques such as PVD and CVD are widely used in the microelectronics industry. However, the lack of thickness control and conformality requirements limit these techniques for current and future applications. By contrast, ALD offers the deposition of ultra-thin conformal films with accurate thickness control due to the self-limiting growth behavior. Ag metal has the lowest resistivity (1.59 µΩ cm) of all …

Use Of Confocal Raman Microscopy To Characterise Ethyl Cyanoacrylate Adhesive Depth Curing, Kevin Raheem, John Cassidy, Tony Betts, Bernard Ryan

Articles

In situ spatial temporal measurement of monomer conversion during adhesive bondline curing remains a challenging area. The aim of this work was to demonstrate the effectiveness of using confocal Raman microscopy in a specially configured experimental set-up, as a versatile tool for measuring monomer concentration changes as a function of both time and adhesive bond depth during ethyl cyanoacrylate polymerisation. This also allowed monitoring of the extent of polymerisation at the adhesive substrate interface independently of the bulk bondline polymerisation region. Key kinetic parameters such as inhibition time tlag, rate of reaction Rmax and extent of reaction [at]max were obtained …

Process For Producing Isocyanate-Based Xerogels And Aerogels With Mineral Acids, Wibke Loelsberg, Marc Fricke, Dirk Weinrich, Nicholas Leventis, Chariklia Sotiriou-Leventis, Adnan M. Saeed

Patents

The present invention is directed to a process for preparing a porous material, at least comprising the steps of providing a mixture (I) comprising a composition (A) at least comprising at least one polyfunctional isocyanate as component (ai) and at least one mineral acid (aa), and a solvent (B), reacting the components in the composition (A) obtaining an organic gel, and drying of the gel obtained. The invention further relates to the porous materials which can be obtained in this way and the use of the porous materials as thermal insulation material and as catalysts.

Identification And Characterization Of Chemical Compounds That Inhibit Leucyl-Trna Synthetase From Pseudomonas Aeruginosa, Regina Zamacona, Pamela N. Chavero, Eduardo Medellin, Yanmei Hu, Casey A. Hughes, Nathalie Quach, Megan Keniry, James M. Bullard

School of Integrative Biological & Chemical Sciences Faculty Publications

Background: Pseudomonas aeruginosa is an opportunistic multi-drug resistance pathogen implicated as the causative agent in a high-percentage of nosocomial and community acquired bacterial infections. The gene encoding leucyl-tRNA synthetase (LeuRS) from P. aeruginosa was overexpressed in Escherichia coli and the resulting protein was characterized.

Methods: LeuRS was kinetically evaluated and the KM values for interactions with leucine, ATP and tRNA were 6.5, 330, and 3.0 μM, respectively. LeuRS was developed into a screening platform using scintillation proximity assay (SPA) technology and used to screen over 2000 synthetic and natural chemical compounds.

Results: The initial screen resulted in the identification of …

General Chemistry Students' Perceived Self-Efficacy After Completing Project-Based Service-Learning Activities, Sarah Quast Sliker

Walden Dissertations and Doctoral Studies

A New England community college reported that 60% of General Chemistry college students, who were science, technology, engineering, and mathematics (STEM) majors, did not advance in the STEM curriculum. To potentially increase student persistence in STEM curriculum, this qualitative case study project explored the self-efficacy perceptions of General Chemistry students after participating in project-based service-learning with elementary-school students. Bandura's social cognitive theory provided the conceptual framework for the study, supporting an understanding of learner self-efficacy. Research questions focused on chemistry students perceived self-efficacy after interactions with elementary-school students, teamwork, and the development of a project. Semistructured interviews with 10 participants …

Factors Influencing Huntingtin Aggregation At Surfaces: Implications For Huntington’S Disease, Sharon E. Groover

Graduate Theses, Dissertations, and Problem Reports (ETD)

Huntington’s Disease (HD) is a genetic, neurodegenerative disease characterized by an abnormal polyglutamine (polyQ) expansion in the first exon of the huntingtin protein (htt). The polyQ domain facilitates aggregation and initiates the formation of a diverse collection of aggregate species, including fibrils, oligomers and annular aggregates. The first 17 amino acids of htt (Nt17) directly flank the polyQ domain and is a key factor in htt’s association to membranous structures. In addition to Nt17 being an amphipathic αhelix, it also promotes aggregation through self-association and contains numerous posttranslational modifications (PTMs) that can modulate toxicity and subcellular localization. For in depth …

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 (Z_C), a metric calculated from the chemical formulae of lipid structures. Carbon in intact polar lipids (IPLs) and their alkyl chains becomes …