Roaming Transition States And Highly Accurate Thermochemistry: A Pepico Study Of Two Small Combustion Systems,
2019
University of the Pacific
Roaming Transition States And Highly Accurate Thermochemistry: A Pepico Study Of Two Small Combustion Systems, Kyle John Covert
University of the Pacific Theses and Dissertations
Two small combustion systems, methyl hydroperoxide (CH3OOH) and 2-propanol ((CH3)2CHOH), were studied using imaging photoelectron photoion coincidence spectroscopy (iPEPICO), which combines photoelectron spectroscopy and photoionization mass spectrometry to detect coincident photoelectron-photoion pairs. In the photon energy range of 11.4–14.0 eV, energy selected CH3OOH+ ions dissociate into CH2OOH+, HCO+, CH3+, and H3O+ ions. The lowest-energy dissociation channel is the formation of the cation of the smallest “QOOH” radical, CH2OOH+. A statistical rate model fitted to the …
Investigation Of Coastal Sea-Fog Formation Using The Wibs (Wide Band Integrated Bioaerosol Sensor) Technique,
2019
University College Cork, Ireland
Investigation Of Coastal Sea-Fog Formation Using The Wibs (Wide Band Integrated Bioaerosol Sensor) Technique, Shane M. Daly, David O'Connor, David A. Healy, Stig Hellebust, Jovanna Arndt, Eoinj. Mcgillicuddy, Patrick Feeney, Michael Quirke, John C. Wenger, John R. Sodeau
Articles
Abstract. A wideband integrated bioaerosol sensor (WIBS4) was deployed in Haulbowline Island, Cork Harbour, to detect fluorescence particles in real time during July and September 2011. A scanning mobility particle sizer (SMPS) was also installed providing sizing analysis of the particles over the 10–450nm range. During the campaign, multiple fog formation events occurred; they coincided with dramatic increases in the recorded fluorescent particle counts. The WIBS sizing and fluorescence intensity profiles indicated that the origin of the signals was potentially non-biological in nature (i.e. PBAPs, primary biological aerosol particles). Furthermore, the data did not support the presence of known fluorescing …
Physical And Chemical Trace Evidence From 3d-Printed Firearms, And Use Of A Quadcopter For Targeted Sampling Of Gaseous Mercury In The Atmosphere,
2019
University of Mississippi
Physical And Chemical Trace Evidence From 3d-Printed Firearms, And Use Of A Quadcopter For Targeted Sampling Of Gaseous Mercury In The Atmosphere, Oscar Beauchamp Black
Electronic Theses and Dissertations
My forensic research resulted in the first peer-reviepaper to address the forensic challenges presented by 3D-printed polymer firearms. The work involved a systematic approach to the analysis of evidence stemming from 3D-printed firearms filling a critical void in current forensic knowledge. We used DART-MS to characterize the polymer evidence left behind by 3D-printed firearms as well as an evaluation of pre-existing firearm and toolmark techniques and fingerprint analysis. We demonstrated that 3D-printed firearms leave behind characteristic polymer residue on cartridge cases bullets and the receiving surface which can be identified using DART-MS. The culmination of the work includes a database …
Application Of Urinary Metabolites For Cancer Detection,
2019
University of Texas at El Paso
Application Of Urinary Metabolites For Cancer Detection, Qin Gao
Open Access Theses & Dissertations
Prostate cancer (PCa) is the 3rd most common cause of male cancer mortality in the US. Early diagnosis and treatment of PCa will improve the quality of care and reduce mortality. The prostate specific antigen (PSA) is commonly used in the current PCa screening, but its limitation has resulted in an intense search for more reliable biomarkers. Studies showed that dogs could differentiate PCa patients from negative control by sniffing their urine. As the odor profiles are generated by volatile organic compounds (VOCs), the finding suggests that particular VOCs could be linked to PCa, PCa risk levels and other cancers. …
Xflow: An Algorithm For Extracting Ion Chromatograms,
2019
University of Montana, Missoula
Xflow: An Algorithm For Extracting Ion Chromatograms, Mathew M. Gutierrez, Rob Smith
Graduate Student Theses, Dissertations, & Professional Papers
Abstract: Mass spectrometry is a fundamental tool for modern proteomics. The increasing availability of mass spectrometry data paired with the increasing sensitivity and fidelity of the instruments necessitates new and more potent analytical methods. To that end, we have created and present XFlow, a feature detection algorithm for extracting ion chromatograms from MS1 LC-MS data. XFlow is a parameter-free procedurally agnostic feature detection algorithm that utilizes the latent properties of ion chromatograms to resolve them from the surrounding noise present in MS1 data. XFlow is designed to function on either profile or centroided data across different resolutions and instruments. This …
Chemical Kinetics Using A Smartphone Spectrometer,
2019
The University of Akron
Chemical Kinetics Using A Smartphone Spectrometer, Mary Greggila
Williams Honors College, Honors Research Projects
In a time where many high school science classes are lacking in quality laboratory education, there is a need for accessible chemical equipment that enhance teaching fundamental concepts of chemistry with ease and at a low cost. The DualSpec handheld smartphone spectrometer aims to be a quality open-source spectroscopic instrument that can easily be made and used at home by people of any scientific level. This research sought to show that the DualSpec could be used to teach higher level spectroscopic concepts such as those used in chemical kinetics. The DualSpec was compared to a commercial spectrometer using the commonly …
Multidimensional Mass Spectrometry Of Chemonic™ Ccg-6 Nonionic Surfactant With Separation By Polarity And Shape,
2019
The University of Akron
Multidimensional Mass Spectrometry Of Chemonic™ Ccg-6 Nonionic Surfactant With Separation By Polarity And Shape, Charles Johnson
Williams Honors College, Honors Research Projects
Chemonic™ CCG-6 surfactant is a water-soluble poly(ethylene glycol) (PEG) conjugated alkyl glyceride emollient. This surfactant exists as a complex mixture of a glycerol cores conjugated with poly(ethylene glycol) branches (PEGylation) that were partially esterified with caprylic (C8) and capric (C10) acids. These may be esterified on one, two, or all three arms of the glyceride. The architecture of the structures in this mixture was studied using multidimensional mass spectrometry (MS). Mass spectrometry was interfaced with ultra-performance liquid chromatography (UPLC) and ion mobility (IM) separation. The mixture was separated by reversed-phase LC, oligomers of the star-branched polymer were separated according to …
Explosive Residue Transfer From Various Explosive Ordinance Disposal (Eod) Render Safe Procedures (Rsp),
2019
Virginia Commonwealth University
Explosive Residue Transfer From Various Explosive Ordinance Disposal (Eod) Render Safe Procedures (Rsp), Joseph A. Stein
Master of Science in Forensic Science Directed Research Projects
Before an IED is sent to a laboratory for analysis, it needs to be rendered safe if it did not already initiate. Render safe procedures (RSPs) include utilizing a percussion-actuated non-electric (PAN) disrupter or a mineral water bottle disrupter. Each disrupter utilizes explosives to render the device safe by breaking open the container or disrupting the fuzing system. However, the same explosives used in the RSP are also used by criminals in IED construction. As such, the explosives used in the RSP can cause problems with the interpretation of the results from forensic analysis of the IED fragments. Compounds of …
Method Considerations For Compound Identification In Complex Mixtures Using Electrospray Ionization Ultrahigh Resolution Mass Spectrometry,
2019
Michigan Technological University
Method Considerations For Compound Identification In Complex Mixtures Using Electrospray Ionization Ultrahigh Resolution Mass Spectrometry, Tyler Leverton
Dissertations, Master's Theses and Master's Reports
Biomass burning aerosols are highly complex organic mixtures of thousands of components with consequences for global climate. Complex mixture component identification requires accurate mass measurement capability to separate components on a milli-Dalton scale, frequently using ultrahigh resolution mass spectrometry with electrospray ionization. Certain sample preparations and the ionization process may introduce artifacts that obscure the composition of the sample. Two method considerations were explored using isotopically labeled 15NH4OH and MeOH-d3 to track artifact formation in biomass burning samples. Informatics techniques and a custom molecular formula assignment software were used to identify the isotopic atoms in artifact …
Diisopropylammonium Bromide Based Two-Dimensional Ferroelectric Monolayer Molecular Crystal With Large In-Plane Spontaneous Polarization,
2019
University of Nebraska-Lincoln
Diisopropylammonium Bromide Based Two-Dimensional Ferroelectric Monolayer Molecular Crystal With Large In-Plane Spontaneous Polarization, Liang Ma, Yinglu Jia, Stephen Ducharme, Jinlan Wang, Xiao Cheng Zeng
Xiao Cheng Zeng Publications
In light of their easy processing, light weight and mechanical flexibility, ferroelectric molecular crystal with large spontaneous polarization (Ps) is highly desired for many advanced applications. Herein, we report the first theoretical study of two-dimensional (2D) ferroelectric molecular crystals via ab initio calculations. Specifically, we show that diisopropylammonium bromide (DIPAB) based 2D ferroelectric monolayer molecular crystal with large in-plane Ps of ∼1.5 × 10−6 μC cm−1 can be achieved by slicing the bulk DIPAB along a specific plane while keeping the space group unchanged. The important roles of hydrogen bonds are …
The Inductive Effect In Organic Chemistry,
2019
University of Nebraska-Lincoln
The Inductive Effect In Organic Chemistry, Charles A. Kingsbury
Department of Chemistry: Faculty Publications
The subtle difference between the successive polarization model and the flow of electrons through sigma bonds is explored, as well as the alternating charge model of Pople and the pervasive field model. The present paper is concerned with the ability of alkyl groups to serve as sigma inductive electron donors.
Electrocaloric Effect In Ferroelectric Ceramics With
Point Defects,
2019
Xi'an Jiaotong University
Electrocaloric Effect In Ferroelectric Ceramics With Point Defects, Ming Wu, Qingshan Zhu, Jianting Li, Dongsheng Song, Honghui Wu, Mengyao Guo, Jinghui Gao, Yang Bai, Yujun Feng, Stephen J. Pennycoock, Xiaojie Lou
Department of Chemistry: Faculty Publications
The electrocaloric effect has drawn much attention due to its potential application in cooling devices. A negative electrocaloric effect is predicted to be induced in defect-doped ferroelectrics by computational results [A. Grunebohm and T. Nishimatsu, Phys. Rev. B 93, 134101 (2016) and Ma et al., Phys. Rev. B 94, 094113 (2016)], but it need to be confirmed by experimental results. In this work, we prepared a 1mol. % Mn-doped Pb(Zr0.2,Ti0.8)O3 ceramics (Pb((Zr0.2,Ti0.8)0.99,Mn0.01)O3), and the electrocaloric effect of the defect-containing ferroelectric ceramics has …
In Situ Monitoring Of Linear Rgd-Peptide Bioconjugation With
Nanoscale Polymer Brushes,
2019
Leibniz Institute of Polymer Research Dresden
In Situ Monitoring Of Linear Rgd-Peptide Bioconjugation With Nanoscale Polymer Brushes, Evmorfia Psarra, Ulla Konig, Martin Muller, Eva Bittrich, Klaus-Jochen Eichhorn, Petra B. Welzel, Manfred Stamm, Petra Uhlmann
Department of Chemistry: Faculty Publications
Bioinspired materials mimicking the native extracellular matrix environment are promising for biotechnological applications. Particularly, modular biosurface engineering based on the functionalization of stimuli-responsive polymer brushes with peptide sequences can be used for the development of smart surfaces with biomimetic cues. The key aspect of this study is the in situ monitoring and analytical verification of the biofunctionalization process on the basis of three complementary analytical techniques. In situ spectroscopic ellipsometry was used to quantify the amount of chemisorbed GRGDS at both the homopolymer poly(acrylic acid) (PAA) brush and the binary poly(N-isopropylacrylamide) (PNIPAAm)− PAA brushes, which was finally confirmed …
Catalytic Mechanism Of Amyloid-Β Peptide Degradation By Insulin Degrading Enzyme: Insights From Qm/Mm Mp2 Calculation,
2019
University of Nebraska - Lincoln
Catalytic Mechanism Of Amyloid-Β Peptide Degradation By Insulin Degrading Enzyme: Insights From Qm/Mm Mp2 Calculation, Rui Lai, Wei-Jen Tang, Hui Li
Department of Chemistry: Faculty Publications
Insulin degrading enzyme (IDE), a metalloprotease that degrades amyloid-β (Aβ) peptides and insulin, is associated with Alzheimer’s disease and diabetes. The mechanism of IDE catalyzed degrading of Aβ peptides, which is of fundamental importance in the design of therapeutic methods for Alzheimer’s disease, has not been fully understood. In this work, combined quantum mechanics and molecular mechanics (QM/MM) style Møller-Plesset second order perturbation theory (MP2) geometry optimization calculations are performed to investigate the catalytic mechanism of the Aβ40 Phe19-Phe20 peptide bond cleavage by human IDE. The analyses using QM/MM MP2 optimization suggest that a …
Molecular Insights Into Organic Particulate
Formation,
2019
University of Nebraska - Lincoln
Molecular Insights Into Organic Particulate Formation, Manoj Kumar, Emily Burrell, Jason C. Hansen, Joseph S. Francisco
Department of Chemistry: Faculty Publications
Carboxylic acids have been detected in particles collected in various regions of the world. Here, we use experiments and Born–Oppenheimer molecular dynamics simulations to better understand the mechanism of particle formation from gas phase mixtures of formic acid (HCOOH), (CH3)3N, and water vapor. A flow reaction cell coupled to two scanning mobility particle sizers has been used to measure particle size, absolute number of particles and kinetics of particle formation. Experimental results show that the addition of (CH3)3N to a mixture of HCOOH and water vapor results in a dramatic increase in …
In-Situ-Investigation Of Enzyme
Immobilization On Polymer Brushes,
2019
Karlsruhe Institute of Technology
In-Situ-Investigation Of Enzyme Immobilization On Polymer Brushes, Meike Koenig, Ulla König, Klaus-Jochen Eichhorn, Martin Muller, Manfred Stamm, Petra Uhlmann
Department of Chemistry: Faculty Publications
Herein, we report on the use of a combined setup of quartz-crystal microbalance, with dissipation monitoring and spectroscopic ellipsometry, to comprehensively investigate the covalent immobilization of an enzyme to a polymer layer. All steps of the covalent reaction of the model enzyme glucose oxidase with the poly(acrylic acid) brush by carbodiimide chemistry, were monitored in-situ. Data were analyzed using optical and viscoelastic modeling. A nearly complete collapse of the polymer chains was found upon activation of the carboxylic acid groups with N-(3-Dimethylaminopropyl)-N′-ethylcarbodiimide and N-Hydroxysuccinimide. The reaction with the amine groups of the enzyme occurs simultaneously with re-hydration of the …
Development Of A Microcolumn One-Site Immunometric Assay For A Protein Biomarker:
Analysis Of Alpha1-Acid Glycoprotein In Serum,
2019
University of Nebraska - Lincoln
Development Of A Microcolumn One-Site Immunometric Assay For A Protein Biomarker: Analysis Of Alpha1-Acid Glycoprotein In Serum, Chenhua Zhang, Shae Lott, William Clarke, David S. Hage
Department of Chemistry: Faculty Publications
A one-site immunometric assay based on affinity microcolumns was developed for the analysis of alpha1-acid glycoprotein (AGP) as a model protein biomarker. In this assay, a sample containing AGP was incubated with an excess amount of a labeled binding agent, such as fluorescein-labeled anti-AGP antibodies or Fab fragments. The excess binding agent was removed by passing this mixture through a microcolumn that contained an immobilized form of AGP, while the signal was measured for the binding agent-AGP complex in the non-retained fraction. Theoretical and practical factors were both considered in selecting the concentration of labeled binding agent, …
Nmr Metabolomics Protocols For Drug Discovery,
2019
University of Nebraska - Lincoln
Nmr Metabolomics Protocols For Drug Discovery, Fatema Bhinderwala, Robert Powers
Department of Chemistry: Faculty Publications
Drug discovery is an extremely difficult and challenging endeavor with a very high failure rate. The task of identifying a drug that is safe, selective and effective is a daunting proposition because disease biology is complex and highly variable across patients. Metabolomics enables the discovery of disease biomarkers, which provides insights into the molecular and metabolic basis of disease and may be used to assess treatment prognosis and outcome. In this regard, metabolomics has evolved to become an important component of the drug discovery process to resolve efficacy and toxicity issues, and as a tool for precision medicine. A detailed …
Reversible Mechanical Deformations Of Soft Microchannel Networks For Sensing In Soft Robotic Systems,
2019
Argonne National Laboratory Lemont & University of Nebraska–Lincoln
Reversible Mechanical Deformations Of Soft Microchannel Networks For Sensing In Soft Robotic Systems, Abhiteja Konda, Donghee Lee, Taesun You, Xiaoyan Wang, Sangjin Ryu, Stephen Morin
Department of Chemistry: Faculty Publications
Microfluidics has enabled numerous applications in, for example, analytical chemistry, medical diagnostics, microelectronics, and soft robotics. In most of these applications, the geometries of the microchannels are of fixed dimensions that (ideally) remain invariant during operation. In soft robotics, however, the geometries of the microchannels contained in soft actuation systems are inherently dynamic, and the specific dimensions are expected to change during operation, and, by extension, the fluid transport properties of the system are variable. If this characteristic is not properly considered, or if methods are not developed to control it, the progress of soft robotic devices with distributed fluid …
Design Of Single-Molecule Multiferroics For Efficient
Ultrahigh-Density Nonvolatile Memories,
2019
Huazhong University of Science and Technology Wuhan
Design Of Single-Molecule Multiferroics For Efficient Ultrahigh-Density Nonvolatile Memories, Qing Yang, Tingting Zhong, Zhengyuan Tu, Lin Zhu, Menghao Wu, Xiao Cheng Zeng
Department of Chemistry: Faculty Publications
It is known that an isolated single-molecule magnet tends to become super- paramagnetic even at an ultralow temperature of a few Kelvin due to the low spin switching barrier. Herein, single-molecule ferroelectrics/multiferroics is proposed, as the ultimate size limit of memory, such that every molecule can store 1 bit data. The primary strategy is to identify polar molecules that possess bistable states, moderate switching barriers, and polarizations fixed along the vertical direction for high-density perpendicular recording. First- principles computation shows that several selected magnetic metal porphyrin molecules possess buckled structures with switchable vertical polarizations that are robust at ambient conditions. …
