Development, characterization, and application of flowing atmospheric-pressure afterglow ionization for mass spectrometric analysis of ambient organic aerosols

Addressing current limitations of state-of-the-art instrumentation in aerosol research, the aim of this work was to explore and assess the applicability of a novel soft ionization technique, namely flowing atmospheric-pressure afterglow (FAPA), for the mass spectrometric analysis of airborne particulate organic matter. Among other soft ionization methods, the FAPA ionization technique was developed in the last decade during the advent of ambient desorption/ionization mass spectrometry (ADI–MS). Based on a helium glow discharge plasma at atmospheric-pressure, excited helium species and primary reagent ions are generated which exit the discharge region through a capillary electrode, forming the so-called afterglow region where desorption and ionization of the analytes occurs. Commonly, fragmentation of the analytes during ionization is reported to occur only to a minimum extent, predominantly resulting in the formation of quasimolecular ions, i.e. [M+H]+ and [M–H]– in the positive and the negative ion mode, respectively. Thus, identification and detection of signals and their corresponding compounds is facilitated in the acquired mass spectra. The focus of the first part of this study lies on the application, characterization and assessment of FAPA–MS in the offline mode, i.e. desorption and ionization of the analytes from surfaces. Experiments in both positive and negative ion mode revealed ionization patterns for a variety of compound classes comprising alkanes, alcohols, aldehydes, ketones, carboxylic acids, organic peroxides, and alkaloids. Besides the always emphasized detection of quasimolecular ions, a broad range of signals for adducts and losses was found. Additionally, the capabilities and limitations of the technique were studied in three proof-of-principle applications. In general, the method showed to be best suited for polar analytes with high volatilities and low molecular weights, ideally containing nitrogen- and/or oxygen functionalities. However, for compounds with low vapor pressures, containing long carbon chains and/or high molecular weights, desorption and ionization is in direct competition with oxidation of the analytes, leading to the formation of adducts and oxidation products which impede a clear signal assignment in the acquired mass spectra. Nonetheless, FAPA–MS showed to be capable of detecting and identifying common limonene oxidation products in secondary OA (SOA) particles on a filter sample and, thus, is considered a suitable method for offline analysis of OA particles. In the second as well as the subsequent parts, FAPA–MS was applied online, i.e. for real time analysis of OA particles suspended in air. Therefore, the acronym AeroFAPA–MS (i.e. Aerosol FAPA–MS) was chosen to refer to this method. After optimization and characterization, the method was used to measure a range of model compounds and to evaluate typical ionization patterns in the positive and the negative ion mode. In addition, results from laboratory studies as well as from a field campaign in Central Europe (F–BEACh 2014) are presented and discussed. During the F–BEACh campaign AeroFAPA–MS was used in combination with complementary MS techniques, giving a comprehensive characterization of the sampled OA particles. For example, several common SOA marker compounds were identified in real time by MSn experiments, indicating that photochemically aged SOA particles were present during the campaign period. Moreover, AeroFAPA–MS was capable of detecting highly oxidized sulfur-containing compounds in the particle phase, presenting the first real-time measurements of this compound class. Further comparisons with data from other aerosol and gas-phase measurements suggest that both particulate sulfate as well as highly oxidized peroxyradicals in the gas phase might play a role during formation of these species. Besides applying AeroFAPA–MS for the analysis of aerosol particles, desorption processes of particles in the afterglow region were investigated in order to gain a more detailed understanding of the method. While during the previous measurements aerosol particles were pre-evaporated prior to AeroFAPA–MS analysis, in this part no external heat source was applied. Particle size distribution measurements before and after the AeroFAPA source revealed that only an interfacial layer of OA particles is desorbed and, thus, chemically characterized. For particles with initial diameters of 112 nm, desorption radii of 2.5–36.6 nm were found at discharge currents of 15–55 mA from these measurements. In addition, the method was applied for the analysis of laboratory-generated core-shell particles in a proof-of-principle study. As expected, predominantly compounds residing in the shell of the particles were desorbed and ionized with increasing probing depths, suggesting that AeroFAPA–MS might represent a promising technique for depth profiling of OA particles in future studies.

Synthesis of (-)-dactylolide and 13-desmethylene-(-)-dactylolide and their effects on tubulin

An efficient new synthesis has been elaborated for non-natural (-)-dactylolide ((-)-2) and its 13-desmethylene analogue 4, employing a HWE-based macrocyclization approach with beta-keto-phosphonate/aldehyde 19 and the respective 13-desmethylene derivative as the key intermediates. Both (-)-2 and 4 as well as the corresponding C20 alcohols inhibit human cancer cell proliferation with IC(50) values in the sub-micromolar range and induce the polymerization of tubulin in vitro.

Numerical investigation of effects of addition of ethanol to gasoline on Laminar Flame Speed (LFS), autoignition, and wall quenching

Since the advent of automobiles, alcohol has been considered a possible engine fuel1,2. With the recent increased concern about the high price of crude oil due to fluctuating supply and demand and environmental issues, interest in alcohol based fuels has increased2,3. However, using pure alcohols or blends with conventional fuels in high percentages requires changes to the engine and fuel system design2. This leads to the need for a simple and accurate conventional fuels-alcohol blends combustion models that can be used in developing parametric burn rate and knock combustion models for designing more efficient Spark Ignited (SI) engines. To contribute to this understanding, numerical simulations were performed to obtain detailed characteristics of Gasoline-Ethanol blends with respect to Laminar Flame Speed (LFS), autoignition and Flame-Wall interactions. The one-dimensional premixed flame code CHEMKIN® was applied to simulate the burning velocity and autoignition characteristics using the freely propagating model and closed homogeneous reactor model respectively. Computational Fluid Dynamics (CFD) was used to obtain detailed flow, temperature, and species fields for Flame-wall interactions. A semi-detailed validated chemical kinetic model for a gasoline surrogate fuel developed by Andrae and Head4 was used for the study of LFS and Autoignition. For the quenching study, a skeletal chemical kinetic mechanism of gasoline surrogate, having 50 species and 174 reactions was used. The surrogate fuel was defined as a mixture of pure n-heptane, isooctane, and toluene. For LFS study, the ethanol volume fraction was varied from 0 to 85%, initial pressure from 4 to 8 bar, initial temperature from 300 to 900K, and dilution from 0 to 32%. Whereas for Autoignition study, the ethanol volume fraction was varied between 0 to 85%, initial pressure was varied between 20 to 60 bar, initial temperature was varied between 800 to 1200K, and the dilution was varied between 0 to 32% at equivalence ratios of 0.5, 1.0 and 1.5 to represent the in-cylinder conditions of a SI engine. For quenching study three Ethanol blends, namely E0, E25 and E85 are described in detail at an initial pressure of 8 atm and 17 atm. Initial wall temperature was taken to be 400 K. Quenching thicknesses and heat fluxes to the wall were computed. The laminar flame speed was found to increase with ethanol concentration and temperature but decrease with pressure and dilution. The autoignition time was found to increase with ethanol concentration at lower temperatures but was found to decrease marginally at higher temperatures. The autoignition time was also found to decrease with pressure and equivalence ratio but increase with dilution. The average quenching thickness was found to decrease with an increase in Ethanol concentration in the blend. Heat flux to the wall increased with increase in ethanol percentage in the blend and at higher initial pressures. Whereas the wall heat flux decreased with an increase in dilution. Unburned Hydrocarbon (UHC) and CO % was also found to decrease with ethanol concentration in the blend.

Advanced Nanostructured Electro-Catalysts for Electricity Generation and Biorenewable Alcohol Conversion

In my Ph.D research, a wet chemistry-based organic solution phase reduction method was developed, and was successfully applied in the preparation of a series of advanced electro-catalysts, including 0-dimensional (0-D) Pt, Pd, Au, and Pd-Ni nanoparticles (NPs), 1-D Pt-Fe nanowires (NWs) and 2-D Pd-Fe nanoleaves (NLs), with controlled size, shape, and morphology. These nanostructured catalysts have demonstrated unique electro-catalytic functions towards electricity production and biorenewable alcohol conversion. The molecular oxygen reduction reaction (ORR) is a long-standing scientific issue for fuel cells due to its sluggish kinetics and the poor catalyst durability. The activity and durability of an electro-catalyst is strongly related with its composition and structure. Based on this point, Pt-Fe NWs with a diameter of 2 - 3 nm were accurately prepared. They have demonstrated a high durability in sulfuric acid due to its 1-D structure, as well as a high ORR activity attributed to its tuned electronic structure. By substituting Pt with Pd using a similar synthesis route, Pd-Fe NLs were prepared and demonstrated a higher ORR activity than Pt and Pd NPs catalysts in the alkaline electrolyte. Recently, biomass-derived alcohols have attracted enormous attention as promising fuels (to replace H2) for low-temperature fuel cells. From this point of view, Pd-Ni NPs were prepared and demonstrated a high electro-catalytic activity towards ethanol oxidation. Comparing to ethanol, the biodiesel waste glycerol is more promising due to its low price and high reactivity. Glycerol (and crude glycerol) was successfully applied as the fuel in an Au-anode anion-exchange membrane fuel cell (AEMFC). By replacing Au with a more active Pt catalyst, simultaneous generation of both high power-density electricity and value-added chemicals (glycerate, tartronate, and mesoxalate) from glycerol was achieved in an AEMFC. To investigate the production of valuable chemicals from glycerol electro-oxidation, two anion-exchange membrane electro-catalytic reactors were designed. The research shows that the electro-oxidation product distribution is strongly dependent on the anode applied potential. Reaction pathways for the electro-oxidation of glycerol on Au/C catalyst have been elucidated: continuous oxidation of OH groups (to produce tartronate and mesoxalate) is predominant at lower potentials, while C-C cleavage (to produce glycolate) is the dominant reaction path at higher potentials.

Looking at Chemistry in Hard to See Places: Understanding Energy Conversion at 1400° Celsius

Solid oxide fuel cells (SOFCs) are promising devices for stationary and portable power and heat generation, because they can use complex fuels such as hydro-carbons, CO, and alcohols. Extreme, non-equilibrium conditions and high tem-peratures (≥ 700 ˚C) required for SOFC operation hamper efforts to understand the mechanisms of component degradation in SOFCs. This talk focuses on new insights into SOFC chemistry and the conversion of carbon-containing fuels (both hydrocarbons and oxygenated) into electricity, carbon dioxide and water, gleaned from a combination of techniques including electrochemical impedance spectroscopy, voltammetry, and vibrational Raman scattering.

Stereoselectivity of Additions to N-Methyl Acetonitrilium Fluorosulfonate

Alkoxy-N-methyl-acetiminium salts were prepared by addition of CH3OH and C2H5OH to N-methyl acetonitrilium fluorosulfonate at low temperature. Analysis of the (5)J(HH) and (3)J(13)C-H coupling constants in the NMR spectra showed an anti addition with a diastereoselectivity of >9596. Deprotonation of these salts with (Z)-configuration gave the corresponding N-methyl-alkoxyacetimines with very high (E)-configuration. Upon protonation at -78 degrees C, these iminoesters gave the corresponding alkoxy-N-methyl-acetirninium salts with (E)-configuration. Computational analyses of the iminoesters and the corresponding iminium cations including the conformations give insight into the relative stability. Nitrilium salts can be used as reagents, exemplified by some esterifications between simple acids and alcohols.

1,2-Bis(2-benzimidazolyl)-1,2-ethanediol, a chiral, tridentate, facially coordinating ligand

The ligand 1,2-bis(1H-benzimidazol-2-yl)-1,2-ethanediol, 1, and its methylated derivative 2 are readily synthesized from tartaric acid, and act as chiral, facially coordinating tridentate ligands, forming complexes of composition ML2 with octahedral transition metals. The copper(II) complexes show distorted 4 + 2 coordination with benzimidazoles occupying the equatorial sites and alcohol functions weakly binding in the axial sites. Nickel(II) complexes in three different states of protonation show regular octahedral geometry with the alcohols mutually cis. Deprotonation of the coordinated alcohol produces little structural change but the monodeprotonated complex forms a hydrogen bonded dimer. Magnetic measurements show the hydrogen bonded bridge to offer a pathway for weak antiferromagnetic coupling. UV-Visible spectroscopy shows the ligand to have a field intermediate between water and pyridine. The diastereoselectivity of complexation depends on the geometry: nickel(II) shows a weak preference for the homochiral complex, whereas copper(II) forms almost exclusively homochiral complexes.

Proceedings of the Twentieth Annual Biochemical Engineering Symposium

The 20th Annual Biochemical Engineering Symposium was held at Kansas State University on April 21,1990. The objectives of the symposium were to provide: (i) a forum for informal discussion of biochemical engineering research being conducted at the participating institutions and (ii) an opportunity for students to present and publish their work. Twenty-eight papers presented at the symposium are included in this proceedings. Some of the papers describe the progress of ongoing projects, and others contain the results of completed projects. Only brief summaries are given of the papers that will be published in full elsewhere. The program of the symposium and a list of the participants are included in the proceedings. ContentsCell Separations and Recycle Using an Inclined Settler, Ching-Yuan Lee, Robert H. Davis and Robert A. Sclafani Micromixing and Metabolism in Bioreactors: Characterization of a 14 L Fermenter, K.S. Wenger and E.H. Dunlop Production, Purification, and Hydrolysis Kinetics of Wild-Type and Mutant Glucoamylases from Aspergillus Awamori, Ufuk Bakir, Paul D. Oates, Hsiu-Mei Chen and Peter J. Reilly Dynamic Modeling of the Immune System, Barry Vant-Hull and Dhinakar S. Kompala Dynamic Modeling of Active Transport Across a Biological Cell: A Stochastic Approach, B.C. Shen, S.T. Chou, Y.Y. Chiu and L.T. Fan Electrokinetic Isolation of Bacterial Vesicles and Ribosomes, Debra T.L. Hawker, Robert H. Davis, Paul W. Todd, and Robert Lawson Application of Dynamic Programming for Fermentative Ethanol Production by Zymomonas mobilis, Sheyla L. Rivera and M. Nazmul Karim Biodegradation of PCP by Pseudomonas cepacia, R. Rayavarapu, S.K. Banerji, and R.K. Bajpai Modeling the Bioremediation of Contaminated Soil Aggregates: a Phenomenological Approach, S. Dhawan, L.E. Erickson and L.T. Fan Biospecific Adsorption of Glucoamylase-I from Aspergillus niger on Raw Starch, Bipin K. Dalmia and Zivko L. Nikolov Overexpression in Recombinant Mammalian Cells: Effect on Growth Rate and Genetic Instability, Jeffrey A. Kern and Dhinakar S. Kompala Structured Mathematical Modeling of Xylose Fermentation, A.K. Hilaly, M.N. Karim, I. C. Linden and S. Lastick A New Culture Medium for Carbon-limited Growth of Bacillus thuringiensis, W. -M. Liu and R.K. Bajpai Determination of Sugars and Sugar Alcohols by High Performance Ion Chromatography, T. J. Paskach, H.-P. Lieker, P.J. Reilly, and K. Thielecke Characterization of Poly-Asp Tailed B-Galactosidase, M.Q. Niederauer, C.E. Glatz, l.A. Suominen, C.F. Ford, and M.A. Rougvie Computation of Conformations and Energies of cr-Glucosyl Disaccharides, Jing Zepg, Michael K. Dowd, and Peter J. Reilly Pentachlorophenol Interactions with Soil, Shein-Ming Wei, Shankha K. Banerji, and Rakesh K. Bajpai Oxygen Transfer to Viscous Liquid Media in Three-Phase Fluidized Beds of Floating Bubble Freakers, Y. Kang, L.T. Fan, B.T. Min and S.D. Kim Studies on the Invitro Development of Chick Embryo, A. Venkatraman and T. Panda The Evolution of a Silicone Based Phase-Separated Gravity-Independent Bioreactor, Peter E. Villeneuve and Eric H. Dunlop Biodegradation of Diethyl Phthalate, Guorong Zhang, Kenneth F. Reardon and Vincent G. Murphy Microcosm Treatability of Soil Contaminated with Petroleum Hydrocarbons, P. Tuitemwong, S. Dhawan, B.M. Sly, L.E. Erickson and J.R. Schlup

Lipids and nitrogen isotopes of deep-water corals

The lipid and organic nitrogen isotopic (delta15N) compositions of two common deep-water corals (Lophelia pertusa and Madrepora oculata) collected from selected locations of the NE Atlantic are compared to the composition of suspended particulate organic matter, in order to determine their principle food source. Initial results suggest that they may feed primarily on zooplankton. This is based on the increased abundances of mono-unsaturated fatty acids and alcohols and the different ratios of the polyunsaturated fatty acids, 22:6/20:5 of the corals when compared to those of the suspended particulate organic matter. There is enrichment in L. pertusa of mono-unsaturated fatty acids and of delta15N relative to M. oculata. It is unclear whether this reflects different feeding strategies or assimilation/storage efficiencies of zooplankton tissue or different metabolism in the two coral species.

Geochemical parameters of sediments and water of the Black Sea, data of Cruise 8 of R/V Vityaz-2

The book presents results of comprehensive geological investigations carried out during Cruise 8 of R/V "Vityaz-2" to the western part of the Black Sea in 1984. Systematic studies in the Black Sea during about hundred years have not weakened interest in the sea. Lithological and geochemical studies of sediments in estuarine areas of the Danube and the Kyzyl-Irmak rivers, as well as in adjacent parts of the deep sea and some other areas were the main aims of the cruise. Data on morphological structures of river fans, lithologic and chemical compositions of sediments in the fans and their areal distribution, forms of occurrence of chemical elements, role of organic matter and gases in sedimentation and diagenesis are given and discussed in the book.