Product ion distributions for the reactions of NO+ with some N-containing and O-containing heterocyclic compounds obtained using SRI-TOF-MS

Product ion distributions for the reactions of NO+ with nine O-containing and six N-containing heterocyclic compounds present in human volatilome have been determined under the conditions of a Selective Reagent Ionization Time of Flight Mass Spectrometer (SRI-TOF-MS) at E/N values in the drift tube reactor ranging from 90 to 130 Td. This study was undertaken to provide the kinetics data by which these heterocyclic compounds could be analyzed in biogenic media using SRI-TOF-MS. The specific heterocyclic compounds are furan, 2-methylfuran, 3-methylfuran, 2,5-dimethylfuran, 2-pentylfuran, 2,3-dihydrofuran, 1,3-dioxolane, 2-methyl-1,3-dioxolane, γ-butyrolactone, pyrrole, 1-methylpyrrole, pyridine, 2,6-dimethylpyridine, pyrimidine, and 4-methylpyrimidine. Charge transfer was the dominant mechanism in the majority of these NO+ reactions generating the respective M+ parent cation, but in the pyridine, pyrimidine, and 4-methylpyrimidine reactions, stable NO+M adduct ions were the major products with M+ ions as minor products. The reactions of dioxolanes with NO+ proceeded by hydride ion transfer only producing (M−H)+ ions. Fragmentation of the excited nascent product ions (M+)* did not occur for the majority of these reactions under the particular chosen conditions of the SRI-TOF-MS reactor, but partial fragmentation did occur in the 2,3-dihydrofuran and 2-pentylfuran reactions. However, lowering of the E/N in the drift tube suppresses fragmentation of (M+)* ions and promotes the formation of NO+M adduct ions, whereas increasing E/N has the opposite effect, as expected. The product ion distributions were seen to be independent of the humidity of the sample gas

Product ion distributions for the reactions of NO(+) with some physiologically significant aldehydes obtained using a SRI-TOF-MS instrument

Product ion distributions for the reactions of NO(+) with 22 aldehydes involved in human physiology have been determined under the prevailing conditions of a selective reagent ionization time of flight mass spectrometry (SRI-TOF-MS) at an E/N in the flow/drift tube reactor of 130 Td. The chosen aldehydes were fourteen alkanals (the C2-C11 n-alkanals, 2-methyl propanal, 2-methyl butanal, 3-methyl butanal, and 2-ethyl hexanal), six alkenals (2-propenal, 2-methyl 2-propenal, 2-butenal, 3-methyl 2-butenal, 2-methyl 2-butenal, and 2-undecenal), benzaldehyde, and furfural. The product ion fragmentations patterns were determined for both dry air and humid air (3.5% absolute humidity) used as the matrix buffer/carrier gas in the drift tube of the SRI-TOF-MS instrument. Hydride ion transfer was seen to be a common ionization mechanism in all these aldehydes, thus generating (M-H)(+) ions. Small fractions of the adduct ion, NO(+)M, were also seen for some of the unsaturated alkenals, in particular 2-undecenal, and heterocyclic furfural for which the major reactive channel was non-dissociative charge transfer generating the M(+) parent ion. Almost all of the reactions resulted in partial fragmentation of the aldehyde molecules generating hydrocarbon ions; specifically, the alkanal reactions resulted in multiple product ions, whereas, the alkenals reactions produced only two or three product ions, dissociation of the nascent excited product ion occurring preferentially at the 2-position. The findings of this study are of particular importance for data interpretation in studies of aldehydes reactions employing SRI-TOF-MS in the NO(+) mode

Algebro-Geometric Solutions of the Boussinesq Hierarchy

We continue a recently developed systematic approach to the Bousinesq (Bsq) hierarchy and its algebro-geometric solutions. Our formalism includes a recursive construction of Lax pairs and establishes associated Burchnall-Chaundy curves, Baker-Akhiezer functions and Dubrovin-type equations for analogs of Dirichlet and Neumann divisors. The principal aim of this paper is a detailed theta function representation of all algebro-geometric quasi-periodic solutions and related quantities of the Bsq hierarchy.Comment: LaTeX, 48 page

The inverse resonance problem for perturbations of algebro-geometric potentials

We prove that a compactly supported perturbation of a rational or simply periodic algebro-geometric potential of the one-dimensional Schr\"odinger equation on the half line is uniquely determined by the location of its Dirichlet eigenvalues and resonances.Comment: 14 page

Elliptic Solitons and Groebner Bases

We consider the solution of spectral problems with elliptic coefficients in the framework of the Hermite ansatz. We show that the search for exactly solvable potentials and their spectral characteristics is reduced to a system of polynomial equations solvable by the Gr\"obner bases method and others. New integrable potentials and corresponding solutions of the Sawada-Kotera, Kaup-Kupershmidt, Boussinesq equations and others are found.Comment: 18 pages, no figures, LaTeX'2

Dirofilaria spp. And angiostrongylus vasorum: Current risk of spreading in central and northern europe

In the past few decades, the relevance of Dirofilaria immitis and Dirofilaria repens, causing cardiopulmonary and subcutaneous dirofilariosis in dogs and cats, and of Angiostrongylus vasorum, causing canine angiostrongylosis, has steadily increased in Central and Northern Europe. In this review, a summary of published articles and additional reports dealing with imported or autoch-thonous cases of these parasites is provided for Central (Austria, Czechia, Germany, Hungary, Lux-emburg, Poland, Slovakia, Slovenia, and Switzerland) and Northern (Denmark, Finland, Iceland, Norway, and Sweden) Europe. Research efforts focusing on Dirofilaria spp. and A. vasorum have varied by country, and cross-border studies are few. The housing conditions of dogs, pet move-ments, the spread of competent vectors, and climate change are important factors in the spread of these nematodes. Dogs kept outside overnight are a major factor for the establishment of Dirofilaria spp. However, the establishment of invasive, diurnal, synanthropic, competent mosquito vectors such as Aedes albopictus may also influence the establishment of Dirofilaria spp. The drivers of the spread of A. vasorum remain not fully understood, but it seems to be influenced by habitats shared with wild canids, dog relocation, and possibly climatic changes; its pattern of spreading appears to be similar in different countries. Both Dirofilaria spp. and A. vasorum merit further monitoring and research focus in Europe

The role of mathematical modeling in VOC analysis using isoprene as a prototypic example

Isoprene is one of the most abundant endogenous volatile organic compounds (VOCs) contained in human breath and is considered to be a potentially useful biomarker for diagnostic and monitoring purposes. However, neither the exact biochemical origin of isoprene nor its physiological role are understood in sufficient depth, thus hindering the validation of breath isoprene tests in clinical routine. Exhaled isoprene concentrations are reported to change under different clinical and physiological conditions, especially in response to enhanced cardiovascular and respiratory activity. Investigating isoprene exhalation kinetics under dynamical exercise helps to gather the relevant experimental information for understanding the gas exchange phenomena associated with this important VOC. A first model for isoprene in exhaled breath has been developed by our research group. In the present paper, we aim at giving a concise overview of this model and describe its role in providing supportive evidence for a peripheral (extrahepatic) source of isoprene. In this sense, the results presented here may enable a new perspective on the biochemical processes governing isoprene formation in the human body.Comment: 17 page

Isoprene and acetone concentration profiles during exercise on an ergometer

A real-time recording setup combining exhaled breath VOC measurements by proton transfer reaction mass spectrometry (PTR-MS) with hemodynamic and respiratory data is presented. Continuous automatic sampling of exhaled breath is implemented on the basis of measured respiratory flow: a flow-controlled shutter mechanism guarantees that only end-tidal exhalation segments are drawn into the mass spectrometer for analysis. Exhaled breath concentration profiles of two prototypic compounds, isoprene and acetone, during several exercise regimes were acquired, reaffirming and complementing earlier experimental findings regarding the dynamic response of these compounds reported by Senthilmohan et al. [1] and Karl et al. [2]. While isoprene tends to react very sensitively to changes in pulmonary ventilation and perfusion due to its lipophilic behavior and low Henry constant, hydrophilic acetone shows a rather stable behavior. Characteristic (median) values for breath isoprene concentration and molar flow, i.e., the amount of isoprene exhaled per minute are 100 ppb and 29 nmol/min, respectively, with some intra-individual day-to-day variation. At the onset of exercise breath isoprene concentration increases drastically, usually by a factor of ~3-4 within about one minute. Due to a simultaneous increase in ventilation, the associated rise in molar flow is even more pronounced, leading to a ratio between peak molar flow and molar flow at rest of ~11. Our setup holds great potential in capturing continuous dynamics of non-polar, low-soluble VOCs over a wide measurement range with simultaneous appraisal of decisive physiological factors affecting exhalation kinetics.Comment: 35 page