Papers by Alexander Aksenov
The effect of the oxido-redn. treatment on the surface properties of the system CeO2-ZrO2 and M2O... more The effect of the oxido-redn. treatment on the surface properties of the system CeO2-ZrO2 and M2O3-CeO2-ZrO2 (M = Y, La) was studied using IR spectroscopy. The presence of various carbonate-carboxylate structures on the surface was demonstrated. The system 10YO1.5-30CeO2-ZrO2 and 10LaO1.5-30CeO2-ZrO2 have such stability that the redox cycle does not cause their removal from the surface. The redn. treatment of the samples leads to reversible redn. of the carbonate structures to carbon monoxide occluded in the pores. The hydroxyl coating of the YO1.5-CeO2-ZrO2 sample was studied by the diffuse reflection IR method. [on SciFinder(R)]
The present disclosure relates to disease detection in plants. In particular, it provides methods... more The present disclosure relates to disease detection in plants. In particular, it provides methods, compns., and devices for the detection of diseases in plants. [on SciFinder(R)]
Medical Applications of Artificial Intelligence, 2013
Journal of breath research, 2015
With ascent to altitude, certain individuals are susceptible to high altitude pulmonary edema (HA... more With ascent to altitude, certain individuals are susceptible to high altitude pulmonary edema (HAPE), which in turn can cause disability and even death. The ability to identify individuals at risk of HAPE prior to ascent is poor. The present study examined the profile of volatile organic compounds (VOC) in exhaled breath condensate (EBC) and pulmonary artery systolic pressures (PASP) before and after exposure to normobaric hypoxia (12% O2) in healthy males with and without a history of HAPE (Hx HAPE, n = 5; Control, n = 11). In addition, hypoxic ventilatory response (HVR), and PASP response to normoxic exercise were also measured. Auto-regression/partial least square regression of whole gas chromatography/mass spectrometry (GC/MS) data and binary logistic regression (BLR) of individual GC peaks and physiologic parameters resulted in models that separate individual subjects into their groups with variable success. The result of BLR analysis highlights HVR, PASP response to hypoxia an...
Analytical Chemistry, 2014
Changing ocean health and the potential impact on marine mammal health are gaining global attenti... more Changing ocean health and the potential impact on marine mammal health are gaining global attention. Direct health assessments of wild marine mammals, however, is inherently difficult. Breath analysis metabolomics is a very attractive assessment tool due to its noninvasive nature, but it is analytically challenging. It has never been attempted in cetaceans for comprehensive metabolite profiling. We have developed a method to reproducibly sample breath from small cetaceans, specifically Atlantic bottlenose dolphins (Tursiops truncatus). We describe the analysis workflow to profile exhaled breath metabolites and provide here a first library of volatile and nonvolatile compounds in cetacean exhaled breath. The described analytical methodology enabled us to document baseline compounds in exhaled breath of healthy animals and to study changes in metabolic content of dolphin breath with regard to a variety of factors. The method of breath analysis may provide a very valuable tool in future wildlife conservation efforts as well as deepen our understanding of marine mammals biology and physiology.
Volatile Biomarkers, 2013
Journal of Breath Research, 2014
Respiratory viral infections such as human rhinovirus (HRV) can lead to substantial morbidity and... more Respiratory viral infections such as human rhinovirus (HRV) can lead to substantial morbidity and mortality, especially in people with underlying lung diseases such as asthma and COPD. One proposed strategy to detect viral infections non-invasively is by volatile organic compound (VOC) assessment via analysis of exhaled breath. The epithelial cells are one of the most important cell lines affected during respiratory infections as they are the first line of pathogen defense. Efforts to discover infection-specific biomarkers can be significantly aided by understanding the VOC emanations of respiratory epithelial cells. Here we test the hypothesis that VOCs obtained from the headspace of respiratory cell culture will differentiate healthy cells from those infected with HRV. Primary human tracheobronchial cells were cultured and placed in a system designed to trap headspace VOCs. HRV-infected cells were compared to uninfected control cells. In addition, cells treated with heat-killed HRV and poly(I:C), a TLR3 agonist, were compared to controls. The headspace was sampled with solid-phase microextraction fibers and VOCs were analyzed by gas chromatography/mass spectrometry. We determined differential expression of compounds such as aliphatic alcohols, branched hydrocarbons, and dimethyl sulfide by the infected cells, VOCs previously associated with oxidative stress and bacterial infection. We saw no major differences between the killed-HRV, poly(I:C), and control cell VOCs. We postulate that these compounds may serve as biomarkers of HRV infection, and that the production of VOCs is not due to TLR3 stimulation but does require active viral replication. Our novel approach may be used for the in vitro study of other important respiratory viruses, and ultimately it may aid in identifying VOC biomarkers of viral infection for point-of-care diagnostics.
Frontiers in Endocrinology, 2013
Diabetes type-2 and the metabolic syndrome are prevalent in epidemic proportions and result in si... more Diabetes type-2 and the metabolic syndrome are prevalent in epidemic proportions and result in significant co-morbid disease. Limitations in understanding of dietary effects and cholesterol metabolism exist. Current methods to assess diabetes are essential, though many are invasive; for example, blood glucose and lipid monitoring require regular finger sticks and blood draws. A novel method to study these diseases may be non-invasive breath testing of exhaled compounds. Currently, acetone and lipid peroxidation products have been seen in small scale studies, though other compounds may be significant. As Atlantic bottlenose dolphins (Tursiops truncatus) have been proposed as a good model for human diabetes, applications of dietary manipulations and breath testing in this population may shed important light on how to design human clinical studies. In addition, ongoing studies indicate that breath testing in dolphins is feasible, humane, and yields relevant metabolites. By studying the metabolic and cholesterol responses of dolphins to dietary modifications, researchers may gain insight into human diabetes, improve the design of costly human clinical trials, and potentially discover biomarkers for non-invasive breath monitoring.
B92. EXHALED BIOMARKERS IN AIRWAYS DISEASES: COMING TO ADULTHOOD, 2010
Journal of Breath Research, 2013
Asthma and chronic obstructive pulmonary disease (COPD) are distinct but clinically overlapping a... more Asthma and chronic obstructive pulmonary disease (COPD) are distinct but clinically overlapping airway disorders which often create diagnostic and therapeutic dilemmas. Current strategies to discriminate these diseases are limited by insensitivity and poor performance due to biologic variability. We tested the hypothesis that a gas chromatograph/differential mobility spectrometer (GC/DMS) sensor could distinguish between clinically well-defined groups with airway disorders based on the volatile organic compounds (VOCs) obtained from exhaled breath. After comparing VOC profiles obtained from 13 asthma, 5 COPD and 13 healthy control subjects, we found that VOC profiles distinguished asthma from healthy controls and also a subgroup of asthmatics taking the drug omalizumab from healthy controls. The VOC profiles could not distinguish between COPD and any of the other groups. Our results show a potential application of the GC/DMS for non-invasive and bedside diagnostics of asthma and asthma therapy monitoring. Future studies will focus on larger sample sizes and patient cohorts.
Frontiers in Ecology and Evolution, 2014
Volatile organic compounds (VOCs) are emitted from all plants and these VOCs are important means ... more Volatile organic compounds (VOCs) are emitted from all plants and these VOCs are important means of communication between plants and insects. It has been documented that pathogen infections alter VOC profiles rendering infected plants more attractive to specific vectors transmitting these pathogens than uninfected plants, thus potentially aiding in pathogen propagation. Mimicking these chemical cues might enable insect attraction away from the plant or disruption of host finding behavior of the vector. However, the practical implications have not been fully explored. We used citrus, Diaphorina citri and huanglongbing (HLB) as a model host-vector-disease system because HLB threatens citrus production worldwide and is similar to other critical diseases of food crops, such as Zebra Chip affecting potato. We formulated a synthetic chemical blend using selected HLB-specific biomarker compounds, and tested the blend with the Attenu assay system for chemosensory proteins. The Attenu assay system is a procedure that identifies interactions between insect chemosensory proteins and their ligands. We found that mixtures of compounds mimicking the volatile profile of HLB-infected citrus can be bound by chemosensory proteins. Further investigation of these blends in laboratory behavioral assays resulted in development of a synthetic lure that was more attractive to D. citri than natural citrus tree volatiles. This strategy could provide a new route to produce chemical lures for vector population control for a variety of plant and/or animal systems and it may result in the development of a practical lure for monitoring vectors of disease, such as D. citri.
International Journal for Ion Mobility Spectrometry, 2009
Ion mobility spectrometry (IMS), using standalone instrumentation and hyphenated with mass spectr... more Ion mobility spectrometry (IMS), using standalone instrumentation and hyphenated with mass spectrometry (IM-MS), has recently undergone significant expansion in the numbers of users and applications, particularly in sectors outside its established user base; predominantly military and security applications. Although several IMS reference standards have been proposed, there are no currently universally recognised reference standards for the calibration and evaluation of mobility spectrometers. This review describes current practices and the literature on chemical standards for validating IMS systems in positive and negative ion modes. The key qualities and requirements an 'ideal' reference standard must possess are defined, together with the instrumental and environmental factors such as temperature, electric field, humidity and drift gas composition that may need to be considered. Important challenges that have yet to be resolved are also identified and proposals for future development presented.
Rapid Communications in Mass Spectrometry, 2010
High-field asymmetric waveform ion mobility spectrometry (FAIMS) is an ion-filtering technique re... more High-field asymmetric waveform ion mobility spectrometry (FAIMS) is an ion-filtering technique recently adapted for use with liquid chromatography/mass spectrometry (LC/MS) to remove interferences during analysis of complex matrices. This is the first systematic study of a series of singly charged tetraalkylammonium ions by FAIMS-MS. The compensation voltage (CV) is the DC offset of the waveform which permits the ion to emerge from FAIMS and it was determined for each member of the series under various conditions. The electrospray ionization conditions explored included spray voltage, vaporizer temperature, and sheath and auxiliary gas pressure. The FAIMS conditions explored included carrier gas flow rate, electrode temperature and composition of the carrier gas. Optimum desolvation was achieved using sufficient carrier gas (flow rate ‡2 L/min) to ensure stable response. Low-mass ions (m/z 100-200) are more susceptible to changes in electrode temperature and gas composition than high mass ions (m/z 200-700). As a result of this study, ions are reliably analyzed using standard FAIMS conditions (dispersion voltage À5000 V, carrier gas flow rate 3 L/min, 50% helium/50%nitrogen, inner electrode temperature 70-C and outer electrode temperature 90-C). Variation of FAIMS conditions may be of great use for the separation of very low mass tetraalkylammonium (TAA) ions from other TAA ions. The FAIMS conditions do not appear to have a major effect on higher mass ions.
Plant Biosystems - An International Journal Dealing with all Aspects of Plant Biology, 2014
Flavescence dorée (FD) is one of the most widely known grapevine yellows disease and one of the m... more Flavescence dorée (FD) is one of the most widely known grapevine yellows disease and one of the most unabated worldwide in the viticulture sector. In this paper, we outline a strategy for developing an integrated system of technologies to enable rapid, early disease FD detection and diagnosis. We propose the deployment of a newly developed sensor device, the differential mobility spectrometer (DMS), which has shown positive results with a similar vector-borne disease in Citrus.
Journal of The American Society for Mass Spectrometry, 2012
Correlation between compensation voltage (CV) and the m/z ratio of singly-charged ions was elucid... more Correlation between compensation voltage (CV) and the m/z ratio of singly-charged ions was elucidated. The experimental data for various alkylammonium homologues and various pharmaceutical compounds were used to construct empirical calibration curves that were fit using commercial regression analysis software packages. The best fit equations were applied to calculate the CV differences (ΔCV) in pure N 2 and N 2 /He 50/50 carrier gasses and CV values for a variety of compounds using only m/z values. The calculated values were in good agreement with experimental data and ΔCV values exhibited a very strong correlation with m/z. Application of these empirical calculations may provide a powerful CV prediction tool for researchers using high-field asymmetric waveform ion mobility spectrometry (FAIMS) and increase the value of FAIMS as an analytical method.
Journal of Organometallic Chemistry, 2007
The reactions of the bis(g 5 -cyclopentadienyl)methylzirconium cation (1) with four imines have b... more The reactions of the bis(g 5 -cyclopentadienyl)methylzirconium cation (1) with four imines have been studied in the gas phase by Fourier transform ion cyclotron resonance mass spectrometry. Reactivity of the bis(g 5 -cyclopentadienyl)methylzirconium cation is governed by the availability of a labile hydrogen in the corresponding imine. The products observed differ from those that might be expected in analogy with earlier work on ketones, aldehydes and alkenes (e.g., zirconocene g 3 -enolate and g 3 -allyl complexes): azomethyne/benzylidene species are found instead of enamines; however, the general reaction mechanism resembles that proposed for ketones and alkenes. An elimination reaction leading to final products was shown to be preceded by a fast migratory insertion/deinsertion equilibrium for alkyl-substituted imines. Such an equilibrium is not possible for aryl-substituted imines due to lack of lability of the aryl groups and thus only methane elimination was observed for these imines.
IOP Conference Series: Materials Science and Engineering, 2011
Gas chromatography/mass spectrometry (GC/MS) is a widely used analytic tool for qualitative and q... more Gas chromatography/mass spectrometry (GC/MS) is a widely used analytic tool for qualitative and quantitative analysis of volatile and semi-volatile compounds. However, GC/MS use is limited by its large size, lack of portability, high cost and inherent complexity. Smaller instruments capable of high-throughput analysis of volatile compounds have the potential of combining MS-like sensitivity with portability. The micromachined differential mobility spectrometer (DMS) is a miniature sensor capable of registering volatile compounds in sub-parts-per-million (ppm) concentrations. It is small, portable, and can be coupled with multiple other compound separation methods. Here we describe paired volatile sample analyses using both GC/MS and GC/DMS which show that the DMS is capable of registering known compounds as verified by MS. Furthermore, we show that MS can be used to help build a library for our unique DMS sensor outputs and detect compounds in chemically complex backgrounds.
ChemBioChem, 2014
Volatile organic compounds (VOCs) emanating from humans have the potential to revolutionize non-i... more Volatile organic compounds (VOCs) emanating from humans have the potential to revolutionize non-invasive diagnostics. Yet, little is known about how these compounds are generated by complex biological systems, and even less is known about how these compounds are reflective of a particular physiological state. In this proof-of-concept study, we examined VOCs produced directly at the cellular level from B lymphoblastoid cells upon infection with three live influenza virus subtypes: H9N2 (avian), H6N2 (avian), and H1N1 (human). Using a single cell line helped to alleviate some of the complexity and variability when studying VOC production by an entire organism, and it allowed us to discern marked differences in VOC production upon infection of the cells. The patterns of VOCs produced in response to infection were unique for each virus subtype, while several other non-specific VOCs were produced after infections with all three strains. Also, there was a specific time course of VOC release post infection. Among emitted VOCs, production of esters and other oxygenated compounds was particularly notable, and these may be attributed to increased oxidative stress resulting from infection. Elucidating VOC signatures that result from the host cells response to infection may yield an avenue for non-invasive diagnostics and therapy of influenza and other viral infections.
ChemBioChem, 2012
This study aimed to determine the concentration of volatile organic compounds (VOCs) and investig... more This study aimed to determine the concentration of volatile organic compounds (VOCs) and investigate the impacts of traffic and industrial activities on the concentration of VOCs near the Central Taiwan Science Park (CTSP) in Taiwan during 2005. Twelve-hour canister sampling
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Papers by Alexander Aksenov
humid ambient storing conditions in refrigerators, eggs can be colonized by fungi and bacteria. Volatile organic
compounds (VOCs) are produced by bacteria and fungi as they proliferate, and these chemicals are emitted back
through the eggshell into the environment. Some of these compounds have low molecular weight and high volatility,
and almost 200 VOCs have been previously identified from contaminated eggs. In this work, we present the study of
metabolites from fungi inside hen eggs and their correlation with the fungi species-specific VOCs. Fresh-eggs(n=2)
and 2months old-eggs(n=4) were stored under normal ambient humid conditions, and they were analyzed using noninvasive
techniques: Solid Phase Microextraction Headspace Gas Chromatography Mass Spectrometry(SPME-HSGC/
MS) and Headspace Gas Chromatography Differential Mobility Spectrometry(HS-GC/DMS). Eggs were placed
inside vials (neck-size-70mm,PTFE-cap,capacity-240ml) that were previously cleaned in a vacuum-oven(160ºC,3h),
and samples were taken after flushing the vials with dryUHP air for 2min. Upon experimetns completion, all eggs
were opened to check fungus presence and identification. DNA was extracted from mycelia of fungal cultures on
APDA, and bacterial colonies that were grown on KB medium. PCR products were sequenced and the fungi and
bacteria were identified using NCBI BLAST results. Petri dishes with grown fungi from eggs were analyzed with
SPME-GC/MS for metabolite confirmation. Almost 100 VOCs have been identified with GC/MS and are classified in
5-groups: fungi (present only in the eggs containing fungi); old (present only in the old eggs that may or may not
contain the fungi); healthy (present only in the eggs not containing the fungi); fresh (present only in the fresh eggs)
and all eggs (present in all eggs). Specific compounds that have been previously attributed to the identified fungi
(Botrytis cinerea and Cladosporium macrocarpum) have been matched with the identified compounds from the fungiinfected
eggs as well as from the analyzed colonies that were grown in vitro in petri-dishes. GC/MS results allow for
clear differentiation between non-infected eggs and eggs infected with fungi. Similarly to GC/MS results,
approximately 100 VOCs that are present in the eggs and absent in the vials with dry air blanks have been identified
in positive ion mode with GC/DMS. Additionally, 4 VOCs have been identified in the negative ion mode. The
advantage of GC/DMS is that it can detect both positive and negative ions in a single measurement, while only one
ion mode could be used at a time in some mass spectrometers . Although chemical identification with GC/DMS
sensor may be not straightforward or not possible, the sensor can be useful as a VOC monitoring tool in production
processes. Visual inspection of tested eggs revealed differences between non-infected eggs and eggs infected with
fungi. Non-invasive sampling of eggs pathogens. GC/DMS chemical signatures to be potentially used in production
process.