bluuebunny/crossref_metadata_2025_split huggingface dataset:
Determination of the natural abundance δ15N of taurine by gas chromatography–isotope ratio measurement mass spectrometry
Authors: Tea Illa , Antheaume Ingrid , Besnard Jorick , Robins Richard J. 
Published: November 2010

AbstractThe measurement of the nitrogen isotope ratio of taurine (2‐aminoethanesulphonic acid) in biological samples has a large number of potential applications. Taurine is a small water‐soluble molecule which is notoriously difficult to analyze due to its polarity and functionality. A method is described which allows the determination of the natural abundance δ15N values of taurine and structural analogues, such as 3‐amino‐1‐propanesulphonic acid (APSA), by isotope ratio mass spectrometry interfaced to gas chromatography (GC‐irm‐MS). The one‐step protocol exploits the simultaneous derivatization of both functionalities of these aminosulphonic acids by reaction with triethylorthoacetate (TEOA). Conditions have been established which ensure quantitative reaction thus avoiding any nitrogen isotope fractionation during derivatization and workup. The differences in the δ15N values of derivatized and non‐derivatized taurine and APSA all fall within the working range of 0.4‰ (−0.02 to 0.39‰). When applied to four sources of taurine with various δ15N values, the method achieved excellent reproducibility and accuracy. The optimized method enables the determination of the natural abundance δ15N values of taurine over the concentration range 1.5–7.84 µmol.mL−1 in samples of biological origin. Copyright © 2010 John Wiley & Sons, Ltd.
Rapid monitoring of sulfur mustard degradation in solution by headspace solid‐phase microextraction sampling and gas chromatography mass spectrometry
Authors: Creek Jo‐Anne M. , McAnoy Andrew M. , Brinkworth Craig S. 
Published: November 2010

AbstractA method using headspace solid‐phase microextraction (HS‐SPME) followed by gas chromatography/mass spectrometry (GC/MS) analysis has been developed to gain insight into the degradation of the chemical warfare agent sulfur mustard in solution. Specifically, the described approach simplifies the sample preparation for GC/MS analysis to provide a rapid determination of changes in sulfur mustard abundance. These results were found to be consistent with those obtained using liquid‐liquid extraction (LLE) GC/MS. The utility of the described approach was further demonstrated by the investigation of the degradation process in a complex matrix with surfactant added to assist solvation of sulfur mustard. A more rapid reduction in sulfur mustard abundance was observed using the HS‐SPME approach with surfactant present and was similar to results from LLE experiments. Significantly, this study demonstrates that HS‐SPME can simplify the sample preparation for GC/MS analysis to monitor changes in sulfur mustard abundance in solution more rapidly, and with less solvent and reagent usage than LLE. Copyright © 2010 Commonwealth of Australia. Published by John Wiley & Sons, Ltd.
Bioassay‐directed fractionation for discovery of bioactive neutral lipids guided by relative mass defect filtering and multiplexed collision‐induced dissociation
Authors: Stagliano Michael C. , DeKeyser Joshua G. , Omiecinski Curtis J. , Jones A. Daniel 
Published: November 2010

AbstractWe report a synergistic method using bioassay‐directed liquid chromatography fractionation and time‐of‐flight mass spectrometry to guide and accelerate bioactive compound discovery. To steer purification and assays toward anticipated neutral lipid activators of a constitutive androstane receptor splice variant, a relative mass defect filter was calculated, based on the ratio of the mass defect to the measured ion mass, and used to reduce the number of candidate ion masses. Mass measurements often lack sufficient accuracy to provide unambiguous assignments of elemental compositions, and since the relative mass defect reflects fractional hydrogen content of ions, this value is largely determined by the hydrogen content of a compound's biosynthetic precursors. A relative mass defect window ranging from 600–1000 ppm, consistent with an assortment of lipids, was chosen to assess the number of candidate ions in fractions of fetal bovine serum. This filter reduced the number of candidate ion m/z values from 1345 to 892, which was further reduced to 21 by intensity and isotope filtering. Accurate mass measurements from time‐of‐flight mass spectrometry and fragment ion masses generated using nonselective collision‐induced dissociation suggested dioctyl phthalate as one of few neutral lipid constituents in the active fraction. The identity of this compound was determined to be di(2‐ethylhexyl) phthalate using GC/MS, and it was ranked as a promising candidate for reporter assay screening. Copyright © 2010 John Wiley & Sons, Ltd.
Empirical equations for the temperature dependence of calcite‐water oxygen isotope fractionation from 10 to 70°C
Authors: Demény Attila , Kele Sándor , Siklósy Zoltán 
Published: November 2010

AbstractAlthough the temperature dependence of calcite‐water oxygen isotope fractionation seems to have been well established by numerous empirical, experimental and theoretical studies, it is still being discussed, especially due to the demand for increased accuracy of paleotemperature calculations. Experimentally determined equations are available and have been verified by theoretical calculations (considered as representative of isotopic equilibrium); however, many natural formations do not seem to follow these relationships implying either that existing fractionation equations should be revised, or that carbonate deposits are seriously affected by kinetic and solution chemistry effects, or late‐stage alterations. In order to test if existing fractionation‐temperature relationships can be used for natural deposits, we have studied calcite formations precipitated in various environments by means of stable isotope mass spectrometry: travertines (freshwater limestones) precipitating from hot and warm waters in open‐air or quasi‐closed environments, as well as cave deposits formed in closed systems. Physical and chemical parameters as well as oxygen isotope composition of water were monitored for all the investigated sites. Measuring precipitation temperatures along with oxygen isotope compositions of waters and calcites yielded empirical environment‐specific fractionation–temperature equations:[1] 1000 · lnα = 17599/T – 29.64 [for travertines with a temperature range of 30 to 70°C] and[2] 1000 · lnα = 17500/T – 29.89 [for cave deposits for the range 10 to 25°C].Finally, based on the comparison of literature data and our results, the use of distinct calcite‐water oxygen isotopic fractionation relationships and application strategies to obtain the most reliable paleoclimate information are evaluated. Copyright © 2010 John Wiley & Sons, Ltd.
Using a dual inlet atmospheric pressure ionization source as a dynamic reaction vessel
Authors: Campbell J. Larry 
Published: November 2010

AbstractAtmospheric pressure ionization (API) sources have the ability to serve as dynamic ‘reaction vessels’ and this capability has been rapidly evolving over the past few years. With API sources, many different reagents and source conditions can be rapidly explored with minimal carryover or contamination of the mass spectrometer. While most API applications involve the simple protonation/deprotonation of analyte molecules, a great deal of flexibility and utility is available in almost any API source, provided the reagents and ionization conditions are judiciously selected. Here, the generation of a unique and useful class of reagent ions at atmospheric pressure is demonstrated for the first time. Within the AP gas‐phase environment of a dual inlet ion source, the gas‐phase synthesis of substituted N‐phenylpyridinium cations is demonstrated by establishing conditions favorable to the nucleophilic substitution reaction required for their formation. The flexibility of this API source as a reaction vessel is also demonstrated. Copyright © 2010 John Wiley & Sons, Ltd.
Structural study of acetogenins by tandem mass spectrometry under high and low collision energy
Authors: Allegrand Julie , Touboul David , Schmitz‐Afonso Isabelle , Guérineau Vincent , Giuliani Alexandre , Le Ven Jessica , Champy Pierre , Laprévote Olivier 
Published: November 2010

AbstractCollision‐induced dissociation experiments of seven annonaceous acetogenins were carried out under high and low collision energy conditions. Each compound was studied as protonated or deprotonated and lithium‐ or sodium‐ cationized molecules, using ElectroSpray Ionisation (ESI) with a hybrid linear trap/orbitrap mass spectrometer (LTQ‐Orbitrap®). The same ion species were studied with a Matrix‐Assisted Laser Desorption Ionisation (MALDI) tandem mass spectrometer in a high collision energy regime (1 or 2 keV). Although each of the techniques showed some limitations in the detection of functional groups, unambiguous structural identification of the acetogenins was obtained. MALDI ToF‐ToF has the advantage over ESI‐based methods to provide mass spectra rich in informative fragments which allows the confirmation of some functional groups position. By contrast, ESI‐LTQ‐Orbitrap® analysis has the advantage over MALDI that the mass spectra are relatively simple with only fragments close to the functional groups. However, this technique needs to carry out experiments both in negative and positive ionization modes. Copyright © 2010 John Wiley & Sons, Ltd.
Diet discrimination factors are inversely related to δ15N and δ13C values of food for fish under controlled conditions
Authors: Dennis Caroline A. , MacNeil M. Aaron , Rosati Jennifer Y. , Pitcher Trevor E. , Fisk Aaron T. 
Published: November 2010

AbstractA recent literature review reported negative relationships between diet discrimination factors (DDFs = Xfish – Xfood; X = δ15N or δ13C) and the values of δ15N and δ13C in the food of wild organisms but there has been no laboratory‐based confirmation of these relationships to date. Laboratory reared guppies (Poecilia reticulata) fed a series of diets with a range of δ13C (−22.9 to −6.6‰) and δ15N (6.5 to 1586‰) values were used to magnify diet‐tissue dynamics in order to calculate DDFs once the fish had achieved equilibrium with each of the diets. Values of DDFs range widely for δ15N (7.1 to −849‰) and δ13C (1.1 to −7.0‰) and showed a strong negative correlation with the stable isotope value in the food for δ15N (slope = −0.59 ± 0.02, r2 = 0.95) and δ13C (slope = −0.56 ± 0.02, r2 = 0.94). Based on these relationships, the magnitude of DDF change over environmentally relevant values of δ15N or δ13C would be significant and could confound the interpretation of stable isotopes in the environment. Using highly enriched experimental diets, our study adds to a growing number of studies that undermine the consistent trophic enrichment paradigm with results that demonstrate the currently poor mechanistic understanding of how DDFs arise. The results of our study highlight that the magnitude of the stable isotope values in prey must be considered when choosing DDF values. Future laboratory studies should therefore be directed at uncovering the mechanistic basis of DDFs and, like others before, we recommend the determination of diet‐dependent DDFs under laboratory conditions before modeling dietary proportions or calculating trophic positions. Copyright © 2010 John Wiley & Sons, Ltd.
Synthesis, characterization and application of modified Pd nanoparticles as preconcentration probes for selective enrichment/analysis of proteins via hydrophobic interactions from real‐world samples using nanoparticle‐liquid‐liquid microextraction coupled to matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry
Authors: Bhat Abdul R. , Wu Hui‐Fen 
Published: November 2010

AbstractWe introduce a novel preconcentrating technique by using surface modification of palladium nanoparticles (Pd‐NPs) with octadecane thiol (ODT) prepared in toluene for selective and sensitive extraction of proteins (insulin, ubiquitin, lysozyme) from a variety of real‐world samples including pancreas, mushroom, soybean and milk using nanoparticle‐liquid‐liquid microextraction (NP‐LLME) coupled to matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry (MALDI‐MS). The limit of detection (LOD) values obtained for gramicidin D and insulin in water and urine are between 17–37 nM (17–37 fmol) (with RSDs ranging from 5.3–7.2%) which are 10–20‐fold enhancement in detection sensitivity compared with conventional MALDI‐MS. The optimal sample pH for highest extraction efficiency of insulin, ubiquitin and lysozyme from biological samples was observed at sample pH ∼ pI which could be due to the enhancement of hydrophobic interactions between proteins with the hydrophobic ligands of Pd‐ODT NPs. In addition, we also found that with the addition of 1 M NaCl, signals could be significantly enhanced by using the current approach. It is an efficient, straightforward, sensitive and selective nanoprobe which can be widely applied for separation, enrichment and preconcentration of peptides or proteins from complex biological samples in proteome research. Copyright © 2010 John Wiley & Sons, Ltd.
Characterization of [peptide+(Ag)n]+ complexes using matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry
Authors: Jayasekharan T. , Sahoo N. K. 
Published: November 2010

AbstractSilver ion complexes of peptides [M + (Ag)n]+, M = angiotensin I or substance P where n = 1–8 and 17–23 for angiotensin I and n = 1–5 for substance P, are identified and characterized using matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry (MALDI‐TOFMS). The Ag+ coordination number exceeds the number of available amino acid residues in angiotensin I whereas the number of observed complexes in substance P is less than the number of amino acid residues in it. The larger coordination number of angiotensin I with Ag+ indicates the simultaneous binding of several Ag+ ions to the amino acid residue present in it. The lower number of observed complexes in substance P suggests the binding of two or more residues to one Ag+ ion. The presence of trifluoroacetic acid in the peptide samples reduces the Ag+ coordination ability in both the peptides which indicates that the basic residues in it are already protonated and do not participate in the Ag+‐binding process. The Ag+ ion also forms a complex with the α‐cyano‐4‐hydroxycinnamic acid (CHCA) matrix and is observed in the MALDI mass spectra and the formation of [CHCA + Ag]+, [CHCA + AgNO3]+ and [(CHCA)2 + Ag]+ ions is due to the high binding affinity of Ag+ to the CN group of CHCA. Copyright © 2010 John Wiley & Sons, Ltd.
An integrated bioanalytical platform for supporting high‐throughput serum protein binding screening
Authors: Zhang Jun , Shou Wilson Z. , Vath Marianne , Kieltyka Kasia , Maloney Jennifer , Elvebak Larry , Stewart Jeremy , Herbst John , Weller Harold N. 
Published: November 2010

AbstractQuantification of small molecules using liquid chromatography/tandem mass spectrometry (LC/MS/MS) on a triple quadrupole mass spectrometer has become a common practice in bioanalytical support of in vitro adsorption, distribution, metabolism and excretion (ADME) screening. The bioanalysis process involves primarily three indispensable steps: MS/MS optimization for a large number of new chemical compounds undergoing various screening assays in early drug discovery, high‐throughput sample analysis with LC/MS/MS for those chemically diverse compounds using the optimized MS/MS conditions, and post‐acquisition data review and reporting. To improve overall efficiency of ADME bioanalysis, an integrated system was proposed featuring an automated and unattended MS/MS optimization, a staggered parallel LC/MS/MS for high‐throughput sample analysis, and a sophisticated software tool for LC/MS/MS raw data review as well as biological data calculation and reporting. The integrated platform has been used in bioanalytical support of a serum protein binding screening assay with high speed, high capacity, and good robustness. In this new platform, a unique sample dilution scheme was also introduced. With this dilution design, the total number of analytical samples was reduced; therefore, the total operation time was reduced and the overall throughput was further improved. The performance of the protein binding screening assay was monitored with two controls representing high and low binding properties and an acceptable inter‐assay consistency was achieved. This platform has been successfully used for the determination of serum protein binding in multiple species for more than 4000 compounds. Copyright © 2010 John Wiley & Sons, Ltd.
Stereo‐based all‐terrain obstacle detection using visual saliency
Authors: Santana Pedro , Guedes Magno , Correia Luís , Barata José 
Published: November 2010

AbstractThis paper proposes a hybridization of two well‐known stereo‐based obstacle detection techniques for all‐terrain environments. While one of the techniques is employed for the detection of large obstacles, the other is used for the detection of small ones. This combination of techniques opportunistically exploits their complementary properties to reduce computation and improve detection accuracy. Being particularly computation intensive and prone to generate a high false‐positive rate in the face of noisy three‐dimensional point clouds, the technique for small obstacle detection is further extended in two directions. The goal of the first extension is to reduce both problems by focusing the detection on those regions of the visual field that detach more from the background and, consequently, are more likely to contain an obstacle. This is attained by means of spatially varying the data density of the input images according to their visual saliency. The second extension refers to the use of a novel voting mechanism, which further improves robustness. Extensive experimental results confirm the ability of the proposed method to robustly detect obstacles up to a range of 20 m on uneven terrain. Moreover, the model runs at 5 Hz on 640 × 480 stereo images. © 2010 Wiley Periodicals, Inc.
A permutation approach to validation*
Authors: Magdon‐Ismail Malik , Mertsalov Konstantin 
Published: November 2010

AbstractWe give a permutation approach to validation (estimation of out‐sample error). One typical use of validation is model selection. We establish the legitimacy of the proposed permutation complexity by proving a uniform bound on the out‐sample error, similar to a Vapnik‐Chervonenkis (VC)‐style bound. We extensively demonstrate this approach experimentally on synthetic data, standard data sets from the UCI‐repository, and a novel diffusion data set. The out‐of‐sample error estimates are comparable to cross validation (CV); yet, the method is more efficient and robust, being less susceptible to overfitting during model selection. Copyright © 2010 Wiley Periodicals, Inc. Statistical Analysis and Data Mining 3: 361‐380 2010
Dynamics of isolatedSaponaria bellidifoliaSm. populations at northern range periphery
Authors: Csergő Anna‐Mária , Molnár Edit , García Maria Begoña 
Published: November 2010

AbstractFour populations ofSaponaria bellidifoliasituated at the species’ northern range periphery (Apuseni Mountains, southeastern Carpathians) were monitored over a period of 5 years. They were chosen to represent different habitat types (rocky, fixed screes, open screes and grassy), disturbance regime (fire), and population sizes (categorized as large and small). The reproductive effort was quantified, and matrix models were used to describe the population dynamics and to assess population viability.Saponaria bellidifoliahad very stable population dynamics in the harsh and stable abiotic conditions of the outcrops where populations occur. Habitat conditions exerted a notable influence on the species’ population reproductive performance, growth rate, and vital rates, whereas population size and climate did not have a clear‐cut effect on the dynamics of the species.Saponaria bellidifoliamaintains viable populations in the southeastern Carpathians, at its northern range periphery.
The Absolute Configurations of Hydroxy Fatty Acids from the Royal Jelly of Honeybees (Apis mellifera)
Authors: Kodai Tetsuya , Nakatani Takafumi , Noda Naoki 
Published: November 2010

Abstract9‐Hydroxy‐2E‐decenoic acid (9‐HDA) is a precursor of the queen‐produced substance, 9‐oxo‐2E‐decenoic acid (9‐ODA), which has various important functions and roles for caste maintenance in honeybee colonies (Apis mellifera). 9‐HDA in royal jelly is considered to be a metabolite of 9‐ODA produced by worker bees, and it is fed back to the queen who then transforms it into 9‐ODA. Recently we found that 9‐HDA is present in royal jelly as a mixture of optical isomers (R:S, 2:1). The finding leads us to suspect that chiral fatty acids in royal jelly are precursors of semiochemicals. Rather than looking for semiochemicals in the mandibular glands of the queen bee, this study involves the search for precursors of pheromones from large quantities of royal jelly. Seven chiral hydroxy fatty acids, 9,10‐dihydroxy‐2E‐decenoic, 4,10‐dihydroxy‐2E‐decenoic, 4,9‐dihydroxy‐2E‐decenoic, 3‐hydroxydecanoic, 3,9‐dihydroxydecanoic, 3,11‐dihydroxydodecanoic, and 3,10‐dihydroxydecanoic acids were isolated. The absolute configurations of these acids were determined using the modified Mosher's method, and it was revealed that, similar to 9‐HDA, five acids are present in royal jelly as mixtures of optical isomers.
Modelling of maize production in Croatia: present and future climate
Authors: VUČETIĆ V. 
Published: November 2010

SUMMARYMaize is one of the most important agricultural crops in Croatia, and was selected for research of the effect of climate warming on yields. The Decision Support System for the Agrotechnology Transfer model (DSSAT) is one of the most utilized crop–weather models in the world, and was used in this paper for the investigation of maize growth and production in the present and future climate. The impact of present climate on maize yield was studied using DSSAT 4.0 with meteorological data from the Zagreb–Maksimir station covering the period 1949–2004. Pedological, physiological and genetic data from a 1999 field maize experiment at the same location were added. The location is representative of the continental climate in central Croatia. The linear trends of model outputs and the non-parametric Mann–Kendall test indicate that the beginning of silking has advanced significantly by 1·4 days/decade since the mid-1990s, and maturity by 4·5 days/decade. It also shows a decrease in biomass by 122 kg/ha and in maize yield by 216 kg/ha in 10 years.Estimates of the sensitivity of maize growth and yield in future climates were made by changing the initial weather and CO2 conditions of the DSSAT 4.0 model according to the different climatic scenarios for Croatia at the end of the 21st century. Changed climate suggests increases in global solar radiation, minimal temperature and maximal temperature (×1·07, 2 and 4°C, respectively), but a decrease in the amount of precipitation (×0·92), compared with weather data from the period 1949–2004. The reduction of maize yield was caused by the increase in minimal and maximal temperature and the decrease in precipitation amount, related to the present climate, is 6, 12 and 3%, respectively. A doubling of CO2 concentration stimulates leaf assimilation, but maize yield is only 1% higher, while global solar radiation growth by 7% increases evapotranspiration by 3%. Simultaneous application of all these climate changes suggested that the maize growth period would shorten by c. 1 month and maize yield would decrease by 9%, with the main reason for maize yield reduction in Croatia being due to extremely warm conditions in the future climate.