bluuebunny/crossref_metadata_2025_split huggingface dataset:
Development of a Stir Bar Sorptive Extraction Method for Analysis of Ochratoxin A in Beer
Authors: Nguyen Kieu T N , Ryu Dojin 
Published: July 2014

Abstract
A new, simple, and sensitive method was developed for extraction of ochratoxin A (OTA) in beer combined with HPLC-fluorescence detector. Samples were extracted by stir bar sorptive extraction (SBSE) followed by liquid desorption using commercially available Twister® EG-Silicone. The main parameters influencing SBSE, including phase ratio, extraction time, stirring speed, ionic strength, organic modifier, pH, temperature, desorption mode, desorption solvent, and desorption time were optimized. Under the optimal conditions, assay was performed on 4 mL of samples acidified at pH 1.5. The samples were extracted for 180 min at a stirring speed of 800 rpm followed by desorption of analyte using 1 mL methanol under sonication for 45 min. The extract was evaporated at 50°C under a gentle nitrogen stream, then redissolved in 200 μL of methanol–water (50 + 50, v/v). After each use, the stir bar was cleaned by sonication in methanol for 30 min three times. The method provided good linearity of the calibration curve with coefficients of determination greater than 0.999. Recoveries of OTA were greater than 83% with RSD lower than 10%, and LOD of OTA in beer was 0.64 ng/L. This method was applied to determine OTA in 19 beer samples. OTA was detected in 12 samples (63%) in the range of 0.01–0.27 ng/mL.
The Accuracy of Vitamin D Assays of Circulating 25-Hydroxyvitamin D Values: Influence of 25-Hydroxylated Ergocalciferol Concentration
Authors: Nguyen Van Thi Quynh , Li Xianjun , Castellanos Karla Josephine , Fantuzzi Giamila , Mazzone Theodore , Braunschweig Carol Arbron 
Published: July 2014

Abstract
Serum samples from 74 obese women were assayed for 25-hydroxyvitamin D [25(OH)D] concentrations using an automated immunoassay [Architect (Abbott)] and ELISA (Alpco Diagnostics), and results were compared with the LC/MS/MS reference method (Quest Diagnostics). The Architect values were significantly lower (mean difference: –13 nmol/L; 95% limits: –54; 28 nmol/L) and the ELISA values were significantly higher (mean difference: 24 nmol/L; 95% limits: –36; 84 nmol/L) than the LC/MS/MS values. The slope of the Passing-Bablok regression line relative to LC/MS/MS was 0.5 [95% confidence interval (CI): 0.41; 0.60] and 1.17 (95% CI: 0.87; 1.56) for Architect and ELISA, respectively, with an intercept of approximately 16 for both assays. Using 50 nmol/L as the cut-point for deficiency, Architect and ELISA misclassified 20 and 27% of the subjects, respectively. In subjects with low circulating 25-hydroxylated ergocalciferol [25(OH)D2] (&lt;10 nmol/L), a Bland-Altman plot and Kappa statistics (Kappa = 0.73; 95% CI: 0.49–0.97) showed good agreement between Architect and LC/MS/MS. However, in subjects with high circulating 25(OH)D2 (≥10 nmol/L), Architect demonstrated poor agreement (Kappa = 0.40; 95% CI: 0.16–0.65). ELISA demonstrated a higher degree of overestimation in women with minimal 25(OH)D2 than those with high 25(OH)D2, suggesting that ELISA overestimates 25-hydroxylated cholecalciferol [25(OH)D3] but underestimates 25(OH)D2.
Determination of Plant Stanols and Plant Sterols in Phytosterol Enriched Foods with a Gas Chromatographic-Flame Ionization Detection Method: NMKL Collaborative Study
Authors: Laakso Päivi H ,   Collaborators:, Sheridan A , Lampi A M , Lacoste F , Janssen H G , Idar Hilde J , van Beek P , Wretling S , Kuechler T 
Published: July 2014

Abstract
This collaborative study with nine participating laboratories was conducted to determine the total plant sterol and/or plant stanol contents in phytosterol fortified foods with a gas chromatographic method. Four practice and 12 test samples representing mainly commercially available foodstuffs were analyzed as known replicates. Twelve samples were enriched with phytosterols, whereas four samples contained only natural contents of phytosterols. The analytical procedure consisted of two alternative approaches: hot saponification method, and acid hydrolysis treatment prior to hot saponification. As a result, sterol/stanol compositions and contents in the samples were measured. The amounts of total plant sterols and total plant stanols varying from 0.005 to 8.04 g/100 g product were statistically evaluated after outliers were eliminated. The repeatability RSD (RSDr) varied from 1.34 to 17.13%. The reproducibility RSD (RSDR) ranged from 3.03 to 17.70%, with HorRat values ranging from 0.8 to 2.1. When only phytosterol enriched food test samples are considered, the RSDr ranged from 1.48 to 6.13%, the RSDR ranged from 3.03 to 7.74%, and HorRat values ranged from 0.8 to 2.1. Based on the results of this collaborative study, the study coordinator concludes the method is fit for its purpose.
Determination of Quaternary Ammonium Compounds in Oranges and Cucumbers Using QuEChERS Extraction and Ultra-Performance Liquid Chromatography/Tandem Mass Spectrometry
Authors: Arrebola-Liébanas Francisco Javier , Abdo María Angeles Herrera , Moreno José Luis Fernandez , Martínez-Vidal José L , Frenich Antonia Garrido 
Published: July 2014

Abstract
A simple and fast method has been developed for determining relevant quaternary ammonium compounds in cucumber and orange samples. The target compounds were benzoalkonium chloride (BAC-10, BAC-12, BAC-14, and BAC-16), didecyldimethylammonium chloride, and benzethonium chloride, all frequently used biocides in the agrifood industry. An extraction based on the buffered Quick, Easy, Cheap, Effective, Rugged, and Safe method and determination by ultra-performance LC/MS/MS that eluted the biocides in less than 5 min were used. The method was fully validated and implemented in a UNE-EN-ISO/IEC 17025 accredited laboratory for its application to the analysis of real samples. Performance characteristics of the method are reported, including an estimation of measurement uncertainty. Calibration curves were set between 0.01 and 0.150 mg/kg, LOD values were always between 0.4 and 1.0 μg/kg, LOQ values were in the range 1–4 μg/kg, recovery was between 81 and 115%, intraday and interday precision were always lower than 17% (expressed as RSD), and expanded uncertainty was always lower than 40%. The validation was accomplished for the two studied matrixes at spiking concentrations of 0.011 and 0.050 mg/kg. The method has been applied to the analysis of 30 cucumber and orange samples that were found to contain concentrations of BAC-12 that ranged between 0.015 and 0.210 mg/kg and of BAC-14 between 0.018 and 0.081 mg/kg.
Selection Based on FOXA2 Expression Is Not Sufficient to Enrich for Dopamine Neurons From Human Pluripotent Stem Cells
Authors: Aguila Julio Cesar , Blak Alexandra , van Arensbergen Joris , Sousa Amaia , Vázquez Nerea , Aduriz Ariane , Gayosso Mayela , Lopez Mato Maria Paz , Lopez de Maturana Rakel , Hedlund Eva , Sonntag Kai-Christian , Sanchez-Pernaute Rosario 
Published: July 2014

Abstract

Human embryonic and induced pluripotent stem cells are potential cell sources for regenerative approaches in Parkinson disease. Inductive differentiation protocols can generate midbrain dopamine neurons but result in heterogeneous cell mixtures. Therefore, selection strategies are necessary to obtain uniform dopamine cell populations. Here, we developed a selection approach using lentivirus vectors to express green fluorescent protein under the promoter region of FOXA2, a transcription factor that is expressed in the floor plate domain that gives rise to dopamine neurons during embryogenesis. We first validated the specificity of the vectors in human cell lines against a promoterless construct. We then selected FOXA2-positive neural progenitors from several human pluripotent stem cell lines, which demonstrated a gene expression profile typical for the ventral domain of the midbrain and floor plate, but failed to enrich for dopamine neurons. To investigate whether this was due to the selection approach, we overexpressed FOXA2 in neural progenitors derived from human pluripotent stem cell lines. FOXA2 forced expression resulted in an increased expression of floor plate but not mature neuronal markers. Furthermore, selection of the FOXA2 overexpressing fraction also failed to enrich for dopamine neurons. Collectively, our results suggest that FOXA2 is not sufficient to induce a dopaminergic fate in this system. On the other hand, our study demonstrates that a combined approach of promoter activation and lentivirus vector technology can be used as a versatile tool for the selection of a defined cell population from a variety of human pluripotent stem cell lines.
Seasonal and interannual changes of the Kuroshio intrusion onto the East China Sea Shelf
Authors: Wu Chau‐Ron , Hsin Yi‐Chia , Chiang Tzu‐Ling , Lin Yong‐Fu , Tsui I‐Fong 
Published: July 2014

AbstractAn advanced artificial neural network classification algorithm is applied to 20 years of multisatellite geostrophic velocity data to study the Kuroshio intrusion onto the southern shelf of the East China Sea. The results suggest that the on‐shelf intrusion may occur year round, but winter intrusion events are more frequent than summer events. Both stronger intrusion (which is closely correlated to surface heat flux gradient) and weaker intrusion (which is correlated to wind forcing) occur during wintertime, but the former dominates in late winter while the latter prevails in early winter. There is a significant year‐to‐year variation of the winter on‐shelf intrusion. Although on‐shelf intrusion is the major characteristic of the region during wintertime, seldom intrusion events have been identified in the winters of 1997–1998 and 2002–2003. Two conditions are responsible for the cause of the nonintrusion events. During the two nonintrusion winters, the upstream Kuroshio transport anomaly is insignificant (the Kuroshio is not weakened) and no significant winter cooling off northeast Taiwan. Thus, the Kuroshio tends to flow along the shelf break following the 200 m isobath and on‐shelf intrusion ceases. Those two nonintrusion events take place during the winters when both the Niño 3.4 index and the PDO index are large and positive.
Anisotropy of magnetic susceptibility in natural olivine single crystals
Authors: Biedermann Andrea R. , Pettke Thomas , Reusser Eric , Hirt Ann M. 
Published: July 2014

AbstractMantle flow dynamics can cause preferential alignment of olivine crystals that results in anisotropy of physical properties. To interpret anisotropy in mantle rocks, it is necessary to understand the anisotropy of olivine single crystals. We determined anisotropy of magnetic susceptibility (AMS) for natural olivine crystals. High‐field AMS allows for the isolation of the anisotropy due to olivine alone. The orientations of the principal susceptibility axes are related to the olivine's crystallographic structure as soon as it contains >3 wt % FeO. The maximum susceptibility is parallel to the c axis both at room temperature (RT) and at 77 K. The orientation of the minimum axis at RT depends on iron content; it is generally parallel to the a axis in crystals with 3–5 wt % FeO, and along b in samples with 6–10 wt % FeO. The AMS ellipsoid is prolate and the standard deviatoric susceptibility, k′, is on the order of 8*10−10 m3/kg for the samples with <1wt % FeO, and ranges from 3.1*10−9 m3/kg to 5.7*10−9 m3/kg for samples with 3–10 wt % FeO. At 77 K, the minimum susceptibility is along b, independent of iron content. The shape of the AMS ellipsoid is prolate for samples with <5 wt % FeO, but can be prolate or oblate for higher iron content. The degree of anisotropy increases at 77 K with p′77 = 7.1 ± 0.5. The results from this study will allow AMS fabrics to be used as a proxy for olivine texture in ultramafic rocks with high olivine content.
The role of wind in the near field and midfield of a river plume
Authors: Kakoulaki Georgia , MacDonald Daniel , Horner‐Devine Alexander R. 
Published: July 2014

AbstractThe role of wind in the near‐field and midfield regions of the Merrimack River plume is quantified using observations from surface drifters released near the river mouth during ebb tide in 2009, 2010, and 2011 under a range of wind and river discharge conditions. Comparison of momentum balance terms and analysis of plume trajectories suggests that the plume is sensitive to wind direction for wind speeds >4 m s−1 in all regions of the plume, including the near field, where wind influence has typically been considered second order. Intermediate ranges (4–12 km) were more strongly influenced by the wind than the near field (0–4 km). However, the influence of the instantaneous wind diminished farther from the mouth, presumably, due to the growing importance of longer time scale process (i.e., Ekman transport). The plume was less sensitive to cross‐shore winds than alongshore winds, particularly near the river mouth, where momentum dominates.
Gas emissions from five volcanoes in northern Chile and implications for the volatiles budget of the Central Volcanic Zone
Authors: Tamburello G. , Hansteen T. H. , Bredemeyer S. , Aiuppa A. , Tassi F. 
Published: July 2014

AbstractThis study performed the first assessment of the volcanic gas output from the Central Volcanic Zone (CVZ) of northern Chile. We present the fluxes and compositions of volcanic gases (H2O, CO2, H2, HCl, HF, and HBr) from five of the most actively degassing volcanoes in this region—Láscar, Lastarria, Putana, Ollagüe, and San Pedro—obtained during field campaigns in 2012 and 2013. The inferred gas plume compositions for Láscar and Lastarria (CO2/Stot = 0.9–2.2; Stot/HCl = 1.4–3.4) are similar to those obtained in the Southern Volcanic Zone of Chile, suggesting uniform magmatic gas fingerprint throughout the Chilean arc. Combining these compositions with our own UV spectroscopy measurements of the SO2 output (summing to ~1800 t d−1 for the CVZ), we calculate a cumulative CO2 output of 1743–1988 t d−1 and a total volatiles output of >20,200 t d−1.
The precipitation of keV energetic oxygen ions at Mars and their effects during the comet Siding Spring approach
Authors: Gronoff Guillaume , Rahmati Ali , Wedlund Cyril Simon , Mertens Christopher J. , Cravens Thomas E. , Kallio Esa 
Published: July 2014

AbstractComet Siding Spring C/2013 A1 will pass Mars on 19 October 2014, entailing particle and dust precipitation in the Martian upper atmosphere and a potential dust hazard for orbiters. An estimate of the flux of energetic O+ ions picked up by the solar wind from the cometary coma is shown, with an increase of the O+ flux above 50 keV by 2 orders of magnitude. While the ionization of Mars' upper atmosphere by precipitating O+ ions is expected to be negligible compared to solar EUV‐XUV ionization, it is of the same order of magnitude at 110 km altitude during the cometary passage, leading to detectable increases in ionospheric densities. Cometary O+ pickup ion precipitation is expected to be the major nightside ionization source, creating a temporary ionosphere and a global airglow. These effects are dependent on the solar and cometary activities at the time of the encounter.
Simulation of substorm‐time acceleration of oxygen ions on azimuthally directed magnetic field lines in the near‐Earth plasma sheet
Authors: Nakayama Y. , Ebihara Y. , Tanaka T. 
Published: July 2014

AbstractAcceleration of energetic ions is one of the drastic and common phenomena in the near‐Earth plasma sheet during the expansion phase of substorms. When a magnetic field line is stretched, the curvature radius of the magnetic field line becomes small, and many of energetic ions are accelerated nonadiabatically under the presence of electric fields. In a global magnetohydrodynamics (MHD) simulation, when the magnetic field line is further stretched, a flux rope structure appears in the near‐Earth plasma sheet (at ~8.5 RE for this particular simulation) for about 10 min before a substorm onset under the presence of the Y component of the interplanetary magnetic field. The magnetic field lines are azimuthally (in the east‐west direction) elongated near the equatorial plane, and the structure is different from that directly associated with magnetic reconnection. Based on a test particle simulation, we show that the oxygen ions departing in the flux rope structure a few minutes before the onset go around in the near‐Earth plasma sheet twice, experience strong dawn‐dusk electric field, and the ions gain kinetic energy as high as ~200 keV in ~10 min. The large acceleration results from nonadiabation motion together with geometry of magnetic field lines having a kink. The acceleration process (passing through or near the kink and energization by dawn‐dusk electric field) is not common. However, most of the particles that are accelerated more than 150 keV passed through or near the kink. The azimuthally elongated magnetic field line seems to have a large influence of substorm‐time acceleration of the oxygen ions that preexist before the onset.
The magnetic structure of Saturn's magnetosheath
Authors: Sulaiman A. H. , Masters A. , Dougherty M. K. , Jia X. 
Published: July 2014

AbstractA planet's magnetosheath extends from downstream of its bow shock up to the magnetopause, where the solar wind flow is deflected around the magnetosphere and the solar wind‐embedded magnetic field lines are draped. This makes the region an important site for plasma turbulence, instabilities, reconnection, and plasma depletion layers. A relatively high Alfvén Mach number solar wind and a polar‐flattened magnetosphere make the magnetosheath of Saturn both physically and geometrically distinct from the Earth's. The polar flattening is predicted to affect the magnetosheath magnetic field structure and thus the solar wind‐magnetosphere interaction. Here we investigate the magnetic field in the magnetosheath with the expectation that polar flattening is manifested in the overall draping pattern. We compare an accumulation of Cassini data between 2004 and 2010 with global magnetohydrodynamic (MHD) simulations and an analytical model representative of a draped field between axisymmetric boundaries. The draping patterns measured are well captured and in broad agreement for given upstream conditions with those of the MHD simulations (which include polar flattening). The deviations from the analytical model, based on no polar flattening, suggest that nonaxisymmetry is invariably a key feature of the magnetosphere's global structure. Our results show a comprehensive overview of the configuration of the magnetic field in a nonaxisymmetric magnetosheath as revealed by Cassini. We anticipate our assessment to provide an insight to this barely studied interface between a high Alfvénic bow shock and a dynamic magnetosphere.
The role of ion‐molecule reactions in the growth of heavy ions in Titan's ionosphere
Authors: Westlake J. H. , Waite J. H. , Carrasco N. , Richard M. , Cravens T. 
Published: July 2014

AbstractThe Ion and Neutral Mass Spectrometer (INMS) and Cassini Plasma Spectrometer (CAPS) have observed Titan's ionospheric composition and structure over several targeted flybys. In this work we study the altitude profiles of the heavy ion population observed by the Cassini Plasma Spectrometer‐Ion Beam Spectrometer (CAPS‐IBS) during the nightside T57 flyby. We produce altitude profiles of heavy ions from the C6–C13 group (Ci indicates the number, i, of heavy atoms in the molecule) using a CAPS‐IBS/INMS cross calibration. These altitude profiles reveal structure that indicates a region of initial formation and growth at altitudes below 1200 km followed by a stagnation and dropoff at the lowest altitudes (1050 km). We suggest that an ion‐molecule reaction pathway could be responsible for the production of the heavy ions, namely reactions that utilize abundant building blocks such as C2H2 and C2H4, which have been shown to be energetically favorable and that have already been identified as ion growth patterns for the lighter ions detected by the INMS. We contrast this growth scenario with alternative growth scenarios determining the implications for the densities of the source heavy neutrals in each scenario. We show that the high‐mass ion density profiles are consistent with ion‐molecule reactions as the primary mechanism for large ion growth. We derive a production rate for benzene from electron recombination of C6H7+ of 2.4 × 10−16 g cm−2 s−1 and a total production rate for large molecules of 7.1 × 10−16 g cm−2 s−1.
Coastal cape and canyon effects on wind‐driven upwelling in northern Taiwan Strait
Authors: Chen Zhaoyun , Yan Xiao‐Hai , Jiang Yuwu 
Published: July 2014

AbstractA combination of observations and numerical model is used to reveal the upwelling features and mechanisms in the northern Taiwan Strait during summer. In situ data give evidence of the upwelling in the form of thermocline tilting upward onshore. The remote sensing data show a strip of upwelling in the coastal region, which occurs more than half a summer. The upwelling probability map indicates there are two upwelling cores, one located downstream of Pingtan Island formed as cape effect and the other over the coastal canyon off the Sansha Bay. Remote sensing data and numerical model results suggest that the southerly wind plays a key role in shaping this upwelling strip, while the tides regulate the upwelling location through tidal mixing effect in the shallow water region, especially lee of Pingtan Island. Further numerical experiments using idealized cape and coastal canyon topography show that vertical velocity is intensified downstream of the cape and canyon. The vorticity equation shows that relative vorticity change along a streamline and frictional diffusion of vorticity are responsible for the vertical velocity off the cape and within and around the canyon. According to the conservation of potential vorticity, the variation of relative vorticity along a streamline over irregular topography, e.g., cape and canyon, is the main mechanism for the two upwelling cores in the northern Taiwan Strait.
New statistical analysis of the horizontal phase velocity distribution of gravity waves observed by airglow imaging
Authors: Matsuda Takashi S. , Nakamura Takuji , Ejiri Mitsumu K. , Tsutsumi Masaki , Shiokawa Kazuo 
Published: July 2014

AbstractWe have developed a new analysis method for obtaining the power spectrum in the horizontal phase velocity domain from airglow intensity image data to study atmospheric gravity waves. This method can deal with extensive amounts of imaging data obtained on different years and at various observation sites without bias caused by different event extraction criteria for the person processing the data. The new method was applied to sodium airglow data obtained in 2011 at Syowa Station (69°S, 40°E), Antarctica. The results were compared with those obtained from a conventional event analysis in which the phase fronts were traced manually in order to estimate horizontal characteristics, such as wavelengths, phase velocities, and wave periods. The horizontal phase velocity of each wave event in the airglow images corresponded closely to a peak in the spectrum. The statistical results of spectral analysis showed an eastward offset of the horizontal phase velocity distribution. This could be interpreted as the existence of wave sources around the stratospheric eastward jet. Similar zonal anisotropy was also seen in the horizontal phase velocity distribution of the gravity waves by the event analysis. Both methods produce similar statistical results about directionality of atmospheric gravity waves. Galactic contamination of the spectrum was examined by calculating the apparent velocity of the stars and found to be limited for phase speeds lower than 30 m/s. In conclusion, our new method is suitable for deriving the horizontal phase velocity characteristics of atmospheric gravity waves from an extensive amount of imaging data.