bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ionospheric total electron contents (TECs) as indicators of solar EUV changes during the last two solar minima
Authors: Didkovsky Leonid , Wieman Seth 
Published: May 2014

AbstractDuring the extended solar minimum from 2007 to 2009 anomalously low densities were observed in the Earth's thermosphere. Solar activity for the minimum of Solar Cycles 23 and 24 was lower than for Solar Cycles 22 and 23. However, a comparison of global daily averaged Total Electron Content (TEC) for these two solar minima does not show any significant difference. Why these significant changes between the 2008 and 1996 minima were observed in the He II EUV absolute irradiance and not in the global TEC for which EUV irradiance is one of the primary drivers is not well understood and may be interpreted as an effect of EUV instrument degradation. In this study, we analyze TEC data from 1995 to 2013 from the Center for Orbit Determination in Europe (CODE) database and compare global daily averaged TEC signal with TEC sectorial spherical harmonics which reflect a narrower temporal and spatial integration of the TEC in the Earth's ionosphere. Our analyses of both TEC data and errors show significant decreases of sectorial TECs for the 2008 and 2009 minimum compared to the minimum of 1996. We also compare the most recent version of Solar and Heliospheric Observatory/Solar EUV Monitor (SOHO/SEM) He II absolute EUV irradiance with the measurements from the Solar Dynamics Observatory/Extreme Ultraviolet Variability Experiment channels. This comparison shows that the EUV He II irradiance was about 12 ± 4% lower for the minimum of 2008 and 2009 compared to the minimum of 1996 when a low‐pass filter with a 365 day window was used.
An Aluminophosphate Molecular Sieve with 36 Crystallographically Distinct Tetrahedral Sites
Authors: Lee Jun Kyu , Turrina Alessandro , Zhu Liangkui , Seo Seungwan , Zhang Daliang , Cox Paul A. , Wright Paul A. , Qiu Shilun , Hong Suk Bong 
Published: May 2014

AbstractThe structure of the new medium‐pore aluminophosphate molecular sieve PST‐6 is determined by the combined use of rotation electron diffraction tomography, synchrotron X‐ray powder diffraction, and computer modeling. PST‐6 was prepared by calcination of another new aluminophosphate material with an unknown structure synthesized using diethylamine as a structure‐directing agent, which is thought to contain bridging hydroxy groups. PST‐6 has 36 crystallographically distinct tetrahedral sites in the asymmetric unit and is thus crystallographically the most complex zeolitic structure ever solved.
The Biosynthesis and Catabolism of the Maleic Anhydride Moiety of Stipitatonic Acid
Authors: al Fahad Ahmed , Abood Amira , Simpson Thomas J. , Cox Russell J. 
Published: May 2014

AbstractA series of directed knockout experiments, combined with an in vitro assay of pathway components, has elucidated for the first time the chemical steps involved in the biosynthesis of the tropolone class of fungal maleic anhydrides. The pathway involves the stepwise oxidation of aldehyde and methyl carbon atoms to form a 1,2‐dicarboxylate. A hydrolase‐catalyzed interconversion of this and the corresponding maleic anhydride, followed by decarboxylation of the diacid leads to the pathway’s final product of stipitatic acid.
Interpnictogen Cations: Exploring New Vistas in Coordination Chemistry
Authors: Robertson Alasdair P. M. , Gray Paul A. , Burford Neil 
Published: May 2014

AbstractPnictine derivatives can behave as both 2e− donors (Lewis bases) and 2e− acceptors (Lewis acids). As prototypical ligands in the coordination chemistry of transition metals, amines and phosphines also form complexes with p‐block Lewis acids, including a variety of pnictogen‐centered acceptors. The inherent Lewis acidity of pnictogen centers can be enhanced by the introduction of a cationic charge, and this feature has been exploited in recent years in the development of compounds resulting from coordinate Pn–Pn and Pn–Pn′ interactions. These compounds offer the unusual opportunity for homoatomic coordinate bonding and the development of complexes that possess a lone pair of electrons at the acceptor center. This Review presents new directions in the systematic extension of coordination chemistry from the transition series into the p‐block.
In Vitro Reconstitution of a Cellular Phase‐Transition Process that Involves the mRNA Decapping Machinery
Authors: Fromm Simon A. , Kamenz Julia , Nöldeke Erik R. , Neu Ancilla , Zocher Georg , Sprangers Remco 
Published: May 2014

AbstractIn eukaryotic cells, components of the 5′ to 3′ mRNA degradation machinery can undergo a rapid phase transition. The resulting cytoplasmic foci are referred to as processing bodies (P‐bodies). The molecular details of the self‐aggregation process are, however, largely undetermined. Herein, we use a bottom‐up approach that combines NMR spectroscopy, isothermal titration calorimetry, X‐ray crystallography, and fluorescence microscopy to probe if mRNA degradation factors can undergo phase transitions in vitro. We show that the Schizosaccharomyces pombe Dcp2 mRNA decapping enzyme, its prime activator Dcp1, and the scaffolding proteins Edc3 and Pdc1 are sufficient to reconstitute a phase‐separation process. Intermolecular interactions between the Edc3 LSm domain and at least 10 helical leucine‐rich motifs in Dcp2 and Pdc1 build the core of the interaction network. We show that blocking of these interactions interferes with the clustering behavior, both in vitro and in vivo.
Improving the cleanability of melamine‐formaldehyde‐based decorative laminates
Authors: Badila Monica , Kohlmayr Martin , Zikulnig‐Rusch Edith Martha , Dolezel‐Horwath Elisabeth , Kandelbauer Andreas 
Published: May 2014

ABSTRACTDecorative laminates based on melamine formaldehyde (MF) resin impregnated papers are used at great extent for surface finishing of engineered wood that is used for furniture, kitchen, and working surfaces, flooring and exterior cladding. In all these applications, optically flawless appearance is a major issue. The work described here is focused on enhancing the cleanability and antifingerprint properties of smooth, matt surface‐finished melamine‐coated particleboards for furniture fronts, without at the same time changing or deteriorating other important surface parameters such as hardness, roughness or gloss. In order to adjust the surface polarity of a low pressure melamine film, novel interface‐active macromolecular compounds were prepared and tested for their suitability as an antifingerprint additive. Two hydroxy‐functional surfactants (polydimethysiloxane, PDMS‐OH and perfluoroether, PF‐OH) were oxidized under mild conditions to the corresponding aldehydes (PDMS‐CHO and PF‐CHO) using a pyridinium chlorochromate catalyst. With the most promising oxidized polymeric additive, PDMS‐CHO, the contact angles against water,n‐hexadecane, and squalene increased from 79.8°, 26.3° and 31.4° for the pure MF surface to 108.5°, 54.8°, and 59.3°, respectively, for the modified MF surfaces. While for the laminated MF surface based on the oxidized fluoroether the gloss values were much higher than required, for the surfaces based on oxidized polydimethylsiloxane the technological values as well as the lower gloss values were in agreement with the requirements and showed much improved surface cleanability, as was also confirmed by colorimetric measurements. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci.2014,131, 40964.
Fish species composition and host fish density in streams of the thick‐shelled river mussel (Unio crassus) – implications for conservation
Authors: Stoeckl Katharina , Taeubert Jens‐Eike , Geist Juergen 
Published: May 2014

Abstract

Recruitment and dispersal of freshwater mussels of the Unionoida is strongly linked to their host fishes on which the larvae develop into juvenile mussels. Host limitation has been suggested as one of the potential causes for the decline of the formerly widespread thick‐shelled river mussel (Unio crassus), although quantitative data analysing the importance of this factor are still missing.
In this study, the status of host fish populations was assessed in nine U. crassus streams within the Danube drainage system situated in southern Germany. In particular, links between recruitment patterns of U. crassus populations, fish species composition and quantitative data of host fish densities in functional and non‐functional streams were established.
Fish species composition and richness ranged between three and nine species with no difference in presence data between functional and non‐functional streams. Despite this high variability, functional U. crassus streams with high proportions of juvenile mussels had significantly higher (mean: 40 Ind. per 100 m2) densities of primary hosts (Phoxinus phoxinus, Squalius cephalus, Gasterosteus aculeatus) than non‐functional streams (mean: 8 Ind. per 100 m2). In contrast, no relationship was found between the numbers and densities of juvenile mussels and densities of poor hosts as well as of non‐hosts.
The results of this study indicate that the recruitment status of U. crassus strongly depends on the density of primary host fish species. Host limitation is likely to play a major role in a lack of juvenile recruitment and consequently in the decline of central European U. crassus populations. Therefore, future conservation for this endangered mussel species should more thoroughly incorporate management of host fish species and consider both the requirements of mussels and their hosts in habitat restoration. Copyright © 2014 John Wiley & Sons, Ltd.
Synthesis of 5‐ and 8‐Deoxytetrodotoxin
Authors: Satake Yoshiki , Adachi Masaatsu , Tokoro Shouta , Yotsu‐Yamashita Mari , Isobe Minoru , Nishikawa Toshio 
Published: May 2014

AbstractTetrodotoxin, a toxic principle of puffer fish intoxication, is one of the most famous marine natural products owing to its complex structure and potent biological activity, which leads to fatal poisoning. Continuous synthetic studies on tetrodotoxin and its analogues to elucidate biologically interesting issues associated with tetrodotoxin have led to the development of versatile routes for a variety of tetrodotoxin derivatives. With the aim of investigating the structure–activity relationship of tetrodotoxin with voltage‐gated sodium channels, this study describes the first total syntheses of 5‐deoxytetrodotoxin, a natural analogue of tetrodotoxin, and 8‐deoxytetrodotoxin, an unnatural analogue, from a newly designed, versatile intermediate in an efficient manner. An estimation of the biological activities of these compounds reveals the importance of the hydroxy groups at the C‐5 and C‐8 positions on the inhibition of voltage‐gated sodium channels.
Synthesis of 1,4,7,10‐Tetra‐azacyclododecan‐1,4,7,10‐tetra‐azidoethylacetic Acid (DOTAZA) and Related “Clickable” DOTA Derivatives
Authors: Kriemen Ella , Ruf Erik , Behrens Ulrich , Maison Wolfgang 
Published: May 2014

AbstractHerein, we report the synthesis of two enantiomeric DOTAZA esters and a related DOT3AZA ester. These compounds are tunable analogues of the well‐known chelator DOTA and can be easily functionalized through click chemistry of the side‐chain azide groups. Like DOTA, DOTAZA forms complexes with various di‐ and trivalent metals, as demonstrated in the synthesis and structural analysis of CuDOTAZA and the preparation of GdDOTAZA.
Enhanced short‐range forecasting of sub‐inversion cloudiness in complex terrain
Authors: Kann Alexander , Schellander‐Gorgas Theresa , Wittmann Christoph 
Published: May 2014

AbstractAccurate spatial and temporal forecasts of fog and low cloud occurrence are still a challenging research topic due to the complexity of its physics. In the nowcasting range, observation‐based techniques are often superior to numerical weather prediction (NWP) models and provide useful guidelines for operational forecasters. This article proposes a low stratus nowcasting scheme which merges station measurements, satellite data, a nowcasting technique and NWP data at a very high horizontal resolution (1 km). Case studies and a comprehensive validation over Austria reveal that the proposed approach of parameterizing sub‐inversion cloudiness adds value especially in complex terrain and even for longer lead times due to the dynamic design of the method.
Optimization of supercritical fluid extraction method for detection of fluquinconazole and tetraconazole in soil using gas chromatography and confirmation using GC‐MS: application to dissipation kinetics
Authors: Park Sang Im , Park Jong‐Hyouk , Ko Ah‐Young , Abd El‐Aty A. M. , Goudah Ayman , Jang Jin , Rahman Md. Musfiqur , Kim Mi Ra , Shim Jae‐Han 
Published: May 2014

ABSTRACTThe aim of this study was to establish an analytical method to detect fluquinconazole and tetraconazole in soil using supercritical fluid extraction (SFE) and gas chromatography (GC). The optimal extraction conditions for SFE were: temperature, 60 °C; pressure, 280 kg/cm2; extraction time, 50 min; and a 10% modifier ratio. The linearity of the calibration curves was good and yielded a determination coefficient (R2) ≥ 0.995. The soil samples were fortified with known quantities of the analytes at three different concentrations (0.01, 0.02 and 0.1 µg/g for fluquinconazole; 0.05, 0.1 and 0.5 µg/g for tetraconazole), and the recoveries ranged between 83.7 and 94.1%. The intra‐ and inter‐day relative standard deviations were 1.3–10.6 and 2.2–11.9% for fluquinconazole and tetraconazole, respectively. The limit of detection and limit of quantitation were 0.002 and 0.01 µg/g for fluquinconazole and 0.01 and 0.05 for tetraconazole, respectively. The method was successfully applied to the analysis of soil residues collected from an onion field. The results show that a combination of SFE and GC can be used as an environmentally friendly technique to detect fungicides in soil. Copyright © 2014 John Wiley & Sons, Ltd.
Comprehensive and temporal analysis of secreted proteins in the medium from IL‐6 exposed human hepatocyte
Authors: Nakata Katsunori , Saitoh Ryoichi , Amano Jun , Ichibangase Tomoko , Ishigai Masaki , Imai Kazuhiro 
Published: May 2014

ABSTRACTWe have previously identified intracellular secretory acute phase response (sAPR) proteins in human hepatocytes following interleukin‐6 (IL‐6) induction by fluorogenic derivatization (FD)–liquid chromatography (LC)–tandem mass spectrometry (MS/MS). In this report, we utilized this method, which uses 7‐chloro‐N‐[2‐(dimethylamino)ethyl]‐2,1,3‐benzoxadiazole‐4‐sulfonamide (DAABD‐Cl) as the FD reagent, to comprehensively and time‐dependently analyze secreted proteins in the medium, including sAPR proteins. Since DAABD‐Cl selectively reacts with thiol moieties of cysteinyl residues, direct derivatization, high‐resolution LC separation and identification of the secreted proteins in the culture medium were successfully achieved without a pretreatment step. As a result, 14 sAPR proteins were identified simultaneously during a 72 h induction by IL‐6. The secretion levels of 11 proteins increased, whereas the secretion levels of three important transport proteins decreased (albumin, retinol‐binding protein 4 and transthyretin). In addition, the secretion level of a haptoglobin was found to increase significantly between 0 and 6 h by 1.88‐fold compared with the control sample. The secretion levels of four cytoplasmic proteins increased: LDH, a known marker for cell damage, and GSTA1, FABP1 and ADH1B, which are marker proteins for hepatocellular damage. The secretion levels of the other two newly identified cytoplasmic proteins, profilin‐1 and SOD2, were also found to increase, suggesting that these two proteins represent novel markers for cell damage. These results suggest that the FD‐LC‐MS/MS proteomics method can be used to analyze comprehensively and time‐dependently the secreted proteins and thereby can offer information that aids our understanding of the dynamics of protein secretion affected by the exposure of cytokines such as IL‐6. Copyright © 2013 John Wiley & Sons, Ltd.
Analysis of etoxazole in red pepper after major modification of QuEChERS for gas chromatography–nitrogen phosphorus detection
Authors: Jang Jin , Rahman Md. Musfiqur , Abd El‐Aty A. M. , Ko Ah‐Young , Park Jong‐Hyouk , Choi Jeong‐Heui , Park Ki. Hun , Yang Angel , Seo Young Mi , Shim Jae‐Han 
Published: May 2014

ABSTRACTA major modification to the QuEChERS (quick, easy, cheap, effective, rugged and safe) method was developed for the analysis of etoxazole in red pepper using gas chromatography coupled with a nitrogen–phosphorus detector. Etoxazole was extracted with acetonitrile, partitioned with magnesium sulfate and purified with a solid‐phase extraction cartridge. The method showed good linearity with a determination coefficient (R2) of 0.998 for the 0.02–2.0 mg/L concentration range. The method was validated using blank red pepper spiked at 0.2 and 1.0 mg/kg, and the average recovery rate was 74.4–79.1% with relative standard deviations <5% for intra‐ and inter‐day precision. The limits of detection and quantification were 0.007 and 0.02 mg/kg, respectively. The developed method was successfully applied to field‐incurred samples, and the presence of etoxazole residues was confirmed using gas chromatography/mass spectrometry. Copyright © 2014 John Wiley & Sons, Ltd.
Quantitation of P450 3A4 endogenous biomarker – 4β‐hydroxycholesterol – in human plasma using LC/ESI‐MS/MS
Authors: Huang Mike‐Qingtao , Lin Weisheng , Wang Weimin , Zhang Wei , Lin Zhongping (John) , Weng Naidong 
Published: May 2014

ABSTRACT4β‐Hydroxycholesterol (4β‐HC) has been proposed as a new endogenous biomarker for cytochrome P450 3A4/5 activity. Therefore, it is important to have a robust method for its accurate determination in human plasma. Here a liquid chromatography–tandem mass spectrometry with electrospray ionization (LC/ESI‐MS/MS) assay for the quantitation of 4β‐HC in human plasma is described. While the calibration standards were prepared in a surrogate matrix for human plasma, the quality control samples were prepared in human plasma to mimic the incurred study samples. In order to achieve accurate determination of 4β‐HC, the chromatographic separation of 4β‐HC from its isomers, especially 4α‐hydroxycholesterol (4α‐HC), was crucial. In the absence of an authentic 4α‐HC standard at the time of this study, an alternative selectivity test strategy was developed to confirm the separation. After being alkalized with potassium hydroxide, the human plasma sample (50 μL) was extracted with hexane, derivatized into picolinyl esters using picolinic acid, extracted again with hexane, and then analyzed by LC/ESI‐MS/MS. The calibration curve range was 5–500 ng/mL and the chromatographic separation was achieved on a 50 × 2.1 mm Thermal Hypersil Gold column with a gradient elution. The assay accuracy, precision, linearity, selectivity and analyte stability throughout the analysis were established. The validated assay was successfully applied to a Phase I clinical study for the measurement of 4β‐HC in human plasma. Copyright © 2014 John Wiley & Sons, Ltd.
Development and validation of UHPLC method for the determination of cyclosporine A in biological samples
Authors: Szerkus Oliwia , Wolska Eliza , Struck‐Lewicka Wiktoria , Siluk Danuta , Radwańska Aleksandra , Wiczling Paweł , Chorążewicz Juliusz , Sznitowska Małgorzata , Markuszewski Michał J. , Kaliszan Roman 
Published: May 2014

ABSTRACTThe aim of the study was to develop and validate a simple and rapid method for the determination of cyclosporine A (CsA) in ocular rabbit tissues using reversed‐phase ultra‐high‐performance liquid chromatography (UHPLC) with UV detection. Previous publications on chromatographic methods of CsA determination in ocular tissues involved only reversed‐phase HPLC separation, usually in combination with such detection techniques as radio‐immunoassay and mass spectrometry. The application of the UHPLC technique allowed us to significantly decrease the analysis time. Cyclosporine D (CsD) was applied as the internal standard. Satisfactory separation was achieved on an XB‐C18 Kinetex column at 60°C with the use of gradient elution mode. The retention times of CsA and CsD were found to be 4.5 and 5.1 min, respectively. The developed assay is specific, sensitive (limit of detection = 6 ng/mL and limit of quantitation = 18 ng/mL) and linear within the analyte concentration range of 0.018–5 µg/mL, with a correlation coefficient of 0.999. High sensitivity, low injection volume (10 μL), short time of analysis (6.5 min) and simplicity make this method useful for the fast analysis of CsA in rabbit ocular tissues and fluids: lacrimal fluid, aqueous humor, cornea, conjunctiva and eye globe. Copyright © 2014 John Wiley & Sons, Ltd.
Liquid chromatographic enantioseparation of (RS)‐mexiletine and (RS)‐fluoxetine using chiral derivatizing reagents synthesized with (S)‐naproxen moiety
Authors: Batra Sonika , Bhushan Ravi 
Published: May 2014

ABSTRACTEnantiomeric separation of racemic mexiletine and fluoxetine was achieved using three chiral derivatizing reagents (CDRs) based on (S)‐naproxen. Diastereomers were synthesized by reaction of mexiletine or fluoxetine with the CDRs and were separated on a C18 column under reversed‐phase conditions using a binary mixture of acetonitrile and triethylammonium phosphate/water, with UV detection at 230 and 226 nm. The results obtained for enantioseparation of the two drugs using the three CDRs were compiled and compared. The conditions for derivatization and chromatographic separation were optimized. The method was validated for linearity, repeatability, limit of detection and limit of quantification. Copyright © 2014 John Wiley & Sons, Ltd.
Microextraction by packed sorbent: an emerging, selective and high‐throughput extraction technique in bioanalysis
Authors: Pereira Jorge , Câmara José S. , Colmsjö Anders , Abdel‐Rehim Mohamed 
Published: May 2014

ABSTRACTSample preparation is an important analytical step regarding the isolation and concentration of desired components from complex matrices and greatly influences their reliable and accurate analysis and data quality. It is the most labor‐intensive and error‐prone process in analytical methodology and, therefore, may influence the analytical performance of the target analytes quantification. Many conventional sample preparation methods are relatively complicated, involving time‐consuming procedures and requiring large volumes of organic solvents. Recent trends in sample preparation include miniaturization, automation, high‐throughput performance, on‐line coupling with analytical instruments and low‐cost operation through extremely low volume or no solvent consumption. Micro‐extraction techniques, such as micro‐extraction by packed sorbent (MEPS), have these advantages over the traditional techniques. This paper gives an overview of MEPS technique, including the role of sample preparation in bioanalysis, the MEPS description namely MEPS formats (on‐ and off‐line), sorbents, experimental and protocols, factors that affect the MEPS performance, and the major advantages and limitations of MEPS compared with other sample preparation techniques. We also summarize MEPS recent applications in bioanalysis. Copyright © 2014 John Wiley & Sons, Ltd.