bluuebunny/crossref_metadata_2025 huggingface dataset:
Ejigabwîn
Authors: Saint-Arnaud Marie , Papatie Charlie
Published: April 2014

La forêt est au coeur du paysage culturel des Anichinabés de Kitcisakik. Comme c’est le cas pour de nombreuses nations autochtones du Canada, le territoire ancestral de cette communauté algonquine du Québec a fait l’objet d’interventions forestières continues depuis la fin du xixe siècle. Pour faire face à cette problématique, les gens de Kitcisakik ont choisi de s’engager dans un processus de recherche collaborative, appuyé par un cadre de référence en éducation relative à l’environnement. Cette initiative a permis d’amorcer un dialogue interculturel dans le but de définir les fondements d’une foresterie mieux adaptée au contexte autochtone. L’enquête menée par les auteurs a mis au jour le caractère identitaire de la forêt (nopimik) pour les Anichinabés et la dimension préoccupante de la foresterie. À partir du système anichinabé de représentation, ils ont élaboré un cadre de cinq principes (culturel, éthique, éducatif, écologique et économique) et de vingtdeux critères de foresterie autochtone. Cette proposition est analysée dans le contexte des changements normatifs et législatifs apportés au Québec par la nouvelle Loi sur l’aménagement durable du territoire forestier et le resserrement des critères de certification forestière du Forest Stewardship Council (FSC).
FRET-based reporters for the direct visualization of abscisic acid concentration changes and distribution in Arabidopsis
Authors: Waadt Rainer , Hitomi Kenichi , Nishimura Noriyuki , Hitomi Chiharu , Adams Stephen R , Getzoff Elizabeth D , Schroeder Julian I
Published: April 2014

Abscisic acid (ABA) is a plant hormone that regulates plant growth and development and mediates abiotic stress responses. Direct cellular monitoring of dynamic ABA concentration changes in response to environmental cues is essential for understanding ABA action. We have developed ABAleons: ABA-specific optogenetic reporters that instantaneously convert the phytohormone-triggered interaction of ABA receptors with PP2C-type phosphatases to send a fluorescence resonance energy transfer (FRET) signal in response to ABA. We report the design, engineering and use of ABAleons with ABA affinities in the range of 100–600 nM to map ABA concentration changes in plant tissues with spatial and temporal resolution. High ABAleon expression can partially repress Arabidopsis ABA responses. ABAleons report ABA concentration differences in distinct cell types, ABA concentration increases in response to low humidity and NaCl in guard cells and to NaCl and osmotic stress in roots and ABA transport from the hypocotyl to the shoot and root.
The budding yeast Centromere DNA Element II wraps a stable Cse4 hemisome in either orientation in vivo
Authors: Henikoff Steven , Ramachandran Srinivas , Krassovsky Kristina , Bryson Terri D , Codomo Christine A , Brogaard Kristin , Widom Jonathan , Wang Ji-Ping , Henikoff Jorja G
Published: April 2014

In budding yeast, a single cenH3 (Cse4) nucleosome occupies the ∼120-bp functional centromere, however conflicting structural models for the particle have been proposed. To resolve this controversy, we have applied H4S47C-anchored cleavage mapping, which reveals the precise position of histone H4 in every nucleosome in the genome. We find that cleavage patterns at centromeres are unique within the genome and are incompatible with symmetrical structures, including octameric nucleosomes and (Cse4/H4)2 tetrasomes. Centromere cleavage patterns are compatible with a precisely positioned core structure, one in which each of the 16 yeast centromeres is occupied by oppositely oriented Cse4/H4/H2A/H2B hemisomes in two rotational phases within the population. Centromere-specific hemisomes are also inferred from distances observed between closely-spaced H4 cleavages, as predicted from structural modeling. Our results indicate that the orientation and rotational position of the stable hemisome at each yeast centromere is not specified by the functional centromere sequence.
Pullulan: Properties, Synthesis, and Applications
Authors: LeDuy Anh , Choplin Lionel , Zajic James E. , Luong John H. T.
Published: April 2014

Pullulan is a water‐soluble extracellular polysaccharide, which consists of linear chains ofd‐glucopyranosyl units that alternate regularly between one (1→6)‐α‐dand two (1→4)‐α‐dlinkages, or alternatively a linear polymer of maltotriosyl units connected by (1→6)‐α‐dlinkages. Bauer in 1938 was the first to observe the polysaccharide produced by theAureobasidium pullulansfungus. This article reviews the physical, chemical, and biochemical properties of pullulan. Practical aspects such as laboratory‐ and industrial‐scale production as well as food, industry, and medical applications of pullulans and their derivatives are also discussed.
Percolation of CO2‐rich fluids in a limestone sample: Evolution of hydraulic, electrical, chemical, and structural properties
Authors: Vialle Stéphanie , Contraires Simon , Zinzsner Bernard , Clavaud Jean‐Baptiste , Mahiouz Karim , Zuddas Pierpaolo , Zamora Maria
Published: April 2014

Percolation of CO2‐rich fluids in limestones causes the dissolution (and eventual reprecipitation) of calcium carbonate minerals, which affect the rock microstructure and change the rock petrophysical properties (i.e., hydraulic, electrical, and elastic properties). In addition, microstructural changes further feed back to affect the chemical reactions. To better understand this coupled problem and to assess the possibility of geophysical monitoring, we performed reactive percolation laboratory experiments on a well‐characterized carbonate sample 35 cm in length and 10 cm in diameter. In a comprehensive study, we present integrated measurements of aqueous chemistry (pH, calcium concentration, and total alkalinity), petrophysical properties (permeability, electrical formation factor, and acoustic velocities), and X‐ray tomography imaging. The measured chemical and electrical parameters allowed rapid detection of the dissolution of calcite in the downstream fluid. After circulating fluids of various salinities at 5mL min−1 for 32 days (about 290 pore sample volumes) at a pCO2 of 1 atm (pH = 4), porosity increased by 7% (from 0.29 to 0.31), permeability increased by 1 order of magnitude (from 0.12 D to 0.97 D), and the electrical formation factor decreased by 15% (from 15.7 to 13.3). X‐ray microtomography revealed the creation of wormholes; these, along with the convex curvature of the permeability‐porosity relationship, are consistent with a transport‐controlled dissolution regime for which advection processes are greater than diffusion processes, confirming results from previous numerical studies. This study shows that nonseismic geophysical techniques (i.e., electrical measurements) are promising for monitoring geochemical changes within the subsurface due to fluid‐rock interactions.
Solar forcing of Nile discharge and sapropel S1 formation in the early to middle Holocene eastern Mediterranean
Authors: Hennekam Rick , Jilbert Tom , Schnetger Bernhard , de Lange Gert J.
Published: April 2014

We present high‐resolution records for oxygen isotopes of the planktic foraminifer Globigerinoides ruber (δ18Oruber) and bulk sediment inorganic geochemistry for Holocene‐age sediments from the southeast Mediterranean. Our δ18Oruber record appears to be dominated by Nile discharge rather than basin‐scale salinity/temperature changes. Nile discharge was enhanced in the early to middle Holocene relative to today. The timing of the long‐term maximum in Nile discharge during the early Holocene corresponds to the timing of maximum intensity of the Indian Ocean‐influenced Southwest Indian summer monsoon (SIM). This coincidence suggests a major influence of an Indian Ocean moisture source on Nile discharge in the early to middle Holocene, while, presently, the Atlantic Ocean is the main moisture source. Nile discharge was highly variable on multicentennial time scale during the early to middle Holocene, being strongly influenced by variable solar activity. This solar‐driven variability is also recorded in contemporaneous SIM records, however, not observed in an Atlantic Ocean‐derived West African summer monsoon record from the Holocene. This supports the hypothesis that the Indian Ocean moisture source predominantly controlled Nile discharge at that time. Solar‐driven variability in Nile discharge also influenced paleoenvironmental conditions in the eastern Mediterranean. Bulk sediment Ba/Al and V/Al, used as indicators for (export) productivity and redox conditions, respectively, varied both in response to solar forcing on multicentennial time scales. We suggest that changes in Nile discharge on these time scales have been concordant with nutrient inputs to, and shallow ventilation of, the eastern Mediterranean.
Effect of soil properties on peat erosion and suspended sediment delivery in drained peatlands
Authors: Tuukkanen Tapio , Marttila Hannu , Kløve Bjørn
Published: April 2014

Erosion from peat extraction areas is known to cause siltation of water courses and poor water quality. However, the main soil parameters affecting peat erosion and suspended sediment (SS) yields from different catchments are not well understood. This paper used peat properties (degree of humification, peat type, ash content, porosity, moisture content, bulk density, and shear strength) and novel erosion threshold measurements from intact soil cores to explain peat erodibility and spatial variations in SS concentrations (SSCs) and SS loads (SSLs) at 20 Finnish peat extraction sites. The erosion threshold measurements suggested that critical shear stresses for particle entrainment decrease with increasing degree of humification (von Post scale) and are significantly lower in well‐decomposed peat than in slightly or moderately decomposed peat. Two critical shear stresses were obtained from moderately decomposed peat samples, indicating a degree of surface armoring by coarse peat fibers. Monitored long‐term average SSC was highest at study sites with well‐decomposed peat, while very fine‐grained mineral subsoil explained some of the highest long‐term SSC in areas where drainage ditches penetrated below the upper peat layer. Average SSL (kg d−1) at the study sites was best explained (R2 = 0.89) by average discharge and surface peat decomposition level. Overall, this study provides new knowledge on peat erosion and critical shear stresses that can be used in water conservation and sediment management practices for cutover peatlands and other similar land uses.
NSF Geosciences Committee Focuses on Program and Budget Issues
Authors: Showstack Randy
Published: April 2014

The spring meeting of the National Science Foundation's (NSF) Advisory Committee for the Geosciences (AC GEO), held on 3–4 April, was filled with firsts. It was the first time that AC GEO met as a body after merging with NSF's polar advisory committee in 2012. In addition, it was the first time that France Córdova, sworn in as the new NSF director on 31 March and sworn in again during a special ceremony in the atrium at NSF headquarters on 3 April, met with AC GEO in her new capacity. Córdova, who is president emerita of Purdue University, previously was a distinguished professor of physics and astronomy at the University of California, Riverside, and NASA chief scientist.
Scientists Identify Exploration Goals for Venus
Authors: Kumar Mohi
Published: April 2014

Since the turn of the millennium, a large proportion of NASA's planetary science missions—including spacecraft and payloads on four orbiting missions and three rovers—has targeted Mars in preparation for future human missions to the red planet. Less studied, however, is Venus.
Studying Statistical Methodology in Climate Research
Authors: Thorarinsdottir Thordis , Sillmann Jana , Benestad Rasmus
Published: April 2014

Climate can be viewed as having two facets: the statistics of weather and the physics describing the underlying processes. Hence, climate science inherently relies heavily on statistical methodology.
UV Direct Write Metal Enhanced Redox (MER) Domain Engineering for Realization of Surface Acoustic Devices on Lithium Niobate
Authors: Yudistira Didit , Boes Andreas , Rezk Amgad R. , Yeo Leslie Y. , Friend James R. , Mitchell Arnan
Published: April 2014

A new and highly versatile domain patterning method—ultraviolet direct write metal enhanced redox (UV direct write MER)—achieves deep domains with practically no thermally‐induced damage on the surface of lithium niobate crystals. In UV direct write MER, after coating with a thin layer of chromium, the domain inversion is generated by a redox process induced in the crystal by illumination with high intensity UV in an ambient dry nitrogen atmosphere. This new technique enables the fabrication of practical piezoelectric acoustic superlattice structures on 128° YX‐cut LiNbO3, the most widely used crystal cut for surface acoustic wave applications. For example, UV direct write MER was used to form an acoustic superlattice 128° YX structure that in turn enabled the generation of surface acoustic waves of sufficient strength to develop fluid flow within a droplet of water, demonstrating its potential in practical microfluidic manipulation. This is the first demonstration of a UV direct write surface acoustic wave transducer reported to date, made possible only due to the unique qualities of the MER domain engineering process.
Chemoselective Synthesis of Unsymmetrical Internal Alkynes or Vinyl Sulfones via Palladium‐Catalyzed Cross‐Coupling Reaction of Sodium Sulfinates with Alkynes
Authors: Xu Yanli , Zhao Jinwu , Tang Xiaodong , Wu Wanqing , Jiang Huanfeng
Published: April 2014

A highly efficient and mild palladium‐catalyzed cross‐coupling of sodium sulfinates and alkynes for the selective synthesis of unsymmetrical internal alkynes and vinyl sulfones has been developed. This methodology has advantages of easily accessible starting materials, functional group tolerance and a wide range of substrates, which provides rapid access to alkynes and vinyl sulfones.

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Chemoselective Additions of Chloromethyllithium Carbenoid to Cyclic Enones: A Direct Access to Chloromethyl Allylic Alcohols
Authors: Pace Vittorio , Castoldi Laura , Holzer Wolfgang
Published: April 2014

Chloromethyllithium carbenoid has been chemoselectively added to cyclic enones (5‐, 6‐ and 7‐membered systems, including two natural products) to provide chloromethyl allylic alcohols. Under the optimized reaction conditions neither concomitant (n+1) homologation nor conjugate addition or Simmons–Smith‐like cyclopropanation takes place. The presence of LiBr is estimated to play a dual role, namely as a carbenoid stabilizer and mild Lewis acid activator of the CO group. Notably, the mesomeric effect caused by β‐heteroatom‐containing substituents promotes the attack of the reagent at the most activated position.

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Titanium‐Catalyzed, One‐Pot Synthesis of 2‐Amino‐3‐cyano‐ pyridines
Authors: Dissanayake Amila A. , Staples Richard J. , Odom Aaron L.
Published: April 2014

Earth‐abundant and inexpensive titanium can catalyze alkyne iminoamination, which generates tautomers of 1,3‐diimines. Upon treatment with base (DBU) and malononitrile, the multicomponent coupling product is converted to 2‐amino‐3‐cyanopyridines in a one‐pot procedure in good to modest yields. There is substantial control of regioselectivity for the substituents on the pyridine ring and on the 2‐amino group. Several studies were done that provide significant evidence for a Dimroth rearrangement mechanism for 2‐aminopyridine formation, including isolation of a 2‐imino‐1,2‐dihydropyridine intermediate that undergoes rearrangement under the reaction conditions.

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Ruthenium‐ and Rhodium‐Catalyzed Dehydrogenative ortho‐Alkenylation of Benzylamines via Free Amino Group Directed CH Bond Cleavage
Authors: Suzuki Chiharu , Morimoto Keisuke , Hirano Koji , Satoh Tetsuya , Miura Masahiro
Published: April 2014

The dehydrogenative direct coupling of α,α‐disubstituted benzylamines with acrylates takes place efficiently at room temperature under ruthenium catalysis, accompanied by free amino group‐directed ortho‐alkenylation and successive cyclization to produce (isoindol‐1‐yl)acetic acid derivatives. The reactions using styrenes in place of acrylates proceed effectively in the presence of a rhodium catalyst rather than ruthenium.

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Flexible and Highly Scalable V2O5‐rGO Electrodes in an Organic Electrolyte for Supercapacitor Devices
Authors: Foo Ce Yao , Sumboja Afriyanti , Tan Daniel Jia Hong , Wang Jiangxin , Lee Pooi See
Published: April 2014

Vanadium pentoxide–reduced graphene oxide (rGO) free‐standing electrodes are used as electrodes for supercapacitor applications, eliminating the need for current collectors or additives and reducing resistance (sheet resistance 29.1 Ω □−1). The effective exfoliation of rGO allows improved electrolyte ions interaction, achieving high areal capacitance (511.7 mF cm−2) coupled with high mass loadings. A fabricated asymmetric flexible device based on rGO/V2O5‐rGO (VGO) consists of approximately 20 mg of active mass and still delivers a low equivalent series resistance (ESR) of 3.36 Ω with excellent cycling stability. A prototype unit of the assembled device with organic electrolyte is shown to light up eight commercial light‐emitting diode bulbs.
Evidence for increased SOX3 dosage as a risk factor for X‐linked hypopituitarism and neural tube defects
Authors: Bauters Marijke , Frints Suzanna G. , Van Esch Hilde , Spruijt Liesbeth , Baldewijns Marcella M. , Die‐Smulders Christine E. M. de , Fryns Jean‐Pierre , Marynen Peter , Froyen Guy
Published: April 2014

Genomic duplications of varying lengths at Xq26–q27 involving SOX3 have been described in families with X‐linked hypopituitarism. Using array‐CGH we detected a 1.1 Mb microduplication at Xq27 in a large family with three males suffering from X‐linked hypopituitarism. The duplication was mapped from 138.7 to 139.8 Mb, harboring only two annotated genes, SOX3 and ATP11C, and was shown to be a direct tandem copy number gain. Unexpectedly, the microduplication did not fully segregate with the disease in this family suggesting that SOX3 duplications have variable penetrance for X‐linked hypopituitarism. In the same family, a female fetus presenting with a neural tube defect was also shown to carry the SOX3 copy number gain. Since we also demonstrated increased SOX3 mRNA levels in amnion cells derived from an unrelated t(X;22)(q27;q11) female fetus with spina bifida, we propose that increased levels of SOX3 could be a risk factor for neural tube defects. © 2014 Wiley Periodicals, Inc.
Informing conservation management about structural versus functional connectivity: A case‐study of Cross River gorillas
Authors: Imong Inaoyom , Robbins Martha M. , Mundry Roger , Bergl Richard , Kühl Hjalmar S.
Published: April 2014

Connectivity among subpopulations is vital for the persistence of small and fragmented populations. For management interventions to be effective conservation planners have to make the critical distinction between structural connectivity (based on landscape structure) and functional connectivity (which considers both landscape structure and organism‐specific behavioral attributes) which can differ considerably within a given context. We assessed spatial and temporal changes in structural and functional connectivity of the Cross River gorilla Gorilla gorilla diehli (CRG) population in a 12,000 km2 landscape in the Nigeria‐Cameroon border region over a 23‐year period, comparing two periods: 1987–2000 and 2000–2010. Despite substantial forest connections between occupied areas, genetic evidence shows that only limited dispersal occurs among CRG subpopulations. We used remotely sensed land‐cover data and simulated human pressure (using a spatially explicit agent‐based model) to assess human impact on connectivity of the CRG population. We calculated cost‐weighted distances between areas occupied by gorillas as measures of connectivity (structural based on land‐cover only, functional based on both land‐cover and simulated human pressure). Whereas structural connectivity decreased by 5% over the 23‐year period, functional connectivity decreased by 11%, with both decreasing more during the latter compared to the earlier period. Our results highlight the increasing threat of isolation of CRG subpopulations due to human disturbance, and provide insight into how increasing human influence may lead to functional isolation of wildlife populations despite habitat continuity, a pressing and common issue in tropical Africa often not accounted for when deciding management interventions. In addition to quantifying threats to connectivity, our study provides crucial evidence for management authorities to identify actions that are more likely to be effective for conservation of species in human‐dominated landscapes. Our approach can be easily applied to other species, regions, and scales. Am. J. Primatol. 76:978–988, 2014. © 2014 Wiley Periodicals, Inc.
A Novel Type of Luciferin from the Siberian Luminous Earthworm Fridericia heliota: Structure Elucidation by Spectral Studies and Total Synthesis
Authors: Petushkov Valentin N. , Dubinnyi Maxim A. , Tsarkova Aleksandra S. , Rodionova Natalja S. , Baranov Mikhail S. , Kublitski Vadim S. , Shimomura Osamu , Yampolsky Ilia V.
Published: April 2014

The structure elucidation and synthesis of the luciferin from the recently discovered luminous earthworm Fridericia heliota is reported. This luciferin is a key component of a novel ATP‐dependent bioluminescence system. UV, fluorescence, NMR, and HRMS spectroscopy studies were performed on 0.005 mg of the isolated substance and revealed four isomeric structures that conform to spectral data. These isomers were chemically synthesized and one of them was found to produce light when reacted with a protein extract from F. heliota. The novel luciferin was found to have an unusual extensively modified peptidic nature, thus implying an unprecedented mechanism of action.
Fluorescent Mimetics of CMP‐Neu5Ac Are Highly Potent, Cell‐Permeable Polarization Probes of Eukaryotic and Bacterial Sialyltransferases and Inhibit Cellular Sialylation
Authors: Preidl Johannes J. , Gnanapragassam Vinayaga S. , Lisurek Michael , Saupe Jörn , Horstkorte Rüdiger , Rademann Jörg
Published: April 2014

Oligosaccharides of the glycolipids and glycoproteins at the outer membranes of human cells carry terminal neuraminic acids, which are responsible for recognition events and adhesion of cells, bacteria, and virus particles. The synthesis of neuraminic acid containing glycosides is accomplished by intracellular sialyl transferases. Therefore, the chemical manipulation of cellular sialylation could be very important to interfere with cancer development, inflammations, and infections. The development and applications of the first nanomolar fluorescent inhibitors of sialyl transferases are described herein. The obtained carbohydrate‐nucleotide mimetics were found to bind all four commercially available and tested eukaryotic and bacterial sialyl transferases in a fluorescence polarization assay. Moreover, it was observed that the anionic mimetics intruded rapidly and efficiently into cells in vesicles and translocated to cellular organelles surrounding the nucleus of CHO cells. The new compounds inhibit cellular sialylation in two cell lines and open new perspectives for investigations of cellular sialylation.
A Base‐Free Neutral Phase‐Transfer Reaction System
Authors: Shirakawa Seiji , Wang Lijia , He Rongjun , Arimitsu Satoru , Maruoka Keiji
Published: April 2014

Although phase‐transfer reactions catalyzed by using quaternary ammonium salts are generally believed to require base additives, we discovered that, even without any base additives, conjugate additions of 3‐substituted oxindoles to nitroolefins proceeded smoothly in the presence of lipophilic quaternary ammonium bromide under water–organic biphasic conditions. The mechanism of this novel base‐free neutral phase‐transfer reaction system is investigated and the assumed catalytic cycle is presented together with interesting effects of water and lipophilicity of the phase‐transfer catalyst. The base‐free neutral phase‐transfer reaction system can be applied to highly enantioselective conjugate addition and aldol reactions under the influence of chiral bifunctional ammonium bromides as key catalysts. The structure of the chiral ammonium enolate intermediate is discussed based on the single‐crystal X‐ray structures of relevant ammonium salts and the importance of bifunctional design of catalyst is clearly explained in the model of intermediate.
Paläoklimaforschung auf dem Dach der Welt
Authors: Frenzel Peter , Günther Franziska , Kasper Thomas , Henkel Karoline
Published: April 2014

Basierend auf mehreren Expeditionen geben wir einen kurzen Überblick über Methoden zur Rekonstruktion des Paläoklimas im Hochland von Tibet. Schwierige Arbeitsbedingungen in eingeschränkt zugänglichen und wenig erschlossenen Gebieten auf Höhen um 4500 m über dem Meeresspiegel sind für diese Expeditionen charakteristisch. Neben sedimentologischen und geochemischen Analysen sind es vor allem Mikrofossilien und Biomarker, die als Archive von Umweltveränderungen der jüngeren geologischen Vergangenheit genutzt werden, da sie gut verfügbar und vielseitig interpretierbar sind. Veränderungen des Seespiegels, der Wasserchemie, von biologischer Produktivität, Temperatur, Vegetation und anderen Parametern sind mit diesen Methoden rekonstruierbar. Ihre prozessorientierte Interpretation ermöglicht es, räumliche und zeitliche Verschiebungen des Monsunsystems zu identifizieren.
MOOCs – Lernen im Internet
Authors: Buldun Can , Illenberger Susanne , Springer Sebastian
Published: April 2014

Massive open online courses (oder “MOOCs”) sind kostenlose, internetbasierte Kurse, in denen Sachverhalte anschaulich und kurzweilig dargestellt werden. Die Zahl der angebotenen Kurse steigt rasant und das Spektrum an Themengebieten ist nahezu unbegrenzt.

??Unser englischsprachiger MOOC “DNA – from structure to therapy” wendet sich an Schüler von Gymnasien und High Schools auf der ganzen Welt, die an Biologie interessiert sind und womöglich eine Karriere in den Lebenswissenschaften planen. Obwohl das Konzept von MOOCs derzeit noch nicht vollständig ausgereift ist, haben MOOCs aufgrund ihrer zahlreichen Vorteile ein hohes Potenzial, ein fester Bestandteil der weltweiten Bildungslandschaft zu werden.
Dicke Brummer: Schein‐Hummeln und das Insekt des Jahres
Authors: Petrischak Hannes
Published: April 2014

Fliegen haben in weiten Teilen der Bevölkerung nicht gerade den besten Ruf, gelten sie doch bei wenig differenzierter Betrachtung als lästig oder sogar eklig. Doch sie wecken durch Mimikry, als nützliche Räuber, spezialisierte Parasitoide oder begehrte Beutetiere anderer Insekten schnell das Interesse des aufmerksamen Natur‐Beobachters. Eine Wanzenfliege hat es nun sogar zum “Insekt des Jahres” geschafft.
Determination of pinocembrin in human plasma by solid‐phase extraction and LC/MS/MS: application to pharmacokinetic studies
Authors: Yan Bei , Cao Guoying , Sun Taohua , Zhao Xi , Hu Xin , Yan Jiling , Peng Yueying , Shi Aixin , Li Yang , Xue Wei , Li Min , Li Kexin , Liu Yingfa
Published: April 2014

A sensitive, fast and specific method for the quantitation of pinocembrin in human plasma based on high‐performance liquid chromatography–tandem mass spectrometry (LC/MS/MS) was developed and validated. Clonazepam was used as the internal standard (IS). After solid‐phase extraction of 500 μL plasma, pinocembrin and the IS were separated on a Luna C8 column using the mobile phase composed of acetonitrile–0.3 mm ammonium acetate solution (65:35, v/v) at a flow rate of 0.25 mL/min in isocratic mode. The detection was performed on a triple quadrupole tandem mass spectrometer by multiple reaction monitoring via an electrospray ionization source in negative mode by AB SCIEX Qtrap 5500. The assay was linear from 1 to 400 ng/mL, with within‐ and between‐run accuracy (relative error) from −1.82 to 0.54%, and within‐ and between‐run precision (CV) below 5.25%. The recovery was above 88% for the analyte at 1, 50 and 300 ng/mL. This analytical method was successful for the determination of pinocembrin in human plasma and applied to a pharmacokinetic study of pinocembrin injection in healthy volunteers after intravenous drip administration. Copyright © 2014 John Wiley & Sons, Ltd.
Analysis of parabens in dentifrices and the oral cavity
Authors: Park Yong‐Duk , Jang Jong‐Hwa , Park Jung‐Eun , Kim Ji Hyun , Kim Eun‐Cheol , Song Yun‐Jung , Kwon Ha‐Jeong
Published: April 2014

This study analyzed levels of parabens in commercial dentifrices and saliva. HPLC was performed using 35% acetonitrile and measuring absorbance at 254 nm. Thirteen toothpastes and five mouthwashes were analyzed. Of these, volunteers used three toothpastes and two mouthwashes, and levels of parabens were analyzed in saliva and water used for mouth rinsing. In toothpastes, the highest concentrations of methylparaben (MP), propylparaben (PP) and n‐butylparaben (nBP) were 1.86, 1.42 and 1.87 mg/g, respectively. In mouthwashes, the highest concentrations of MP and PP were 0.97 and 0.11 mg/mL, respectively. After volunteers used 500 mg toothpaste T‐1, which contained 895 µg MP, the first and tenth mouth rinse samples contained means of 64.63 and 1.89 µg MP, respectively. After rinsing the mouth three or five times, 37 µg or 18 µg MP was calculated to remain in the oral cavity, respectively. After using 20 mL mouthwash S‐1, which contained 19 mg MP, 1.53 mg MP was calculated to remain in the oral cavity. Immediately after using this mouthwash, the mean salivary concentration of MP was 237 µg/mL. The daily intake of parabens from dentifrices was predicted to be insignificant compared with the intake from food; however, parabens can be ingested from dentifrices. Copyright © 2014 John Wiley & Sons, Ltd.
Structural Basis of Furan–Amino Acid Recognition by a Polyspecific Aminoacyl‐tRNA‐Synthetase and its Genetic Encoding in Human Cells
Authors: Schmidt Moritz J. , Weber Annemarie , Pott Moritz , Welte Wolfram , Summerer Daniel
Published: April 2014

The site‐selective introduction of photo‐crosslinking groups into proteins enables the discovery and mapping of weak and/or transient protein interactions with high spatiotemporal resolution, both in vitro and in vivo. We report the genetic encoding of a furan‐based, photo‐crosslinking amino acid in human cells; it can be activated with red light, thus offering high penetration depths in biological samples. This is achieved by activation of the amino acid and charging to its cognate tRNA by a pyrrolysyl‐tRNA‐synthetase (PylRS) mutant with broad polyspecificity. To gain insights into the recognition of this amino acid and to provide a rationale for its polyspecificity, we solved three crystal structures of the PylRS mutant: in its apo‐form, in complex with adenosine 5′‐(β,γ‐imido)triphosphate (AMP‐PNP) and in complex with the AMP ester of the furan amino acid. These structures provide clues for the observed polyspecificity and represent a promising starting point for the engineering of PylRS mutants with further increased substrate scope.
Synthesis and Peroxidase‐Like Activity of Salt‐Resistant Platinum Nanoparticles by Using Bovine Serum Albumin as the Scaffold
Authors: He Shao‐Bin , Deng Hao‐Hua , Liu Ai‐Lin , Li Guang‐Wen , Lin Xin‐Hua , Chen Wei , Xia Xing‐Hua
Published: April 2014

A green approach is proposed for the synthesis of Pt nanoparticles (PtNPs) in the bovine serum albumin (BSA) scaffold through biomineralization. The resulting BSA–PtNPs have been proved to function as peroxidase mimics that can catalyze the reaction of various peroxidase substrates in the presence of H2O2. Kinetic studies indicate that BSA–PtNPs have a much higher affinity for H2O2 than the NPs of other Pt‐based peroxidase mimics. Furthermore, the BSA shell plays an important role in promoting the robust stability of PtNPs. Even in high ionic strength environment (2 M NaCl), the catalytic activity can be well preserved. These excellent properties make the BSA–PtNPs an ideal candidate for a wide range of potential applications as peroxidase mimics.
Assembly of a Nanoreactor System with Confined Magnetite Core and Shell for Enhanced Fenton‐Like Catalysis
Authors: Zeng Tao , Zhang Xiaole , Wang Saihua , Ma Yurong , Niu Hongyun , Cai Yaqi
Published: April 2014

Conventional solid catalysts for heterogeneous Fenton‐like reactions in bulk solution usually suffer from aggregation and vulnerability, which greatly lower the catalytic efficiency and hamper their practical application. Herein, we demonstrate a promising yolk–shell nanostructure with both the core and the shell composed of magnetite (designated as yolk‐like Fe3O4@Fe3O4/C) as a nanoreactor capable of accommodating the Fenton‐like reaction into its void space. Benefiting from the mesoporous shell and perfect interior cavity of this composite, reactants can access and be abundantly confined within the microenvironment where Fe3O4 sites are dispersed on the entire cavity surfaces, thus leading to a higher catalytic efficiency compared with the conventional solid catalysts in bulk solution. The chosen model reaction of chlorophenols degradation in the presence of the as‐prepared materials as well as hydrogen peroxide (H2O2) confirms this assumption. Under the optimal reaction conditions, more than 97 % 4‐chlorophenol (4‐CP) can be degraded in the Fe3O4@Fe3O4/C nanoreactor, whereas only 28 % can be achieved by using bare Fe3O4 particles within 60 min. Furthermore, owing to the existence of the outermost carbon layer and high‐magnetization properties, the nanoreactor can be re‐used for several runs. The synthesized nanoreactor displays superior catalytic activity toward the Fenton‐like reaction compared with the bare solid catalysts, and thereby holds significant potential for practical application in environmental remediation.
Azacyanines of the Pyrrolopyrrole Series
Authors: Marks Timo , Daltrozzo Ewald , Zumbusch Andreas
Published: April 2014

The reaction of POCl3‐activated, readily soluble diketopyrrolopyrrole (DPP) with 2‐aminoheteroaromatics to yield 1:1 and 1:2 hydrogen chelates is described. Complexation of these hydrogen chelates with boron reagents results in thermally and photochemically stable fluorescent dyes (PP–azacyanines). The 1:2 complexes in particular absorb at long wavelengths and are brightly fluorescing. The rich photophysics of the new compounds are presented. Both the pronounced vibrational fine structure of the S0→S1 transitions and the observed fluorescence phenomena allow detailed conclusions to be made on the correlation between molecular structure and optical properties.
A Compact Tetrathiafulvalene–Benzothiadiazole Dyad and Its Highly Symmetrical Charge‐Transfer Salt: Ordered Donor π‐Stacks Closely Bound to Their Acceptors
Authors: Geng Yan , Pfattner Raphael , Campos Antonio , Hauser Jürg , Laukhin Vladimir , Puigdollers Joaquim , Veciana Jaume , Mas‐Torrent Marta , Rovira Concepció , Decurtins Silvio , Liu Shi‐Xia
Published: April 2014

A compact and planar donor–acceptor molecule 1 comprising tetrathiafulvalene (TTF) and benzothiadiazole (BTD) units has been synthesised and experimentally characterised by structural, optical, and electrochemical methods. Solution‐processed and thermally evaporated thin films of 1 have also been explored as active materials in organic field‐effect transistors (OFETs). For these devices, hole field‐effect mobilities of μFE=(1.3±0.5)×10−3 and (2.7±0.4)×10−3 cm2 V s−1 were determined for the solution‐processed and thermally evaporated thin films, respectively. An intense intramolecular charge‐transfer (ICT) transition at around 495 nm dominates the optical absorption spectrum of the neutral dyad, which also shows a weak emission from its ICT state. The iodine‐induced oxidation of 1 leads to a partially oxidised crystalline charge‐transfer (CT) salt {(1)2I3}, and eventually also to a fully oxidised compound {1I3}⋅1/2I2. Single crystals of the former CT compound, exhibiting a highly symmetrical crystal structure, reveal a fairly good room temperature electrical conductivity of the order of 2 S cm−1. The one‐dimensional spin system bears compactly bonded BTD acceptors (spatial localisation of the LUMO) along its ridge.
Two‐Dimensional Assembly Based on Flow Supramolecular Chemistry: Kinetic Control of Molecular Interactions Under Solvent Diffusion
Authors: Numata Munenori , Kozawa Tomohiro
Published: April 2014

Self‐assembly of porphyrin molecules can be controlled kinetically to form structures with lengths extending from the nano‐ to the micrometer scale, through a programmed solvent‐diffusion process in designed microflow spaces. Temporal solvent structures generated in the microflow were successfully transcribed into molecular architectures.
Manganese(IV)‐Mediated Hydroperoxyarylation of Alkenes with Aryl Hydrazines and Dioxygen from Air
Authors: Kindt Stephanie , Jasch Hannelore , Heinrich Markus R.
Published: April 2014

We report a new carbooxygenation‐type version of the Meerwein arylation in which the introduction of oxygen is achieved by using dioxygen from the air. In this way, hydroperoxides were obtained from activated as well as non‐activated alkenes by oxidizing aryl hydrazines with manganese dioxide. The best results were obtained with α‐substituted acrylates. Importantly, the aryl hydrazine has to be added slowly to the reaction mixture to allow sufficient uptake of dioxygen from the air. Competition and labeling experiments revealed hydroperoxyl radicals as novel oxygen‐centered radical scavengers.
Synthesis and Structures of N‐Alkyl‐1,13‐dimethoxychromeno‐ [2,3,4‐kl]acridinium Salts: The Missing Azaoxa[4]helicenium
Authors: Sørensen Thomas Just , Madsen Anders Ø. , Laursen Bo W.
Published: April 2014

Helical structures are interesting due to their inherent chirality. Helicenium ions are triarylmethylium structures twisted into configurationally stable helicenes through the introduction of two heteroatom bridges between the three aryl substituents. Of the configurationally stable [4]helicenium ions, derivatives with sulfur, oxygen and nitrogen bridges have already been synthesised. However, one [4]helicenium ion has proven elusive, until now. We present herein the first synthesis of the 1,13‐dimethoxychromeno[2,3,4‐kl]acridinium (DMCA+) [4]helicenium ion. A series of six differently N‐substituted DMCA+ ions as their hexafluorophosphate salts are reported. Their cation stability was evaluated and it was found that DMCA+ is ideally suited as a phase‐transfer catalyst with a pKR+ of 13.0. The selectivity of nucleophilic addition to the central carbon atom of DMCA+ has been demonstrated with diastereotopic ratios of up to 1:10. The single‐crystal structures of several of the DMCA+ salts were determined, and structural differences between N‐aryl‐ and N‐alkyl‐substituted cations were observed. The results of a comparative study of the photophysics of the [4]helicenium ions are presented. DMCA+ is found to be a potent red‐emitting dye with a fluorescence quantum yield of 20 % in apolar solvents and a fluorescence lifetime of 12 ns. [4]Helicenium ions, including DMCA+, all suffer from solvent‐induced quenching, which reduces the fluorescence quantum yields significantly (ϕfl<5 %) in polar solvents. A difference in photophysical properties is observed between N‐aryl‐ and N‐alkyl‐substituted DMCA+, which has tentatively been attributed to a difference in molecular conformation.
Synthesis, π‐Face‐Selective Aggregation, and π‐Face Chiral Recognition of Configurationally Stable C3‐Symmetric Propeller‐Chiral Molecules with a π‐Core
Authors: Saito Nozomi , Terakawa Ryo , Yamaguchi Masahiko
Published: April 2014

The C3‐symmetric propeller‐chiral compounds (P,P,P)‐1 and (M,M,M)‐1 with planar π‐cores perpendicular to the C3‐axis were synthesized in optically pure states. (P,P,P)‐1 possesses two distinguishable propeller‐chiral π‐faces with rims of different heights named the (P/L)‐face and (P/H)‐face. Each face is configurationally stable because of the rigid structure of the helicenes contained in the π‐core. (P,P,P)‐1 formed dimeric aggregates in organic solutions as indicated by the results of 1H NMR, CD, and UV/Vis spectroscopy and vapor pressure osmometry analyses. The (P/L)/(P/L) interactions were observed in the solid state by single‐crystal X‐ray analysis, and they were also predominant over the (P/H)/(P/H) and (P/L)/(P/H) interactions in solution, as indicated by the results of 1H and 2D NMR spectroscopy analyses. The dimerization constant was obtained for a racemic mixture, which showed that the heterochiral (P,P,P)‐1/(M,M,M)‐1 interactions were much weaker than the homochiral (P,P,P)‐1/(P,P,P)‐1 interactions. The results indicated that the propeller‐chiral (P/L)‐face interacts with the (P/L)‐face more strongly than with the (P/H)‐face, (M/L)‐face, and (M/H)‐face. The study showed the π‐face‐selective aggregation and π‐face chiral recognition of the configurationally stable propeller‐chiral molecules.
Incorporating Polyoxometalates into a Porous MOF Greatly Improves Its Selective Adsorption of Cationic Dyes
Authors: Yan Ai‐Xue , Yao Shuang , Li Yang‐Guang , Zhang Zhi‐Ming , Lu Ying , Chen Wei‐Lin , Wang En‐Bo
Published: April 2014

Various polyoxometalates (POMs) were successfully immobilized to the mesoporous coordination polymer MIL‐101 resulting in a series of POM–MOF composite materials POM@MIL‐101 (POM=K4PW11VO40, H3PW12O40, K4SiW12O40). These materials were synthesized by a simple one‐pot reaction of Keggin POMs, tetramethylammonium hydroxide (TMAH), terephthalic acid (H2bdc), and Cr3+ ions. XRD, FTIR, thermogravimetric analyses (TG), inductively coupled plasma (ICP) spectrometry, and energy‐dispersive X‐ray spectroscopy (EDX) collectively confirmed the successful combination of POMs and the porous framework. Further, these composites POM@MIL‐101 with different loading of POMs were achieved by variation of the POM dosage. Notably, the uptake capacity of MIL‐101 towards organic pollutants in aqueous solution was significantly improved by immobilization of hydrophilic POMs into cages of MIL‐101. An uptake capacity of 371 mg g−1, comparable to that of the graphene oxide sponges, and much higher than that of the commercial activated carbon, was achieved at room temperature in 5 min when dipping 20 mg PW11V@MIL‐101 in the methylene blue (MB) solution (100 mL of 100 mg L−1 MB solution). Further study revealed that the POM@MIL‐101 composite materials not only exhibited a fast adsorption rate towards dye molecules, but also possessed of selective adsorption ability of the cationic dyes in wastewater. For example, the adsorption efficiency of PW11V@MIL‐101 (10 mg) towards MB (100 mL of 10 mg L−1) could reach 98 % in the initial 5 min, and it could capture MB dye molecules from the binary mixture of the MB and MO with similar size. Also, the POM@MIL‐101 materials could be readily recycled and reused, and no POM leached in the dye adsorption process.
Thermal Methane Activation by La6O10− Cluster Anions
Authors: Meng Jing‐Heng , Deng Xiao‐Jiao , Li Zi‐Yu , He Sheng‐Gui , Zheng Wei‐Jun
Published: April 2014

The first example of a metal oxide cluster anion, La6O10− that can activate methane under ambient conditions is reported. This reaction is facilitated by the oxygen‐centered radical (O−⋅) and follows the hydrogen atom transfer mechanism. The La6O10− has a high vertical electron detachment energy (VDE=4.06 eV) and a high symmetry (C4v).
A Two‐Armed Lanthanoid‐Chelating Paramagnetic NMR Probe Linked to Proteins via Thioether Linkages
Authors: Liu Wei‐Min , Skinner Simon P. , Timmer Monika , Blok Anneloes , Hass Mathias A. S. , Filippov Dmitri V. , Overhand Mark , Ubbink Marcellus
Published: April 2014

Paramagnetic NMR probes provide valuable long‐range structural information on proteins and protein complexes. A new, stable, two‐armed lanthanoid probe is reported that can be attached to a protein site‐specifically via chemically inert thioether linkages.
Facile Synthesis and Theoretical Conformation Analysis of a Triazine‐Based Double‐Decker Rotor Molecule with Three Anthracene Blades
Authors: Kory Max J. , Bergeler Maike , Reiher Markus , Schlüter A. Dieter
Published: April 2014

The facile synthesis of a rotor‐shaped compound with two stacked triazine units, which are symmetrically connected by three anthracene blades through oxygen linkers, is presented. This new double‐decker, which is a potential monomer for two‐dimensional polymerization, was synthesized by using readily available, cheap building blocks, exploiting the known selectivity difference for the nucleophilic substitution of cyanuric chloride. The crystal structure of a C3h symmetric rotor‐shaped compound with 9,10‐dihydroanthracene blades, which is a direct precursor to the targeted monomer, and the crystal structure of the new double‐decker with the desired C3h symmetry, are also reported. The synthetic efforts were preceded by a computational analysis, which was triggered by the question of conformational stability of the potential monomer. Two stable conformers could be found, and the barrier for the transition path in the gas phase between these conformers was determined by quantum chemical calculations. Exploratory Born–Oppenheimer molecular‐dynamics simulations revealed a strong influence of solvent–solute interactions on the stability of the conformers, which resulted in an energetic preference of the C3h symmetric conformation of the double‐decker.
Designed Single‐Step Synthesis, Structure, and Derivative Textural Properties of Well‐Ordered Layered Penta‐coordinate Silicon Alcoholate Complexes
Authors: Li Xiansen , Michaelis Vladimir K. , Ong Ta‐Chung , Smith Stacey J. , Griffin Robert G. , Wang Evelyn N.
Published: April 2014

The controllable synthesis of well‐ordered layered materials with specific nanoarchitecture poses a grand challenge in materials chemistry. Here the solvothermal synthesis of two structurally analogous 5‐coordinate organosilicate complexes through a novel transesterification mechanism is reported. Since the polycrystalline nature of the intrinsic hypervalent Si complex thwarts the endeavor in determining its structure, a novel strategy concerning the elegant addition of a small fraction of B species as an effective crystal growth mediator and a sacrificial agent is proposed to directly prepare diffraction‐quality single crystals without disrupting the intrinsic elemental type. In the determined crystal structure, two monomeric primary building units (PBUs) self‐assemble into a dimeric asymmetric secondary BU via strong Na+O2− ionic bonds. The designed one‐pot synthesis is straightforward, robust, and efficient, leading to a well‐ordered (10ī)‐parallel layered Si complex with its principal interlayers intercalated with extensive van der Waals gaps in spite of the presence of substantial Na+ counter‐ions as a result of unique atomic arrangement in its structure. However, upon fast pyrolysis, followed by acid leaching, both complexes are converted into two SiO2 composites bearing BET surface areas of 163.3 and 254.7 m2 g−1 for the pyrolyzed intrinsic and B‐assisted Si complexes, respectively. The transesterification methodology merely involving alcoholysis but without any hydrolysis side reaction is designed to have generalized applicability for use in synthesizing new layered metal–organic compounds with tailored PBUs and corresponding metal oxide particles with hierarchical porosity.
Oxygenated Metabolites of n‐3 Polyunsaturated Fatty Acids as Potential Oxidative Stress Biomarkers: Total Synthesis of 8‐F3t‐IsoP, 10‐F4t‐NeuroP and [D4]‐10‐F4t‐NeuroP
Authors: Guy Alexandre , Oger Camille , Heppekausen Johannes , Signorini Cinzia , De Felice Claudio , Fürstner Alois , Durand Thierry , Galano Jean‐Marie
Published: April 2014

A wide variety of metabolic products of polyunsaturated fatty acids is of paramount importance for improving our medical knowledge in the field of oxidized lipids. Two novel metabolites of n‐3 polyunsaturated fatty acids, 8‐F3t‐IsoP and 10‐F4t‐NeuroP as well as a deuterated derivative thereof were synthesized based on an acetylenic intermediate. An original approach achieved lateral chain insertion of 8‐F3t‐IsoP by a ring‐closing alkyne metathesis/semi‐reduction strategy together with a temporary tether.