bluuebunny/crossref_metadata_2025_split huggingface dataset:
Turbulence‐induced thermal signatures over evaporating bare soil surfaces
Authors: Haghighi Erfan , Or Dani 
Published: June 2015

AbstractSoil wetness and airflow turbulence are key factors affecting surface energy balance components thereby influencing surface skin temperature. Turbulent eddies interacting with evaporating surfaces often induce localized and intermittent evaporative and sensible heat fluxes that leave distinct thermal signatures. These surface thermal fluctuations observable by infrared thermography (IRT) offer a means for characterization of overlaying turbulent airflows and remote quantification of surface wetness. We developed a theoretical and experimental methodology for using rapid IR surface temperature measurements to deduce surface wetness and evaporative fluxes from smooth bare soils. The mechanistic model provides theoretical links between surface thermal fluctuations, soil, and aerodynamic properties enabling thermal inferences of soil wetness with explicit consideration of soil thermal capacity and airflow turbulence effects. The method potentially improves accuracy of soil wetness assessment by IRT‐based techniques whose performance is strongly influenced by surface‐turbulence interactions and offers new ways for quantifying fluxes directly at their origin.
Seasonal controls of canopy chlorophyll content on forest carbon uptake: Implications for GPP modeling
Authors: Croft H. , Chen J. M. , Froelich N. J. , Chen B. , Staebler R. M. 
Published: June 2015

AbstractForested ecosystems represent an important part of the global carbon cycle, with accurate estimates of gross primary productivity (GPP) crucial for understanding ecosystem response to environmental controls and improving global carbon models. This research investigated the relationships between leaf area index (LAI) and leaf chlorophyll content (ChlLeaf) with forest carbon uptake. Ground measurements of LAI and ChlLeaf were taken approximately every 9 days across the 2013 growing season from day of year (DOY) 130 to 290 at Borden Forest, Ontario. These biophysical measurements were supported by on‐site eddy covariance flux measurements. Differences in the temporal development of LAI and ChlLeaf were considerable, with LAI reaching maximum values within approximately 10 days of bud burst at DOY 141. In contrast, ChlLeaf accumulation only reached maximum values at DOY 182. This divergence has important implications for GPP models which use LAI to represent the fraction of light absorbed by a canopy (fraction of absorbed photosynthetic active radiation (fAPAR)). Daily GPP values showed the strongest relationship with canopy chlorophyll content (ChlCanopy; R2 = 0.69, p < 0.001), with the LAI and GPP relationship displaying nonlinearity at the start and end of the growing season (R2 = 0.55, p < 0.001). Modeled GPP derived from LAI × PAR and ChlCanopy × PAR was tested against measured GPP, giving R2 = 0.63, p < 0.001 and R2 = 0.82, p < 0.001, respectively. This work demonstrates the importance of considering canopy pigment status in deciduous forests, with models that use fAPARLAI rather than fAPARChl neglecting to account for the importance of leaf photosynthetic potential.
Estimating self‐clutter of the multiple‐pulse technique
Authors: Reimer A. S. , Hussey G. C. 
Published: June 2015

AbstractAutocorrelation function (ACF) estimates from voltage data measured by high‐frequency ionospheric radar systems that utilize the multiple‐pulse technique of Farley (1972) are susceptible to interference from self‐clutter. Self‐clutter is caused by simultaneous returns from multiple transmitted pulses echoing from unwanted, or ambiguous ranges. Without accurate estimates of self‐clutter it is impossible to account for all the uncertainty in estimates of the radar ACF. Voltage‐ and power‐based self‐clutter estimators are presented and evaluated using a modified version of the radar data simulator of Ribeiro et al. (2013a) and data from the Super Dual Auroral Radar Network (SuperDARN). It is shown that self‐clutter caused by ambiguous ranges filled with ground scatter can be accurately estimated using a voltage‐based self‐clutter estimator but that for ionospheric origin self‐clutter a maximal estimator must be used. Two maximal self‐clutter estimators are discussed and verified using the radar data simulator. A discussion of the application of the self‐clutter estimator as it is applied to ACFs obtained with Saskatoon SuperDARN radar is also presented.
Wave Optics
Authors: Dallas William J. 
Published: June 2015

Abstract
Narrowly interpreted, the term wave optics encompasses propagation, diffraction, and interference. Under a broader interpretation, wave optics includes those areas of optics governed by the electromagnetic wave equation. We begin with a brief review of the wave equation as it is built on the foundation of Maxwell's equations including some interaction of light with materials. We then look at polarization and chromatic composition in wave‐optical terms. Next is a translation of the wave equation into propagation relations organized under linear systems theory. We examine the propagation of optical waves from curved surfaces. An interesting and useful aspect of propagation is the existence of helical light; light that twists as it travels. We move on to interference and then diffraction. The hologram serves as an important example of interference, while the computer‐generated hologram is an example of control over diffraction. The Talbot effect, or Fourier self‐imaging, is a stunning example of the richness of propagation from diffractive optical elements. Finally, we discuss the subject of phase retrieval from irradiance distributions on multiple surfaces.
Die Chemie der Redox‐Flow‐Batterien
Authors: Noack Jens , Roznyatovskaya Nataliya , Herr Tatjana , Fischer Peter 
Published: June 2015

AbstractAufgrund der besonderen Eigenschaft der getrennten Skalierbarkeit von Energie und Leistung und der damit verbundenen potenziell niedrigen Energiespeicherkosten haben sich die Entwicklungen von unterschiedlichen Redox‐Flow‐Batterien zur Speicherung für fluktuierende erneuerbare Energien in den letzten Jahren intensiviert, was zu einem deutlichen Zuwachs an wissenschaftlicher Literatur geführt hat. Aus diesem Grund wird, anhand einer streng systematischen Einteilung und einem Fokus auf die Chemie der Elektrolyte, ein umfassender und kritischer Überblick über die Eigenschaften dieser Batterien und ihr zukünftiges Entwicklungspotenzial gegeben.
Metal‐Mediated Production of Isocyanates, R3ENCO from Dinitrogen, Carbon Dioxide, and R3ECl
Authors: Keane Andrew J. , Farrell Wesley S. , Yonke Brendan L. , Zavalij Peter Y. , Sita Lawrence R. 
Published: June 2015

AbstractA highly efficient and versatile chemical cycle has been developed for the production of isocyanates through the molecular fixation of N2, CO2 and R3ECl (E=C, Si, and Ge). Key steps include a ‘one‐pot’ photolytic NN bond cleavage of a Group 6 dinuclear dinitrogen complex with in situ trapping by R3ECl to provide a metal terminal imido complex that can engage in simultaneous nitrene‐group transfer and oxygen‐atom transfer to generate an intermediate metal terminal oxo complex with release of the isocyanate product. Reaction of the oxo complex with additional equivalents of R3ECl regenerates a metal dichloride that is the precursor for dinuclear dinitrogen starting material.
Diastereodivergente asymmetrische 1,4‐Addition von Oxindolen an Nitroolefine durch polyfunktionelle Nickel‐H‐Brücken‐Azolium‐ Katalysatoren
Authors: Mechler Melanie , Peters René 
Published: June 2015

AbstractDiastereodivergenz ist eine Herausforderung für die katalytische asymmetrische Synthese. Für viele Reaktionstypen ist die Bildung eines Diastereomers inhärent bevorzugt, während das andere Diastereomer nicht direkt und effizient zugänglich ist, sondern umständliche Syntheseumwege erfordert. Das Umgehen dieser natürlichen Präferenz mithilfe eines Katalysators erfordert die räumliche Kontrolle über beide Reaktionspartner. Wir stellen einen neuartigen, polyfunktionellen Katalysator vor, in dem eine NiII‐Bis(phenoxyimin)‐Einheit, freie Hydroxygruppen und ein axial‐chiraler Bisimidazolium‐Baustein an der Stereokontrolle der direkten 1,4‐Addition von Oxindolen an Nitroolefine beteiligt sind. Beide Epimere des 1,4‐Adduktes sind nach Belieben durch Variation der Konstitution und Konfiguration des Liganden zugänglich. Wie bereits berichtet wurde, sind die Produkte wertvolle Vorstufen für Indolalkaloide, und die vorliegende Methode sollte somit den Zugang zu den epimeren Derivaten eröffnen.
Kontakt zwischen den β1‐ und β2‐Segmenten von α‐Synuclein inhibiert die Amyloidbildung
Authors: Shaykhalishahi Hamed , Gauhar Aziz , Wördehoff Michael M. , Grüning Clara S. R. , Klein Antonia N. , Bannach Oliver , Stoldt Matthias , Willbold Dieter , Härd Torleif , Hoyer Wolfgang 
Published: June 2015

AbstractDie Umwandlung des intrinsisch ungeordneten Proteins α‐Synuclein (α‐syn) in Amyloidaggregate ist ein Schlüsselprozess der Parkinson‐Krankheit. Die Sequenzregion 35–59 enthält die β‐Strangsegmente β1 und β2 aus Strukturmodellen von α‐syn‐Amyloidfibrillen sowie die Mehrzahl der bekannten krankheitsassoziierten Mutationen. β1 und β2 gehen miteinander transiente Interaktionen in monomerem α‐syn ein. Hier untersuchen wir die Folgen von β1‐β2‐Kontakten mittels Disulfid‐Engineering, biophysikalischen Techniken und Zellviabilitäts‐Assays. Die Doppelcystein‐Mutante α‐synCC mit einer Disulfidbrücke zwischen β1 und β2 bildet keine Aggregate und inhibiert die Aggregation und Toxizität von Wildtyp‐α‐syn. Wir zeigen, dass α‐syn die Aggregation des Amyloid‐β‐Peptids und des Inselamyloid‐Polypeptids inhibiert, ein Effekt, der in der α‐synCC‐Mutante verstärkt ist. Tertiäre Interaktionen in der β1‐β2‐Region von α‐syn beeinträchtigen die Nukleation der Amyloidbildung. Ein therapeutischer Ansatz wäre folglich die Förderung solcher Interaktionen.
Hoch effiziente C‐SeCF3‐Kupplung von Aryliodiden durch einen luftbeständigen zweikernigen PdI‐Katalysator
Authors: Aufiero Marialuisa , Sperger Theresa , Tsang Althea S.‐K. , Schoenebeck Franziska 
Published: June 2015

AbstractAufbauend auf unseren jüngsten Entdeckungen bei zweikernigen PdI‐Komplexen beschreiben wir hier die Anwendung dieses Konzeptes zur Realisierung der ersten katalytischen Umwandlung von Aryliodiden zu ArSeCF3‐Verbindungen. Durch die Verwendung eines luft‐, feuchtigkeits‐ und temperaturbeständigen PdI‐Zweikernkomplexes konnte die hoch effiziente C‐SeCF3‐Kupplung einer Reihe von Aryliodiden erreicht werden. Ein neuer SeCF3‐verbrückter zweikerniger PdI‐Komplex 3 wurde isoliert, auf seine katalytische Kompetenz untersucht und als Katalysator wiederverwendet. Sowohl experimentelle als auch berechnete Resultate lassen auf einen Zweikern‐PdI‐Katalysemodus schließen.
Vier‐ und sechsfache Tandem‐Dominoreaktionen zur Synthese von dimeren tetrasubstituierten Alkenen als molekulare Doppelschalter
Authors: Tietze Lutz F. , Waldecker Bernd , Ganapathy Dhandapani , Eichhorst Christoph , Lenzer Thomas , Oum Kawon , Reichmann Sven O. , Stalke Dietmar 
Published: June 2015

AbstractEs wurde eine hocheffiziente Palladium‐katalysierte vierfache Tandem‐Dominoreaktion entwickelt, die zwei Carbopalladierungen und zwei C‐H‐Aktivierungen umfasst. Dabei wurden die helical‐chiralen tetrasubstituierten Alkene 3 und 6 ausgehend von den Substraten 1 und 4 erhalten. Die für den Aufbau der Ausgangsverbindung erforderliche Sonogashira‐Reaktion lässt sich zudem im Sinne einer sechsfachen Tandem‐Dominoreaktion integrieren. Es wurden 20 Verbindungen mit unterschiedlichen Substitutionsmustern in Ausbeuten von bis zu 97 % synthetisiert, und die helicale Chiralität der Verbindungen wurde durch Röntgenstrukturanalyse nachgewiesen. Photophysikalische Untersuchungen zeigen einen sehr schnellen lichtinduzierten Wechsel der stereochemischen Konfiguration.
Highly Robust Palladium(II) α‐Diimine Catalysts for Slow‐Chain‐Walking Polymerization of Ethylene and Copolymerization with Methyl Acrylate
Authors: Dai Shengyu , Sui Xuelin , Chen Changle 
Published: June 2015

AbstractA series of sterically demanding α‐diimine ligands bearing electron‐donating and electron‐withdrawing substituents were synthesized by an improved synthetic procedure in high yield. Subsequently, the corresponding Pd complexes were prepared and isolated by column chromatography. These Pd complexes demonstrated unique properties in ethylene polymerization, including high thermal stability and high activity, thus generating polyethylene with a high molecular weight and very low branching density. Similar properties were observed for ethylene/methyl acrylate copolymerization. Because of the high molecular weight and low branching density, the generated polyethylene and ethylene/methyl acrylate copolymer were semicrystalline solids. The (co)polymers had unique microstructures originating from the unique slow‐chain‐walking activity of these Pd complexes.
Mehrdimensionaler Entwurf von Antikrebspeptiden
Authors: Lin Yen‐Chu , Lim Yi Fan , Russo Erica , Schneider Petra , Bolliger Lea , Edenharter Adriana , Altmann Karl‐Heinz , Halin Cornelia , Hiss Jan A. , Schneider Gisbert 
Published: June 2015

AbstractWir stellen hier den rechnergestützten Entwurf und die Optimierung von Peptiden vor, die selektiv Krebszellen zerstören können. Der Designprozess ermöglichte die Verschmelzung von Eigenschaften bekannter Antikrebs‐, zellpenetrierender und Tumor‐adressierender Peptide. Dabei identifizierten maschinelle Lernverfahren vollautomatisch neue Peptide mit den vorhergesagten Eigenschaften. Ausgehend von einer als Vorlage fungierenden Aminosäuresequenz haben wir systematisch die Toxizität der Peptide gegen eine Reihe von Krebszelllinien optimiert, während gleichzeitig die Aktivität gegen primäre humane Endothelzellen reduziert wurde. Die vom Computer generierten Peptide zeigten verbesserte Krebszellpenetration, lösten Apoptose aus und waren in der Lage, die zytotoxisch wirksame Konzentration von gleichzeitig verabreichten Chemotherapeutika in vitro zu reduzieren. Diese Studie demonstriert das Potenzial mehrdimensionaler maschineller Lernverfahren, innerhalb kurzer Zeit neue Peptide mit den gewünschten Eigenschaften zu erhalten.
The Chemistry of Redox‐Flow Batteries
Authors: Noack Jens , Roznyatovskaya Nataliya , Herr Tatjana , Fischer Peter 
Published: June 2015

AbstractThe development of various redox‐flow batteries for the storage of fluctuating renewable energy has intensified in recent years because of their peculiar ability to be scaled separately in terms of energy and power, and therefore potentially to reduce the costs of energy storage. This has resulted in a considerable increase in the number of publications on redox‐flow batteries. This was a motivation to present a comprehensive and critical overview of the features of this type of batteries, focusing mainly on the chemistry of electrolytes and introducing a thorough systematic classification to reveal their potential for future development.
Structure‐Based Design of Inhibitors of Protein–Protein Interactions: Mimicking Peptide Binding Epitopes
Authors: Pelay‐Gimeno Marta , Glas Adrian , Koch Oliver , Grossmann Tom N. 
Published: June 2015

AbstractProtein–protein interactions (PPIs) are involved at all levels of cellular organization, thus making the development of PPI inhibitors extremely valuable. The identification of selective inhibitors is challenging because of the shallow and extended nature of PPI interfaces. Inhibitors can be obtained by mimicking peptide binding epitopes in their bioactive conformation. For this purpose, several strategies have been evolved to enable a projection of side chain functionalities in analogy to peptide secondary structures, thereby yielding molecules that are generally referred to as peptidomimetics. Herein, we introduce a new classification of peptidomimetics (classes A–D) that enables a clear assignment of available approaches. Based on this classification, the Review summarizes strategies that have been applied for the structure‐based design of PPI inhibitors through stabilizing or mimicking turns, β‐sheets, and helices.
Contact between the β1 and β2 Segments of α‐Synuclein that Inhibits Amyloid Formation
Authors: Shaykhalishahi Hamed , Gauhar Aziz , Wördehoff Michael M. , Grüning Clara S. R. , Klein Antonia N. , Bannach Oliver , Stoldt Matthias , Willbold Dieter , Härd Torleif , Hoyer Wolfgang 
Published: June 2015

AbstractConversion of the intrinsically disordered protein α‐synuclein (α‐syn) into amyloid aggregates is a key process in Parkinson’s disease. The sequence region 35–59 contains β‐strand segments β1 and β2 of α‐syn amyloid fibril models and most disease‐related mutations. β1 and β2 frequently engage in transient interactions in monomeric α‐syn. The consequences of β1–β2 contacts are evaluated by disulfide engineering, biophysical techniques, and cell viability assays. The double‐cysteine mutant α‐synCC, with a disulfide linking β1 and β2, is aggregation‐incompetent and inhibits aggregation and toxicity of wild‐type α‐syn. We show that α‐syn delays the aggregation of amyloid‐β peptide and islet amyloid polypeptide involved in Alzheimer’s disease and type 2 diabetes, an effect enhanced in the α‐synCC mutant. Tertiary interactions in the β1–β2 region of α‐syn interfere with the nucleation of amyloid formation, suggesting promotion of such interactions as a potential therapeutic approach.
Biosensing by Tandem Reactions of Structure Switching, Nucleolytic Digestion, and DNA Amplification of a DNA Assembly
Authors: Liu Meng , Zhang Wenqing , Zhang Qiang , Brennan John D. , Li Yingfu 
Published: June 2015

Abstractϕ29 DNA polymerase (ϕ29DP) is able to carry out repetitive rounds of DNA synthesis using a circular DNA template by rolling circle amplification (RCA). It also has the ability to execute 3′–5′ digestion of single‐stranded but not double‐stranded DNA. A biosensor engineering strategy is presented that takes advantage of these two properties of ϕ29DP coupled with structure‐switching DNA aptamers. The design employs a DNA assembly made of a circular DNA template, a DNA aptamer, and a pre‐primer. The DNA assembly is unable to undergo RCA in the absence of cognate target owing to the formation of duplex structures. The presence of the target, however, triggers a structure‐switching event that causes nucleolytic conversion of the pre‐primer by ϕ29DP into a mature primer to facilitate RCA. This method relays target detection by the aptamer to the production of massive DNA amplicons, giving rise to dramatically enhanced detection sensitivity.
Plasmonic Colloidosomes as Three‐Dimensional SERS Platforms with Enhanced Surface Area for Multiphase Sub‐Microliter Toxin Sensing
Authors: Phan‐Quang Gia Chuong , Lee Hiang Kwee , Phang In Yee , Ling Xing Yi 
Published: June 2015

AbstractColloidosomes are robust microcapsules attractive for molecular sensing because of their characteristic micron size, large specific surface area, and dual‐phase stability. However, current colloidosome sensors are limited to qualitative fluorogenic receptor‐based detection, which restrict their applicability to a narrow range of molecules. Here, we introduce plasmonic colloidosome constructed from Ag nanocubes as an emulsion‐based 3D SERS platform. The colloidosomes exhibit excellent mechanical robustness, flexible size tunability, versatility to merge, and ultrasensitivity in SERS quantitation of food/industrial toxins down to sub‐femtomole levels. Using just 0.5 μL of sample volumes, our plasmonic colloidosomes exhibit >3000‐fold higher SERS sensitivity over conventional suspension platform. Notably, we demonstrate the first high‐throughput multiplex molecular sensing across multiple liquid phases.
Reversible Switching of Redox‐Active Molecular Orbitals and Electron Transfer Pathways in CuA Sites of Cytochrome c Oxidase
Authors: Zitare Ulises , Alvarez‐Paggi Damián , Morgada Marcos N. , Abriata Luciano A. , Vila Alejandro J. , Murgida Daniel H. 
Published: June 2015

AbstractThe CuA site of cytochrome c oxidase is a redox hub that participates in rapid electron transfer at low driving forces with two redox cofactors in nearly perpendicular orientations. Spectroscopic and electrochemical characterizations performed on first and second‐sphere mutants have allowed us to experimentally detect the reversible switching between two alternative electronic states that confer different directionalities to the redox reaction. Specifically, the M160H variant of a native CuA shows a reversible pH transition that allows to functionally probe both states in the same protein species. Alternation between states exerts a dramatic impact on the kinetic redox parameters, thereby suggesting this effect as the mechanism underlying the efficiency and directionality of CuA electron transfer in vivo. These findings may also prove useful for the development of molecular electronics.
PdHx Entrapped in a Covalent Triazine Framework Modulates Selectivity in Glycerol Oxidation
Authors: Chan‐Thaw Carine E. , Villa Alberto , Wang Di , Santo Vladimiro Dal , Orbelli Biroli Alessio , Veith Gabriel M. , Thomas Arne , Prati Laura 
Published: June 2015

AbstractPd nanoparticles within a nitrogen‐containing covalent triazine framework (CTF) material are investigated to understand if the highly tunable CTF chemistry mediates the catalytic properties of the Pd nanoparticles. Surprisingly, our results demonstrate that the CTF stabilizes the formation of 2.6 nm PdHx particles within the pores. These confined PdHx particles are very active for the liquid‐phase oxidation of glycerol and promote CC cleavage, probably connected with the enhanced in situ formation of H2O2. During recycling tests, the confined particles are transformed progressively to very stable Pd0 particles. This stability has been attributed mainly to a confinement effect as nanoparticles trapped outside the pores lose activity rapidly. These results indicate that there is a potential to tune CTF chemistry to modify the chemistry of the catalytic metals significantly.
Galactose Oxidase Variants for the Oxidation of Amino Alcohols in Enzyme Cascade Synthesis
Authors: Herter Susanne , McKenna Shane M. , Frazer Andrew R. , Leimkühler Silke , Carnell Andrew J. , Turner Nicholas J. 
Published: June 2015

AbstractThe use of selected engineered galactose oxidase (GOase) variants for the oxidation of amino alcohols to aldehydes under mild conditions in aqueous systems is reported. GOase variant F2 catalyses the regioselective oxidation of N‐carbobenzyloxy (Cbz)‐protected 3‐amino‐1,2‐propanediol to the corresponding α‐hydroxyaldehyde which was then used in an aldolase reaction. Another variant, M3–5, was found to exhibit activity towards free and N‐Cbz‐protected aliphatic and aromatic amino alcohols allowing the synthesis of lactams such as 3,4‐dihydronaphthalen‐1(2H)‐one, 2‐pyrrolidone and valerolactam in one‐pot tandem reactions with xanthine dehydrogenase (XDH) or aldehyde oxidase (PaoABC).
Recent Developments in Palladium‐Based Bimetallic Catalysts
Authors: Liao Fenglin , Lo Tsz Woon Benedict , Tsang Shik Chi Edman 
Published: June 2015

AbstractAs one of the alternative metals to platinum, which supports a wide range of applications in chemistry and catalysis in industry, palladium increasingly receives attention because of its similar physicochemical properties. However, Pd is generally less expensive than Pt and has a richer natural reserve. Herein, some recently developed techniques for the preparation and characterization of Pd‐based bimetallic catalysts are reviewed. The impact on catalytic reactions of interest, including hydrogenation, dehydrogenation, hydrogenolysis, reforming, the oxygen reduction reaction, and hydrodesulfurization are also discussed. It is shown that the catalytic performance of Pd‐based bimetallic catalysts is strongly dependent on the geometric and electronic states of Pd, which can be significantly affected by blended foreign element(s). Rationalization of the structure–activity relationship can provide useful guidelines to the fine tuning of these important catalytic reactions.