bluuebunny/crossref_metadata_2025_split huggingface dataset:
Enhanced warming of the Northwest Atlantic Ocean under climate change
Authors: Saba Vincent S. , Griffies Stephen M. , Anderson Whit G. , Winton Michael , Alexander Michael A. , Delworth Thomas L. , Hare Jonathan A. , Harrison Matthew J. , Rosati Anthony , Vecchi Gabriel A. , Zhang Rong 
Published: December 2015

AbstractThe Intergovernmental Panel on Climate Change (IPCC) fifth assessment of projected global and regional ocean temperature change is based on global climate models that have coarse (∼100 km) ocean and atmosphere resolutions. In the Northwest Atlantic, the ensemble of global climate models has a warm bias in sea surface temperature due to a misrepresentation of the Gulf Stream position; thus, existing climate change projections are based on unrealistic regional ocean circulation. Here we compare simulations and an atmospheric CO2 doubling response from four global climate models of varying ocean and atmosphere resolution. We find that the highest resolution climate model (∼10 km ocean, ∼50 km atmosphere) resolves Northwest Atlantic circulation and water mass distribution most accurately. The CO2 doubling response from this model shows that upper‐ocean (0–300 m) temperature in the Northwest Atlantic Shelf warms at a rate nearly twice as fast as the coarser models and nearly three times faster than the global average. This enhanced warming is accompanied by an increase in salinity due to a change in water mass distribution that is related to a retreat of the Labrador Current and a northerly shift of the Gulf Stream. Both observations and the climate model demonstrate a robust relationship between a weakening Atlantic Meridional Overturning Circulation (AMOC) and an increase in the proportion of Warm‐Temperate Slope Water entering the Northwest Atlantic Shelf. Therefore, prior climate change projections for the Northwest Atlantic may be far too conservative. These results point to the need to improve simulations of basin and regional‐scale ocean circulation.
Dry season streamflow persistence in seasonal climates
Authors: Dralle David N. , Karst Nathaniel J. , Thompson Sally E. 
Published: December 2015

AbstractSeasonally dry ecosystems exhibit periods of high water availability followed by extended intervals during which rainfall is negligible and streamflows decline. Eventually, such declining flows will fall below the minimum values required to support ecosystem functions or services. The time at which dry season flows drop below these minimum values (Q*), relative to the start of the dry season, is termed the “persistence time” (
). The persistence time determines how long seasonal streams can support various human or ecological functions during the dry season. In this study, we extended recent work in the stochastic hydrology of seasonally dry climates to develop an analytical model for the probability distribution function (PDF) of the persistence time. The proposed model accurately captures the mean of the persistence time distribution, but underestimates its variance. We demonstrate that this underestimation arises in part due to correlation between the parameters used to describe the dry season recession, but that this correlation can be removed by rescaling the flow variables. The mean persistence time predictions form one example of the broader class of streamflow statistics known as crossing properties, which could feasibly be combined with simple ecological models to form a basis for rapid risk assessment under different climate or management scenarios.
Identifying long‐term empirical relationships between storm characteristics and episodic groundwater recharge
Authors: Tashie Arik M. , Mirus Benjamin B. , Pavelsky Tamlin M. 
Published: December 2015

AbstractShallow aquifers are an important source of water resources and provide base flow to streams; yet actual rates of groundwater recharge are difficult to estimate. While climate change is predicted to increase the frequency and magnitude of extreme precipitation events, the resulting impact on groundwater recharge remains poorly understood. We quantify empirical relations between precipitation characteristics and episodic groundwater recharge for a wide variety of geographic and land use types across North Carolina. We extract storm duration, magnitude, average rate, and hourly weighted intensity from long‐term precipitation records over periods of 12–35 years at 10 locations. Using time series of water table fluctuations from nearby monitoring wells, we estimate relative recharge to precipitation ratios (RPR) to identify statistical trends. Increased RPR correlates with increased storm duration, whereas RPR decreases with increasing magnitude, average rate, and intensity of precipitation. Agricultural and urban areas exhibit the greatest decrease in RPR due to increasing storm magnitude, average rate, and intensity, while naturally vegetated areas exhibit a larger increase in RPR with increased storm duration. Though RPR is generally higher during the winter than the summer, this seasonal effect is magnified in the Appalachian and Piedmont regions. These statistical trends provide valuable insights into the likely consequences of climate and land use change for water resources in subtropical climates. If, as predicted, growing seasons lengthen and the intensity of storms increases with a warming climate, decreased recharge in Appalachia, the Piedmont, and rapidly growing urban areas of the American Southeast could further limit groundwater availability.
A generalized complementary relationship between actual and potential evaporation defined by a reference surface temperature
Authors: Aminzadeh Milad , Roderick Michael L. , Or Dani 
Published: December 2015

AbstractThe definition of potential evaporation remains widely debated despite its centrality for hydrologic and climatic models. We employed an analytical pore‐scale representation of evaporation from terrestrial surfaces to define potential evaporation using a hypothetical steady state reference temperature that is common to both air and evaporating surface. The feedback between drying land surfaces and overlaying air properties, central in the Bouchet (1963) complementary relationship, is implicitly incorporated in the hypothetical steady state where the sensible heat flux vanishes and the available energy is consumed by evaporation. Evaporation rates predicted based on the steady state reference temperature hypothesis were in good agreement with class A pan evaporation measurements suggesting that evaporation from pans occurs with negligible sensible heat flux. The model facilitates a new generalization of the asymmetric complementary relationship with the asymmetry parameter b analytically predicted for a wide range of meteorological conditions with initial tests yielding good agreement between measured and predicted actual evaporation.
Computational Biology and Bioinformatics: Applications in Operations Research
Authors: Goulet Dave , Holder Allen 
Published: December 2015

AbstractThe innate optimal qualities exhibited by nature have fostered a host of applications for operations research in the biological sciences. The ongoing advance of the use of mathematical modeling and computing within the biological ethos has made dovetailing scientific pursuit with operations research a natural combination. Herein we present several biological problems in which either operations research has played a role or in which operations research is well poised to make an impact. The biological questions are selected to demonstrate the diverse scale over which biology drapes. Each problem begins with a terse biological introduction to establish the scientific setting, and the citations are selected to promote continued study.
Global adaptive finite‐time stabilization of a class of switched nonlinear systems with parametric uncertainty
Authors: Cai Mingjie , Xiang Zhengrong 
Published: December 2015

SummaryThis paper investigates the global adaptive finite‐time stabilization of a class of switched nonlinear systems, whose subsystems are all in p (p≤1) normal form with unknown control coefficients and parametric uncertainties. The restrictions on the power orders and the nonlinear perturbations are relaxed. By using the parameter separation technique, the uncertain parameters are separated from nonlinear functions. A systematic design procedure for a common state feedback controller and a switching adaptive law is presented by employing the backstepping methodology. It is proved that the closed‐loop system is finite‐time stable under arbitrary switching by utilizing the common Lyapunov function. Finally, with the application to finite‐time control of chemical reactor systems, the effectiveness of the proposed method is demonstrated. Copyright © 2015 John Wiley & Sons, Ltd.
Metal‐Free Synthesis of Chlorinated β‐Amino Ketones via an Unexpected Reaction of Imines with Arylacetylenes in 1,1,1,3,3,3‐Hexafluoro‐2‐propanol
Authors: Kushwaha Khushbu , Pinter Balazs , Shehzadi Syeda A. , Malakar Chandi C. , Vande Velde Christophe M. L. , de Proft Frank , Abbaspour Tehrani Kourosch 
Published: December 2015

AbstractThe metal‐free reaction of terminal arylacetylenes with α,α‐dichloroaldimines in 1,1,1,3,3,3‐hexafluoro‐2‐propanol as the sole solvent results in the rapid and selective formation of γ,γ‐dichloro‐β‐amino ketones. In this solvent the expected dichlorinated propargylamines and/or allylic amines are not formed. The dichloromethylene moiety of the aldimine acts as an activating group and is essential to accomplish this transformation. Electron‐rich acetylenes lead to the best results and work well with all imines (with or without α′‐H at the nitrogen substituent), while electron‐deficient acetylenes only reacted with N‐tert‐butylaldimines (no α′‐H). The mechanistic pathway showed 1,1,1,3,3,3‐hexafluoro‐2‐propanol to protonate the aldimine, which in the rate‐determining step will react with the arylacetylene to form a resonance‐stabilized allene cation, which is trapped by a HFIP molecule giving rise to an enol ether, which promptly hydrolyzes to furnish exclusively the β‐amino ketones. Using DFT techniques we found that the first CC bond forming step is the rate‐determining step and is associated with a barrier of about 21 kcal mol−1.magnified image
Regioselective Synthesis of 1,2‐ and 1,4‐Dihydroquinolines by Palladium‐Catalyzed Intramolecular N‐Arylation
Authors: Park Kyeong‐Yong , Lee Jinyong , Park Seong Jun , Heo Jung‐Nyoung , Lim Hwan Jung 
Published: December 2015

AbstractA series of 1,2‐ and 1,4‐dihydroquinolines has been successfully prepared. The Pd‐catalyzed intramolecular N‐arylation of Z‐enamines, formally prepared by the Horner–Wadsworth–Emmons olefination, proceeded efficiently to furnish the cyclized products. Depending on the cyclization conditions, substituted 1,4‐dihydroquinolines and further isomerized 1,2‐dihydroquinolines were independently obtained in high yields with an excellent control of isomerization of the double bond.magnified image
Phosphine‐Catalyzed Cascade Reaction of Unsaturated Pyrazolones with Alkyne Derivatives: Efficient Synthesis of Pyrano[2,3‐c]pyrazoles and Spiro‐cyclopentanone‐pyrazolones
Authors: Li Jun‐Hua , Du Da‐Ming 
Published: December 2015

AbstractA triphenylphosphine‐catalyzed cascade reaction of unsaturated pyrazolones with dialkyl acetylenedicarboxylates or but‐3‐yn‐2‐one to synthesize the bioactive pyrano[2,3‐c]pyrazoles in moderate to excellent yields has been developed. Meanwhile, spiro‐cyclopentanone‐pyrazolones were also first constructed by the triphenylphosphine‐catalyzed cascade reaction of unsaturated pyrazolones with 4‐phenylbut‐3‐yn‐2‐one in moderate to good yields.magnified image
Synthesis of Short‐Chain Alkenyl Ethers from Primary and Bio‐sourced Alcohols via the Nickel‐Catalyzed Hydroalkoxylation Reaction of Butadiene and Derivatives
Authors: Mifleur Alexis , Ledru Hélène , Lopes Adrien , Suisse Isabelle , Mortreux André , Sauthier Mathieu 
Published: December 2015

AbstractHydroalkoxylation of butadiene has been performed in the presence of nickel precatalysts associated with chelating diphosphine ligands. High butadiene conversions and selectivities forming alkyl butenyl ethers were obtained with low catalyst loading. Reactions were performed with a wide scope of primary alcohols including benzylic alcohol derivatives and bio‐sourced alcohols. In the same way, the scope of dienes that can be reacted according to this reaction has been also studied. Substituted butadiene derivatives have shown a lower reactivity compared to butadiene. Isoprene formed OC5 alkenyl ethers with a high regioselectivity for one branched isomeric form.magnified image
Rhodium(II)‐Catalyzed Regioselective Carbenoid Insertion Reaction of Simple Indoles with N‐Sulfonyltriazoles: A Rapid Access to Tryptamine Vinylogues
Authors: Huang Jiapian , Yang Yi , Chen Zhiyuan 
Published: December 2015

AbstractA synthetically useful 1,3‐insertion reaction of a rhodium‐carbenoid into the C(sp2)H bond of simple indole is disclosed, which produces structurally divergent 2‐indolylenamides in good to excellent yields and decent chemo‐ and regioselectivities. The obtained tryptamine vinylogues can be transformed into biologically important tryptamine derivatives or 3,3′‐biindoles with ease.magnified image
Novel Easily Recyclable Bifunctional Phosphonic Acid Carrying Tripeptides for the Stereoselective Michael Addition of Aldehydes with Nitroalkenes
Authors: Cortes‐Clerget Margery , Gager Olivier , Monteil Maelle , Pirat Jean‐Luc , Migianu‐Griffoni Evelyne , Deschamp Julia , Lecouvey Marc 
Published: December 2015

AbstractA novel bifunctional organocatalyst library combining both aminocatalysis and phosphonic acid activation was used for the first time as an efficient tool for the stereoselective Michael addition of aldehydes with several aromatic nitroalkenes with good selectivities up to 95:5 dr and 93:7 er. Due to their high water solubility, the catalysts were easily recyclable and could be reused over several cycles without any significant loss of selectivity.magnified image
Transformation of Contact‐Explosives Primary Amines and Iodine(III) into a Successful Chemical Reaction under Solvent‐Free Ball Milling Conditions
Authors: Kumar Achar Tapas , Mal Prasenjit 
Published: December 2015

AbstractAny synthetic transformation using contact‐explosives primary amines and hypervalent iodine(III) (phenyliodine diacetate) in constrained media (extreme conditions) is practically impossible. Herein, we report a method of controlling the explosion into a successful chemical reaction using the acid‐salt NaHSO4. As a proof‐of‐concept, we considered mechanochemical (ball‐milling) cross dehydrogenative coupling (CDC) reaction for the amidation of aldehydes via CH activation. An isothermal titration calorimetric (ITC) study was helpful to understand the enthalpy changes during the reactions before and after addition of NaHSO4.magnified image
Transformation of Trifluorotoluenes Triggered by Titanium(IV) Chloride‐Catalyzed Hydrodefluorination using Hydrosilanes
Authors: Yamada Takayuki , Saito Kodai , Akiyama Takahiko 
Published: December 2015

AbstractThe titanium tetrachloride‐catalyzed hydrodefluorination reaction of trifluorotoluene derivatives was developed using triethylsilane as the reducing agent. The reaction produced various toluene derivatives with high chemoselectivities by means of readily accessible reagents. This hydrodefluorination process was extended to the intramolecular Friedel–Crafts benzylation reaction, furnishing polycyclic aromatics of various ring sizes in good yields.magnified image
Electronic Energy Transfer Modulation in a Dynamic Foldaxane: Proof‐of‐Principle of a Lifetime‐Based Conformation Probe
Authors: Denisov Sergey A. , Gan Quan , Wang Xiang , Scarpantonio Luca , Ferrand Yann , Kauffmann Brice , Jonusauskas Gediminas , Huc Ivan , McClenaghan Nathan D. 
Published: December 2015

AbstractAbiotic aromatic oligoamide foldamers are shown to self‐assemble in solution to form a double helix, which can accommodate a bichromophoric thread in its central void. While in solution reversible electronic energy transfer is instilled between chromophoric termini of the free, flexible thread as evidenced through delayed luminescence, upon rigidification of the rod the chromophores are mutually distanced and effectively decoupled. Consequently, the chromophores display their individual photophysical characteristics. The observed conformation‐dependent changes of dynamic luminescence properties, which are particularly sensitive to distance, offers a new strategy for lifetime‐based detection of geometry on the molecular scale as demonstrated through real‐time luminescence detection of molecular complexation leading to foldaxane formation.
An Autonomously Reciprocating Transmembrane Nanoactuator
Authors: Watson Matthew A. , Cockroft Scott L. 
Published: December 2015

AbstractBiological molecular machines operate far from equilibrium by coupling chemical potential to repeated cycles of dissipative nanomechanical motion. This principle has been exploited in supramolecular systems that exhibit true machine behavior in solution and on surfaces. However, designed membrane‐spanning assemblies developed to date have been limited to simple switches or stochastic shuttles, and true machine behavior has remained elusive. Herein, we present a transmembrane nanoactuator that turns over chemical fuel to drive autonomous reciprocating (back‐and‐forth) nanomechanical motion. Ratcheted reciprocating motion of a DNA/PEG copolymer threaded through a single α‐hemolysin pore was induced by a combination of DNA strand displacement processes and enzyme‐catalyzed reactions. Ion‐current recordings revealed saw‐tooth patterns, indicating that the assemblies operated in autonomous, asymmetric cycles of conformational change at rates of up to one cycle per minute.
Heteroleptic [Bis(oxazoline)](dipyrrinato)zinc(II) Complexes: Bright and Circularly Polarized Luminescence from an Originally Achiral Dipyrrinato Ligand
Authors: Kögel Julius F. , Kusaka Shinpei , Sakamoto Ryota , Iwashima Toshiki , Tsuchiya Mizuho , Toyoda Ryojun , Matsuoka Ryota , Tsukamoto Takamasa , Yuasa Junpei , Kitagawa Yasutaka , Kawai Tsuyoshi , Nishihara Hiroshi 
Published: December 2015

AbstractHeteroleptic zinc(II) complexes synthesized using achiral dipyrrinato and chiral bis(oxazoline) ligands show bright fluorescence with quantum efficiencies of up to 0.70. The fluorescence originates from the 1π–π* photoexcited state localized exclusively on the dipyrrinato ligand. Furthermore, the luminescence is circularly polarized despite the achirality of the dipyrrinato ligand. Single‐crystal X‐ray structure analysis discloses that the chiral bis(oxazoline) ligand undergoes intramolecular π–π stacking with the dipyrrinato ligand, inducing axial chirality in the dipyrrinato moiety.
Catalytic Borylative Opening of Propargyl Cyclopropane, Epoxide, Aziridine, and Oxetane Substrates: Ligand Controlled Synthesis of Allenyl Boronates and Alkenyl Diboronates
Authors: Zhao Jian , Szabó Kálmán J. 
Published: December 2015

AbstractA new copper‐catalyzed reaction for the stereo‐ and regioselective synthesis of alkenyl diboronates and allenyl boronates is presented. In this process propargyl derivatives of strained three/four‐membered rings were employed as substrates and B2pin2 was used as the boronate source. Selective formation of the alkenyl diboronate versus the allenyl boronate products was controlled by the choice of phosphine ligand.
Inversion of the Supramolecular Chirality of Nanofibrous Structures through Co‐Assembly with Achiral Molecules
Authors: Liu Guo‐Feng , Zhu Ling‐Yun , Ji Wei , Feng Chuan‐Liang , Wei Zhi‐Xiang 
Published: December 2015

AbstractTo understand the behavior of chiral nanostructures, it is of critical importance to study how achiral molecules regulate the chirality of such nanostructures and what the main driving forces for the regulation processes are. In this work, the supramolecular chirality of helical nanofibers consisting of phenylalanine‐based enantiomers is inverted by achiral bis(pyridinyl) derivatives through co‐assembly. This inversion is mainly mediated by intermolecular hydrogen bonding interactions between the achiral additives and the chiral molecules, which may induce stereoselective interactions and different reorientations for the assembled molecules, as confirmed by calculations. This work not only exemplifies a feasible method to invert the helicity of chiral nanostructures by the addition of achiral molecules, but also provides a method to explore their functions in environments where chiral and achiral molecules are in close proximity.
Copper Hydride Catalyzed Hydroamination of Alkenes and Alkynes
Authors: Pirnot Michael T. , Wang Yi‐Ming , Buchwald Stephen L. 
Published: December 2015

AbstractOver the past few years, CuH‐catalyzed hydroamination has been discovered and developed as a robust and conceptually novel approach for the synthesis of enantioenriched secondary and tertiary amines. The success in this area of research was made possible through the large body of precedent in copper(I) hydride catalysis and the well‐explored use of hydroxylamine esters as electrophilic amine sources in related copper‐catalyzed processes. This Minireview details the background, advances, and mechanistic investigations in CuH‐catalyzed hydroamination.
Synthesis of Crystalline Chalcogenides in Ionic Liquids
Authors: Santner Silke , Heine Johanna , Dehnen Stefanie 
Published: December 2015

AbstractCrystalline chalcogenides belong to the most promising class of materials. In addition to dense solid‐state structures, they may form molecular cluster arrangements and networks with high porosity, as in the so‐called “zeotype” chalcogenidometalates. The high structural diversity comes along with interesting physical properties such as semi‐/photoconductivity, ion transport capability, molecular trapping potential, as well as chemical and catalytic activity. The great interest in the development of new and tailored chalcogenides has provoked a continuous search for new and better synthesis strategies over the years. The trend has clearly been towards lower temperatures for both economic and ecological reasons as well as for better reaction control. This led to the application of ionic liquids as a designer‐like medium for materials synthesis. In this Review, we summarize recent developments and present a survey of different chalcogenide families along with their properties.
Use of Trifluoromethyl Groups for Catalytic Benzylation and Alkylation with Subsequent Hydrodefluorination
Authors: Zhu Jiangtao , Pérez Manuel , Caputo Christopher B. , Stephan Douglas W. 
Published: December 2015

AbstractThe electrophilic organofluorophosphonium catalyst [(C6F5)3PF][B(C6F5)4] is shown to effect benzylation or alkylation by aryl and alkyl CF3 groups with subsequent hydrodefluorination, thus resulting in a net transformation of CF3 into CH2–aryl fragments. In the case of alkyl CF3 groups, Friedel–Crafts alkylation by the difluorocarbocation proceeded without cation rearrangement, in contrast to the corresponding reactions of alkyl monofluorides.