bluuebunny/crossref_metadata_2025_split huggingface dataset:
Dielectric breakdown weathering of the Moon's polar regolith
Authors: Jordan A. P. , Stubbs T. J. , Wilson J. K. , Schwadron N. A. , Spence H. E. 
Published: January 2015

AbstractGalactic cosmic rays and solar energetic particles (SEPs) can charge the Moon's subsurface, a process expected to be particularly important in the polar regions. Experiments have shown that sufficient fluences (i.e., time‐integrated fluxes) of energetic charged particles can cause dielectric breakdown, in which the electric field rapidly vaporizes small, filamentary channels within a dielectric. Lunar regolith has both the characteristics and, in some polar locations, the environment needed to make breakdown likely. We combine the Jet Propulsion Laboratory proton fluence model with temperature measurements from the Lunar Reconnaissance Orbiter's (LRO's) Diviner instrument and related temperature modeling to estimate how often breakdown occurs in the polar regions. We find that all gardened regolith within permanently shadowed regions (PSRs) has likely experienced up to 2×106 SEP events capable of causing breakdown, while the warmest polar regions have experienced about 2 orders of magnitude fewer events. We also use measurements from the Cosmic Ray Telescope for the Effects of Radiation on LRO to show that at least two breakdown‐inducing events may have occurred since LRO arrived at the Moon in 2009. Finally, we discuss how such “breakdown weathering” may increase the percentage of fine and monomineralic grains within PSRs; explain the presence of so‐called “fairy castle” regolith structures; and contribute to other low‐albedo features detected by LRO's Lyman Alpha Mapping Project, possibly establishing a correlation between these features and the average temperatures within craters that are only partly in permanent shadow.
The Palladium Slow‐Release Pre‐Catalysts and Nanoparticles in the “Phosphine‐Free” Mizoroki–Heck and Suzuki–Miyaura Reactions
Authors: Sigeev Alexander S. , Peregudov Alexander S. , Cheprakov Andrei V. , Beletskaya Irina P. 
Published: January 2015

AbstractThe Mizoroki–Heck reaction of electron‐rich aryl iodides was studied using a phosphine‐free catalytic system with a broad range of pre‐catalysts of varied stability and structure based on organoselenium chelators. The application of the “mercury test” by observing the response of the catalytic systems studied not only to the addition, but also to the withdrawal of Hg allowed us to establish a critical role of nanoparticles in the operation of the phosphine‐free catalytic systems. A three‐stage mechanistic scheme involving a slow stage served by mononuclear Pd species, and the main fast stage served by Pd nanoparticles, and terminated by the nanoparticle decay is proposed as a general mechanistic paradigm for the phosphine‐free Mizoroki–Heck and the related Suzuki–Miyaura reactions.magnified image
Metal‐Organic Polyhedra: Catalysis and Reactive Intermediates
Authors: Vardhan Harsh , Verpoort Francis 
Published: January 2015

AbstractThe catalytic nature of self‐assembled metal‐organic polyhedra gives an entirely new dimension to the reactivity and properties of molecules within a well‐defined confined space. Encapsulation of a range of guests brings about not only host‐guest interactions but also gives rise to unusual reactivities with selectivity and stabilization of various reactive intermediates. This review briefly covers the synthesis of self‐assembled metal‐organic polyhedra and elaborates their influence in different chemical reactions as well as in the stabilization of unstable chemical species.magnified image
Tuning the Excited State of Water‐Soluble IrIII‐Based DNA Intercalators that are Isostructural with [RuII(NN)2(dppz)] Light‐Switch Complexes
Authors: Stimpson Sasha , Jenkinson Dan R. , Sadler Andrew , Latham Mark , Wragg Dr Ashley , Meijer Anthony J. H. M. , Thomas Jim A. 
Published: January 2015

AbstractThe synthesis of two new IrIII complexes which are effectively isostructural with well‐established [Ru(NN)2(dppz)]2+ systems is reported (dppz=dipyridophenazine; NN=2,2′‐bipyridyl, or 1,10‐phenanthroline). One of these IrIII complexes is tricationic and has a conventional N6 coordination sphere. The second dicationic complex has a N5C coordination sphere, incorporating a cyclometalated analogue of the dppz ligand. Both complexes show good water solubility. Experimental and computational studies show that the photoexcited states of the two complexes are very different from each other and also differ from their RuII analogues. Both of the complexes bind to duplex DNA with affinities that are two orders of magnitude higher than previously reported Ir(dppz)‐based systems and are comparable with RuII(dppz) analogues.
Micelle‐enhanced spectrofluorimetric determination of amlexanox in bioadhesive buccal tablets: application to content uniformity testing
Authors: Walash M. I. , Belal F. , Tolba M. M. , Halawa M. I. 
Published: January 2015

AbstractA highly sensitive, simple and rapid spectrofluorimetric method was developed for the determination of Amlexanox (AMX) in its bioadhesive buccal tablets. The proposed method is based on measuring the native fluorescence of the methanolic solution of AMX at 400 nm after excitation at 242 nm in 0.2 M borate buffer (pH 10) and 0.5% w/v sodium dodecyl sulfate (SDS) solution. The interaction of AMX with SDS was studied, and the enhanced fluorescence intensity was exploited to develop an assay method for the determination of AMX. The relative fluorescence intensity–concentration plot was rectilinear over the range 5.0–80.0 ng/mL, with a lower detection limit of 0.57 ng/mL and a lower quantification limit of 1.74 ng/mL. The proposed method was successfully applied to the analysis of AMX in its commercial tablets. Moreover, content uniformity testing was conducted by applying official USP guidelines. Statistical evaluation and comparison of the data obtained using the proposed and comparison methods revealed good accuracy and precision for the proposed method. Copyright © 2015 John Wiley & Sons, Ltd.
The preparation of ethylenediamine‐modified fluorescent carbon dots and their use in imaging of cells
Authors: Dong Wei , Zhou Siqi , Dong Yan , Wang Jingwen , Ge Xin , Sui Lili 
Published: January 2015

AbstractIn this work, fluorescent carbon dots (CDs) were synthesized using a hydrothermal method with glucose as the carbon source and were surface‐modified with ethylenediamine. The properties of as‐prepared CDs were analyzed by transmission electron microscopy (TEM), Fourier transform infrared (FTIR), ultraviolet–visible light (UV/vis) absorption and fluorescent spectra. Furthermore, CDs conjugated with mouse anti‐(human carcinoembryonic antigen) (CEA) monoclonal antibody were successful employed in the biolabeling and fluorescent imaging of human gastric carcinoma cells. In addition, the cytotoxicity of CDs was also tested using human gastric carcinoma cells. There was no apparent cytotoxicity on human gastric carcinoma cells. These results suggest the potential application of the as‐prepared CDs in bioimaging and related fields. Copyright © 2015 John Wiley & Sons, Ltd.
Luminescence of Eu and Ce in K3Ca2(SO4)3F fluoride material
Authors: Poddar Anuradha , Gedam S. C. , Dhoble S. J. 
Published: January 2015

AbstractA new halophosphor K3Ca2(SO4)3 F activated by Eu or Ce and K3Ca2(SO4)3 F:Ce,Eu co‐doped halosulfate phosphor has been synthesized by the co‐precipitation method and characterized for its photoluminescence (PL). The PL emission spectra of the K3Ca2(SO4)3 F :Ce phosphor show emission at 334 nm when excited at 278 nm due to 5d → 4f transition of Ce3+ ions. In the K3Ca2(SO4)3 F:Eu lattice, Eu2+ (440 nm) as well as Eu3+ (596 nm and 615 nm) emissions have been observed showing 5D0 → 7 F1 and 5D0 → 7 F2 transition of the Eu3+ ion, which is in the blue and red region of the visible spectrum respectively. The trivalent europium ion is very useful for studying the nature of metal coordination in various systems owing to its non‐degenerate emitting 5D0 state. K3Ca2(SO4)3 F:Ce,Eu is suitable for Ce3+ → Eu2+ → Eu3+ energy transfer in which Ce3+and Eu2+ play the role of sensitizers and Eu2+ and Eu3+ act as the activators. The observations presented in this paper are relevant for lamp phosphors. Copyright © 2015 John Wiley & Sons, Ltd.
Photoluminescence enhancement in Na3SO4Cl:X (X = Ce3+, Eu3+ or Dy3+) material
Authors: Shinde Nita , Dhoble N. S. , Gedam S. C. , Dhoble S. J. 
Published: January 2015

AbstractThe compound Na3SO4Cl X (X = Ce3+, Eu3+ or Dy3+) prepared by the wet chemical method was studied for its photoluminescence (PL) and energy transfer characteristics. The PL from Na3SO4Cl:Ce3+ shows strong emission at 322 nm at an excitation of 272 nm. Therefore, an efficient Ce3+ → Dy3+, Eu2+ → Dy3+ and Eu2+ → Eu3+ energy transfer had taken place in this host. The Dy3+ emission caused by Ce3+ → Dy3+ energy transfer under ultraviolet (UV) wavelengths peaked at around 477 nm and 572 nm due to 4 F9/2 → 6H15/2 and 6H13/2 transitions with yellow–orange emission in the Na3SO4Cl lattice. An intense Dy3+ emission was observed at 482 and 576 nm caused by the Eu2+ → Dy3+ energy transfer process and due to 4 F9/2 → 6H15/2 and 4 F9/2 → 6H13/2 transitions respectively. The Eu3+ blue to red light emission caused by the Eu2+ → Eu3+ energy transfer peaked at 593 nm and 617 nm due to 5D0 → 5D3 transitions. The presence of trivalent Eu in Na3SO4Cl suggested the presence of Eu3+ in the host compound that occupied two different lattice sites and that peaked at 593 and 617 nm due to 5D0 → 7 F1 and 5D0 → 7 F2 transitions respectively. The trivalent europium ion is very useful for studying the nature of metal coordination in various systems due to its non‐degenerate emitting 5D0 state. The present paper discusses the photoluminescence characteristics of Eu2+ → Dy3+ and Eu2+ → Eu3+ energy transfer. This compound may be useful as a lamp phosphor. Copyright © 2015 John Wiley & Sons, Ltd.
Purkinje cell responses during visually and vestibularly driven smooth eye movements in mice
Authors: Katoh Akira , Shin Soon‐Lim , Kimpo Rhea R. , Rinaldi Jacob M. , Raymond Jennifer L. 
Published: January 2015

AbstractIntroductionAn essential complement to molecular‐genetic approaches for analyzing the function of the oculomotor circuitry in mice is an understanding of sensory and motor signal processing in the circuit. Although there has been extensive analysis of the signals carried by neurons in the oculomotor circuits of species, such as monkeys, rabbits and goldfish, relatively little in vivo physiology has been done in the oculomotor circuitry of mice. We analyzed the contribution of vestibular and nonvestibular signals to the responses of individual Purkinje cells in the cerebellar flocculus of mice.MethodsWe recorded Purkinje cells in the cerebellar flocculus of C57BL/6 mice during eye movement responses to vestibular and visual stimulation.ResultsAs in other species, most individual Purkinje cells in mice carried both vestibular and nonvestibular signals, and the most common response across cells was an increase in firing in response to ipsiversive eye movement or ipsiversive head movement. When both the head and eyes were moving, the Purkinje cell responses were approximated as a linear summation of head and eye velocity inputs. Unlike other species, floccular Purkinje cells in mice were considerably more sensitive to eye velocity than head velocity.ConclusionsThe signal content of Purkinje cells in the cerebellar flocculus of mice was qualitatively similar to that in other species. However, the eye velocity sensitivity was higher than in other species, which may reflect a tuning to the smaller range of eye velocities in mice.
Comparison between one‐stent versus two‐stent technique for treatment of left main bifurcation lesions: A large single‐center data
Authors: Gao Zhan , Xu Bo , Yang Yuejin , Qiao Shubin , Wu Yongjian , Chen Tao , Xu Liang , Yuan Jinqing , Chen Jue , Gao Run‐lin 
Published: January 2015

BackgroundComparisons between one‐ and two‐stent strategies for unprotected left main (UPLM) coronary bifurcation disease have yielded inconsistent results. This large‐sample, long‐term follow‐up study comparatively assessed stenting strategy impact in patients with distal left main disease.MethodsTotally, 1,528 consecutive patients underwent left main percutaneous coronary intervention in a single center from January 2004 to December 2010 were enrolled; among them, 1033 patients with distal UPLM lesions treated by one (n = 661) or two (n = 372) drug‐eluting stent (DES) technique were comparatively analyzed. Primary outcome was rate of major adverse cardiovascular events (MACE), defined as a composite of death, myocardial infarction (MI), and target vessel revascularization (TVR).ResultsOverall, baseline SYNTAX score was low‐intermediate (one stent: 25 ± 6 vs. two stents: 26 ± 5, P = 0.02), and mean clinical SYNTAX score was similar between groups (one stent: 30 ± 22 vs. two stents: 31 ± 22, P = 0.47). Final kissing balloon was successfully achieved in most of the patients treated with two‐stent technique (one stent: 30.9% vs. two stents: 96.0%, P < 0.01), and use of intravascular ultrasound was also more common in them (one stent: 32.2% vs. two stents: 53.8%, P < 0.01). At mean 4 years follow‐up, rates of MACE (one stent: 9.2% vs. two stents: 11.6%, P = 0.23), death, MI, and TVR were similar between groups. In multivariate propensity‐matched regression analysis, two‐stent technique was not predictive of MACE.ConclusionsFor patients with distal UPLM disease and low‐intermediate SYNTAX score treated with DES, clinical outcomes appear similar between optimal two‐stent implantation and one‐stent strategy. © 2015 Wiley Periodicals, Inc.
Upper extremity deep vein thrombosis: a complication of an indwelling peripherally inserted central venous catheter
Authors: Carr Peter J. , Rippey James C. R. 
Published: January 2015

Key Clinical MessageWe report a case of peripherally inserted central venous catheter (PICC)‐associated deep vein thrombosis (DVT). Ultrasound images and video of subclavian thrombus are presented. PICC line‐associated DVT, particularly in cancer patients is not uncommon. Point‐of‐care Emergency Department ultrasound can readily diagnose this complication and device removal is not always necessary.
Triggering Activity of Catalytic Rod‐Like Supramolecular Polymers
Authors: Huerta Elisa , van Genabeek Bas , Lamers Brigitte A. G. , Koenigs Marcel M. E. , Meijer E. W. , Palmans Anja R. A. 
Published: January 2015

AbstractSupramolecular polymers based on benzene‐1,3,5‐tricarboxamides (BTAs) functionalized with an L‐ or D‐proline moiety display high catalytic activity towards aldol reactions in water. High turnover frequencies (TOF) of up to 27×10−4 s−1 and excellent stereoselectivities (up to 96 % de, up to 99 % ee) were observed. In addition, the catalyst could be reused and remained active at catalyst loadings and substrate concentrations as low as 0.1 mol % and 50 mM, respectively. A temperature‐induced conformational change in the supramolecular polymer triggers the high activity of the catalyst. The supramolecular polymer’s helical sense in combination with the configuration of the proline (L‐ or D‐) is responsible for the observed selectivity.
N‐Doped Carbon Networks: Alternative Materials Tracing New Routes for Activating Molecular Hydrogen
Authors: Cortese Remedios , Ferrante Francesco , Roggan Stefan , Duca Dario 
Published: January 2015

AbstractThe fragmentation of molecular hydrogen on N‐doped carbon networks was investigated by using molecular (polyaromatic macrocycles) as well as truncated and periodic (carbon nanotubes) models. The computational study was focused on the ergonicity analysis of the reaction and on the properties of the transition states involved when constellations of three or four pyridinic nitrogen atom defects are present in the carbon network. Calculations show that whenever N‐defects are embedded in species characterized by large conjugated π‐systems, either in polyaromatic macrocycles or carbon nanotubes, the corresponding H2 bond cleavage is largely exergonic. The fragmentation Gibbs free energy is affected by the final arrangement of the hydrogen atoms on the defect and by the extension of the π‐electron cloud, but it is not influenced by the curvature of the system.
Binary Polyazides of Cadmium and Mercury
Authors: Schulz Axel , Villinger Alexander 
Published: January 2015

AbstractFollowing our interest in binary element–nitrogen compounds we report here on the synthesis and comprehensive characterization (M.p., IR/Raman, elemental analysis, 14N/133Cd/199Hg NMR) of tri‐ and tetraazido cadmate and mercurate anions [E(N3)(2+n)]n− (E=Cd, Hg; n=1, 2) in a series of [Ph4P]+ and [PNP]+ ([PNP]+=bis(triphenylphosphine)iminium) salts. The azide/chloride exchange in CH2Cl2 as well as the formation of tetrazolate salts in CH3CN solutions of the polyazido mercurates were investigated. Single crystal X‐ray structures of all new compounds, and for comparison [Ph4P][Cd2(N3)5(H2O)], were determined. Moreover, the synthesis of anhydrous cadmium(II) azide and its DMSO adduct is presented for the first time. For a better understanding of structure and bonding in E(N3)2, [E(N3)3]− and [E(N3)4]2−, theoretical calculations at the M06‐2X/aug‐cc‐pVDZ level were carried out.
Synthesis of Fluorinated and Nonfluorinated Graphene Quantum Dots through a New Top‐Down Strategy for Long‐Time Cellular Imaging
Authors: Sun Hanjun , Ji Haiwei , Ju Enguo , Guan Yijia , Ren Jinsong , Qu Xiaogang 
Published: January 2015

AbstractHerein, a new strategy has been developed through combining a microwave‐assisted technique with hydrothermal treatment to reduce graphene waste and improve production yield of graphene quantum dots (GQDs) prepared by top‐down methods. By using fluorinated graphene oxide (FGO) as a raw material, fluorinated GQDs and nonfluorinated GQDs can be synthesized. Additionally, in the fluorinated GQDs, the protective shell supplied by fluorine improves the pH stability of photoluminescence and the strong electron‐withdrawing group, F, reduces the π‐ electron density of the aromatic structure; thus inhibiting reactivity toward singlet oxygen produced during irradiation and improving the photostability. Therefore, the as‐prepared fluorinated GQDs with excellent photo‐ and pH stability are suitable for long‐term cellular imaging.
Available energy of improper lossless LLTIP one‐ports
Authors: Sommariva Antonino M. 
Published: January 2015

SummaryA method for evaluating the available energy of a class of black‐box circuit components is proposed. The class consists of those linear lumped time‐invariant passive one‐ports of any order that are improper and lossless. The approach requires the utilization of tools and techniques from the calculus of variations (Euler–Lagrange equations and natural transversality conditions) and involves rather demanding algebraic and integro‐differential manipulations. However, the final formula for the available energy has the simple structure of a quadratic form in the one‐port external state vector, relatively easy to use or to implement. The various steps of the approach developed are illustrated through examples. Furthermore, to evidence the difference between available energy and stored energy, two degenerate and one non‐degenerate open‐box one‐ports are discussed in some detail. Copyright © 2015 John Wiley & Sons, Ltd.
Organocatalysis on Tap: Enantioselective Continuous Flow Processes Mediated by Solid‐Supported Chiral Organocatalysts
Authors: Rodríguez‐Escrich Carles , Pericàs Miquel A. 
Published: January 2015

AbstractSustainability concerns are reshaping the way chemists work, not only at the stage of process design, but also when actually performing reactions. This change in outlook is exemplified by the deployment of continuous flow techniques, which is slowly becoming mainstream practice. Indeed, the possibility of performing catalytic processes (the flagship of sustainable chemistry) in flow presents distinctive advantages. Thus, several authors are focusing their efforts on trying to get the best of these two worlds, with the consequent challenge of finding common solutions for their corresponding issues. In the last few years, this approach has been taken one step further with the use in flow processing of enantioselective organocatalysts, which allow the production of enantiopure compounds free of metal contaminants. Here we cover the literature relating to the use of solid‐supported organocatalysts for the continuous flow production of enantiomerically enriched compounds.
Enantioselective Synthesis, Crystal Structure, and Photophysical Properties of a 1,1′‐Bitriphenylene‐Based Sila[7]helicene
Authors: Murayama Koichi , Oike Yasuaki , Furumi Seiichi , Takeuchi Masayuki , Noguchi Keiichi , Tanaka Ken 
Published: January 2015

AbstractA 1,1′‐bitriphenylene‐based sila[7]helicene was synthesized with a high ee value by enantioselective double [2+2+2] cycloaddition of a biaryl‐linked tetrayne with a silicon‐linked bis(propargylic alcohol) as a key step. This sila[7]helicene exhibited a high tolerance toward racemization, which could be explained by the X‐ray crystal structure analysis. With respect to the photophysical properties, this sila[7]helicene exhibited a relatively high fluorescence quantum yield and circularly polarized luminescence activity.
Improved Synthesis of the Triazacryptand (TAC) and its Application in the Construction of a Fluorescent TAC‐BODIPY Conjugate for K+ Sensing in Live Cells
Authors: Sui Binglin , Yue Xiling , Tichy Michael G. , Liu Taihong , Belfield Kevin D. 
Published: January 2015

AbstractIn this report, a vastly improved method for the synthesis of [2.2.3]‐triazacryptand (TAC), an excellent K+‐selective cryptand, is disclosed, which provides a shorter synthetic route with > fivefold higher overall yield. On the basis of the improved synthesis, a TAC‐BODIPY conjugate was developed for K+ sensing. TAC‐BODIPY is a fluorescence turn‐on K+ sensor exhibiting high selectivity toward K+ over other biologically relevant metal cations. Cell imaging studies are presented and demonstrate that TAC‐BODIPY is suitable for dynamic K+ sensing in live cells.
Thiodisaccharide Sulfoxides: Absolute Configuration of the SO Sulfur Atom and Influence on the Biological Activity towards the β‐Galactosidase from E. coli
Authors: Colomer Juan P. , Canales Mayordomo María Ángeles , Fernández de Toro Beatriz , Jiménez‐Barbero Jesús , Varela Oscar 
Published: January 2015

AbstractBenzyl 3‐deoxy‐4‐S‐(β‐D‐galactopyranosyl)‐4‐thio‐β‐D‐threo‐pentopyranoside (3) is a potent inhibitor of the β‐galactosidase from Escherichia coli synthesized in our laboratory. The 2′,3′,4′,6′‐tetra‐O‐acetyl derivative of this thiodisaccharide was oxidized with m‐chloroperoxybenzoic acid to give a 2:1 diastereomeric mixture of sulfoxides 2S and 2R. The absolute configurations of their sulfur stereocenters were determined by using NMR techniques and by taking into account the anisotropic effects of the S=O group in the major conformers. O‐Deacetylation of 2S and 2R afforded the free thiodisaccharide S‐oxides 4S and 4R, which were evaluated as inhibitors of the above‐mentioned enzyme. The kinetic studies showed that 4S and 4R are competitive inhibitors of the enzyme with Ki values of 0.19 and 0.45 mM, respectively. Further enzymatic reactions demonstrated that 4S is also a substrate of the β‐galactosidase, as it was diastereoselectively hydrolyzed, with 4R remaining unchanged under the same conditions.
Alkyl Sulfinates: Formal Nucleophiles for Synthesizing TosMIC Analogs
Authors: Lujan‐Montelongo J. Armando , Estevez Angel Ojeda , Fleming Fraser F. 
Published: January 2015

AbstractAlkyl sulfinates function as formal nucleophiles in Mannich‐type reactions to give sulfonyl formamides, which are readily dehydrated to the corresponding sulfonylmethyl isonitriles. The efficient, two‐step synthesis provides a general route to sulfonylmethyl isonitriles from readily available methyl sulfinates or thiols. Mechanistic analysis reveals that the unusual nucleophlicity of the alkyl sulfinates arises from the in situ release of sulfinic acids.