bluuebunny/crossref_metadata_2025_split huggingface dataset:
Phosphorites, Co‐rich Mn nodules, and Fe‐Mn crusts from Galicia Bank, NE Atlantic: Reflections of Cenozoic tectonics and paleoceanography
Authors: González Francisco Javier , Somoza Luis , Hein James R. , Medialdea Teresa , León Ricardo , Urgorri Victoriano , Reyes Jesús , Martín‐Rubí Juan Antonio 
Published: January 2016

AbstractA wide variety of marine mineral deposits were recovered from 750 to 1400 m water depths on Galicia Bank, Iberian margin. Mineral deposits include: (1) carbonate fluorapatite phosphorite slabs and nodules that replaced limestone and preserved original protolith fabric. (2) Ferromanganese vernadite crusts with high Mn and Fe (Mn/Fe = 1) contents, and thick stratabound layers consisting mainly of Mn (up to 27% MnO) and Fe (15% Fe2O3), which impregnated and replaced the phosphorite. (3) Co‐rich Mn nodules are composed of romanechite and todorokite laminae. Mn‐rich layers (up to 58% MnO) contain up to 1.8% Co. (4) Goethite nodules with Fe up to 67% Fe2O3 have low Mn and trace metals. We interpret this mineralization paragenesis to be related to major changes in oceanographic and tectonic regimes. Three phosphatization generations formed hardgrounds dated by 87Sr/86Sr isotopes as late Oligocene, early Miocene, and latest early Miocene. During the latest early Miocene, the hardground was fractured and breached due to regional intraplate tectonism, which was coeval with a widespread regional erosional unconformity. The stratabound layers and Co‐rich manganese nodules were derived from low‐temperature geothermally driven hydrothermal fluids, with fluid conduits along reactivated faults. During middle and late Miocene, the introduction of vigorous deep water flow from the Arctic generated growth of hydrogenetic ferromanganese crusts. Finally, growth of diagenetic Fe‐rich nodules (late Pliocene) was promoted by the introduction of hypersaline Mediterranean Outflow Water into the Atlantic Ocean.
Near‐ and far‐field tsunamigenic effects on the Z component of the geomagnetic field during the Japanese event, 2011
Authors: Klausner Virginia , Kherani Esfhan A. , Muella Marcio T. A. H. 
Published: February 2016

AbstractIn this work, we examine the vertical component (Z) of the geomagnetic field observed by ground‐based observatories during the tsunami event which happened on 11 March 2011. For this event, we have selected nine magnetic observatories distributed along the tsunami passage, covering up to 3000 km epicentral distance. The traveltime diagram of the magnetic disturbances is constructed and compared with the simulated tsunami traveltime diagram. From this comparison, we identify the amplified magnetic disturbances appearing during the tsunami arrival in the vicinity of these observatories. Moreover, mean absolute percentage error map is constructed to examine the cross correlations among different observatories and the amplified disturbances are found to be highly correlated. These features suggest that the amplified disturbances are tsunamigenic in nature. These results are in confirmation with the previous near‐field studies, and they shed new insight into the tsunamigenic magnetic disturbances on near‐ and far‐field distances from the epicenter.
Influence of vertical and lateral heat transfer on permafrost thaw, peatland landscape transition, and groundwater flow
Authors: Kurylyk Barret L. , Hayashi Masaki , Quinton William L. , McKenzie Jeffrey M. , Voss Clifford I. 
Published: January 2016

AbstractRecent climate change has reduced the spatial extent and thickness of permafrost in many discontinuous permafrost regions. Rapid permafrost thaw is producing distinct landscape changes in the Taiga Plains of the Northwest Territories, Canada. As permafrost bodies underlying forested peat plateaus shrink, the landscape slowly transitions into unforested wetlands. The expansion of wetlands has enhanced the hydrologic connectivity of many watersheds via new surface and near‐surface flow paths, and increased streamflow has been observed. Furthermore, the decrease in forested peat plateaus results in a net loss of boreal forest and associated ecosystems. This study investigates fundamental processes that contribute to permafrost thaw by comparing observed and simulated thaw development and landscape transition of a peat plateau‐wetland complex in the Northwest Territories, Canada from 1970 to 2012. Measured climate data are first used to drive surface energy balance simulations for the wetland and peat plateau. Near‐surface soil temperatures simulated in the surface energy balance model are then applied as the upper boundary condition to a three‐dimensional model of subsurface water flow and coupled energy transport with freeze‐thaw. Simulation results demonstrate that lateral heat transfer, which is not considered in many permafrost models, can influence permafrost thaw rates. Furthermore, the simulations indicate that landscape evolution arising from permafrost thaw acts as a positive feedback mechanism that increases the energy absorbed at the land surface and produces additional permafrost thaw. The modeling results also demonstrate that flow rates in local groundwater flow systems may be enhanced by the degradation of isolated permafrost bodies.
Insufficient disease inhibition by intrathecal rituximab in progressive multiple sclerosis
Authors: Komori Mika , Lin Yen Chih , Cortese Irene , Blake Andrew , Ohayon Joan , Cherup Jamie , Maric Dragan , Kosa Peter , Wu Tianxia , Bielekova Bibiana 
Published: February 2016

AbstractObjectiveInaccessibility of the inflammation compartmentalized to the central nervous system (CNS) may underlie the lack of efficacy of immunomodulatory treatments in progressive multiple sclerosis (MS). The double blind combination of Rituximab by IntraVenous and IntraThecAl injection versus placebo in patients with Low‐Inflammatory SEcondary progressive MS (RIVITALISE; NCT01212094) trial was designed to answer: (1) Whether an induction dose of intravenous and intrathecal rituximab efficiently depletes CNS B cells? and (2) If so, whether this leads to global inhibition of CNS inflammation and slowing of CNS tissue destruction?MethodsPatients aged 18–65 years were randomly assigned to rituximab or placebo. Protocol‐stipulated interim analysis quantified the efficacy of B‐cell depletion.ResultsThe efficacy on cerebrospinal fluid (CSF) biomarkers failed to reach criteria for continuation of the trial. B‐cell‐related CSF biomarkers (sCD21 and B‐cell activating factor) changed only in the active‐treatment arm. While CSF B cells were killed robustly (median −79.71%, P = 0.0176), B cells in CNS tissue were depleted inadequately (~−10–20%, P < 0.0001). Consequently, the T‐cell‐specific CSF biomarker sCD27 decreased slightly (−10.97%, P = 0.0005), while axonal damage marker, neurofilament light chain did not change. Insufficient saturation of CD20, lack of lytic complement, and paucity of cytotoxic CD56dim NK cells contribute to decreased efficacy of rituximab in the CNS.InterpretationBiomarker studies reliably quantified complementary pharmacodynamic effects of rituximab in the CNS, exposed causes for poor efficacy and determined that RIVITALISE trial would be underpowered to measure efficacy on clinical outcomes. Identified mechanisms for poor efficacy are applicable to all CNS‐inflammation targeting monoclonal antibodies.
Preparation and Characterization of Biodegradable Polyurethane Composites Containing Attapulgite Nanorods
Authors: Lee Hsun‐Tsing , Tsou Chi‐Hui , Li Chi‐Lan , Gu Jia‐Hao , Wu Cheng‐Lung , Hwang Jiunn‐Jer , Suen Maw‐Cherng 
Published: February 2016

ABSTRACTIn this study, polyurethane (PU) is synthesized using 4,4,‐diphenylmethane diisocyanate as the hard segments and polytetramethylene glycol and polycaprolactone diol as the soft segments. In addition, attapulgite (AT)/PU nanocomposites are prepared by adding AT into PU matrix.The structure and morphology of AT/PU nanocomposites are examined using transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT‐IR), X‐ray diffraction (XRD), and energy dispersive X‐ray spectroscopy (EDS). The TEM results show that AT maintains its rod‐like structure in the PU matrix. The FT‐IR results show that there is no significant change in the FT‐IR spectrum after a small amount of AT is added into the PU matrix. The XRD results show that the main crystallization peaks of AT become more apparent with increasing AT content, and the EDS results show that the intensity of the Si peak also increases with increasing AT content. In addition, the mapping shows that AT nanorods are poorly dispersed when the AT content reaches 5 wt%. The thermal and mechanical properties of the AT/PU nanocomposite with an AT content of 2 wt% are optimal, and when the AT content surpasses 5 wt%, an aggregation phenomenon occurs, resulting in reductions in the thermal and mechanical properties of the AT/PU nanocomposite. The contact angle test and atomic force microscopy results show that the surface of the nanocomposite becomes more rough and hydrophobic with increasing AT content. The scanning electron microscopy observations of the hydrolytic degradation of the AT/PU nanocomposites show that their hydrolytic degradation was affected by the test temperature, test time, and AT content. The moisture absorption test shows that the moisture absorption of the AT/PU nanocomposite increases with increasing AT content and ambient humidity.
19F NMR and DFT Analysis Reveal Structural and Electronic Transition State Features for RhoA‐Catalyzed GTP Hydrolysis
Authors: Jin Yi , Molt Robert W. , Waltho Jonathan P. , Richards Nigel G. J. , Blackburn G. Michael 
Published: January 2016

AbstractMolecular details for RhoA/GAP catalysis of the hydrolysis of GTP to GDP are poorly understood. We use 19F NMR chemical shifts in the MgF3− transition state analogue (TSA) complex as a spectroscopic reporter to indicate electron distribution for the γ‐PO3− oxygens in the corresponding TS, implying that oxygen coordinated to Mg has the greatest electron density. This was validated by QM calculations giving a picture of the electronic properties of the transition state (TS) for nucleophilic attack of water on the γ‐PO3− group based on the structure of a RhoA/GAP‐GDP‐MgF3− TSA complex. The TS model displays a network of 20 hydrogen bonds, including the GAP Arg85′ side chain, but neither phosphate torsional strain nor general base catalysis is evident. The nucleophilic water occupies a reactive location different from that in multiple ground state complexes, arising from reorientation of the Gln‐63 carboxamide by Arg85′ to preclude direct hydrogen bonding from water to the target γ‐PO3− group.
Solution Layer Deposition: A Technique for the Growth of Ultra‐Pure Manganese Oxides on Silica at Room Temperature
Authors: Cure Jérémy , Piettre Kilian , Coppel Yannick , Beche Eric , Esvan Jérôme , Collière Vincent , Chaudret Bruno , Fau Pierre 
Published: January 2016

AbstractWith the ever increasing miniaturization in microelectronic devices, new deposition techniques are required to form high‐purity metal oxide layers. Herein, we report a liquid route to specifically produce thin and conformal amorphous manganese oxide layers on silicon substrate, which can be transformed into a manganese silicate layer. The undesired insertion of carbon into the functional layers is avoided through a solution metal–organic chemistry approach named Solution Layer Deposition (SLD). The growth of a pure manganese oxide film by SLD takes place through the decoordination of ligands from a metal–organic complex in mild conditions, and coordination of the resulting metal atoms on a silica surface. The mechanism of this chemical liquid route has been elucidated by solid‐state 29Si MAS NMR, XPS, SIMS, and HRTEM.
Giant Amplification of Photoswitching by a Few Photons in Fluorescent Photochromic Organic Nanoparticles
Authors: Su Jia , Fukaminato Tuyoshi , Placial Jean‐Pierre , Onodera Tsunenobu , Suzuki Ryuju , Oikawa Hidetoshi , Brosseau Arnaud , Brisset François , Pansu Robert , Nakatani Keitaro , Métivier Rémi 
Published: January 2016

AbstractControlling or switching the optical signal from a large collection of molecules with the minimum of photons represents an extremely attractive concept. Promising fundamental and practical applications may be derived from such a photon‐saving principle. With this aim in mind, we have prepared fluorescent photochromic organic nanoparticles (NPs), showing bright red emission, complete ON–OFF contrast with full reversibility, and excellent fatigue resistance. Most interestingly, upon successive UV and visible light irradiation, the NPs exhibit a complete fluorescence quenching and recovery at very low photochromic conversion levels (<5 %), leading to the fluorescence photoswitching of 420±20 molecules for only one converted photochromic molecule. This “giant amplification of fluorescence photoswitching” originates from efficient intermolecular energy‐transfer processes within the NPs.
Der größte metalloide Cluster der 14. Gruppe, Ge18[Si(SiMe3)3]6: eine Zwischenstufe auf dem Weg zu elementarem Germanium
Authors: Kysliak Oleksandr , Schrenk Claudio , Schnepf Andreas 
Published: January 2016

AbstractDie Oxidation von [Ge9(Hyp)3]− (Hyp=Si(SiMe3)3) mit einem FeII‐Salz ergibt den größten metalloiden Cluster der 14. Gruppe, Ge18(Hyp)6 (1). Die Anordnung der 18 Germaniumatome in 1 zeigt dabei Ähnlichkeiten zur Festkörpermodifikation Ge(cF136). Zusätzlich kann 1 als makropolyedrischer Cluster zweier Ge9‐Einheiten aufgefasst werden. Quantenchemische Rechnungen weisen auf ein gespanntes System hin, sodass 1 als eine erste abgefangene Zwischenstufe, ausgehend von Ge9‐Einheiten, hin zu elementarem Germanium in der Clathrat(II)‐Struktur Ge(cF136), aufgefasst werden kann.
Macrocyclic Transformations from Norrole to Isonorrole and an N‐Confused Corrole with a Fused Hexacyclic Ring System Triggered by a Pyrrole Substituent
Authors: Li Miao , Wei Pingchun , Ishida Masatoshi , Li Xin , Savage Mathew , Guo Rui , Ou Zhongping , Yang Sihai , Furuta Hiroyuki , Xie Yongshu 
Published: January 2016

AbstractThree kinds of fused porphyrinoids, L2–L4, possessing different types of corrole‐based frameworks were synthesized from a pyrrole‐substituted corrole isomer (norrole L1). Oxidation of L1 afforded a unique N‐Cmeso‐fused pyrrolyl isonorrole L2, involving the fusion of an auxiliary pyrrolic NH moiety with a meso‐sp3‐hybridized carbon atom. Subsequently, L2 underwent macrocycle transformations to give singly and doubly N‐CAr‐fused N‐confused corroles, L3 and L4, respectively. L3 and L4 contain fused [5.7.6.5]‐tetra‐ and [5.6.7.7.6.5]‐hexacyclic structures, respectively, prepared through lateral annulation. These skeletal transformation reactions from norrole to its isomer isonorrole and finally to N‐confused corrole indicate that multiply fused porphyrinoids could be readily synthesized from pyrrole‐appended confused porphyrinoids.
Layered Black Phosphorus: Strongly Anisotropic Magnetic, Electronic, and Electron‐Transfer Properties
Authors: Sofer Zdeněk , Sedmidubský David , Huber Štěpán , Luxa Jan , Bouša Daniel , Boothroyd Chris , Pumera Martin 
Published: January 2016

AbstractLayered elemental materials, such as black phosphorus, exhibit unique properties originating from their highly anisotropic layered structure. The results presented herein demonstrate an anomalous anisotropy for the electrical, magnetic, and electrochemical properties of black phosphorus. It is shown that heterogeneous electron transfer from black phosphorus to outer‐ and inner‐sphere molecular probes is highly anisotropic. The electron‐transfer rates differ at the basal and edge planes. These unusual properties were interpreted by means of calculations, manifesting the metallic character of the edge planes as compared to the semiconducting properties of the basal plane. This indicates that black phosphorus belongs to a group of materials known as topological insulators. Consequently, these effects render the magnetic properties highly anisotropic, as both diamagnetic and paramagnetic behavior can be observed depending on the orientation in the magnetic field.
Influence of Equatorial CH⋅⋅⋅O Interactions on Secondary Kinetic Isotope Effects for Methyl Transfer
Authors: Wilson Philippe B. , Williams Ian H. 
Published: January 2016

AbstractDFT calculations for methyl cation complexed within a constrained cage of water molecules permit the controlled manipulation of the “axial” donor/acceptor distance and the “equatorial” distance to hydrogen‐bond acceptors. The kinetic isotope effect k(CH3)/k(CT3) for methyl transfer within a cage with a short axial distance becomes less inverse for shorter equatorial C⋅⋅⋅O distances: a decrease of 0.5 Å results in a 3 % increase at 298 K. Kinetic isotope effects in AdoMet‐dependent methyltransferases may be m∧odulated by CH⋅⋅⋅O hydrogen bonding, and factors other than axial compression may contribute, at least partially, to recently reported isotope‐effect variations for catechol‐O‐methyltransferase and its mutant structures.
Directly Diphenylborane‐Fused Porphyrins
Authors: Fujimoto Keisuke , Oh Juwon , Yorimitsu Hideki , Kim Dongho , Osuka Atsuhiro 
Published: January 2016

AbstractMono‐ and bis(diphenylborane)‐fused porphyrins were synthesized from the corresponding β‐(2‐trimethylsilylphenyl)‐substituted porphyrins through the sequence of Si–B exchange reaction, intramolecular bora‐Friedel–Crafts reaction, and ring‐closing Si–B exchange reaction. Effective electronic interactions of the empty p‐orbital of the boron atom with the porphyrin π‐circuit lead to red‐shifted absorption spectra and substantially decreased LUMO energy levels. Pyridine adds at the boron center to cause disruption of the electronic interaction of the boron atom with large association constants (1.9–17×104 m−1) depending on the central metal at the porphyrin. The ZnII complex behaved as a hetero‐dinuclear Lewis acid, exhibiting regioselective binding of pyridines at the boron or the zinc center.
Syntheses and Promising Properties of Dense Energetic 5,5′‐Dinitramino‐3,3′‐azo‐1,2,4‐oxadiazole and Its Salts
Authors: Tang Yongxing , Gao Haixiang , Mitchell Lauren A. , Parrish Damon A. , Shreeve Jean'ne M. 
Published: January 2016

AbstractA planar energetic molecule with high density, 5,5′‐dinitramino‐3,3′‐azo‐1,2,4‐oxadiazole (4), was obtained by the nitration of 5,5′‐diamino‐3,3′‐azo‐1,2,4‐oxadiazole using 100 % nitric acid. In addition, selected nitrogen‐rich salts were prepared. Of them, the neutral compound 4 and its hydroxylammonium salt, 6, were further confirmed by single‐crystal X‐ray diffraction. Physicochemical and energetic properties including density, thermal stability, and sensitivity were investigated. The energetic performance from the calculated heats of formation and experimental densities indicates that many of them have potential applications as energetic materials.
Mussel‐Directed Synthesis of Nitrogen‐Doped Anatase TiO2
Authors: Xie Jingjing , Xie Hao , Su Bao‐Lian , Cheng Yi‐bing , Du Xiaodong , Zeng Hui , Wang Menghu , Wang Weimin , Wang Hao , Fu Zhengyi 
Published: January 2016

AbstractStructure‐forming processes leading to biominerals are well worth learning in pursuit of new synthetic techniques. Strategies that attempt to mimic nature in vitro cannot replace an entire complex natural organism, requiring ingenuity beyond chemists′ hands. A “bioprocess‐inspired synthesis” is demonstrated for fabrication of N‐doped TiO2 materials at ambient temperature by direct implantation of precursor into living mussels. The amorphous precursor transforms into N‐doped anatase TiO2 with a hierarchical nanostructure. Synthetic TiO2 exhibits high phase stability and enhanced visible‐light photocatalytic activity as a result of modifications to its band gap during in vivo mineralization. Intracellular proteins were found to be involved in TiO2 mineralization. Our findings may inspire material production by new synthetic techniques, especially under environmentally benign conditions.
Hydroxylation versus Halogenation of Aliphatic C−H Bonds by a Dioxygen‐Derived Iron–Oxygen Oxidant: Functional Mimicking of Iron Halogenases
Authors: Chatterjee Sayanti , Paine Tapan Kanti 
Published: January 2016

AbstractAn iron–oxygen intermediate species generated in situ in the reductive activation of dioxygen by an iron(II)–benzilate complex of a monoanionic facial N3 ligand, promoted the halogenation of aliphatic C−H bonds in the presence of a protic acid and a halide anion. An electrophilic iron(IV)–oxo oxidant with a coordinated halide is proposed as the active oxidant. The halogenation reaction with dioxygen and the iron complex mimics the activity of non‐heme iron halogenases.
A Cobalt(I) Pincer Complex with an η2‐Caryl−H Agostic Bond: Facile C−H Bond Cleavage through Deprotonation, Radical Abstraction, and Oxidative Addition
Authors: Murugesan Sathiyamoorthy , Stöger Berthold , Pittenauer Ernst , Allmaier Günter , Veiros Luis F. , Kirchner Karl 
Published: January 2016

AbstractThe synthesis and reactivity of a CoI pincer complex [Co(ϰ3P,CH,P‐P(CH)PNMe‐iPr)(CO)2]+ featuring an η2‐ Caryl−H agostic bond is described. This complex was obtained by protonation of the CoI complex [Co(PCPNMe‐iPr)(CO)2]. The CoIII hydride complex [Co(PCPNMe‐iPr)(CNtBu)2(H)]+ was obtained upon protonation of [Co(PCPNMe‐iPr)(CNtBu)2]. Three ways to cleave the agostic C−H bond are presented. First, owing to the acidity of the agostic proton, treatment with pyridine results in facile deprotonation (C−H bond cleavage) and reformation of [Co(PCPNMe‐iPr)(CO)2]. Second, C−H bond cleavage is achieved upon exposure of [Co(ϰ3P,CH,P‐P(CH)PNMe‐iPr)(CO)2]+ to oxygen or TEMPO to yield the paramagnetic CoII PCP complex [Co(PCPNMe‐iPr)(CO)2]+. Finally, replacement of one CO ligand in [Co(ϰ3P,CH,P‐P(CH)PNMe‐iPr)(CO)2]+ by CNtBu promotes the rapid oxidative addition of the agostic η2‐Caryl−H bond to give two isomeric hydride complexes of the type [Co(PCPNMe‐iPr)(CNtBu)(CO)(H)]+.
Multicomponent Diene‐Transmissive Diels–Alder Sequences Featuring Aminodendralenes
Authors: Tan Siu Min , Willis Anthony C. , Paddon‐Row Michael N. , Sherburn Michael S. 
Published: January 2016

Abstract1‐Aminodecalins were prepared from acyclic precursors by combining the powerful twofold diene‐transmissive Diels–Alder chemistry of [3]dendralenes with the simplicity of enamine formation. On mixing at ambient temperature, a simple dienal condenses with a primary or secondary amine to generate the enamine, a 1‐amino‐[3]dendralene in situ, and this participates as a double diene in a sequence of two Diels–Alder events with separate dienophiles. Overall, four C−C bonds and one C−N bond are formed. Mechanistic insights into these reactions are provided by means of density functional theory calculations.
A Triatomic Silicon(0) Cluster Stabilized by a Cyclic Alkyl(amino) Carbene
Authors: Mondal Kartik Chandra , Roy Sudipta , Dittrich Birger , Andrada Diego M. , Frenking Gernot , Roesky Herbert W. 
Published: January 2016

AbstractReduction of the neutral carbene tetrachlorosilane adduct (cAAC)SiCl4 (cAAC=cyclic alkyl(amino) carbene :C(CMe2)2(CH2)N(2,6‐iPr2C6H3) with potassium graphite produces stable (cAAC)3Si3, a carbene‐stabilized triatomic silicon(0) molecule. The Si−Si bond lengths in (cAAC)3Si3 are 2.399(8), 2.369(8) and 2.398(8) Å, which are in the range of Si−Si single bonds. Each trigonal pyramidal silicon atom of the triangular molecule (cAAC)3Si3 possesses a lone pair of electrons. Its bonding, stability, and electron density distributions were studied by quantum chemical calculations.