bluuebunny/crossref_metadata_2025_split huggingface dataset:
Limitations on silicon in the outer core: Ultrasonic measurements at high temperatures and high dK/dP values of Fe‐Ni‐Si liquids at high pressures
Authors: Williams Quentin , Manghnani Murli H. , Secco Richard A. , Fu Shunsheng 
Published: September 2015

AbstractThe sound velocities of four iron‐nickel‐silicon liquids (Fe‐5 wt %Ni‐6 wt %Si, Fe‐5 wt %Ni‐10 wt %Si, Fe‐5 wt %Ni‐14 wt %Si, and Fe‐5 wt %Ni‐20 wt %Si) are measured between 1460 and 1925 K at ambient pressures using ultrasonic interferometry. The results constrain both the dependence on Si content of the bulk modulus of these liquids and the temperature dependence of their elasticity. These elastic data are utilized to assess both relatively low pressure (to 12 GPa) compressional data on Fe‐Si liquids and to extrapolate to higher‐pressure and higher‐temperature conditions. If a single equation of state for Fe‐Ni‐Si liquids of a given composition applies from low pressure to near core conditions, then our results imply that the isothermal pressure derivative of the bulk modulus of these liquids is high: likely 8 and above at high temperatures. This high value of the pressure derivative of the bulk modulus at low pressures in Fe‐Si liquids causes marked stiffening at higher pressures, leading to notable incompressibility and apparent low values of the pressure derivative of the bulk modulus at core conditions. These results reinforce the conclusion that silicon is not a major alloying component of Earth's core.
Low‐cloud characteristics over the tropical western Pacific from ARM observations and CAM5 simulations
Authors: Chandra Arunchandra S. , Zhang Chidong , Klein Stephen A. , Ma Hsi‐Yen 
Published: September 2015

AbstractThis study evaluates the ability of the Community Atmospheric Model version 5 (CAM5) to reproduce low clouds observed by the Atmospheric Radiation Measurement (ARM) cloud radar at Manus Island of the tropical western Pacific during the Years of Tropical Convection. Here low clouds are defined as clouds with their tops below the freezing level and bases within the boundary layer. Low‐cloud statistics in CAM5 simulations and ARM observations are compared in terms of their general occurrence, mean vertical profiles, fraction of precipitating versus nonprecipitating events, diurnal cycle, and monthly time series. Other types of clouds are included to put the comparison in a broader context. The comparison shows that the model overproduces total clouds and their precipitation fraction but underestimates low clouds in general. The model, however, produces excessive low clouds in a thin layer between 954 and 930 hPa, which coincides with excessive humidity near the top of the mixed layer. This suggests that the erroneously excessive low clouds stem from parameterization of both cloud and turbulence mixing. The model also fails to produce the observed diurnal cycle in low clouds, not exclusively due to the model coarse grid spacing that does not resolve Manus Island. This study demonstrates the utility of ARM long‐term cloud observations in the tropical western Pacific in verifying low clouds simulated by global climate models, illustrates issues of using ARM observations in model validation, and provides an example of severe model biases in producing observed low clouds in the tropical western Pacific.
Proteoglycans and Acidic Polysaccharides Analysis
Authors: Lauder Robert M. 
Published: September 2015

AbstractThe study of the structure and function of proteoglycans (PGs) and glycosaminoglycans (GAGs) has assumed an increasing significance as the wide range of important biological processes in which they play central roles has been elucidated. As studies of GAG structure expand in scope, and detail, the full structural diversity of these polymers is being uncovered. Significant heterogeneity can be seen but relationships with development, age, and pathology are being uncovered, which place these macromolecules centrally in these processes.Available methodologies allow detailed analysis of GAGs, but careful attention to the sample requirements of these methods and to their limitations is required to ensure the quality and reliability of the data derived is assured. Important developments, including mass spectrometry approaches, will take the field forward but well‐established methods for the isolation and characterization of these complex molecules continue to have a hugely important role to play in structural and functional studies.This article examines a wide range of methodologies for the isolation and characterization of the PGs and GAGs in which recent developments in the field are reported along with well‐established methods for the characterization of entire GAG chains or discrete features within those.
Characterization of IgG4 anti‐neurofascin 155 antibody‐positive polyneuropathy
Authors: Ogata Hidenori , Yamasaki Ryo , Hiwatashi Akio , Oka Nobuyuki , Kawamura Nobutoshi , Matsuse Dai , Kuwahara Motoi , Suzuki Hidekazu , Kusunoki Susumu , Fujimoto Yuichi , Ikezoe Koji , Kishida Hitaru , Tanaka Fumiaki , Matsushita Takuya , Murai Hiroyuki , Kira Jun‐ichi 
Published: September 2015

AbstractObjectiveTo investigate anti‐neurofascin 155 (NF155) antibody‐positive chronic inflammatory demyelinating polyneuropathy (CIDP).MethodsSera from 50 consecutive CIDP patients diagnosed in our clinic, 32 patients with multiple sclerosis, 40 patients with other neuropathies including 26 with Guillain–Barré syndrome (GBS)/Fisher syndrome, and 30 healthy controls were measured for anti‐NF antibodies by flow cytometry using HEK293 cell lines stably expressing human NF155 or NF186. Four additional CIDP patients with anti‐NF155 antibodies referred from other clinics were enrolled for clinical characterization.ResultsThe positivity rate for anti‐NF155 antibodies in CIDP patients was 18% (9/50), who all showed a predominance of IgG4 subclass. No other subjects were positive, except one GBS patient harboring IgG1 anti‐NF155 antibodies. No anti‐NF155 antibody carriers had anti‐NF186 antibodies. Anti‐NF155 antibody‐positive CIDP patients had a significantly younger onset age, higher frequency of drop foot, gait disturbance, tremor and distal acquired demyelinating symmetric phenotype, greater cervical root diameter on magnetic resonance imaging neurography, higher cerebrospinal fluid protein levels, and longer distal and F‐wave latencies than anti‐NF155 antibody‐negative patients. Marked symmetric hypertrophy of cervical and lumbosacral roots/plexuses was present in all anti‐NF155 antibody‐positive CIDP patients examined by neurography. Biopsied sural nerves from two patients with anti‐NF155 antibodies demonstrated subperineurial edema and occasional paranodal demyelination, but no vasculitis, inflammatory cell infiltrates, or onion bulbs. Among anti‐NF155 antibody‐positive patients, treatment responders more frequently had daily oral corticosteroids and/or immunosuppressants in addition to intravenous immunoglobulins than nonresponders did.InterpretationAnti‐NF155 antibodies occur in a subset of CIDP patients with distal‐dominant involvement and symmetric nerve hypertrophy.
Aryl λ3‐Iodane‐Mediated 6‐exo‐trig Cyclization to Synthesize Highly Substituted Chiral Morpholines
Authors: Kishore Vandavasi Jaya , Hu Wan‐Ping , Chandru Senadi Gopal , Chen Hui‐Ting , Chen Hsing‐Yin , Hsieh Kuang‐Chan , Wang Jeh‐Jeng 
Published: September 2015

AbstractA mild and efficient transition metal‐free approach has been developed for the synthesis of highly substituted chiral morpholines from alkenols by amino acid‐derived iodine(III) reagents via a 6‐exo‐trig cyclization. The key features of this work include the formation of three chiral centers with a high diastereomeric ratio, broad functional group compatibility, and atom/time economic methodology.magnified image
Intermolecular versus Intramolecular Palladium‐Catalyzed Direct Arylations between 1‐(2‐Bromobenzyl)imidazoles and Aryl Bromides
Authors: Xu Xiaowen , Zhao Liqin , Li Yiqun , Soulé Jean‐François , Doucet Henri 
Published: September 2015

AbstractHerein, we report on the sequential palladium‐catalyzed intermolecular followed by intramolecular direct arylations of 1‐(2‐bromobenzyl)imidazoles. We found that, in the presence of 1 mol% palladium acetate and potassium acetate as base, the intermolecular reaction between 1‐(2‐bromobenzyl)imidazole derivatives and electron‐deficient aryl bromides proceeded faster than the intramolecular reaction, allowing us to prepare medium‐size polycyclic imidazoles after a second Pd‐catalyzed intramolecular arylation. These iterative direct arylations allowed the synthesis of fused nitrogen‐containing heterocycles with a 5‐ or 7‐membered‐ring in only two steps. Some reactions have also been performed as a one‐pot procedure using 2 mol% of palladium acetate in the presence of a larger amount of base (3 equiv.).magnified image
Enantioselective α‐Alkylation of Benzylideneamino tert‐Butyl Malonates by Phase‐Transfer Catalysis
Authors: Park Cheonhyoung , Ha Min Woo , Kim Byungsoo , Hong Suckchang , Kim Doyoung , Park Yohan , Kim Mi‐hyun , Lee Jae Kyun , Lee Jeeyeon , Park Hyeung‐geun 
Published: September 2015

AbstractA new enantioselective synthetic method for the synthesis of α,α‐dialkylmalonates with a quaternary carbon center was developed via α‐alkylation of prochiral malonates by phase‐transfer catalysis (PTC). Asymmetric α‐alkylation of benzylideneamino tert‐butyl α‐methylmalonates under phase‐transfer catalytic conditions in the presence of (S,S)‐3,4,5‐trifluorophenyl‐NAS bromide afforded the corresponding α,α‐dialkylmalonates in high yields (up to 97%) with excellent enantioselectivities (up to 98% ee). The products were then selectively hydrolyzed to chiral malonic monoacids under basic, acidic, or catalytic hydrogenation conditions.magnified image
Platinum(IV)‐Catalyzed Synthesis of Unsymmetrical Polysubstituted Benzenes via Intramolecular Cycloaromatization Reaction
Authors: Zheng Shuyan , Zhang Jinghua , Shen Zhengwu 
Published: September 2015

AbstractA one‐pot synthesis of polysubstituted benzene derivatives was achieved via a platinum(IV)‐catalyzed intramolecular cycloaromatization reaction. The reaction proceeds via a tandem skeletal rearrangment, dehydration and double bond isomerization, which proved to be very useful for the syntheses of a range of interesting polyalkyl‐substituted benzenes.magnified image
Direct Synthesis of Hemiaminal Ethers via a Three‐Component Reaction of Aldehydes, Amines and Alcohols
Authors: Beltrán Álvaro , Álvarez Eleuterio , Díaz‐Requejo M. Mar , Pérez Pedro J. 
Published: September 2015

AbstractThe reaction of aldehydes, amines and alcohols usually leads to a series of equilibria from which isolation of one product is difficult to achieve. We have found that this three‐component reaction can be controlled and directed in an exclusive manner toward the formation of the hemiaminal ether. A series of 33 hemiaminal ethers has been obtained in high yields, from different aldehydes, amines and alcohols, under very mild conditions just with molecular sieves as promoter.magnified image
Development and In Vitro Evaluation of High Molecular Weight Chitosan Based Polymeric Composites for Controlled Delivery of Valsartan
Authors: SOHAIL MUHAMMAD , AHMAD MAHMOOD , MINHAS MUHAMMAD USMAN , RASHID HAROON , KHALID IKRIMA 
Published: September 2015

ABSTRACTThe purpose of present study was to develop chemically cross‐linked chitosan‐co‐poly(AMPS) hydrogel for pH‐responsive and controlled delivery of valsartan. Hydrogels were synthesized using the free radical polymerization technique. A polymer (high molecular weight chitosan) was chemically cross‐linked with monomer (2‐acrylamido‐2‐methylpropane sulfonic acid (AMPS)) in aqueous medium. NʹNʹ‐Methylenebisacrylamide was used as a cross‐linker. Sodium hydrogen sulfite and ammonium peroxodisulfate were used as initiators. Drug loading was performed with valsartan as a model drug. Characterization of hydrogels was performed by SEM, FTIR, and DSC. Hydrogels were evaluated for pH‐responsive behavior by the equilibrium swelling ratio and swelling dynamics at low and high pH. The developed cross‐linked network showed pH‐dependent drug release characteristics. Maximum swelling, drug loading, and release have been observed at pH 7.4. It is concluded that highly stable chitosan and AMPS‐based polymeric matrices are developed. These polymeric matrices have potential to be used as a carrier for controlled delivery of valsartan.
Generation of Hydrogen from Zero‐Valent Iron and Water: Catalytic Transfer Hydrogenation of Olefins in Presence of Pd/C
Authors: Patil Rajendra D. , Sasson Yoel 
Published: September 2015

AbstractA non‐hazordous and mild protocol was developed for an efficient reduction of alkenes to alkanes using “iron‐activated water” and catalytic Pd/C (2.5 mol %). Water functions as a hydrogen source without any external acid or base and in the absence of another solvent. The Pd/C catalyst was recovered and recycled. In the course of the reaction zero valent iron is oxidized to magnetite.
Photoredox‐Catalyzed Stereoselective Conversion of Alkynes into Tetrasubstituted Trifluoromethylated Alkenes
Authors: Tomita Ren , Koike Takashi , Akita Munetaka 
Published: September 2015

AbstractA regio‐ and stereoselective synthesis of trifluoromethylated alkenes bearing four different substituents has been developed. Stereocontrolled sulfonyloxytrifluoromethylation of unsymmetric internal alkynes with an electrophilic CF3 reagent, namely the triflate salt of the Yagupol’skii–Umemoto reagent, in the presence of an Ir photoredox catalyst under visible‐light irradiation afforded trifluoromethylalkenyl triflates with well‐predictable stereochemistry resulting from anti addition of the trifluoromethyl and triflate groups. Subsequent palladium‐catalyzed cross‐couplings led to tetrasubstituted trifluoromethylated alkenes in a highly stereoselective manner. The present method is the first example of a facile one‐pot synthesis of tetrasubstituted trifluoromethylated alkenes from simple alkynes.
Comparison of dppf‐Supported Nickel Precatalysts for the Suzuki–Miyaura Reaction: The Observation and Activity of Nickel(I)
Authors: Guard Louise M. , Mohadjer Beromi Megan , Brudvig Gary W. , Hazari Nilay , Vinyard David J. 
Published: September 2015

AbstractNi‐based precatalysts for the Suzuki–Miyaura reaction have potential chemical and economic advantages compared to commonly used Pd systems. Here, we compare Ni precatalysts for the Suzuki–Miyaura reaction supported by the dppf ligand in 3 oxidation states, 0, I and II. Surprisingly, at 80 °C they give similar catalytic activity, with all systems generating significant amounts of NiI during the reaction. At room temperature a readily accessible bench‐stable NiII precatalyst is highly active and can couple synthetically important heterocyclic substrates. Our work conclusively establishes that NiI species are relevant in reactions typically proposed to involve exclusively Ni0 and NiII complexes.
Bioorthogonale enzymatische Aktivierung maskierter Verbindungen
Authors: Ritter Cornelia , Nett Nathalie , Acevedo‐Rocha Carlos G. , Lonsdale Richard , Kräling Katja , Dempwolff Felix , Hoebenreich Sabrina , Graumann Peter L. , Reetz Manfred T. , Meggers Eric 
Published: September 2015

AbstractWir berichten über die Verwendung evolvierter Varianten von Cytochrom‐P450‐Monooxygenasen als hochaktive und hochselektive Katalysatoren für die bioorthogonale Aktivierung Propargylether‐ und Benzylether‐maskierter Substrate, einschließlich der erfolgreichen Entschützung in lebenden E. coli. Docking‐Studien und Moleküldynamik‐Simulationen stützen die beobachtete Selektivität. Diese Studie veranschaulicht den möglichen Nutzen von bioorthogonalen Paaren aus Enzym und Schutzgruppe für Anwendungen in den Lebenswissenschaften.
Long‐Range Residual Dipolar Couplings: A Tool for Determining the Configuration of Small Molecules
Authors: Nath Nilamoni , d'Auvergne Edward J. , Griesinger Christian 
Published: September 2015

AbstractTogether with NOE and J coupling, one‐bond residual dipolar coupling (RDC), which reports on the three‐dimensional orientation of an internuclear vector in the molecular frame, plays an important role in the conformation and configuration analysis of small molecules in solution by NMR spectroscopy. When the molecule has few CH bonds, or too many bonds are in parallel, the available RDCs may not be sufficient to obtain the alignment tensor used for structure elucidation. Long‐range RDCs that connect nuclei over multiple bonds are normally not parallel to the single bonds and therefore complement one‐bond RDCs. Herein we present a method for extracting the long‐range RDC of a chosen proton or group of protons to all remotely connected carbon atoms, including non‐protonated carbon atoms. Alignment tensors fitted directly to the total long‐range couplings (T=J+D) enabled straightforward analysis of both the long‐range and one‐bond RDCs for strychnine.
Rational Control of Polyketide Extender Units by Structure‐Based Engineering of a Crotonyl‐CoA Carboxylase/Reductase in Antimycin Biosynthesis
Authors: Zhang Lihan , Mori Takahiro , Zheng Qingfei , Awakawa Takayoshi , Yan Yan , Liu Wen , Abe Ikuro 
Published: September 2015

AbstractBioengineering of natural product biosynthesis is a powerful approach to expand the structural diversity of bioactive molecules. However, in polyketide biosynthesis, the modification of polyketide extender units, which form the carbon skeletons, has remained challenging. Herein, we report the rational control of polyketide extender units by the structure‐based engineering of a crotonyl‐CoA carboxylase/reductase (CCR), in the biosynthesis of antimycin. Site‐directed mutagenesis of the CCR enzyme AntE, guided by the crystal structure solved at 1.5 Å resolution, expanded its substrate scope to afford indolylmethylmalonyl‐CoA by the V350G mutation. The mutant A182L selectively catalyzed carboxylation over the regular reduction. Furthermore, the combinatorial biosynthesis of heterocycle‐ and substituted arene‐bearing antimycins was achieved by an engineered Streptomyces strain bearing AntEV350G. These findings deepen our understanding of the molecular mechanisms of the CCRs, which will serve as versatile biocatalysts for the manipulation of building blocks, and set the stage for the rational design of polyketide biosynthesis.
Silver(I)‐Catalyzed N‐Trifluoroethylation of Anilines and O‐Trifluoroethylation of Amides with 2,2,2‐Trifluorodiazoethane
Authors: Luo Haiqing , Wu Guojiao , Zhang Yan , Wang Jianbo 
Published: September 2015

AbstractA straightforward N‐trifluoroethylation of anilines has been developed based on silver‐catalyzed NH insertions with 2,2,2‐trifluorodiazoethane (CF3CHN2). Mechanistically, the reaction is proposed to involve migratory insertion of a silver carbene as the key step. In contrast, when amides are employed as the substrates under similar reaction conditions, O‐trifluoroethylation occurs to afford trifluoroethyl imidates.
Conformational Analysis, Thermal Rearrangement, and EI‐MS Fragmentation Mechanism of (1(10)E,4E,6S,7R)‐Germacradien‐6‐ol by 13C‐Labeling Experiments
Authors: Rabe Patrick , Barra Lena , Rinkel Jan , Riclea Ramona , Citron Christian A. , Klapschinski Tim A. , Janusko Aron , Dickschat Jeroen S. 
Published: September 2015

AbstractAn uncharacterized terpene cyclase from Streptomyces pratensis was identified as (+)‐(1(10)E,4E,6S,7R)‐germacradien‐6‐ol synthase. The enzyme product exists as two interconvertible conformers, resulting in complex NMR spectra. For the complete assignment of NMR data, all fifteen (13C1)FPP isotopomers (FPP=farnesyl diphosphate) and (13C15)FPP were synthesized and enzymatically converted. The products were analyzed using various NMR techniques, including 13C, 13C COSY experiments. The (13C)FPP isotopomers were also used to investigate the thermal rearrangement and EI fragmentation of the enzyme product.
Aminating modification of viscose fibers and their CO2 adsorption properties
Authors: Wu Qinghua , Chen Shuixia , Luo Shihe , Xu Teng 
Published: September 2015

ABSTRACTAn adsorbent for CO2 capture was prepared by the grafting of acrylonitrile (AN) onto viscose fibers (VFs); this was followed by amination with triethylene tetramine (TETA). The effects of the reaction conditions, such as the concentrations of the monomer, initiator, and nitric acid, on the grafting degree and grafting efficiency were studied. The adsorption performance of the adsorbent for CO2 was evaluated by fixed‐bed adsorption. The highest dynamic adsorption capacity of the adsorbent for CO2 was 4.35 mmol/g when the amine content of the adsorbent VF–AN–TETA reached 13.21 mmol/g. Compared with the polypropylene (PP)‐fiber‐based adsorbent (PP–AN–TETA), VF–AN–TETA with hydroxyl groups on the fibers facilitated the diffusion of CO2 and water and led to a higher CO2 adsorption capacity than that of PP–AN–TETA. The VF–AN–TETA adsorbent also showed good regeneration performance: its CO2 adsorption capacity could still retain almost the same capacity as the fresh adsorbent after 10 adsorption–desorption cycles. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 132, 42840.
Induction of Canonical Wnt Signaling by the Alarmins S100A8/A9 in Murine Knee Joints: Implications for Osteoarthritis
Authors: van den Bosch Martijn H. , Blom Arjen B. , Schelbergen Rik F. P. , Vogl Thomas , Roth Johannes P. , Slöetjes Annet W. , van den Berg Wim B. , van der Kraan Peter M. , van Lent Peter L. E. M. 
Published: September 2015

ObjectiveBoth alarmins S100A8/A9 and canonical Wnt signaling have been found to play active roles in the development of experimental osteoarthritis (OA). However, what activates canonical Wnt signaling remains unknown. This study was undertaken to investigate whether S100A8 induces canonical Wnt signaling and whether S100 proteins exert their effects via activation of Wnt signaling.MethodsExpression of the genes for S100A8/A9 and Wnt signaling pathway members was measured in an experimental OA model. Selected Wnt signaling pathway members were overexpressed, and levels of S100A8/A9 were measured. Activation of canonical Wnt signaling was determined after injection of S100A8 into naive joints and induction of collagenase‐induced OA in S100A9‐deficient mice. Expression of Wnt signaling pathway members was tested in macrophages and fibroblasts after S100A8 stimulation. Canonical Wnt signaling was inhibited in vivo to determine if the effects of S100A8 injections were dependent on Wnt signaling.ResultsThe alarmins S100A8/A9 and members of the Wnt signaling pathway showed coinciding expression in synovial tissue in an experimental OA model. Synovial overexpression of selected Wnt signaling pathway members did not result in increased expression of S100 proteins. In contrast, intraarticular injection of S100A8 increased canonical Wnt signaling, whereas canonical Wnt signaling was decreased after induction of experimental OA in S100A9‐deficient mice. S100A8 stimulation of macrophages, but not fibroblasts, resulted in increased expression of canonical Wnt signaling members. Overexpression of Dkk‐1 to inhibit canonical Wnt signaling decreased the induction of matrix metalloproteinase 3, interleukin‐6, and macrophage inflammatory protein 1α after injection of S100A8.ConclusionOur findings indicate that the alarmin S100A8 induces canonical Wnt signaling in macrophages and murine knee joints. The effects of S100A8 are partially dependent on activation of canonical Wnt signaling.