bluuebunny/crossref_metadata_2025_split huggingface dataset:
Long‐term fertilization alters the relative importance of nitrate reduction pathways in salt marsh sediments
Authors: Peng Xuefeng , Ji Qixing , Angell John H. , Kearns Patrick J. , Yang Hannah J. , Bowen Jennifer L. , Ward Bess B. 
Published: July 2016

AbstractSalt marshes provide numerous valuable ecological services. In particular, nitrogen (N) removal in salt marsh sediments alleviates N loading to the coastal ocean. N removal reduces the threat of eutrophication caused by increased N inputs from anthropogenic sources. It is unclear, however, whether chronic nutrient overenrichment alters the capacity of salt marshes to remove anthropogenic N. To assess the effect of nutrient enrichment on N cycling in salt marsh sediments, we examined important N cycle pathways in experimental fertilization plots in a New England salt marsh. We determined rates of nitrification, denitrification, and dissimilatory nitrate reduction to ammonium (DNRA) using sediment slurry incubations with 15N labeled ammonium or nitrate tracers under oxic headspace (20% oxygen/80% helium). Nitrification and denitrification rates were more than tenfold higher in fertilized plots compared to control plots. By contrast, DNRA, which retains N in the system, was high in control plots but not detected in fertilized plots. The relative contribution of DNRA to total nitrate reduction largely depends on the carbon/nitrate ratio in the sediment. These results suggest that long‐term fertilization shifts N cycling in salt marsh sediments from predominantly retention to removal.
Overcoming the Limitations of C−H Activation with Strongly Coordinating N‐Heterocycles by Cobalt Catalysis
Authors: Wang Hui , Lorion Mélanie M. , Ackermann Lutz 
Published: July 2016

AbstractStrongly coordinating nitrogen heterocycles, including pyrimidines, oxazolines, pyrazoles, and pyridines, were fully tolerated in cobalt‐catalyzed C−H amidations by imidate assistance. Structurally complex quinazolines are thus accessible in a step‐economic manner. Our findings also establish the relative powers of directing groups in cobalt(III)‐catalyzed C−H functionalization for the first time.
Unraveling the Catalytic Synergy between Ti3+ and Al3+ Sites on a Chlorinated Al2O3: A Tandem Approach to Branched Polyethylene
Authors: Piovano Alessandro , Thushara K. S. , Morra Elena , Chiesa Mario , Groppo Elena 
Published: July 2016

AbstractAn original step‐by‐step approach to synthesize and characterize a bifunctional heterogeneous catalyst consisting of isolated Ti3+ centers and strong Lewis acid Al3+ sites on the surface of a chlorinated alumina has been devised. A wide range of physicochemical and spectroscopic techniques were employed to demonstrate that the two sites, in close proximity, act in a concerted fashion to synergistically boost the conversion of ethylene into branched polyethylene, using ethylene as the only feed and without any activator. The coordinatively unsaturated Al3+ ions promote ethylene oligomerization through a carbocationic mechanism and activate the Ti3+ sites for the traditional ethylene coordination polymerization.
Design and Synthesis of a Water‐Stable Anionic Uranium‐Based Metal–Organic Framework (MOF) with Ultra Large Pores
Authors: Li Peng , Vermeulen Nicolaas A. , Gong Xirui , Malliakas Christos D. , Stoddart J. Fraser , Hupp Joseph T. , Farha Omar K. 
Published: July 2016

AbstractIonic metal–organic frameworks (MOFs) are a subclass of porous materials that have the ability to incorporate different charged species in confined nanospace by ion‐exchange. To date, however, very few examples combining mesoporosity and water stability have been realized in ionic MOF chemistry. Herein, we report the rational design and synthesis of a water‐stable anionic mesoporous MOF based on uranium and featuring tbo‐type topology. The resulting tbo MOF exhibits exceptionally large open cavities (3.9 nm) exceeding those of all known anionic MOFs. By supercritical CO2 activation, a record‐high Brunauer‐Emmett‐Teller (BET) surface area (2100 m2 g−1) for actinide‐based MOFs has been obtained. Most importantly, however, this new uranium‐based MOF is water‐stable and able to absorb positively charged ions selectively over negatively charged ones, enabling the efficient separation of organic dyes and biomolecules.
Medium‐Ring Nitrogen Heterocycles through Migratory Ring Expansion of Metalated Ureas
Authors: Hall Jessica E. , Matlock Johnathan V. , Ward John W. , Gray Katharine V. , Clayden Jonathan 
Published: July 2016

AbstractSimple benzo‐fused nitrogen heterocycles (indolines, tetrahydroquinolines, and their homologues) undergo migratory ring expansion through deprotonation of their benzylic urea derivatives with lithium diisopropylamide (LDA) in the presence of N,N′‐dimethylpropylideneurea (DMPU). The products of the reactions are benzodiazepines, benzodiazocines, and their homologues, with ring sizes of 8–12. The reactions tolerate a range of substituent patterns and types, and may exhibit enantiospecificity or diastereoselectivity. Considerable complexity is rapidly generated in an efficient synthesis of these otherwise difficult‐to‐obtain medium‐ring nitrogen heterocycles.
Tuning Pore Size in Square‐Lattice Coordination Networks for Size‐Selective Sieving of CO2
Authors: Chen Kai‐Jie , Madden David G. , Pham Tony , Forrest Katherine A. , Kumar Amrit , Yang Qing‐Yuan , Xue Wei , Space Brian , Perry John J. , Zhang Jie‐Peng , Chen Xiao‐Ming , Zaworotko Michael J. 
Published: July 2016

AbstractPorous materials capable of selectively capturing CO2 from flue‐gases or natural gas are of interest in terms of rising atmospheric CO2 levels and methane purification. Size‐exclusive sieving of CO2 over CH4 and N2 has rarely been achieved. Herein we show that a crystal engineering approach to tuning of pore‐size in a coordination network, [Cu(quinoline‐5‐carboxyate)2]n (Qc‐5‐Cu) ena+bles ultra‐high selectivity for CO2 over N2 (SCN≈40 000) and CH4 (SCM≈3300). Qc‐5‐Cu‐sql‐β, a narrow pore polymorph of the square lattice (sql) coordination network Qc‐5‐Cu‐sql‐α, adsorbs CO2 while excluding both CH4 and N2. Experimental measurements and molecular modeling validate and explain the performance. Qc‐5‐Cu‐sql‐β is stable to moisture and its separation performance is unaffected by humidity.
Simplest Monodentate Imidazole Stabilization of the oxy‐Tyrosinase Cu2O2 Core: Phenolate Hydroxylation through a CuIII Intermediate
Authors: Chiang Linus , Keown William , Citek Cooper , Wasinger Erik C. , Stack T. Daniel P. 
Published: July 2016

AbstractTyrosinases are ubiquitous binuclear copper enzymes that oxygenate to CuII2O2 cores bonded by three histidine Nτ‐imidazoles per Cu center. Synthetic monodentate imidazole‐bonded CuII2O2 species self‐assemble in a near quantitative manner at −125 °C, but Nπ‐ligation has been required. Herein, we disclose the syntheses and reactivity of three Nτ‐imidazole bonded CuII2O2 species at solution temperatures of −145 °C, which was achieved using a eutectic mixture of THF and 2‐MeTHF. The addition of anionic phenolates affords a CuIII2O2 species, where the bonded phenolates hydroxylate to catecholates in high yields. Similar CuIII2O2 intermediates are not observed using Nπ‐bonded CuII2O2 species, hinting that Nτ‐imidazole ligation, conserved in all characterized Ty, has functional advantage beyond active‐site flexibility. Substrate accessibility to the oxygenated Cu2O2 core and stabilization of a high oxidation state of the copper centers are suggested from these minimalistic models.
Effect of using polymeric materials in ecological sand‐fixing of Kerqin Sandy Land of China
Authors: Gong Wei , Zang Yunxiao , Liu Bailing , Chen Hualin , Wu Fusheng , Huang Ronghai , Wang Shaokun 
Published: July 2016

ABSTRACTFor the first time, the main characteristics of the polymeric materials are considered for understanding their possible application in ecological sand‐fixing. In this investigation, two emulsions, named as E2, a poly(vinyl acetate) emulsion, and E7, a vinyl acetate–ethylene copolymer emulsion, have been selected for a series of tests related to the practical requirements for ecological sand‐fixing. Besides the sand‐fixing properties and the thermal aging and freeze–thaw stabilities of the emulsions, their effects in increasing the growth of both microbes and plants in sandy lands have been evaluated by field experiments in Kerqin Sandy Land of China, and the relationship between the performance and structure of the two emulsions has also been described. The experimental results show that both emulsions could significantly improve the compressive strength of treated sand and could withstand the changes in temperature of the Kerqin Sandy Land. However, different effects were exhibited in promoting the growth of microbes, in facilitating the accumulation of organic fertilizer and soluble salt, and in increasing the crop yield. All of the differences are attributed to their different molecular chain structures. These findings suggest that the structure of a polymeric emulsion should be the first consideration for the materials used in ecological sand‐fixing, and ecological sand‐fixing is a successful method for the stabilization of sandy land and the restoration of desertified land in semiarid regions. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci.2016,133, 44102
A structural study of epoxidized natural rubber (ENR‐50) ring opening under mild acidic condition
Authors: Hamzah Rosniza , Bakar Mohamad Abu , Dahham Omar Sabbar , Zulkepli Nik Noriman , Dahham Saad Sabbar 
Published: July 2016

ABSTRACTA structural study of ring opening reaction of purified epoxidized natural rubber (ENR) with acetic acid was conducted using the NMR techniques and its thermal characteristic was evaluated with Thermal gravimetry/Differential Thermal Gravimetry (TG/DTG) and Differential Scanning Calorimetry (DSC) analyses. 1H‐NMR revealed that 19.56% of epoxide was ring‐opened from the total amount of the epoxide unit in ENR‐50 and this was supported by Fourier Transform Infrared (FTIR) spectroscopy. 13C‐NMR suggests the fixation of alkyl (R) i.e., acetate group to the epoxide carbon via ester linkage and formation of hydroxyl groups in the polymer chains. The attachment location of R occurred at both most (↑) and least (↓) hindered carbons of the epoxide. The TG/DTG results of acid treated ENR‐50 showed three decomposition steps at 235–338, 338–523, 523–627 °C due to the presence of the polymer chains mixture, i.e., ring‐opened and intact epoxide of ENR‐50. This increases the Tg value of acid treated ENR‐50 at 24.6 °C as compared to purified ENR‐50 at −17.7 °C. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 44123.
Shape memory crosslinked polyurethanes containing thermoreversible Diels‐Alder couplings
Authors: Lakatos Csilla , Czifrák Katalin , Karger‐Kocsis József , Daróczi Lajos , Zsuga Miklós , Kéki Sándor 
Published: July 2016

ABSTRACTCrosslinked polyurethanes (PUs) containing irreversible (allophanate) and reversible Diels‐Alder chemical bonds were synthesized using various diisocyanates (methylene diphenyl diisocyanate MDI, 1,6‐hexamethylenediisocyanate HDI) and poly(ɛ‐caprolactone) ((PCL) with different molecular weights (Mn = 10 kg/mol, 25 kg/mol, 50 kg/mol) as diol component. The melting/crystallization of PCL and the reversible DA bonds acted as temperature‐activated switches for shape memory performances, while allophanate network provided the permanent crosslinks for these PUs. The reversible DA bonds were obtained by the reaction of diisocyanate‐ended prepolymers with furfurylamine (FA) followed by the addition of bismaleimide (BMI). The permanent crosslinks between the linear chains containing DA bonds were achieved using additional amounts of diisocyanates (MDI or HDI). The above reaction path was supported by infrared spectroscopic results and swelling experiments. Tensile mechanical and shape memory properties in tension of the PUs were determined and discussed as a function of composition and crosslink densities deduced from swelling and dynamic mechanical analysis. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 44145.
Interaction of silylated superplasticizers with cementitious materials
Authors: Lu Zichen , Kong Xiangming , Liu Hui , Wang Ziming , Zhang Yanrong , Dong Biqin , Xing Feng 
Published: July 2016

ABSTRACTIncorporation of silane groups into polycarboxylate superplasticizer (PCE) opens a new technical approach to improve properties of PCE, such as to enhance the adsorption of PCE on cement and hence the dispersing performance, to minimize the retardation effect, and potentially to increase mechanical strength of cement mortars. Silylated PCEs were synthesized using silane monomer via radical copolymerization. Dispersing effect, adsorption behaviors, and influences on mortar strength of these polymers were systematically investigated. Results show that increasing the incorporation of sliane groups in PCE promotes the adsorption of polymer on cement surface and hence leads to good fluidity retention capability. Furthermore, sulfate resistance ability of silylated PCE is superior due to stronger chemical adsorption of polymer on cement surface. The retardation effect of PCE is minimized by the introduction of silane groups. The addition of silylated PCE significantly increases 3 days compressive strength without notably affecting the long‐term strength. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 44161.
Engineering the Interconnecting Position of Star‐Shaped Donor–π–Acceptor Molecules Based on Triazine, Spirofluorene, and Triphenylamine Moieties for Color Tuning from Deep Blue to Green
Authors: Wang Yafei , Liu Wanhui , Deng Jiyong , Xie Guohua , Liao Yuanwei , Qu Zuoming , Tan Hua , Liu Yu , Zhu Weiguo 
Published: July 2016

AbstractPi‐conjugated organic molecules featuring the donor–bridge–acceptor (D–π–A) structure have been widely used in semiconducting materials owing to their rigid structure, good thermal stability, excellent charge transfer, and high emission efficiency. To investigate the effect of the D–π–A molecular structure on the photophysical properties, in this contribution, three star‐shaped D–π–A isomers based on the 2,4,6‐triphenyl‐1,3,5‐triazine, spirofluorene, and triphenylamine moieties, that is, p‐TFTPA, mp‐TFTPA, and m‐TFTPA, were synthesized by elaborately engineering the interconnecting position in the building‐block units. The optophysical properties of these compounds were systematically explored by experiments and theory calculations. Definitively, changing the interconnecting position in these molecules played a significant role in the degree of π conjugation, which resulted in tunable emission colors from deep blue to green. Moreover, these isomers were employed as emissive dopants in organic light‐emitting diodes. The highest external quantum efficiency of 2.3 % and current efficiency of 6.2 cd A−1 were achieved by using the p‐TFTPA based device. This research demonstrates a feasible way to realize blue emitters by engineering D–π–A conjugation.
Protein‐stabilizing and cell‐penetrating properties of α‐helix domain of 30Kc19 protein
Authors: Ryu Jina , Kim Hyoju , Park Hee Ho , Lee Hong Jai , Park Ju Hyun , Rhee Won Jong , Park Tai Hyun 
Published: July 2016

AbstractThe protein‐stabilizing and cell‐penetrating activities of Bombyx mori 30Kc19 α‐helix domain (30Kc19α) are investigated. Recently, 30Kc19 protein has been studied extensively as it has both protein‐stabilizing and cell‐penetrating properties. However, it is unknown which part of 30Kc19 is responsible for those properties. 30Kc19 protein is composed of two distinct domains, an α‐helix N‐terminal domain (30Kc19α) and a β‐trefoil C‐terminal domain (30Kc19β). The authors construct and produce truncated forms of 30Kc19 to demonstrate their biological functions. Interestingly, 30Kc19α was shown to be responsible for both the protein‐stabilizing and cell‐penetrating properties of 30Kc19 protein. 30Kc19α shows even higher protein delivery activity than did whole 30Kc19 protein and has low cytotoxicity when added to cell culture medium. Therefore, based on its multifunctional properties, 30Kc19α can be developed as a novel candidate for a therapeutic protein carrier into various cells and tissues.
Depressive symptoms associated with concerns about falling in Parkinson's disease
Authors: Franzén Erika , Conradsson David , Hagströmer Maria , Nilsson Maria H. 
Published: July 2016

AbstractBackgroundConcerns about falling, a construct related to fear of falling, is increased in people with Parkinson's disease (PD) and is recognized as a barrier for exercise, negatively affecting health‐related quality of life and participation.AimTo investigate modifiable factors associated with concerns about falling in elderly with mild‐to‐moderate PD.MethodsEighty‐nine elderly (39 females, mean age 73 years) with mild‐to‐moderate PD were recruited. Concerns about falling were assessed with the Falls Efficacy Scale‐international, that is, the dependent variable in multiple linear regression analysis. Independent variables included both motor (e.g., objective measures of physical activity and gait) and nonmotor aspects such as depressive symptoms.ResultsA model with three significant independent variables explained 33% of the variance in concerns about falling. According to the standardized regression coefficients (β), the strongest contributing factor was depressive symptoms (0.40), followed by balance performance (−0.25), and use of mobility devices (0.24).ConclusionsThe findings imply that factors associated with concerns about falling are a multifactorial phenomenon. For its management in elderly with mild‐to‐moderate PD, one should consider depressive symptoms, balance deficits, and mobility devices.
Perceived risk: an experimental investigation of consumer behavior when buying wine
Authors: Outreville J. François , Desrochers Jean 
Published: July 2016

AbstractThe purpose of this paper is to investigate differences in expressed attitude as a function of the manner in which information on perceived risk is communicated. The experiments are conducted through a choice‐based questionnaire to reflect the consumer‐oriented decision of the purchase of a bottle of wine based on posted prices. The experiments reported in this paper are based on questionnaires distributed to 323 participants in multiple samples and examine the behavior of people when faced with different information on the probability of loss. The present study demonstrates that changes in the manner in which information is presented, without any underlying change in problem structure, affects observed preferences when buying wine. The impact of perceived risk and character on the willingness to buy and to pay for a bottle is analyzed and show that price habits and perceived risk are the main factors affecting the willingness to pay for a bottle of wine. Copyright © 2016 John Wiley & Sons, Ltd.
An Iterative O‐Methyltransferase Catalyzes 1,11‐Dimethylation of Aspergillus fumigatus Fumaric Acid Amides
Authors: Kalb Daniel , Heinekamp Thorsten , Schieferdecker Sebastian , Nett Markus , Brakhage Axel A. , Hoffmeister Dirk 
Published: July 2016

AbstractS‐adenosyl‐l‐methionine (SAM)‐dependent methyltransfer is a common biosynthetic strategy to modify natural products. We investigated the previously uncharacterized Aspergillus fumigatus methyltransferase FtpM, which is encoded next to the bimodular fumaric acid amide synthetase FtpA. Structure elucidation of two new A. fumigatus natural products, the 1,11‐dimethyl esters of fumaryl‐l‐tyrosine and fumaryl‐l‐phenylalanine, together with ftpM gene disruption suggested that FtpM catalyzes iterative methylation. Final evidence that a single enzyme repeatedly acts on fumaric acid amides came from an in vitro biochemical investigation with recombinantly produced FtpM. Size‐exclusion chromatography indicated that this methyltransferase is active as a dimer. As ftpA and ftpM homologues are found clustered in other fungi, we expect our work will help to identify and annotate natural product biosynthesis genes in various species.
Conjugation and Evaluation of Triazole‐Linked Single Guide RNA for CRISPR‐Cas9 Gene Editing
Authors: He Kaizhang , Chou Eldon T. , Begay Shawn , Anderson Emily M. , van Brabant Smith Anja 
Published: July 2016

AbstractThe CRISPR‐Cas9 gene editing system requires Cas9 endonuclease and guide RNAs (either the natural dual RNA consisting of crRNA and tracrRNA or a chimeric single guide RNA) that direct site‐specific double‐stranded DNA cleavage. This communication describes a click ligation approach that uses alkyne–azide cycloaddition to generate a triazole‐linked single guide RNA (sgRNA). The conjugated sgRNA shows efficient and comparable genome editing activity to natural dual RNA and unmodified sgRNA constructs.
Suppression of Deactivation Processes in Photocatalytic Reduction of CO2 Using Pulsed Light
Authors: Pschenitza Markus , Meister Simon , von Weber Alexander , Kartouzian Aras , Heiz Ueli , Rieger Bernhard 
Published: July 2016

AbstractThe one‐electron‐reduced (OER) species of rhenium‐based catalysts in the homogeneous photocatalytic reduction of CO2 represents the starting point of light‐induced deactivation processes, which lead to low catalyst activity and productivity. Herein, we report the suppression of these processes using pulsed light. Experimental parameters to avoid the irradiation of the OER species were estimated, leading us to conclude that pulse lengths shorter than 1 ns and repetition rates lower than 33 Hz should be employed. [Re(bpy)(CO)3X] (bpy=2,2′‐bipyridine; X=Cl (1), Br (3)) catalysts were employed in pulsed irradiation experiments using different light sources, pulse lengths and repetition rates. Pulsed irradiation experiments using LEDs revealed that a minimum average photon flux is necessary to enable CO2 conversion. Furthermore, pulsed laser light with a 10 ns pulse length partially prevented lightinduced deactivation processes, whereas efficient suppression was achieved using a 30 ps pulse length.
Analysis of Three‐Phase Catalytic Fuel Synthesis Reactors for Flexible Operation
Authors: Eilers Hilko , Schaub Georg 
Published: July 2016

AbstractIn future energy systems, flexible reactor operation may be needed if electricity produced from renewable sources is to be converted into chemical energy carriers (synfuels). Factors limiting the flexibility in a synfuel process can occur on different scales (catalyst, reactor, process). The present study addresses transient catalyst and reactor effects in three‐phase catalytic synthesis reactors with low‐temperature Fischer‐Tropsch synthesis as an example reaction. A method was developed based on lab‐scale experiments with step changes and periodic changes of inlet variables and mathematical models for experimental design and data analysis. Changes of inlet variables such as the feed‐gas flow, syngas H2/CO ratio, and temperature led, in some cases, to transient effects caused by catalyst changes or by reactor characteristics.