bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Facile and Efficient Modification of CNTs for Improved Fischer–Tropsch Performance on Iron Catalyst: Alkali Modification
Authors: Liu Renjie , Xu Yan , Li Zhenhua , Ma Xinbin 
Published: January 2016

AbstractIn this paper, a facile and environmentally benign method is used to pretreat carbon nanotubes (CNTs) by alkali modification, which decreases the wall thickness, increases the inner diameter, and improves the graphitization degree of CNTs compared to conventional acid treatment. The iron catalyst supported on alkali modified CNTs shows extraordinary Fischer–Tropsch synthesis (FTS) activity and CO conversion (1.78 and 2.41 times, respectively) compared with those supported on either the acid treated or pristine CNTs. Additionally, the diesel (C10‐20) selectivity on Fe/CNTs‐Na is up to 60 %, which is much higher than that calculated from the Anderson–Schulz–Flory distribution (39 %). Similar results are also found by using activated carbon (AC) and N‐doped multiwall carbon nanotubes (NCNTs) as supports for FTS, proving the universal applicability of alkali modification on carbon material. The positive relationship between the C5+ selectivity and C2−C4 olefin/paraffin ratio of iron catalyst can also be achieved irrespective of the support type.
Activity and Stability of Ruddlesden–Popper‐Type Lan+1NinO3n+1 (n=1, 2, 3, and ∞) Electrocatalysts for Oxygen Reduction and Evolution Reactions in Alkaline Media
Authors: Yu Jie , Sunarso Jaka , Zhu Yinlong , Xu Xiaomin , Ran Ran , Zhou Wei , Shao Zongping 
Published: January 2016

AbstractIncreasing energy demands have stimulated intense research activity on cleaner energy conversion such as regenerative fuel cells and reversible metal–air batteries. It is highly challenging but desirable to develop low‐cost bifunctional catalysts for both the oxygen reduction reaction (ORR) and the oxygen evolution reaction (OER), the lack of which is currently one of the major limiting components towards commercialization of these technologies. Here, we have conducted a systematic study on the OER and ORR performances of the Ruddlesden–Popper family of Lan+1NinO3n+1 (n=1, 2, 3, and ∞) in an alkaline medium for the first time. It is apparent that the Ni−O bond lengths and the hyperstoichiometric oxides in the rock‐salt layers correlate with the ORR activities, whereas the OER activities appear to be influenced by the OH− content on the surface of the compounds. In our case, the electronic configuration fails to predict the electrocatalytic activity of these compounds. This work provides guidelines to develop new electrocatalysts with improved performances.
Unprecedented Spectroscopic and Computational Evidence for Allenyl and Propargyl Titanocene(IV) Complexes: Electrophilic Quenching of Their Metallotropic Equilibrium
Authors: Ruiz‐Muelle Ana Belén , Oña‐Burgos Pascual , Ortuño Manuel A. , Oltra J. Enrique , Rodríguez‐García Ignacio , Fernández Ignacio 
Published: January 2016

AbstractThe synthesis and structural characterization of allenyl titanocene(IV) [TiClCp2(CH=C=CH2)] 3 and propargyl titanocene(IV) [TiClCp2(CH2−C≡C−(CH2)4CH3)] 9 have been described for the first time. Advanced NMR methods including diffusion NMR methods (diffusion pulsed field gradient stimulated spin echo (PFG‐STE) and DOSY) have been applied and established that these organometallics are monomers in THF solution with hydrodynamic radii (from the Stokes–Einstein equation) of 3.5 and 4.1 Å for 3 and 9, respectively. Full 1H, 13C, Δ1H, and Δ13C NMR data are given, and through the analysis of the Ramsey equation, the first electronic insights into these derivatives are provided. In solution, they are involved in their respective metallotropic allenyl–propargyl equilibria that, after quenching experiments with aromatic and aliphatic aldehydes, ketones, and protonating agents, always give the propargyl products P (when carbonyls are employed), or allenyl products A (when a proton source is added) as the major isomers. In all the cases assayed, the ratio of products suggests that the metallotropic equilibrium should be faster than the reactions of 3 and 9 with electrophiles. Indeed, DFT calculations predict lower Gibbs energy barriers for the metallotropic equilibrium, thus confirming dynamic kinetic resolution.
Internalization of Ineffective Platinum Complex in Nanocapsules Renders It Cytotoxic
Authors: Vrana Oldrich , Novohradsky Vojtech , Medrikova Zdenka , Burdikova Jana , Stuchlikova Olga , Kasparkova Jana , Brabec Viktor 
Published: January 2016

AbstractAnticancer therapy by platinum complexes, based on nanocarrier‐based delivery, may offer a new approach to improve the efficacy and tolerability of the platinum family of anticancer drugs. The original rules for the design of new anticancer platinum drugs were affected by the fact that, although cisplatin (cis‐[PtCl2(NH3)2) was an anticancer drug, its isomer transplatin was not cytotoxic. For the first time, it is demonstrated that simple encapsulation of an inactive platinum compound in phospholipid bilayers transforms it into an efficient cytotoxic agent. Notably, the encapsulation of transplatin makes it possible to overcome the resistance mechanisms operating in cancer cells treated with cisplatin and prevents inactivation of transplatin in the extracellular environment. It is also shown that transplatin delivered to the cells in nanocapsules, in contrast to free (nonencapsulated) complex, forms cytotoxic cross‐links on DNA.
Synthesis of Methylene‐Bridged Biscarbazole Alkaloids by using an Ullmann‐type Coupling: First Total Synthesis of Murrastifoline‐C and Murrafoline‐E
Authors: Kutz Sebastian K. , Börger Carsten , Schmidt Arndt W. , Knölker Hans‐Joachim 
Published: January 2016

AbstractWe describe the total synthesis of methylene‐bridged biscarbazole alkaloids by using a late‐stage Ullmann‐type coupling of fully functionalised carbazole subunits. The carbazole derivatives were synthesised via a sequence of palladium(0)‐ and palladium(II)‐catalysed coupling reactions. Our approach has provided bismurrayafoline‐A, bismurrayafolinol, chrestifolines B–D, and the first total synthesis of murrastifoline‐C and murrafoline‐E.
Positive emotions and brain reward circuits in chronic pain
Authors: Navratilova Edita , Morimura Kozo , Xie Jennifer Y. , Atcherley Christopher W. , Ossipov Michael H. , Porreca Frank 
Published: January 2016

ABSTRACTChronic pain is an important public health problem that negatively impacts the quality of life of affected individuals and exacts enormous socioeconomic costs. Chronic pain is often accompanied by comorbid emotional disorders including anxiety, depression, and possibly anhedonia. The neural circuits underlying the intersection of pain and pleasure are not well understood. We summarize recent human and animal investigations and demonstrate that aversive aspects of pain are encoded in brain regions overlapping with areas processing reward and motivation. We highlight findings revealing anatomical and functional alterations of reward/motivation circuits in chronic pain. Finally, we review supporting evidence for the concept that pain relief is rewarding and activates brain reward/motivation circuits. Adaptations in brain reward circuits may be fundamental to the pathology of chronic pain. Knowledge of brain reward processing in the context of pain could lead to the development of new therapeutics for the treatment of emotional aspects of pain and comorbid conditions. J. Comp. Neurol. 524:1646–1652, 2016. © 2016 Wiley Periodicals, Inc.
Light‐Switchable Peptides with a Hemithioindigo Unit: Peptide Design, Photochromism, and Optical Spectroscopy
Authors: Kitzig S. , Thilemann M. , Cordes T. , Rück‐Braun Karola 
Published: January 2016

AbstractThis Minireview focuses on the hemithioindigo photoswitch and its use for the reversible control of three‐dimensional peptide structure and related biological functions. Both the general design aspects and biophysical properties of various hemithioindigo‐based chromopeptides are summarized. Hemithioindigo undergoes reversible Z→E photoisomerization after absorption of visible light. The unique ultrafast switching mechanism of hemithioindigo combines picosecond isomerization kinetics with strong double‐bond torsion after light absorption, making it the ideal tool for instantaneous modulation of biological structure. Various inhibitors and model peptides based on hemithioindigo are described that can directly regulate biological signaling or allow the fastest events in peptide folding to be studied. Finally, a diverse range of chromopeptides with photoswitchable β‐hairpin structures based on azobenzenes, stilbenes, and hemithioindigo are compared to emphasize the unique properties of hemithioindigo.
Ultrafast Electron Transfer in Complexes of Doxorubicin with Human Telomeric G‐Quadruplexes and GC Duplexes Probed by Femtosecond Fluorescence Spectroscopy
Authors: Changenet‐Barret Pascale , Gustavsson Thomas , Markovitsi Dimitra , Manet Ilse 
Published: January 2016

AbstractDoxorubicin (DOX) is a natural anthracycline widely used in chemotherapy; its combined application as a chemotherapeutic and photodynamic agent has been recently proposed. In this context, understanding the photoinduced properties of DOX complexes with nucleic acids is crucial. Herein, the study of photoinduced electron transfer in DOX–DNA complexes by femtosecond fluorescence spectroscopy is reported. The behaviour of complexes with two model DNA structures, a G‐quadruplex (G4) formed by the human telomeric sequence (Tel21) and a d(GC) duplex, is compared. The DOX affinity for these two sequences is similar. Although both 1:1 and 2:1 stoichiometries have been reported for DOX–G4 complexes, only 1:1 complexes form with the duplex. The steady‐state absorption indicates a strong binding interaction with the duplex due to drug intercalation between the GC base pairs. In contrast, the interaction of DOX with Tel21 is much weaker and arises from drug binding on the G4 external faces at two independent binding sites. As observed for DOX–d(GC) complexes, fluorescence of the drug in the first binding site of Tel21 exhibits decays within a few picoseconds following a biphasic pattern; this is attributed to the existence of two drug conformations. The fluorescence of the drug in the second binding site of Tel21 shows slower decays within 150 ps. These timescales are consistent with electron transfer from the guanines to the excited drug, as favoured by the lower oxidation potential of the stacked guanines of G4 with respect to those in the duplex.
Molecular Design Guidelines for Large Magnetic Circular Dichroism Intensities in Lanthanide Complexes
Authors: Kitagawa Yuichi , Wada Satoshi , Yanagisawa Kei , Nakanishi Takayuki , Fushimi Koji , Hasegawa Yasuchika 
Published: January 2016

AbstractMagneto optical devices based on the Faraday effects of lanthanide ion have attracted much attention. Recently, large Faraday effects were found in nano‐sized multinuclear lanthanide complexes. In this study, the Faraday rotation intensities were estimated for lanthanide nitrates [LnIII(NO3)3⋅n H2O: Ln=Pr, Nd, Sm, Eu, Tb, Dy, Ho, Er, Tm) and EuIII complexes with β‐diketone ligands, using magnetic circular dichroism. Eu ions exhibit the largest Faraday rotation intensity for 7F0→5D1 transitions, and high‐symmetry fields around the Eu ions induce larger Faraday effects. The molecular design for the enhancement of Faraday effects in lanthanide complexes is discussed.
Ab Initio and DFT Studies on CO2 Interacting with Znq+–Imidazole (q=0, 1, 2) Complexes: Prediction of Charge Transfer through σ‐ or π‐Type Models
Authors: Boulmene Reda , Boussouf Karim , Prakash Muthuramalingam , Komiha Najia , Al‐Mogren Muneerah M. , Hochlaf Majdi 
Published: January 2016

AbstractUsing first‐principles methodologies, the equilibrium structures and the relative stability of CO2@[Znq+Im] (where q=0, 1, 2; Im=imidazole) complexes are studied to understand the nature of the interactions between the CO2 and Znq+–imidazole entities. These complexes are considered as prototype models mimicking the interactions of CO2 with these subunits of zeolitic imidazolate frameworks or Zn enzymes. These computations are performed using both ab initio calculations and density functional theory. Dispersion effects accounting for long‐range interactions are considered. Solvent (water) effects were also considered using a polarizable continuum model approach. Natural bond orbital, charge, frontier orbital and vibrational analyses clearly reveal the occurrence of charge transfer through covalent and noncovalent interactions. Moreover, it is found that CO2 can adsorb through more favorable π‐type stacking as well as σ‐type hydrogen‐bonding interactions. The inter‐monomer interaction potentials show a significant anisotropy that might induce CO2 orientation and site‐selectivity effects in porous materials and in active sites of Zn enzymes. Hence, this study provides valuable information about how CO2 adsorption takes place at the microscopic level within zeolitic imidazolate frameworks and biomolecules. These findings might help in understanding the role of such complexes in chemistry, biology and material science for further development of new materials and industrial applications.
Constraints on barium isotope fractionation during aragonite precipitation by corals
Authors: Pretet Chloé , van Zuilen Kirsten , Nägler Thomas F. , Reynaud Stéphanie , Böttcher Michael E. , Samankassou Elias 
Published: January 2016

AbstractWe present a barium (Ba) isotope fractionation study of marine biogenic carbonates (aragonitic corals). The major aim is to provide first constraints on the Ba isotope fractionation between modern surface seawater and coral skeleton. Mediterranean surface seawater was found to be enriched in the heavy Ba isotopes compared to previously reported values for marine open ocean authigenic and terrestrial minerals. In aquarium experiments with a continuous supply of Mediterranean surface water, the Ba isotopic composition of the bulk sample originating from cultured, aragonitic scleractinian corals (δ137/134Ba between +0·16 ± 0·12‰ and +0·41 ± 0·12‰) were isotopically identical or lighter than that of the ambient Mediterranean surface seawater (δ137/134Ba = +0·42 ± 0·07‰, 2SD), which corresponds to an empirical maximum value of Ba isotope fractionation of Δ137/134Bacoral‐seawater = −0·26 ± 0·14‰ at 25°C. This maximum Ba isotope fractionation is close and identical in direction to previous results from inorganic precipitation experiments with aragonite‐structured pure BaCO3 (witherite). The variability in measured Ba concentrations of the cultured corals is at odds with a uniform distribution coefficient, D(Ba/Ca), thus indicating stronger vital effects on isotope than element discrimination. This observation supports the hypothesis that the Ba isotopic compositions of these corals do not result from simple equilibrium between the skeleton and the bulk seawater. Complementary coral samples from natural settings (tropical shallow‐water corals from the Bahamas and Florida and cold‐water corals from the Norwegian continental shelf) show an even wider range in δ137/134Ba values (+0·14 ± 0·08 to +0·77 ± 0·11‰), most probably due to additional spatial and/or temporal seawater heterogeneity, as indicated by recent publications.
Treatment intensification in patients with inadequate glycemic control on basal insulin: rationale and clinical evidence for the use of short‐acting and other glucagon‐like peptide‐1 receptor agonists
Authors: Giorgino Francesco , Bonadonna Riccardo C. , Gentile Sandro , Vettor Roberto , Pozzilli Paolo 
Published: January 2016

SummaryA substantial proportion of patients with type 2 diabetes mellitus do not reach glycemic targets, despite treatment with oral anti‐diabetic drugs and basal insulin therapy. Several options exist for treatment intensification beyond basal insulin, and the treatment paradigm is complex. In this review, the options for treatment intensification will be explored, focusing on drug classes that act via the incretin system and paying particular attention to the short‐acting glucagon‐like peptide‐1 receptor agonists exenatide and lixisenatide. Current treatment guidelines will be summarized and discussed. © 2016 The Authors. Diabetes/Metabolism Research and Reviews Published by John Wiley & Sons Ltd.
Nrl‐Cre transgenic mouse mediates loxP recombination in developing rod photoreceptors
Authors: Brightman Diana S. , Razafsky David , Potter Chloe , Hodzic Didier , Chen Shiming 
Published: January 2016

SummaryThe developing mouse retina is a tractable model for studying neurogenesis and differentiation. Although transgenic Cre mouse lines exist to mediate conditional genetic manipulations in developing mouse retinas, none of them act specifically in early developing rods. For conditional genetic manipulations of developing retinas, a Nrl‐Cre mouse line in which the Nrl promoter drives expression of Cre in rod precursors was created. The results showed that Nrl‐Cre expression was specific to the retina where it drives rod‐specific recombination with a temporal pattern similar to endogenous Nrl expression during retinal development. This Nrl‐Cre transgene does not negatively impact retinal structure and function. Taken together, the data suggested that the Nrl‐Cre mouse line was a valuable tool to drive Cre‐mediated recombination specifically in developing rods. genesis 54:129–135, 2016. © 2016 Wiley Periodicals, Inc.
Fine root tradeoffs between nitrogen concentration and xylem vessel traits preclude unified whole‐plant resource strategies in Helianthus
Authors: Bowsher Alan W. , Mason Chase M. , Goolsby Eric W. , Donovan Lisa A. 
Published: January 2016

AbstractRecent work suggests variation in plant growth strategies is governed by a tradeoff in resource acquisition and use, ranging from a rapid resource acquisition strategy to a resource‐conservative strategy. While evidence for this tradeoff has been found in leaves, knowledge of root trait strategies, and whether they reflect adaptive differentiation across environments, is limited. In the greenhouse, we investigated variation in fine root morphology (specific root length and tissue density), chemistry (nitrogen concentration and carbon:nitrogen), and anatomy (root cross‐sectional traits) in populations of 26 Helianthus species and sister Phoebanthus tenuifolius. We also compared root trait variation in this study with leaf trait variation previously reported in a parallel study of these populations. Root traits varied widely and exhibited little phylogenetic signal, suggesting high evolutionary lability. Specific root length and root tissue density were weakly negatively correlated, but neither was associated with root nitrogen, providing little support for a single axis of root trait covariation. Correlations between traits measured in the greenhouse and native site characteristics were generally weak, suggesting a variety of equally viable root trait combinations exist within and across environments. However, high root nitrogen was associated with lower xylem vessel number and cross‐sectional area, suggesting a tradeoff between nutrient investment and water transport capacity. This led to correlations between root and leaf traits that were not always consistent with an acquisition–conservation tradeoff at the whole‐plant level. Given that roots must balance acquisition of water and nutrients with functions like anchorage, exudation, and microbial symbioses, the varied evidence for root trait covariation likely reflects the complexity of interacting selection pressures belowground. Similarly, the lack of evidence for a single acquisition–conservation tradeoff at the whole‐plant level likely reflects the vastly different selection pressures shaping roots and leaves, and the resources they are optimized to obtain.
Occurrence, determination, and assessment of mineral oils in oilseeds and vegetable oils
Authors: Brühl Ludger 
Published: January 2016

Mineral oil hydrocarbon contaminations can often be found in oilseeds, oils, and fats as these matrices are good keepers to accumulate them from all kind of sources along the production chain. In addition, seeds and vegetable oils contain naturally occurring hydrocarbons in various compositions. These naturally hydrocarbons can serve for a proof of authentication and they have to be taken into account for the analysis of mineral oil hydrocarbons as contaminants. In this review, the many sources of contamination like environmental effects, production machinery, and packaging materials are referred to and reported data for contaminated vegetable oils like sunflower, olive, and palm oil and in addition raw materials and feed are focused on. This is of special importance for the food survey and for the production as it is a challenging task to survey the many routes of contamination along the production chain and during storage in order to improve the food quality. There is still discussion where to fix a reasonable limit for such contaminants in oils and fats, where levels are often very high compared to levels found for migration from packaging materials into low fat products. For the later ones draft limits have been discussed, but it will be a challenge to reduce mineral oil hydrocarbon contamination in oils and fats to a similar extend. In addition, the determination of low levels of hydrocarbon contamination is demanding and validation of sophisticated coupled LC–GC methods in collaborative trials is still in development.Practical applications: An overview about the analysis of mineral oil hydrocarbon contaminations of oilseeds, oils, and fats is given. For seeds and vegetable oils also contain naturally occurring hydrocarbons in various compositions, reference data on these naturally hydrocarbons are provided. The many sources of contamination like environmental effects, production machinery, and packaging materials are referred to and vegetable oils like sunflower, olive, and palm oil and in addition raw materials and feed are focused on. The arguments for a reasonable limit for such contaminants in oils and fats are discussed.Analysis of mineral oil hydrocarbon contamination of oilseeds, oils, and fats is reviewed. Reference data on naturally hydrocarbons are provided, which occur in various compositions. The many sources of contamination like environmental effects, production machinery, and packaging materials are referred to and vegetable oils like sunflower, olive, palm oil, raw materials, and feed are focused on. The arguments for a reasonable limit for such contaminants in oils and fats are discussed.
Organic Functionalized Carbon Nanostructures for Functional Polymer‐Based Nanocomposites
Authors: Gatti Teresa , Vicentini Nicola , Mba Miriam , Menna Enzo 
Published: January 2016

AbstractCarbon nanostructures (CNSs), which are made up of extended sp2‐hybridized carbon networks, are largely employed as nanofillers for polymer phases to obtain polymer‐based nanocomposites (PNCs). Following their inclusion, the polymer matrices are often improved in many ways, such as enhanced electrical and thermal conductivity, increased stability, and mechanical robustness. The chemical functionalization of the external CNS surfaces with organic substituents is often a key tool for their effective and homogeneous incorporation within a polymer phase, avoiding the formation of aggregates, which can lower the performance of the the final material. This microreview furnishes an overview of PNCs that contain substituted CNSs with organic functionalities. These CNS‐based PNCs can be used as organic functional materials in different applications that range from clean energy harvesting and storage to sensing and biomedicine.