bluuebunny/crossref_metadata_2025_split huggingface dataset:
Heavy Metal with a Heavy Impact: Olefin Dimerization Reactions in Triphenylbismuth Buffered Chloroaluminate Ionic Liquids
Authors: Dötterl Matthias , Alt Helmut G. 
Published: September 2011

AbstractThe addition of weak Lewis bases such as NPh3, PPh3, or BiPh3 (Ph=phenyl) to Lewis acidic chloroaluminate ionic liquids yielded efficient cocatalysts for nickel catalyst precursors in highly selective biphasic dimerization reactions of α‐olefins. Triphenylbismuth buffered systems were found to produce up to 96 % dimers from propene. Selectivities and activities were influenced by varying the compositions of the ionic liquids. Furthermore, buffer addition reduced the melting points of the resulting liquids. This effect allowed a screening of many different organic halide salts, which were found to strongly influence the lifetimes and selectivities of the corresponding biphasic olefin dimerization systems. An optimized system dimerized ethene, propene, 1‐butene, and 1‐hexene with high selectivities. It is even possible to recycle amines and buffers used for these compositions by a simple acid base extraction of the spent ionic liquid catalyst systems. We also proposed a mechanism for these NiII catalyzed selective olefin dimerization reactions in alkylaluminum free buffered chloroaluminate melts. The addition of small amounts of BiPh3 to an ionic liquid composition used in the commercial DIFASOL process increased the selectivity to give dimers from a biphasic propene dimerization reaction by 15 %.
Light‐Driven Uncoupling of Nitrogenase Catalysis from ATP Hydrolysis
Authors: Roth Lauren E. , Tezcan F. Akif 
Published: September 2011

AbstractAs the sole artificial means to catalyze the reduction of atmospheric N2 to NH3, the Haber–Bosch process carries an enormous industrial and agricultural importance. Yet, despite being developed nearly a century ago and its immense economic and environmental cost, no cleaner or more efficient alternative to this process has been found. Biological nitrogen fixation catalyzed by nitrogenase is an enticing place to look for inspiration for an alternative catalyst. However, this enzyme’s catalytic mechanism is poorly understood, because it relies upon ATP hydrolysis and protein interactions to coordinate electron transfer and substrate activation, creating a complex mixture of redox intermediates during turnover. Recently, new approaches have been presented to circumvent this problem. One such possibility is the use of covalently attached photosensitizers to directly transfer electrons to the active site of the enzyme, thereby uncoupling substrate reduction from ATP hydrolysis and allowing the population of discrete reaction intermediates for structural or spectroscopic investigation.
Structural Features and Hydrogen‐Bond Properties of Galanthamine and Codeine: An Experimental and Theoretical Study
Authors: Atkinson Alexandre P. , Baguet Evelyne , Galland Nicolas , Le Questel Jean‐Yves , Planchat Aurélien , Graton Jérôme 
Published: September 2011

AbstractStructural features of galanthamine and codeine, two allosteric potentiating ligands of nicotinic acetylcholine receptors (nAChRs), have been investigated through experimental studies in solution by FTIR and NMR spectroscopy and by quantum chemical calculations in the isolated state. The infrared spectra accumulated in solvents of various polarities show that the intramolecular OH⋅⋅⋅O hydrogen bond in galanthamine is stronger than the corresponding interaction in codeine. Molecular electrostatic potential calculations allow rationalisation of the experimental trends. NOE measurements on the two ligands in the same solvent range show significant differences. In apolar solvents, the NMR spectroscopic data indicate the occurrence of CH⋅⋅⋅O hydrogen‐bond interactions, whereas in the more polar solvents, a trans orientation of the methoxy group with respect to the furanyl oxygen atom is favoured. A natural bond orbital (NBO) analysis provides evidence that these stabilising interactions originate in the hyperconjugation between the lone pairs of the furanyl oxygen atoms, n(O), and the methoxy antibonding σ*(CH) orbitals within the two molecules. Despite the strong structural similarities between the two allosteric modulators, FTIR equilibrium constants measurements of hydrogen‐bond complexation combined with quantum chemistry calculations point out the significant increase of hydrogen‐bond accepting strength of galanthamine relative to codeine. This increase is mainly assignable to the stronger hydrogen‐bond basicity of the hydroxyl group, and to a lesser extent to the higher hydrogen‐bond accepting strength of the amino nitrogen of galanthamine in comparison with the corresponding groups of codeine. An analysis of the interactions that occur between the two ligands and acetylcholine esterase (AChE) suggests significant differences with Trp84, a key component of the AChE catalytic active site. In contrast, both ligands appear to interact similarly with acetylcholine binding protein (AChBP).
Conjugated Asymmetric Donor‐Substituted 1,3,5‐Triazines: New Host Materials for Blue Phosphorescent Organic Light‐Emitting Diodes
Authors: An Zhong‐Fu , Chen Run‐Feng , Yin Jun , Xie Guo‐Hua , Shi Hui‐Fang , Tsuboi Taiju , Huang Wei 
Published: September 2011

AbstractConjugated asymmetric donor‐substituted 1,3,5‐triazines (ADTs) have been synthesized by nucleophilic substitution of organolithium catalyzed by [Pd(PPh3)4]. Theoretical and experimental investigations show that ADTs possess high solubility and thermostability, high fluorescent quantum yield (35 %), low HOMO (−6.0 eV) and LUMO (−2.8 eV), and high triplet energy (ET, 3.0 eV) according to the different substitution pattern of triazine. The application as host materials for blue PHOLEDs yielded a maximum current efficiency of 20.9 cd A−1, a maximum external quantum efficiency of 9.8 %, and a brightness of 9671 cd m−2 at 5.4 V, making ADTs good candidates for optoelectronic devices.
WaterLOGSY NMR Experiments in Conjunction with Molecular‐Dynamics Simulations Identify Immobilized Water Molecules That Bridge Peptide Mimic MDWNMHAA to Anticarbohydrate Antibody SYA/J6
Authors: Szczepina Monica G. , Bleile Dustin W. , Müllegger Johannes , Lewis Andrew R. , Pinto B. Mario 
Published: September 2011

AbstractX‐ray crystallographic data of the carbohydrate mimic MDWNMHAA when bound to an anti‐Shigella flexneri Y mAb SYA/J6 indicate the immobilization of water molecules, that is, the presence of “bound” waters, in the active site. Water Ligand Observed via Gradient Spectroscopy (WaterLOGSY) was used in conjunction with saturation transfer difference (STD)‐NMR spectroscopy to probe the existence of immobilized water molecules in the complex of MDWNMHAA 1 bound to mAb SYA/J6. Molecular dynamics simulations using the ZymeCAD Molecular Dynamics platform were then used to specify the likely locations of these water molecules. Of note, those waters involved in providing complementarity between the peptide and mAb SYA/J6 remained throughout the course of the simulation. Together, the experimental and computational protocols have been used to identify the bound water molecules present in the antibody‐peptide complex.
Construction of Hydrogen‐Bonded Ternary Organic Crystals Derived from L‐Tartaric Acid and Their Application to Enantioseparation of Secondary Alcohols
Authors: Kodama Koichi , Sekine Eriko , Hirose Takuji 
Published: September 2011

AbstractTernary organic crystals consisting of an L‐tartaric acid‐derived dicarboxylic acid, a commercially available achiral diamine, and a chiral secondary alcohol have been developed and characterized by X‐ray crystallography. 1D, 2D, and 3D hydrogen‐bonded supramolecular networks were constructed, depending on the structure of the diamine used. Benzylic and aliphatic secondary alcohols were enantioselectively incorporated into the crystal and were successfully enantioseparated with up to 86 and 79 % enantiomeric excess (ee), respectively. Selective incorporation of one enantiomer of 2‐butanol, which is a small chiral aliphatic alcohol, was achieved by the cooperative effects of hydrogen bonds, CH⋅⋅⋅π interactions, and van der Waals interactions between the guest and host molecules, with the aid of two water molecules. The high host potential of the binary supramolecular system is mainly attributed to the skewed conformation of two rigid aromatic groups of tartaric acid derivatives, which prevents dense packing of the molecules and enhances the formation of multicomponent inclusion crystals.
Flocculation–Sedimentation Combined with Chemical Oxidation Process
Authors: Nieto Leopoldo Martínez , Hodaifa Gassan , Rodríguez Salvador , Giménez José A. , Ochando Javier 
Published: September 2011

AbstractFlocculation and sedimentation of particles are essential to many environmental and industrial processes. Solid–liquid separation in olive‐oil mill wastewater treatment by means of Fenton system is the key to work continuously and maintain a constant outlet flow of clarified water at the end of the oxidation process. Natural sedimentation is not capable to eliminate the sludge formed. The efficiency of flocculation operation using different flocculants as QG‐2001, QG‐2002, DQGALFLOC‐130H, and Nalco‐77171 was investigated. The optimum dosage of each flocculant, 150, 2.5, 66, and 6 mg dm−3, respectively, was determined. The results revealed that the best flocculant was Nalco‐77171, which determined 13.5% v/v final sludge separation and 86.5% v/v final clarified water obtained. Kinetics of sludge removal in the transition zone was adjusted to power law, v/v0 = Ktε, where the exponent, ε, varied in the range 0.141–0.670.
Bipolar Vulnerability and Extreme Appraisals Of Internal States: A Computerized Ratings Study
Authors: Dodd Alyson L. , Mansell Warren , Morrison Anthony P. , Tai Sara 
Published: September 2011

A recent integrative cognitive model proposed that multiple, extreme, personalized, positive and negative appraisals of internal states predispose to maintain and exacerbate bipolar symptoms. This study aimed to directly assess conviction in a range of positive and negative appraisals of internal states suggested by the model, by using a laboratory‐based computerized task. In a student sample (n = 68), a history of hypomania was associated with more positive and less negative appraisals of internal states, and a history of depression was associated with more negative appraisals and less positive appraisals of internal states. The sample was then split into three groups for comparison: bipolar risk (n = 18), depression risk (n = 20) and controls (n = 30). Relative to controls, the bipolar risk group made more extreme ratings of catastrophic appraisals of low activation states and tended to make more extreme ratings of appraisals of high activation states. The depression risk group scored higher on a range of negative appraisals of low activation states. These findings provide tentative support for the role of both positive and negative, extreme, personalized appraisals of internal states in hypomania and depression. Copyright © 2011 John Wiley & Sons, Ltd.Key Practitioner Message

This study investigates putative cognitive vulnerability factors for both hypomania and depression.
A number of associations were found between positive and negative appraisals of internal states and both a history of hypomania and depression.
These results complement previous findings in both analogue and clinical populations that extreme, personalized, positive and negative appraisals of internal states are associated with bipolar symptomatology.
Taken together, these findings could translate into practice, as these appraisals could be targeted in psychological interventions.
Advanced Roll‐to‐Roll Plasma‐Enhanced CVD Silicon Carbide Barrier Technology for Protection from Detrimental Gases
Authors: Zambov L. , Shamamian V. , Weidner K. , Loboda M. 
Published: September 2011

AbstractThe demand for low‐cost transparent gas and moisture barrier materials initiates many activities in the area of roll‐to‐roll (R2R), CVD, thin film technology. The present article is an overview on the elaboration of plasma‐enhanced (PE)CVD technology for R2R manufacturing of amorphous silicon carbide (SiC) barrier coatings applied on polymers. A prototype R2R PECVD reactor is designed and built for uniform coatings deposition on large area web‐substrates. A key feature is the incorporation of the Penning discharge plasma source (PDPS) to provide magnetically confined, high‐density plasma (HDP) with no excessive heat. Coatings are grown on a variety of polymer substrates using trimethylsilane ((CH3)3SiH) as the main organic precursor for delivery of active SiC species in the gas phase during deposition. A variety of analytical techniques are utilized to correlate process operating factors and plasma chemistry with coating composition and properties, in particular with the barrier performance and durability of barrier coated films (BCFs). The developed R2R PECVD technology demonstrates significant achievements in barrier performance with water vapor transmission rate (WVTR) of less than 5 × 10−4 g m−2 day−1 and durability of BCFs for more than 500 h under damp‐heat conditions of 85 °C and 85% relative humidity (RH). Manufactured BCFs can be competitively implemented for protection against detrimental gasses in various applications, such as drug and food packaging, and flexible electronic devices, such as thin film batteries and solar cells, liquid‐crystal (LCD), and light‐emitting diode (LED) displays.
An ant colony optimisation algorithm for aggregated multicast based on minimum grouping model
Authors: Zhu Fangjin , Wang Hua 
Published: September 2011

SUMMARYThe tree‐based delivery structure of the traditional Internet protocol multicast requires each on‐tree router to maintain a forwarding state for a group. This leads to a state scalability problem when large numbers of concurrent groups exist in a network. To address this state scalability problem, a novel scheme called aggregated multicast has recently been proposed, in which multiple groups are forced to share one delivery tree. In this paper, we define the aggregated multicast problem based on the minimum grouping model, and propose an ant colony optimisation algorithm. The relative fullness of the tree is defined according to the characteristics of the minimum grouping problem and is introduced as an important component in identifying the aggregation fitness function between two multicast groups. New pheromone update rules are designed based on the aggregation fitness function. To improve the convergence time of the algorithm, we use the changes (brought by each group) in the relative fullness of the current tree as the selection heuristic information. The impact of the relative fullness of the tree is analysed using the hypothesis test, and simulation results indicate that introducing relative fullness to the fitness function can significantly improve the optimisation performance of the algorithm. Compared with other heuristic algorithms, our algorithm has better optimisation performance and is more suitable for scenarios with larger bandwidth waste rates. Copyright © 2011 John Wiley & Sons, Ltd.
Extracellular matrix and perineuronal nets in CNS repair
Authors: Kwok Jessica C.F. , Dick Gunnar , Wang Difei , Fawcett James W. 
Published: September 2011

AbstractA perineuronal net (PNN) is a layer of lattice‐like matrix which enwraps the surface of the soma and dendrites, and in some cases the axon initial segments, in sub‐populations of neurons in the central nervous system (CNS). First reported by Camillo Golgimore than a century ago, the molecular structure and the potential role of this matrix have only been unraveled in the last few decades. PNNs are mainly composed of hyaluronan, chondroitin sulfate proteoglycans, link proteins, and tenascin R. The interactions between these molecules allow the formation of a stable pericellular complex surrounding synapses on the neuronal surface. PNNs appear late in development co‐incident with the closure of critical periods for plasticity. They play a direct role in the control of CNS plasticity, and their removal is one way in which plasticity can be re‐activated in the adult CNS. In this review, we examine the molecular components and formation of PNNs, their role in maturation andsynaptic plasticity after CNS injury, and the possible mechanisms of PNN action. © 2011 Wiley Periodicals, Inc. Develop Neurobiol 71: 1073‐1089, 2011
IL‐33 synergizes with TCR and IL‐12 signaling to promote the effector function of CD8+ T cells
Authors: Yang Qianting , Li Gang , Zhu Yibei , Liu Lin , Chen Elizabeth , Turnquist Hēth , Zhang Xueguang , Finn Olivera J. , Chen Xinchun , Lu Binfeng 
Published: September 2011

AbstractThe effector functions of CD8+ T cells are influenced by tissue inflammatory microenvironments. IL‐33, a member of the IL‐1 family, acts as a danger signal after its release during cell necrosis. The IL‐33/ST2 axis has been implicated in various Th2 responses. Its role in CD8+ T‐cell‐mediated immune response is, however, not known. Here we find that type 1 cytotoxic T (Tc1) cells cultured in vitro unexpectedly express high levels of the IL‐33 receptor ST2. Interestingly, the expression of ST2 in Tc1 cells is dependent on T‐bet, a master Th1/Tc1 transcription factor. In addition, IL‐33 enhances TCR‐triggered IFN‐γ production. IL‐33 together with IL‐12 can stimulate IFN‐γ production in Tc1 cells. Moreover, IL‐33 synergizes with IL‐12 to promote CD8+ T‐cell effector function. The synergistic effect of IL‐33 and IL‐12 is partly mediated by Gadd45b. Together, these in vitro data establish a novel role of IL‐33 in promoting effector type 1 adaptive immune responses.
A Phospha‐Wittig Route to 5‐Phosphaphenanthrene
Authors: Wang Huaiqiu , Zhao Weining , Zhou Yang , Duan Zheng , Mathey François 
Published: September 2011

AbstractThe reaction of tributylphosphane with a 7‐(2′‐formyl‐2‐biphenylyl)phosphanorbornadiene P‐W(CO)5 complex leads to the 5‐phosphaphenanthrene P‐W(CO)5 complex via an intramolecular phospha‐Wittig condensation. This complex is stable enough for detection by 31P NMR spectroscopy but cannot be isolated due to its high reactivity. It is trapped by addition of MeOH or cycloaddition with 2,3‐dimethylbutadiene or a nitrileimine. The adducts were characterized by X‐ray crystal structure analysis.
Synthesis, Structure, and C–C Cross‐Coupling Activity of (Amine)bis(phenolato)iron(acac) Complexes
Authors: Hasan Kamrul , Dawe Louise N. , Kozak Christopher M. 
Published: September 2011

AbstractA series of (amine)bis(phenolato)iron(III)acac complexes has been prepared and characterized. Reaction of Fe(acac)3 with the diprotonated linear tetradentate proligand N,N′‐bis(4,6‐di‐tert‐butyl‐2‐methylphenol)‐N,N′‐dimethyl‐1,2‐diaminoethane, H2[L1], and tripodal tetradentate ligand precursors dimethylaminoethylamino‐N,N‐bis(2‐methylene‐4,6‐di‐tert‐butylphenol), H2[L2], dimethylaminoethylamino‐N,N‐bis(2‐methylene‐4‐methyl‐6‐tert‐butylphenol), H2[L3], 2‐methoxyethylamino‐N,N‐bis(2‐methylene‐4,6‐di‐tert‐butylphenol), H2[L4], 2‐methoxyethylamino‐N,N‐bis(2‐methylene‐4‐methyl‐6‐tert‐butylphenol), H2[L5], and 2‐methoxyethylamino‐N,N‐bis(2‐methylene‐4,6‐dimethylphenol), H2[L6], produces the distorted octahedral FeIII complexes [L1]Fe(acac) (1), [L2]Fe(acac) (2), [L3]Fe(acac) (3), [L4]Fe(acac) (4), [L5]Fe(acac) (5), and [L6]Fe(acac) (6). In all of these complexes, the phenolato oxygen atoms are cis‐oriented. The paramagnetic FeIII complexes 1–6 were also characterized by UV/Vis and IR spectroscopy, mass spectrometry, cyclic voltammetry, and magnetic measurements. Single crystal X‐ray molecular structures have been determined for complexes 1, 2, 3, 5, and the proligand H2[L6]. Preliminary investigations of complexes 1–6 for catalytic cross‐coupling reactions of aryl Grignard reagents with cyclic and acyclic secondary alkyl halides and benzyl halides were performed. While the activity for cyclohexyl chlorides and bromides was high, cross‐coupling of benzyl halides was moderate and 2‐bromo‐ and 2‐chlorobutane gave poor yields of cross‐coupled product.
Small Substituents Make Large Differences: Aminopyrimidinyl Phosphanes Undergoing C–H Activation
Authors: Farsadpour Saeid , Ghoochany Leila Taghizadeh , Sun Yu , Thiel Werner R. 
Published: September 2011

AbstractPalladium complexes synthesised from (C6H5CN)2PdCl2and (2‐aminopyrimidinyl)phosphanes show different coordination modes depending on the nature of the amino substituent attached to the pyrimidine ring. WhereasP,N‐coordination is observed for primary and secondary amino groups, tertiary amino groups lead to C–H activation at the pyrimidine ring. These differences result in strongly different catalytic activities in the Suzuki–Miyaura coupling reaction. The palladium complexes were characterised spectroscopically and bymeans of X‐ray structural analysis. DFT calculations were carried out to differ between the electronic and steric effects that are responsible for their behaviour in catalysis.
Standardization of vegetable oils composition to be used as oleochemistry feedstock through a selective hydrogenation process
Authors: Zaccheria Federica , Psaro Rinaldo , Ravasio Nicoletta , Bondioli Paolo 
Published: September 2011

AbstractSelective hydrogenation over pre‐reduced 8% Cu/SiO2 catalysts has been carried out on a series of non‐food oils methylesters. The catalyst shows a very high diene:monoene selectivity, thus allowing one to reduce not only the linolenic component, but also the linoleic one in this way enriching the oil in oleic acid and avoiding a contemporary increase in stearic acid concentration. This treatment improves the oxidation stability of the oil while keeping acceptable viscosity and cold properties and can be used to standardize a wide variety of different available feedstock.Practical applications: Vegetable oils from different sources can be used as primary, secondary (when they are residues of other processes), or tertiary (post‐consumer wastes) feedstock for the chemical industry. Their composition can be very different as far as unsaturated components are concerned. This variability is an issue because it can lead to multiple products and moreover the unsaturation level, that is the iodine value, is strongly related to oxidation unstability. The process we propose here allows one to standardize the oil composition improving the oxidation stability and keeping acceptable fluidity. The very mild experimental conditions, 4–6 atm of H2 and 160–180°C, the use of a non‐toxic and cheap metal, make this process sustainable and easily viable, e.g., in hardening plants.
5,6‐Dihydroxyindole Chemistry: Unexplored Opportunities Beyond Eumelanin
Authors: d'Ischia Marco , Napolitano Alessandra , Pezzella Alessandro 
Published: September 2011

Abstract5,6‐Dihydroxyindoles, the key building blocks of eumelanin biopolymers, hold promise as versatile molecular systems for the design and development of new functional aromatic scaffolds, biomimetic polymers, and nanomaterials with tailored optical and electronic properties. During the past decade, research into the photophysics, synthesis, π electron manipulation, and reaction behavior of 5,6‐dihydroxyindoles has expanded beyond the traditional boundaries of biology and medicine to involve physicists, organic chemists, and materials scientists. This review presents the latest advances in 5,6‐dihydroxyindole chemistry from a new perspective. Touching only upon themes at the periphery of eumelanin research, it seeks rather to throw light on the chemical and photophysical features of this peculiar π electron system as an unexplored conceptual and practical platform on which synthetic creativity and rational design might generate a range of chemically diverse molecular scaffolds.