bluuebunny/crossref_metadata_2025_split huggingface dataset:
Oxidative Asymmetric Aza‐Friedel–Crafts Alkylation of Indoles with 3‐Indolinone‐2‐carboxylates Catalyzed by a BINOL Phosphoric Acid and Promoted by DDQ
Authors: Yarlagadda Suresh , Sridhar B. , Subba Reddy Basireddy Venkata 
Published: March 2018

AbstractAn asymmetric aza‐Friedel–Crafts alkylation reaction between indoles and indolenines that were derived in situ from 3‐indolinone‐2‐carboxylates has been developed by using 3,3′‐bis(triphenylsilyl)‐1,1′‐binaphthyl‐2,2′‐diyl hydrogen phosphate as a catalyst. The reaction proceeded under mild conditions and provided chiral indol‐3‐yl‐3‐indolinone‐2‐carboxylate derivatives in good yields with excellent ee values (up to 98.6 %). Similarly, the Mannich‐type addition of indoline‐3‐ones to indolenines provided heterodimers with vicinal chiral quaternary centers. This method was successfully applied to the construction of the core structure of trigonoliimine C.
Pinning Cluster Synchronization of Coupled Nonidentical Harmonic Oscillators Under Directed Topology
Authors: Zhao Liyun , Wu Quanjun , Wang Rui 
Published: March 2018

AbstractThis paper addresses cluster synchronization of coupled harmonic oscillators over directed fixed and switching topologies, where uncoupled harmonic oscillators in the same cluster have the identical node dynamics, while any pair of nodes in different clusters are essentially distinguishing according to their local dynamics. A pinning control protocol is proposed for such coupled harmonic oscillators system, and then some graphic topology conditions easy to verify are established for cluster synchronization. The main contributions of the present investigation include: (i) cluster synchronization problem of coupled nonidentical harmonic oscillators is addressed over directed topology; (ii) desynchronizing motion of harmonic oscillators from different clusters doesn't depend on negative coupling weights but leader of every cluster; (iii) this paper deals with what kind of harmonic oscillators ought to be pinned in order to reach cluster synchronization. Finally, numerical examples and simulations demonstrate the obtained theoretical results.
Spectral evolution of the two classical novae PW Vul and V1668 Cyg using International Ultraviolet Explorer low‐resolution spectra
Authors: Hamed G. M. , Sanad M. R. , Yousef S. , Essam A. , El Rafy M. 
Published: March 2018

We studied the evolution of the normalized flux of selected ultraviolet (UV) emission lines of two classical novae (PW Vul and V1668 Cyg) using International Ultraviolet Explorer (IUE) short wavelength observations. Different phases of the outburst are studied. Emission lines covering a wide range of ionization states are investigated. We use the calculated fluxes to estimate the mass accretion rates during quiescence of both novae. We found average values of the UV luminosity for PW Vul to be of 1.0 ± 0.1 × 1035 erg s−1, and the corresponding value for V1668 Cyg is 4.0 ± 0.2 × 1035 erg s−1. In quiescence, we obtained average values for the mass accretion rates of 8.7 ± 0.4 × 10−10 M⊙ year−1 and 1.8 ± 0.1 × 10−10 M⊙ year−1, respectively. We attribute the spectral behavior of the two systems to the variation of the optical thickness and temperature of the envelope during the different phases of the outburst. Our results demonstrate the effect of the white dwarf mass on the evolution of the nova. The results of IUE observations are consistent with the theoretical CO models of classical nova of.
Detachment of ligands from nanoparticle surface under flow and endothelial cell contact: Assessment using microfluidic devices
Authors: Jarvis Maria , Arnold Michael , Ott Jenna , Krishnan Vinu , Pant Kapil , Prabhakarpandian Balabhaskar , Mitragotri Samir 
Published: March 2018

AbstractSurface modification of nanoparticles is a well‐established methodology to alter their properties to enhance circulation half‐life. While literature studies using conventional, in vitro characterization are routinely used to evaluate the biocompatibility of such modifications, relatively little attention has been paid to assess the stability of such surface modifications in physiologically relevant conditions. Here, microfluidic devices were used to study the effect of factors that adversely impact surface modifications including vascular flow and endothelial cell interactions. Camptothecin nanoparticles coated with polyethylene glycol (PEG) and/or folic acid were analyzed using linear channels and microvascular networks. Detachment of PEG was observed in cell‐free conditions and was attributed to interplay between the flow and method of PEG attachment. The flow and cells also impacted the surface charge of nanoparticles. Presence of endothelial cells further increased PEG shedding. The results demonstrate that endothelial cell contact, and vascular flow parameters modify surface ligands on nanoparticle surfaces.
Online shopping experience in an emerging e‐retailing market: Towards a conceptual model
Authors: Izogo Ernest Emeka , Jayawardhena Chanaka 
Published: March 2018

AbstractWe develop a comprehensive and integrated framework of online shopping experience (hereafter OSE) from an emerging market perspective. Using a netnographic research method, we content analysed 284 experiential reviews of 2 leading Nigerian e‐retailers. Augmented by the theory of customer engagement, we identify 8 dimensions of OSE that activate shoppers' affective and cognitive states, which consequently lead to 4 behavioural outcomes, namely, internal responses to service experience, external responses to service experience, repurchase intentions, and word of mouth intentions. The proposed dynamic and comprehensive framework reflects all phases of the consumer decision‐making process and demonstrates that OSE has both perceptual and behavioural components. We make 3 important contributions. First, the paper provides a comprehensive and dynamic model of customer experience that encompasses all the stages in the customer decision‐making process by drawing on a new theoretical perspective to demonstrate how the unique attributes of OSE contribute to extant customer experience research. Second, we advance experiential consumption theory by incorporating attributes of OSE evolved through a unique qualitative research method into existing frameworks of customer experience. Third, we compare and contrast findings from an emerging market with research from more mature markets, when they were undergoing similar development patterns. From a managerial perspective, we illustrate how online retailers operating in emerging markets can draw from the experiences of mature markets and understand the key differences between markets so that they can develop customer experience management strategies by concentrating on the most important components of customer experience.
Pseudoaneurysm of the left main coronary artery: A complication of orbital atherectomy
Authors: Tapias Luis F. , Campbell Joseph , Rosenfield Kenneth , D'Alessandro David A. 
Published: March 2018

AbstractPlaque modification devices are used to treat heavily calcified coronary artery lesions during percutaneous coronary artery interventions. As these devices have unique risk profiles, clinicians need to be aware of potential complications associated with their use. A case of a contained rupture (i.e., pseudoaneurysm) of the proximal left main coronary artery following orbital atherectomy is presented. This lesion was managed with coronary artery bypass grafting and oversewing of the left main coronary artery ostium. This case illustrates that lesion location and configuration may influence tracking of these devices, as well as the actual site of tissue ablation. This case underscores the importance of concurrent imaging during treatment and concern for potential unintended consequences of atherectomy.
Effect of different lipases on bread staling in comparison with Diacetyl tartaric ester of monoglycerides (DATEM)
Authors: Frauenlob Johannes , Scharl Marlies , D'Amico Stefano , Schoenlechner Regine 
Published: March 2018

Background and objectivesLipases are applied in breadmaking as an enzymatic replacement for typical bakery surfactants like Diacetyl tartaric ester of monoglycerides (DATEM) (diacetyl tartaric ester of monoglycerides). In this study, the influence of six commercially available lipases and DATEM on bread staling and bread height was investigated. Therefore, a microbaking experiment was conducted, where 15 g of dough was used for each bread. Microbaking breads were analyzed for height, baking loss, and crumb firmness. Evolution of crumb firmness was measured seven times during a storage period of up to 10 days, under a controlled atmosphere (20°C).FindingsAll additives increased bread height significantly in comparison with the control (without DATEM and lipase). Maximum height was achieved by addition of DATEM. All additives had a significant antistaling effect in comparison with the control. The lowest bread firmness throughout the whole storage period was achieved by addition of DATEM. Between the six lipases significant differences existed, suggesting a diverse influence of their lipid products on bread staling and bread height.ConclusionsTaken together, none of the lipases was able to replace DATEM without the occurrence of reduced bread height and worsened staling behavior at the applied concentrations.Significance and noveltyAlthough lipase addition in general had a positive effect on increasing bread height and retarding staling, it has to be considered in future work that none of the studied lipases was able to replace DATEM and great differences between the single lipases existed.
Nature of Sintering‐Resistant, Single‐Atom Ru Species Dispersed on Zirconia‐Based Catalysts: A DFT and FTIR Study of CO Adsorption
Authors: Thang Ho Viet , Tosoni Sergio , Fang Liu , Bruijnincx Pieter , Pacchioni Gianfranco 
Published: March 2018

AbstractRecent studies on the upgrade of cellulosic biomass to renewable chemicals and fuels based on Ru/ZrO2 catalysts have shown that the catalyst contains atomically dispersed, highly stable Ru atoms. FTIR spectra after CO dosage reveal a complex manifold of bands resulting from Ru‐CO carbonyl species. The nature of the atomically dispersed Ru species on monoclinic zirconia, and the origin of their thermal stability are the object of this investigation. Combining density functional theory (DFT) calculations on model systems of both tetragonal and monoclinic ZrO2, with novel experimental data, we provide a basis for the identification of the monoatomic Ru species. Various candidates are explored based on DFT calculations of their intrinsic stability and of the vibrational properties of adsorbed CO probe molecules. The results allow us to discard a number of possible structures, and restrict the analysis to a few potential candidates. Most likely, the atomically dispersed sites result from the interaction of Ru atoms with one OH group of the surface with elimination of H2 by condensation, leaving RuO species strongly bound to the zirconia surface. CO binds strongly to the RuO units forming (RuO)(CO)2 geminal complexes with characteristic signatures in terms of CO vibrational frequency. Despite the formal positive oxidation state of the Ru species, large negative shifts are found in the CO stretching frequency compared with the free CO molecule.
Homogeneous Copper‐Catalyzed Conversion of Methane to Methyl Trifluoroacetate in High Yield at Low Pressure
Authors: Ravi Manoj , van Bokhoven Jeroen A. 
Published: March 2018

AbstractThe direct catalytic oxidation of methane to oxygenates, a reaction that garners significant scientific and industrial interest, is plagued by poor methane‐based yields. Some of the best homogeneous catalytic systems reported to date convert methane to methyl esters using catalysts with complex organic ligands to reach high yields at relatively high temperature (>423 K) and pressure (20–70 bar). In our study, we used a simple copper compound, copper(II) oxide, to selectively convert methane to methyl trifluoroacetate at 363 K and low pressure (5 bar) resulting in yields as high as 63 % at a methane conversion of 71 %. The catalyst is easily recovered by treating the spent reaction mixture with a base, and the catalytic performance of the recovered material is highly comparable to that of the fresh catalyst. In terms of turnover, copper oxide (TON=33 for ester yield of 56 %) ranks higher than other simple metal compounds and is comparable to catalysts with NHC ligands. Thus, this work demonstrates the possibility of using a simple catalyst devoid of complex ligands to convert methane in high yields at low pressure.
A Magnetic Chameleon: Biocompatible Lanthanide Fluoride Nanoparticles with Magnetic Field Dependent Tunable Contrast Properties as a Versatile Contrast Agent for Low to Ultrahigh Field MRI and Optical Imaging in Biological Window
Authors: Biju Silvanose , Gallo Juan , Bañobre‐López M. , Manshian Bella B. , Soenen Stefaan J. , Himmelreich Uwe , Vander Elst Luce , Parac‐Vogt Tatjana N. 
Published: March 2018

AbstractA novel type of multimodal, magnetic resonance imaging/optical imaging (MRI/OI) contrast agent was developed, based on core–shell lanthanide fluoride nanoparticles composed of a β‐NaHoF4 core plus a β‐NaGdF4:Yb3+, Tm3+ shell with an average size of ∼24 nm. The biocompatibility of the particles was ensured by a surface modification with poly acrylic acid (PAA) and further functionalization with an affinity ligand, folic acid (FA). When excited using 980 nm near infrared (NIR) radiation, the contrast agent (CA) shows intense emission at 802 nm with lifetime of 791±3 μs, due to the transition 3H4→3H6 of Tm3+. Proton nuclear magnetic relaxation dispersion (1H‐NMRD) studies and magnetic resonance (MR) phantom imaging showed that the newly synthesized nanoparticles, decorated with poly(acrylic acid) and folic acid on the surface (NP‐PAA‐FA), can act mainly as a T1‐weighted contrast agent below 1.5 T, a T1/T2 dual‐weighted contrast agent at 3 T, and as highly efficient T2‐weighted contrast agent at ultrahigh fields. In addition, NP‐PAA‐FA showed very low cytotoxicity and no detectable cellular damage up to a dose of 500 μg mL−1.
How Mycobacterium tuberculosis Galactofuranosyl Transferase 2 (GlfT2) Generates Alternating β‐(1–6) and β‐(1–5) Linkages: A QM/MM Molecular Dynamics Study of the Chemical Steps
Authors: Janoš Pavel , Kozmon Stanislav , Tvaroška Igor , Koča Jaroslav 
Published: March 2018

AbstractMycobacterium tuberculosis features a unique cell wall that protects the bacterium from the external environment. Disruption of the cell wall assembly is a promising direction for novel anti‐tuberculotic drugs. A key component of the cell wall is galactan, a polysaccharide chain composed of galactofuranose (Galf) units connected by alternating β‐(1–5) and β‐(1–6) linkages. The majority of the galactan chain is biosynthesized by a bifunctional enzyme—galactofuranosyl transferase 2 (GlfT2). GlfT2 catalyzes two reactions: the formation of β‐(1–5) and β‐(1–6) linkages. It was suggested that the enzyme acts through a processive mechanism until it adds 30–35 Galf units in a single active site. We applied a QM/MM string method coupled with ab initio molecular dynamics simulations to study the two reactions catalyzed by GlfT2. We showed that both reactions proceed very similarly and feature similar transition‐state structures. We also present novel information about the ring puckering behavior of the five‐membered furanose ring during the glycosyltransferase reaction and a calculated transition‐state structure with galactose in a furanose form that may be used as a guide for the rational design of very specific and extremely potent inhibitors, that is, transition‐state analogues, for GlfT2. Due to the absence of a furanose form of galactose in humans, transition‐state‐analogous inhibitors represent an attractive scaffold for the development of novel antibacterial drugs.
Asymmetric Synthesis of Diarylmethyl Sulfones by Palladium‐Catalyzed Enantioselective Benzylic Substitution: A Remarkable Effect of Water
Authors: Najib Atifah , Hirano Koji , Miura Masahiro 
Published: March 2018

AbstractA Pd/(R)‐BINAP‐catalyzed enantioselective benzylic sulfonation of diarylmethyl carbonates with sodium sulfinates proceeds to deliver the corresponding chiral diarylmethyl sulfones in good yields with high enantioselectivity. The reaction occurs in a dynamic kinetic asymmetric transformation (DYKAT) manner and thus provides convergent access to optically active benzylic sulfones from racemic secondary benzylic carbonates. Additionally, the addition of H2O is found to be critical for high enantioselectivity.
Gold(III) Complexes for Antitumor Applications: An Overview
Authors: Bertrand Benoît , Williams Morwen R. M. , Bochmann Manfred 
Published: March 2018

AbstractGold(III) complexes have emerged as a versatile and effective class of metal‐based anticancer agents. The development of various types of ligands capable of stabilizing the AuIII cation and preventing its reduction under physiological conditions, such as chelating nitrogen‐donors, dithiocarbamates and C^N cyclometalled ligands, has opened the way for the exploration of their potential intracellular targets and action mechanisms. At the same time, the bioconjugation of AuIII complexes has emerged as a promising strategy for improving the selectivity of this class of compounds for cancer cells over healthy tissues, and recent developments have shown that combining gold complexes with molecular structures that are specifically recognized by the cell can exploit the cell's own transport mechanisms to improve selective metal uptake.
Mechanical Switching of Aromaticity and Homoaromaticity in Molecular Optical Force Sensors for Polymers
Authors: Stauch Tim 
Published: March 2018

AbstractThe sensing of mechanical stress in polymers is indispensable for investigating the origin and propagation of cracks that lead to material failure and for designing mechanically responsive polymers. Here the unique approaches of using the force‐induced switching of aromaticity and homoaromaticity in molecular optical force sensors for the real‐time measurement of mechanical forces acting in stretched polymers are suggested. The mechanical switching of aromaticity in Dewar benzene is an irreversible event, whereas the degree of π‐orbital overlap in homoaromatic compounds like homotropylium can be adjusted progressively over a wide range of forces. Using computational methods, it is demonstrated that both approaches lead to significant changes in the visible part of the UV/Vis spectra of the force sensors upon application of weak forces (pN–nN). Polymers that incorporate such molecular force sensors therefore change their color well before material failure occurs.
Hierarchical Self‐Assembly Induced by Dilution‐Enhanced Hydrophobic Hydration
Authors: Liu Dapeng , Wang Xiaosong 
Published: March 2018

AbstractHydrophobic hydration (HH) is crucial in protein chemistry. Its role in the organization of molecules in water, however, remains elusive and difficult to investigate without appropriate model systems. Metal carbonyl vesicles (MCsomes), assembled from hydrophobic Fp(CH2)6Azobenzenetrans (Fp head=(PPh3)(Cp)Fe(CO)(CO‐); hydrocarbon tail=(CH2)6Azobenzenetrans; trans:trans configuration) is dispersible in water via HH of the Fp heads. We examined the dependence of this HH on solution conditions by taking advantage of redox activity and fluorescence quenching ability of hydrated Fe elements. A subtle variation in the HH substantially varied the solution behaviour of the MCsomes for hierarchical structural evolutions. This scrutiny resolved a long‐standing challenge to explicate the role of HH in self‐assembly at molecular levels, an imperative step to understand the biological systems.
Preparation of Ammonia from Liquid AdBlue – Modeling Approaches and Future Challenges
Authors: Lauer Thomas 
Published: March 2018

AbstractSustainable mobility is a legal and public demand. An important measure to clean the exhaust gas of diesel engines is the conversion of nitric oxides with selective catalytic reduction (SCR). The development of SCR systems can be strongly supported by numerical methods. This review article is to document the status of the CFD‐simulation method with respect to the preparation of the injected urea‐water solution, the turbulent transport of ammonia and the assessment of solid deposits coming from liquid film. Comparisons with measurements for realistic sprays and mixing sections are given.
Hydrothermal dewatering of lignite water slurries: Part 2 surface properties and stability
Authors: Li Qiang , Yang Dingzheng , Liu Qingxia , Zhang Jiansheng 
Published: March 2018

AbstractIn this paper, the mechanism of the stability of lignite lignite water slurry after hydrothermal dewatering/treatment (HTD) was studied by the measurement of the yield stress and the fractal dimension of the slurry. The effects of HTD on the surface properties of low rank coal were characterized by the contact angle, zeta potential, and Fourier transform infrared (FTIR) spectroscopy. After HTD, the hydrophobic attraction between coal particles was found to increase, as shown by the increase of the contact angle, and the electrical double layer repulsion was found to decrease, due to the decrease of zeta potential. These effects lead to an increase on the inter‐particle attractions, which is also proven by the theoretical calculations on the interaction energy using the extended DLVO theory. The stability measurements show that the low rank coal water slurry (CWS) becomes more stable after HTD, which is probably due to the formation of a network structure (soft sediment) by coal aggregating across the whole volume of the slurry to prevent coal particles from settling down. The network structure (soft sediment) in coal water slurry after HTD was verified and quantified by the yield stress and fractal dimension. Our findings indicated that the static stability of coal water slurry may be acquired by the network structure of the aggregated coal particles.
Coal pyrolysis and gasification in a fluidized bed thermogravimetric analyzer
Authors: Samih Said , Chaouki Jamal 
Published: March 2018

AbstractThe kinetics and modelling of coal gasification were studied in the newly developed fluidized bed thermogravimetric analyzer. The total weight loss obtained from the fluidized bed reactor and the total gas product are in general agreement. The presented model for the micro‐fluidized bed reactor encompasses the kinetics of coal pyrolysis as well as the gasification reactions. For coal pyrolysis, the resulting activation energies for the individual gases were 34.7 to 59.8 kcal/mol. These values are 19 to 21 % lower than those found in the literature for similar coals. This decrease of the activation energies of the endothermic pyrolysis reactions is attributed to a gradient of temperature of 185 to 209 °C. The obtained activation energy for the CO shift reaction is 46.6 kcal/mol, increasing by 20 % from the one used in the literature. This increase of the activation energy of such a mildly exothermic reaction represents an equivalent of 170 °C gradient of temperature. The effects of temperature on the yield and the composition of the gas product are studied. Experimental results and equilibrium data are also compared. The model shows reasonably good agreement with the experimental results, except for the water gas shift reaction.