bluuebunny/crossref_metadata_2025_split huggingface dataset:
Interrupted Imino‐Nazarov Cyclization of 1‐Aminopentadienyl Cation and Related Cascade Process
Authors: William Ronny , Wang Siming , Ding Feiqing , Arviana Elise Nerissa , Liu Xue‐Wei 
Published: August 2014

AbstractFacile 4π conrotatory imino‐Nazarov cyclization of a 1‐aminopentadienyl cation generated from condensation an aldehyde and secondary aniline in the presence of a catalytic amount of a Lewis acid has been developed. Silver(I)‐catalyzed intramolecular arene trapping of the resulting cyclic oxyallyl cation leads to formation of tricyclic indoline‐fused cyclopentanone. The use of lanthanide salts allows transformation after the initial trapping to afford tetrahydroquinoline‐fused cyclopentenone in a concise manner.
Mechanism on the permeation of ethanol in nitrile gloves studied using positron annihilation lifetime spectroscopy
Authors: Pham Binh , Phalen Robert , Sasanuma Naoko , Dorsainvil Yacinthe , Tol Jacqueline , Zhang Renwu 
Published: August 2014

ABSTRACTPositron annihilation lifetime spectroscopy (PALS) was applied to study the mechanism of ethanol diffusion through commercial nitrile rubber gloves. Even though the untreated raw samples were very different in their colors and area densities (g/cm2), the correlation between the ethanol diffusion coefficient from permeation test and the free volume from PALS measurement is well consistent with the Vrentas‐Duda model. Via combining the PALS technique and the Vrentas‐Duda theory, it is revealed that (a) the diffusion coefficient is correlated to the number of free volume holes rather than the average size of holes, (b) the diffusion process is not regulated by the size of ethanol molecule but by the size of critical volume for polymer segments to migrate, (c) nitrile group does not present in the free volume hole where the diffusion of ethanol molecule takes place, but is embedded in polymer matrix, and therefore, does not directly interact with ethanol molecule, and (d) nitrile group affects the average size, but not the number of free volume holes. The experiment demonstrates that the PALS technique, being mainly used in pure academic researches, might have application in the glove industry due to its ability in measuring terminal free volume quantities, which are directly related to the permeation of small organic molecules through protective gloves. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41282.
Preadolescent Decision‐Making Competence Predicts Interpersonal Strengths and Difficulties: A 2‐Year Prospective Study
Authors: Weller Joshua A. , Moholy Maxwell , Bossard Elaine , Levin Irwin P. 
Published: August 2014

ABSTRACTRecent research has demonstrated that decision‐making competence (DMC), a latent construct reflecting individual differences in rational thought, is predictive of real‐world decision outcomes at various stages of life. This construct has been shown to be associated with concurrent and retrospective accounts of health‐risking behavior, but its predictive validity has yet to be demonstrated. In the present study, we examine this issue using a 2‐year prospective, multiple‐informant design. Specifically, we tested the degree to which preadolescent DMC (PA‐DMC) obtained at ages 10–11 years (Time 1; N = 101) predicted both self‐reports and caregiver reports of emotional, behavioral, and peer‐related difficulties obtained 2 years later (Time 2; N = 76). Holding variables such as numeracy and inhibitory control constant, lower Time 1 PA‐DMC scores predicted greater reported Time 2 psychosocial difficulties (i.e. peer, conduct, emotional, and hyperactivity/inattention problems). Additionally, higher PA‐DMC scores were associated with greater self‐reported prosocial behaviors at Time 2. These results highlight the utility of testing individual differences in rational responding. We discuss the potential for improving children's decision‐making processes. Copyright © 2014 John Wiley & Sons, Ltd.
Phenylboronate chromatography selectively separates glycoproteins through the manipulation of electrostatic, charge transfer, and cis‐diol interactions
Authors: Carvalho Rimenys J. , Woo James , Aires‐Barros M. Raquel , Cramer Steven M. , Azevedo Ana M. 
Published: August 2014

AbstractPhenylboronate chromatography (PBC) has been applied for several years, however details regarding the mechanisms of interactions between the ligand and biomolecules are still scarce. The goal of this work is to investigate the various chemical interactions between proteins and their ligands, using a protein library containing both glycosylated and nonglycosylated proteins. Differences in the adsorption of these proteins over a pH range from 4 to 9 were related to two main properties: charge and presence of glycans. Acidic or neutral proteins were strongly adsorbed below pH 8 although the uncharged trigonal form of phenylboronate (PB) is less susceptible to forming electrostatic and cis‐diol interactions with proteins. The glycosylated proteins were only adsorbed above pH 8 when the electrostatic repulsion between the boronate anion and the protein surface was mitigated (at 200 mM NaCl). All basic proteins were highly adsorbed above pH 8 with PB also acting as a cation‐exchanger with binding occurring through electrostatic interactions. Batch adsorption performed at acidic conditions in the presence of Lewis base showed that charge‐transfer interactions are critical for protein retention. This study demonstrates the multimodal interaction of PBC, which can be a selective tool for separation of different classes of proteins.
Gold‐Catalyzed Cycloisomerization of 1,6,8‐Dienyne Carbonates and Esters to cis‐Cyclohepta‐4,8‐diene‐Fused Pyrrolidines
Authors: Rao Weidong , Sally  , Berry Stuart Neil , Chan Philip Wai Hong 
Published: August 2014

AbstractA synthetic approach that provides access to cis‐cyclohepta‐4,8‐diene‐fused pyrrolidines efficiently through AuI‐catalyzed cycloisomerization of 1,6,8‐dienyne carbonates and esters at a low catalyst loading of 2 mol % is reported. Starting carbonates and esters with a pendant alkyl group on the terminal alkenyl carbon center were found to favor tandem 1,2‐acyloxy migration/cyclopropanation followed by Cope rearrangement of the resulting cis‐3‐azabicyclo[3.1.0]hexane intermediate. On the other hand, substrates containing a terminal diene or starting materials in which the distal alkene moiety bears a phenyl substituent were observed to undergo competitive but reversible 1,3‐acyloxy migration prior to the nitrogen‐containing bicyclic ring formation. The delineated reaction mechanism also provides experimental evidence for the reversible interconversion between the oft‐proposed organogold intermediates obtained in this step of the tandem process.
Highly Enantioselective Catalytic System for Asymmetric Copolymerization of Carbon Dioxide and Cyclohexene Oxide
Authors: Hua Yuan‐Zhao , Lu Liu‐Jie , Huang Pei‐Jin , Wei Dong‐Hui , Tang Ming‐Sheng , Wang Min‐Can , Chang Jun‐Biao 
Published: August 2014

AbstractA new ligand can be easily prepared, and its intramolecular dinuclear zinc complexes act as a high performance catalyst for the asymmetric alternating copolymerization of cyclohexene oxide and CO2 under very mild conditions (1 atm CO2, room temperature), affording completely alternating polycarbonates with up to 93.8 % enantiomeric excess (ee) and 98 % yield. A high Mn value of 28 600 and a relatively narrow polydispersity (Mw/Mn ratio) of 1.43 were also achieved.
Thioetherification of Chloroheteroarenes: A Binuclear Catalyst Promotes Wide Scope and High Functional‐Group Tolerance
Authors: Platon Mélanie , Wijaya Novi , Rampazzi Vincent , Cui Luchao , Rousselin Yoann , Saeys Mark , Hierso Jean‐Cyrille 
Published: August 2014

AbstractA constrained binuclear palladium catalyst system affords selective thioetherification of a wide range of functionalized arenethiols with chloroheteroaromatic partners with the highest turnover numbers (TONs) reported to date and tolerates a large variety of reactive functions. The scope of this system includes the coupling of thiophenols with six‐ and five‐membered 2‐chloroheteroarenes (i.e., functionalized pyridine, pyrazine, quinoline, pyrimidine, furane, and thiazole) and 3‐bromoheteroarenes (i.e., pyridine and furane). Electron‐rich congested thiophenols and fluorinated thiophenols are also suitable partners. The coupling of unprotected amino‐2‐chloropyridines with thiophenol and the successful employment of synthetically valuable chlorothiophenols are described with the same catalyst system. DFT studies attribute the high performance of this binuclear palladium catalyst to the decreased stability of thiolate‐containing resting states. Palladium loading was as low as 0.2 mol %, which is important for industrial application and is a step forward in solving catalyst activation/deactivation problems.
Versatile CuI/Pd0 Dual Catalysis for the Synthesis of Quaternary α‐Allylated Carbonyl Compounds: Development, Mechanistic Investigations and Scope
Authors: Nahra Fady , Macé Yohan , Boreux Arnaud , Billard Francois , Riant Olivier 
Published: August 2014

AbstractWe report herein a versatile cooperative dual catalysis reaction based on a CuI/Pd0 system. Mechanistic investigation shows that every component plays a crucial role in determining the reaction outcome. The reaction is successfully extended to various substrates; such as α,β‐unsaturated ketones, malonates and coumarins. The strategy tolerates different substitution patterns and affords good yields for each family of substrates.
N‐Alkylacylamides in Thin Films Display Infrared Spectra of 310‐, α‐, and π‐Helices with Visible Static and Dynamic Growth Phases
Authors: Kosower Edward M. , Borz Galina 
Published: August 2014

AbstractA peptide model is a physical system containing a CONH group, the simplest being HCONHCH3, N‐methylformamide (NMF). We have discovered that NMF and N‐methylacetamide (NMA), which form hydrogen‐bonded oligomers in thin films on a planar AgX fiber, display infrared (IR) spectra with peaks like those of polypeptide helices. Structures can be assigned by their amide I maxima near 1672 (310), 1655 (310), 1653 (α), 1655 (π), and 1635 cm−1 (π), which are the first IR data for the π‐helix. Sharp peaks are an outcome of immobilization of polar species on the polar surface of silver halides. We report the first use of expanded thin‐film IR spectroscopy, in which plots of every spectrum over the amide I–II range show pauses or slow stages in the increase or decrease of absorption. These are identified as static phases followed by dynamic phases, with the incremental gain or loss of a helix turn. A general theory can be stated for such processes. Density functional calculations show that the NMA α‐helix pentamer (crystal structure geometry) is transformed into a π‐helix‐like form. For the first time, an entire sequence (310‐helix, α‐helix, π‐helix, quasiplanar species) of spectra has been recorded for NMA.
N‐Methyl‐trimethylacetamide in Thin Films Displays Infrared Spectra of π‐Helices, with Visible Static and Dynamic Growth Phases, and then a β‐Sheet
Authors: Kosower Edward M. , Borz Galina , Goldberg Israel , Ermakov Natalya 
Published: August 2014

AbstractThe simplest (minimal) peptide model is HCONHCH3. An increase in the π‐helix content with increased substitution in the acyl portion suggested the examination of N‐methyl‐trimethylacetamide) (NMT). NMT displays spectra, in which there is evolution of a set of helices defined by their amide I maxima near 1686 (310), 1655 (first π), and, most importantly, at 1637 cm−1 (π). Expanded thin‐film infrared spectroscopy (XTFIS) shows pauses or slow stages, which are identified as static phases followed by dynamic phases with the incremental gain or loss of a helix turn. In addition, absorbance at 1637 cm−1 suddenly increases at 82.1 s (30 % over 0.3 s), indicating a phase change and crystallization of the π‐helix, along with a coincidental decrease in the absorbance for the first π‐helix. A sharp peak occurs at the maximum of the phase change at 82.5 s, representing a pure NMT π‐helix. The spectra then undergo a decreasing general absorption loss over 150 s, with the π‐helix evolving further to an antiparallel β‐sheet fragment. The spectral quality arises from the immobilization of polar molecules on polar surfaces. The crystal structure is that of an antiparallel β‐sheet.
Theoretical Modeling of Low‐Energy Electronic Absorption Bands in Reduced Cobaloximes
Authors: Bhattacharjee Anirban , Chavarot‐Kerlidou Murielle , Dempsey Jillian L. , Gray Harry B. , Fujita Etsuko , Muckerman James T. , Fontecave Marc , Artero Vincent , Arantes Guilherme M. , Field Martin J. 
Published: August 2014

AbstractThe reduced CoI states of cobaloximes are powerful nucleophiles that play an important role in the hydrogen‐evolving catalytic activity of these species. In this work we analyze the low‐energy electronic absorption bands of two cobaloxime systems experimentally and use a variety of density functional theory and molecular orbital ab initio quantum chemical approaches. Overall we find a reasonable qualitative understanding of the electronic excitation spectra of these compounds but show that obtaining quantitative results remains a challenging task.
Synthesis of Urchin‐Like FeF2 Nanoarchitectures and Their Conversion into Three‐Dimensional Urchin‐Like Mesoporous α‐Fe2O3 Nanoarchitectures for Methane Activation
Authors: Dong Bing , Zhang Hengqiang , Kong Aiguo , Kong Yingying , Yang Fan , Shan Yongkui 
Published: August 2014

AbstractNovel urchin‐like FeF2 nanoarchitectures have been fabricated by an unconventional nonhomogeneous ionic liquid/diphenyl ether solvothermal method. Subsequent solid‐state thermal annealing was utilized to convert the FeF2 nanoarchitectures into 3D urchin‐like mesoporous α‐Fe2O3 nanoarchitectures. The reaction system and temperature played important roles in the morphology of FeF2 and the growth of the 3D urchin‐like α‐Fe2O3. A study of methane activation over the 3D urchin‐like mesoporous α‐Fe2O3 nanoarchitectures revealed that methane was activated and converted into carbon dioxide at a low temperature (230 °C). Compounds containing C–C bonds were produced at 600 °C. This 3D urchin‐like mesoporous α‐Fe2O3 shows excellent potential as a catalyst for methane conversion in the chemical industry.
Highly Enantioselective Construction of Polycyclic Spirooxindoles by Organocatalytic 1,3‐Dipolar Cycloaddition of 2‐Cyclohexenone Catalyzed by Proline‐Sulfonamide
Authors: Xiao Jun‐An , Liu Qi , Ren Ji‐Wei , Liu Jian , Carter Rich G. , Chen Xiao‐Qing , Yang Hua 
Published: August 2014

AbstractThe enantioselective 1,3‐dipolar cycloaddition of 2‐cyclohexene‐1‐one and azomethine ylides generated in situ from isatins and amino esters was developed by employing prolinosulfonamides as the catalyst. Consequently, novel polycyclic spirooxindole scaffolds with three contiguous stereocenters were prepared in high yield (up to 95 %) with excellent diastereo‐ (>20:1 dr) and enantioselectivity (up to 99 % ee).
Fast and versatile fabrication of PMMA microchip electrophoretic devices by laser engraving
Authors: Gabriel Ellen Flávia Moreira , Coltro Wendell Karlos Tomazelli , Garcia Carlos D. 
Published: August 2014

Electrophoresis 2014, 35, 2325–2332. DOI: 10.1002/elps.elps201300511In order to demonstrate the versatility of the proposed methodology, a PMMA substrate was engraved following the conditions described in our article (CO2 laser engraving, raster mode, 1200 dpi) and then imaged using a 3D microscope. We believe these two instruments are very good complements of the traditional instrumentation linked to the fabrication and characterization of microfluidic devices and could provide not only a simple way to produce devices but also a new way to see the surface of the features produced.
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QoS‐based power allocation for cognitive radios with AMC and ARQ in Nakagami‐m fading channels
Authors: Musavian Leila , Le‐Ngoc Tho 
Published: August 2014

AbstractThis paper presents power allocation schemes to maximize the effective capacity (EC) of a secondary user (SU) communications link using adaptive modulation and coding (AMC) in an underlay cognitive radio Nakagami‐m block‐fading environment to meet target quality‐of‐service (QoS) requirements in terms of delay‐outage probability and packet error rate constraints. The SU transmission parameters are chosen such that the primary user imposed interference power constraint (IPC) is satisfied. Three different types of IPCs, namely average interference power, peak interference power and interference power outage, are considered. For each IPC, the analytical solutions for choosing the AMC mode and power allocation in each fading block, and the corresponding SU achievable EC under given QoS requirements are derived. Furthermore, we investigate the performance of a hybrid automatic repeat request (ARQ)/AMC and obtain the closed‐form packet loss rate expression. Illustrative results show the effects of the IPC, fading duration and fading severeness on the SU achievable EC under given QoS requirements. It is shown that for loose delay‐outage requirements, average interference power and interference power outage constraints give higher SU EC than peak interference power constraint. However, for more stringent delay‐outage requirements, the SU achievable EC for the three IPC is significantly reduced. The results also indicate that ARQ is helpful to significantly reduce the packet loss rate for loose delay constraint. However, ARQ increases the delay and is not effective for stringent delay‐outage requirements. Copyright © 2014 John Wiley & Sons, Ltd.
Energy‐efficient opportunistic forwarding in multi‐hop cellular networks using device‐to‐device communications
Authors: Coll‐Perales B. , Gozalvez J. , Friderikos V. 
Published: August 2014

AbstractCellular networks face significant capacity, efficiency and quality challenges because of the exponential growth of cellular data traffic. Multi‐hop cellular networks (MCNs) have been proposed to address these challenges through the integration of cellular and device‐to‐device communications. This work investigates how the adoption and design of opportunistic store, carry and forward mechanisms in MCNs can help importantly decrease the energy consumption for delay tolerant traffic. To this aim, the study first derives an analytical framework to identify in two‐hop scenarios the optimum mobile relay location and the location from which the mobile relay should start forwarding the information to the cellular base station in order to minimise the overall energy consumption. The derived optimum configuration is then used as a benchmark for the proposal and design of a novel context‐based opportunistic MCN forwarding scheme that exploits context information provided at low cost by the cellular network. Numerical and simulation results demonstrate that the proposed context‐based opportunistic forwarding can achieve a performance close to that obtain with the optimum configuration and reduce the energy consumption by more than 90% compared with traditional single‐hop cellular communications. Copyright © 2014 John Wiley & Sons, Ltd.
A demand‐based spectrum orthogonalisation scheme for interference avoidance in LTE‐Advanced heterogeneous networks
Authors: Mohamad Maharum Siti M. , Fisal Norsheila , Lo Anthony , Ghafar Aimi S. A. , Saparudin Faiz Asraf , Katiran Norshidah 
Published: August 2014

AbstractSuccessful deployment of femtocells within a macrocell coverage area would be hindered if cross‐layer and co‐layer interference in such heterogeneous networks (HetNets) is not properly mitigated. Through spectrum management, cross‐layer interference between macrocell and femtocell network layers can be avoided by assigning the network layers with orthogonal spectrum bands. However, the orthogonal spectrum assignments in prior works are no longer effective because they may not guarantee the variation of users' traffic demand in HetNets to be satisfied all the time. Therefore, a centralised and dynamic orthogonal spectrum assignment called demand‐based spectrum orthogonalisation (DeBaSO) is proposed in this paper to address the interference issues in downlink of LTE‐Advanced HetNets. In our proposed scheme, the problem of orthogonal spectrum assignment is formulated with the objective to maximise the overall system throughput based on the requirement of physical spectral resources to satisfy the users' traffic demand. Additionally, the co‐layer interference among femtocells is avoided by grouping the adjacent femtocells into different femtocell clusters. To do so, typical model of spatial frequency reuse is exploited in this paper. In this way, femtocells that are grouped within the same cluster can universally reuse the assigned spectrum resource without creating co‐layer interference among them. Numerical results indicate that the proposed scheme achieves a remarkable performance in terms of overall system throughput and spectrum efficiency because the cross‐layer and co‐layer interference is entirely avoided. The achievements prove that DeBaSO scheme overcomes the limitations found in other orthogonal spectrum assignments, which were previously proposed in the literature. Copyright © 2014 John Wiley & Sons, Ltd.
Torii: multipath distributed Ethernet fabric protocol for data centres with zero‐loss path repair
Authors: Rojas Elisa , Ibanez Guillermo , Gimenez‐Guzman Jose Manuel , Rivera Diego , Azcorra Arturo 
Published: August 2014

AbstractThis paper describes and evaluates Torii, a layer 2 data centre network fabric protocol. The main features of Torii are being fully distributed, scalable, fault‐tolerant and with automatic setup. Torii is based on multiple, tree‐based, topological media access control addresses that are used for table‐free forwarding over multiple equal‐cost paths, and it is capable of rerouting frames around failed links on the fly without needing a central fabric manager for any function. To the best of our knowledge, it is the first protocol that does not require the exchange of periodic messages to work under normal conditions and to recover from link failures, as Torii exchanges messages just once. Moreover, another important characteristic of Torii is that it is compatible with a wide range of data centre topologies. Simulation results show an excellent distribution of traffic load and latencies, similar to the shortest path protocols. Copyright © 2014 John Wiley & Sons, Ltd.
Population‐Based Association and Gene by Environment Interactions in Genetic Analysis Workshop 18
Authors: Satten Glen A. , Biswas Swati , Papachristou Charalampos , Turkmen Asuman , König Inke R. 
Published: August 2014

ABSTRACTIn the past decade, genome‐wide association studies have been successful in identifying genetic loci that play a role in many complex diseases. Despite this, it has become clear that for many traits, investigation of single common variants does not give a complete picture of the genetic contribution to the phenotype. Therefore a number of new approaches are currently being investigated to further the search for susceptibility loci or regions. We summarize the contributions to Genetic Analysis Workshop 18 (GAW18) that concern this search using methods for population‐based association analysis. Many of the members of our GAW18 working group made use of data types that have only recently become available through the use of next‐generation sequencing technologies, with many focusing on the investigation of rare variants instead of or in combination with common variants. Some contributors used a haplotype‐based approach, which to date has been used relatively infrequently but may become more important for analyzing rare variant association data. Others analyzed gene‐gene or gene‐environment interactions, where novel statistical approaches were needed to make the best use of the available information without requiring an excessive computational burden. GAW18 provided participants with the chance to make use of state‐of‐the‐art data, statistical techniques, and technology. We report here some of the experiences and conclusions that were reached by workshop participants who analyzed the GAW18 data as a population‐based association study.