bluuebunny/crossref_metadata_2025_split huggingface dataset:
Transition Metal‐Free Intermolecular α‐CH Amination of Ethers at Room Temperature
Authors: Buslov Ivan , Hu Xile 
Published: September 2014

AbstractWe describe a new method for the intermolecular amination of the α‐CH bonds of ethers. A hypervalent iodine reagent was used as oxidant to enable the amination of cyclic and acyclic alkyl ethers with a wide range of amides, imides, and amines. The amination occurred at room temperature and without a transition metal catalyst. The method could be used to synthesize the anti‐cancer prodrug Tegafur and its analogues.magnified image
Aquaporin expression profiles in normal sinonasal mucosa and chronic rhinosinusitis
Authors: Frauenfelder Claire , Woods Charmaine , Hussey Damian , Ooi Eng , Klebe Sonja , Carney A. Simon 
Published: September 2014

BackgroundThickened secretions, mucosal edema, and polyp formation are pathological features in chronic rhinosinusitis (CRS) that could theoretically be caused by aberrant water flow through sinonasal mucosa. Aquaporins (AQPs) are a family of proteins with roles in water transport, with tissue‐specific expression profiles. This study aims to determine if AQP expression in sinonasal mucosa is different between normal controls and patients with CRS, either with (CRSwNP) or without (CRSsNP) nasal polyps.MethodsDuring endoscopic sinus surgery or transsphenoidal surgery, sinonasal tissue was collected and classified as CRSwNP (n = 13), CRSsNP (n = 10), or normal (n = 10). Messenger RNA (mRNA) expression of human AQP0 to AQP12b was determined using quantitative real‐time polymerase chain reaction (qRT‐PCR). Cellular localization of AQP1, AQP3, AQP4, AQP5, AQP7, and AQP11 was determined by immunohistochemistry.ResultsmRNA of AQP0 to AQP11 was identified in all samples. AQP12b mRNA was not detected. Significant differences in the mRNA expression levels of AQP4 and AQP11 were identified between normal and CRSwNP patients (p < 0.05). Differences in the cellular localization of AQPs were observed in both CRSsNP and CRSwNP patients vs normal controls. More intense localization to the cell cytoplasm was observed for AQP5 in glandular epithelium (CRSwNP; p < 0.05) and surface epithelium (CRSsNP; p < 0.05), and AQP4 in glandular epithelium (CRSsNP; p < 0.05).ConclusionThis study characterized AQP mRNA expression and protein localization in normal human sinonasal tissue. Significant differences in mRNA expression were found for AQP4 and AQP11 in CRSwNP and differences in protein localization patterns of AQP4 and AQP5 were identified in both types of CRS.
Photocatalytic Generation of N‐Centered Hydrazonyl Radicals:  A Strategy for Hydroamination of β,γ‐Unsaturated Hydrazones
Authors: Hu Xiao‐Qiang , Chen Jia‐Rong , Wei Qiang , Liu Feng‐Lei , Deng Qiao‐Hui , Beauchemin André M. , Xiao Wen‐Jing 
Published: September 2014

AbstractA visible‐light photocatalytic generation of N‐centered hydrazonyl radicals has been accomplished for the first time. This approach allows efficient intramolecular addition of hydrazonyl radical to terminal alkenes, thus providing hydroamination and oxyamination products in good yields. Importantly, the protocol involves deprotonation of an NH bond and photocatalytic oxidation to an N‐centered radical, thus obviating the need to prepare photolabile amine precursors or the stoichiometric use of oxidizing reagents.
Enantioselective Synthesis of a Chiral Coordination Polymer with Circularly Polarized Visible Laser
Authors: Wu Shu‐Ting , Cai Zhen‐Wen , Ye Qiao‐Yan , Weng Chen‐Hao , Huang Xi‐He , Hu Xiao‐Lin , Huang Chang‐Cang , Zhuang Nai‐Feng 
Published: September 2014

AbstractCircular dichroism is known to be the feature of a chiral agent which has inspired scientist to study the interesting phenomena of circularly polarized light (CPL) modulated molecular chirality. Although several organic molecules or assemblies have been found to be CPL‐responsive, the influence of CPL on the assembly of chiral coordination compounds remains unknown. Herein, a chiral coordination polymer, which is constructed from achiral agents, was used to study the CPL‐induced enantioselective synthesis. By irradiation with either left‐handed or right‐handed CPL during the reaction and crystallization, enantiomeric excesses of the crystalline product were obtained. Left‐handed CPL resulted in crystals with a left‐handed helical structure, and right‐handed CPL led to crystals with a right‐handed helical structure. It is exciting that the absolute asymmetric synthesis of a chiral coordination polymer could be enantioselective when using CPL, and provides a strategy for the control of the chirality of chiral coordination polymers.
Synthesis of Extended π‐Systems through C–H Activation
Authors: Segawa Yasutomo , Maekawa Takehisa , Itami Kenichiro 
Published: September 2014

AbstractActivation of aromatic CH bonds by a transition metal catalyst has received significant attention in the synthetic chemistry community. In recent years, rapid and site‐selective extension of π‐electron systems by C–H activation has emerged as an ideal methodology for preparing organic materials with extended π‐systems. This Review focuses on recently reported π‐extending C–H activation reactions directed toward new optoelectronic conjugated materials.
Formation and Rearrangement of Homoserine Depsipeptides and Depsiproteins in the α‐Ketoacid–Hydroxylamine Ligation with 5‐Oxaproline
Authors: Wucherpfennig Thomas G. , Rohrbacher Florian , Pattabiraman Vijaya R. , Bode Jeffrey W. 
Published: September 2014

AbstractThe primary products of the chemical ligation of α‐ketoacids and 5‐oxaproline peptides are esters, rather than the previously reported amides. The depsipeptide product rapidly rearranges to the amide in basic buffers. The formation of esters sheds light on possible mechanisms for the type II KAHA ligations and opens an avenue for the chemical synthesis of depsiproteins.
Tuning the Selectivity of Photocatalytic Synthetic Reactions Using Modified TiO2 Nanotubes
Authors: Tripathy Jyotsna , Lee Kiyoung , Schmuki Patrik 
Published: September 2014

AbstractDifferently modified TiO2 nanotubes were used to achieve a drastic change in the selectivity of a photocatalytic reaction. For the photocatalytic oxidation of toluene, depending on the electronic properties of TiO2 (anatase, rutile, Ru‐doped), a strong change in the main reaction product (namely benzoic acid versus benzaldehyde) can be achieved, and certain undesired reaction pathways can be completely shut down.
Traceless Preparation of C‐Terminal α‐Ketoacids for Chemical Protein Synthesis by α‐Ketoacid–Hydroxylamine Ligation: Synthesis of SUMO2/3
Authors: Wucherpfennig Thomas G. , Pattabiraman Vijaya R. , Limberg Felix R. P. , Ruiz‐Rodríguez Javier , Bode Jeffrey W. 
Published: September 2014

AbstractA novel protecting group for enantiopure α‐ketoacids delivers C‐terminal peptide α‐ketoacids directly upon resin cleavage and allows the inclusion of all canonical amino acids, including cysteine and methionine. By using this approach, SUMO2 and SUMO3 proteins were prepared by KAHA ligation with 5‐oxaproline. The synthetic proteins containing homoserine residues were recognized by and conjugated to RanGAP1 by SUMOylation enzymes.
Semisynthesis of Biologically Active Glycoforms of the Human Cytokine Interleukin 6
Authors: Reif Andreas , Siebenhaar Sebastian , Tröster Andrea , Schmälzlein Marina , Lechner Carolin , Velisetty Phanindra , Gottwald Karen , Pöhner Claudia , Boos Irene , Schubert Volker , Rose‐John Stefan , Unverzagt Carlo 
Published: September 2014

AbstractHuman interleukin 6 (IL‐6) is a potent cytokine with immunomodulatory properties. As the influence of N‐glycosylation on the in vivo activities of IL‐6 could not be elucidated so far, a semisynthesis of homogeneous glycoforms of IL‐6 was established by sequential native chemical ligation. The four cysteines of IL‐6 are convenient for ligations and require only the short synthetic glycopeptide 43–48. The Cys‐peptide 49–183 could be obtained recombinantly by cleavage of a SUMO tag. The fragment 1–42 was accessible by the simultaneous cleavage of two inteins, leading to the 1–42 thioester with the native N‐terminus. Ligation and refolding studies showed that the inherently labile AspPro bond 139–140 was detrimental for the sequential C‐ to N‐terminal ligation. A reversed ligation sequence using glycopeptide hydrazides gave full‐length IL‐6 glycoproteins, which showed full bioactivity after efficient refolding and purification.
Carbon Dioxide Reduction to Methylamines under Metal‐Free Conditions
Authors: Blondiaux Enguerrand , Pouessel Jacky , Cantat Thibault 
Published: September 2014

AbstractThe first metal‐free catalysts are reported for the methylation of amines with carbon dioxide. Proazaphosphatrane superbases prove to be highly active catalysts in the reductive functionalization of CO2, in the presence of hydroboranes. The new methodology enables the methylation of NH bonds in a wide variety of amines, including secondary amines, with increased chemoselectivity.
Synergistic effects of N, N′‐bis (benzoyl) sebacic acid dihydrazide and talc on the physical and mechanical behaviors of poly(l‐latic acid)
Authors: Xiao Hongqin , Guo Dan , Bao Jianjun 
Published: September 2014

ABSTRACTThe important practical problem of poor heat stability of poly(l‐lactic acid) (PLLA) is addressed by the addition of N, N′‐bis (benzoyl) sebacic acid dihydrazide (BSAD) and talc as a nucleating agent system. The idea of incorporating talc into the PLLA/BSAD composites is that talc can provide supplementary nucleation effect with very small amount of BSAD (0.2 wt %) and therefore can improve the heat deflection resistance of PLLA materials. Effects of BSAD/talc on morphology, crystallization behavior, heat resistance, and mechanical properties of PLLA/BSAD/talc were investigated after annealing processes. The results indicated that the BSAD/talc system increased the crystallinity from 6.0% of pure PLLA to a maximum 42.9% by the synergistic effects of BSAD and talc increasing the growth of spherulites and nucleation density, respectively. After annealing at different temperatures, the heat deflection temperature (HDT) of PLLA was improved dramatically due to synergistic effects of BSAD/talc between restricted chain movement and acceleration of crystallization. At high temperature (above Tg), the thermo‐mechanical properties of PLLA is mainly determined by the crystallinity and the reinforcement effect of talc acted as a filler. Moreover, effects of BSAD/talc on mechanical properties were discussed. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41454.
Efficient Synthesis of Frutinone A and Its Derivatives through Palladium‐Catalyzed CH Activation/Carbonylation
Authors: Shin Yongje , Yoo Changho , Moon Youngtaek , Lee Yunho , Hong Sungwoo 
Published: September 2014

AbstractFrutinone A, a biologically active ingredient of an antimicrobial herbal extract, demonstrates potent inhibitory activity towards the CYP1A2 enzyme. A three‐step total synthesis of frutinone A with an overall yield of 44 % is presented. The construction of the chromone‐annelated coumarin core was achieved through palladium‐catalyzed CH carbonylation of 2‐phenolchromones. The straightforward synthetic route allowed facile substitutions around the frutinone A core and thus rapid exploration of the structure–activity relationship (SAR) profile of the derivatives. The inhibitory activity of the synthesized frutinone A derivatives were determined for CYP1A2, and ten compounds exhibited one‐to‐two digit nanomolar inhibitory activity towards the CYP1A2 enzyme.
The oscillation of the perturbation potential energy between the extratropics and tropics in boreal winter
Authors: Wang Lei , Li Jianping , Wang Zhanggui , Li Yanjie , Zheng Fei 
Published: September 2014

AbstractCorrelation analyses reveal that the perturbation potential energy (PPE) in the extratropics and tropics in boreal winters undergoes out‐of‐phase oscillations (PPE1 extratropics–tropics oscillation, PETO). PETO is closely related to both El Niño‐Southern Oscillation (ENSO) and kinetic energy, furthermore, PETO tends to dominate over the extratropics while ENSO is more important over the tropics. In the Northern (Southern) Hemisphere, positive PETO phases tend to strengthen (weaken) Hadley circulation and to weaken (strengthen) an expanded Ferrel circulation, resulting in equatorward shift of the subtropical jet streams. In addition, precipitation is enhanced in regions of ascending vertical motion, and warmer temperatures are observed in the tropics except over the western Pacific.
Degradable Hybrid Materials Based on Cationic Acylhydrazone Dynamic Covalent Polymers Promote DNA Complexation through Multivalent Interactions
Authors: Bouillon Camille , Paolantoni Delphine , Rote Jennifer C. , Bessin Yannick , Peterson Larryn W. , Dumy Pascal , Ulrich Sébastien 
Published: September 2014

AbstractThe design of smart nonviral vectors for gene delivery is of prime importance for the successful implementation of gene therapies. In particular, degradable analogues of macromolecules represent promising targets as they would combine the multivalent presentation of multiple binding units that is necessary for achieving effective complexation of therapeutic oligonucleotides with the controlled degradation of the vector that would in turn trigger drug release. Toward this end, we have designed and synthesized hybrid polyacylhydrazone‐based dynamic materials that combine bis‐functionalized cationic monomers with ethylene oxide containing monomers. Polymer formation was characterized by 1H and DOSY NMR spectroscopy and was found to take place at high concentration, whereas macrocycles were predominantly formed at low concentration. HPLC monitoring of solutions of these materials in aqueous buffers at pH values ranging from 5.0 to 7.0 revealed their acid‐catalyzed degradation. An ethidium bromide displacement assay and gel electrophoresis clearly demonstrated that, despite being dynamic, these materials are capable of effectively complexing dsDNA in aqueous buffer and biological serum at N/P ratios comparable to polyethyleneimine polymers. The self‐assembly of dynamic covalent polymers through the incorporation of a reversible covalent bond within their main chain is therefore a promising strategy for generating degradable materials that are capable of establishing multivalent interactions and effectively complexing dsDNA in biological media.
Exchange‐Coupled fct‐FePd/α‐Fe Nanocomposite Magnets Converted from Pd/Fe3O4 Core/Shell Nanoparticles
Authors: Liu Fei , Dong Yunhe , Yang Wenlong , Yu Jing , Xu Zhichuan , Hou Yanglong 
Published: September 2014

AbstractWe report the controlled synthesis of exchange‐coupled face‐centered tetragonal (fct) FePd/α‐Fe nanocomposite magnets with variable Fe concentration. The composite was converted from Pd/Fe3O4 core/shell nanoparticles through a high‐temperature annealing process in a reducing atmosphere. The shell thickness of core/shell Pd/Fe3O4 nanoparticles could be readily tuned, and subsequently the concentration of Fe in nanocomposite magnets was controlled. Upon annealing reduction, the hard magnetic fct‐FePd phase was formed by the interdiffusion between reduced α‐Fe and face‐centered cubic (fcc) Pd, whereas the excessive α‐Fe remained around the fct‐FePd grains, realizing exchange coupling between the soft magnetic α‐Fe and hard magnetic fct‐FePd phases. Magnetic measurements showed variation in the magnetic properties of the nanocomposite magnets with different compositions, indicating distinct exchange coupling at the interfaces. The coercivity of the exchange‐coupled nanocomposites could be tuned from 0.7 to 2.8 kOe and the saturation magnetization could be controlled from 93 to 160 emu g−1. This work provides a bottom‐up approach using exchange‐coupled nanocomposites for engineering advanced permanent magnets with controllable magnetic properties.
Methanol production by bi‐reforming
Authors: Santos Bruno A. V. , Loureiro José M. , Ribeiro Ana M. , Rodrigues Alírio E. , Cunha Adelino F. 
Published: September 2014

AbstractPopulation growth and emerging economies have as consequence increasing energy demands associated with fossil fuel depletion and environmental impacts. A new philosophy emerges: the concept of green chemistry. Carbon dioxide, a well‐known greenhouse gas, is a source for the production of fine chemicals and fuels such as methanol. It appears in abundance due to anthropogenic human activities. Nowadays, methanol is typically produced from synthesis‐gas which requires conventional fossil fuels; however, the availability of these fuels is limited. As an alternative, the vent streams of steam reforming units, which are rich in carbon dioxide and steam, can be used together with methane (natural gas) in a bi‐reforming process for methanol synthesis. The essential idea is that carbon dioxide and water are recycled like in a synthetic photosynthesis process.
Synaptic connections of first‐stage visual neurons in the locust Schistocerca gregaria extend evolution of tetrad synapses back 200 million years
Authors: Wernitznig Stefan , Rind Frances Claire , Pölt Peter , Zankel Armin , Pritz Elisabeth , Kolb Dagmar , Bock Elisabeth , Leitinger Gerd 
Published: September 2014

ABSTRACTThe small size of some insects, and the crystalline regularity of their eyes, have made them ideal for large‐scale reconstructions of visual circuits. In phylogenetically recent muscomorph flies, like Drosophila, precisely coordinated output to different motion‐processing pathways is delivered by photoreceptors (R cells), targeting four different postsynaptic cells at each synapse (tetrad). Tetrads were linked to the evolution of aerial agility. To reconstruct circuits for vision in the larger brain of a locust, a phylogenetically old, flying insect, we adapted serial block‐face scanning electron microscopy (SBEM). Locust lamina monopolar cells, L1 and L2, were the main targets of the R cell pathway, L1 and L2 each fed a different circuit, only L1 providing feedback onto R cells. Unexpectedly, 40% of all locust R cell synapses onto both L1 and L2 were tetrads, revealing the emergence of tetrads in an arthropod group present 200 million years before muscomorph flies appeared, coinciding with the early evolution of flight. J. Comp. Neurol. 523:298–312, 2015. © 2014 Wiley Periodicals, Inc.
An optical model relating (L*a*b*) values for a scattering surface covered with a scattering layer to (L*a*b*) values for the uncovered surface and its application to tooth colour
Authors: Battersby Stephen J. , Battersby Paul D. 
Published: September 2014

AbstractThe appearance of human dentition is important both psychologically and commercially. Many people perceive the lightness and chromaticity of their teeth as key factors in their overall appearance leading to large businesses in materials for colour‐matched fillings and crowns and in tooth whitening products. The human eye is very sensitive to small colour differences, recognizing a row of highly colour‐matched crowns as unnatural yet seeing excessive colour variation or darkness as unattractive. One cause of tooth discolouration is a darkening of the dentine, visible through the enamel. This has lead the authors to develop a model capable of relating (
) measurements on a scattering surface, in our case dentine, to (
) measurements when overlaid by a translucent scattering layer, in our case tooth enamel. The model can be used when any scattering layer is superimposed on a coloured surface. In contrast to existing models, no spectral measurements are necessary allowing the use of colourimeters rather than spectrophotometers. However, there are limitations on the degree of colour saturation for both the coloured surface and the scattering layer as the model uses an approximation valid only for weakly saturated colours. As neither the enamel nor the dentine have strongly saturated colouration, the limitation is entirely acceptable for our work. The use of (
) measurements directly rather than having to measure the spectrum of reflected light is of practical importance as such measurements in a dental surgery are impossible in all but exceptional cases whilst (
) measurements in the surgery are routine. © 2014 Wiley Periodicals, Inc. Col Res Appl, 40, 504–517, 2015
Structure–Activity Relationships of Glycogen Phosphorylase Inhibitor FR258900 and Its Analogues: A Combined Synthetic, Enzyme Kinetics, and Computational Study
Authors: Juhász László , Varga Gergely , Sztankovics Andrea , Béke Ferenc , Docsa Tibor , Kiss‐Szikszai Attila , Gergely Pál , Kóňa Juraj , Tvaroška Igor , Somsák László 
Published: September 2014

AbstractInvited for this month’s cover are a group of collaborators from the University of Debrecen (L. Somsák and P. Gergely) and the Institute of Chemistry of the Slovak Academy of Sciences (I. Tvaroška). The cover picture shows the natural product FR258900, some synthetic analogues, and the binding of the most active inhibitor to the allosteric site of the enzyme. Read the full text of the article at 10.1002/cplu.201402181
An initial evaluation of drone‐based monitoring of boulder beaches in Galicia, north‐western Spain
Authors: Pérez‐Alberti Augusto , Trenhaile Alan S. 
Published: September 2014

ABSTRACTLow altitude flights by a micro‐drone were made in 2012 and 2013 over two boulder beaches in north‐western Spain. Geographical information system software was used to map the data. Boulder outlines from the first flight were recorded on 4796 clasts at Laxe Brava and 2508 clasts at Oia. Changes in location were identified by overlaying these outlines on the 2013 images. About 17.5% of the boulders (mean surface area 0.32 m2) moved at Laxe Brava and about 53% (mean surface area 0.23 m2) at Oia. Most movement on both beaches was between the mid‐tide to about 2 m above the high tidal level. The location and elevation of the highest points were also recorded on the 2012 images on 4093 boulders at Laxe Brava and 3324 boulders at Oia. These elevations were compared with the elevations at the same locations in 2013. The occurrence and scale of the elevational changes were generally consistent with changes in the boulder outlines. The study confirmed that boulder beaches can be cheaply and effectively monitored using high resolution, micro‐drone technology. Copyright © 2014 John Wiley & Sons, Ltd.
Over the Hedge: Do Exporters Practice Selective Hedging?
Authors: Fabling Richard , Grimes Arthur 
Published: September 2014

AbstractWhat determines exporters’ exchange rate hedging decisions and do exporters attempt to “time the market?” We use a unique longitudinal dataset on firm exports to find the determinants of exporters’ currency hedging choices. Determinants include financial fragility, prior hedging experience, and natural hedge opportunities. We also find that firms alter their hedging ratios when the currency has recently trended in one direction. This behavior is ubiquitous for all but large firms and for all times other than when the exchange rate is near its extreme historical values. These results are consistent with most firms exhibiting (sub‐optimal) selective hedging behavior. © 2014 Wiley Periodicals, Inc. Jrl Fut Mark 35:321–338, 2015
Business Strategies: Increasing Brand Trust Among Utility Customers Lowers Costs and Turnover
Authors: Oberle Chris 
Published: September 2014

AbstractInteractions between utilities and customers have evolved over time from those that were once largely transactional and service‐based to those that are now initiative‐ and relationship‐oriented. This migration makes it clear that new tools for measuring the full strength of a utility's bond with customers are needed. Accordingly, research recently completed by Market Strategies International indicates that in addition to delivering on traditional operational satisfaction and product experience, utilities must deliver on a third factor—brand trust—if they are to develop strong and engaged relationships with their customers.