bluuebunny/crossref_metadata_2025_split huggingface dataset:
In situ measurements of polarization properties of snow surface under the Brewster geometry in Hokkaido, Japan, and northwest Greenland ice sheet
Authors: Tanikawa Tomonori , Hori Masahiro , Aoki Teruo , Hachikubo Akihiro , Kuchiki Katsuyuki , Niwano Masashi , Matoba Sumito , Yamaguchi Satoru , Stamnes Knut 
Published: November 2014

AbstractGround‐based measurements of spectral degree of linear polarization (DLP) of various snow types were made during intensive field campaigns in a snowfield in Hokkaido, Japan, and on the northwest Greenland ice sheet in 2012. Spectral measurements were conducted under the solar zenith angle of approximately the Brewster angle in order to quantify the polarization properties of light reflected from snow. We obtained spectral DLPs for five different snow types in both field campaigns including precipitation particles, needles, surface hoar, melt forms, and melt freeze crust covering the snow surface. The measurements showed that in the visible region the spectral dependence of the DLP was small while in the near infrared region it increased with increasing snow grain size with some distinct local peaks. The angular dependence indicated that the DLP exhibited small angular dependence in the visible region while in the near‐infrared region it exhibited large and broad peaks in the forward direction. Especially for the melt‐freeze crust, the DLP approached 1.0 at wavelengths close to λ = 1.5 and 2.0 μm. These features can be explained by (1) the relative contribution of surface versus volume scattering to the reflected light, (2) the incident angle (solar zenith angle) of approximately the Brewster angle, and (3) the ratio between direct and diffuse components of the solar radiation incident on the snow surface. The spectral DLP was found to be quiet sensitive to the incident solar radiation and solar elevation as well as snow optical properties. Comparison between the spectral DLP and snow grain size obtained by snow pit work shows that the DLP for λ > 1.5 μm was very sensitive to large snow grains close to the surface. This finding suggests that polarization measurements obtained from airborne/satellite polarimeters will be useful for surface snow grain size retrievals and help improve the accuracy of such retrievals based on the intensity‐only measurements, especially for the large snow grain sizes.
Constraints on abundance, composition, and nature of X‐ray amorphous components of soils and rocks at Gale crater, Mars
Authors: Dehouck Erwin , McLennan Scott M. , Meslin Pierre‐Yves , Cousin Agnès 
Published: November 2014

AbstractX‐ray diffraction patterns of the three samples analyzed by Curiosity's Chemistry and Mineralogy (CheMin) instrument during the first year of the Mars Science Laboratory mission—the Rocknest sand, and the John Klein and Cumberland drill fines, both extracted from the Sheepbed mudstone—show evidence for a significant amorphous component of unclear origin. We developed a mass balance calculation program that determines the range of possible chemical compositions of the crystalline and amorphous components of these samples within the uncertainties of mineral abundances derived from CheMin data. In turn, the chemistry constrains the minimum abundance of amorphous component required to have realistic compositions (all oxides ≥ 0 wt %): 21–22 wt % for Rocknest and 15–20 wt % for Cumberland, in good agreement with estimates derived from the diffraction patterns (~27 and ~31 wt %, respectively). Despite obvious differences between the Rocknest sand and the Sheepbed mudstone, the amorphous components of the two sites are chemically very similar, having comparable concentrations of SiO2, TiO2, Al2O3, Cr2O3, FeOT, CaO, Na2O, K2O, and P2O5. MgO tends to be lower in Rocknest, although it may also be comparable between the two samples depending on the exact composition of the smectite in Sheepbed. The only unambiguous difference is the SO3 content, which is always higher in Rocknest. The observed similarity suggests that the two amorphous components share a common origin or formation process. The individual phases possibly present within the amorphous components include: volcanic (or impact) glass, hisingerite (or silica + ferrihydrite), amorphous sulfates (or adsorbed SO42−), and nanophase ferric oxides.
Carbocations as Lewis Acid Catalysts: Reactivity and Scope
Authors: Bah Juho , Naidu Veluru Ramesh , Teske Johannes , Franzén Johan 
Published: November 2014

AbstractOne class of potential Lewis acids that has received negligible attention as a catalyst is the carbocation. Here we show the potential of triarylmethylium ions as highly powerful Lewis acid catalysts for organic reactions. The Lewis acidity of the triarylmethylium ion can be easily tuned by variation of the electronic properties of the aromatic rings and the catalytic activity of the carbocation is shown to correlate directly to the level of stabilization of the empty pC‐orbital at the cationic carbon. The versatility of triarylmethylium ions as efficient Lewis acid catalysts for organic reactions is demonstrated in Diels–Alder, aza‐Diels–Alder, conjugate addition, halogenation, epoxide rearrangement and intramolecular hetro‐ene reactions.magnified image
A Practical Aryl Unit for Azlactone Dynamic Kinetic Resolution: Orthogonally Protected Products and A Ligation‐Inspired Coupling Process
Authors: Tallon Sean , Manoni Francesco , Connon Stephen J. 
Published: November 2014

AbstractThe first strategy for bringing about enantioselective azlactone dynamic kinetic resolution to generate orthogonally protected amino acids has been developed. In the presence of a C2‐symmetric squaramide‐based catalyst, benzyl alcohol reacts with novel yet readily prepared tetrachloroisopropoxycarbonyl‐substituted azlactones to generate trapped phthalimide products of significant synthetic interest with excellent enantiocontrol. These materials are masked amino acids which are demonstrably orthogonally protected: cleavage of the phthalimide can be achieved in the presence of the ester and vice versa. This process could be utilized to bring about a highly stereoselective ligation‐type coupling of protected serines (at stoichiometric loadings) with racemic azlactones derived from both natural and abiotic amino acids. After deprotection, a subsequent base‐mediated O→N acyl transfer occurs to form a dipeptide.
Catalytic Activation of a Solid Oxide in Electronic Contact With Gold Nanoparticles
Authors: Behl Mayank , Jain Prashant K. 
Published: November 2014

AbstractAlthough inert in its bulk form, nanostructured gold supported on oxides has been found to be catalytically active. In many cases, the oxide promotes the activity of Au. It is now shown that in turn, nanoscale Au particles can chemically activate the solid oxide. Specifically, it was discovered that 4 nm Au nanoparticles deposited on zinc oxide catalyze the transformation of the oxide into the sulfide in the presence of an organosulfur species. Contact of the oxide with Au nanoparticles lowers the activation barrier for the solid‐state reaction by approximately 20 kJ mol−1, allowing the reaction to be achieved closer to ambient temperatures. Electron transfer from oxygen vacancies to Au nanoparticles is proposed to generate acidic sites on the surface of the zinc oxide, resulting in the enhanced reactivity of the oxide. Knowledge of such electronic interactions between the noble metal and oxide can be exploited for engineering reactive heterostructures for low‐temperature pollutant sorption and hydrocarbon processing.
Half‐Metallicity in Single‐Layered Manganese Dioxide Nanosheets by Defect Engineering
Authors: Wang Hui , Zhang Jiajia , Hang Xudong , Zhang Xiaodong , Xie Junfeng , Pan Bicai , Xie Yi 
Published: November 2014

AbstractDefect engineering is considered as one of the most efficient strategies to regulate the electronic structure of materials and involves the manipulation of the types, concentrations, and spatial distributions of defects, resulting in unprecedented properties. It is shown that a single‐layered MnO2 nanosheet with vacancies is a robust half‐metal, which was confirmed by theoretical calculations, whereas vacancy‐free single‐layered MnO2 is a typical semiconductor. The half‐metallicity of the single‐layered MnO2 nanosheet can be observed for a wide range of vacancy concentrations and even in the co‐presence of Mn and O vacancies. This work enables the development of half‐metals by defect engineering of well‐established low‐dimensional materials, which may be used for the design of next‐generation paper‐like spintronics.
Oil/Water Separation with Selective Superantiwetting/Superwetting Surface Materials
Authors: Chu Zonglin , Feng Yujun , Seeger Stefan 
Published: November 2014

AbstractThe separation of oil from oily water is an important pursuit because of increasing worldwide oil pollution. Separation by the use of materials with selective oil/water absorption is a relatively recent area of development, yet highly promising. Owing to their selective superantiwetting/superwetting properties towards water and oil, superhydrophobic/superoleophilic surfaces and underwater superoleophobic surfaces have been developed for the separation of oil/water‐free mixtures and emulsions. In this Review, after a short introduction to oil/water separation, we describe the principles of materials with selective oil/water absorption and outline recent advances in oil/water separation with superwetting/superantiwetting materials, including their design, their fabrication, and models of experimental setups. Finally, we discuss the current state of this new field and point out the remaining problems and future challenges.
Solution‐Grown Organic Single‐Crystalline Donor–Acceptor Heterojunctions for Photovoltaics
Authors: Li Hanying , Fan Congcheng , Fu Weifei , Xin Huolin L. , Chen Hongzheng 
Published: November 2014

AbstractOrganic single crystals are ideal candidates for high‐performance photovoltaics due to their high charge mobility and long exciton diffusion length; however, they have not been largely considered for photovoltaics due to the practical difficulty in making a heterojunction between donor and acceptor single crystals. Here, we demonstrate that extended single‐crystalline heterojunctions with a consistent donor‐top and acceptor‐bottom structure throughout the substrate can be simply obtained from a mixed solution of C60 (acceptor) and 3,6‐bis(5‐(4‐n‐butylphenyl)thiophene‐2‐yl)‐2,5‐bis(2‐ethylhexyl)pyrrolo[3,4‐c]pyrrole‐1,4‐dione (donor). 46 photovoltaic devices were studied with the power conversion efficiency of (0.255±0.095) % under 1 sun, which is significantly higher than the previously reported value for a vapor‐grown organic single‐crystalline donor–acceptor heterojunction (0.007 %). As such, this work opens a practical avenue for the study of organic photovoltaics based on single crystals.
Metal Dendrimers: Synthesis of Hierarchically Stellated Nanocrystals by Sequential Seed‐Directed Overgrowth
Authors: Weiner Rebecca G. , Skrabalak Sara E. 
Published: November 2014

AbstractHierarchically organized structures are prevalent in nature, where such features account for the adhesion properties of gecko feet and the brilliant color variation of butterfly wings. Achieving artificial structures with multiscale features is of interest for metamaterials and biomimetic applications. However, the fabrication of such structures relies heavily on lithographic approaches, although self‐assembly routes to superstructures are promising. Sequential seed‐directed overgrowth is now demonstrated as a route to metal dendrimers, which are hierarchically branched nanocrystals (NCs) with a three‐dimensional order analogous to that of molecular dendrimers. This method was applied to a model Au/Pd NC system; in general, the principle of sequential seed‐directed overgrowth should enable the synthesis of new hierarchical inorganic structures with high symmetry.
Gold‐Catalyzed Oxidative Ring Expansion of 2‐Alkynyl‐1,2‐Dihydropyridines or ‐quinolines: Highly Efficient Synthesis of Functionalized Azepine or Benzazepine Scaffolds
Authors: Chen Ming , Chen Yifeng , Sun Ning , Zhao Jidong , Liu Yuanhong , Li Yuxue 
Published: November 2014

AbstractA gold‐catalyzed highly regio‐ and chemoselective oxidative ring expansion of 2‐alkynyl‐1,2‐dihydropyridines and its analogues using pyridine‐N‐oxide as the oxidant has been developed. Ring expansion proceeds through exclusive 1,2‐migration of a vinyl or phenyl group, whereas no 1,2‐H and 1,2‐N migration take place. The reaction provides an efficient and attractive route to various types of medium‐sized azepine derivatives in generally high to excellent yields with a broad functional group tolerance. DFT studies indicate that the reaction proceeds through the formation of a cyclopropyl gold intermediate, and no gold carbene species is involved.
Adsorption isotherms, kinetic, and desorption studies on removal of toxic metal ions from aqueous solutions by polymeric adsorbent
Authors: Samadi Naser , Hasanzadeh Reza , Rasad Mohamad 
Published: November 2014

ABSTRACTAdsorption of Cd(II), Co(II), and Ni(II) on aminopyridine modified poly(styrene‐alt‐maleic anhydride) crosslinked by 1,2‐diaminoethane as an ion exchange resin has been investigated in aqueous solution. Adsorption behavior of these metal ions on the resin was studied by varying the parameters such as pH (2–6), adsorbent dose (0–4.0 g/L), contact time (0–240 min), and metal ions concentration (20–300 mg/L). Adsorption percentage was increased by increasing each of these parameters. The isotherm models such as: Langmuir, Freundlich, Temkin, and Dubinin–Radushkevich were used to describe adsorption equilibrium. The results showed that the best fit was achieved with the Langmuir isotherm equation, yielding maximum adsorption capacities of 81.30, 49.02, and 76.92 mg/g for Cd(II), Co(II), and Ni(II), respectively. The pseudo‐first‐order, pseudo‐second‐order, and intra‐particle diffusion kinetics equations were used for modeling of adsorption data and it was shown that pseudo‐second‐order kinetic equation could best describe the adsorption kinetics. The intra‐particle diffusion study revealed that external diffusion might be involved in this case. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41642.
Direct and Short Construction of the ACDE Ring System of Daphenylline
Authors: Wang Wei , Li Guo‐Ping , Wang Shao‐Feng , Shi Zi‐Fa , Cao Xiao‐Ping 
Published: November 2014

AbstractDaphenylline, a novel daphniphyllum alkaloid, boasts a fused and bridging ring system coupled with six stereogenic centers. Here we present a direct and short construction of the ACDE ring system of daphenylline from the known 3‐(2‐bromophenyl)propanal in 10 steps and 17 % overall yield. The synthesis features an iron(III)‐catalyzed aza‐Cope‐Mannich reaction, a self‐terminating 6‐exo‐trig aryl radical‐alkene cyclization and an intramolecular Friedel–Crafts acylation.
Excess surface area in bioelectrochemical systems causes ion transport limitations
Authors: Harrington Timothy D. , Babauta Jerome T. , Davenport Emily K. , Renslow Ryan S. , Beyenal Haluk 
Published: November 2014

ABSTRACTWe investigated ion transport limitations on 3D graphite felt electrodes by growing Geobacter sulfurreducens biofilms with advection to eliminate external mass transfer limitations. We characterized ion transport limitations by: (i) showing that serially increasing NaCl concentration up to 200 mM increased current linearly up to a total of +273% vs. 0 mM NaCl under advective conditions; (ii) growing the biofilm with a starting concentration of 200 mM NaCl, which led to a maximum current increase of 400% vs. current generation without NaCl, and (iii) showing that un‐colonized surface area remained even after steady‐state current was reached. After accounting for iR effects, we confirmed that the excess surface area existed despite a non‐zero overpotential. The fact that the biofilm was constrained from colonizing and producing further current under these conditions confirmed the biofilms under study here were ion transport‐limited. Our work demonstrates that the use of high surface area electrodes may not increase current density when the system design allows ion transport limitations to become dominant. Biotechnol. Bioeng. 2015;112: 858–866. © 2014 Wiley Periodicals, Inc.
Freeform inkjet printing of cellular structures with bifurcations
Authors: Christensen Kyle , Xu Changxue , Chai Wenxuan , Zhang Zhengyi , Fu Jianzhong , Huang Yong 
Published: November 2014

ABSTRACTOrgan printing offers a great potential for the freeform layer‐by‐layer fabrication of three‐dimensional (3D) living organs using cellular spheroids or bioinks as building blocks. Vascularization is often identified as a main technological barrier for building 3D organs. As such, the fabrication of 3D biological vascular trees is of great importance for the overall feasibility of the envisioned organ printing approach. In this study, vascular‐like cellular structures are fabricated using a liquid support‐based inkjet printing approach, which utilizes a calcium chloride solution as both a cross‐linking agent and support material. This solution enables the freeform printing of spanning and overhang features by providing a buoyant force. A heuristic approach is implemented to compensate for the axially‐varying deformation of horizontal tubular structures to achieve a uniform diameter along their axial directions. Vascular‐like structures with both horizontal and vertical bifurcations have been successfully printed from sodium alginate only as well as mouse fibroblast‐based alginate bioinks. The post‐printing fibroblast cell viability of printed cellular tubes was found to be above 90% even after a 24 h incubation, considering the control effect. Biotechnol. Bioeng. 2015;112: 1047–1055. © 2014 Wiley Periodicals, Inc.
Experimental evidence for growth advantage and metabolic shift stimulated by photophosphorylation of proteorhodopsin expressed in Escherichia coli at anaerobic condition
Authors: Wang Ying , Li Yan , Xu Tuan , Shi Zhenyu , Wu Qiong 
Published: November 2014

ABSTRACTSince solar light energy is the source of all renewable biological energy, the direct usage of light energy by bacterial cell factory has been a very attractive concept, especially using light energy to promote anaerobic fermentation growth and even recycle low‐energy carbon source when energy is the limiting factor. Proteorhodopsin(PR), a light‐driven proton pump proven to couple with ATP synthesis when expressed heterogeneously, is an interesting and simple option to enable light usage in engineered strains. However, although it was reported to influence fermentation in some cases, heterogeneous proteorhodopsin expression was never shown to support growth advantage or cause metabolic shift by photophosphorylation so far. Hereby, we presented the first experimental evidence that heterogeneously expressed proteorhodopsin can provide growth advantage and cause ATP‐dependent metabolism shift of acetate and lactate changes in Escherichia coli at anaerobic condition. Those discoveries suggest further application potential of PR in anaerobic fermentation where energy is a limiting factor. Biotechnol. Bioeng. 2015;112: 947–956. © 2014 Wiley Periodicals, Inc.
Chemical Synthesis of A Pore‐Forming Antimicrobial Protein, Caenopore‐5, by Using Native Chemical Ligation at a Glu‐Cys Site
Authors: Medini Karima , Harris Paul W. R. , Hards Kiel , Dingley Andrew J. , Cook Gregory M. , Brimble Margaret A. 
Published: November 2014

AbstractThe 2014 report from the World Health Organization (WHO) on antimicrobial resistance revealed an alarming rise in antibiotic resistance all around the world. Unlike classical antibiotics, with the exception of a few species, no acquired resistance towards antimicrobial peptides (AMPs) has been reported. Therefore, AMPs represent leads for the development of novel antibiotics. Caenopore‐5 is constitutively expressed in the intestine of the nematode Caenorhabditis elegans and is a pore‐forming AMP. The protein (82 amino acids) was successfully synthesised by using Boc solid‐phase peptide synthesis and native chemical ligation. No γ‐linked by‐product was observed despite the use of a C‐terminal Glu‐thioester. The folding of the synthetic protein was confirmed by 1H NMR spectroscopy and circular dichroism and compared with data recorded for recombinant caenopore‐5. The permeabilisation activities of the protein and of shortened analogues were evaluated.
Challenges in the Management of Giant Intraductal Breast Papilloma
Authors: Fatemi Yasaman , Hurley Rachel , Grant Clive , Henrichsen Tara , Chen Beiyun , Ghosh Karthik 
Published: November 2014

Key Clinical MessageThe differential diagnosis of a large breast mass in a post‐menopausal woman can include both benign and malignant etiologies. Although rare, diagnosis of giant intraductal papilloma must be considered in the differential. Furthermore, although benign, papillomas presenting as a large breast mass affecting the skin require extensive breast surgical treatment.
Magnetically Recoverable Palladium(0) Nanocomposite Catalyst for Hydrogenation Reactions in Water
Authors: Pélisson Carl‐Hugo , Denicourt‐Nowicki Audrey , Meriadec Cristelle , Greneche Jean‐Marc , Roucoux Alain 
Published: November 2014

AbstractAn easy and straightforward strategy has been used for loading palladium(0) nanoparticles onto the magnetic surface of maghemite (γ‐Fe2O3), without the use of organic modifiers. The nanocomposite was fully characterized by TEM, XRD, 57Fe Mössbauer spectroscopy, X‐ray photoelectron spectroscopy, and superconducting quantum interference device measurements. The Pd0@γ‐Fe2O3 nanocatalyst has been investigated in various catalytic reactions, under mild conditions (100 kPa H2, RT), and in neat water. Relevant catalytic activities were achieved in the hydrogenation of olefinic substrates, as well as in hydrodehalogenation reactions of halogenoarenes, that constitutes a promising process for wastewater treatment. These nanocatalysts proved also pertinent for the reduction of nitroarene derivatives into the corresponding anilines, which are promising substrates for fine chemistry. Finally, these catalysts proved to be easily recoverable through the use of an external magnet, without significant loss of activity.
Enzymatic Synthesis of a Key Intermediate for Rosuvastatin by Nitrilase‐Catalyzed Hydrolysis of Ethyl (R)‐4‐Cyano‐3‐hydroxybutyate at High Substrate Concentration
Authors: Yao Peiyuan , Li Jianjiong , Yuan Jing , Han Chao , Liu Xiangtao , Feng Jinhui , Wu Qiaqing , Zhu Dunming 
Published: November 2014

AbstractAn enzymatic method for the synthesis of ethyl (R)‐3‐hydroxyglutarate from ethyl (R)‐4‐cyano‐3‐hydroxybutyate was developed by using free and immobilized recombinant Escherichia coli BL21(DE3)pLysS harboring a nitrilase gene from Arabidopsis thaliana (AtNIT2). The hydrolysis of ethyl (R)‐4‐cyano‐3‐hydroxybutyate proceeded with the freely suspended cells of the biocatalyst under the optimized conditions of 1.5 mol L−1 (235.5 g L−1) substrate concentration and 6.0 wt % loading of wet cells at pH 8.0 and 25 °C, with 100 % conversion obtained in 4.5 h. Furthermore, immobilization of the whole cells enhanced their substrate tolerance, stability, and reusability. Under the optimized conditions (100 mmol L−1 tris(hydroxymethyl)aminomethane hydrochloride buffer, pH 8.0, 25 °C), the immobilized biocatalyst could be reused for up to 16 batches, with a biocatalyst productivity of 55.6 g gwet cells−1 and a space‐time productivity of 625.5 g L−1 d−1. These results demonstrated that the immobilized whole cells might be used as a biocatalyst in the industrial production of ethyl (R)‐3‐hydroxyglutarate, a key intermediate for the synthesis of rosuvastatin.