bluuebunny/crossref_metadata_2025_split huggingface dataset:
Glioblastoma Multiforme with Hypodipsic Hypernatremia in a Seven-Month-Old Golden Retriever
Authors: Engel Stephanie , Hilling Karen Marie , Meuten Travis Kuder , Frank Chad Brendan , Marolf Angela J. 
Published: August 2016

ABSTRACTPrimary hypodipsic hypernatremia is a rarely reported disease in dogs. Reported underlying causes associated with this disease in dogs include congenital malformations, encephalitis, intracranial neoplasia, and pressure atrophy of the hypothalamus secondary to hydrocephalus. The dog in this report had an infiltrative neoplastic disorder, likely causing damage to the hypothalamic osmoreceptors responsible for the thirst generation. The neoplastic process was identified histopathologically as glioblastoma multiforme, an unusual tumor to occur in a dog this young. A tumor of the central nervous system causing physical destruction of the osmoreceptors has rarely been reported in dogs and none of the previously reported cases involved a glial cell tumor.
A multifunctional GH39 glycoside hydrolase from the anaerobic gut fungusOrpinomycessp. strain C1A
Authors: Morrison Jessica M. , Elshahed Mostafa S. , Youssef Noha 
Published: August 2016

Background.The anaerobic gut fungi (phylum Neocallimastigomycota) represent a promising source of novel lignocellulolytic enzymes. Here, we report on the cloning, expression, and characterization of a glycoside hydrolase family 39 (GH39) enzyme (Bgxg1) that is highly transcribed by the anaerobic fungusOrpinomycessp. strain C1A under different growth conditions. This represents the first study of a GH39-family enzyme from the anaerobic fungi.Methods.Using enzyme activity assays, we performed a biochemical characterization of Bgxg1 on a variety of substrates over a wide range of pH and temperature values to identify the optimal enzyme conditions and the specificity of the enzyme. In addition, substrate competition studies and comparative modeling efforts were completed.Results.Contrary to the narrow range of activities (β-xylosidase or α-L-iduronidase) observed in previously characterized GH39 enzymes, Bgxg1 is unique in that it is multifunctional, exhibiting strong β-xylosidase, β-glucosidase, β-galactosidase activities (11.5 ± 1.2, 73.4 ± 7.15, and 54.6 ± 2.26 U/mg, respectively) and a weak xylanase activity (10.8 ± 1.25 U/mg), as compared to previously characterized enzymes. Further, Bgxg1 possesses extremely high affinity (as evident by the lowestKmvalues), compared to all previously characterized β-glucosidases, β-galactosidases, and xylanases. Physiological characterization revealed that Bgxg1 is active over a wide range of pH (3–8, optimum 6) and temperatures (25–60 °C, optimum 39 °C), and possesses excellent temperature and thermal stability. Substrate competition assays suggest that all observed activities occur at a single active site. Using comparative modeling and bioinformatics approaches, we putatively identified ten amino acid differences between Bgxg1 and previously biochemically characterized GH39 β-xylosidases that we speculate could impact active site architecture, size, charge, and/or polarity.Discussion.Collectively, the unique capabilities and multi-functionality of Bgxg1 render it an excellent candidate for inclusion in enzyme cocktails mediating cellulose and hemicellulose saccharification from lignocellulosic biomass.
Iron‐Catalyzed Azidoalkylthiation of Alkenes with Trimethylsilyl Azide and 1‐(Alkylthio)pyrrolidine‐2,5‐diones
Authors: Yu Jipan , Jiang Min , Song Zhixuan , He Tiancheng , Yang Haijun , Fu Hua 
Published: August 2016

AbstractA simple, efficient and practical iron‐catalyzed azidoarylthiation of alkenes has been developed at room temperature, and the corresponding products containing ortho‐sited sulfide and azide units were obtained in moderate to good yields with good tolerance of functional groups. The protocol uses readily available 1‐(alkylthio)pyrrolidine‐2,5‐diones and trimethylsilyl azide as the alkylthiation and azidation reagents, respectively, inexpensive and environmentally friendly iron chloride as the catalyst without addition of any ligand and additive.magnified image
Synthesis of Tricyclic Isoquinoline Derivatives via Palladium‐ Catalyzed Tandem Reactions of 2,7‐Alkadiynylic Carbonates with 2,3‐Allenyl Sulfamides
Authors: Huang Xin , Wu Wangteng , Song Shihua , Fu Chunling , Ma Shengming 
Published: August 2016

AbstractThe palladium‐catalyzed tandem reactions of 2,7‐alkadiynylic carbonates with 2,3‐allenyl sulfamides for the syntheses of fused tricycles such as 1,3,6,7,8,9‐hexahydrofuro[3,4‐h]isoquinoline, 2,3,6,7,8,9‐hexahydro‐1H‐pyrrolo[3,4‐h]isoquinoline, and 2,3,4,7,8,9‐hexahydro‐1H‐cyclopenta[h]isoquinoline derivatives have been developed. A mechanism has been proposed based on the isolation of a by‐product.magnified image
Iodine‐Mediated Aryl C−H Amination for the Synthesis of Benzimidazoles and Pyrido[1,2‐a]benzimidazoles
Authors: Lv Zhigang , Liu Jing , Wei Wei , Wu Jie , Yu Wenquan , Chang Junbiao 
Published: August 2016

AbstractAn intramolecular aryl C−H amination reaction has been achieved using molecular iodine as the sole oxidant for the synthesis of benzimidazole derivatives. The required substrates were readily prepared by addition or coupling of arylamines with the corresponding nitriles or aryl iodides. Iodine‐mediated oxidative cyclization of these substrates in the presence of potassium carbonate (K2CO3) as base afforded the corresponding products in moderate to good yields. The transition metal‐free protocol presented here is insensitive to air and operationally simple. This versatile and eco‐friendly synthetic methodology is broadly applicable to a variety of N‐aryl‐substituted amidines and pyridin‐2‐amines, and provides direct access to both 1H‐benzo[d]imidazole and pyrido[1,2‐a]benzimidazole derivatives from the corresponding precursors.magnified image
Phosphorylation of Glycine Derivatives via Copper(I)‐Catalyzed Csp3−H Bond Functionalization
Authors: Zhi Huizhen , Ung Sosthene Pierre‐Marie , Liu Yun , Zhao Liang , Li Chao‐Jun 
Published: August 2016

AbstractA simple and efficient one‐pot approach has been developed for a copper‐catalyzed phosphorylation of glycine derivatives under air and at room temperature. The present cross‐dehydrogenative coupling allows various methoxyphenyl‐protected glycine derivatives to be phosphorylated using diverse alkyl and aryl phosphites through an oxidative coupling between Csp3−H and P−H bonds catalyzed by copper iodide. This method provides a new synthetic tool to obtain biologically active α‐aminophosphonates.magnified image
Alkyne Metathesis with Silica‐Supported and Molecular Catalysts at Parts‐per‐Million Loadings
Authors: Estes Deven P. , Bittner Celine , Àrias Òscar , Casey Martin , Fedorov Alexey , Tamm Matthias , Copéret Christophe 
Published: August 2016

AbstractImprovement of the activity, stability, and chemoselectivity of alkyne‐metathesis catalysts is necessary before this promising methodology can become a routine method to construct C≡C triple bonds. Herein, we show that grafting of the known molecular catalyst [MesC≡Mo(OtBuF6)3] (1, Mes=2,4,6‐trimethylphenyl, OtBuF6=hexafluoro‐tert‐butoxy) onto partially dehydroxylated silica gave a well‐defined silica‐supported active alkyne‐metathesis catalyst [(≡SiO)Mo(≡CMes)(OtBuF6)2] (1/SiO2‐700). Both 1 and 1/SiO2‐700 showed very high activity, selectivity, and stability in the self‐metathesis of a variety of carefully purified alkynes, even at parts‐per‐million catalyst loadings. Remarkably, the lower turnover frequencies observed for 1/SiO2‐700 by comparison to 1 do not prevent the achievement of high turnover numbers. We attribute the lower reactivity of 1/SiO2‐700 to the rigidity of the surface Mo species owing to the strong interaction of the metal site with the silica surface.
Regiodivergent Intermolecular [3+2] Cycloadditions of Vinyl Aziridines and Allenes: Stereospecific Synthesis of Chiral Pyrrolidines
Authors: Lin Tao‐Yan , Zhu Chao‐Ze , Zhang Peichao , Wang Yidong , Wu Hai‐Hong , Feng Jian‐Jun , Zhang Junliang 
Published: August 2016

AbstractThe first rhodium‐catalyzed intermolecular [3+2] cycloaddition reaction of vinyl aziridines and allenes for the synthesis of enantioenriched functionalized pyrrolidines was realized. [3+2] cycloaddition with the proximal C=C bond of N‐allenamides gave 3‐methylene‐pyrrolidines in high regio‐ and diastereoselectivity, whereas, 2‐methylene‐pyrrolidines were obtained as the major products by the cycloadditions of vinyl aziridines with the distal C=C bond of allenes. Use of readily available starting materials, a broad substrate scope, high selectivity, mild reaction conditions, as well as versatile functionalization of the cycloadducts make this approach very practical and attractive.
Verzweigte Arylalkene aus Zimtsäuren: Selektivitätsumkehr in Heck‐Reaktionen durch Carboxylate als abfallende dirigierende Gruppen
Authors: Tang Jie , Hackenberger Dagmar , Goossen Lukas J. 
Published: August 2016

AbstractIn einer decarboxylierenden Mizoroki‐Heck‐Reaktion von Arylhalogeniden mit Zimtsäuren dirigiert die Carboxylatgruppe die Arylierung in β‐Position, bevor sie rückstandslos über eine Protodecarboxylierung entfernt wird. Unter Verwendung eines Kupfer/Palladium‐Katalysators können elektronenreiche wie ‐arme Arylbromide und ‐chloride mit verschiedenen funktionellen Gruppen mit breit verfügbaren Zimtsäuren selektiv zu 1,1‐disubstituierten Alkenen umgesetzt werden. Dieses Reaktionskonzept ergänzt hervorragend die traditionellen, 1,2‐selektiven Heck‐Reaktionen von Styrolen.
Morphological investigation of cellulose acetate/cellulose nanocrystal composites obtained by melt extrusion
Authors: Leite Liliane Samara Ferreira , Battirola Liliane Cristina , da Silva Laura Caetano Escobar , Gonçalves Maria do Carmo 
Published: August 2016

ABSTRACTComposites were prepared from cellulose acetate (CA) and cellulose nanocrystals (CNC) by melt extrusion using two methods for the introduction of CNC: direct mixing and predispersion in CA solution. CNC were isolated using hydrochloric acid to increase thermal stability allowing the composites to be processed above 150 °C. The effect of CNC dispersion on the composites morphology, thermal, and mechanical properties was investigated. Field emission scanning electron microscopy and transmission electron microscopy results indicated that the predispersion method allows better CNC dispersion and distribution when compared to the direct mixture method. In addition, predispersion promotes preferential CNC orientation in relation to the injection flow. The predispersion method also showed a 14% Young's modulus increase in composites containing 15 wt % CNC while no significant change was observed when using the direct mixing. The results obtained in this work show that, to achieve the percolation threshold, nanoparticle distribution is as important as their content. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 44201.
Lanthanide Organic Framework Luminescent Thermometers
Authors: Rocha João , Brites Carlos D. S. , Carlos Luís D. 
Published: August 2016

AbstractMetal–organic frameworks (MOFs) are excellent platforms for engineering luminescence properties as their building blocks, metal ions, linkers, and guest ions or molecules, are all potential sources of light emission. Temperature is one of the most important physical properties affecting the dynamics and viability of natural and engineered systems. Because the luminescence of certain lanthanide‐bearing MOFs changes considerably with temperature, in the last few years, these materials have been explored as optical thermometers, especially in temperature sensing based on the intensity ratios of two separate electronic transitions. This review discusses the main concepts and ideas assisting the design of such ratiometric thermometers, and identifies the main challenges presented to this nascent field: develop nanothermometers for bio‐applications and nanomedicine; understand the energy transfer mechanisms determining the thermal sensitivity; achieve effective primary thermometers; realize multifunctional nanothermometers; integrate Ln3+‐based thermometers in commercial products.
A Molecular Rotor that Measures Dynamic Changes of Lipid Bilayer Viscosity Caused by Oxidative Stress
Authors: Vyšniauskas Aurimas , Qurashi Maryam , Kuimova Marina K. 
Published: August 2016

AbstractOxidation of cellular structures is typically an undesirable process that can be a hallmark of certain diseases. On the other hand, photooxidation is a necessary step of photodynamic therapy (PDT), a cancer treatment causing cell death upon light irradiation. Here, the effect of photooxidation on the microscopic viscosity of model lipid bilayers constructed of 1,2‐dioleoyl‐sn‐glycero‐3‐phosphocholine has been studied. A molecular rotor has been employed that displays a viscosity‐dependent fluorescence lifetime as a quantitative probe of the bilayer's viscosity. Thus, spatially‐resolved viscosity maps of lipid photooxidation in giant unilamellar vesicles (GUVs) were obtained, testing the effect of the positioning of the oxidant relative to the rotor in the bilayer. It was found that PDT has a strong impact on viscoelastic properties of lipid bilayers, which ‘travels’ through the bilayer to areas that have not been irradiated directly. A dramatic difference in viscoelastic properties of oxidized GUVs by Type I (electron transfer) and Type II (singlet oxygen‐based) photosensitisers was also detected.
3‐Bromo‐2‐Pyrone: An Alternative and Convenient Route to Functionalized Phosphinines
Authors: Habicht Marija H. , Wossidlo Friedrich , Weber Manuela , Müller Christian 
Published: August 2016

AbstractThe facile access to 3‐bromo‐2‐pyrone allows the preparation of 6‐bromo‐2‐trimethylsilyl‐phosphinine by a [4+2] cycloaddition with Me3Si‐C≡P for the first time. The regioselectivity of this reaction could be verified by means of single crystal X‐ray diffraction of the corresponding W0 complex. In the presence of ZnBr2 and dppp (1,3‐bis(diphenylphosphino)propane) as a bidentate ligand, the bromo‐phosphinine quantitatively undergoes a Negishi cross‐coupling reaction with PhLi that selectively leads to 6‐phenyl‐2‐trimethylsilyl‐phosphinine. This heterocycle could again be characterized by means of X‐ray diffraction as a W0 complex. These results describe a new and convenient route to 2,6‐disubstituted phosphinines that makes use of readily available starting materials.
Enhanced Photocatalytic Performance of ZnO Nanorods Coupled by Two‐Dimensional α‐MoO3 Nanoflakes under UV and Visible Light Irradiation
Authors: Hang Da‐Ren , Sharma Krishna Hari , Chen Chun‐Hu , Islam Sk Emdadul 
Published: August 2016

AbstractWe exploit the utilization of two‐dimensional (2D) molybdenum oxide nanoflakes as a co‐catalyst for ZnO nanorods (NRs) to enhance their photocatalytic performance. The 2D nanoflakes of orthorhombic α‐MoO3 were synthesized through a sonication‐aided exfoliation technique. The 2D MoO3 nanoflakes can be further converted to substoichiometric quasi‐metallic MoO3−x by using UV irradiation. Subsequently, 1D–2D MoO3/ZnO NR and MoO3−x/ZnO NR composite photocatalysts have been successfully synthesized. The photocatalytic performances of the novel nanosystems in the decomposition of methylene blue are studied by using UV‐ and visible‐illumination setup. The incorporated 2D nanoflakes show a positive influence on the photocatalytic activity of the ZnO. The obtained rate constant values follow the order of pristine ZnO NR<MoO3/ZnO NR<MoO3−x/ZnO NR composites. The enhancement of the photocatalytic efficiency can be ascribed to a fast charge carrier separation and transport within the heterojunctions of the MoO3/ZnO NRs. In particular, the best photocatalytic performance of the MoO3−x/ZnO NR composite can be additionally attributed to a quasi‐metallic conductivity and substoichiometry‐induced mid‐gap states, which extend the light absorption range. A tentative photocatalytic degradation mechanism was proposed. The strategy presented in this work not only demonstrates that coupling with nanoscale molybdenum oxide nanoflakes is a promising approach to significantly enhance the photocatalytic activity of ZnO but also hints at new type of composite catalyst with extended applications in energy conversion and environmental purification.
Spectroscopically Characterized Synthetic Mononuclear Nickel–Oxygen Species
Authors: Corona Teresa , Company Anna 
Published: August 2016

AbstractIron, copper, and manganese are the predominant metals found in oxygenases that perform efficient and selective hydrocarbon oxidations and for this reason, a large number of the corresponding metal–oxygen species has been described. However, in recent years nickel has been found in the active site of enzymes involved in oxidation processes, in which nickel–dioxygen species are proposed to play a key role. Owing to this biological relevance and to the existence of different catalytic protocols that involve the use of nickel catalysts in oxidation reactions, there is a growing interest in the detection and characterization of nickel–oxygen species relevant to these processes. In this Minireview the spectroscopically/structurally characterized synthetic superoxo, peroxo, and oxonickel species that have been reported to date are described. From these studies it becomes clear that nickel is a very promising metal in the field of oxidation chemistry with still unexplored possibilities.
Asymmetric Assembly of All‐Carbon Tertiary/Quaternary Nonadjacent Stereocenters through Organocatalytic Conjugate Addition of α‐Cyanoacetates to a Methacrylate Equivalent
Authors: Iriarte Igor , Vera Silvia , Badiola Eider , Mielgo Antonia , Oiarbide Mikel , García Jesús M. , Odriozola José M. , Palomo Claudio 
Published: August 2016

AbstractAn efficient, highly diastereo‐ and enantioselective assembly of acyclic carbonyl fragments possessing nonadjacent all‐carbon tertiary/quaternary stereoarrays is reported based on a Brønsted base catalyzed Michael addition/α‐protonation sequence involving α‐cyanoacetates and 2,4‐dimethyl‐4‐hydroxypenten‐3‐one as novel methacrylate equivalent.
Vogelspinne zeigt neue Schmerz‐Wege
Authors: Groß Michael 
Published: August 2016

AbstractIm Gift einer handtellergroßen westafrikanischen Vogelspinne fanden Forscher zwei Peptide, die in Nervenzellen gezielt einen Ionenkanal blockieren, dessen Funktion bisher unbekannt war, aber nun mit diesen Molekülen untersucht werden kann.
Metal–Organic Coordination versus Hydrogen Bonding: Highly Efficient Templated Photocycloadditions of Trisubstituted Isomeric Olefins in the Solid State
Authors: Elacqua Elizabeth , Sinnwell Michael A. , Loren Bradley P. , Jurgens Paul T. , Groeneman Ryan H. , Reinheimer Eric W. , MacGillivray Leonard R. 
Published: August 2016

AbstractTrisubstituted olefins are reactants in template‐directed, solid‐state [2+2] photocycloaddition reactions. Whereas hydrogen‐bond‐based templates afford crystalline assemblies with olefins that are photostable, AgI coordination results in carbon–carbon double bonds that react stereoselectively and result in quantitative yield.
Covalent Attachment of the Water‐insoluble Ni(PCy2NPhe2)2 Electrocatalyst to Electrodes Showing Reversible Catalysis in Aqueous Solution
Authors: Rodríguez‐Maciá Patricia , Priyadarshani Nilusha , Dutta Arnab , Weidenthaler Claudia , Lubitz Wolfgang , Shaw Wendy J. , Rüdiger Olaf 
Published: August 2016

AbstractHydrogenases are a diverse group of metalloenzymes which catalyze the reversible conversion between molecular hydrogen and protons at high rates. The catalytic activity of these enzymes does not require overpotential because their active site has been evolutionarily optimized to operate fast and efficiently. These enzymes have inspired the development of molecular catalysts, which have dramatically improved in efficiency in recent years, to the point that some synthetic catalysts even outperform hydrogenases under certain conditions. In this work, we use a reversible noble‐metal‐free homogeneous catalyst, the [Ni(PCy2NPhe2)2]2+ complex, and we covalently immobilize it on a functionalized highly oriented pyrolytic graphite “edge” (HOPGe) electrode surface. This catalyst is not water soluble, but once it is surface‐confined on the electrode, it maintains its catalytic properties in aqueous solutions, showing reversibility for H2 oxidation/reduction. Immobilization of the [Ni(PCy2NPhe2)2]2+ complex onto a multi‐walled carbon nanotubes coated electrode leads to even higher catalytic current densities and enhanced stability.
Cost‐effective non‐metric photogrammetry from consumer‐grade sUAS: implications for direct georeferencing of structure from motion photogrammetry
Authors: Carbonneau Patrice E. , Dietrich James T. 
Published: August 2016

AbstractThe declining costs of small Unmanned Aerial Systems (sUAS), in combination with Structure‐from‐Motion (SfM) photogrammetry have triggered renewed interest in image‐based topography reconstruction. However, the potential uptake of sUAS‐based topography is limited by the need for ground control acquired with expensive survey equipment. Direct georeferencing (DG) is a workflow that obviates ground control and uses only the camera positions to georeference the SfM results. However, the absence of ground control poses significant challenges in terms of the data quality of the final geospatial outputs. Notably, it is generally accepted that ground control is required to georeference, refine the camera calibration parameters, and remove any artefacts of optical distortion from the topographic model. Here, we present an examination of DG carried out with low‐cost consumer‐grade sUAS. We begin with a study of surface deformations resulting from systematic perturbations of the radial lens distortion parameters. We then test a number of flight patterns and develop a novel error quantification method to assess the outcomes. Our perturbation analysis shows that there exists families of predictable equifinal solutions of K1‐K2 which minimize doming in the output model. The equifinal solutions can be expressed as K2 = f (K1) and they have been observed for both the DJI Inspire 1 and Phantom 3 sUAS platforms. This equifinality relationship can be used as an external reliability check of the self‐calibration and allow a DG workflow to produce topography exempt of non‐affine deformations and with random errors of 0.1% of the flying height, linear offsets below 10 m and off‐vertical tilts below 1°. Whilst not yet of survey‐grade quality, these results demonstrate that low‐cost sUAS are capable of producing reliable topography products without recourse to expensive survey equipment and we argue that direct georeferencing and low‐cost sUAS could transform survey practices in both academic and commercial disciplines. Copyright © 2016 John Wiley & Sons, Ltd.
Tricoordinate Organochromium(III) Complexes Supported by a Bulky Silylamido Ligand Produce Ultra‐High‐Molecular Weight Polyethylene in the Absence of Activators
Authors: Liu Hsueh‐Ju , Cai Irene C. , Fedorov Alexey , Ziegler Micah S. , Copéret Christophe , Tilley T. Don 
Published: August 2016

Low‐coordinate organoCr(III) complexes supported by the silylamido ligand –N(SiMe3)DIPP (DIPP = 2,6‐diisopropylphenyl) are ethylene polymerization catalyst precursors without the need of additional cocatalyst. The reaction of CrCl3(THF)3 with 3 or 2 equiv. of LiN(SiMe3)DIPP yields either a four‐membered cyclometalated Cr complex or Cr[N(SiMe3)DIPP]2Cl, respectively, with no trace of Cr[N(SiMe3)DIPP]3. Addition of 1 equiv. of LiN(SiMe3)DIPP to Cr[N(SiMe3)DIPP]2Cl also leads to the four‐membered metallacycle, which upon heating transforms to a new six‐membered Cr metallacycle, likely via a σ‐bond metathesis step. Cr[N(SiMe3)DIPP]2Cl can be readily converted to bis(amido)Cr(III) vinyl and alkyl complexes Cr[N(SiMe3)DIPP]2R (R = vinyl, Bn, and Me). All of these structurally characterized low‐coordinate Cr(III) complexes with a Cr–C bond initiate the polymerization of ethylene in the absence of activators or cocatalysts, producing ultra‐high‐molecular weight polyethylene.