bluuebunny/crossref_metadata_2025_split huggingface dataset:
Long-lived Dust Asymmetries at Dead Zone Edges in Protoplanetary Disks
Authors: Miranda Ryan , Li Hui , Li Shengtai , Jin Sheng 
Published: January 2017

Abstract
A number of transition disks exhibit significant azimuthal asymmetries in thermal dust emission. One possible origin for these asymmetries is dust trapping in vortices formed at the edges of dead zones. We carry out high-resolution, two-dimensional hydrodynamic simulations of this scenario, including the effects of dust feedback. We find that, although feedback weakens the vortices and slows down the process of dust accumulation, the dust distribution in the disk can nonetheless remain asymmetric for many thousands of orbits. We show that even after 104 orbits, or 2.5 Myr when scaled to the parameters of Oph IRS 48 (a significant fraction of its age), the dust is not dispersed into an axisymmetric ring, in contrast to the case of a vortex formed by a planet. This is because accumulation of mass at the dead zone edge constantly replenishes the vortex, preventing it from being fully destroyed. We produce synthetic dust emission images using our simulation results. We find that multiple small clumps of dust may be distributed azimuthally. These clumps, if not resolved from one another, appear as a single large feature. A defining characteristic of a disk with a dead zone edge is that an asymmetric feature is accompanied by a ring of dust located about twice as far from the central star.
H i-to-H2 Transition Layers in the Star-forming Region W43
Authors: Bialy Shmuel , Bihr Simon , Beuther Henrik , Henning Thomas , Sternberg Amiel 
Published: January 2017

Abstract
The process of atomic-to-molecular (H i-to-H2) gas conversion is fundamental for molecular-cloud formation and star formation. 21 cm observations of the star-forming region W43 revealed extremely high H i column densities, of 120–180

, a factor of 10–20 larger than predicted by H i-to-H2 transition theories. We analyze the observed H i with a theoretical model of the H i-to-H2 transition, and show that the discrepancy between theory and observation cannot be explained by the intense radiation in W43, nor be explained by variations of the assumed volume density or H2 formation rate coefficient. We show that the large observed H i columns are naturally explained by several (9–22) H i-to-H2 transition layers, superimposed along the sightlines of W43. We discuss other possible interpretations such as a non-steady-state scenario and inefficient dust absorption. The case of W43 suggests that H i thresholds reported in extragalactic observations are probably not associated with a single H i-to-H2 transition, but are rather a result of several transition layers (clouds) along the sightlines, beam-diluted with diffuse intercloud gas.
Probing the Broad-Line Region and the Accretion Disk in the Lensed Quasars HE 0435-1223, WFI 2033-4723, and HE 2149-2745 Using Gravitational Microlensing
Authors: Motta V. , Mediavilla E. , Rojas K. , Falco E. E. , Jiménez-Vicente J. , Muñoz J. A. 
Published: January 2017

Abstract
We use single-epoch spectroscopy of three gravitationally lensed quasars, HE 0435-1223, WFI 2033-4723, and HE 2149-2745, to study their inner structure (broad-line region [BLR] and continuum source). We detect microlensing-induced magnification in the wings of the broad emission lines of two of the systems (HE 0435-1223 and WFI 2033-4723). In the case of WFI 2033-4723, microlensing affects two “bumps” in the spectra that are almost symmetrically arranged on the blue (coincident with an Al iii emission line) and red wings of C iii]. These match the typical double-peaked profile that follows from disk kinematics. The presence of microlensing in the wings of the emission lines indicates the existence of two different regions in the BLR: a relatively small one with kinematics possibly related to an accretion disk, and another one that is substantially more extended and insensitive to microlensing. There is good agreement between the estimated size of the region affected by microlensing in the emission lines,

lt-day (red wing of C iv in HE 0435-1223) and

lt-day (C iii] bumps in WFI 2033-4723), and the sizes inferred from the continuum emission,

lt-day (HE 0435-1223) and

lt-day (WFI 2033-4723). For HE 2149-2745 we measure an accretion disk size

lt-day. The estimates of p, the exponent of the size versus wavelength (

), are 1.2 ± 0.6, 0.8 ± 0.2, and 0.4 ± 0.3 for HE 0435-1223, WFI 2033-4723, and HE 2149-2745, respectively. In conclusion, the continuum microlensing amplitude in the three quasars and chromaticity in WFI 2033-4723 and HE 2149-2745 are below expectations for the thin-disk model. The disks are larger and their temperature gradients are flatter than predicted by this model.
ΛCDM is Consistent with SPARC Radial Acceleration Relation
Authors: Keller B. W. , Wadsley J. W. 
Published: January 2017

Abstract
Recent analysis of the Spitzer Photometry and Accurate Rotation Curve (SPARC) galaxy sample found a surprisingly tight relation between the radial acceleration inferred from the rotation curves and the acceleration due to the baryonic components of the disk. It has been suggested that this relation may be evidence for new physics, beyond ΛCDM. In this Letter, we show that 32 galaxies from the MUGS2 match the SPARC acceleration relation. These cosmological simulations of star-forming, rotationally supported disks were simulated with a WMAP3 ΛCDM cosmology, and match the SPARC acceleration relation with less scatter than the observational data. These results show that this acceleration relation is a consequence of dissipative collapse of baryons, rather than being evidence for exotic dark-sector physics or new dynamical laws.
Identificação da concepção ambiental dos moradores do entorno da lagoa central do município de Lagoa Alegre – PI
Authors: Reis Adriana Saraiva , Andrade Amanda Rejalma Moraes , Castro Isabela Melo , Moita Neto José Machado 
Published: January 2017

O presente trabalho tem por objetivo identificar a visão dos moradores do Município de Lagoa Alegre - PI sobre as mudanças sofridas pela lagoa central. Para tanto, realizou-se uma pesquisa descritiva de caráter quali-quantitativo em que foram realizadas visitas in loco e registros fotográficos da área em estudo para identificar a ação antrópica sobre o ambiente, além da aplicação de formulários aos moradores do entorno (com questionamentos sobre condições de saneamento local, utilização da lagoa para atividades diversas e competências para revitalização do manancial). De acordo com a visão dos moradores, ocorreram mudanças significativas na lagoa. Dessa forma, os impactos gerados nesse manancial precisam ser monitorados e minimizados, principalmente pelas autoridades locais, através da criação de projetos de gestão e educação ambiental que venham a auxiliar a sua revitalização, ações essas que podem colaborar para transformações sociais e ambientais.
Factors limiting the gains of MDGs in the Democratic Republic of the Congo: KEY DETERMINANT AND PITFALLS FOR FRAGILE STATES
Authors: Ndaguba Emeka A. , Okarah Anthony , Ukanwah Chijioke Hope , Nebo Godwin , Ndaguba Solomon U. 
Published: January 2017

The Human Development Index in 2013 ranked Democratic Republic of the Congo 186th out of 187 in the United Nations Development Programme. The categorization came as a result of the deteriorating conflict that pushed the country towards a failed state realm. According to the 2015 Fragility Index of thePeaceFund, Democratic Republic of the Congo was among the nations ranked on the high alert (highly vulnerable andvolatile), consequently to as a result of non-provision of basic services. In addition to the deteriorating growth and development trajectory, infrastructural and systems failures have unabatedly limited service provision, resulting in inadequacies in humanitarian interventions. The study aims to evaluate the gains of MDGs in Democratic Republic of the Congo, taking into cognizance key deliverables, pitfalls, and prospects for development in fragile states. The study uses thematic reviews cushioned with elements of quantitative approach in providing answers to the study. On surface value, the study shows that 72% of rural households live in abject poverty. Additionally, more than 40% of children in rural areas suffer from chronic malnutrition, hunger and squalor. The study contends that without sustainable public institutions, systems and structure in the administration of services, DRC could likely remain in unending retrogression.
Efficient Synthesis of (R)‐2‐Chloro‐1‐(2,4‐dichlorophenyl)ethanol with a Ketoreductase from Scheffersomyces stipitis CBS 6045
Authors: Shang Yue‐Peng , Chen Qi , Kong Xu‐Dong , Zhang Yu‐Jun , Xu Jian‐He , Yu Hui‐Lei 
Published: January 2017

AbstractBy enzyme screening, a ketoreductase cloned from Scheffersomyces stipitis CBS 6045 and named SsCR was identified that could catalyze the asymmetric hydrogenation of a variety of aromatic ketones. SsCR exhibited a specific activity of 65 U mg−1 protein and excellent enantioselectivity (99.9% ee) towards the hydrophobic substrate 2‐chloro‐1‐(2,4‐dichlorophenyl)ethanone, which is an intermediate in the synthesis of common antifungal agents such as miconazole, econazole and sertaconazole. The kinetic parameter kcat/Km was 4.51×103 s−1 mM−1, showing the great catalytic efficiency of SsCR towards this substrate. Molecular dynamic simulation results shed light on the higher substrate binding free energy change for this substrate relative to other substrates. Based on the good catalytic properties of SsCR, (R)‐2‐chloro‐1‐(2,4‐dichlorophenyl)ethanol could be obtained with a space‐time yield (STY) of up to 268 g L−1 d−1 without any additional cofactor required in the reductive reaction process. On scaling up the bioreaction, the (R)‐alcohol was isolated with 88.2% yield and 99.9% ee. The environmental factor (E factor) of this reaction was 7.25 when process water was excluded.magnified image
Regioselective Enzymatic Carboxylation of Bioactive (Poly)phenols
Authors: Plasch Katharina , Resch Verena , Hitce Julien , Popłoński Jarosław , Faber Kurt , Glueck Silvia M. 
Published: January 2017

AbstractIn order to extend the applicability of the regioselective enzymatic carboxylation of phenols, the substrate scope of o‐benzoic acid (de)carboxylases has been investigated towards complex molecules with an emphasis on flavouring agents and polyphenols possessing antioxidant properties. o‐Hydroxycarboxylic acid products were obtained with perfect regioselectivity, in moderate to excellent yields. The applicability of this method was proven by the regioselective bio‐carboxylation of resveratrol on a preparative scale with 95% yield.magnified image
Falsch‐positiver Treffer im Fragment‐basierten Wirkstoffdesign: Lass Dich nicht auf die falsche Fährte locken!
Authors: Cramer Jonathan , Schiebel Johannes , Wulsdorf Tobias , Grohe Kristof , Najbauer Eszter Eva , Ehrmann Frederik R. , Radeva Nedyalka , Zitzer Nina , Linne Uwe , Linser Rasmus , Heine Andreas , Klebe Gerhard 
Published: January 2017

AbstractDie wachsende Beliebtheit Fragment‐basierter Strategien zur Entwicklung neuer Wirkstoffe macht es notwendig, falsch‐positive Treffer aus affinitätsbasierten Screening‐Kampagnen frühzeitig zu erkennen. Die geringe Größe und niedrige Affinität von Fragmenten bewirkt, dass viele der verwendeten Methoden an den Rand ihrer Nachweisgrenze gelangen. Die unbeabsichtigte Verfolgung einer falschen Fährte kann jedoch zu einem erheblichen Verlust an Zeit und Ressourcen führen. Diese Arbeit untersucht die Ursache für irreführende Ergebnisse aus affinitätsbasierten Screening‐Experimenten für ein Fragment, das von mehreren Methoden als hochpotenter Binder der Aspartylprotease Endothiapepsin (EP) identifiziert wurde. Die biologische Aktivität dieses Moleküls resultiert hauptsächlich aus der spontanen Bildung einer neuen Verbindung durch weitläufige Umlagerung eines heterocyclischen Grundgerüstes. Der neu gebildete Ligand bindet an EP durch induzierte Anpassung des Proteins, wobei die Ausbildung bemerkenswerter elektrostatischer Wechselwirkungen resultiert. Es zeigt sich, dass strukturelle Informationen für die Identifizierung dieses falsch‐positiven Treffers unabdingbar waren.
Odd–Even Alternation in Tautomeric Porous Organic Cages with Exceptional Chemical Stability
Authors: Bera Saibal , Basu Arghya , Tothadi Srinu , Garai Bikash , Banerjee Subhrashis , Vanka Kumar , Banerjee Rahul 
Published: January 2017

AbstractAmine‐linked (C−NH) porous organic cages (POCs) are preferred over the imine‐linked (C=N) POCs owing to their enhanced chemical stability. In general, amine‐linked cages, obtained by the reduction of corresponding imines, are not shape‐persistent in the crystalline form. Moreover, they require multistep synthesis. Herein, a one‐pot synthesis of four new amine‐linked organic cages by the reaction of 1,3,5‐triformylphloroglucinol (Tp) with different analogues of alkanediamine is reported. The POCs resulting from the odd diamine (having an odd number of −CH2 groups) is conformationally eclipsed, while the POCs constructed from even diamines adopt a gauche conformation. This odd–even alternation in the conformation of POCs has been supported by computational calculations. The synthetic strategy hinges on the concept of Schiff base condensation reaction followed by keto–enol tautomerization. This mechanism is the key for the exceptional chemical stability of cages and facilitates their resistance towards acids and bases.
Stereocontrolled Total Synthesis of (−)‐Stemaphylline
Authors: Varela Ana , Garve Lennart K. B. , Leonori Daniele , Aggarwal Varinder K. 
Published: January 2017

AbstractHomologation of readily available α‐boryl pyrrolidines with metal carbenoids is especially challenging even when good leaving groups (Cl−) are employed. By performing a solvent switch from Et2O to CHCl3, efficient 1,2‐metalate rearrangement of the intermediate boronate occurs with both halide and ester leaving groups. The methodology was used in the total synthesis of the Stemona alkaloid (−)‐stemaphylline in just 11 steps (longest linear sequence), with high stereocontrol (>20:1 d.r.) and 11 % overall yield. The synthesis also features a late‐stage lithiation–borylation reaction with a tertiary amine containing carbenoid.
Breaking the Tetra‐Coordinated Framework Rule: New Clathrate Ba8M24P28+δ (M=Cu/Zn)
Authors: Dolyniuk Juli‐Anna , Zaikina Julia V. , Kaseman Derrick C. , Sen Sabyasachi , Kovnir Kirill 
Published: January 2017

AbstractA new clathrate type has been discovered in the Ba/Cu/Zn/P system. The crystal structure of the Ba8M24P28+δ (M=Cu/Zn) clathrate is composed of the pentagonal dodecahedra common to clathrates along with a unique 22‐vertex polyhedron with two hexagonal faces capped by additional partially occupied phosphorus sites. This is the first example of a clathrate compound where the framework atoms are not in tetrahedral or trigonal‐pyramidal coordination. In Ba8M24P28+δ a majority of the framework atoms are five‐ and six‐coordinated, a feature more common to electron‐rich intermetallics. The crystal structure of this new clathrate was determined by a combination of X‐ray and neutron diffraction and was confirmed with solid‐state 31P NMR spectroscopy. Based on chemical bonding analysis, the driving force for the formation of this new clathrate is the excess of electrons generated by a high concentration of Zn atoms in the framework. The rattling of guest atoms in the large cages results in a very low thermal conductivity, a unique feature of the clathrate family of compounds.
Gold‐Catalyzed [3+2]/Retro‐[3+2]/[3+2] Cycloaddition Cascade Reaction of N‐Alkoxyazomethine Ylides
Authors: Sugita Shoichi , Takeda Norihiko , Tohnai Norimitsu , Miyata Mikiji , Miyata Okiko , Ueda Masafumi 
Published: January 2017

AbstractA novel cascade reaction has been developed for the synthesis of 2,6‐methanopyrrolo[1,2‐b]isoxazoles based on the gold‐catalyzed generation of an N‐allyloxyazomethine ylide. This reaction involves sequential [3+2]/retro‐[3+2]/[3+2] cycloaddition reactions, thus providing facile access to fused and bridged heterocycles which would be otherwise difficult to prepare using existing synthetic methods. Notably, this reaction allows the efficient construction of three C−C bonds, one C−O bond, one C−N bond and one C−H bond, as well as the cleavage of one C−C bond, one C−O bond and one C−H bond in a single operation. The intermolecular cycloaddition of an N‐allyloxyazomethine ylide and the subsequent application of the product to the synthesis of tropenol is also described.
Visible‐Light‐Mediated Remote Aliphatic C−H Functionalizations through a 1,5‐Hydrogen Transfer Cascade
Authors: Shu Wei , Nevado Cristina 
Published: January 2017

AbstractA redox‐neutral, light‐mediated functionalization of unactivated C(sp3)−H bonds via iminyl radicals is presented here. A 1,5‐H transfer followed by the functionalization of a C(sp2)−H bond takes place in aqueous media producing a variety of elaborated fused ketones. Mechanistic investigations have revealed 1,5‐H transfer as the reversible, rate‐determining step in this transformation. Divergent scaffolds are also accessible via C(sp3)−N bond formation upon a careful choice of the reaction additives.
Biosynthesis of the Carbonylmethylene Structure Found in the Ketomemicin Class of Pseudotripeptides
Authors: Kawata Junpei , Naoe Taiki , Ogasawara Yasushi , Dairi Tohru 
Published: January 2017

AbstractWe recently discovered novel pseudotripeptides, the ketomemicins, which possess a C‐terminal pseudodipeptide connected with a carbonylmethylene instead of an amide bond, through heterologous expression of gene clusters identified in actinobacteria. The carbonylmethylene structure is a stable isostere of the amide bond and its biological significance has been shown in several natural and synthetic products. Despite the biological importance of these compounds, little is known about how the carbonylmethylene structure is biosynthesized. In this work, we fully characterized the biosynthetic machinery of the pseudodipeptide. An aldolase, dehydratase, PLP‐dependent glycine‐C‐acetyltransferase, and dehydrogenase were involved in the formation of the pseudodipeptide, with malonyl‐CoA and phenylpyruvate as starter substrates.
Solution Synthesis, Structure, and CO2 Reduction Reactivity of a Scandium(II) Complex, {Sc[N(SiMe3)2]3}−
Authors: Woen David H. , Chen Guo P. , Ziller Joseph W. , Boyle Timothy J. , Furche Filipp , Evans William J. 
Published: January 2017

AbstractThe first crystallographically characterizable complex of Sc2+, [Sc(NR2)3]− (R=SiMe3), has been obtained by LnA3/M reactions (Ln=rare earth metal; A=anionic ligand; M=alkali metal) involving reduction of Sc(NR2)3 with K in the presence of 2.2.2‐cryptand (crypt) and 18‐crown‐6 (18‐c‐6) and with Cs in the presence of crypt. Dark maroon [K(crypt)]+, [K(18‐c‐6)]+, and [Cs(crypt)]+ salts of the [Sc(NR2)3]− anion are formed, respectively. The formation of this oxidation state of Sc is also indicated by the eight‐line EPR spectra arising from the I=7/2 45Sc nucleus. The Sc(NR2)3 reduction differs from Ln(NR2)3 reactions (Ln=Y and lanthanides) in that it occurs under N2 without formation of isolable reduced dinitrogen species. [K(18‐c‐6)][Sc(NR2)3] reacts with CO2 to produce an oxalate complex, {K2(18‐c‐6)3}{[(R2N)3Sc]2(μ‐C2O4‐κ1O:κ1O′′)}, and a CO2− radical anion complex, [(R2N)3Sc(μ‐OCO‐κ1O:κ1O′)K(18‐c‐6)]n.
Compatibilization of polyhedral oligomeric silsesquioxane for polypropylene–titanium dioxide composites and effect of the processing temperature
Authors: Li Xiao , Mao Hongda , Liu Yuansen , Nie Min , Wang Qi 
Published: January 2017

ABSTRACTPolyhedral oligomeric silsesquioxanes (POSSs), with inorganic cores, offer excellent mechanical properties and have external organic substituents. On the basis of their hybrid organic−inorganic characteristics, which allow for a tunable reaction or miscibility with various materials, in this study, we introduced a bifunctional POSS as a novel rigid compatibilizer for polypropylene (PP)–titanium dioxide (TiO2) composites and evaluated its compatibilizing effects at different processing temperatures. The results show that the attached hydroxyl and isobutyl groups allowed for the reaction with TiO2 and miscibility with the PP matrix. However, at lower processing temperatures, POSS existed in the form of solid particles, and its interfacial absorption was too poor for sufficient coverage of the TiO2 surface; this resulted in a weak compatibilization effect on the PP–TiO2 composite. When the processing temperature was increased to 240 °C, the solid POSS turned into a liquid and thus had strong mobility; this was favorable for the diffusion of TiO2 onto the surface and the construction of a strong interfacial phase. Because the rigid characteristic of POSS made a positive contribution to the performances of the composites, the PP–TiO2 composites prepared at higher processing temperatures exhibited better mechanical properties, with the maximum increases occurring in the compositions containing 5 wt % POSS. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44766
Chemically modified cellulose nanofibril as an additive for two‐component polyurethane coatings
Authors: Virtanen Sanna , Jämsä Saila , Talja Riku , Heikkinen Harri , Vuoti Sauli 
Published: January 2017

ABSTRACTThe increasing demand for the use of sustainable materials in industrial applications has created an urge to develop technologies that enable the use of biopolymers such as cellulose for the improvement of properties of commercial products. In this study, the potential of the silyl functionalized cellulose nanofibrils (CNF) as a reinforcing additive for the water‐ and solvent‐based two‐component polyurethane (PU) lacquer coatings was evaluated. The addition of the silylated CNF improved the abrasion resistance, strength, and elasticity of the PU coatings. When using the silylated CNF as an additive, the adhesion of the PU coatings was retained. The oxygen permeation rate of the silylated CNF films was strongly influenced by the nature of the solvent. The silylated CNF showed potential as a reinforcing additive even at low loadings in the two‐component PU lacquers. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44801.