bluuebunny/crossref_metadata_2025_split huggingface dataset:
E4‐Butterfly‐Komplexe (E=P, As) als Chelatliganden
Authors: Schwarzmaier Christoph , Heinl Sebastian , Balázs Gábor , Scheer Manfred 
Published: September 2015

AbstractEs wird über die koordinierenden Eigenschaften neuer Typen zweizähniger Phosphan‐ und Arsanliganden mit einem engen Bisswinkel berichtet. Die Reaktionen von [{Cp′′′Fe(CO)2}2(μ,η1:1‐P4)] (1 a) mit dem Kupfersalz [Cu(CH3CN)4][BF4] führt in Abhängigkeit von der Stöchiometrie der Reaktionskomponenten zur Bildung der Spiroverbindung [{{Cp′′′Fe(CO)2}2(μ3,η1:1:1:1‐P4)}2Cu]+[BF4]− (2) oder des Monoaddukts [{Cp′′′Fe(CO)2}2(μ3,η1:1:2‐P4){Cu(MeCN)}]+[BF4]− (3). In ähnlicher Weise reagiert der Arsanligand [{Cp′′′Fe(CO)2}2(μ,η1:1‐As4)] (1 b) mit [Cu(CH3CN)4][BF4] zu [{{Cp′′′Fe(CO)2}2(μ3,η1:1:1:1‐As4)}2Cu]+[BF4]− (5). Die Protonierung von 1 a erfolgt an den “Flügel”‐Phosphoratomen, was in Übereinstimmung mit den Ergebnissen der DFT‐Rechnungen ist. Die Verbindungen wurden mittels spektroskopischer Methoden (heteronukleare NMR‐Spektroskopie und IR‐Spektrometrie) und durch Röntgenbeugung an Einkristallen charakterisiert.
Practical Synthesis of p‐ and o‐Amino‐ and Methoxyphenolic Anthraquinones
Authors: Nicolaou K. C. , Lu Min , Chen Pengxi , Shah Akshay A. 
Published: September 2015

AbstractNew versatile and selective methods for the syntheses of substituted amino‐ and methoxyphenolic anthraquinones (I–IV) based on fusion of cyanophthalides (V) and semiquinone aminals (VI, VII) under basic conditions are described.
Two‐Dimensional Boron Monolayers Mediated by Metal Substrates
Authors: Zhang Zhuhua , Yang Yang , Gao Guoying , Yakobson Boris I. 
Published: September 2015

AbstractTwo‐dimensional (2D) materials, such as graphene and boron nitride, have specific lattice structures independent of external conditions. In contrast, the structure of 2D boron sensitively depends on metal substrate, as we show herein using the cluster expansion method and a newly developed surface structure‐search method, both based on first‐principles calculations. The preferred 2D boron on weaker interacting Au is nonplanar with significant buckling and numerous polymorphs as in vacuum, whereas on more reactive Ag, Cu, and Ni, the polymorphic energy degeneracy is lifted and a particular planar structure is found to be most stable. We also show that a layer composed of icosahedral B12 is unfavorable on Cu and Ni but unexpectedly becomes a possible minimum on Au and Ag. The substrate‐dependent 2D boron choices originate from a competition between the strain energy of buckling and chemical energy of electronic hybridization between boron and metal.
Copper‐Catalyzed Enantioselective 1,6‐Boration of para‐Quinone Methides and Efficient Transformation of gem‐Diarylmethine Boronates to Triarylmethanes
Authors: Lou Yazhou , Cao Peng , Jia Tao , Zhang Yongling , Wang Min , Liao Jian 
Published: September 2015

AbstractPresented is the first enantioselective copper‐catalyzed 1,6‐conjugate addition of bis(pinacolato)diboron to para‐quinone methides. The reaction proceeds with excellent yields and good to excellent enantioselectivities, and provides an attractive approach to the construction of optically active gem‐diarylmehtine boronic esters. Additionally, the subsequent conversion of the derived potassium trifluoroborates into triarylmethanes with highly enantiospecificity was realized.
Total Synthesis of (+)‐Rubriflordilactone A
Authors: Goh Shermin S. , Chaubet Guilhem , Gockel Birgit , Cordonnier Marie‐Caroline A. , Baars Hannah , Phillips Andrew W. , Anderson Edward A. 
Published: September 2015

AbstractTwo enantioselective total syntheses of the nortriterpenoid natural product rubriflordilactone A are described, which use palladium‐ or cobalt‐catalyzed cyclizations to form the CDE rings, and converge on a late‐stage synthetic intermediate. These key processes are set up through the convergent coupling of a common diyne component with appropriate AB‐ring aldehydes, a strategy that sets the stage for the synthetic exploration of other members of this family of natural products.
Belt‐Shaped Cyclonaphthylenes
Authors: Sun Zhe , Sarkar Parantap , Suenaga Takuya , Sato Sota , Isobe Hiroyuki 
Published: September 2015

AbstractThe recent development of cyclo‐para‐phenylenes has demonstrated the feasibility of radial π systems in nanohoop structures, especially in the crystalline state. However, in contrast to macrocyclic molecules with benzene units, which have a several‐decades‐long history, macrocycles composed solely of naphthylene units (the smallest acene) have been much less explored. Although two examples of cyclonaphthylenes have been reported to date, neither possesses a radial π system. We herein report the first example of belt‐shaped cyclonaphthylenes with curved π systems. The molecule, [8]cyclo‐amphi‐naphthylene, is linked at the 2,6‐positions of the naphthylene units, thus affording belt‐shaped molecules. Although the molecular structures are flexible, which allows for rotation of the naphthylene units in solution, they can be rigidified with the aid of methylene bridges to afford persistent molecular structures in solution.
Reversible Size Control of Liquid‐Metal Nanoparticles under Ultrasonication
Authors: Yamaguchi Akihisa , Mashima Yu , Iyoda Tomokazu 
Published: September 2015

AbstractThis paper describes the reversible control of the size of liquid‐metal nanoparticles under ultrasonication. Gallium was utilized as a liquid metal, which has a melting point of 29.8 °C. Investigating the effects of ultrasonication (power, time, and temperature) on the formation of gallium nanoparticles revealed that the process is similar to the formation of oil in water (O/W) or water in oil (W/O) emulsions, as the temperature significantly affects the size of the gallium nanoparticles (GaNPs). Under ultrasonication, the balance between the break‐up and coalescence of the GaNPs can be adjusted by changing the temperature or adding acid through modulating the natural surface oxide layer (which can be removed with acid) and the stabilizing effect of the surfactant dodecanethiol. Coalescence was predominant at higher temperatures, whereas particle break‐up was found to be predominant at lower temperatures. Furthermore, the change in size was accompanied by a shift in the plasmonic absorption of the GaNPs in the UV region.
Probing the Catalytic Promiscuity of a Regio‐ and Stereospecific C‐Glycosyltransferase from Mangifera indica
Authors: Chen Dawei , Chen Ridao , Wang Ruishan , Li Jianhua , Xie Kebo , Bian Chuancai , Sun Lili , Zhang Xiaolin , Liu Jimei , Yang Lin , Ye Fei , Yu Xiaoming , Dai Jungui 
Published: September 2015

AbstractThe catalytic promiscuity of the novel benzophenone C‐glycosyltransferase, MiCGT, which is involved in the biosynthesis of mangiferin from Mangifera indica, was explored. MiCGT exhibited a robust capability to regio‐ and stereospecific C‐glycosylation of 35 structurally diverse druglike scaffolds and simple phenolics with UDP‐glucose, and also formed O‐ and N‐glycosides. Moreover, MiCGT was able to generate C‐xylosides with UDP‐xylose. The OGT‐reversibility of MiCGT was also exploited to generate C‐glucosides with simple sugar donor. Three aryl‐C‐glycosides exhibited potent SGLT2 inhibitory activities with IC50 values of 2.6×, 7.6×, and 7.6×10−7 M, respectively. These findings demonstrate for the first time the significant potential of an enzymatic approach to diversification through C‐glycosidation of bioactive natural and unnatural products in drug discovery.
E4 Butterfly Complexes (E=P, As) as Chelating Ligands
Authors: Schwarzmaier Christoph , Heinl Sebastian , Balázs Gábor , Scheer Manfred 
Published: September 2015

AbstractThe coordination properties of new types of bidentate phosphane and arsane ligands with a narrow bite angle are reported. The reactions of [{Cp′′′Fe(CO)2}2(μ,η1:1‐P4)] (1 a) with the copper salt [Cu(CH3CN)4][BF4] leads, depending on the stoichiometry, to the formation of the spiro compound [{{Cp′′′Fe(CO)2}2(μ3,η1:1:1:1‐P4)}2Cu]+[BF4]− (2) or the monoadduct [{Cp′′′Fe(CO)2}2(μ3,η1:1:2‐P4){Cu(MeCN)}]+[BF4]− (3). Similarly, the arsane ligand [{Cp′′′Fe(CO)2}2(μ,η1:1‐As4)] (1 b) reacts with [Cu(CH3CN)4][BF4] to give [{{Cp′′′Fe(CO)2}2(μ3,η1:1:1:1‐As4)}2Cu]+[BF4]− (5). Protonation of 1 a occurs at the “wing tip” phosphorus atoms, which is in line with the results of DFT calculations. The compounds are characterized by spectroscopic methods (heteronuclear NMR spectroscopy and IR spectrometry) and by single‐crystal X‐ray diffraction studies.
Depolymerization protocol for linear, branched, and crosslinked end‐of‐life silicones with boron trifluoride diethyl etherate as the depolymerization reagent
Authors: Döhlert Peter , Enthaler Stephan 
Published: September 2015

ABSTRACTAn important issue for current society is the accumulation of large amounts of end‐of‐life polymers, which are mainly deposited in landfills, converted by thermal recycling or down cycling to low‐quality materials. In contrast to that, the feedstock recycling of end‐of‐life polymers to produce new high‐quality polymers is only applied to a small portion of waste. In more detail, low‐molecular weight chemicals are generated by this methodology; they can be polymerized in a second step to produce new high‐quality polymers. Notably, with these depolymerization‐polymerization processes, contributions to a more sustainable, resource‐conserving, and environmentally benign society can be made. In this regard, we have set up a capable protocol for the depolymerization of polysiloxanes, which are applied extensively in numerous technological applications. Boron trifluoride diethyl etherate was used as a depolymerization reagent to transform SiO bonds in linear, branched, and crosslinked silicones to SiF bonds. As depolymerization products, difluorodimethyl silane for linear polysiloxanes and methyl trifluorosilane for branched polysiloxanes were obtained; these were suitable synthons for new polymers and will allow an overall recycling of polysiloxanes. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42814.
Influence of the solvent and nonsolvent composition on the electrospinning of a cellulose acetate ternary system
Authors: Korehei Reza , Olson James , Ko Frank , Kadla John 
Published: September 2015

ABSTRACTA series of cellulose acetate (CA) ternary system solutions consisting of the CA, N,N‐dimethylacetamide, and various nonsolvents, such as 1‐propanol, 1‐hexanol, 1‐octanol, 1‐decanol, 1,3‐propane diol, and glycerol, were prepared, and the effects of the component composition on the solutions characteristics and electrospinning were examined. In particular, the effects of the nonsolvent concentration, structure, and degree of miscibility with other components were studied. In some cases, increasing the nonsolvent content increased the solution viscosity and facilitated the electrospinning process. However, we found that electrospinning was also governed by the structure of the nonsolvents and by the solution viscosity. An increase in the number of hydroxyl groups or an increase in the hydrocarbon chain length of the monohydroxyl alcohol nonsolvent improved the fiber formation. The calculated Hansen sphere [D(S‐p)] values of the CA ternary system solution were then used to explain their electrospinnability. The increases in the hydrophilicity and hydrophobicity of system caused by changes in the nonsolvent structure increased the D(S‐p) values and improved fiber formation in electrospinning process. The calculated D(S‐p) values were also shown to be in good agreement with the obtained microscopy images of the electrospun fiber. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42819.
Interfacial encapsulation of bio‐based benzoxazines in epoxy shells for temperature triggered healing
Authors: Sharma Pratibha , Lochab Bimlesh , Kumar Devendra , Roy Prasun Kumar 
Published: September 2015

ABSTRACTSuccessful application of interfacial engineering for the preparation of cross‐linked epoxy microspheres containing thermally polymerizable cardanol‐based benzoxazine (Bz‐C) monomer in the core is demonstrated. Bz‐C is facilely synthesized by Mannich type condensation of cardanol (a by‐product of cashew nut industry) and aniline with formaldehyde under solventless conditions. The encapsulation process relies on the preferential reaction of polydimethylsiloxane immiscible epoxy resin and amine‐based hardener to form a cross‐linked spherical shell at the interface. The microcapsule dimensions and core content could be tailored by modulating the operating parameters, particularly stirring speed and Bz‐C: epoxy ratio. Spherical microcapsules with a core content of ∼37% were obtained when the reaction was carried out at 600 rpm, while maintaining the reaction medium at 70°C with Bz‐C: epoxy ratio of 2.3 : 1. The simplicity and versatility of the present methodology are the forte of this technique, which widens the scope for large‐scale application of benzoxazines in the field of temperature triggered healing. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42832.
Dielectric and optical properties of a poly(ethylene terephthalate) membrane in the temperature interval 150–400 K
Authors: Maletic Slavica B. , Cerovic Dragana D. , Marinkovic Filip S. , Dojcilovic Jablan R. 
Published: September 2015

ABSTRACTIn this study, the dielectric and optical properties of poly(ethylene terephthalate) (PET) membranes were examined. The dielectric measurements were carried out in the temperature interval 150–400 K and in the frequency range 20 Hz–60 kHz. We analyzed in detail the temperature dependences of the dielectric permittivity and dielectric loss (tan δ) at various test frequencies. The relaxation tan δ peak, which appeared in the temperature range 150–300 K, was identified as the secondary β relaxation. The increase in tan δ at temperatures higher than 300 K could be explained as approaching the α relaxation. Optical measurements were performed in the UV–visible region from 200 to 400 nm at various temperatures between 150 and 400 K. The values of the direct and indirect band gaps were calculated at various temperatures. These values were lower for higher temperatures. An absorption peak was observed at a wavelength around of 285 nm at temperatures lower than 300 K. Such insight into the dielectric and optical responses of PET track membranes in a wide temperature range is particularly important when this material is used as a matrix for the semiconductor structure in the development of optoelectronic or microfluid devices. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42834.
Construction of a horseradish peroxidase resistant toward hydrogen peroxide by saturation mutagenesis
Authors: Asad Sedigheh , Dastgheib Seyed Mohammad Mehdi , Khajeh Khosro 
Published: September 2015

AbstractHorseradish peroxidase (HRP) with a variety of potential biotechnological applications is still isolated from the horseradish root as a mixture of different isoenzymes with different biochemical properties. There is an increasing demand for preparations of high amounts of pure enzyme but its recombinant production is limited because of the lack of glycosylation in Escherichia coli and different glycosylation patterns in yeasts which affects its stability parameters. The goal of this study was to increase the stability of non‐glycosylated enzyme, which is produced in E. coli, toward hydrogen peroxide via mutagenesis. Asparagine 268, one of the N‐glycosylation sites of the enzyme, has been mutated via saturation mutagenesis using the megaprimer method. Modification and miniaturization of previously described protocols enabled screening of a library propagated in E. coli XJb (DE3). The library of mutants was screened for stability toward hydrogen peroxide with azinobis (ethylbenzthiazoline sulfonate) as a reducing substrate. Asn268Gly mutant, the top variant from the screening, exhibited 18‐fold increased stability toward hydrogen peroxide and twice improved thermal stability compared with the recombinant HRP. Moreover, the substitution led to 2.5‐fold improvement in the catalytic efficiency with phenol/4‐aminoantipyrine. Constructed mutant represents a stable biocatalyst, which may find use in medical diagnostics, biosensing, and bioprocesses.
Racial disparities in heterotaxy syndrome
Authors: Lopez Keila N. , Marengo Lisa K. , Canfield Mark A. , Belmont John W. , Dickerson Heather A. 
Published: September 2015

BackgroundHeterotaxy syndrome (HTX) is a constellation of defects including abnormal organ lateralization and often including congenital heart defects. HTX has widely divergent population‐based estimates of prevalence, racial and ethnic predominance, and mortality in current literature.MethodsThe objective of this study was to use a population‐based registry to investigate potential racial and ethnic disparities in HTX. Using the Texas Birth Defects Registry, we described clinical features and mortality of HTX among infants delivered from 1999 to 2006. We calculated birth prevalence and crude prevalence (cPR) ratios for infant sex, maternal diabetes, and sociodemographic factors.ResultsA total of 353 HTX cases were identified from 2,993,604 births (prevalence ratio = 1.18 per 10,000 live births. HTX prevalence was approximately 70% higher among infants of Hispanic and non‐Hispanic black mothers and 28% higher among female infants (cPR = 1.28; 95% confidence interval,1.04–1.59). There was a twofold higher female preponderance for infants of mothers who were non‐Hispanic white or black. Mothers with diabetes were three times more likely to have a child with HTX compared with nondiabetics (cPR = 3.13; 95% confidence interval, 2.12–4.45). Among nondiabetics, HTX cases were 86% more likely to have a Hispanic mother and 72% a non‐Hispanic black mother. First‐year mortality for live born children with HTX was 30.9%.ConclusionThis study represents one of the largest population‐based studies of HTX to date, with a novel finding of higher rates of HTX among Hispanic infants of mostly Mexican origin, as well as among female infants of only non‐Hispanic white and black mothers. These findings warrant further investigation.Birth Defects Research (Part A), 2015. © 2015 Wiley Periodicals, Inc. Birth Defects Research (Part A) 103:941–950, 2015. © 2015 Wiley Periodicals, Inc.
Digitale Ermittlung von Rissweite und Rissaufweitungsgeschwindigkeit
Authors: Kley Christina , Mark Peter 
Published: September 2015

AbstractSpröde Versagensformen, wie das Versagen querkraftunbewehrter Bauteile, sind nur schwer prognostizierbar. Allerdings kann das beginnende Versagen infolge Querkraft durch die Bildung von Schubrissen charakterisiert werden. Vergleicht man die Schubrissweite zu einer bestimmten Last, so zeigen sich im Versuch bei geringer querkraftbewehrten Balken deutlich größere Rissweiten. Die Beobachtung der Aufweitung des initialen Schubrisses beinhaltet folglich ein Potenzial zur Ableitung eines Bewertungskriteriums für die Art des sich einstellenden Schubversagens.Im Beitrag wird ein Verfahren zur kontinuierlichen Nachverfolgung der Rissaufweitung anhand einer digitalen Bildanalyse und dessen Anwendung vorgestellt. Der aufgehende Schubriss wird dafür mit einer konventionellen Spiegelreflexkamera in vorgegebenem Intervall während des Belastungsversuchs fotografiert. Zur Rissidentifizierung werden Segmentierungsverfahren aus der Bildverarbeitung kombiniert und ein Binärbild erzeugt, in dem gerissene Bereiche weiß erscheinen. Bei bekannter Auflösung kann anhand der Rissanteile auf die Rissweite geschlossen werden.Digital detection of crack width and crack widening velocityUp to now a sound criterion to assess the type of shear failure of reinforced concrete structures precisely is lacking. Comparing the shear crack widths of common single span concrete beams of different reinforcement ratios at an equal load level, low reinforced beams show significantly wider cracks. In cases of highly shear reinforced beams a moderate crack widening velocity comes allong with load increase while low shear reinforced beams possess an accelerated crack widening velocity accompanied by a minor load increase. Hence, investigation of the crack widening velocity holds potential to derive criteria to judge the expected brittleness of shear failure. In a first step to determine the crack width, digital images are continuously taken at predetermined time instants from concrete specimen and are analysed using mathematical software. Monitoring a predefined region in known size, the crack width is gained counting picture elements which are belonging to the crack. Employing digital image processing, the picture matrix is converted into a binary one where cracked areas appear white and uncracked black. The contribution introduces the main concept and first results of the evaluation routine applied to laboratory tests.
Arsenic remediation by formation of arsenic sulfide minerals in a continuous anaerobic bioreactor
Authors: Rodriguez‐Freire Lucia , Moore Sarah E. , Sierra‐Alvarez Reyes , Root Robert A. , Chorover Jon , Field James A. 
Published: September 2015

ABSTRACTArsenic (As) is a highly toxic metalloid that has been identified at high concentrations in groundwater in certain locations around the world. Concurrent microbial reduction of arsenate (AsV) and sulfate (SO42−) can result in the formation of poorly soluble arsenic sulfide minerals (ASM). The objective of this research was to study As biomineralization in a minimal iron environment for the bioremediation of As‐contaminated groundwater using simultaneous AsV and SO42− reduction. A continuous‐flow anaerobic bioreactor was maintained at slightly acidic pH (6.25–6.50) and fed with AsV and SO42−, utilizing ethanol as an electron donor for over 250 d. A second bioreactor running under the same conditions but lacking SO42− was operated as a control to study the fate of As (without S). The reactor fed with SO42− removed an average 91.2% of the total soluble As at volumetric rates up to 2.9 mg As/(L · h), while less than 5% removal was observed in the control bioreactor. Soluble S removal occurred with an S to As molar ratio of 1.2, suggesting the formation of a mixture of orpiment‐ (As2S3) and realgar‐like (AsS) solid phases. Solid phase characterization using K‐edge X‐ray absorption spectroscopy confirmed the formation of a mixture of As2S3 and AsS. These results indicate that a bioremediation process relying on the addition of a simple, low‐cost electron donor offers potential to promote the removal of As from groundwater with naturally occurring or added SO42− by precipitation of ASM. Biotechnol. Bioeng. 2016;113: 522–530. © 2015 Wiley Periodicals, Inc.