bluuebunny/crossref_metadata_2025 huggingface dataset:
Biomimetic Total Syntheses of (−)‐Leucoridines A and C through the Dimerization of (−)‐Dihydrovalparicine
Authors: Kokkonda Praveen , Brown Keaon R. , Seguin Trevor J. , Wheeler Steven E. , Vaddypally Shivaiah , Zdilla Michael J. , Andrade Rodrigo B.
Published: September 2015

Concise biomimetic syntheses of the Strychnos‐Strychnos‐type bis‐indole alkaloids (−)‐leucoridine A (1) and C (2) were accomplished through the biomimetic dimerization of (−)‐dihydrovalparicine (3). En route to 3, the known alkaloids (+)‐geissoschizoline (8) and (−)‐dehydrogeissoschizoline (10) were also prepared. DFT calculations were employed to elucidate the mechanism, which favors a stepwise aza‐Michael/spirocyclization sequence over the alternate hetero‐Diels–Alder cycloaddition reaction.
The Instability of Ni{N(SiMe3)2}2: A Fifty Year Old Transition Metal Silylamide Mystery
Authors: Faust Michelle , Bryan Aimee M. , Mansikkamäki Akseli , Vasko Petra , Olmstead Marilyn M. , Tuononen Heikki M. , Grandjean Fernande , Long Gary J. , Power Philip P.
Published: September 2015

The characterization of the unstable NiII bis(silylamide) Ni{N(SiMe3)2}2 (1), its THF complex Ni{N(SiMe3)2}2(THF) (2), and the stable bis(pyridine) derivative trans‐Ni{N(SiMe3)2}2(py)2 (3), is described. Both 1 and 2 decompose at ca. 25 °C to a tetrameric NiI species, [Ni{N(SiMe3)2}]4 (4), also obtainable from LiN(SiMe3)2 and NiCl2(DME). Experimental and computational data indicate that the instability of 1 is likely due to ease of reduction of NiII to NiI and the stabilization of 4 through dispersion forces.
Direct X‐Ray Scattering Evidence for Metal–Metal Interactions in Solution at the Molecular Level
Authors: Cebollada Andrea , Vellé Alba , Iglesias Manuel , Fullmer Lauren B. , Goberna‐Ferrón Sara , Nyman May , Sanz Miguel Pablo J.
Published: September 2015

The study of the aggregation of small molecules in solution induced by metallophilic interactions has been traditionally performed by spectroscopic methods through identification of chemical changes in the system. Herein we demonstrate the use of SAXS (small‐angle X‐ray scattering) to identify structures in solution, taking advantage of the excellent scattering intensity of heavy metals which have undergone association by metallophilic interactions. An analysis of the close relationship between solid‐state and solution arrangements of a dynamic [Ag2(bisNHC)2]2+ (NHC=N‐heterocyclic carbene) system, and how they are complementary to each other, is reported.
Enzymatic Prenylation and Oxime Ligation for the Synthesis of Stable and Homogeneous Protein–Drug Conjugates for Targeted Therapy
Authors: Lee Joong‐jae , Choi Hyo‐Jung , Yun Misun , Kang YingJin , Jung Ji‐Eun , Ryu Yiseul , Kim Tae Yoon , Cha Young‐je , Cho Hyun‐Soo , Min Jung‐Joon , Chung Chul‐Woong , Kim Hak‐Sung
Published: September 2015

Targeted therapy based on protein–drug conjugates has attracted significant attention owing to its high efficacy and low side effects. However, efficient and stable drug conjugation to a protein binder remains a challenge. Herein, a chemoenzymatic method to generate highly stable and homogenous drug conjugates with high efficiency is presented. The approach comprises the insertion of the CaaX sequence at the C‐terminal end of the protein binder, prenylation using farnesyltransferase, and drug conjugation through an oxime ligation reaction. MMAF and an EGFR‐specific repebody are used as the antitumor agent and protein binder, respectively. The method enables the precisely controlled synthesis of repebody–drug conjugates with high yield and homogeneity. The utility of this approach is illustrated by the notable stability of the repebody–drug conjugates in human plasma, negligible off‐target effects, and a remarkable antitumor activity in vivo. The present method can be widely used for generating highly homogeneous and stable PDCs for targeted therapy.
In Situ Electrochemical Synthesis of Oriented and Defect‐Free AEL Molecular‐Sieve Films Using Ionic Liquids
Authors: Yu Tongwen , Chu Wenling , Cai Rui , Liu Yanchun , Yang Weishen
Published: September 2015

Simply preparing oriented and defect‐free molecular‐sieve films have been a long‐standing challenge both in academia and industry. Most of the early works focus on the careful and multiple controls of the seeds layer or synthesis conditions. Herein, we report a one‐step in situ electrochemical ionothermal method that combines a controllable electric field with ionic liquids. We demonstrate that an in‐plane oriented and defect‐free AEL (one molecular‐sieve framework type) molecular‐sieve film was obtained using an Al electrode as the Al source. The excellent corrosion‐resistant performance of the film makes this technology promising in multiple applications, such as anti‐corrosion coatings.
Optogenetic Apoptosis: Light‐Triggered Cell Death
Authors: Hughes Robert M. , Freeman David J. , Lamb Kelsey N. , Pollet Rebecca M. , Smith Weston J. , Lawrence David S.
Published: September 2015

An optogenetic Bax has been designed that facilitates light‐induced apoptosis. We demonstrate that mitochondrial recruitment of a genetically encoded light‐responsive Bax results in the release of mitochondrial proteins, downstream caspase‐3 cleavage, changes in cellular morphology, and ultimately cell death. Mutagenesis of a key phosphorylatable residue or modification of the C‐terminus mitigates background (dark) levels of apoptosis that result from Bax overexpression. The mechanism of optogenetic Bax‐mediated apoptosis was explored using a series of small molecules known to interfere with various steps in programmed cell death. Optogenetic Bax appears to form a mitochondrial apoptosis‐induced channel analogous to that of endogenous Bax.
Autoresolution of Segregated and Mixed p‐n Stacks by Stereoselective Supramolecular Polymerization in Solution
Authors: Narayan Bhawani , Bejagam Karteek K. , Balasubramanian Sundaram , George Subi J.
Published: September 2015

A “chirality driven self‐sorting” strategy is introduced for the controlled supramolecular organization of donor (D) and acceptor (A) molecules in multicomponent assemblies. The trans‐1,2‐bis(amido)cyclohexane (trans‐BAC) has been identified as a supramolecular motif with strong homochiral recognition to direct this chirality controlled assembly process of enantiomers in solution. Stereoselective supramolecular polymerization of trans‐BAC appended naphthalene diimide monomers (NDIs) has been probed in detail by spectroscopic and mechanistic investigations. This chirality‐driven self‐sorting design of enantiomeric components also offers to realize mixed and segregated D‐A stacks by supramolecular co‐assembly of the NDI acceptors with trans‐BAC appended dialkoxynaphthalene (DAN) donor monomers. Such an unprecedented chirality control on D‐A organization paves the way for the creation of supramolecular p‐n nanostructures with controlled molecular‐level organization.
Kinetic Destabilization of Metal–Metal Single Bonds: Isolation of a Pentacoordinate Manganese(0) Monoradical
Authors: Agnew Douglas W. , Moore Curtis E. , Rheingold Arnold L. , Figueroa Joshua S.
Published: September 2015

The 17e− monoradical [Mn(CO)5] is widely recognized as an unstable organometallic transient and is known to dimerize rapidly with the formation of a MnMn single bond. As a result of this instability, isolable analogues of [Mn(CO)5] have remained elusive. Herein, we show that two sterically encumbering isocyanide ligands can destabilize the MnMn bond leading to the formation of the isolable, manganese(0) monoradical [Mn(CO)3(CNArDipp2)2] (ArDipp2=2,6‐(2,6‐(iPr)2C6H3)2C6H3). The persistence of [Mn(CO)3(CNArDipp2)2] has allowed for new insights into nitrosoarene spin‐trapping studies of [Mn(CO)5].
Increased Water Reduction Efficiency of Polyelectrolyte‐Bound Trimetallic [Ru,Rh,Ru] Photocatalysts in Air‐Saturated Aqueous Solutions
Authors: Canterbury Theodore R. , Arachchige Shamindri M. , Moore Robert B. , Brewer Karen J.
Published: September 2015

The groundbreaking use of polyelectrolytes to increase the efficiency of supramolecular photocatalysts in solar H2 production schemes under aqueous aerobic conditions is reported. Supramolecular photocatalysts of the architecture [{(TL)2Ru(BL)}2RhX2]5+ (BL=bridging ligand, TL=terminal ligand, X=halide) demonstrate high efficiencies in deoxygenated organic solvents but do not function in air‐saturated aqueous solution because of the quenching of the metal‐to‐ligand charge‐transfer (MLCT) excited state under these conditions. The new photocatalytic system incorporates poly(4‐styrenesulfonate) (PSS) into aqueous solutions containing [{(bpy)2Ru(dpp)}2RhCl2]5+ (bpy=2,2′‐bipyridine, dpp=2,3‐bis(2‐pyridyl)pyrazine). PSS has a profound impact on the photocatalyst efficiency, increasing H2 production over three times that of deoxygenated aqueous solutions alone. H2 photocatalysis proceeds even under aerobic conditions for PSS‐containing solutions, an exciting consequence for solar hydrogen‐production research.
E4‐Butterfly‐Komplexe (E=P, As) als Chelatliganden
Authors: Schwarzmaier Christoph , Heinl Sebastian , Balázs Gábor , Scheer Manfred
Published: September 2015

Es 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

New 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

Two‐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

Presented 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

Two 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

The 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

This 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

The 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

The 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.
Synthesis, structural characterization, density functional theory calculations and biological evaluation of a new organotin(IV) complex containing N‐isonicotinyl‐N',N″‐diaryl phosphorictriamide as N‐donor ligand
Authors: Gholivand Khodayar , Rajabi Maryam , Dorosti Niloufar , Molaei Foroogh
Published: September 2015

A new diorganotin(IV) complex with the formula SnCl2(CH3)2L2 (C1a), L = 4‐NC5H4CONHPO(NCH3CH2C6H5)2, was synthesized and characterized using 1H NMR, 13C NMR, 31P NMR, 119Sn NMR and infrared spectroscopies. The molecular structure of C1a was determined using X‐ray crystallography, revealing that C1a contains hexa‐coordinated Sn(IV) centres with trans‐configuration of donor atoms around them. Each Sn(IV) atom is positioned in the centre of inversion of an octahedron. C1a forms one‐dimensional chains via two equal intermolecular PO…HN hydrogen bonds. These hydrogen bonds produce centrosymmetric rings as a supramolecular hydrogen‐bonded pattern. In order to compare the relative stability of C1a (with N‐ligated configuration) and its possible O‐ligated isomer, C1b, density functional theory calculations were performed, the results showing a preference of C1a over C1b from an energy point of view. Also, natural bond orbital analysis was carried out to obtain detailed information on the electronic features of the optimized structures. The theoretical results show that intermolecular hydrogen bonding in the crystal structure has a significant role in the stabilization of C1a, and Sn(IV) interacts more strongly with the Npy atom than the PO functional group. Furthermore, the free ligand and its complex were tested against three human cancer cell lines, i.e. human cervical carcinoma (HeLa), human prostate cancer (PC‐3) and human breast adenocarcinoma cancer (MCF‐7). C1a displays moderate to good cytotoxicity towards all three cancer cell lines. Moreover, antibacterial tests were carried out using the disc‐diffusion method, in which C1a shows high activity against selected Gram‐negative and Gram‐positive bacteria. Copyright © 2015 John Wiley & Sons, Ltd.
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

An 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

A 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

Successful 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

In 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

Horseradish 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

Background

Heterotaxy 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.

Methods

The 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.

Results

A 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%.

Conclusion

This 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

Spröde 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 velocity

Up 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

Arsenic (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.
Human papillomavirus infection in the oromaxillofacial area: Clinical anatomy and histological considerations
Authors: Ilea Aranka , Boşca Bianca , MiclĂuş Viorel , Rus Vasile , BĂbţan Anida Maria , CÂmpian Radu Septimiu
Published: September 2015

Clinical manifestations of human papillomavirus (HPV) infection in the head and neck can range from benign lesions, which are the most frequent, to malignant lesions. The prevalence of head and neck cancer is increasing, despite currently decreasing trends in known risk factors such as smoking and alcohol use. A new patient profile has appeared in recent practice: most frequently a middle‐aged male patient who does not smoke or drink alcohol, is sexually active (possibly having multiple partners), and presents with oral or cervicofacial lesions requiring diagnosis and treatment. Another risk factor that should be considered in these patients is HPV infection. The association of oral potentially malignant disorders (OPMD) with HPV is a challenge for the medical practitioner. The gold standard for diagnosis is histopathological examination, which can also yield evidence suggesting HPV infection. Determination of the viral genotype provides additional data for assessing the oncological risk of an HPV infection. Treatment of these patients is aimed at removing the lesions, in association or not with antiviral treatment and recurrence control. Clin. Anat. 28:1002–1007, 2015. © 2015 Wiley Periodicals, Inc.
A National Initiative of Teaching, Researching, and Dreaming: Community College Faculty Research in “Achieving the Dream” Colleges
Authors: Hagedorn Linda Serra
Published: September 2015

Dating back to 2004, the Achieving the Dream initiative was established to promote evidence‐based programs and interventions to produce and sustain student success. Achieving the Dream has created a new environment and new forms of thinking among the faculty that have spurred some to action research within their classrooms and beyond. Using three vignettes, this chapter presents how the Achieving the Dream initiative has fostered faculty research.
Gender differences in acute and 30‐day outcomes after orbital atherectomy treatment of de novo, severely calcified coronary lesions
Authors: Kim Christopher Y. , Lee Arthur C. , Wiedenbeck Troy L. , Lee Michael S. , Chambers Jeff W.
Published: September 2015

Objectives

The aim of this analysis is to evaluate potential differences according to gender in terms of acute and 30‐day clinical outcomes in patients enrolled in the ORBIT II trial with de novo, severely calcified coronary lesions treated with orbital atherectomy to facilitate stent delivery.

Background

Previous studies have shown an increased risk of safety events in females compared to males undergoing percutaneous coronary intervention.

Methods

ORBIT II, a prospective, nonrandomized, multicenter, single arm study conducted in the US evaluated the safety and efficacy of the coronary OAS to facilitate stent placement in de novo, severely calcified coronary lesions in 443 subjects (286 males and 157 females). The rate of major adverse cardiac events (MACE) defined as a composite of myocardial infarction, target vessel revascularization, and cardiac death was evaluated in‐hospital and 30‐days postprocedure. For this analysis, the ORBIT II safety and efficacy results were stratified by gender.

Results

At baseline, females were significantly older than males and had a lower mean estimated glomerular filtration rate. Males had a higher rate of previous coronary artery bypass grafting and history of smoking. The rates of successful stent delivery and <50% residual stenosis were similar in males and females. In‐hospital and 30‐day MACE rates did not differ by gender.

Conclusions

Despite females being older, having smaller arteries, and more renal dysfunction, preparation of severely calcified coronary lesions with orbital atherectomy to facilitate stent deployment results in similar rates of in‐hospital and 30‐day MACE, irrespective of gender. © 2015 Wiley Periodicals, Inc.
Decatungstate‐Photocatalyzed Si−H/C−H Activation in Silyl Hydrides: Hydrosilylation of Electron‐Poor Alkenes
Authors: Qrareya Hisham , Dondi Daniele , Ravelli Davide , Fagnoni Maurizio
Published: September 2015

Tetrabutylammonium decatungstate has been used for the photocatalytic activation of the Si−H bond in trisubstituted silanes and applied for the hydrosilylation of electron‐poor alkenes. The mechanism that occurs depends on the silyl hydride used, as supported by laser flash photolysis and EPR trapping experiments. Homolytic Si−H cleavage through a hydrogen atom transfer from the silane to the excited catalyst operates with dimethylphenylsilane and methyldiphenylsilane, for which the hydrosilylation yields were satisfactory. If we used tertiary silanes that have more labile Si−H bonds, such as triphenylsilane or tris(trimethylsilyl)silane, the reaction worked to some extent even under uncatalyzed conditions because of a radical chain reaction. Competition between C−H and Si−H cleavage was observed, however, if we used trialkylsilanes (e.g., triethylsilane). In favorable cases, the process was also efficient under flow conditions or if promoted by sunlight.
Copper Nanoparticles Stabilized in a Porous Chitosan Aerogel as a Heterogeneous Catalyst for C−S Cross‐coupling
Authors: Frindy Sana , el Kadib Abdelkrim , Lahcini Mohamed , Primo Ana , García Hermenegildo
Published: September 2015

Cu nanoparticles (NPs) embedded into chitosan fibrils act as a heterogeneous catalyst for the C−S coupling of aryl halides and thiophenol in toluene. The catalyst can be reused under optimal conditions with some activity decrease from the first to the second use. Characterization of the reused catalyst shows that Cu NPs do not undergo agglomeration. Cu‐chitosan is more active for aryl iodides than aryl bromides and chlorides. The presence of chitosan in a large excess is detrimental for the catalytic activity, probably because of the increase of solvent viscosity. It was found that halides formed as byproducts in the reaction act as a catalyst poison and may influence the extent of Cu leaching.
An Intersectional Social Capital Model of Career Development for International Marriage Immigrants
Authors: Kang Hyoun Ju , Callahan Jamie L. , Anne Mrudula
Published: September 2015

The phenomenon of women immigrating to marry has resulted in changing labor markets and increasing workforce diversity. However, because of a lack of social capital in their new country, immigrant women face significant barriers to gaining employment, have access to only limited work arenas, or remain at home as housewives. Existing studies of immigrant women are mainly limited to their human rights or cultural issues; there are few studies focusing on career development for them. This article uses social capital and intersectionality theories to create an intersectional social capital model of career development for immigrant women. The application of the model is explicated through the context of South Korea. The positive career development interventions as described in the model can help immigrant brides overcome multiple career‐related barriers and find new roots.
On the implementation of spatial constraints in multivariate curve resolution alternating least squares for hyperspectral image analysis
Authors: Hugelier Siewert , Devos Olivier , Ruckebusch Cyril
Published: September 2015

Hyperspectral imaging (HSI) is a method for exploring spatial and spectral information associated with the distribution of the different compounds in a chemical or biological sample. Amongst the multivariate image analysis tools utilized to decompose the raw data into a bilinear model, multivariate curve resolution alternating least squares (MCR‐ALS) can be applied to obtain the distribution maps and pure spectra of the components of the sample image. However, a requirement is to have the data in a two‐way matrix. Thus, a preliminary step consists of unfolding the raw HSI data into a single‐pixel direction. Consequently, through this data manipulation, the information regarding pixel neighboring is lost, and spatial information cannot directly be constrained on the component profiles in the current MCR‐ALS algorithm. In this short communication, we propose an adaptation of the MCR‐ALS framework, enabling the potential implementation of any variation of spatial constraint. This can be achieved by adding, at each least‐squares step, refolding/unfolding of the distribution maps for the components. The implementation of segmentation, shape smoothness, and image modeling as spatial constraints is proposed as a proof of concept. Copyright © 2015 John Wiley & Sons, Ltd.
Water Oxidation Catalysis by Synthetic Manganese Oxides with Different Structural Motifs: A Comparative Study
Authors: Frey Carolin E. , Kurz Philipp
Published: September 2015

Manganese oxides are considered to be very promising materials for water oxidation catalysis (WOC), but the structural parameters influencing their catalytic activity have so far not been clearly identified. For this study, a dozen manganese oxides (MnOx) with various solid‐state structures were synthesised and carefully characterised by various physical and chemical methods. WOC by the different MnOx was then investigated with Ce4+ as chemical oxidant. Oxides with layered structures (birnessites) and those containing large tunnels (todorokites) clearly gave the best results with reaction rates exceeding 1250 ${{\rm{mmol}}_{{\rm{O}}_{\rm{2}} } }$ ${{\rm{mol}}_{{\rm{Mn}}}^{ - 1} }$ h−1 or about 50 μmolO2 m−2 h−1. In comparison, catalytic rates per mole of Mn of oxides characterised by well‐defined 3D networks were rather low (e.g., ca. 90 ${{\rm{mmol}}_{{\rm{O}}_{\rm{2}} } }$ ${{\rm{mol}}_{{\rm{Mn}}}^{ - 1} }$ h−1 for bixbyite, Mn2O3), but impressive if normalised per unit surface area (>100 ${{\rm{{\rm \mu} mol}}_{{\rm{O}}_{\rm{2}} } }$ m−2 h−1 for marokite, CaMn2O4). Thus, two groups of MnOx emerge from this screening as hot candidates for manganese‐based WOC materials: 1) amorphous oxides with tunnelled structures and the well‐established layered oxides; 2) crystalline MnIII oxides. However, synthetic methods to increase surface areas must be developed for the latter to obtain good catalysis rates per mole of Mn or per unit catalyst mass.
Robust Ordered Bundles of Porous Helical Nanotubes Assembled from Fully Rigid Ionic Benzene‐1,3,5‐tricarboxamides
Authors: Wu Xibo , Wang Daoliang , Chen Mingming , Wei Chengsha , Wei Shenghui , Huang Ningdong , Li Liangbin , Zhang Guobing
Published: September 2015

Size‐controlled and ordered assemblies of artificial nanotubes are promising for practical applications; however, the supramolecular assembly of such systems remains challenging. A novel strategy is proposed that can be used to reinforce intermolecular noncovalent interactions to construct hierarchical supramolecular structures with fixed sizes and long‐range ordering by introducing ionic terminals and fully rigid arms into benzene‐1,3,5‐tricarboxamide (BTA) molecules. A series of similar BTA molecules with distinct terminal groups and arm lengths are synthesized; all form hexagonal bundles of helical rosette nanotubes spontaneously in water. Despite differences in molecular packing, the dimensions and bundling of the supramolecular nanotubes show almost identical concentration dependence for all molecules. The similarities of the hierarchical assemblies, which tolerate certain molecular irregularities, can extend to properties such as the void ratio of the nanotubular wall. This is a rational strategy that can be used to achieve supramolecular nanotubes in aqueous environments with precise size and ordering at the same time as allowing molecular modifications for functionality.
Controlled Chemical Derivatisation of Carbon Nanotubes with Imaging, Targeting, and Therapeutic Capabilities
Authors: Ménard‐Moyon Cécilia , Ali‐Boucetta Hanene , Fabbro Chiara , Chaloin Olivier , Kostarelos Kostas , Bianco Alberto
Published: September 2015

In drug delivery, carbon nanotubes (CNTs) hold a great potential as carriers because of their ability to easily cross biological barriers and be internalised into cells. Their high aspect ratio allows multi‐functionalisation and their development as a multimodal platform for targeted therapy. In this article, we report the controlled covalent derivatisation of triple‐functionalised CNTs with the anticancer drug gemcitabine, folic acid as a targeting ligand and fluorescein as a probe. The anticancer activity of gemcitabine was maintained after covalent grafting onto the CNTs. The functionalised nanotubes were internalised into both folate‐positive and negative cells, suggesting the passive diffusion of CNTs. Overall, our approach is versatile and offers a precise chemical control of the sidewall functionalisation of CNTs and the possibility to manoeuvre the types of functionalities required on the nanotubes for a multimodal therapeutic strategy.
Strongly Coupled Pt–Ni2GeO4 Hybrid Nanostructures as Potential Nanocatalysts for CO Oxidation
Authors: Ge Xin , Wang Xiao , Wang Zhuo , Yao Shuang , Feng Jing , Liu Dapeng , Song Shuyan , Zhang Hongjie
Published: September 2015

A facile and low‐cost method has been developed to successfully fabricate 3D flower‐like and sphere‐like Ni2GeO4 nanostructures with tunable sizes and shapes. It is found that the hard template, polymethyl methacrylate (PMMA) nanopsheres, is essential to the formation of the final products. The as‐prepared nanostructures can serve as an outstanding support for Pt nanoparticles after surface modification with L‐lysine. In the catalytic test of CO oxidation, Pt–Ni2GeO4 nanoflowers exhibited much higher catalytic performance compared with Pt–Ni2GeO4 nanospheres, representing a typical size‐dependent catalytic property.