bluuebunny/crossref_metadata_2025 huggingface dataset:
A Supramolecular Capsule for Reversible Polysulfide Storage/Delivery in Lithium‐Sulfur Batteries
Authors: Xie Jin , Peng Hong‐Jie , Huang Jia‐Qi , Xu Wen‐Tao , Chen Xiang , Zhang Qiang
Published: November 2017

Supramolecular materials, in which small organic molecules are assembled into regular structures by non‐covalent interactions, attract tremendous interests because of their highly tunable functional groups and porous structure. Supramolecular adsorbents are expected to fully expose their abundant adsorptive sites in a dynamic framework. In this contribution, we introduced cucurbit[6]uril as a supramolecular capsule for reversible storage/delivery of mobile polysulfides in lithium‐sulfur (Li‐S) batteries to control undesirable polysulfide shuttle. The Li‐S battery equipped with the supramolecular capsules retains a high Coulombic efficiency and shows a large increase in capacity from 300 to 900 mAh g−1 at a sulfur loading of 4.2 mg cm−2. The implementation of supramolecular capsules offers insights into intricate multi‐electron‐conversion reactions and manifests as an effective and efficient strategy to enhance Li‐S batteries and analogous applications that involve complex transport phenomena and intermediate manipulation.
Asymmetric Synthesis of Less Accessible α‐Tertiary Amines from Alkynyl Z‐Ketimines
Authors: Kano Taichi , Aota Yusuke , Maruoka Keiji
Published: November 2017

A highly stereoselective synthesis of hitherto less accessible chiral α‐tertiary amines with multiple structurally similar linear carbon chains was achieved through chiral auxiliary mediated addition of organolithium reagents to the geometrically well‐controlled alkynyl Z‐ketimines. This stereoselective nucleophilic addition offers a general approach to the asymmetric synthesis of nitrogen‐containing chiral materials.
Enantioselective and Collective Total Syntheses of Xanthanolides
Authors: Feng Juan , Lei Xiaoqiang , Bao Ruiyang , Li Yuanhe , Xiao Chengqian , Hu Lihong , Tang Yefeng
Published: November 2017

An enantioselective synthesis of (+)‐8‐epi‐xanthatin hinging on a chiral phosphoric acid catalyzed tandem allylboration/lactonization reaction is reported. With (+)‐8‐epi‐xanthatin as the precursor, the collective synthesis of a series of synthetically challenging xanthanolides was also accomplished. Among them, xanthipungolide, one of the most complex xanthanolide monomers, was accessed through a bioinspired tandem double‐bond isomerization/6π electronic cyclization/intramolecular Diels–Alder reaction, and pungiolides A, B, D, E, and L–N, a group of xanthanolide dimers, were assembled through a bioinspired Diels–Alder dimerization followed by late‐stage diversification.
Enantiospecific sp2–sp3 Coupling of ortho‐ and para‐Phenols with Secondary and Tertiary Boronic Esters
Authors: Wilson Claire M. , Ganesh Venkataraman , Noble Adam , Aggarwal Varinder K.
Published: November 2017

The coupling of ortho‐ and para‐phenols with secondary and tertiary boronic esters has been explored. In the case of para‐substituted phenols, after reaction of a dilithio phenolate species with a boronic ester, treatment with Ph3BiF2 or Martin's sulfurane gave the coupled product with complete enantiospecificity. The methodology was applied to the synthesis of the broad spectrum antibacterial natural product (−)‐4‐(1,5‐dimethylhex‐4‐enyl)‐2‐methyl phenol. For ortho‐substituted phenols, initial incorporation of a benzotriazole on the phenol oxygen atom was required. Subsequent ortho‐lithiation and borylation gave the coupled product, again with complete stereospecificity.
Synthesis of a novel azaphosphorine flame retardant and its application in epoxy resins
Authors: Liu Chao , Huang Jiamei , Zhu Jihong , Yuan Conghui , Zeng Birong , Chen Guorong , Xu Yiting , Dai Lizong
Published: November 2017

A novel PCN bond containing azaphosphorine, 5‐(4‐hydroxy)anilinomethyl‐1,3‐di(4‐hydroxy)phenyl‐1,3,5‐diazaphosphorinane (ADDPP‐OH), which could be used as both a cocuring agent and a flame‐retarding agent for epoxy resins (EPs), was synthesized from tetrakis(hydroxymethyl)phosphonium sulfate and characterized by FTIR, 1H‐NMR, 13C‐NMR, 31P‐NMR, and so on. Compared with the pure EP, the ADDPP‐OH–EP composites showed increased decomposition temperatures and char yields. When the content of ADDPP‐OH was 10 wt %, the cured EP composite possessed a limiting oxygen index value of 33.7% and passed the V‐0 rating of the UL‐94 test. The mechanical properties of the ADDPP‐OH–EP composites was improved because of the increased crosslinking density. In addition, the morphology of the residual char indicated an intumescent and multiporous structure in the inner space and a compact and continual appearance in the outer layer; this was important in preventing the materials from burning further. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 45721.
Enhancement of electrical and thermal conductivity of polypropylene by graphene nanoplatelets
Authors: Imran Kazi Al , Lou Jianzhong , Shivakumar Kunigal N.
Published: November 2017

One of disadvantages of polymer composites is poor electrical and thermal conductivity. As a first step in this direction, graphene‐modified polypropylene polymer is being developed to improve its electrical and thermal conductivity. Two techniques were investigated: surface coating and extrusion. In the case of coating technique, the percolation threshold was found to be 0.5 wt % of graphene and electrical conductivity of polypropylene increased around 13 log cycles. Coating technique breaks the agglomerations due to magnetic stirring followed by sonication and gives homogeneous graphene‐coated polypropylene pellets. When polymer melts under compression molding, the graphene platelets network formed on the surface of polypropylene pellets as well as through‐the‐thickness of the molded disk, which provide continuous network of graphene. However, in extrusion technique, graphene segregated and did not disperse properly in polypropylene. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 45833.
Effect of amide distribution in polyamide isomers on their melting points
Authors: Coussens Betty , Rulkens Rudy
Published: November 2017

A new insight has been obtained relating the different structures of linear aliphatic homopolyamides to their melting points. A new equation is derived for structures based on monomers with an even number of methylene units. In this equation, the amide distribution along the polymer chain is defined by a newly introduced parameter K which indicates the lowest number of methylene units between adjacent amide groups. For K ≥ 4 a generic empirical relation is defined, describing the observed melting points of these polyamides. The trend in H‐bond densities in the melt obtained by modeling corresponds well with the trend in observed melting points. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 45837.
New all solid‐state polymer electrolyte based on epoxy resin and ionic liquid for high temperature applications
Authors: Oliveira da Silva Luís Carlos , Soares Bluma Guenther
Published: November 2017

Flexible epoxy network loaded with high amount of ionic liquid (IL) 1‐decyl‐3‐methylimidazolium bromide ([DMIM]Br) has been reported by using a mixture of polyol amine as curing agent. The IL presents good electrochemical response even at 170 °C, as no evidence of redox reactions was observed. The incorporation of as high as 50 wt % of this IL within the epoxy matrix resulted in solid and flexible electrolyte with good thermal stability below 180 °C, as measured by thermogravimetric analysis and ionic conductivity of around 10−6 S cm−1 at room temperature and higher than 10−3 S cm−1 at high temperature. This electrolyte presented a prodigious potential for applications in electrochemical devices at high temperature like batteries and supercapacitors, and the flexibility of this solid electrolyte persist at low temperature because of its low glass transition temperature. Furthermore, leakage problems were not observed. Thereby, impedance spectroscopy and cyclic voltammetry were performed to characterize the electrochemical properties. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 45838.
Interfacial modification mechanism of nanocellulose as a compatibilizer for immiscible binary poly(vinyl alcohol)/poly(ethylene oxide) blends
Authors: Yong Cheng , Mei Changtong , Guan Mingjie , Wu Qinglin , Sun Xiuxuan , Xu Bing , Wang Ke
Published: November 2017

We undertook this study to understand reinforcement mechanism of short cellulose nanocrystals (CNCs) and long cellulose nanofibrils (CNFs) as compatibility agents for improving the interfacial miscibility of poly(vinyl alcohol) (PVA) and poly(ethylene oxide) (PEO) blends. The effects of the two cellulose nanofibers on the morphological, mechanical, and thermal properties of the polymer blends were compared systematically. The light transparency, scanning electron microscopy, and Fourier transform infrared results show that nanocellulose between PVA and PEO eliminated the negative effects generated by the immiscible interface through increased hydrogen bonding. Thermogravimetric analysis and differential scanning calorimetry results show that crystalline region reorganization around the interface facilitated the shift of the polymer blends from multiple phases to a homogeneous phase. According to the Halpin‐Kardos and Quali models, we assumed that the potential for repairing the immiscible interface would have a larger effect than the potential of reinforcement. At the same concentration, polymer blends with CNCs showed greater light transparency, strength, modulus, and crystal structure than with those with CNFs. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 45896.
Propolis as an antidegradant and biocidal agent for natural rubber
Authors: Kmiotek Magdalena , Bieliński Dariusz , Piotrowska Małgorzata
Published: November 2017

The numerous applications of polymers in many areas of our lives make it necessary to protect them from aging. Increases in the safety and time of polymer material exploitation demands the application of antidegradants with broad scopes of action. In this study, crude propolis, originating from two geographical regions of Poland, was used to protect peroxide‐cured natural‐rubber vulcanizates filled with silica or carbon black from degradation by oxygen, ozone, and microorganisms. Thermogravimetry analysis confirmed the stability of propolis under the curing conditions. From vulcametric torque measurements and determinations of the mechanical properties, we determined that the incorporation of propolis did not adversely affect the performance of the natural‐rubber vulcanizates. The addition of propolis to the rubber mix made the vulcanizates resistant to thermooxidative and ozone aging and protected them from biodegradation in soil and the action of microorganisms. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 45911.
Thermal and fire behavior of isophorone diisocyanate based polyurethane foams containing conventional flame retardants
Authors: Eceiza I. , Barrio A. , Martín L. , Veganzones M. A. , Fernández‐Berridi M. J. , Irusta L.
Published: November 2017

This work reports on the fire behavior of isophorone diisocyanate‐based polyurethane foams containing different conventional flame retardants (FRs) such as melamine, ammonium polyphosphate, aluminum hydroxide, expandable graphite, and their combinations. The foams were obtained in a laboratory scale and characterized in terms of their morphology, density, thermal stability, and fire behavior. According to atomic force microscopy, the incorporation of FRs decreased the phase separated domain size. The cellular structure of the foams was examined qualitatively by scanning electron microscopy while the quantitative analysis of the surrounding skin was performed by optical microscopy and Image J. The FR containing foams showed more and smaller cells. The thermogravimetric analysis showed that the FRs had no influence in the initial degradation temperature of the foams. However, the obtained residue values were higher than the theoretical ones, indicating that there was some type of interaction between the FRs and the foams. The fire behavior of polyurethane foams was studied by the cone calorimeter and the data showed that the introduction of expandable graphite and combinations of ammonium polyphosphate/melamine to the reference foam gave rise to a significant reduction in the total heat release. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 45944.
Removal of textile dyes from single and ternary solutions using poly(acrylamide‐co‐N‐methylacrylamide) grafted katira gum hydrogel
Authors: Jana Subinoy , Ray Jagabandhu , Bhanja Sunil K. , Tripathy Tridib
Published: November 2017

A novel hydrogel poly(acrylamide‐co‐poly‐N‐methylacrylamide) grafted katira gum (KG) was synthesized via free radical copolymerization using a mixture of acrylamide and N‐methylacrylamide in presence of N,N′‐methylene‐bis‐acrylamide as a crosslinking agent. A series of hydrogels (KG‐1 to KG‐6) were prepared by varying amount of acrylamide and N‐methylacryamide. Poly‐acrylamide‐g‐katira gum (PAM‐g‐KG) and poly‐N‐methylacrylamide‐g‐katira gum (PNMA‐g‐KG) hydrogels were also prepared using same crosslinking agent. Swelling characteristics of all the prepared hydrogels in water were evaluated and the hydrogel with best swelling property (KG‐6) was identified. The hydrogel KG‐6 was characterized by FTIR, X‐ray diffractometer, and scanning electron microscopy and was used for the adsorption of textile dyes namely methylene blue (MB), malachite green (MG), and congo red (CR) from single and ternary solutions. Adsorption dynamics, kinetics, isotherm, and thermodynamics of all the prepared hydrogels were studied in the ternary dye solutions. The sorption kinetics data were fitted well to pseudo‐second order and the equilibrium adsorption data were found to follow Freundlich isotherm model. The thermodynamics studies showed that the adsorption process was spontaneous and exothermic in nature. The preferential dye adsorption by the hydrogel was followed in the order MB > MG > CR. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 45958.
What do the public know about anatomy? Anatomy education to the public and the implications
Authors: Taylor Adam M. , Diggle Peter , Wessels Quenton
Published: November 2017

Public knowledge of the anatomical “self” is lacking and evidence points towards a growing need for anatomy education to the wider public. The public were offered the opportunity to learn human anatomy and complete an anatomical knowledge survey afterwards. Sixty‐three participants volunteered to attempt to place 20 anatomical structures on a blank human body template. Responses were scored independently and then collated. A mixed effects logistic model was used to examine any associations with participants’ as a random effect and all other factors as fixed effects. Results showed a statistically significant quadratic trend with age. Participants in health‐related employment scored significantly higher than those not in health‐related employment. There was a significant interaction between gender and organ type with males scoring higher than females in identifying muscles, but not in identifying internal organs. The current study demonstrates the general public's eagerness to learn anatomy despite their limited knowledge of the human body, and the need for widening participation. Furthermore, it raises an awareness of the anatomical literacy needs of the general public, especially in school children and young adults. Furthermore, it emphasizes the value of health literacy as a focus in undergraduate medical education. Anatomy literacy appears to be neglected, and this experience provides an example of a possible mode of public engagement in anatomy. Anat Sci Educ 11: 117–123. © 2017 American Association of Anatomists.
Simultaneous determination and pharmacokinetic study of giraldoid a, giraldoid B in rat plasma after oral administration of Daphne giraldii Nitsche extracts by LC–MS/MS
Authors: Huyiligeqi  , Dong Xiaoxv , Fu Jing , Cao Sali , Yang Chunjing , You Longtai , Zhang Zhongyi , Ni Jian
Published: November 2017

A simple sensitive LC–MS/MS method has been developed for the simultaneous determination of giraldoid A and giraldoid B in rat plasma. The method was applied to pharmacokinetics studies of the two compounds from Daphne giraldii Nitsche. Chromatographic separation was accomplished on an Acquity UPLC™ BEH C18 column (100 × 2.1 mm, 1.7 mm) by gradient elution with a flow rate of 0.2 mL min−1. The method was linear over the concentration range of 1.0–1000 ng mL−1, and the lower limits of quantification were 1.04 ± 0.10 and 1.04 ± 0.09 ng mL−1, respectively. The intra‐ and inter‐day precisions (RSD) were <10.14 and 9.96%. The extraction recovery of the analytes was acceptable. Stability studies demonstrated that the two compounds were stable in the preparation and analytical process. The maximum plasma concentration was 687.78 ± 243.62 ng mL−1 for giraldoid A and 952.38 ± 131.99 ng mL−1 for giraldoid B. The time to reach the maximum plasma concentration was 0.50 ± 0.37 h for giraldoid A and 0.50 ± 0.66 h for giraldoid B. The validated method was successfully applied to investigate the concentration–time profiles of giraldoid A and giraldoid B.
Linking Environmental Management to Environmental Performance: The Interactive Role of Industry Context
Authors: Hartmann Julia , Vachon Stephan
Published: November 2017

In the past, corporate sustainability scholars advocated that, for many firms, environmental management could turn into a valuable capability conferring a competitive advantage. However, little attention has been paid to the role of the industry context and its influence on the relationship between environmental management and organizational performance. In this study, we examine the effect on this relationship of three contextual variables: munificence, dynamism and complexity. Drawing on longitudinal data from 336 firms representing 30 industries, we find that munificence enhances the degree to which a firm can leverage its environmental management capabilities to improve environmental performance. Copyright © 2017 John Wiley & Sons, Ltd and ERP Environment
Robust handling of clumping and stiffness in wet hair animation
Authors: Kim Jong‐Hyun , Kim Wook , Kim Young Bin , Im Jaeho , Lee Jung , Kim Sun‐Jeong
Published: November 2017

Simulating the clumping and stiffness of wet hair or fur is a challenging problem. The dynamics of wet hair or fur are characterized by clumping and stiffness at the tip, which can be seen clearly in running animals or headbanging scenes. Existing animation methods address these phenomena within preset scenarios. However, there is no consensus on a method for depicting the details of wet hair. This paper therefore proposes a new method for modeling the clumping and stiffness of wet hair or fur. Previous studies have focused on modeling the absorption of water into hair or fur, whereas this paper considers a realistic simulation of wet hair. Unlike dry hair strands, wet hair strands adjacent to one another are subject to a clumping force, gathering together and becoming more stiff as the saturation level of water increases. The proposed method builds on a surface‐tension model based on smoothed particle hydrodynamics to simulate the clumping force and to adjust the hair elasticity via stiffness constraints. The method gives realistic simulations of wet hair by maintaining the clumping force of the wet hair during movement and by simulating the stiffness of the hair in line with its water‐saturation level.
Nested PUF Proteins: Extending Target RNA Elements for Gene Regulation
Authors: Shinoda Kouki , Tsuji Shogo , Futaki Shiroh , Imanishi Miki
Published: November 2017

RNA‐binding proteins recognizing unique sequences within large transcriptomes serve as a powerful tool to control RNA metabolism. Pumilio and fem‐3 mRNA‐binding factor (PUF) proteins are considered good candidates for such tools, because they are typically composed of eight highly homologous repeat segments and can be designed to recognize arbitrary 8 nt RNA sequences. However, a specific 8 nt RNA sequence is found at multiple sites in various RNAs in the transcriptome, making it difficult to specifically target a single RNA. Designer PUF proteins recognizing longer RNA sequences should achieve more selective binding. Here, we propose an approach for creating 16‐repeat PUFs capable of targeting a single, unique mRNA in the transcriptome. Our design is simple and involves either the tandem alignment of two PUF segments or the nesting of one PUF segment within another. Designed 16‐repeat PUFs bound to the target RNA sequence without partial recognition derived from the original 8‐repeat PUF. Furthermore, based on our strategy, expression of an endogenous mRNA was selectively and effectively modulated, demonstrating the applicability of 16‐repeat PUF proteins for regulating endogenous RNA metabolism.
Laccase‐Mediated Grafting on Biopolymers and Synthetic Polymers: A Critical Review
Authors: Slagman Sjoerd , Zuilhof Han , Franssen Maurice C. R.
Published: November 2017

Laccase‐mediated grafting on lignocelluloses has gained considerable attention as an environmentally benign method to covalently modify wood, paper and cork. In recent decades this technique has also been employed to modify fibres with a polysaccharide backbone, such as cellulose or chitosan, to infer colouration, antimicrobial activity or antioxidant activity to the material. The scope of this approach has been further widened by researchers, who apply mediators or high redox potential laccases and those that modify synthetic polymers and proteins. In all cases, the methodology relies on one‐ or two‐electron oxidation of the surface functional groups or of the graftable molecule in solution. However, similar results can very often be achieved through simple deposition, even after extensive washing. This unintended adsorption of the active substance could have an adverse effect on the durability of the applied coating. Differentiating between actual covalent binding and adsorption is therefore essential, but proves to be challenging. This review not only covers excellent research on the topic of laccase‐mediated grafting over the last five to ten years, but also provides a critical comparison to highlight either the lack or presence of compelling evidence for covalent grafting.
Nonprecious‐metal Fe/N/C Catalysts Prepared from π‐Expanded Fe Salen Precursors toward an Efficient Oxygen Reduction Reaction
Authors: Tanaka Yuta , Onoda Akira , Okuoka Shin‐ichi , Kitano Tomoyuki , Matsumoto Koki , Sakata Takao , Yasuda Hidehiro , Hayashi Takashi
Published: November 2017

Non‐precious metal electrocatalysts are under investigation as alternatives to platinum‐group metal electrocatalysts for the oxygen reduction reaction (ORR), which is required for cathode materials in fuel cells. Herein, we describe a new method for the synthesis of metal and nitrogen‐containing carbon (M/N/C) catalysts with high ORR activity using π‐expanded Fe(Salen) precursors. The Fe/N/C ORR catalysts were obtained by pyrolysis of a mixture of carbon support (Vulcan XC‐72R) and the iron complex precursors. The Fe/N/C catalyst prepared from N,N'‐bis(2‐hydroxy‐1‐naphthylidene)‐1,2‐phenylenediamino‐iron(III) chloride has an onset potential of 860 mV, which is positively shifted by 60 mV from that of the catalyst prepared from the simple Fe(Salen) complex. The catalyst promotes efficient four‐electron reduction in the ORR. XAFS and XPS studies reveal that the Fe/N/C catalysts have atomically‐dispersed iron active sites and that the activity depends on the high content of pyridinic nitrogen. This new methodology facilitates the design of non‐precious metal‐carbon catalysts with excellent ORR activity.
Fluorescence Commutation and Surface Photopatterning with Porphyrin Tetradithienylethene Switches
Authors: Biellmann Thomas , Galanti Agostino , Boixel Julien , Wytko Jennifer A. , Guerchais Véronique , Samorì Paolo , Weiss Jean
Published: November 2017

Four tetradithienylethene (DTE) substituted porphyrins, the free base 1H2, and three metal derivatives (1Zn, 1Co, 1Ni), were synthesized and studied. These dyads, for which the DTE units are connected to the porphyrin's meso positions via a meta‐phenyl spacer, exhibit reversible photochromic properties in all cases, with conversion to the photostationary state (PSS) up to 88 %, as confirmed by absorption and NMR spectroscopies. Compounds 1H2 and 1Zn are fluorescent in solution and display a red emission. Upon irradiation with UV light to trigger the closing of the DTEs, the fluorescence of both the free base and zinc porphyrin was very efficiently quenched in solution. The reversible, photo‐switching of luminescence was retained in a tetra‐DTE free‐base porphyrin‐doped polystyrene film, for which photo‐patterning was demonstrated by confocal scanning microscopy. The tunable fluorescent properties of this multi‐DTE framework render this compound of interest as a photo‐rewritable fluorescent ink.
Ab Initio Ligand Field Molecular Mechanics and the Nature of Metal‐Ligand π‐Bonding in Fe(II) 2,6‐di(pyrazol‐1‐yl)pyridine Spin Crossover Complexes
Authors: Deeth Robert J. , Halcrow Malcolm A. , Kershaw Cook Laurence J. , Raithby Paul R.
Published: November 2017

A ligand field molecular mechanics (LFMM) force field has been constructed for the spin states of [Fe(bpp)2]2+ (bpp=2,6‐di(pyrazol‐1‐yl)pyridine) and related complexes. A new charge scheme is employed which interpolates between partial charges for neutral bpp and protonated [H3bpp]3+ to achieve a target metal charge. The LFMM angular overlap model (AOM) parameters are fitted to fully ab initio d orbital energies. However, several AOM parameter sets are possible. The ambiguity is resolved by calculating the Jahn–Teller distortion mode for high spin, which indicates that in [Fe(bpp)2]2+pyridine is a π‐acceptor and pyrazole a weak π‐donor. The alternative fit, assumed previously, where both ligands act as π‐donors leads to an inconsistent distortion. LFMM optimisations in the presence of [BF4]− or [PF6]− anions are in good agreement with experiment and the model also correctly predicts the spin state energetics for 3‐pyrazolyl substituents where the interactions are mainly steric. However, for 4‐pyridyl or 4‐pyrazolyl substituents, LFMM only treats the electrostatic contribution which, for the pyridyl substituents, generates a fair correlation with the spin crossover transition temperatures, T1/2, but in the reverse sense to the dominant electronic effect. Thus, LFMM generates its smallest spin state energy difference for the substituent with the highest T1/2. One parameter set for all substituted bpp ligands is insufficient and further LFMM development will be required.
Copper‐ or Thermally Induced Divergent Outcomes: Synthesis of 4‐Methyl 2H‐Chromenes and Spiro‐4H‐Pyrazoles
Authors: Zheng Yang , Qiu Lihua , Hong Kemiao , Dong Shanliang , Xu Xinfang
Published: November 2017

An unprecedented divergent outcome transformation of alkyne tethered N‐sulfonyl hydrazones is reported, which provides a direct and effective access to 4‐methyl 2H‐chromene derivatives and spiro‐4H‐pyrazoles in the presence of copper catalyst or under thermal conditions, respectively. The notable features of this process include readily available starting materials, an inexpensive copper catalyst, mild reaction conditions, broad substrate scope, diverse transformations and potential applications of these generated products. Mechanistic studies indicate that the 3H‐pyrazole, which is generated via direct [3+2] cycloaddition, is the communal key intermediate of these two divergent transformations. To the best of our knowledge, this is the only example of sulfonation reaction that goes through a cascade process involving 3H‐pyrazole, which was isolated and confirmed by single crystal X‐ray diffraction analysis for the first time.
Isomerisation of Liquid‐Crystalline Tristriazolotriazines
Authors: Rieth Thorsten , Röder Nico , Lehmann Matthias , Detert Heiner
Published: November 2017

Star‐shaped discotic liquid crystals with columnar superstructures constitute a highly interesting class of organic materials. Phenyl‐substituted tris[1,2,4]triazolo‐[1,3,5]triazine, prepared by a Huisgen reaction of phenyltetrazole and cyanuric chloride, represents an excellent core for discotic liquid crystals (DLCs). The thermal stability is not perfect, at temperatures above the clearing point, a successive threefold isomerization leads to a highly planar, C3‐symmetrical isomer, which mainly differs in the orientation of the aryl substituents to the centre of the molecule. A new class of discotic liquid crystals has been obtained: Equipped with peripheral alkoxy chains both isomers can form broad thermotropic mesophases. The optical, thermal, and physical properties were investigated by polarized optical microscopy, differential scanning calorimetry, wide‐angle X‐ray scattering, UV/Vis absorption and fluorescence spectroscopic measurements. The thermotropic properties are decisively affected by the molecular structure of the isomers, isomerisation leads to higher melting points but also the loss or even gain of mesomorphism is observed.
Absolute configuration of the diterpenoids icetexone and conacytone from Salvia ballotaeflora
Authors: Esquivel Baldomero , Burgueño‐Tapia Eleuterio , Bustos‐Brito Celia , Pérez‐Hernández Nury , Quijano Leovigildo , Joseph‐Nathan Pedro
Published: November 2017

Detailed literature inspections regarding the diterpenoids icetexone (1) and conacytone (3) reveal that the absolute configuration (AC) of these natural occurring compounds is not rigorously proven, despite they were originally isolated in 1976. This task is now completed by single‐crystal X‐ray diffraction Flack and Hooft parameters determination after processing data collected with Cu Kα graphite monochromated radiation. The AC of both compounds is further determined by vibrational circular dichroism measurements performed on icetexone acetate (2) and conacytone triacetate (4) since the solubility of 1 and 3 is limited. Comparison of the substituent chemical shifts (SCS) induced by acetylation of 1 and 3 to afford 2 and 4, respectively, reveals that in the case of icetexone, all six SCS values of the quinone ring are in excellent agreement with the expected values, while in the case of conacytone, three agree and three do not agree due to the presence of additional acetates near the quinone ring. Density functional theory calculations performed on 3‐hydroxythymoquinone (6) and its tautomer 4‐hydroxy‐1,2‐quinone 7, on 6‐hydroxythymoquinone (8) and its tautomer ortho‐quinone 9, and on icetexone (1) and the claimed natural occurring ortho‐quinone tautomer romulogarzone (5) indicate that 2‐hydroxy‐1,4‐quinones are more stable, by some 11‐14 kcal/mol, than their 4‐hydroxy‐1,2‐quinone tautomers, and therefore, romulogarzone (5) is inexistent.
Electronic and vibrational exciton coupling in oxidized trianglimines
Authors: Szymkowiak Joanna , Kwit Marcin
Published: November 2017

Readily available chiral trianglimine and their (poly)oxygenated congeners represent a unique class of macrocyclic rigid compounds optimal for testing electronic and vibrational circular dichroism exciton chirality methods. Electronic and vibrational circular dichroism spectra of such trianglimines are strongly affected by polar substituents in macrocycle skeletons. Double substitution by OH groups in each aromatic fragment of the macrocycle causes sign reversal of the exciton couplet in the region of the strongest UV absorption. On the other hand, electronic circular dichroism spectrum of the macrocycle having 2 methoxy groups shows 2 exciton couplets—the long‐wavelength positive and the second of the negative sign, observed at the shorter wavelengths.

VCD spectra of macrocyclic imines show vibrational exciton couplets in the region of strong C=N stretches. The signs of these couplets are positive and the opposite of the diamine chirality. For trianglimine macrocycles the interpretation of VCD spectra in terms of excitons is much more convincing than for electronic circular dichroism spectra.

By contrast,trans‐1,2‐diaminocyclohexane–based vicinal diimines, being a one‐third of the respective macrocycle, do not exhibit any vibrational exciton effect. Experimental data were confronted with DFT calculations. We observed good‐to‐excellent agreement between experimental and computed data.
Hemin and bile pigments are the secondary structure regulators of intrinsically disordered antimicrobial peptides
Authors: Zsila Ferenc , Juhász Tünde , Bősze Szilvia , Horváti Kata , Beke‐Somfai Tamás
Published: November 2017

The interaction of protoporphyrin compounds of human origin with the major bee venom component melittin (26 a.a., Z +6) and its hybrid derivative (CM15, 15 a.a., Z +6) were studied by a combination of various spectroscopic methods. Throughout a two‐state, concentration‐dependent process, hemin and its metabolites (biliverdin, bilirubin, bilirubin ditaurate) increase the parallel β‐sheet content of the natively unfolded melittin, suggesting the oligomerization of the peptide chains. In contrast, α‐helix promoting effect was observed with the also disordered but more cationic CM15. According to fluorescence quenching experiments, the sole Trp residue of melittin is the key player during the binding, in the vicinity of which the first pigment molecule is accommodated presumably making indole‐porphyrin π‐π stacking interaction. As circular dichroism titration data suggest, cooperative association of additional ligands subsequently occurs, resulting in multimeric complexes with an apparent dissociation constant ranged from 20 to 65 μM. Spectroscopic measurements conducted with the bilirubin catabolite urobilin and stercobilin refer to the requirement of intact dipyrrinone moieties for inducing secondary structure transformations. The binding topography of porphyrin rings on a model parallel β‐sheet motif was evaluated by absorption spectroscopy and computational modeling showing a slipped‐cofacial binding mode responsible for the red shift and hypochromism of the Soret band. Our results may aid to recognize porphyrin‐responsive binding motifs of biologically relevant, intrinsically disordered peptides and proteins, where transient conformations play a vital role in their functions.
The impacts of independent director and CEO duality on performance in the Chinese post‐institutional‐transition era
Authors: Lew Yong Kyu , Yu Jing , Park Jeong‐Yang
Published: November 2017

This paper investigates the influence of corporate governance on the performance of modern Chinese firms. Prior studies were inconclusive about the relationship between corporate governance and firm performance. Little research investigates the performance implications of board structure in the post‐institutional‐transition era in China. Based on agency and resource dependence theories, this paper examines the impacts of board composition and leadership structure on the performance of Chinese manufacturing firms that went public on the Shanghai and Shenzhen Stock Exchanges in 2010. The findings show that separating the posts of CEO and chair promotes better performance. However, appointing a larger proportion of outside independent directors to the board insignificantly affects performance. This research provides partial support for agency theory and extended insights into corporate governance in emerging economy firms. Copyright © 2017 ASAC. Published by John Wiley & Sons, Ltd.
A Molecular Hybrid for Mitochondria‐Targeted NO Photodelivery
Authors: Sodano Federica , Gazzano Elena , Fraix Aurore , Rolando Barbara , Lazzarato Loretta , Russo Marina , Blangetti Marco , Riganti Chiara , Fruttero Roberta , Gasco Alberto , Sortino Salvatore
Published: November 2017

The design, synthesis, spectroscopic and photochemical properties, and biological evaluation of a novel molecular hybrid that is able to deliver nitric oxide (NO) into mitochondria are reported. This molecular conjugate unites a tailored o‐CF3‐p‐nitroaniline chromophore, for photo‐regulated NO release, and a rhodamine moiety, for mitochondria targeting, in the same molecular skeleton via an alkyl spacer. A combination of steady‐state and time‐resolved spectroscopic and photochemical experiments demonstrate that the two chromogenic units preserve their individual photophysical and photochemical properties in the conjugate quite well. Irradiation with violet light triggers NO release from the nitroaniline moiety and photoionization in the rhodamine center, which also retains considerable fluorescence efficiency. The molecular hybrid preferentially accumulates in the mitochondria of A549 lung adenocarcinoma cells where it induces toxicity at a concentration of 1 μm, exclusively upon irradiation. Comparative experiments, carried out with ad‐hoc‐synthesized model compounds, suggest that the phototoxicity observed at such a low concentration is probably not due to NO itself, but rather to the formation of the highly reactive peroxynitrite that is generated from the reaction of NO with the superoxide anion.
Design, Synthesis, Biological Evaluation, and X‐ray Studies of HIV‐1 Protease Inhibitors with Modified P2′ Ligands of Darunavir
Authors: Ghosh Arun K. , Fyvie W. Sean , Brindisi Margherita , Steffey Melinda , Agniswamy Johnson , Wang Yuan‐Fang , Aoki Manabu , Amano Masayuki , Weber Irene T. , Mitsuya Hiroaki
Published: November 2017

The structure‐based design, synthesis, and biological evaluation of a series of nonpeptidic HIV‐1 protease inhibitors with rationally designed P2′ ligands are described. The inhibitors are designed to enhance backbone binding interactions, particularly at the S2′ subsite. Synthesis of inhibitors was carried out efficiently. The stereochemistry of alcohol functionalities of the P2′ ligands was set by asymmetric reduction of the corresponding ketone using (R,R)‐ or (S,S)‐Noyori catalysts. A number of inhibitors displayed very potent enzyme inhibitory and antiviral activity. Inhibitors 3g and 3h showed enzyme Ki values of 27.9 and 49.7 pm and antiviral activity of 6.2 and 3.9 nm, respectively. These inhibitors also remained quite potent against darunavir‐resistant HIV‐1 variants. An X‐ray structure of inhibitor 3g in complex with HIV‐1 protease revealed key interactions in the S2′ subsite.
Biobehavioral modulation of the exosome transcriptome in ovarian carcinoma
Authors: Lutgendorf Susan K. , Thaker Premal H. , Arevalo Jesusa M. , Goodheart Michael J. , Slavich George M. , Sood Anil K. , Cole Steve W.
Published: November 2017

BACKGROUND

Social factors in the patient macroenvironment have been shown to influence molecular events in the tumor microenvironment and thereby influence cancer progression. However, biomarkers providing a window into the longitudinal effects of biobehavioral factors on tumor biology over time are lacking. Exosome analysis is a novel strategy for in vivo monitoring of dynamic changes in tumor cells. This study examined exosomal profiles from patients with low or high levels of social support for epithelial‐mesenchymal transition (EMT) polarization and gene expression related to inflammation and β‐adrenergic signaling.

METHODS

Exosomes were isolated from plasma sampled from a series of 40 women before primary surgical resection of advanced‐stage, high‐grade ovarian carcinoma. Samples were selected for analysis on the basis of extremes of low and high levels of social support. After exosomal isolation and RNA extraction, a microarray analysis of the transcriptome was performed.

RESULTS

Primary analyses identified significant upregulation of 67 mesenchymal‐characteristic gene transcripts and downregulation of 63 epithelial‐characteristic transcripts in patients with low social support; this demonstrated increased EMT polarization (P = .0002). Secondary analyses using promoter sequence bioinformatics supported a priori hypotheses linking low social support to 1) increased activity of cyclic adenosine monophosphate response element binding protein (CREB)/activating transcription factor (ATF) family transcription factors that mediate the β‐adrenergic response to catecholamines via the cyclic adenosine monophosphate/protein kinase A signaling pathway (mean fold change for CREB: 2.24 ± 0.65; P = .0019; mean fold change for ATF: 2.00 ± 0.55; P = .0049) and 2) increased activity of the proinflammatory nuclear factor κB/Rel family of transcription factors (mean fold change: 2.10 ± 0.70; P = .0109).

CONCLUSIONS

These findings suggest the possibility of leveraging exosomes as a noninvasive assessment of biobehavioral factors to help to direct personalized treatment approaches. Cancer 2018;124:580‐6. © 2017 American Cancer Society.
Impact of the insurance type of head and neck cancer patients on their hospitalization utilization patterns
Authors: Gupta Avni , Sonis Stephen T. , Schneider Eric B. , Villa Alessandro
Published: November 2017

BACKGROUND

Head and neck cancer (HNC) patients with Medicaid, Medicare, or no insurance show poor outcomes in comparison with privately insured patients. It was hypothesized that nonprivate insurance coverage biases the selection of the treatment site to favor hospitals that are not associated with optimum treatment outcomes. This study assessed the relation between the insurance type of HNC patients and the hospital type for inpatient care.

METHODS

Adult HNC patients were identified from the Nationwide Inpatient Sample (2012 and 2013). The primary exposure was the insurance provider type. The outcome was the hospital type, which was classified by the hospital's ownership and its location and teaching status. Multivariate multinomial logistic regression models were constructed to control for the patient's age, sex, race, income, mortality risk, and geographic location. The analysis was weighted and was adjusted for multiple comparisons.

RESULTS

In all, 37,466 HNC patients representing 187,330 patients nationally were identified. After adjustments for age, sex, race, income, and mortality risk, in comparison with privately insured patients, Medicaid, Medicare, and uninsured patients demonstrated 1.14 to 2.29 increased odds of undergoing treatment at rural, urban nonteaching, private investor–owned, or government (nonfederal) hospitals (P < .05). This trend remained apparent even after adjustments for the geographic location.

CONCLUSIONS

Uninsured patients or patients insured by government programs predominantly underwent care for HNC at hospital types most often associated with inferior survival outcomes. This finding could explain some proportion of insurance‐related disparities in HNC outcomes. Further studies are warranted to determine whether interventions to promote equitable access to optimal hospital settings for patients, regardless of their insurance type, might improve outcomes among nonprivate insurance holders. Cancer 2018;124:760‐8. © 2017 American Cancer Society.
Estimating global treatment toxicity burden from adverse‐event data
Authors: Lee Shing M. , Hershman Dawn L. , Miao Jieling , Zhong Xiaobo , Unger Joseph M. , Cheung Ying Kuen Ken
Published: November 2017

BACKGROUND

A summary measure that reflects the global toxicity burden of a treatment is essential for comparing therapies. Current toxicity summaries are ad hoc and do not distinguish among the severities and types of toxicities. Here a clinically feasible method for estimating the toxicity burden, based on a prospective evaluation of the toxicity profile of a randomized clinical trial of 746 prostate cancer patients conducted by SWOG, is proposed.

METHODS

For 308 patients who experienced severe toxicities, 2 physicians randomly selected from 14 physicians evaluated each toxicity profile and assigned a visual analogue scale score (0‐10) based on their impression of the global burden of toxicities. With mixed‐effects models, severity scores and a 10‐point toxicity burden score (TBS) were derived from 27 predictors accounting for severe (grade 3) and life‐threatening (grade 4) toxicities for each organ class of the Common Terminology Criteria for Adverse Events.

RESULTS

For most organ classes, grade 3 toxicities had a TBS of 4.14 (95% confidence interval [CI], 3.65‐4.63), but infections, cardiovascular events, and pulmonary events had a higher TBS with differences of 0.87 (95% CI, 0.53‐1.21), 0.88 (95% CI, 0.51‐1.25), and 0.73 (95% CI, 0.22‐1.24), respectively. Moreover, most grade 4 events had a higher TBS than grade 3 events, except for hemorrhaging, pain, metabolic events, and musculoskeletal events. The intrarater and interrater correlations were 0.91 and 0.59, respectively.

CONCLUSIONS

The burden of toxicity grades differs with toxicity types. A TBS provides a toxicity burden summary that incorporates physicians' perspectives and differentiates between severe and life‐threatening toxicities and organ classes. Cancer 2018;124:858‐64. © 2017 American Cancer Society.
The Advantages of Using Fluorescent Proteins for In Vivo Imaging
Authors: Hoffman Robert M.
Published: November 2017

Fluorescent proteins have revolutionized biology by enabling what was formerly invisible to be seen clearly, and potentially enable imaging of all cells in living animals. There are numerous applications for in vivo imaging with fluorescent proteins, including use in cancer, immunology, infection, and neurobiology studies. This unit describes how introducing the GFP and RFP gene into malignant tissue has enabled imaging of primary cancer and the metastatic process with subcellular resolution in vivo. © 2017 by John Wiley & Sons, Inc.
Risk Assessment in the Research Laboratory
Authors: Burnett LouAnn C.
Published: November 2017

Risk assessment is a term that is applied to a process that we all use every day to make decisions. Conducting risk assessments while working in the laboratory should be integrated into the research culture. Reagents and equipment used in research laboratories can be hazardous if used improperly or without appropriate precautions. The first step in limiting risk is identifying the materials that can be hazardous. The second step is to assess the risk that they present during the experiments that will take place—a process called risk assessment. Once the hazards are identified and the risks assessed, a risk management strategy can be put in place to reduce the risks to an acceptable level. This process (hazard identification, risk assessment, risk management) must be repeated as often as new materials, new procedures, and new people are introduced into the laboratory. © 2017 by John Wiley & Sons, Inc.
Elucidating the Distribution and Speciation of Boron and Cesium in BCsX Zeolite Catalysts for Styrene Production
Authors: Martín Antonio J. , Mitchell Sharon , Scholder Olivier , Verel René , Hauert Roland , Bernard Laetitia , Jensen Christopher , Schwefer Meinhard , Pérez‐Ramírez Javier
Published: November 2017

An improved understanding of the nature and distribution of boron and cesium species in BCsX zeolites is a prerequisite to guide future developments in the environmentally attractive, yet challenging, production of styrene through the side‐chain alkylation of toluene with methanol. Herein, standard characterization and catalytic tests are complemented by integrated visualization through time‐of‐flight secondary‐ion mass spectrometry and energy‐dispersive X‐ray spectroscopy and detailed assessment by 133Cs and 11B NMR spectroscopy, to correlate the properties and performance during successive ion‐exchange and impregnation steps in the preparation of both powders and millimeter‐sized granules. The results highlight a significant impact of catalyst scaleup on the effective introduction of boron species, which originates chemical heterogeneity that is linked to selectivity losses. They also illustrate the complexity of elucidating the role of this promotor, which interacts with cesium cations and exhibits different coordination states and chemical environments, depending on the pretreatment.