bluuebunny/crossref_metadata_2025 huggingface dataset:
A Triphenylamine with Two Phenoxy Radicals Having Unusual Bonding Patterns and a Closed‐Shell Electronic State
Authors: Sakamaki Daisuke , Yano Soichiro , Kobashi Toshiyuki , Seki Shu , Kurahashi Takuya , Matsubara Seijiro , Ito Akihiro , Tanaka Kazuyoshi
Published: May 2015

Reported herein is the structure and the electronic properties of a novel triphenylamine derivative having two phenoxy radicals appended to the amino nitrogen atom. X‐ray single crystal analysis and the magnetic resonance measurements demonstrates the unexpected closed‐shell electronic structure, even at room temperature, of the molecule and two unusual CN bonds with multiple‐bond character. The theoretical calculations support the experimentally determined molecular geometry with the closed‐shell electronic structure, and predicted a small HOMO–LUMO gap originating from the nonbonding character of the HOMO. The optical and electrochemical measurements show that the molecule has a remarkably small HOMO–LUMO gap compared with its triphenylamine precursor.
Size‐Dependent Ligand Layer Dynamics in Semiconductor Nanocrystals Probed by Anisotropy Measurements
Authors: Hadar Ido , Abir Tsafrir , Halivni Shira , Faust Adam , Banin Uri
Published: May 2015

Colloidal semiconductor nanocrystals (NC) have reached a high level of synthetic control allowing the tuning of their properties, and their use in various applications. However, the surface of NCs and in particular their size‐dependent capping organic ligand behavior, which play an important role in the NC synthesis, dispersibility, and optoelectronic properties, is still not well understood. We study the size‐dependent properties of the ligand shell on the surface of NCs, by embedding surface bound dyes as a probe within the ligand shell. The reorientation times for these dyes show a linear dependence on the NC surface curvature indicating size‐dependent change in viscosity, which is related to a change in the density of the ligand layer because of the geometry of the surface, a unique feature of NCs. Understanding the properties of the ligand shell will allow rational design of the surface to achieve the desired properties, providing an additional important knob for tuning their functionality.
Attenuated Organomagnesium Activation of White Phosphorus
Authors: Arrowsmith Merle , Hill Michael S. , Johnson Andrew L. , Kociok‐Köhn Gabriele , Mahon Mary F.
Published: May 2015

Sequential reactions between a 2,6‐diisopropylphenyl‐substituted β‐diketiminato magnesium n‐butyl derivative and P4 allow the highly discriminating synthesis of unusual [nBu2P4]2− and [nBu2P8]2− cluster dianions.
Rapid Cationization of Gold Nanoparticles by Two‐Step Phase Transfer
Authors: Hassinen Jukka , Liljeström Ville , Kostiainen Mauri A. , Ras Robin H. A.
Published: May 2015

Cationic gold nanoparticles offer intriguing opportunities as drug carriers and building blocks for self‐assembled systems. Despite major progress on gold nanoparticle research in general, the synthesis of cationic gold particles larger than 5 nm remains a major challenge, although these species would give a significantly larger plasmonic response compared to smaller cationic gold nanoparticles. Herein we present the first reported synthesis of cationic gold nanoparticles with tunable sizes between 8–20 nm, prepared by a rapid two‐step phase‐transfer protocol starting from simple citrate‐capped particles. These cationic particles form ordered self‐assembled structures with negatively charged biological components through electrostatic interactions.
Construction of an Internally B3N3‐Doped Nanographene Molecule
Authors: Krieg Matthias , Reicherter Florian , Haiss Peter , Ströbele Markus , Eichele Klaus , Treanor Michael‐John , Schaub Renald , Bettinger Holger F.
Published: May 2015

The synthesis of a hexa‐peri‐hexabenzocoronene (HBC) with a central borazine core is described. The solid‐state structure of this BN‐doped HBC (BN‐HBC) is isotypic with that of the parent HBC. Scanning tunneling microscopy shows that BN‐HBC lies flat on Au(111) in a two‐dimensional pattern.
An Isolable Radical Anion of an Organosilicon Cluster Containing Only σ Bonds
Authors: Otsuka Kyohei , Matsumoto Naozumi , Ishida Shintaro , Kyushin Soichiro
Published: May 2015

The radical anion of octa‐tert‐butyloctasilacubane was generated and isolated. The EPR spectrum showed the satellites due to the tertiary 13C nuclei of the eight tert‐butyl groups. The X‐ray crystallographic analysis showed that the SiSi bonds are shortened and the SiC bonds are elongated compared with those of octa‐tert‐butyloctasilacubane. These results are well explained by the distribution of an unpaired electron in the singly occupied molecular orbital (SOMO).
A Catalyst Platform for Unique Cationic (Co)Polymerization in Aqueous Emulsion
Authors: Vasilenko Irina V. , Yeong Hui Yee , Delgado Marco , Ouardad Samira , Peruch Frédéric , Voit Brigitte , Ganachaud François , Kostjuk Sergei V.
Published: May 2015

Sodium dodecyl benzene sulfonate (DBSNa) surfactants, with a polydisperse and hyperbranched structure, combined with different rare earth metal salts generate highly water‐dispersible Lewis acid surfactant combined catalysts (LASCs). This platform of new complexes promotes fast, efficient cationic polymerization of industrially relevant monomers in direct emulsion at moderate temperature. The process described here does not require high shearing, long polymerization time, or large catalyst content. It allows the reproducible generation of high‐molar‐mass homopolymers of pMOS, styrene, and isoprene, as well as random or multiblock copolymers of the latter two, in a simple and straightforward one‐pot reaction.
Size of Gold Nanoparticles Driving Selective Amide Synthesis through Aerobic Condensation of Aldehydes and Amines
Authors: Miyamura Hiroyuki , Min Hyemin , Soulé Jean‐François , Kobayashi Shū
Published: May 2015

Metal nanoparticles (NPs) have attracted much attention in many fields due to their intrinsic characteristics. It is generally accepted that smaller NPs (1.5–3 nm) are more active than larger NPs, and reverse cases are very rare. We report here the direct aerobic oxidative amide synthesis from aldehydes and amines catalyzed by polymer‐incarcerated gold (Au) NPs. A unique correlation between imine/amide selectivity and size of NPs was discovered; Au‐NPs of medium size (4.5–11 nm) were found to be optimal. High yields were obtained with a broad range of substrates, including primary amines. Au‐NPs of medium size could be recovered and reused several times without loss of activity, and they showed good activity and selectivity in amide formation from alcohols and amines.
Iron Carbide Nanoparticles Encapsulated in Mesoporous Fe‐N‐Doped Carbon Nanofibers for Efficient Electrocatalysis
Authors: Wu Zhen‐Yu , Xu Xing‐Xing , Hu Bi‐Cheng , Liang Hai‐Wei , Lin Yue , Chen Li‐Feng , Yu Shu‐Hong
Published: May 2015

Exploring low‐cost and high‐performance nonprecious metal catalysts (NPMCs) for oxygen reduction reaction (ORR) in fuel cells and metal–air batteries is crucial for the commercialization of these energy conversion and storage devices. Here we report a novel NPMC consisting of Fe3C nanoparticles encapsulated in mesoporous Fe‐N‐doped carbon nanofibers, which is synthesized by a cost‐effective method using carbonaceous nanofibers, pyrrole, and FeCl3 as precursors. The electrocatalyst exhibits outstanding ORR activity (onset potential of −0.02 V and half‐wave potential of −0.140 V) closely comparable to the state‐of‐the‐art Pt/C catalyst in alkaline media, and good ORR activity in acidic media, which is among the highest reported activities of NPMCs.
Computer‐Aided Design of Ionic Liquids as CO2 Absorbents
Authors: Firaha Dzmitry S. , Hollóczki Oldamur , Kirchner Barbara
Published: May 2015

Ionic liquids (ILs), vary strongly in their interaction with CO2. We suggest simple theoretical approach to predict the CO2 absorption behavior of ILs. Strong interaction of the CO2 with the IL anions corresponds to chemical absorption whereas weak interaction indicates physical absorption. A predictive estimate with a clear distinction between physical and chemical absorption can be simply obtained according to geometries optimized in the presence of a solvation model instead of optimizing it only in gas phase as has been done to date. The resulting Gibbs free energies compare very well with experimental values and the energies were correlated with experimental capacities. Promising anions, for ionic liquids with reversible CO2 absorption properties can be defined by a reaction Gibbs free energy of absorption in the range of −30 to 16 kJ mol−1.
Frenkel‐Defect‐Mediated Chemical Ordering Transition in a Li–Mn–Ni Spinel Oxide
Authors: Ryoo Hyewon , Bae Hyung Bin , Kim Young‐Min , Kim Jin‐Gyu , Lee Seongsu , Chung Sung‐Yoon
Published: May 2015

Using spinel‐type Li(Mn1.5Ni0.5)O4 with two different cations, Mn and Ni, in the oxygen octahedra as a model system, we show that a cation ordering transition takes place through the formation of Frenkel‐type point defects. A series of experimental results based on atomic‐scale observations and in situ powder diffractions along with ab initio calculations consistently support such defect‐mediated transition behavior. In addition to providing a precise suggestion of the intermediate transient states and the resulting kinetic pathway during the transition between two phases, our findings emphasize the significant role of point defects in ordering transformation of complex oxides.
Epigenetic Genome Mining of an Endophytic Fungus Leads to the Pleiotropic Biosynthesis of Natural Products
Authors: Mao Xu‐Ming , Xu Wei , Li Dehai , Yin Wen‐Bing , Chooi Yit‐Heng , Li Yong‐Quan , Tang Yi , Hu Youcai
Published: May 2015

The small‐molecule biosynthetic potential of most filamentous fungi has remained largely unexplored and represents an attractive source for the discovery of new compounds. Genome sequencing of Calcarisporium arbuscula, a mushroom‐endophytic fungus, revealed 68 core genes that are involved in natural product biosynthesis. This is in sharp contrast to the predominant production of the ATPase inhibitors aurovertin B and D in the wild‐type fungus. Inactivation of a histone H3 deacetylase led to pleiotropic activation and overexpression of more than 75 % of the biosynthetic genes. Sampling of the overproduced compounds led to the isolation of ten compounds of which four contained new structures, including the cyclic peptides arbumycin and arbumelin, the diterpenoid arbuscullic acid A, and the meroterpenoid arbuscullic acid B. Such epigenetic modifications therefore provide a rapid and global approach to mine the chemical diversity of endophytic fungi.
The Donor‐Base‐Free Aggregation of Lithium Diisopropyl Amide in Hydrocarbons Revealed by a DOSY Method
Authors: Neufeld Roman , John Michael , Stalke Dietmar
Published: May 2015

Lithium diisopropyl amide (LDA) is a very prominent reagent that plays a key role in organic synthesis, serving as a base par excellence for a broad range of deprotonation reactions. However, the state of aggregation in solution in the absence of donor bases was unclear. In this paper we solved this problem by employing DOSY NMR experiments based on a newly elaborated external calibration curve (ECC) approach with normalized diffusion coefficients.
A Photoelectrochemical Solar Cell Consisting of a Cadmium Sulfide Photoanode and a Ruthenium–2,2′‐Bipyridine Redox Shuttle in a Non‐aqueous Electrolyte
Authors: Kageshima Yosuke , Kumagai Hiromu , Minegishi Tsutomu , Kubota Jun , Domen Kazunari
Published: May 2015

A photoelectrochemical (PEC) cell consisting of an n‐type CdS single‐crystal electrode and a Pt counter electrode with the ruthenium–2,2′‐bipyridine complex [Ru(bpy)3]2+/3+ as the redox shuttle in a non‐aqueous electrolyte was studied to obtain a higher open‐circuit voltage (VOC) than the onset voltage for water splitting. A VOC of 1.48 V and a short‐circuit current (ISC) of 3.88 mA cm−2 were obtained under irradiation by a 300 W Xe lamp with 420–800 nm visible light. This relatively high voltage was presumably due to the difference between the Fermi level of photo‐irradiated n‐type CdS and the redox potential of the Ru complex at the Pt electrode. The smooth redox reaction of the Ru complex with one‐electron transfer was thought to have contributed to the high VOC and ISC. The obtained VOC was more than the onset voltage of water electrolysis for hydrogen and oxygen generation, suggesting prospects for application in water electrolysis.
Catalytic Enantioselective Reaction of α‐Aminoacetonitriles Using Chiral Bis(imidazoline) Palladium Catalysts
Authors: Kondo Masaru , Nishi Tomoki , Hatanaka Tsubasa , Funahashi Yasuhiro , Nakamura Shuichi
Published: May 2015

The catalytic enantioselective reaction of diphenylmethylidene‐protected α‐aminoacetonitriles with imines has been developed. Good yields and diastereo‐ and enantioselectivities were observed for the reaction of various imines using chiral bis(imidazoline)/Pd catalysts. The reaction of α‐aminonitriles with di‐tert‐butyl azodicarboxylate afforded chiral α,α‐diaminonitriles in high yields with high enantioselectivities.
Ligandless C‐C bond formation via Suzuki–Miyaura reaction in micelles or water–ethanol solution using PdPtZn and PdZn nanoparticle thin films
Authors: Hoseini S. Jafar , Zarei Atiyeh , Rafatbakhsh Iran Hajar
Published: May 2015

PdPtZn and PdZn nanoparticle (NP) thin films were synthesized by the reduction of [PdCl2(cod)], [PtCl2(cod)] (cod = cis,cis‐1,5‐cyclooctadiene) and [Zn(acac)2] (acac = acetylacetonate) complexes at an oil–water interface. The structure and morphology of the as‐prepared NPs were characterized with X‐ray diffraction, transmission electron microscopy and energy dispersive analysis of X‐rays. Catalytic activity of the prepared NPs was investigated in the Suzuki–Miyaura cross‐coupling reaction in H2O–EtOH and various micellar media systems such as cetyltrimethylammonium bromide (cationic surfactant), sodium dodecylsulfate (anionic surfactant) and Pluronic P123 (non‐ionic surfactant). PdPtZn and PdZn thin films exhibited higher catalytic activity compared to Pd thin film in the Suzuki–Miyaura coupling reaction due to the appropriate interaction between palladium, platinum and zinc metals. Copyright © 2015 John Wiley & Sons, Ltd.
Thermal conductivity and electromagnetic shielding effectiveness of composites based on Ag‐plating carbon fiber and epoxy
Authors: Li Junpeng , Qi Shuhua , Zhang Mengyu , Wang Zhaofu
Published: May 2015

Thermally conductive and electromagnetic interference shielding composites comprising low content of Ag‐plating carbon fiber (APCF) were fabricated as electronic packing materials. APCF as conductive filler consisting of carbon fiber (CF) employed as the structural component to reinforce the mechanical strength, and Ag enhancing electrical conductivity, was prepared by advanced electroless Ag‐plating processing on CF surfaces. Ag coating had a thickness of 450 nm without oxide phase detected. The incorporation of 4.5 wt % APCF into epoxy (EP) substrate yielded thermal conductivity of 2.33 W/m·K, which is approximately 2.6 times higher than CF–EP composite at the same loading. The APCF–EP composite performed electromagnetic shielding effectiveness of 38–35 dB at frequency ranging from 8.2 to 12.4 GHz in the X band, and electromagnetic reflection was the dominant shielding mechanism. At loading content of APCF up to 7 wt %, thermal conductivity of APCF–EP composites increased to 2.49 W/m·K. Volume resistivity and surface resistivity decreased to 9.5 × 103 Ω·cm and 6.2 × 102 Ω, respectively, which approached a metal. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42306.
Joint effects of rotational extrusion and TiO2 on performance and antimicrobial properties of extruded polypropylene copolymer pipes
Authors: Li Xiao , Pi Lin , Nie Min , Wang Qi
Published: May 2015

In this study, effects of titanium dioxide (TiO2) and rotation extrusion on structures and properties of polypropylene random copolymer (PPR) pipes were investigated. The experimental results showed that with the presence of TiO2, not only the antibacterial ability of PPR pipe was improved significantly but also the toughness was enhanced since a large number of PP chains were promoted to crystallize into β‐form crystals. Furthermore, when rotation extrusion was introduced into the process of PPR pipe, the drag hoop flow caused by mandrel and die rotation was superposed on the axial flow, so the polymer melts in the annulus underwent a helical flow and its flow direction deviated from the axis to drive the molecular orientation off the axial direction, bringing out the increased hoop strength. As a result, PPR pipe with excellent performance was prepared under the combined effect of rotation extrusion and TiO2. The antibacterial activity was 99.2%, the hoop tensile strength reached 27.5 MPa, 67.7% higher than that of the convention‐extruded PPR pipe with TiO2, and the impact strength was 10.9 kJ/m2, increased by 81.6% compared to that of the rotation‐extruded pure PPR pipe. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42410.
Friction and wear behavior of styrene butadiene rubber‐based composites reinforced with microwave‐devulcanized ground tire rubber
Authors: Karabork Fazliye , Akdemir Ahmet
Published: May 2015

In this work, the tribological properties of a new material obtained by revulcanization with styrene butadiene rubber (SBR) and devulcanized ground tire rubber (GTR) were investigated. GTR was devulcanized using the microwave method at a constant power while varying the microwave exposure time. Devulcanized rubber (DV‐R) and untreated GTR were revulcanized by mixing with SBR at different rates (10, 30, 50 phr). To determine friction and wear characteristics of the samples, pin (ball) on disc and abrasion tests were conducted. Scanning electron microscopy (SEM) was employed to observe the worn surfaces of the composites to correlate the experimental test results to the wear mechanisms. All of these tests and experiments were performed on original vulcanized rubber samples for comparison. The composites exhibited different friction and wear behavior due to morphology, dispersion behavior and devulcanization functionalization of ground tire rubber. In general, DV‐R/SBR composites exhibited improvement in both mechanical and tribological properties. However, the enhanced compatibility of DV‐R resulting from the specific chemical coupling of DV‐R with SBR was crucial for the mechanical, friction and wear properties. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42419.
Polythiophene based fluorescent probe for copper ions with high sensitivity
Authors: Guo Chaoxia , Jiang Shouxiang , Zhu Wenxue , Yang Xiuxia , Pei Meishan , Zhang Guangyou
Published: May 2015

Two new conjugated polymers poly{3‐({4‐[(2‐hydrazino‐2‐oxoethyl)(methyl)amino]cyclohexylidene}methyl)thiophene}(P1) and poly{3‐({4‐[(3‐hydrazino‐3‐oxopropyl)(methyl)amino]cyclohexylidene}methyl)thiophene}(P2) were synthesized, and their optical properties were investigated. P1 exhibited excellent selectivity toward Cu2+ ions in 50% water solution, the fluorescence color of P1 changed distinctly from greenyellow to colorless in the presence of Cu2+ under UV‐light, while introduction of other metal ions could not induce such significant variation. Moreover, highly sensitive detection of Cu2+ ions was demonstrated in 90% water solution. Its high metal‐chelating capability allowed Cu2+ recognition with a detection limit of 3.2 × 10−10 M. These results indicated that this kind of nonionic polymer containing multidentate ligand could be used as a highly selective and sensitive chemosensor for Cu2+ detection. The proposed binding mode of P1 with Cu2+ was supported by DFT calculation using Gaussian 03. Unlike P1, P2 showed no obvious fluorescent change in the presence of various metal ions due to its space steric hindrance resulted from N/O distribution on the side chain of P2. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42440.
Improving the hydrophobicity of nylon fabric by consecutive treatment with poly(acrylic acid), tetraethylorthosilicate, and octadecylamine
Authors: Du Jinmei , Luo Xiongfang , Fu Zhen , Xu Changhai , Ren Xuehong , Gao Weidong , Li Yong
Published: May 2015

Nylon fabric was consecutively treated with poly(acrylic acid) (PAA), tetraethylorthosilicate (TEOS), and octadecylamine (OA) to improve its hydrophobicity. We proposed that PAA could be used as a mediator between nylon and OA to provide a high density of the carboxyl moiety. TEOS was used to increase the surface roughness of the nylon fabric by hydrolysis and condensation, and OA was used to reduce the surface energy of the nylon fabric with its long alkyl chains. Both the increase in the surface roughness and the reduction in the surface energy contributed to the improvement of the hydrophobicity of the nylon fabric. The hydrophobicity of the treated nylon fabric was evaluated by the measurement of the water contact angle, water resistance to spray, and hydrostatic pressure. Scanning electron microscopy images showed that the surface roughness of the nylon fabric was significantly increased by treatment with TEOS. The nylon fabric with the PAA/TEOS/OA consecutive treatment exhibited a water contact angle of 125°, a resistance to water spray of 90, and a hydrostatic pressure of 275 mm. It was interesting to find that the PAA/TEOS/OA consecutive treatment slightly enhanced the wrinkle recovery but had no apparent effects on the degree of whiteness and the breaking strength of the nylon fabric. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci.2015,132, 42456.
Thermal conductivity of polyimide/boron nitride nanocomposite films
Authors: Diaham Sombel , Saysouk François , Locatelli Marie‐Laure , Belkerk Boubakeur , Scudeller Yves , Chiriac Rodica , Toche François , Salles Vincent
Published: May 2015

The thermal conductivity of polyimide/boron nitride (PI/BN) nanocomposite thin films has been studied for two sizes of BN nanofillers (40 and 120 nm) and for a wide range of content. A strong influence of BN particle size on the thermal conduction of PI has been identified. In the case of the largest nanoparticles (hexagonal‐BN), the thermal conductivity of PI/h‐BN (120 nm) increases from 0.21 W/mK (neat PI) up to 0.56 W/mK for 29.2 vol %. For the smaller nanoparticles (wurtzite‐BN), PI/w‐BN (40 nm), we observed two different behaviors. First, we see a decrease until 0.12 W/mK for 20 vol % before increasing for higher filler content. The initial phenomenon can be explained by the Kapitza theory describing the presence of an interfacial thermal resistance barrier between the nanoparticles and the polymer matrix. This is induced by the reduction in size of the nanoparticles. Modeling of the experimental results allowed us to determine the Kapitza radius aK for both PI/h‐BN and PI/w‐BN nanocomposites. Values of aK of 7 nm and >500 nm have been obtained for PI/h‐BN and PI/w‐BN nanocomposite films, respectively. The value obtained matches the Kapitza theory, particularly for PI/w‐BN, for which the thermal conductivity is expected to decrease compared to that of neat PI. The present work shows that it seems difficult to enhance the thermal conductivity of PI films with BN nanoparticles with a diameter <100 nm due to the presence of high interfacial thermal resistance at the BN/PI interfaces. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42461.
Numerical simulation on residual thickness of pipes with curved sections in water‐assisted co‐injection molding
Authors: Kuang Tang‐Qing , Xu Bai‐Ping , Zhou Guo‐Fa , Turng Lih‐Sheng
Published: May 2015

The residual thicknesses of the skin and the inner layers are important quality indicators of water‐assisted co‐injection molding (WACIM) process or overflow WACIM (O‐WACIM) parts. At the curved section, the residual thicknesses change significantly. A numerical simulation program based on the computational fluid dynamics method was developed to simulate the O‐WACIM process. After the numerical simulation program was validated with the experimental results, it was used to study the effects of the bending radii and bending angles on the residual thicknesses of the skin and inner layers of O‐WACIM parts. The results showed that the penetration of the inner melt and water was always close to the inner concave side due to the higher local pressure gradient and temperature. The effects of processing parameters on the residual thicknesses of the skin and inner layers were investigated using the orthogonal simulation method. It was found that the residual thicknesses of the skin/inner layer at the inner concave/outer convex side are mainly influenced by different parameters. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42468.
Structure–property relationship of polyimide fibers containing ether groups
Authors: Chang Jingjing , Niu Hongqing , He Min , Sun Meng , Wu Dezhen
Published: May 2015

The copolyimide (co‐PI) fibers with outstanding mechanical properties were prepared by a two‐step wet‐spinning method, derived from the design of combining 4,4′‐oxydianiline (ODA) with the rigid 3,3′,4,4′‐biphenyltetracarboxylic dianhydride (BPDA)/p‐phenylenediamine (p‐PDA) backbone. The mechanical properties of PI fibers were drastically improved with the optimum tensile strength of 2.53 GPa at a p‐PDA/ODA molar ratio of 5/5, which was approximately 3.7 times the tensile strength of BPDA/p‐PDA PI fibers. Two‐dimensional wide‐angle X‐ray diffraction indicated that the highly oriented structures were formed in the fibers. Two‐dimensional small‐angle X‐ray scattering revealed the existence of the needle‐shaped microvoids aligned parallel to the fiber axis, and the introduction of ODA led to the reduction in the size of the microvoids. As a result, the significantly improved mechanical properties of PI fibers were mainly attributed to the gradually formed homogeneous structures. The co‐PI fibers also exhibited excellent thermal stabilities of up to 563°C in nitrogen and 536°C in air for a 5% weight loss and glass transition temperatures above 279°C. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42474.
Clinical Phenotype Classifications Based on Static Varus Alignment and Varus Thrust in Japanese Patients With Medial Knee Osteoarthritis
Authors: Iijima Hirotaka , Fukutani Naoto , Aoyama Tomoki , Fukumoto Takahiko , Uritani Daisuke , Kaneda Eishi , Ota Kazuo , Kuroki Hiroshi , Matsuda Shuichi
Published: May 2015

Objective

To investigate the association between knee pain during gait and 4 clinical phenotypes based on static varus alignment and varus thrust in patients with medial knee osteoarthritis (OA).

Methods

Patients in an orthopedic clinic (n = 266) diagnosed as having knee OA (Kellgren/Lawrence [K/L] grade ≥1) were divided into 4 phenotype groups according to the presence or absence of static varus alignment and varus thrust (dynamic varus): no varus (n = 173), dynamic varus (n = 17), static varus (n = 50), and static varus + dynamic varus (n = 26). The knee range of motion, spatiotemporal gait parameters, visual analog scale scores for knee pain, and scores on the Japanese Knee Osteoarthritis Measure were used to assess clinical outcomes. Multiple logistic regression analyses identified the relationship between knee pain during gait and the 4 phenotypes, adjusted for possible risk factors, including age, sex, body mass index, K/L grade, and gait velocity.

Results

Multiple logistic regression analysis showed that varus thrust without varus alignment was associated with knee pain during gait (odds ratio [OR] 3.30, 95% confidence interval [95% CI] 1.08–12.4), and that varus thrust combined with varus alignment was strongly associated with knee pain during gait (OR 17.1, 95% CI 3.19–320.0). Sensitivity analyses applying alternative cutoff values for defining static varus alignment showed comparable results.

Conclusion

Varus thrust with or without static varus alignment was associated with the occurrence of knee pain during gait. Tailored interventions based on individual malalignment phenotypes may improve clinical outcomes in patients with knee OA.
Brief Report: Clinical Course Over Two Years in Patients With Early Nonradiographic Axial Spondyloarthritis and Patients With Ankylosing Spondylitis Not Treated With Tumor Necrosis Factor Blockers: Results From the German Spondyloarthritis Inception Cohort
Authors: Poddubnyy Denis , Haibel Hildrun , Braun Jürgen , Rudwaleit Martin , Sieper Joachim
Published: May 2015

Objective

To investigate the clinical course of disease over 2 years in patients with nonradiographic axial spondylarthritis (SpA) and patients with ankylosing spondylitis (AS).

Methods

The study group comprised 303 patients with axial SpA (158 patients with AS and a symptom duration of ≤10 years and 145 patients with nonradiographic axial SpA and a symptom duration of ≤5 years) who did not receive tumor necrosis factor (TNF) blockers during 2 years of followup.

Results

The Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) did not differ between patients with nonradiographic axial SpA and those with AS at any time point during followup. The Bath Ankylosing Spondylitis Functional Index was significantly higher in patients with AS at baseline only, but spinal mobility was generally better in patients with nonradiographic SpA compared with those with AS. At all time points, C‐reactive protein (CRP) levels were significantly higher in patients with AS compared with patients with nonradiographic axial SpA. Accordingly, the Ankylosing Spondylitis Disease Activity Score (ASDAS) was significantly higher in the patients with AS at 2 of 4 time points. When patients with a BASDAI score of ≥4 plus an elevated CRP level at baseline were analyzed over time, there were no significant differences in the proportions of patients with nonradiographic axial SpA and those with AS who reached low disease activity status at ≥2 time points during 2 years of followup when a clinical definition of low disease activity was used (38% and 35%, respectively, achieved a BASDAI score of <4, and 13% and 15%, respectively, achieved a score of ≤2). When definitions that included the CRP level were used, however, a greater percentage of patients with nonradiographic axial SpA achieved low disease activity (25% of patients with nonradiographic axial SpA and 10% of patients with AS achieved a BASDAI score of <4 and a normal CRP level, and 13% of patients with nonradiographic axial SpA and 3% of those with AS achieved ASDAS‐defined low disease activity).

Conclusion

Patients with nonradiographic axial SpA and those with AS who were not treated with TNF blockers demonstrated a similar clinical disease course over 2 years. Patients with nonradiographic axial SpA achieved a status of low disease activity more frequently than those with AS if outcome parameters that included the CRP level were used.
Performance of an Eco‐Driving Model Predictive Control System for HEVs during Car Following
Authors: Yu Kaijiang , Liang Qing , Hu Zhiguo , Yang Junqi , Zhang Hongwei
Published: May 2015

This paper presents a model predictive control approach for the energy management problem of hybrid electric vehicles (HEVs) with variable time headway during car following. The new features of this study are as follows. First, a new method using model predictive control with fixed time headway is proposed to improve fuel economy outside the HEV. Second, the battery state of charge profile is scheduled systematically to improve fuel economy inside the HEV compared with the vehicle spacing influence outside the HEV. Computer simulation results are shown using the approaches with variable time headway and fixed time headway. The conclusion is that the model predictive control approach is effective for the energy management problem of the HEV system during car following.
Event‐Triggered Control for Multi‐Agent Systems with General Directed Topology and Time Delays
Authors: Gao Lan , Liao Xiaofeng , Li Huaqing , Chen Guo
Published: May 2015

Recent years have witnessed a growing interest in event‐triggered strategies for coordination and cooperative control of multi‐agent systems. However, the most previous works and developments focus on the interactive network that has no communication delays. This paper deals with the consensus problem of an agent system with event‐triggered control strategy under communication time delays. We first propose a time delays system model, then present a novel event triggering function that not only avoids continuous communication but also excludes the Zeno behavior. Furthermore, we provide the consensus analysis using an inequality technique instead of the traditional linear matrix inequality method, and we demonstrate that the inter‐event times for each agent are strictly positive, which implies that the Zeno behavior can be excluded. Finally, simulation results show the effectiveness of the proposed approach and illustrate the correctness of the theoretical results.
Zn‐doped CaTiO3:Eu3+ red phosphors for enhanced photoluminescence in white LEDs by solid‐state reaction
Authors: Wu Yibing , Zhao Fengyang , Piao Xianqing , Ruan Kaibin
Published: May 2015

Zn‐doped CaTiO3:Eu3+ red phosphors for enhanced photoluminescence in white light‐emitting diodes (LEDs) were synthesized by a solid‐state method. The structure and morphology of the obtained phosphor samples were observed by X‐ray diffraction (XRD) and scanning electron microscopy (SEM), and the impact of Ca, Zn and Eu content on their photoluminescence properties was studied. The results indicated that Zn not only participates in the formation of defects in suitable lattice matrices but also has a role in flux in the transformation from ZnO to Zn2TiO4, which is beneficial for the enhancement of photoluminescence properties. Photoluminescence test data showed that the Zn‐doped phosphor is excited efficiently by near‐ultraviolet (NUV) light at wavelengths around 398 nm and emits an intense red light with a broad peak around 616 nm corresponding to the 5D0→7F2 transition of Eu3+. The intensity of this phosphor emission is three times stronger than that without Zn‐doping. Furthermore, this phosphor has very good thermal stability, high color purity and a low sintered temperature, all of which suggest its potential as a promising red phosphor for white LEDs. Copyright © 2015 John Wiley & Sons, Ltd.
Thermoluminescence properties of gamma‐irradiated nano‐structure hydroxyapatite
Authors: Shafaei M. , Ziaie F. , Sardari D. , Larijani M. M.
Published: May 2015

The suitability of nano‐structured hydroxyapatite (HAP) for use as a thermoluminescence dosimeter was investigated. HAP samples were synthesized using a hydrolysis method. The formation of nanoparticles was confirmed by X‐ray diffraction and average particle size was estimated to be ~30 nm. The glow curve exhibited a peak centered at around 200 °C. The additive dose method was applied and this showed that the thermoluminescence (TL) glow curves follow first‐order kinetics due to the non‐shifting nature of Tm after different doses. The numbers of overlapping peaks and related kinetic parameters were identified from Tm–Tstop through computerized glow curve deconvolution methods. The dependence of the TL responses on radiation dose was studied and a linear dose response up to 1000 Gy was observed for the samples. Copyright © 2015 John Wiley & Sons, Ltd.
DNA cyclization and looping in the wormlike limit: Normal modes and the validity of the harmonic approximation
Authors: Giovan Stefan M. , Hanke Andreas , Levene Stephen D.
Published: May 2015

For much of the last three decades, Monte Carlo‐simulation methods have been the standard approach for accurately calculating the cyclization probability, J, or J factor, for DNA models having sequence‐dependent bends or inhomogeneous bending flexibility. Within the last 10 years approaches based on harmonic analysis of semi‐flexible polymer models have been introduced, which offer much greater computational efficiency than Monte Carlo techniques. These methods consider the ensemble of molecular conformations in terms of harmonic fluctuations about a well‐defined elastic‐energy minimum. However, the harmonic approximation is only applicable for small systems, because the accessible conformation space of larger systems is increasingly dominated by anharmonic contributions. In the case of computed values of the J factor, deviations of the harmonic approximation from the exact value of J as a function of DNA length have not been characterized. Using a recent, numerically exact method that accounts for both anharmonic and harmonic contributions to J for wormlike chains of arbitrary size, we report here the apparent error that results from neglecting anharmonic behavior. For wormlike chains having contour lengths less than four times the persistence length, the error in J arising from the harmonic approximation is generally small, amounting to free energies less than the thermal energy, kBT. For larger systems, however, the deviations between harmonic and exact J values increase approximately linearly with size. © 2015 Wiley Periodicals, Inc. Biopolymers : 527–537, 2015.
Folding stability modulation of the villin headpiece helical subdomain by 4‐fluorophenylalanine and 4‐methylphenylalanine
Authors: Hsu Wei‐Lin , Shih Ting‐Chia , Horng Jia‐Cherng
Published: May 2015

HP36, the helical subdomain of villin headpiece, contains a hydrophobic core composed of three phenylalanine residues (Phe47, Phe51, and Phe58). Hydrophobic effects and electrostatic interactions were shown to be the critical factors in stabilizing this core and the global structure. To assess the interactions among Phe47, Phe51, and Phe58 residues and investigate how they affect the folding stability, we implanted 4‐fluorophenylalanine (Z) and 4‐methylphenylalanine (X) into the hydrophobic core of HP36. We chemically synthesized HP36 and its seven variants including four single mutants whose Phe51 or Phe58 was replaced with Z or X, and three double mutants whose Phe51 and Phe58 were both substituted. Circular dichroism and nuclear magnetic resonance measurements show that the variants exhibit a native HP36 like fold, of which F51Z and three double mutants are more stable than the wild type. Molecular modeling provided detailed interaction energy within the phenylalanine residues, revealing that electrostatic interactions dominate the stability modulation upon the introduction of 4‐fluorophenylalanine and 4‐methylphenylalanine. Our results show that these two non‐natural amino acids can successfully tune the interactions in a relatively compact hydrophobic core and the folding stability without inducing dramatic steric effects. Such an approach may be applied to other folded motifs or proteins. © 2015 Wiley Periodicals, Inc. Biopolymers 103: 627–637, 2015.
Biogenesis, characterization, and the effect of vicenin‐gold nanoparticles on glucose utilization in 3T3‐L1 adipocytes: A bioinformatic approach to illuminate its interaction with PTP 1B and AMPK
Authors: Chockalingam Shivashri , Thada Rajarajeshwari , Dhandapani Ramesh Kumar , Panchamoorthy Rajasekar
Published: May 2015

This study reported the synthesis of Vicenin‐2 gold nanoparticles (VN‐AuNPs) and evaluated their effect on the glucose utilization efficiency of 3T3‐L1 adipocytes. The VN‐AuNPs were characterized by microscopic, DLS and spectral analysis. The bio‐reducing efficiency of Vicenin‐2 (VN) was computed and confirmed by HPLC analysis. The stability of VN‐AuNPs in various physiological media was explored. The cytotoxicity and glucose uptake assays were performed in 3T3‐L1 adipocytes. The docking of VN with PTP1B and AMPK was also performed. The color change and UV absorption at 537 nm preliminarily confirmed the VN reduced gold nanoparticles. The VN‐AuNPs appeared as spherical particles (57 nm) and face centered cubic crystals under TEM and XRD analysis, respectively. Its zeta potential was found to be −6.53 mV. The FT‐IR spectra of VN and its AuNPs confirmed its stability. The computed reducing potential of VN was similar to the extent of VN utilized during the synthesis of VN‐AuNPs. The VN‐AuNPs showed a remarkable stability in different physiological media. At 100 µM concentration, VN‐AuNPs displayed 78.21% cell viability. A concentration dependent increase in glucose uptake was noted in 3T3‐L1 adipocytes when incubated with VN‐AuNPs. The docking data revealed a strong interaction of VN with the binding pockets of PTP1B and AMPK. This demonstrates that the fabricated VN‐AuNPs might enhance the intracellular VN availability mediated cellular glucose utilization and this would serve as a novel nanodrug for the management of diabetes. © 2015 American Institute of Chemical Engineers Biotechnol. Prog., 31:1096–1106, 2015
Transcatheter, inflatable, and fully repositionable aortic valve: Preliminary results using a modified implantation technique
Authors: Kische Stephan , D'Ancona Giuseppe , Agma Hüseyin U. , Gürer Hakan , Ortak Jasmin , Elsässer Albrecht , Öner Alper , Ince Hüseyin
Published: May 2015

Objectives

We present our experience with an inflatable, non‐metallic, fully retrievable, and repositionable transcatheter aortic valve [Direct Flow® Medical (DFM)] focusing on technical features adopted during implantation.

Background

Implantation techniques of new generation percutaneous aortic valves are still developing and with experience implementations are described.

Methods

The “low pressure” (initial valve inflation at 4 ATM, lower than the recommended 12 ATM) and the “alternate aortic curve” techniques (initial valve pulling either from the wire running on the side of the inner or from the one on the outer aortic curve) are part of our modified protocol for DFM® implantation.

Results

Forty‐two consecutive patients underwent TAVI with DFM. The “low pressure” technique was used in all patients. In 27 (64.3%) patients the bulkiest calcifications were on the inner aortic curve side, and an inner curve technique was used to initiate valve pulling toward the annular hinge point. In the remaining 15 (35.7%) patients, an outer curve technique was used. Neither pull‐through nor re‐valving was reported. Valve performance showed mean gradient of 8.9 mm Hg. Mild paravalvular leak was reported in seven (16%) patients. No one experienced moderate or severe aortic insufficiency. Thirty‐day mortality was 9.5% (4/42).

Conclusion

The “low pressure technique” and the “alternate curve technique” guarantee an anatomy and patient tailored approach to achieve controlled and finely tuned valve seating. © 2015 Wiley Periodicals, Inc.
Being reasonable during coronary revascularization
Authors: Belardi Jorge A. , Albertal Mariano
Published: May 2015

Key Points

The SYNTAX score is an angiographically based tool useful for clinical decision‐making prior to coronary revascularization.

The residual SYNTAX score (after angioplasty) is an independent predictor of clinical long‐term outcome in patients with complex coronary artery disease.

Both scores require functional lesion assessment.

Adding clinical risk factors to both scores enhances their performance.
Eliminate the sheath and maximize the working space: Sheathless transradial guiding catheters
Authors: Gilchrist Ian C.
Published: May 2015

Key Points

Use of a sheathless 6.5‐F guide may provide an option for transradial access in patients with smaller radial arteries or in need of a larger diameter guide.

This sheathless system avoids many of the problems inherent in home‐made systems as it is hydrophilic coated and has a tight interface between components reducing vascular trauma on insertion.

Advantages of this system need to be weighed against its relative thermal instability for support, while its low‐resistance from hydrophilic coatings gives a different.
Correlation between Structural and Catalytic Properties of Copper Supported on Porous Alumina for the Ethanol Dehydrogenation Reaction
Authors: Cassinelli Wellington H. , Martins Leandro , Passos Aline R. , Pulcinelli Sandra H. , Rochet Amélie , Briois Valérie , Santilli Celso V.
Published: May 2015

Structural and surface features of highly dispersed copper catalysts supported on hierarchical porous alumina were evaluated for the ethanol dehydrogenation reaction. The catalysts were prepared by incipient wetness impregnation of alumina obtained by a dual template sol–gel procedure. Structural characterizations provided evidence that the copper was highly dispersed on the alumina in the form of monomeric octahedral Cu2+ species adsorbed into an incomplete layer. A two‐step reduction was observed for the catalysts in a temperature range of 50–250 °C under H2/He flow. The temperature for onset of reduction and the percentage of Cu+ species formed upon activation were dependent on the Cu loading. At lower Cu loadings, the amount of Cu+ increased, leading to a slower and less complete reduction. Based on the apparent activation energy and turnover frequency, it could be concluded that Cu+ containing a mixture of Cu+/Cu0 results in a more efficient catalyst than Cu0 for the ethanol dehydrogenation reaction.
High‐Throughput Synthesis of Uniform Silver Seed Particles by a Continuous Microfluidic Synthesis Platform
Authors: Thiele Matthias , Knauer Andrea , Csáki Andrea , Mallsch Daniell , Henkel Thomas , Köhler Johann Michael , Fritzsche Wolfgang
Published: May 2015

Controlled silver particle geometries require at least a synthesis in two steps which strongly differ in their reaction kinetics. For the first step, the very fast seed formation, chaotic advection‐based micromixers are tested in combination with a batch reactor for the growth step. Nanoparticles with narrow size distribution and excellent shape uniformity can be prepared in large batches. To achieve a highly reproducible and homogeneous particle solution, a microfluidic system containing three different micromixers for optimal mixing of the chemical precursors is established, allowing stringent control of every synthesis step. The produced silver particles can be used as seeds for forming anisotropic particles. Their further potential is demonstrated by preparation of anisotropic silver triangles. The thus generated seed particles are better suited for growing to triangles than those from conventional batch synthesis.
Probing Ionic Crystals by the Invariom Approach: An Electron Density Study of Guanidinium Chloride and Carbonate
Authors: Nelyubina Yulia V. , Lyssenko Konstantin A.
Published: May 2015

A comparative study of two guanidinium salts, chloride and carbonate, is carried out to test the performance of the invariom approach for ionic crystals. Although treating them as formed by isolated ions with no charge transfer between them, the invariom approach provides features of interionic contacts that are amazingly similar to those obtained from conventional charge density analysis of high‐resolution X‐ray diffraction data, thus emerging as an easy way towards reliable description of chemical bonding peculiarities in ionic crystals.
Highly Functionalized Cyclopentane Derivatives by Tandem Michael Addition/Radical Cyclization/Oxygenation Reactions
Authors: Holan Martin , Pohl Radek , Císařová Ivana , Klepetářová Blanka , Jones Peter G. , Jahn Ullrich
Published: May 2015

Densely functionalized cyclopentane derivatives with up to four consecutive stereocenters are assembled by a tandem Michael addition/single‐electron transfer oxidation/radical cyclization/oxygenation strategy mediated by ferrocenium hexafluorophosphate, a recyclable, less toxic single‐electron transfer oxidant. Ester enolates were coupled with α‐benzylidene and α‐alkylidene β‐dicarbonyl compounds with switchable diastereoselectivity. This pivotal steering element subsequently controls the diastereoselectivity of the radical cyclization step. The substitution pattern of the radical cyclization acceptor enables a switch of the cyclization mode from a 5‐exo pattern for terminally substituted olefin units to a 6‐endo mode for internally substituted acceptors. The oxidative anionic/radical strategy also allows efficient termination by oxygenation with the free radical 2,2,6,6‐tetramethyl‐1‐piperidinoxyl, and two CC bonds and one CO bond are thus formed in the sequence. A stereochemical model is proposed that accounts for all of the experimental results and allows the prediction of the stereochemical outcome. Further transformations of the synthesized cyclopentanes are reported.