bluuebunny/crossref_metadata_2025 huggingface dataset:
Paper‐Based Electrical Respiration Sensor
Authors: Güder Firat , Ainla Alar , Redston Julia , Mosadegh Bobak , Glavan Ana , Martin T. J. , Whitesides George M.
Published: April 2016

Current methods of monitoring breathing require cumbersome, inconvenient, and often expensive devices; this requirement sets practical limitations on the frequency and duration of measurements. This article describes a paper‐based moisture sensor that uses the hygroscopic character of paper (i.e. the ability of paper to adsorb water reversibly from the surrounding environment) to measure patterns and rate of respiration by converting the changes in humidity caused by cycles of inhalation and exhalation to electrical signals. The changing level of humidity that occurs in a cycle causes a corresponding change in the ionic conductivity of the sensor, which can be measured electrically. By combining the paper sensor with conventional electronics, data concerning respiration can be transmitted to a nearby smartphone or tablet computer for post‐processing, and subsequently to a cloud server. This means of sensing provides a new, practical method of recording and analyzing patterns of breathing.
Benzotrithiophene‐Based Hole‐Transporting Materials for 18.2 % Perovskite Solar Cells
Authors: Molina‐Ontoria Agustín , Zimmermann Iwan , Garcia‐Benito Inés , Gratia Paul , Roldán‐Carmona Cristina , Aghazada Sadig , Graetzel Michael , Nazeeruddin Mohammad Khaja , Martín Nazario
Published: April 2016

New star‐shaped benzotrithiophene (BTT)‐based hole‐transporting materials (HTM) BTT‐1, BTT‐2 and BTT‐3 have been obtained through a facile synthetic route by crosslinking triarylamine‐based donor groups with a benzotrithiophene (BTT) core. The BTT HTMs were tested on solution‐processed lead trihalide perovskite‐based solar cells. Power conversion efficiencies in the range of 16 % to 18.2 % were achieved under AM 1.5 sun with the three derivatives. These values are comparable to those obtained with today's most commonly used HTM spiro‐OMeTAD, which point them out as promising candidates to be used as readily available and cost‐effective alternatives in perovskite solar cells (PSCs).
Surface‐Guided Formation of an Organocobalt Complex
Authors: Weber Peter B. , Hellwig Raphael , Paintner Tobias , Lattelais Marie , Paszkiewicz Mateusz , Casado Aguilar Pablo , Deimel Peter S. , Guo Yuanyuan , Zhang Yi‐Qi , Allegretti Francesco , Papageorgiou Anthoula C. , Reichert Joachim , Klyatskaya Svetlana , Ruben Mario , Barth Johannes V. , Bocquet Marie‐Laure , Klappenberger Florian
Published: April 2016

Organocobalt complexes represent a versatile tool in organic synthesis as they are important intermediates in Pauson–Khand, Friedel–Crafts, and Nicholas reactions. Herein, a single‐molecule‐level investigation addressing the formation of an organocobalt complex at a solid–vacuum interface is reported. Deposition of 4,4′‐(ethyne‐1,2‐diyl)dibenzonitrile and Co atoms on the Ag(111) surface followed by annealing resulted in genuine complexes in which single Co atoms laterally coordinated to two carbonitrile groups undergo organometallic bonding with the internal alkyne moiety of adjacent molecules. Alternative complexation scenarios involving fragmentation of the precursor were ruled out by complementary X‐ray photoelectron spectroscopy. According to density functional theory analysis, the complexation with the alkyne moiety follows the Dewar–Chatt–Duncanson model for a two‐electron‐donor ligand where an alkyne‐to‐Co donation occurs together with a strong metal‐to‐alkyne back‐donation.
Tailoring Copper Nanocrystals towards C2 Products in Electrochemical CO2 Reduction
Authors: Loiudice Anna , Lobaccaro Peter , Kamali Esmail A. , Thao Timothy , Huang Brandon H. , Ager Joel W. , Buonsanti Raffaella
Published: April 2016

Favoring the CO2 reduction reaction (CO2RR) over the hydrogen evolution reaction and controlling the selectivity towards multicarbon products are currently major scientific challenges in sustainable energy research. It is known that the morphology of the catalyst can modulate catalytic activity and selectivity, yet this remains a relatively underexplored area in electrochemical CO2 reduction. Here, we exploit the material tunability afforded by colloidal chemistry to establish unambiguous structure/property relations between Cu nanocrystals and their behavior as electrocatalysts for CO2 reduction. Our study reveals a non‐monotonic size‐dependence of the selectivity in cube‐shaped copper nanocrystals. Among 24 nm, 44 nm and 63 nm cubes tested, the cubes with 44 nm edge length exhibited the highest selectivity towards CO2RR (80 %) and faradaic efficiency for ethylene (41 %). Statistical analysis of the surface atom density suggests the key role played by edge sites in CO2RR.
Covalent Self‐Assembly and One‐Step Photocrosslinking of Tyrosine‐Rich Oligopeptides to Form Diverse Nanostructures
Authors: Min Kyoung‐Ik , Yun Gyeongwon , Jang Yoonjung , Kim Kyung‐Rok , Ko Young Ho , Jang Hyung‐Seok , Lee Yoon‐Sik , Kim Kimoon , Kim Dong‐Pyo
Published: April 2016

We present covalently self‐assembled peptide hollow nanocapsule and peptide lamella. These biomimetic dityrosine peptide nanostructures are synthesized by one‐step photopolymerization of a tyrosine‐rich short peptide without the aid of a template. This simple approach offers direct synthesis of fluorescent peptide nanocages and free‐standing thin films. The simple crosslinked peptide lamella films provide robust mechanical properties with an elastic modulus of approximately 30 GPa and a hardness of 740 MPa. These nanostructures also allow for the design of peptidosomes. The approach taken here represents a rare example of covalent self‐assembly of short peptides into nano‐objects, which may be useful as microcompartments and separation membranes.
Preparation and Reactivity of Acyclic Chiral Allylzinc Species by a Zinc‐Brook Rearrangement
Authors: Leibeling Markus , Shurrush Khriesto A. , Werner Veronika , Perrin Lionel , Marek Ilan
Published: April 2016

The zinc‐Brook rearrangement of enantiomerically enriched α‐hydroxy allylsilane produces a chiral allylzinc intermediate, which reacts with retention of configuration in the presence of an electrophile. Two remarkable features of this transformation are the stereochemical outcome during the formation of the allylzinc species and the complete stereocontrol in the organized six‐membered transition state, which leads to an overall and complete transfer of chirality within the reaction sequence.
Lewis Acid Assisted Nickel‐Catalyzed Cross‐Coupling of Aryl Methyl Ethers by C−O Bond‐Cleaving Alkylation: Prevention of Undesired β‐Hydride Elimination
Authors: Liu Xiangqian , Hsiao Chien‐Chi , Kalvet Indrek , Leiendecker Matthias , Guo Lin , Schoenebeck Franziska , Rueping Magnus
Published: April 2016

In the presence of trialkylaluminum reagents, diverse aryl methyl ethers can be transformed into valuable products by C−O bond‐cleaving alkylation, for the first time without the limiting β‐hydride elimination. This new nickel‐catalyzed dealkoxylative alkylation method enables powerful orthogonal synthetic strategies for the transformation of a variety of naturally occurring and easily accessible anisole derivatives. The directing and/or activating properties of aromatic methoxy groups are utilized first, before they are replaced by alkyl chains in a subsequent coupling process.
High‐Resolution Rotational Spectroscopy Study of the Smallest Sugar Dimer: Interplay of Hydrogen Bonds in the Glycolaldehyde Dimer
Authors: Zinn Sabrina , Medcraft Chris , Betz Thomas , Schnell Melanie
Published: April 2016

Molecular recognition of carbohydrates plays an important role in nature. The aggregation of the smallest sugar, glycolaldehyde, was studied in a conformer‐selective manner using high‐resolution rotational spectroscopy. Two different dimer structures were observed. The most stable conformer reveals C2‐symmetry by forming two intermolecular hydrogen bonds, giving up the strong intramolecular hydrogen bonds of the monomers and thus showing high hydrogen bond selectivity. By analyzing the spectra of the 13C and 18O isotopologues of the dimer in natural abundance, we could precisely determine the heavy backbone structure of the dimer. Comparison to the monomer structure and the complex with water provides insight into intermolecular interactions. Despite hydrogen bonding being the dominant interaction, precise predictions from quantum‐chemical calculations highly rely on the consideration of dispersion.
Superior Electrical Conductivity in Hydrogenated Layered Ternary Chalcogenide Nanosheets for Flexible All‐Solid‐State Supercapacitors
Authors: Hu Xin , Shao Wei , Hang Xudong , Zhang Xiaodong , Zhu Wenguang , Xie Yi
Published: April 2016

As the properties of ultrathin two‐dimensional (2D) crystals are strongly related to their electronic structures, more and more attempts were carried out to tune their electronic structures to meet the high standards for the construction of next‐generation smart electronics. Herein, for the first time, we show that the conductive nature of layered ternary chalcogenide with formula of Cu2WS4 can be switched from semiconducting to metallic by hydrogen incorporation, accompanied by a high increase in electrical conductivity. In detail, the room‐temperature electrical conductivity of hydrogenated‐Cu2WS4 nanosheet film was almost 1010 times higher than that of pristine bulk sample with a value of about 2.9×104 S m−1, which is among the best values for conductive 2D nanosheets. In addition, the metallicity in the hydrogenated‐Cu2WS4 is robust and can be retained under high‐temperature treatment. The fabricated all‐solid‐state flexible supercapacitor based on the hydrogenated‐Cu2WS4 nanosheet film shows promising electrochemical performances with capacitance of 583.3 F cm−3 at a current density of 0.31 A cm−3. This work not only offers a prototype material for the study of electronic structure regulation in 2D crystals, but also paves the way in searching for highly conductive electrodes.
Dibenzo[a,j]phenazine‐Cored Donor–Acceptor–Donor Compounds as Green‐to‐Red/NIR Thermally Activated Delayed Fluorescence Organic Light Emitters
Authors: Data Przemyslaw , Pander Piotr , Okazaki Masato , Takeda Youhei , Minakata Satoshi , Monkman Andrew P.
Published: April 2016

A new family of thermally activated delayed fluorescence (TADF) emitters based on U‐shaped D‐A‐D architecture with a novel accepting unit has been developed. All investigated compounds have small singlet‐triplet energy splitting (ΔEST) ranging from 0.02 to 0.20 eV and showed efficient TADF properties. The lowest triplet state of the acceptor unit plays the key role in the TADF mechanism. OLEDs fabricated with these TADF emitters achieved excellent efficiencies up to 16 % external quantum efficiency (EQE).
Polymerization Initiated by Organic Electron Donors
Authors: Broggi Julie , Rollet Marion , Clément Jean‐Louis , Canard Gabriel , Terme Thierry , Gigmes Didier , Vanelle Patrice
Published: April 2016

Polymerization reactions with organic electron donors (OED) as initiators are presented herein. The metal‐free polymerization of various activated alkene and cyclic ester monomers was performed in short reaction times, under mild conditions, with small amounts of organic reducing agents, and without the need for co‐initiators or activation by photochemical, electrochemical, or other methods. Hence, OED initiators enabled the development of an efficient, rapid, room‐temperature process that meets the technical standards expected for industrial processes, such as energy savings, cost‐effectiveness and safety. Mechanistic investigations support an electron‐transfer initiation pathway that leads to the reduction of the monomer.
Efficient Synthesis of Molecular Precursors for Para‐Hydrogen‐Induced Polarization of Ethyl Acetate‐1‐13C and Beyond
Authors: Shchepin Roman V. , Barskiy Danila A. , Coffey Aaron M. , Manzanera Esteve Isaac V. , Chekmenev Eduard Y.
Published: April 2016

A scalable and versatile methodology for production of vinylated carboxylic compounds with 13C isotopic label in C1 position is described. It allowed synthesis of vinyl acetate‐1‐13C, which is a precursor for preparation of 13C hyperpolarized ethyl acetate‐1‐13C, which provides a convenient vehicle for potential in vivo delivery of hyperpolarized acetate to probe metabolism in living organisms. Kinetics of vinyl acetate molecular hydrogenation and polarization transfer from para‐hydrogen to 13C via magnetic field cycling were investigated. Nascent proton nuclear spin polarization (%PH) of ca. 3.3 % and carbon‐13 polarization (%P13C) of ca. 1.8 % were achieved in ethyl acetate utilizing 50 % para‐hydrogen corresponding to ca. 50 % polarization transfer efficiency. The use of nearly 100% para‐hydrogen and the improvements of %PH of para‐hydrogen‐nascent protons may enable production of 13C hyperpolarized contrast agents with %P13C of 20–50 % in seconds using this chemistry.
A Single‐Crystalline Mesoporous Quartz Superlattice
Authors: Matsuno Takamichi , Kuroda Yoshiyuki , Kitahara Masaki , Shimojima Atsushi , Wada Hiroaki , Kuroda Kazuyuki
Published: April 2016

There has been significant interest in the crystallization of nanostructured silica into α‐quartz because of its physicochemical properties. We demonstrate a single‐crystalline mesoporous quartz superlattice, a silica polymorph with unprecedentedly ordered hierarchical structures on both the several tens of nanometers scale and the atomic one. The mesoporous quartz superlattice consists of periodically arranged α‐quartz nanospheres whose crystalline axes are mostly oriented in an assembly. The superlattice is prepared by thermal crystallization of amorphous silica nanospheres constituting a colloidal crystal. We found that the deposition of a strong flux of Li+ only on the surface of silica nanospheres is effective for crystallization.
Readily Accessible Bulky Iron Catalysts exhibiting Site Selectivity in the Oxidation of Steroidal Substrates
Authors: Font David , Canta Mercè , Milan Michela , Cussó Olaf , Ribas Xavi , Klein Gebbink Robertus J. M. , Costas Miquel
Published: April 2016

Bulky iron complexes are described that catalyze the site‐selective oxidation of alkyl C−H bonds with hydrogen peroxide under mild conditions. Steric bulk at the iron center is introduced by appending trialkylsilyl groups at the meta‐position of the pyridines in tetradentate aminopyridine ligands, and this effect translates into high product yields, an enhanced preferential oxidation of secondary over tertiary C−H bonds, and the ability to perform site‐selective oxidation of methylenic sites in terpenoid and steroidal substrates. Unprecedented site selective oxidation at C6 and C12 methylenic sites in steroidal substrates is shown to be governed by the chirality of the catalysts.
Dysprosium(III)‐Catalyzed Ring‐Opening of meso‐Epoxides: Desymmetrization by Remote Stereocontrol in a Thiolysis/Elimination Sequence
Authors: Yao Lu , Zhu Qiao , Wei Liang , Wang Zuo‐Fei , Wang Chun‐Jiang
Published: April 2016

An unprecedented asymmetric desymmetrization of meso‐epoxides, derived from cyclopentene‐1,3‐diones, with 2‐mercaptobenzothiazoles has been realized. It was efficiently catalyzed by a chiral DyIII/N,N′‐dioxide complex through a thiolysis/elimination sequence. This remote stereocontrol strategy provides facile access to synthetically versatile cyclopentene derivatives bearing an all‐carbon quaternary stereogenic center in high yield and excellent enantioselectivity. Intriguingly, optically active thiophene could be readily generated from the obtained product through an efficient one‐pot protocol.
The Bis(pentafluoroethyl)germylene Trimethylphosphane Adduct (C2F5)2Ge⋅PMe3: Characterization, Ligand Properties, and Reactivity
Authors: Pelzer Stefanie , Neumann Beate , Stammler Hans‐Georg , Ignat'ev Nikolai , Hoge Berthold
Published: April 2016

The synthesis of the germylene phosphane adduct (C2F5)2Ge⋅PMe3 is described. Starting from (C2F5)3GeH in an excess of PMe3, heating was applied, whereupon reductive elimination of C2F5H occurred. The molecular structure was ascertained by X‐ray diffraction and compared with information obtained by quantum chemical methods. The ligand properties were derived by studying the IR spectrum of the nickel(0) complex [Ni(CO)3{Ge(C2F5)2(PMe3)}] in the CO region. (C2F5)2Ge⋅PMe3 turned out to be a π‐accepting ligand comparable to PMe3, in terms of Tolman's electronic parameter. Furthermore a [2+4] cycloaddition reaction with 2,3‐dimethyl‐1,3‐butadiene, and σ‐bond insertion reactions were recorded. Activation of the C−Cl bond in dichloromethane gives rise to the formation of the phosphonium ylide complex [(C2F5)2Cl2Ge‐CH2PMe3], which was fully characterized by X‐ray diffraction.
Broad‐Spectrum Liquid‐ and Gas‐Phase Decontamination of Chemical Warfare Agents by One‐Dimensional Heteropolyniobates
Authors: Guo Weiwei , Lv Hongjin , Sullivan Kevin P. , Gordon Wesley O. , Balboa Alex , Wagner George W. , Musaev Djamaladdin G. , Bacsa John , Hill Craig L.
Published: April 2016

A wide range of chemical warfare agents and their simulants are catalytically decontaminated by a new one‐dimensional polymeric polyniobate (P‐PONb), K12[Ti2O2][GeNb12O40]⋅19 H2O (KGeNb) under mild conditions and in the dark. Uniquely, KGeNb facilitates hydrolysis of nerve agents Sarin (GB) and Soman (GD) (and their less reactive simulants, dimethyl methylphosphonate (DMMP)) as well as mustard (HD) in both liquid and gas phases at ambient temperature and in the absence of neutralizing bases or illumination. Three lines of evidence establish that KGeNb removes DMMP, and thus likely GB/GD, by general base catalysis: a) the k(H2O)/k(D2O) solvent isotope effect is 1.4; b) the rate law (hydrolysis at the same pH depends on the amount of P‐PONb present); and c) hydroxide is far less active against the above simulants at the same pH than the P‐PONbs themselves, a critical control experiment.
Well‐Defined Models for the Elusive Dinuclear Intermediates of the Pauson–Khand Reaction
Authors: Hartline Douglas R. , Zeller Matthias , Uyeda Christopher
Published: April 2016

The mechanism of the Pauson–Khand reaction has attracted significant interest due to the unusual dinuclear nature of the Co2(CO)x active site. Experimental and computational data have indicated that the intermediates following the initial Co2(CO)6(alkyne) complex are thermodynamically unstable and do not build up in appreciable concentrations during the course of the reaction. As a consequence, the key steps that control the scope of viable substrates and various aspects of selectivity have remained largely uncharacterized. Herein, a direct experimental investigation of the dinuclear metallacycle‐forming step of the Pauson–Khand reaction is reported. These studies capitalize on well‐defined d9–d9 dinickel complexes supported by a naphthyridine–diimine (NDI) pincer ligand as functional surrogates of Co2(CO)8.
Visible‐Light‐Driven Water Oxidation by a Molecular Manganese Vanadium Oxide Cluster
Authors: Schwarz Benjamin , Forster Johannes , Goetz McKenna K. , Yücel Duygu , Berger Claudia , Jacob Timo , Streb Carsten
Published: April 2016

Photosynthetic water oxidation in plants occurs at an inorganic calcium manganese oxo cluster, which is known as the oxygen evolving complex (OEC), in photosystem II. Herein, we report a synthetic OEC model based on a molecular manganese vanadium oxide cluster, [Mn4V4O17(OAc)3]3−. The compound is based on a [Mn4O4]6+ cubane core, which catalyzes the homogeneous, visible‐light‐driven oxidation of water to molecular oxygen and is stabilized by a tripodal [V4O13]6− polyoxovanadate and three acetate ligands. When combined with the photosensitizer [Ru(bpy)3]2+ and the oxidant persulfate, visible‐light‐driven water oxidation with turnover numbers of approximately 1150 and turnover frequencies of about 1.75 s−1 is observed. Electrochemical, mass‐spectrometric, and spectroscopic studies provide insight into the cluster stability and reactivity. This compound could serve as a model for the molecular structure and reactivity of the OEC and for heterogeneous metal oxide water‐oxidation catalysts.
Predicting and Screening Dielectric Transitions in a Series of Hybrid Organic–Inorganic Double Perovskites via an Extended Tolerance Factor Approach
Authors: Shi Chao , Yu Chun‐Hua , Zhang Wen
Published: April 2016

Extended Goldschmidt tolerance factor t is applied to the hybrid double perovskites (MA)2[B′B′′(CN)6] (MA=methylammonium cation) to predict and screen dielectric transitions in 121 compounds through the correlations among t, the radius of the B component rB and the transition temperature Tc, based on experimental results from model compounds. For (MA)2[B′Co(CN)6], it is concluded that: i) when t>0.873, the cubic phase would be stable below 298 K; ii) when 0.873>t>0.805, the cubic phase would be stable between 298 and 523 K; iii) the larger the rB, the higher the Tc of the perovskite (Tc1/2∝rB); and iv) the Tc of the hybrid perovskites can be well tuned by doping the B components.
Are biofuels sustainable? An LCA/multivariate perspective on feedstocks and processes
Authors: Russo Valentina , Paola Luisa Di , Piemonte Vincenzo , Basile Angelo , Falco Marcello De , Giuliani Alessandro
Published: April 2016

Liquid biofuels represent a valid option for traditional fossil liquid fuels, but their sustainability is still under enquiry. In this work, we merge the Life‐Cycle‐Assessment methods with the Multivariate Statistic Analysis (MVA), to define a general methodology to compare biofuels derived from different feedstocks and fossil fuels. We tried to assess in an unambiguous way whether the biofuels are more sustainable than liquid fuels, in terms of both emissions and depletion of non‐renewable sources. Whereas first generation products present even higher environmental impacts than fossil fuels, which in turn rely on consolidated, optimized processes, whose environmental footprint and yields have been improved over the years. Our results trace a good sustainability profile for second generation biofuels, especially for biogas that seems to be the best trade‐off both from a LCA perspective and as a single dimensionless score derived from the MVA. © 2016 Curtin University of Technology and John Wiley & Sons, Ltd.
Experimental study on film thickness and the problem of free surface film flow in dip coating
Authors: Chen Meng Meng , Zhang Xian Ming , Ma Jian Ping , Chen Shi Chang , Chen Wen Xing , Feng Lian Fang
Published: April 2016

Dip coating is widely applied in industries for coating a solid substrate with a fluid because of its simplicity and applicability to substrates with different shapes. An experimental study was reported with dip coater on the film coating of solid plates by withdrawal from a tank filled with silicone oil fluids or polyacrylic acid (PAA) solutions with different rheological properties, the liquid film thickness deposited on the plate substrate was measured using capacitance method, and the evolution of free surface morphology was recorded with photographs. The purpose was to investigate the effects of plate substrate roughness, withdrawal speed, rest time, and fluid viscosity on the liquid film thickness and free surface morphology in detail. Results showed that the increases in coating fluid viscosity, withdrawal speed, and substrate roughness are beneficial to film thickening. The influence of rest time on liquid film thickness could be neglected when it was greater than 3 min. For silicone oil fluids, the free surface exhibited a depression, which gradually deepened, with the increasing in withdrawal speed and viscosities. By contrast, PAA solutions showed a bump on the free surface, exhibiting a curvature that increased with the increasing in withdrawal speed and concentrations. © 2016 Curtin University of Technology and John Wiley & Sons, Ltd.
Influence of modification process parameters on the properties of crumb rubber/EVA modified asphalt
Authors: Fang Changqing , Qiao Xiaoting , Yu Ruien , Yu Xin , Liu Jianjun , Yu Jiang , Xia Ronghou
Published: April 2016

Crumb rubber (CR) and ethylene vinyl acetate copolymer (EVA) were adopted as asphalt modifiers. Routine tests, softening point, penetration, and ductility were used to evaluate the basic properties of crumb rubber and ethylene vinyl acetate copolymers (CR/EVA) modified asphalt. The segregation experiment measured the storage stability. Modern test methods such as fluorescence microscopic photography technology was used to study stability of polymer modified asphalt. Infrared spectrum experiment was used to analyze the composition differences of the upper part and lower part of CR/EVA modified asphalt. Matlab software was employed to fit out the formulae of ductility, penetration, and softening point difference of modified asphalt and shearing temperature, shearing time and shearing rate separately. Compared with base asphalt, the properties of CR/EVA modified asphalt have been greatly improved. The formulae which were fitted out by Matlab software showed that the shearing time was the foremost factor affecting the properties of CR/EVA modified asphalt, followed by shearing temperature, and the last was shearing rate. The conclusions which were fitted by orthogonal experiment were basically consistent with the results of formulae which were fitted out by Matlab software. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43598.
Chemical evaluation of composites natural rubber/carbon black/leather tannery projected to antistatic flooring
Authors: Ruiz Marcos Roberto , Cabreira Pedro Luiz Sobreiro , Budemberg Eduardo Roque , Reis Elton Aparecido Prado dos , Bellucci Felipe Silva , Job Aldo Eloizo
Published: April 2016

In this study the composites which are commonly called NR/CB/Leather were developed in order to apply them as antistatic flooring and coating. They were developed using vulcanized natural rubber, carbon black to add an electric conduction property and industrial leather waste. The leather industrial waste was micronized and added to the rubber matrix in proportions of 60 and 80 phr using an opened mixing cylinder according to ASTM D 3182 standard. The composites were exposed to the sanitizing agents, (i) bleach and (ii) disinfectant, aiming to simulate a real cleaning context, and to meet the health standards of the Brazilian Ministry of health. Physical‐chemical and microbiological evaluations were carried out to determine the structural and chemical stabilities of the composites. After this, low water absorption level (<1.5%), immobilization and low chromium oxide level (<1.5), pH within the neutrality rate and an excellent resistance to microbiological contamination were identified for the composites. Thus, from a physical‐chemical perspective, the composites NR/CB/Leather displayed suitable properties and potential for application as antistatic flooring and coatings. Besides using leather industrial waste in their production, their manufacture can boost this industrial sector economically and, consequently, promote a reduction in environmental impact. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43618.
α‐Thiophene end‐capped styrene copolymer containing fullerene pendant moieties: Synthesis, characterization, and gas sensing properties
Authors: Şennik Erdem , Şennik Büşra , Alev Onur , Kılınç Necmettin , Yilmaz Faruk , Ziya Öztürk Zafer
Published: April 2016

We report the synthesis, characterization, and gas sensing properties of a styrene copolymer bearing α‐thiophene end group and fullerene (C60) pendant moieties P(S‐co‐CMS‐C60). First, the copolymer of styrene (S) and chloromethylstyrene (CMS) monomers was prepared in bulk via a bimolecular nitroxide‐mediated radical polymerization (NMP) technique using benzoyl peroxide (BPO) as the radical initiator and nitroxy‐functional thiophene compound (Thi‐TEMPO) as the co‐radical and this gave α‐thiophene end‐capped copolymer P(S‐co‐CMS). The chloromethylstyrene units of P(S‐co‐CMS) allowed further side‐chain functionalization onto P(S‐co‐CMS). The obtained P(S‐co‐CMS) was then reacted with sodium azide (NaN3) and this led to the copolymer with pendant azide groups, P(S‐co‐CMS‐N3), and then grafted with electron‐acceptor C60 via the reaction between N3 and C60. The final product was characterized by using NMR, FTIR, and UV–vis methods. Electrical characterization of P(S‐co‐CMS‐C60) thin film was also investigated at between 30 and 100 °C as the ramps of 10 °C. Temperature dependent electrical characterization results showed that P(S‐co‐CMS‐C60) thin film behaves like a semiconductor. Furthermore, P(S‐co‐CMS‐C60) was employed as the sensing layer to investigate triethylamine (TEA), hydrogen (H2), acetone, and ethanol sensing properties at 100 °C. The results revealed that P(S‐co‐CMS‐C60) thin film has a sensing ability to H2. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43641.
Tara tannin as active ingredient in electrospun fibrous delivery system
Authors: Sunthornvarabhas Jackapon , Liengprayoon Siriluck , Aouf Chahinez , Rungjang Walaiporn , Sangseethong Kunruedee , Lecomte Jerome , Suwonsichon Thongchai , Boonreungrod Chutima , Dubreucq Eric , Fulcrand Helene
Published: April 2016

This study evaluated the releasing performance of tara tannin, a cocktail of plant polyphenols, incorporated in submicron fiber, produced by the electrospinning process. Polylactic acid was used as a polymer matrix that carried two loading levels of tara tannin, 14.3 and 22.3% dry weight in the final product. The fiber diameter of composite fibers was in the range 500–700 nm. The release of tara tannin was controlled by material attachment as there was no evidence of chemical bonding between materials. This was further confirmed by FTIR and DSC. From the five combinations of acid that were presented in tara tannin, galloylquinic acid, with the smallest molecular weight composition, was released in the largest proportion (%molar) and exhibited antioxidant activity. This was confirmed by 2,2‐diphenyl‐1‐picrylhydrazyl assay and HPLC‐MS analyses. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43646.
Acrylic‐based epoxy resin damping systems: Synthesis, characterization, and properties
Authors: Yang Yuan , Zhao Yun‐Feng , Wang Jian‐Yue , Zhao Chuan , Tong Liu , Liu Xiao‐Yan , Zhan Mao‐Sheng
Published: April 2016

Acrylate‐based epoxy resin (AE)/low molecular weight polyamine (LPA) composites were developed. The chemical structure, curing behavior, fracture morphology, damping properties, and mechanical properties were evaluated by Fourier transform infrared (FTIR),1H‐nuclear magnetic resonance (1H‐NMR), gel permeation chromatography (GPC), Differential scanning calorimeter (DSC), scanning electron microscope (SEM), Dynamic mechanical thermal analysis (DMTA), and electro mechanical machine. Transmission electron microscope (TEM) and SEM pictures exhibited nanoscale micro‐phase separation between epoxy and acrylic segmers. DMTA results indicated that the loss factor of cured AE/LPA system could reach 1.84 and temperature range of tan δ > 0.5 was about 84 °C. Tensile strength and elongation at break of the cured AE samples can reach 6.5 MPa and 185%, respectively. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci.2016,133, 43654.
Effects of TiO2, ZnO, and Fe3O4 nanofillers on rheological behavior, microstructure, and reaction kinetics of rigid polyurethane foams
Authors: Akkoyun Meral , Suvaci Ender
Published: April 2016

Effects of different types and shapes of titanium dioxide, zinc oxide, and magnetite nanofillers on the rheological behavior of polyol/nanofiller suspensions, on the rigid polyurethane foam formation reaction, and hence on the final microstructure were investigated. The rheological percolation threshold of polyol/nanofiller suspensions decreased as the aspect ratio of nonspherical nanoparticles (platelet or rod) increased, regardless of the nanofiller type. The results of reaction kinetics showed that above a critical surface area (≈30 m2), independently of nanofiller type, the reaction rate increased as the surface area increased. The introduction of oxide surfaces reduced the final cell size until a critical surface area (≈30 m2). However, above this critical value cell size distribution gets wider and the cell size can no longer be correlated with the surface area. In the latter case, an increase of the reaction rate and the polymerization reaction being exothermic may facilitate uncontrolled cell nucleation, growth, and hence coalescence which results in an uncontrolled foam structure. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43658.
Poly(propylene carbonate) polyurethane self‐polishing coating for marine antifouling application
Authors: Chen Yongyue , Liu Zhixiong , Han Sheng , Han Jin , Jiang Daoyi
Published: April 2016

In this contribution, a series of environmentally friendly thermoplastic poly(propylene carbonate) polyurethane (PPCU) were prepared by two‐step condensation polymerization and used to fabricate antifouling coatings. The poly(propylene carbonate) (PPC) segments served as degradable moieties. Quartz crystal microbalance with dissipation (QCM‐D) measurements revealed that the polyurethane could degrade in the presence of enzyme and the degradation rate increases with the decrease of the molecular weight of the polyurethane. Investigation on the hydrolytic degradation behavior and the release rate test of the antifoulants in artificial seawater also demonstrated that the hydrolysis rate and the release rate increased as the molecular weight decreased, which makes the coating controllable at the hydrolysis rate range of 0.012–0.051 g/(m2d). Marine field tests and algae settlement assay tests revealed that the polyurethane coating possessed antibiofouling ability due to its self‐renewal property and the release of antifoulants. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43667.
Biodegradable composites with improved barrier properties and transparency from the impregnation of PLA to bacterial cellulose membranes
Authors: Urbina Leire , Algar Itxaso , García‐Astrain Clara , Gabilondo Nagore , González Alba , Corcuera MaAngeles , Eceiza Arantxa , Retegi Aloña
Published: April 2016

Poly(lactic acid) (PLA) was impregnated in bacterial cellulose (BC) membranes. BC/PLA films were prepared by solvent casting and mechanical, optical and barrier properties, and biodegradation process were investigated. The transparency of processed films was higher than that of neat BC and increased with PLA content. Moreover, the incorporation of PLA to BC enhanced significantly the water vapor barrier properties of the BC membranes. The bionanocomposites contained a high percentage of cellulose due to the impregnation method that leads to the film with a BC content of 94%, which practically maintains the excellent mechanical properties of BC. However, when increasing the PLA content in the bionanocomposites the mechanical properties decreased slightly with respect to BC. Biodegradation under real soil conditions was determined indirectly through the study of the visual degradation and disintegration, demonstrating that the bionanocomposites were degraded faster than the neat PLA. The successful production of BC/PLA bionanocomposites suggested the possible application of them for active food packaging. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43669.
Effect of molecular rigidity and hydrogen bond interaction on mechanical properties of polyimide fibers
Authors: Feng Yan , Luo Long Bo , Huang Jieyang , Li Ke , Li Baoying , Wang Huina , Liu Xiangyang
Published: April 2016

Six kinds of polyimide (PI) fibers with different molecular rigidity and hydrogen bond interactions were designed and prepared in order to investigate the relationship between structure and mechanical properties. The rigidity, aggregation structure, fracture morphology, hydrogen bond, and charge transfer (CT) interactions were investigated in detail. Conformational rigidity of six PI fibers were simulated and measured byD‐values of energy barrier and bottom in potential energy curves of PI units. Rigid rod‐like PI macromolecules tend to pack in order and show better mechanical properties. However, with the increase ofD‐values, fracture mechanisms change from ductile fracture to brittle fracture. Brittle fracture resulting from high conformational rigidity is adverse to improvement of mechanical properties of PI fibers. Besides, strength of hydrogen bond and CT interactions are characterized by infrared spectroscopy and ultraviolet absorption spectra, respectively. The results indicate that higher interactions lead to higher tensile strength and initial modulus. Finally, PI fibers, which possess moderate conformational rigidity and strong hydrogen bond interactions, exhibit highest tensile strength (1.82 GPa) and initial modulus (85.7 GPa) in six kinds of PI fibers. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci.2016,133, 43677.
Continuous aligned poly(meta‐phenylene isophthalamide) fibers via stable jet electrospinning
Authors: Chen Weiwang , Weng Wenguo
Published: April 2016

Continuous aligned poly(meta‐phenylene isophthalamide) (PMIA) fibers are first fabricated by Stable Jet Electrospinning (SJES) with a collection distance of 15 cm. The unfolded length of every single fiber is calculated to be several hundred to several thousand meters. Morphology analysis by field emission scanning electron microscopy (FE‐SEM) shows that these fibers are well arranged and uniformly distributed and their average fiber diameters decrease gradually with increasing collection speed. The effects of ambient temperature and humidity on the duration of stable jet are also discussed. Moderate temperatures and humidity are preferred for fabricating PMIA fibers with ultra‐long size. Besides, the changes of the thermal and crystalline properties of PMIA fibers are also investigated. The significant decline in crystallinity should be responsible for its decreased thermal property. Further improvements to its thermal and crystalline performance must be given consideration in future applications. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43690.
Macro‐mechanism of polyvinyl chloride shrink sleeves embossed marking
Authors: Kondratov Alexander P. , Volinsky Alex A. , Chen Jia
Published: April 2016

Mechanism description and the physical model of shrink sleeve relief labeling are presented. Embossed letters and symbols on goods packaging are intended for people with impaired vision, capable of recognizing tactile Braille marking. Internal stresses relaxation in shrink films made of rigid polyvinyl chloride at various stages of thermal printing is quantified. Dependencies between the relief parameters, the Braille font pixel diameter, and the gap between the container and the tubular film label are established. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43691.
Habitat use by two extremophile, highly endemic, and critically endangered fish species (Gambusia eurystoma and Poecilia sulphuraria; Poeciliidae)
Authors: Culumber Zachary W. , Hopper Garrett W. , Barts Nicholas , Passow Courtney N. , Morgan Samuel , Brown Anthony , Arias‐Rodriguez Lenin , Tobler Michael
Published: April 2016

Effective conservation measures for endangered species require basic knowledge of habitat use and critical environmental variables influencing the species' occurrence. However, setting priorities may be difficult when multiple endangered species inhabit the same area and differ in habitat use.

This study characterized the physical and chemical environment at 30 sites along a 2.5 km stretch of stream associated with the Baños del Azufre hydrogen sulphide spring complex, home to the only population of the widemouth gambusia (Gambusia eurystoma) in existence. Also present in the spring is Poecilia sulphuraria, a narrowly endemic and endangered species known from only a few populations. This study provides the most detailed report to date for physical and chemical drivers of species density in this small, extreme environment.

Gambusia eurystoma were generally rare throughout the stream, and stream flow and substrate size were the best predictors of G. eurystoma densities. Conversely, P. sulphuraria were considerably more abundant, but no physical or chemical variables predicted their density among sites. Size distributions of adult P. sulphuraria were significantly influenced by stream flow and water chemistry, indicating a cost to living in greater proximity to toxic springs with high hydrogen sulphide concentrations.

Overall, the results provide the first extensive report of environmental variation and factors associated with G. eurystoma densities, and indicate that conservation measures prioritizing environmental conditions for G. eurystoma will also benefit P. sulphuraria. Fish in sulphide springs provide prime examples of narrowly endemic species in desperate need of conservation, and their habitats face conservation challenges similar to those found in other springs with sympatric, endemic species in the world's arid regions.

Copyright © 2016 John Wiley & Sons, Ltd.
Re‐evaluating the timing of the Indonesian trepang industry in north‐west Arnhem Land: chronological investigations at Malara (Anuru Bay A)
Authors: WESLEY DARYL , O'CONNOR SUE , FENNER JACK N.
Published: April 2016

The Malara (Anuru Bay A) Macassan trepang‐processing site was investigated from 2008 to 2010, to test two chronological models of the timing of cultural contact between north‐west Arnhem Land and South‐East Asia. Currently, the models of contact between South‐East Asian people and Australian Indigenous people are a “long model” of pre‐Macassan and Macassan contact (>200 years) and a “short model” of only Macassan contact (<120 years). The aims of this study were to assess when the site was first occupied, when intensification of site use occurred and when the site was abandoned. This assessment was undertaken by radiocarbon dating of the major trepang‐processing features, the two burials at the site and several other occupation areas. Bayesian analysis of the 18 radiocarbon dates gives 80% probability that Indonesians first used the site around AD 1637. Trepang processing intensified during the middle to late eighteenth century, consistent with the known expansion of the Macassan trepang trade. There is a final occupation and processing phase in the late nineteenth century. We discuss issues regarding the “old” radiocarbon dates from trepang‐processing sites. We argue that our investigations support the “long model” of cultural contact between Asian visitors and local Indigenous groups.
Quinoxaline‐Based Scaffolds Targeting Tyrosine Kinases and Their Potential Anticancer Activity
Authors: El Newahie Aliya M. S. , Ismail Nasser S. M. , Abou El Ella Dalal A. , Abouzid Khaled A. M.
Published: April 2016

Quinoxaline derivatives, also called benzopyrazines, are an important class of heterocyclic compounds. Quinoxalines have drawn great attention due to their wide spectrum of biological activities. They are considered as an important basis for anticancer drugs due to their potential activity as protein kinase inhibitors. In this review, we focus on the chemistry of the quinoxaline derivatives, the strategies for their synthesis, their potential activities against various tyrosine kinases, and on the structure–activity relationship studies reported to date.
Quantification and Impact of Secondary Osteoarthritis in Patients With Anti–Citrullinated Protein Antibody–Positive Rheumatoid Arthritis
Authors: Figueiredo Camille P. , Simon David , Englbrecht Matthias , Haschka Judith , Kleyer Arnd , Bayat Sara , Hueber Axel , Pereira Rosa M. R. , Rech Juergen , Schett Georg
Published: April 2016

Objective

To search for evidence of secondary osteoarthritis (OA) in patients with rheumatoid arthritis (RA) in a cross‐sectional and longitudinal setting, and to relate osteophyte formation to functional outcome.

Methods

Anti–citrullinated protein antibody (ACPA)–positive RA patients underwent high‐resolution peripheral quantitative computed tomography of the hand. Cross‐sectional and longitudinal measurements were performed. The number and size (volume) of osteophytes as well as bone erosions were documented. The relationship of osteophytes to bone erosions and to demographic and disease‐specific data was evaluated by multiple logistic regression models.

Results

A total of 202 ACPA‐positive RA patients were enrolled in the cross‐sectional part of the study, and a total of 77 ACPA‐positive RA patients were enrolled in the longitudinal analysis (interval of 1.5 years between baseline and follow‐up assessment). The mean ± SD number of osteophytes per patient was 1.3 ± 2.3, and the mean ± SD osteophyte volume per patient was 2.6 ± 4.9 mm3. The total number of erosions was significantly correlated with the total number of osteophytes (P < 0.001), and the total volume of erosions was significantly correlated with the total volume of osteophytes (P < 0.001). Moreover, the number of osteophytes was related to age (P < 0.001) and disease duration (P = 0.001), while the volume of osteophytes was related to age (P = 0.001), disease duration (P < 0.001), and function as measured by the Health Assessment Questionnaire (P = 0.013). Multivariate regression analyses showed an independent association between osteophytes and erosions. In the longitudinal analysis, the mean number (P = 0.033) and volume (P < 0.001) of osteophytes increased significantly in RA patients during their disease course.

Conclusion

Age, disease duration, and bone erosions are associated with osteophytes, indicating development of secondary OA in patients with RA.
Association Between Overweight and Obesity and Risk of Clinically Diagnosed Knee, Hip, and Hand Osteoarthritis: A Population‐Based Cohort Study
Authors: Reyes Carlen , Leyland Kirsten M. , Peat George , Cooper Cyrus , Arden Nigel K. , Prieto‐Alhambra Daniel
Published: April 2016

Objective

Studies of previous cohorts have demonstrated an association between a status of overweight/obesity and the presence of knee and hand osteoarthritis (OA). However, no data on the effect of these factors on the OA burden are available. The aim of the present study was to analyze the effect of being overweight or obese on the incidence of routinely diagnosed knee, hip, and hand OA.

Methods

The study was conducted in a population‐based cohort using primary care records from the Sistema d'Informació per al Desenvolupament de l'Investigació en Atenció Primària database (>5.5 million subjects, covering >80% of the population of Catalonia, Spain). Participants were subjects ages ≥40 years who were without a diagnosis of OA on January 1, 2006 and had available body mass index (BMI) data. All subjects were followed up from January 1, 2006 to December 31, 2010 or to the time of loss to follow‐up or death. Measures included the World Health Organization categories of BMI (exposure), and incident clinical diagnoses of knee, hip, or hand OA according to International Classification of Diseases, Tenth Revision codes.

Results

In total, 1,764,061 subjects were observed for a median follow‐up period of 4.45 years (interquartile range 4.19–4.98 years). Incidence rates (per 1,000 person‐years at risk) of knee, hip, and hand OA were 3.7 (99% confidence interval [99% CI] 3.6–3.8), 1.7 (99% CI 1.7–1.8), and 2.6 (99% CI 2.5–2.7), respectively, among subjects in the normal weight category, and 19.5 (99% CI 19.1–19.9), 3.8 (99% CI 3.7–4.0), and 4.0 (99% CI 3.9–4.2), respectively, in those with a classification of grade II obesity. Compared to subjects with normal weight, being overweight or obese increased the risk of OA at all 3 joint sites, especially at the knee. A status of overweight, grade I obesity, and grade II obesity increased the risk of knee OA by a factor of 2‐fold, 3.1‐fold, and 4.7‐fold, respectively.

Conclusion

Being overweight or obese increases the risk of hand, hip, and knee OA, with the greatest risk in the knee, and this occurs on a dose‐response gradient of increasing BMI.