bluuebunny/crossref_metadata_2025_split huggingface dataset:
Röhrenförmige Selbstorganisation kovalenter organischer Netzwerke
Authors: Gole Bappaditya , Stepanenko Vladimir , Rager Sabrina , Grüne Matthias , Medina Dana D. , Bein Thomas , Würthner Frank , Beuerle Florian 
Published: October 2017

AbstractTrotz erheblicher Fortschritte bei der Synthese kovalenter organischer Netzwerke (COFs) wurde für diese Materialien bis jetzt nur sporadisch über den präzisen Aufbau von templatfreien Nano‐ und Mikrostrukturen berichtet. Auf der Suche nach farbstoffhaltigen porösen Materialien konnte ein neues konjugiertes Netzwerk, DPP‐TAPP‐COF, durch reversible Iminkondensationen zwischen 5,10,15,20‐Tetrakis(4‐aminophenyl)porphyrin (TAPP) und einem Diketopyrrolopyrrol‐Dialdehyd (DPP) synthetisiert werden, das eine verstärkte Absorption bis zu λ=800 nm aufweist. Überraschenderweise wurde für dieses COF eine spontane Aggregation zu hohlen Mikroröhren mit äußeren und inneren Durchmessern von d≈300 und 90 nm beobachtet. Detaillierte mechanistische Studien ergaben, dass sich zunächst schichtartige Agglomerate bilden, die mit der Zeit in röhrenförmige Mikrostrukturen transformiert werden.
Mesoporous Carbon@Titanium Nitride Hollow Spheres as an Efficient SeS2 Host for Advanced Li–SeS2 Batteries
Authors: Li Zhen , Zhang Jintao , Guan Bu Yuan , Lou Xiong Wen (David) 
Published: October 2017

AbstractThe introduction of a certain proportion of selenium into sulfur‐based cathodes is an effective strategy for enhancing the integrated battery performance. However, similar to sulfur, selenium sulfide cathodes suffer from poor cycling stability owing to the dissolution of reaction intermediate products. In this study, to exploit the advantages of SeS2 to the full and avoid its shortcomings, we designed and synthesized a hollow mesoporous carbon@titanium nitride (HMC@TiN) host for loading 70 wt % of SeS2 as a cathode material for Li–SeS2 batteries. Benefiting from both physical and chemical entrapment by hollow mesoporous carbon and TiN, the HMC@TiN/SeS2 cathode manifests high utilization of the active material and excellent cycling stability. Moreover, it exhibits promising areal capacity (up to 4 mAh cm−2) with stable cell performance in the high‐mass‐loading electrode.
Layer‐by‐Layer Assembled Conductive Metal–Organic Framework Nanofilms for Room‐Temperature Chemiresistive Sensing
Authors: Yao Ming‐Shui , Lv Xiao‐Jing , Fu Zhi‐Hua , Li Wen‐Hua , Deng Wei‐Hua , Wu Guo‐Dong , Xu Gang 
Published: October 2017

AbstractThe utility of electronically conductive metal–organic frameworks (EC‐MOFs) in high‐performance devices has been limited to date by a lack of high‐quality thin film. The controllable thin‐film fabrication of an EC‐MOF, Cu3(HHTP)2, (HHTP=2,3,6,7,10,11‐hexahydroxytriphenylene), by a spray layer‐by‐layer liquid‐phase epitaxial method is reported. The Cu3(HHTP)2 thin film can not only be precisely prepared with thickness increment of about 2 nm per growing cycle, but also shows a smooth surface, good crystallinity, and high orientation. The chemiresistor gas sensor based on this high‐quality thin film is one of the best room‐temperature sensors for NH3 among all reported sensors based on various materials.
Antibacterial Narrow‐Band‐Gap Conjugated Oligoelectrolytes with High Photothermal Conversion Efficiency
Authors: Wang Bing , Feng Guangxue , Seifrid Martin , Wang Ming , Liu Bin , Bazan Guillermo C. 
Published: October 2017

AbstractTwo conjugated oligoelectrolytes (COEs), WMG1 and WMG2, were designed with the goal of achieving near infrared absorption and high photothermal conversion efficiency. Specifically, electron‐rich thiophene and electron‐poor benzo[1,2‐c:4,5‐c′]bis[1,2,5]thiadiazole subunits were introduced into the conjugated core to modulate the optical gap and to reduce the fluorescence emission efficiency. WMG1 and WMG2 show absorption maxima at around 800 nm, which favors tissue penetration. Although relatively small in size, WMG1 and WMG2 exhibit photothermal conversion efficiencies of circa 60 % and 54 %, respectively. WMG1 shows dark toxicity to the Gram positive bacterium B. subtilis and good photothermal killing efficiency toward both B. subtilis and Gram negative E. coli, features that demonstrate the promising potential of the COE molecular design for photothermal applications.
Are There Carbenes in N‐Heterocyclic Carbene Organocatalysis?
Authors: Gehrke Sascha , Hollóczki Oldamur 
Published: October 2017

AbstractAzolium cations are widely employed in organocatalysis to catalyse highly valuable synthetic processes in the presence of a base. These reactions are called “N‐heterocyclic carbene catalysis”, based on the assumption that they are initiated by the formation of a free carbene through deprotonation, which can then react with the substrates and thereby affect their reactivity to obtain the desired products. However, we herein provide evidence that an electrophilic aromatic substitution mechanism is energetically more favourable, in which the azolium cation reacts directly with the substrate, avoiding the formation of the free carbene in solution.
Quantitative Prediction of Rate Constants for Aqueous Racemization To Avoid Pointless Stereoselective Syntheses
Authors: Ballard Andrew , Ahmad Hiwa O. , Narduolo Stefania , Rosa Lucy , Chand Nikki , Cosgrove David A. , Varkonyi Peter , Asaad Nabil , Tomasi Simone , Buurma Niklaas J. , Leach Andrew G. 
Published: October 2017

AbstractRacemization has a large impact upon the biological properties of molecules but the chemical scope of compounds with known rate constants for racemization in aqueous conditions was hitherto limited. To address this remarkable blind spot, we have measured the kinetics for racemization of 28 compounds using circular dichroism and 1H NMR spectroscopy. We show that rate constants for racemization (measured by ourselves and others) correlate well with deprotonation energies from quantum mechanical (QM) and group contribution calculations. Such calculations thus provide predictions of the second‐order rate constants for general‐base‐catalyzed racemization that are usefully accurate. When applied to recent publications describing the stereoselective synthesis of compounds of purported biological value, the calculations reveal that racemization would be sufficiently fast to render these expensive syntheses pointless.
Rhodium(II)‐ or Copper(I)‐Catalyzed Formal Intramolecular Carbene Insertion into Vinylic C(sp2)−H Bonds: Access to Substituted 1H‐Indenes
Authors: Zhou Qi , Li Shichao , Zhang Yan , Wang Jianbo 
Published: October 2017

AbstractA rhodium(II)‐ or copper(I)‐catalyzed formal intramolecular carbene insertion into vinylic C(sp2)−H bonds is reported herein. This method provides straightforward access to 1H‐indenes with high efficiency and excellent functional‐group compatibility. Mechanistically, the reaction is proposed to involve the following sequence: metal carbene formation, intramolecular nucleophilic addition of the double bond to the electron‐deficient carbene carbon atom, dearomatization, and finally a 1,5‐H shift.
Proton‐Coupled Reduction of the Catalytic [4Fe‐4S] Cluster in [FeFe]‐Hydrogenases
Authors: Senger Moritz , Laun Konstantin , Wittkamp Florian , Duan Jifu , Haumann Michael , Happe Thomas , Winkler Martin , Apfel Ulf‐Peter , Stripp Sven T. 
Published: October 2017

AbstractIn nature, [FeFe]‐hydrogenases catalyze the uptake and release of molecular hydrogen (H2) at a unique iron‐sulfur cofactor. The absence of an electrochemical overpotential in the H2 release reaction makes [FeFe]‐hydrogenases a prime example of efficient biocatalysis. However, the molecular details of hydrogen turnover are not yet fully understood. Herein, we characterize the initial one‐electron reduction of [FeFe]‐hydrogenases by infrared spectroscopy and electrochemistry and present evidence for proton‐coupled electron transport during the formation of the reduced state Hred′. Charge compensation stabilizes the excess electron at the [4Fe‐4S] cluster and maintains a conservative configuration of the diiron site. The role of Hred′ in hydrogen turnover and possible implications on the catalytic mechanism are discussed. We propose that regulation of the electronic properties in the periphery of metal cofactors is key to orchestrating multielectron processes.
Electromechanical instability in silicone‐ and acrylate‐based dielectric elastomers
Authors: Jiang Liang , Zhou Yanfen , Chen Shaojuan , Ma Jianwei , Betts Anthony , Jerrams Stephen 
Published: October 2017

ABSTRACTElectromechanical instability (EMI) is regarded as a significant factor in preventing dielectric elastomers (DEs) from achieving large voltage‐induced deformations. In this study, the strain‐stiffening effect was used to control the occurrence of EMI in DEs. The results show that the stretching ratio required to provide a feasible strain‐stiffening effect in silicone rubber (SR) was smaller than that needed for a commercial DE material, VHB 4910. The experimental data were compared with currently used models for the simulation of EMI in DEs. We found that EMI could be eliminated in the deformation of these elastomers when prestretching was used. Through the application of a prestretching ratio of above 2.0, EMI was suppressed in both the VHB 4910 and SR samples. The findings of this research are of great significance in the maximization of the electromechanical performance of DE materials. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 45733.
Synthesis and properties of phenyl carboxyl polydimethylsiloxane for fabrics treatment
Authors: Ji Chunda , Li Fengfu , Yun Zhi 
Published: October 2017

ABSTRACTA series of phenyl carboxyl polydimethylsiloxane (PCPDMS) with different relative molecular mass, phenyl and carboxyl content was prepared through condensation reaction and equilibrium polymerization. The effects of reaction conditions on the conversion were investigated, to determine the optimum reaction conditions. According to the thermal gravity analysis of PCPDMS with different relative molecular mass and phenyl content, it was found that the large relative molecular mass can improve the thermal stability of PCPDMS. The thermal stability of PCPDMS was significantly higher than carboxyl polydimethylsiloxane. Moreover, the PCPDMS emulsions were also prepared for the fabrics treatment. The emulsions can improve the wrinkle resistance, smoothness, elasticity, and other properties of the fabrics. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci.2018,135, 45866.
Positive‐tone photoresist consisting of a multifunctional acrylate resin that can be patterned after photo‐crosslinking
Authors: Sugita Hikaru , Miyashita Yuka , Suzuki Hiroyuki , Takasugi Shingo , Matsumura Nobuji , Yoshizawa Mitsuyo 
Published: October 2017

ABSTRACTA multifunctional acrylate resin having a tertiary ester structure is synthesized using a thiol‐acrylate Michael addition click reaction. By loading both a photo radical initiator and a photo acid generator into this resin, a positive‐tone photoresist, that can be patterned after photocrosslinking (PPaP), is formulated. After the thin film is irradiated with 365 nm light, radical crosslinking proceeds and a solvent resistant “frozen” film can be obtained. The frozen film works as a positive‐tone photoresist. When the frozen PPaP is irradiated with light containing a wavelength much shorter than 300 nm, the ester structure of the exposed region is decomposed by photo‐chemically generated acid and dissolved in an alkaline solution. Furthermore, a photochemical pattern transfer is achieved using the material. By performing the photo exposure on conventional photoresist patterns on the frozen PPaP underlayer, the photoresist patterns are successfully transferred to the underlayer. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 45871.
Interphase‐layer effect on deformation of silicone rubber filled with nanosilica particles
Authors: Adachi Tadaharu , Yamada Yuki , Ishii Yosuke 
Published: October 2017

ABSTRACTThe viscoelastic and statically tensile deformation properties of silicone rubber composites filled with nanosilica (300 nm in diameter) and microsilica particles (1.5 μm in diameter) were investigated on the basis of experimental results to clarify the interphase‐layer effect on these properties. The interphase layers formed around the nanoparticles without chemical coating were found to be glassy, even though the composites were in the rubbery state. The interphase layer thickness was determined to be approximately 20 nm using Guth and Gold's mixture law with the viscoelastic properties of the nanoparticle‐filled rubber in the rubbery state. The determined thickness of the interphase layer was confirmed by comparing the maximum strains at fracture for the nanoparticle‐filled rubber, which decreased for higher volume fraction of the nanoparticles. Therefore, the deformation properties were clarified to depend on the volume fraction of the apparent particles composed of the nanoparticles and interphase layers. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 45880.
Thermal, electrical, and dielectric properties of reduced graphene oxide–polyaniline nanotubes hybrid nanocomposites synthesized by in situ reduction and varying graphene oxide concentration
Authors: Devi Madhabi , Kumar Ashok 
Published: October 2017

ABSTRACTIn this study, reduced graphene oxide (RGO) has been introduced as conductive filler within polyaniline (PAni) nanotubes (PAniNTs) by in situ chemical reduction method to enhance the properties of PAniNTs. The effect of varied concentration of in situ reduced GO on the structural, thermal, electrical, and dielectric properties of RGO–PAniNTs nanocomposites have been investigated by high resolution transmission electron microscope, X‐ray diffraction, Fourier transform infrared, thermogravimetric analysis, I–V characteristics, and impedance analyzer. The enhanced thermal stability of the nanocomposites has been analyzed from the derivative thermogravimetric curves in terms of onset and rapid decomposition temperature. The transport mechanisms have been studied by fitting the nonlinear I–V characteristics to the Kaiser model. The dielectric relaxation phenomena have been investigated by permittivity and modulus formalisms. Characteristic relaxation frequency of RGO–PAniNTs nanocomposites shifts toward higher frequency with increasing RGO concentration indicating a distribution in conductivity relaxation. The distribution of relaxation time has been studied by fitting the imaginary modulus spectra of the nanocomposites to Bergman modified KWW function. The ac conductivity spectra are fitted to the Jonscher's power law equation and enhanced conductivity value of 1.26 × 10−3 S cm−1 is obtained for 40 wt % of RGO compared to 1.22 × 10−4 S cm−1 for PAniNTs. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 45883.
Tris(hydroxymethyl)aminomethane polyamide thin‐film‐composite antifouling reverse osmosis membrane
Authors: Chen Li‐Ye , Wu Li‐Ping , Zhang Hong‐Li , Gao Yu‐Bing , Gai Jing‐Gang 
Published: October 2017

ABSTRACTFor the applications of reverse osmosis (RO) process, membrane fouling caused by organic molecule adsorption is still a serious problem which significantly decreases membrane lifespan and increases operation costs. In this present article, we report the thin film composite (TFC) RO membrane functionalized with tris(hydroxymethyl)aminomethane (THAM) using one‐step method for improved antifouling property. The results of surface characterization indicated that THAM was successfully grafted onto the active layer of membrane by covalent linkage. Mult‐hydroxyl‐layer was generated and remained steadily on TFC membrane surface after modification. The contact angle decreased from 75.9 ± 3.0° to 46.9 ± 2.3°, which showed a distinct improvement of membrane surface hydrophilicity after modification. The grafted THAM improved water flux by 28.3%, while salt rejection was almost unchanged in membrane property tests. The modified membranes presented preferable antifouling property to foulants of bovine serum albumin, sodium alginate, and dodecyl trimethyl ammonium bromide than that of pristine membranes during dynamic fouling experiments. The method in this study provided an effective way to improve antifouling property of the polyamide thin‐film‐composite RO membrane. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 45891.
Environment‐friendly chemical recycling of aliphatic polyurethanes by hydrolysis in a CO2‐water system
Authors: Motokucho Suguru , Nakayama Yu , Morikawa Hiroshi , Nakatani Hisayuki 
Published: October 2017

ABSTRACTIn order to develop a chemical recycling system of polyurethanes (PUs), environment‐friendly hydrolysis of two types of aliphatic PUs was studied under pressured CO2 in water, in which the carbonic acid generated from CO2 acted as an acid catalyst. Two PUs, namely H‐PU or I‐PU, were synthesized starting from 1,4‐butanediol and 1,6‐hexamethylene diisocyanate or isophorone diisocyanate, respectively. The hydrolysis of PUs depended on the experimental conditions, such as the temperature and CO2 pressure. As a result, 98% of H‐PU and 91% of I‐PU were successfully hydrolyzed under the typical conditions of 190 °C for 24 h at 8.0 MPa CO2. The reaction mixtures afforded 1,4‐butanediol and diamines without the formation of any byproducts. Both of these raw materials generated from the originated PUs by selective hydrolytic cleavage of the urethane linkages, and they were easily isolated in high yields simply by evaporation of the water‐soluble components within the reaction mixture. By comparing the results of the two aliphatic PUs with those of an aromatic PU (M‐PU), the hydrolyzability was found to decrease in the order H‐PU, I‐PU, and M‐PU. The difference can be ascribed to the hydrophilicity of the aliphatic or aromatic groups connected to the urethane moieties at the terminals of PUs. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 45897.
Synthesis and properties of polyamides from 2,5‐furandicarboxylic acid
Authors: Cousin Thibault , Galy Jocelyne , Rousseau Alain , Dupuy Jérôme 
Published: October 2017

ABSTRACTThe aim of this study is to investigate the synthesis of 2,5‐furandicarboxylic acid (FDCA)‐based copolyamides. Indeed, FDCA monomer may be a potential bio‐based alternative to phthalic acids. A series of polyamides and copolyamides, PA 6‐I(x)/6‐F(y), are synthesized in a pilot scale reactor by melt polycondensation of salts based on FDCA, isophthalic acid (IPA), and 1,6‐hexamethylenediamine. The chemical structure and composition of the resulting copolymers are extensively characterized by NMR (1H, 13C, and 2D), MALDI‐TOF as well as size exclusion chromatography and solution viscosimetry. Their thermal properties are studied by differential scanning calorimetry and TGA and also by a molecular modeling technique. It is pointed out that, during the synthesis, FDCA‐rich polymers overcome a massive decarboxylation of FDCA, preventing the production of high molar mass polymers. It is also found that all polymers are amorphous and that the glass transition temperatures decrease as the amount of FDCA in the polymer increases. This is confirmed by the results from molecular dynamics. In addition, it is observed that the copolymers become more hygroscopic when the amount of FDCA in the copolyamides increases. However, the water uptake of PA 6‐I(x)/6‐F(y) with 90 > x > 50 is lower than those of PA6 and PA 66 polyamides. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 45901.
Understanding the Antibody Repertoire in Neuropsychiatric Systemic Lupus Erythematosus and Neuromyelitis Optica Spectrum Disorder
Authors: Mader Simone , Jeganathan Venkatesh , Arinuma Yoshiyuki , Fujieda Yuichiro , Dujmovic Irena , Drulovic Jelena , Shimizu Yuka , Sakuma Yuko , Stern Joel N. H. , Aranow Cynthia , Mackay Meggan , Yasuda Shinsuke , Atsumi Tatsuya , Hirohata Shunsei , Diamond Betty 
Published: October 2017

ObjectiveIgG anti‐DWEYS antibodies cross‐reactive with DNA and the N‐methyl‐d‐aspartate receptor subunits GluN2A and GluN2B are known to be associated with neuropsychiatric systemic lupus erythematosus (NPSLE). IgG anti‐DWEYS have not been investigated in demyelinating NPSLE or in another demyelinating disorder, neuromyelitis optica spectrum disorder (NMOSD), which is a disease also found mainly in young women and associated with aquaporin 4 (AQP‐4) or myelin oligodendrocyte glycoprotein (MOG) antibodies. This study was undertaken to investigate the frequency of all of these brain‐reactive antibodies in patients with NPSLE, those with demyelinating NPSLE, and those with NMOSD.MethodsSerum samples from patients with NPSLE (n = 108), patients with SLE without neuropsychiatric manifestations (n = 38), patients with NMOSD (n = 33), and healthy controls (n = 106) were assessed for the frequency of IgG anti‐brain antibodies as well as IgG antibodies to AQP‐4, MOG, GluN2A/GluN2B, and double‐stranded DNA (dsDNA).ResultsSera were positive for IgG anti–AQP‐4 antibodies in 27 (82%) of 33 patients with NMOSD and 3 (27%) of 11 patients with demyelinating NPSLE, whereas all sera from patients with non‐demyelinating NPSLE, patients with SLE, and healthy controls were negative for IgG anti–AQP‐4. IgG anti‐MOG were detected at high titers in 3 (50%) of 6 patients with NMOSD who were negative for IgG anti–AQP‐4, and at low titers in 2 (18%) of 11 patients with demyelinating NPSLE and 1 (1%) of 97 patients with non‐demyelinating NPSLE. IgG antibodies to dsDNA were present in 11 (33%) of 33 patients with NMOSD. Only 4 (12%) of 33 patients with NMOSD were positive for IgG anti‐DWEYS, compared to 11 (29%) of 38 patients with SLE and 59 (55%) of 108 patients with NPSLE. IgG anti‐DWEYS antibodies were present in 56 (58%) of 97 patients with non‐demyelinating NPSLE and 3 (27%) of 11 patients with demyelinating NPSLE. Serum IgG brain‐reactive antibodies were present at a similar frequency in patients with non‐demyelinating NPSLE (72 [75%] of 96), those with demyelinating NPSLE (9 [82%] of 11), and those with SLE (32 [84%] of 38), but were less frequent in patients with NMOSD (20 [61%] of 33).ConclusionPatients with demyelinating NPSLE should be tested for IgG antibodies to AQP‐4, MOG, and DWEYS. IgG anti–AQP‐4 can be considered diagnostic for NMOSD, whereas none of these antibodies appear to be diagnostic for demyelinating NPSLE. Moreover, IgG anti‐dsDNA are present in patients with NMOSD but are not cross‐reactive with IgG anti‐DWEYS, indicating that the antigenic stimulus and mechanisms of tissue damage are potentially different between demyelinating NPSLE and NMOSD.
Controllable Activation of Pd‐G3 Palladacycle Precatalyst in the Presence of Thiosugars: Rapid Access to 1‐Aminobiphenyl Thioglycoside Atropoisomers at Room Temperature
Authors: AL‐Shuaeeb Riyadh Ahmed Atto , Dejean Camille , Alami Mouâd , Messaoudi Samir 
Published: October 2017

AbstractA controllable method for the functionalization of XantPhos Pd‐G3 precatalyst with thiosugars and thiols has been established. Under mild and operationally simple reaction conditions through just mixing of precatalyst and thiosugars (α‐ or β‐mono‐, di‐ and poly‐thiosugar derivatives) in water at 25 °C for 20 min, a series of 1‐aminobiphenyl thioglycosides that are difficult to synthesize by classical methods has been synthesized in very high yields.
L1‐Gain Analysis and Control for Switched Positive Systems with Dwell Time Constraint
Authors: Shen Jian , Wang Weiqun 
Published: October 2017

AbstractThis paper studies the problems of L1‐gain analysis and control for switched positive systems with dwell time constraint. The state‐dependent switching satisfies a minimal dwell time constraint to avoid possible arbitrary fast switching. By constructing multiple linear co‐positive Lyapunov functions, sufficient conditions of stability and L1‐gain property are derived under the proposed switching strategy. Then, an effective state feedback controller is designed to ensure the positivity and L1‐gain property of the closed‐loop system. Finally, a simulation example is given to illustrate the effectiveness of the proposed method.