bluuebunny/crossref_metadata_2025_split huggingface dataset:
Improvement of actuation performance of dielectric elastomers by barium titanate and carbon black fillers
Authors: Poikelispää Minna , Shakun Alexandra , Das Amit , Vuorinen Jyrki 
Published: July 2016

ABSTRACTDielectric elastomers are promising materials for actuators resembling human muscle. Among elastomers, acrylic rubbers (ACM) have shown good actuation performance but its use is limited by the high operating voltages required. The present work demonstrates that simultaneous incorporation of nanostructured carbon black and dielectric fillers offers an increase in a dielectric permittivity and a suitable modulus of the elastomers matrix, enabling an improved electro‐mechanical actuation performance at low voltages. By the use of reinforcing carbon black and barium titanate in an acrylic elastomer matrix a sixfold increase in the dielectric permittivity was realized. A fine tuning of the actuation stress and, consequently, actuation strain can be done by a judicial selection of the different filler concentrations in the soft rubber matrix. Finally, a synergistic effect of the fillers was observed in the improved actuation performance of the developed materials. This work may pave the way to design dielectric elastomers for actuator fabrication. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 44116.
Enhanced stiffness of silk‐like fibers by loop formation in the corona leads to stronger gels
Authors: Rombouts Wolf H. , Domeradzka Natalia E. , Werten Marc W.T. , Leermakers Frans A.M. , de Vries Renko J. , de Wolf Frits A. , van der Gucht Jasper 
Published: July 2016

AbstractWe study the self‐assembly of protein polymers consisting of a silk‐like block flanked by two hydrophilic blocks, with a cysteine residue attached to the C‐terminal end. The silk blocks self‐assemble to form fibers while the hydrophilic blocks form a stabilizing corona. Entanglement of the fibers leads to the formation of hydrogels. Under oxidizing conditions the cysteine residues form disulfide bridges, effectively connecting two corona chains at their ends to form a loop. We find that this leads to a significant increase in the elastic modulus of the gels. Using atomic force microscopy, we show that this stiffening is due to an increase of the persistence length of the fibers. Self‐consistent‐field calculations indicate a slight decrease of the lateral pressure in the corona upon loop formation. We argue that this small decrease in the repulsive interactions affects the stacking of the silk‐like blocks in the core, resulting in a more rigid fiber.
Intramolecular backbone···backbone hydrogen bonds in polypeptide conformations. The other way around: ɛ‐turn
Authors: Toniolo Claudio , Crisma Marco , Formaggio Fernando , Alemán Carlos , Ramakrishnan Chandrasekharan , Kalmankar Neha , Balaram Padmanabhan 
Published: July 2016

AbstractIn this study, we performed a detailed literature survey of the ɛ‐turn in peptides and proteins. This three‐dimensional structural feature is characterized by an eleven‐membered pseudo‐cycle closed by an intramolecular backbone…backbone H‐bond. Interestingly, in this motif the direction of the N‐H…O = C H‐bond runs opposite to that of the much more popular and extensively investigated α‐, β‐, and γ‐turns. We did not authenticate unequivocally the ɛ‐turn main‐chain reversal topology in any linear short peptide. However, it is frequently observed in small cyclic peptides formed by four, five, and six amino acid residues with stringent geometric requirements. Rather surprisingly, ɛ‐turns do occur in proteins, although to a relatively moderate extent, as an isolated feature or in the turn segment of hairpin motifs based on two antiparallel, pleated β‐strands. Moreover, the ɛ‐turn may also host not only the seven‐membered, intramolecularly H‐bonded, pseudo‐cycle termed γ‐turn, either of the classic or inverse type, but also one (or even two) cis peptide bond(s) or a β‐bulge conformation. Based on their ϕ, ψ backbone torsion angles, we were able to classify the protein ɛ‐turns in six different families. Conformational energy computations using the DFT methodology were also performed on the ɛ‐turns adopted by the amino acid triplet ‐Gly‐Gly‐Gly‐ (Gly is the most commonly found residue at each of the three positions in our analysis of proteins). Again, in this computational study, six families of turns were identified, but only some of them resemble rather closely those extracted from our investigation on proteins.
Crystal structures of peptidic catalysts of the H‐dPro‐Pro‐Xaa type
Authors: Grünenfelder Claudio E. , Kisunzu Jessica K. , Trapp Nils , Kastl Robert , Wennemers Helma 
Published: July 2016

AbstractCrystal structures of catalytically active tripeptides of the general type H‐dPro‐Pro‐Xaa and related N‐acetylated analogs were compared. The influence of acylation at the N‐terminus, the nature of the C‐terminal residue, coordinating groups, and intramolecular hydrogen bonds on the conformation of the tripeptides was examined. Regardless of the presence or absence of stabilizing intramolecular H‐bonds or n → π* interactions, all of the analyzed peptides share a β‐turn‐like conformation, which highlights the structural rigidity of the dPro‐Pro motif and its value for conformational preorganization. The C‐terminal residues and coordinating moieties were found to affect the turn‐conformation, which suggests that H‐dPro‐Pro‐Xaa type peptides are sufficiently flexible to adopt distinctly different but related conformations.
Feasibility of hybrid off pump artery bypass grafting and transaortic transcatheter aortic valve implantation: A case series
Authors: Manoly Imthiaz , Hasan Ragheb , Brazier Andrew , Farooq Vasim , Thompson Thomas , Karunaratne Devinda , Naylor Heather , Fraser Douglas 
Published: July 2016

IntroductionPatients with complex coronary artery disease and severe aortic stenosis unsuitable for conventional cardiac surgery pose a significant treatment challenge. This is especially difficult for patients where percutaneous revascularization is technically very challenging and/or would not offer as complete revascularisation compared to surgical revascularisation. In addition, patients who are unsuitable for transfemoral transcatheter aortic valve implantation (TAVI) pose an additional technical challenge, particularly with dual antiplatelet therapy (DAPT) following percutaneous coronary intervention (PCI). As a potential solution we describe the first case series of hybrid off‐pump coronary artery bypass grafting (CABG) combined with transaortic TAVI.Methods and resultsOver a ten‐month‐period, four patients underwent hybrid off‐pump CABG combined with transaortic TAVI. A full sternotomy allowed off‐pump arterial and vein graft anastomosis to significantly stenosed coronaries. The first three patients had severe aorto‐iliac disease precluding femoral access; the fourth patient was deemed unsuitable for PCI. Transaortic TAVI using Edwards Sapien 3 valves were performed without complication in all four patients.ConclusionThe hybrid off‐pump CABG and transaortic TAVI procedure allows for more complete coronary revascularization, negates the need for DAPT, and minimizes treatment delay of a TAVI procedure, particularly in patients unsuitable for transfemoral access. We propose this as an important treatment option for the heart team to consider. © 2016 Wiley Periodicals, Inc.
Saphenous vein bypass graft intervention and embolic protection devices: Time for reassessment (and revision of percutaneous coronary intervention guidelines)
Authors: Safian Robert D. 
Published: July 2016

Key Points

Professional societies recommend embolic protection devices (EPDs) during percutaneous intervention of saphenous vein bypass grafts (SVGs; class I, level of evidence B).
Practice patterns indicate that 21% of SVG interventions are performed with EPDs. Despite a single randomized trial that demonstrated efficacy for EPDs, other studies suggest that the benefits of EPDs are controversial.
Consideration should be given toward performing a contemporary EPD trial to incorporate new technologies and pharmacotherapies; in the meantime, guideline recommendations for use of EPDs should be downgraded.
Is there a Specific Ecological Niche for Electroactive Microorganisms?
Authors: Koch Christin , Harnisch Falk 
Published: July 2016

AbstractThe core of primary microbial electrochemical technologies (METs) is the ability of the electroactive microorganisms to interact with electrodes via extracellular electron transfer (EET), allowing wiring of current flow and microbial metabolism. Geobacter sulfurreducens and Shewanella oneidensis are the model organisms for understanding and engineering EET. Many other microorganisms are reported being electroactive but are often sparsely characterized. Based on a literature survey 94 species are ascribed as electroactive. Their apparent diversity raises questions on the natural importance and distribution of the EET capacity, that is, of the ecological niche of microbial electroactivity. To identify this potential niche the environmental preferences and natural habitat characteristics of all electroactive species were combined with their metabolic, growth and EET characteristics and an extensive meta‐analysis performed. The results indicate that there is not a single ecological niche for electroactive microorganisms. Significantly more electroactive species presumably exist in nature as well as already existing strain collections but due to current cultivation techniques their EET potential is not leveraged. Thus, in the light of specific traits required for industrial application, microbial resource mining based on ecological knowledge bears a great potential for broadening the foundation of microbial electrochemistry as well as for future developments of primary METs.
Competitive Excimer Formation and Energy Transfer in Zr‐Based Heterolinker Metal–Organic Frameworks
Authors: Gutiérrez Mario , Sánchez Félix , Douhal Abderrazzak 
Published: July 2016

AbstractThe spectroscopy and dynamics of a series of Zr‐based MOFs in dichloromethane suspension are reported. These Zr‐NADC MOFs were constructed by using different mixtures of 2,6‐naphthalenedicarboxylate (NDC) and 4‐amino‐2,6‐naphthalenedicarboxylate (NADC) as organic linkers. The fraction of NADC relative to NDC in these heterolinker MOFs ranges from 2 to 35 %. The results indicate two competitive photoprocesses: NDC excimer formation and an energy transfer (ET) from excited NDC linkers to NADC linkers. Increasing the fraction of NADC linkers in the Zr‐NADC nanostructure decreases the mean time constant of NDC excimer formation, while the NADC emission intensity experiences a drop at the highest fraction of this linker in the MOF. The first observation is explained by an increase in the energy‐transfer probability between the two linkers, and the second by emission quenching in the NADC linkers due to ultrafast charge transfer assisted by the amino group. Femtosecond time‐resolved emission studies showed that the ET process (recorded as decaying and rising components) from excited NDC to NADC takes place in 1.2 ps. Direct excitation of the NADC linkers (at 410 nm) shows a decaying, but not rising, component of 250–480 fs, which could reflect the formation of a nonemissive charge‐separation state. The results show that by using MOFs having heterolinkers it is possible to trigger and tune excimer formation and ET processes.
Light‐ and Solvent‐Controlled Self‐Assembly Behavior of Spiropyran–Polyoxometalate–Alkyl Hybrid Molecules
Authors: Chu Yang , Saad Ali , Yin Panchao , Wu Jiayingzi , Oms Olivier , Dolbecq Anne , Mialane Pierre , Liu Tianbo 
Published: July 2016

AbstractA molecular photochromic spiropyran–polyoxometalate–alkyl organic–inorganic hybrid has been synthesized and fully characterized. The reversible switching of the hydrophobic spiropyran fragment to the hydrophilic merocyanine one can be easily achieved under light irradiation at different wavelengths. This switch changes the amphiphilic feature of the hybrid, leading to a light‐controlled self‐assembly behavior in solution. It has been shown that the hybrid can reversibly self‐assemble into vesicles in polar solvents and irreversibly into reverse vesicles in non‐polar solvents. The sizes of the vesicles and the reverse vesicles are both tunable by the polarity of the solvent, with the hydrophobic interactions being the main driving force.
Design of Assembled Systems Based on Conjugated Polyphenylene Derivatives and Carbon Nanohorns
Authors: Iglesias Daniel , Guerra Javier , Gómez M. Victoria , Rodríguez Antonio M. , Prieto Pilar , Vázquez Ester , Herrero M. Antonia 
Published: July 2016

AbstractPromising materials have been designed and fully characterised by an effective interaction between versatile platforms such as carbon nanohorns (CNHs) and conjugated molecules based on thiophene derivatives. Easy and non‐aggressive methods have been described for the synthesis and purification of the final systems. Oligothiophenephenylvinylene (OTP) systems with different geometries and electron density are coupled to the CNHs. A wide range of characterization techniques have been used to confirm the effective interaction between the donor (OTP) and the acceptor (CNH) systems. These hybrid materials show potential for integration into solar cell devices. Importantly, surface‐enhanced Raman spectroscopy (SERS) effects are observed without the presence of any metal surface in the system. Theoretical calculations have been performed to study the optimised geometries of the noncovalent interaction between the surface and the organic molecule. The calculations allow information on the monoelectronic energies of HOMO–LUMO orbitals and band gap of different donor systems to be extracted.
Azulenylcarbenes: Rearrangements on the C11H8 Potential Energy Surface
Authors: Henkel Stefan , Pollok Corina H. , Schleif Tim , Sander Wolfram 
Published: July 2016

AbstractFour isomeric azulenylcarbenes were synthesized in argon matrices by photolysis of the corresponding diazo precursors, and the photochemistry of these carbenes was studied. The carbenes and their rearranged products were characterized by IR, UV/Vis, and EPR spectroscopy, and the experimental data were compared to results from DFT calculations. While 2‐, 5‐ and 6‐azulenylcarbene show triplet ground states, 1‐azulenylcarbene exhibits a singlet ground state, in accord with theoretical predictions. The rearrangements of the azulenylcarbenes give access to a number of unusual C11H8 isomers, such as other carbenes and strained allenes.
Ionic Liquids Can Permanently Modify Porous Silicon Surface Chemistry
Authors: Trivedi Shruti , Coombs Sidney G. , Wagle Durgesh V. , Bhawawet Nakara , Baker Gary A. , Bright Frank V. 
Published: July 2016

AbstractTo develop ionic liquid/porous silicon (IL/pSi) microarrays we have contact pin‐printed 20 hydrophobic and hydrophilic ionic liquids onto as‐prepared, hydrogen‐passivated porous silicon (ap‐pSi) and then determined the individual IL spot size, shape and associated pSi surface chemistry. The results reveal that the hydrophobic ionic liquids oxidize the ap‐pSi slightly. In contrast, the hydrophilic ionic liquids lead to heavily oxidized pSi (i.e., ox‐pSi). The strong oxidation arises from residual water within the hydrophilic ILs that is delivered from these ILs into the ap‐pSi matrix causing oxidation. This phenomenon is less of an issue in the hydrophobic ILs because their water solubility is substantially lower.
Electrons Mediate the Gas‐Phase Oxidation of Formic Acid with Ozone
Authors: van der Linde Christian , Tang Wai‐Kit , Siu Chi‐Kit , Beyer Martin K. 
Published: July 2016

AbstractGas‐phase reactions of CO3.− with formic acid are studied using Fourier transform ion cyclotron resonance (FT‐ICR) mass spectrometry. Signal loss indicates the release of a free electron, with the formation of neutral reaction products. This is corroborated by adding traces of SF6 to the reaction gas, which scavenges 38 % of the electrons. Quantum chemical calculations of the reaction potential energy surface provide a reaction path for the formation of neutral carbon dioxide and water as the thermochemically favored products. From the literature, it is known that free electrons in the troposphere attach to O2, which in turn transfer the electron to O3. O3.− reacts with CO2 to form CO3.−. The reaction reported here formally closes the catalytic cycle for the oxidation of formic acid with ozone, catalyzed by free electrons.
Direct Synthesis of α‐Allenols from TMS‐Protected Alkynes and Aldehydes Mediated by Tetrabutylammonium Fluoride
Authors: Huang Xiaojun , Bugarin Alejandro 
Published: July 2016

AbstractA unique chemoselective synthesis of α‐allenic alcohols is presented. Tetrabutylammonium fluoride (TBAF) mediated this transformation under mild reaction conditions. A range of functional groups is well‐tolerated in this reaction, while affording adducts in moderate to excellent yields (48–96 %, average 76 %). Mechanistic studies, including the use of tetrabutylammonium hydroxide (TBAH), revealed that the hydroxide ion can be the responsible for the observed rearrangement.
A Novel Ratiometric Oxygen Sensor Based On a Sextuple Hydrogen‐Bonding Self‐Assembly Molecular Heterodimer
Authors: Zeng Hui , Zhang Cheng , Huang Yan , Lu Zhiyun 
Published: July 2016

AbstractA novel sextuple hydrogen‐bonding (HB) self‐assembly molecular heterodimer bearing an iridium complex as the indicator dye and two carbazoles as the reference dye, namely 6HB‐Irbt‐Cz, was synthesized, and its molecular structure was confirmed by 1H NMR, 13CNMR, TOF‐MS and 2D NMR. Because of the inefficient energy transfer process between the carbazole and iridium complex units, 6HB‐Irbt‐Cz exhibits distinct ?uorescence/phosphorescence dual emission in neat film state. More importantly, the neat film sample of 6HB‐Irbt‐Cz could display linear ratiometric optical response toward oxygen in the full oxygen concentration range from 0 to 100 vol%, together with good stability, reversibility and rapid response‐recovery times. Note that this represents the first discovery of neat‐film‐based oxygen sensor capable of showing strictly linear ratiometric Stern‐Volmer behavior in the oxygen concentration of 0–100 vol%.
Efficient Synthesis of Isoquinolines by AgNO3‐Catalyzed Sequential Imination‐Annulation of 2‐Alkynyl Aldehydes with Ammonium Bicarbonate
Authors: Zhao Yunhui , Luo Mingjian , Li Yubo , Liu Xiong , Tang Zilong , Deng Keqin , Zhao Gang 
Published: July 2016

AbstractAn operationally simple approach for the tandem synthesis of isoquinolines by the reaction of o‐alkynylaldehydes with ammonium bicarbonate via Ag‐catalyzed 6‐endo‐dig ring closure is described. The reaction conditions and the scope of the reaction are examined, and a variety of substituted isoquinolines are prepared in moderate to excellent yields.
Validation study of HPV DNA detection from stained FNA smears by polymerase chain reaction: Improving the diagnostic workup of patients with a tumor on the neck
Authors: Channir Hani Ibrahim , Grønhøj Larsen Christian , Ahlborn Lise Barlebo , van Overeem Hansen Thomas , Gerds Thomas Alexander , Charabi Birgitte Wittenborg , Vainer Ben , von Buchwald Christian , Lajer Christel Bræmer , Kiss Katalin 
Published: July 2016

BACKGROUNDHuman papillomavirus (HPV)–related oropharyngeal squamous cell carcinoma (OPSCC) often presents with cystic cervical metastasis and a small primary tumor localized in the palatine tonsils or base of the tongue, which is diagnostically challenging. Testing for HPV DNA in fine‐needle aspiration (FNA) smears from metastases may facilitate a targeted diagnostic workup for identifying the primary tumor. This study was designed to assess the ability to detect HPV DNA in FNA smears with polymerase chain reaction (PCR).METHODSMay‐Grünvald‐Giemsa (MGG)–stained FNA smears from metastases and corresponding surgical specimens were collected from 71 patients with known HPV‐positive OPSCC, 12 patients with oral squamous cell carcinoma (OSCC), 20 patients with branchial cleft cysts, and 20 patients with Warthin tumors. Thirty‐eight patients with OPSCC and 7 patients with OSCC had FNA smears available from metastases and also surgical specimens from the primary tumor and the metastases. The scraped cell material from FNA smears and corresponding surgical specimens were analyzed for HPV DNA by PCR. p16 immunohistochemistry was performed on surgical specimens from the carcinomas.RESULTSHPV DNA was detected in 68 of the 71 FNA smears from OPSCC metastases. All corresponding surgical specimens from primary tumors (n = 71) and metastases (n = 38) were p16‐ and HPV DNA–positive. All the surgical specimens and corresponding FNA smears from OSCCs, Warthin tumors, and branchial cleft cysts were HPV DNA–negative. The sensitivity and specificity were 94.7% and 100%, respectively.CONCLUSIONSThe detection of HPV DNA in MGG‐stained FNA smears by PCR is a valid method that could be implemented in routine clinical practice. Cancer Cytopathol 2016;124:820‐7. © 2016 American Cancer Society.
Antisolvent crystallization of aqueous ammonium dihydrogen phosphate solutions by addition of acetone at different rates
Authors: Sangwal Keshra , Mielniczek‐Brzóska Ewa 
Published: July 2016

Results of an investigation of in situ measurements of laser‐beam intensity Is and Im transmitted through aqueous ammonium dihydrogen phosphate (ADP) solutions saturated at 30 °C and water, respectively, and temperature Ts of solution and Tm of water during feeding of antisolvent acetone at different rates RA, using an indigenously designed experimental setup, are presented and discussed. It was found that: (1) for the measurement of MSZW, defined as the maximum volume fraction of acetone content Δxmax in the solution, obtained from temperature measurements are more reliable than transmitted laser‐beam intensity measurements for solutions, (2) two minima ΔTmin1 and ΔTmin2 associated with endothermic reactions, separated by a maximum ΔTmax due to exothermic reactions appear in the plots of temperature difference ΔT = Ts−Tm against acetone feeding time t, and (3) in the ΔT(t) plots there are time intervals Δt of constant rates RT of increase in ΔT of aqueous ADP solutions, and these values of RT increase linearly with acetone feeding time rate RA. The experimental data on the observed dependence of MSZW on antisolvent feeding rate RA, the appearance of minima ΔTmin1 and ΔTmin2 and maximum ΔTmax and their dependence on RA, and the relationship between RT and RA are discussed from consideration of processes of nucleation and growth of crystallites.
Red Mud and Li‐Ion Batteries: A Magnetic Connection
Authors: Suryawanshi Anil , Aravindan Vanchiappan , Madhavi Srinivasan , Ogale Satishchandra 
Published: July 2016

AbstractExceptional Li‐ion battery performance is presented with the oxide component of the anode was extracted from red mud by simple magnetic separation and applied directly without any further processing. The extracted material has γ‐Fe2O3 as the major phase with inter‐dispersed phases of Ti, Al, and Si oxides. In a half‐cell assembly, the phase displayed a reversible capacity (∼697 mA h g−1) with excellent stability upon cycling. Interestingly, the stability is rendered by the multiphase constitution of the material with the presence of other electrochemically inactive metal oxides, such as Al2O3, SiO2, and Fe2TiO4, which could accommodate the strain and facilitate release during the charge–discharge processes in the electrochemically active maghemite component. We fabricated the full‐cell assembly with eco‐friendly cathode LiMn2O4 by adjusting the mass loading. Prior to full‐cell assembly, an electrochemical pre‐lithiation was enforced to overcome the irreversible capacity loss obtained from the anode. The full‐cell delivered a capacity of ∼100 mA h g−1 (based on cathode loading) with capacity retention of ∼61 % after 2000 cycles under ambient conditions.