bluuebunny/crossref_metadata_2025_split huggingface dataset:
Biophysical characterization of quaternary pyridinium functionalized polynorbornenes for DNA complexation and their cellular interactions
Authors: Guler Gokce Zeliha , Zuhal Birol Semra , Eren Tarık , Ercelen Ceylan Sebnem 
Published: November 2016

AbstractCationic polymers with hydrophobic side chains have gained great interest as DNA carriers since they form a compact complex with negatively charged DNA phosphate groups and interact with the cell membrane. Amphiphilic polyoxanorbornenes with different quaternary alkyl pyridinium side chains with ethyl‐p(OPy2) and hexyl units‐p(OPy6) bearing 10 kDa MWT were synthesized by living Ring‐Opening Metathesis Polymerization method.The physicochemical characteristics: critical micellar concentration, size distribution, surface charge, and condensation of polymer/DNA complex were investigated. Morphology of complexes was monitored by Atomic force microscopy. Cytotoxicity and interaction of these complexes with model lipid vesicles mimicking the cell membrane were examined. These polymers were enabled to form small sized complexes of DNA, which interact with model membrane vesicles. It was found that the nature of hydrophobicity of the homopolymers significantly impacts rates of DNA complexation and the surface charge of the resulting complexes. These results highlight the prospect of the further examinations of these polymers as gene carriers.
Using yeast to determine the functional consequences of mutations in the human p53 tumor suppressor gene: An introductory course‐based undergraduate research experience in molecular and cell biology
Authors: Hekmat‐Scafe Daria S. , Brownell Sara E. , Seawell Patricia Chandler , Malladi Shyamala , Imam Jamie F. Conklin , Singla Veena , Bradon Nicole , Cyert Martha S. , Stearns Tim 
Published: November 2016

AbstractThe opportunity to engage in scientific research is an important, but often neglected, component of undergraduate training in biology. We describe the curriculum for an innovative, course‐based undergraduate research experience (CURE) appropriate for a large, introductory cell and molecular biology laboratory class that leverages students′ high level of interest in cancer. The course is highly collaborative and emphasizes the analysis and interpretation of original scientific data. During the course, students work in teams to characterize a collection of mutations in the human p53 tumor suppressor gene via expression and analysis in yeast. Initially, student pairs use both qualitative and quantitative assays to assess the ability of their p53 mutant to activate expression of reporter genes, and they localize their mutation within the p53 structure. Through facilitated discussion, students suggest possible molecular explanations for the transactivation defects displayed by their p53 mutants and propose experiments to test these hypotheses that they execute during the second part of the course. They use a western blot to determine whether mutant p53 levels are reduced, a DNA‐binding assay to test whether recognition of any of three p53 target sequences is compromised, and fluorescence microscopy to assay nuclear localization. Students studying the same p53 mutant periodically convene to discuss and interpret their combined data. The course culminates in a poster session during which students present their findings to peers, instructors, and the greater biosciences community. Based on our experience, we provide recommendations for the development of similar large introductory lab courses. © 2016 by The International Union of Biochemistry and Molecular Biology, 45(2):161–178, 2017.
The Low‐Temperature Oxidation of Propane by using H2O2 and Fe/ZSM‐5 Catalysts: Insights into the Active Site and Enhancement of Catalytic Turnover Frequencies
Authors: Peneau Virginie , Armstrong Robert D. , Shaw Greg , Xu Jun , Jenkins Robert L. , Morgan David J. , Dimitratos Nikolaos , Taylor Stuart H. , Zanthoff Horst W. , Peitz Stefan , Stochniol Guido , He Qian , Kiely Christopher J. , Hutchings Graham J. 
Published: November 2016

AbstractFe‐containing ZSM‐5 catalysts are reported to be efficient catalysts for the partial oxidation of propane to oxygenated products at reaction temperatures as low as 50 °C in an aqueous phase reaction when using the green oxidant H2O2. It was previously proposed that extra framework Fe species at the exchange sites of the zeolite are responsible for activation of both the alkane and hydrogen peroxide. Through a systematic study of the influence of framework topology and exchange properties, it is now shown that this high catalytic activity is specific to the MFI‐type Brønsted acidic zeolite ZSM‐5. Furthermore, through a simple aqueous acid washing treatment, leaching of approximately 77 % of iron present within a Fe/ZSM‐5 catalyst only caused the relative propane conversion to decrease by 17 %; implying that most of the initially loaded Fe does not actually contribute to the catalytic activity. This small change in conversion after ‘excess’ Fe removal, amounts to a three‐fold increase in turnover frequency (TOF) (Fe) from 66 h−1 to 232 h−1 compared with the parent Fe/ZSM‐5 catalyst. By comparing these samples, it is shown by NH3 temperature‐programmed desorption, 27Al magic angle spinning NMR spectroscopy, X‐ray photoelectron spectroscopy and TEM analysis that surface iron oxide species are effectively spectators in the oxidation of propane with H2O2. This provides further insight as to the location and true nature of the catalytically active Fe species.
Characterization of Carboxylic Acid Reductases as Enzymes in the Toolbox for Synthetic Chemistry
Authors: Finnigan William , Thomas Adam , Cromar Holly , Gough Ben , Snajdrova Radka , Adams Joseph P. , Littlechild Jennifer A. , Harmer Nicholas J. 
Published: November 2016

AbstractCarboxylic acid reductase enzymes (CARs) meet the demand in synthetic chemistry for a green and regiospecific route to aldehydes from their respective carboxylic acids. However, relatively few of these enzymes have been characterized. A sequence alignment with members of the ANL (Acyl‐CoA synthetase/ NRPS adenylation domain/Luciferase) superfamily of enzymes shed light on CAR functional dynamics. Four unstudied enzymes were selected by using a phylogenetic analysis of known and hypothetical CARs, and for the first time, a thorough biochemical characterization was performed. Kinetic analysis of these enzymes with various substrates shows that they have a broad but similar substrate specificity. Electron‐rich acids are favored, which suggests that the first step in the proposed reaction mechanism, attack by the carboxylate on the α‐phosphate of adenosine triphosphate (ATP), is the step that determines the substrate specificity and reaction kinetics. The effects of pH and temperature provide a clear operational window for the use of these CARs, whereas an investigation of product inhibition by NADP+, adenosine monophosphate, and pyrophosphate indicates that the binding of substrates at the adenylation domain is ordered with ATP binding first. This study consolidates CARs as important and exciting enzymes in the toolbox for sustainable chemistry and provides specifications for their use as a biocatalyst.
A Hemilabile and Cooperative N‐Donor‐Functionalized 1,2,3‐Triazol‐5‐Ylidene Ligand for Alkyne Hydrothiolation Reactions
Authors: Strydom Ian , Guisado‐Barrios Gregorio , Fernández Israel , Liles David C. , Peris Eduardo , Bezuidenhout Daniela I. 
Published: November 2016

AbstractA series of novel cationic and neutral Rh complexes with an N‐donor‐functionalized 1,2,3‐triazol‐5‐ylidene (TRZ) ligand (in which the pendant N donor is NHBoc, NH2, or NMe2) is described. The catalytic activity of these complexes was evaluated in the hydrothiolation of alkynes. Among the catalysts, a neutral dicarbonyl complex featuring the tethered‐NBoc amido‐TRZ ligand proved very selective for alkyne hydrothiolation with an aryl thiol. Remarkably, the reaction could be carried out in the absence of pyridine or base additive. In addition, during the reaction, no evidence for oxidative addition of the thiol S−H bond was observed, strongly suggesting a reaction pathway in which a bifunctional ligand is involved. Experimental and theoretical mechanistic investigations suggest a ligand‐assisted deprotonation of thiol, hemilabile dissociation of amine from the metal, and thiolate coordination, which is indicative of a different reaction mechanism to those previously reported for related alkyne hydrothiolation reactions.
From Additivity to Cooperativity in Chemistry: Can Cooperativity Be Measured?
Authors: Tebben Ludger , Mück‐Lichtenfeld Christian , Fernández Gustavo , Grimme Stefan , Studer Armido 
Published: November 2016

AbstractCooperative effects can be observed in various research areas in chemistry; cooperative catalysis is well‐established, the assembly of compounds on surfaces can be steered by cooperative effects, and supramolecular polymerization can proceed in a cooperative manner. In biological systems, cooperativity is observed in protein–protein, protein–lipid and protein–molecule interactions. Synergistic effects are relevant in frustrated Lewis pairs, organic multispin systems, multimetallic clusters and also in nanoparticles. However, a general approach to determine cooperativity in the different chemical systems is currently not known. In the present concept paper it is suggested that, at least for simpler systems that can be described at the molecular level, cooperativity can be defined based on energy considerations. For systems in which no chemical transformation occurs, determination of interaction energies of the whole system with respect to the interaction energies between all individual component pairs (subsystems) will allow determination of cooperativity. For systems comprising of chemical transformations, cooperativity can be evaluated by determining the activation energy of the synergistic system and by comparing this with activation energies of the corresponding subsystems that lack an activating moiety. For more complex systems, cooperativity is generally determined at a qualitative level.
Bismuth Perfluoroalkylphosphinates: New Catalysts for Application in Organic Syntheses
Authors: Solyntjes Sven , Neumann Beate , Stammler Hans‐Georg , Ignat'ev Nikolai , Hoge Berthold 
Published: November 2016

AbstractCommercially available BiPh3 was treated with perfluoroalkylphosphinic acids [for example, (C2F5)2P(O)OH] to generate novel, highly Lewis acidic bismuth(III) perfluoroalkylphosphinates of the type PhxBi[RF2PO2]3−x (x=0, 1, 2) (RF=‐C2F5, ‐C4F9). The first bismuth(V) perfluoroalkylphosphinate, Ph3Bi[(C2F5)2PO2]2, was synthesized from Ph3BiCl2 and Ag[(C2F5)2PO2]. Examples for the successful application of the catalytically active bismuth(III) and bismuth(V) phosphinates in carbon–carbon bond forming reactions, such as Friedel–Crafts acylation and alkylation, Diels–Alder, Strecker and Mannich reaction, are presented.
Tandem Aryne‐Capture/Sigmatropic Rearrangement as a Metal‐Free Entry to Functionalized N‐Aryl Pyrrolidines
Authors: Moss Sam G. , Pocock Ian A. , Sweeney Joseph B. 
Published: November 2016

AbstractWe report a new method for the synthesis of novel N‐aryl proline analogues. By reacting an aryne precursor with N‐(2‐malonyl) tetrahydropyridines in the presence of tetrabutylammonium fluoride (TBAF), a tandem aryne‐capture/anion isomerisation/[2,3]‐sigmatropic rearrangement is induced, leading to good yields of 3‐substituted N‐aryl‐2‐acylpyrrolidines. These products are known subunits of biological probes, sensors and drug‐like fragments, and are not easily accessed directly by other methods. The reaction is also notable as the first [2,3]‐rearrangement of cyclic ammonium ylides at room temperature.
Servir les clients avec le sourire: Source d'épuisement ou de performance chez les employés de centres d'appels?
Authors: Picard Karel , Cossette Michel , Morin Denis 
Published: November 2016

AbstractThis study examines the relationships between emotional labour (surface acting, deep acting, and natural expression of positive emotions) and emotional exhaustion and service performance among 215 call centre employees. Of the hypotheses concerning the relation between the three emotional regulation strategies to emotional exhaustion and to service performance, only natural expression of positive emotion is significantly related to both consequences. Results also suggest that neuroticism moderates the link between deep acting and emotional exhaustion: employees with low levels of neuroticism seem more emotionally exhausted when they use deep acting. Copyright © 2016 ASAC. Published by John Wiley & Sons, Ltd.
Writing out praise: Air Canada employees and the 1968 CEO change
Authors: Hartt Christopher M. 
Published: November 2016

AbstractIn 1968, the Air Canada CEO was an individual from outside the airline industry, when previously all CEOs had been former airline pilots for the organization. In investigating why, the union writings of Air Canada, a large Crown corporation, make no reference to this 1968 CEO change. I examine how the values, beliefs, and ideas of employees affect the development of an organization's written histories. I apply actor network theory, sensemaking, critical sensemaking, and theories of “writing out” to expose and develop the concept of the noncorporeal actant as a critical influence within a network and in the writing of histories. Copyright © 2016 ASAC. Published by John Wiley & Sons, Ltd.
Myxochelin‐Inspired 5‐Lipoxygenase Inhibitors: Synthesis and Biological Evaluation
Authors: Schieferdecker Sebastian , König Stefanie , Pace Simona , Werz Oliver , Nett Markus 
Published: November 2016

AbstractA total of 48 analogues of the natural product myxochelin A were prepared and evaluated for their inhibitory effects on human 5‐lipoxygenase in both cell‐free and cell‐based assays. Structure–activity relationship analysis revealed that the secondary alcohol function and only chiral center of myxochelin A is not required for biological activity. By expanding the diaminoalkane linker of the two aromatic residues it was possible to generate a myxochelin derivative with superior activity against 5‐lipoxygenase in intact cells.
A Viologen–Perylenediimide Conjugate as an Efficient Base Sensor with Solvatochromic Property
Authors: Pramanik Bapan , Mondal Julfikar Hassan , Singha Nilotpal , Ahmed Sahnawaz , Mohanty Jyotirmayee , Das Debapratim 
Published: November 2016

AbstractA viologen–perylenediimide conjugate, denoted PDEV, is prepared for efficient base sensing. The conjugate shows solvatochromic behavior as well. The base sensitivity of viologen is purposefully coupled with the emission property of perylenediimide (PDI) to lower the detection limit. PDEV shows base‐sensing ability at the ppb level, which is at least three orders of magnitude lower than those of previously reported sensors. The probe is sensitive toward solvent polarity and generates different shades of colors according to the polarity of the medium (solvent). The photophysical properties show a linear correlation with the solvent polarity, and this makes it an efficient solvatochromic agent. On the other hand, the generation of viologen radical cations by bases affects the aggregation and consequently the absorption and emission behavior of the PDI core. The effect of bases can also be visualized, because the probe generates different colors in the presence of bases, both under normal and under UV light. Organic amines can be detected even in the crystalline state, since the dark red color of the PDEV crystals changes to purple in a reversible fashion on exposure to amine vapors. An easy and practical paper‐based tool created by using the probe can efficiently be used to detect solvent polarity and presence of bases optically.
The Flavin–Tryptophan Dyad F10T as a Cryptochrome Model Compound: Synthesis and Photochemistry
Authors: Paul Shubhajit , Meng Lingqiang , Berger Stefan , Grampp Günter , Matysik Jörg , Wang Xiaojie 
Published: November 2016

AbstractMany animals sense the Earth's magnetic field and use it for navigation. It has been proposed that a light‐dependent quantum effect in cryptochrome photoreceptor proteins residing in the retina allow for such an iron‐free spin‐chemical compass. The primary photochemistry in cryptochromes and photolyases is assumed to be confined mainly in a flavin adenine dinucleotide (FAD) residue and three nearby tryptophan residues. Functional studies require model compounds allowing for direct structural modifications. Inspired by the structure of natural cryptochrome, a flavin–tryptophan dyad (F10T) has been synthesized. 1H photochemically induced dynamic nuclear polarization (photo‐CIDNP) NMR studies on F10T demonstrate the spin‐correlated radical‐pair formation through photoinduced electron transfer from donor (tryptophan) to acceptor (flavin) moieties under illumination with a white light source similar to sunlight. This is the first model compound of natural cryptochromes with a provision for controlled structural modifications.
Catalytic Transesterification of Starch with Plant Oils: A Sustainable and Efficient Route to Fatty Acid Starch Esters
Authors: Söyler Zafer , Meier Michael A. R. 
Published: November 2016

AbstractThe transesterification of maize starch with olive oil or high oleic sunflower oil was studied under homogeneous conditions in the presence of 1,5,7‐triazabicyclo[4.4.0]dec‐5‐ene (TBD) as catalyst. Most importantly, this method used two renewable resources directly, without any pretreatment or derivatization, for the synthesis of polymeric materials with desirable properties. Moreover, the solvent, oils, and catalyst could be recovered through facile work‐up and reused for further modifications. The obtained fatty acid starch esters (FASEs) were highly soluble in common organic solvents and were thoroughly characterized. Degrees of substitution (DS) were calculated using31P NMR spectroscopy, and DS values of approximately 1.3 were obtained. Differential scanning calorimetry analysis revealed thermal transitions of the modified starches at approximately 80–90 °C. Films were produced from these FASEs, and their hydrophobic surfaces were characterized using contact‐angle measurements. Furthermore, mechanical properties were examined using tensile strength measurements and showed approximately 40 and 80 % elongation at break for modified maize starch and modified amylose from maize, respectively.
Dry‐Deposited Transparent Carbon Nanotube Film as Front Electrode in Colloidal Quantum Dot Solar Cells
Authors: Zhang Xiaoliang , Aitola Kerttu , Hägglund Carl , Kaskela Antti , Johansson Malin B. , Sveinbjörnsson Kári , Kauppinen Esko I. , Johansson Erik M. J. 
Published: November 2016

AbstractSingle‐walled carbon nanotubes (SWCNTs) show great potential as an alternative material for front electrodes in photovoltaic applications, especially for flexible devices. In this work, a press‐transferred transparent SWCNT film was utilized as front electrode for colloidal quantum dot solar cells (CQDSCs). The solar cells were fabricated on both glass and flexible substrates, and maximum power conversion efficiencies of 5.5 and 5.6 %, respectively, were achieved, which corresponds to 90 and 92 % of an indium‐doped tin oxide (ITO)‐based device (6.1 %). The SWCNTs are therefore a very good alternative to the ITO‐based electrodes especially for flexible solar cells. The optical electric field distribution and optical losses within the devices were simulated theoretically and the results agree with the experimental results. With the optical simulations that were performed it may also be possible to enhance the photovoltaic performance of SWCNT‐based solar cells even further by optimizing the device configuration or by using additional optical active layers, thus reducing light reflection of the device and increasing light absorption in the quantum dot layer.
Variation of cytopathologists' use of the indeterminate diagnostic categories “atypical” and “suspicious for malignancy” in the cytologic diagnosis of solid pancreatic lesions on endoscopic ultrasound‐guided fine‐needle aspirates
Authors: Virk Renu K. , Gamez Roberto , Mehrotra Swati , Atieh Mohammed , Barkan Güliz A. , Wojcik Eva M. , Pambuccian Stefan E. 
Published: November 2016

Indeterminate cytologic diagnoses in endoscopic ultrasound guided fine needle aspiration biopsy (EUS‐FNA) of solid pancreatic lesions include the diagnostic categories “atypical” (ATY) and “suspicious for malignancy” (SUSP), which are used at variable rates and are associated with variable underlying risk of malignancy. The aim of this study was to determine individual cytopathologists' rates of indeterminate diagnoses in EUS‐FNA of solid pancreatic lesions and their relationship to cytopathologists' experience and volume of pancreatic EUS‐FNA examined, as well as the potential impact of departmental consensus review on indeterminate diagnoses.DesignThe diagnostic rates of ATY and SUSP and their underlying risk of malignancy were calculated for six cytopathologists who diagnosed 1,114 of 1,225 EUS‐FNA of solid pancreatic lesions from 1/1/2001 to 9/15/2014, and were then compared for the periods before and after the implementation of departmental consensus review during 2009.ResultsThe six cytopathologists diagnosed 10% of cases as indeterminate; 82 (7.4%) as “atypical” and 29 (2.6%) as “suspicious”. The individual cytopathologists' indeterminate diagnosis rates varied twofold (6.67–12.80%) and did not correlate with their experience, total or annual volume of EUS‐FNAs. Of the 56/99 (56.57%) cases with follow‐up, the underlying rate of malignancy was 47% (35/75; for “atypical” and 87.5% (21/24); for “suspicious”). The underlying rates of malignancy were 33–67% for “atypical” and 80–100% for “suspicious” diagnoses made by individual cytopathologists. The rate of indeterminate diagnoses decreased from 11.55 to 7.88% after the implementation of departmental consensus review.ConclusionIndividual cytopathologists' rates of indeterminate diagnoses and their significance vary; however, consensus review is helpful in reducing these rates. Diagn. Cytopathol. 2017;45:3–13. © 2016 Wiley Periodicals, Inc.