bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Breathing Atom‐Transfer Radical Polymerization: Fully Oxygen‐Tolerant Polymerization Inspired by Aerobic Respiration of Cells
Authors: Enciso Alan E. , Fu Liye , Russell Alan J. , Matyjaszewski Krzysztof 
Published: December 2017

AbstractThe first well‐controlled aqueous atom‐transfer radical polymerization (ATRP) conducted in the open air is reported. This air‐tolerant ATRP was enabled by the continuous conversion of oxygen to carbon dioxide catalyzed by glucose oxidase (GOx), in the presence of glucose and sodium pyruvate as sequential sacrificial substrates. Controlled polymerization using initiators for continuous activator regeneration (ICAR) ATRP of oligo(ethylene oxide) methyl ether methacrylate (OEOMA, Mn=500) yielded polymers with low dispersity (1.09≤Đ≤1.29) and molecular weights (MWs) close to theoretical values in the presence of pyruvate. Without added pyruvates, lower MWs were observed due to generation of new chains by H2O2 formed by reaction of O2 with GOx. Successful chain extension of POEOMA500 macroinitiator with OEOMA300 (Đ≤1.3) and Bovine Serum Albumin bioconjugates (Đ≤1.22) confirmed a well‐controlled polymerization. The reactions in the open air in larger scale (25 mL) were also successful.
The Molecular Structure of gauche‐1,3‐Butadiene: Experimental Establishment of Non‐planarity
Authors: Baraban Joshua H. , Martin‐Drumel Marie‐Aline , Changala P. Bryan , Eibenberger Sandra , Nava Matthew , Patterson David , Stanton John F. , Ellison G. Barney , McCarthy Michael C. 
Published: December 2017

AbstractThe planarity of the second stable conformer of 1,3‐butadiene, the archetypal diene for the Diels–Alder reaction in which a planar conjugated diene and a dienophile combine to form a ring, is not established. The most recent high level calculations predicted the species to adopt a twisted, gauche structure owing to steric interactions between the inner terminal hydrogens rather than a planar, cis structure favored by the conjugation of the double bonds. The structure cis‐1,3‐butadiene is unambiguously confirmed experimentally to indeed be gauche with a substantial dihedral angle of 34°, in excellent agreement with theory. Observation of two tunneling components indicates that the molecule undergoes facile interconversion between two equivalent enantiomeric forms. Comparison of experimentally determined structures for gauche‐ and trans‐butadiene provides an opportunity to examine the effects of conjugation and steric interactions.
Bioorthogonal Cycloadditions with Sub‐Millisecond Intermediates
Authors: Qing Yujia , Pulcu Gökçe Su , Bell Nicholas A. W. , Bayley Hagan 
Published: December 2017

AbstractTetrazine‐ and sydnone‐based click reactions have emerged as important bioconjugation strategies with fast kinetics and N2 or CO2 as the only byproduct. Mechanistic studies of these reactions have focused on the initial rate‐determining cycloaddition steps. The subsequent N2 or CO2 release from the bicyclic intermediates has been approached mainly through computational studies, which have predicted lifetimes of femtoseconds. In the present study, bioorthogonal cycloadditions involving N2 or CO2 extrusion have been examined experimentally at the single‐molecule level by using a protein nanoreactor. At the resolution of this approach, the reactions appeared to occur in a single step, which places an upper limit on the lifetimes of the intermediates of about 80 μs, which is consistent with the computational work.
Controlling the Polymer Microstructure in Anionic Polymerization by Compartmentalization
Authors: Rieger Elisabeth , Blankenburg Jan , Grune Eduard , Wagner Manfred , Landfester Katharina , Wurm Frederik R. 
Published: December 2017

AbstractAn ideal random anionic copolymerization is forced to produce gradient structures by physical separation of two monomers in emulsion compartments. One monomer (M) is preferably soluble in the droplets, while the other one (D) prefers the continuous phase of a DMSO‐in‐cyclohexane emulsion. The living anionic copolymerization of two activated aziridines is thus confined to the DMSO compartments as polymerization occurs selectively in the droplets. Dilution of the continuous phase adjusts the local concentration of monomer D in the droplets and thus the gradient of the resulting copolymer. The copolymerizations in emulsion are monitored by real‐time 1H NMR kinetics, proving a change of the reactivity ratios of the two monomers upon dilution of the continuous phase from ideal random to adjustable gradients by simple dilution.
Reductive Amination by Photoredox Catalysis and Polarity‐Matched Hydrogen Atom Transfer
Authors: Guo Xingwei , Wenger Oliver S. 
Published: December 2017

AbstractThe excitation of a RuII photosensitizer in the presence of ascorbic acid leads to the reduction of iminium ions to electron‐rich α‐aminoalkyl radical intermediates, which are rapidly converted into reductive amination products by thiol‐mediated hydrogen atom transfer (HAT). As a result, the reductive amination of carbonyl compounds with amines by photoredox catalysis proceeds in good to excellent yields and with broad substrate scope and good functional group tolerance. The three key features of this work are 1) the rapid interception of electron‐rich α‐aminoalkyl radical intermediates by polarity‐matched HAT in a photoredox reaction, 2) the method of reductive amination by photoredox catalysis itself, and 3) the application of this new method for temporally and spatially controlled reactions on a solid support, as demonstrated by the attachment of a fluorescent dye on an activated cellulose support by photoredox‐catalyzed reductive amination.
Dynamic Covalent Chemistry within Biphenyl Scaffolds: Reversible Covalent Bonding, Control of Selectivity, and Chirality Sensing with a Single System
Authors: Ni Cailing , Zha Daijun , Ye Hebo , Hai Yu , Zhou Yuntao , Anslyn Eric V. , You Lei 
Published: December 2017

AbstractAxial chirality is a prevalent and important phenomenon in chemistry. Herein we report a combination of dynamic covalent chemistry and axial chirality for the development of a versatile platform for the binding and chirality sensing of multiple classes of mononucleophiles. An equilibrium between an open aldehyde and its cyclic hemiaminal within biphenyl derivatives enabled the dynamic incorporation of a broad range of alcohols, thiols, primary amines, and secondary amines with high efficiency. Selectivity toward different classes of nucleophiles was also achieved by regulating the distinct reactivity of the system with external stimuli. Through induced helicity as a result of central‐to‐axial chirality transfer, the handedness and ee values of chiral monoalcohol and monoamine analytes were reported by circular dichroism. The strategies introduced herein should find application in many contexts, including assembly, sensing, and labeling.
A Keggin Polyoxometalate Shows Water Oxidation Activity at Neutral pH: POM@ZIF‐8, an Efficient and Robust Electrocatalyst
Authors: Mukhopadhyay Subhabrata , Debgupta Joyashish , Singh Chandani , Kar Aranya , Das Samar K. 
Published: December 2017

AbstractKeggin‐type polyoxometalate anions [XM12O40]n− are versatile, as their applications in interdisciplinary areas show. The Keggin anion [CoW12O40]6− turns into an efficient and robust electrocatalyst upon its confinement in the well‐defined void space of ZIF‐8, a metal–organic framework (MOF). [H6CoW12O40]@ZIF‐8 is so stable to water oxidation that it retains its initial activity even after 1000 catalytic cycles. The catalyst has a turnover frequency (TOF) of 10.8 mol O2(mol Co)−1 s−1, one of the highest TOFs for electrocatalytic oxygen evolution at neutral pH. Controlled experiments rule out the chances of formation and participation of CoOx in this electrocatalyic water oxidation.
Comparing laser diffraction and optical microscopy for characterizing superabsorbent polymer particle morphology, size, and swelling capacity
Authors: Davis Cole R. , Kelly Stacey L. , Erk Kendra A. 
Published: December 2017

ABSTRACTIn this study, we determined the accuracy and practicality of using optical microscopy (OM) and laser diffraction (LD) to characterize hydrogel particle morphology, size, and swelling capacity (Q). Inverse‐suspension‐polymerized polyacrylamide particles were used as a model system. OM and LD showed that the average particle diameter varied with the mixing speed during synthesis for the dry (10–120 μm) and hydrated (34–240 μm) particles. The LD volume and number mean diameters showed that a few large particles were responsible for the majority of the water absorption. Excess water present in the gravimetric swelling measurements led to larger Qs (8.2 ± 0.37 g/g), whereas the volumetric measurements with OM and LD resulted in reduced capacities (6.5 ± 3.8 and 5.7 ± 3.9 g/g, respectively). Results from the individual particle swelling measurements with OM (5.2 ± 0.66 g/g) statistically confirmed that the volumetric methods resulted in a reduced and more accurate measurement of the Q than the gravimetric method. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46055.
Improving bonding strength between a hydrophilic coating layer and poly(ethylene terephthalate) braid for preparing mechanically stable braid‐reinforced hollow fiber membranes
Authors: Zhou Zhuang , Fang Li‐Feng , Wang Sheng‐Yao , Matsuyama Hideto 
Published: December 2017

ABSTRACTA braid‐reinforced hollow fiber membrane with mechanically stable coating layer was prepared by coating a blended polymer dope solution on an alkaline‐treated poly(ethylene terephthalate) (PET) braid. The alkaline treatment was carried out to endow the PET braid surface with more polar groups and better hydrophilicity. The results showed that the bonding strength between the hydrophilic coating layer and modified PET braid was about two times as great as that between the coating layer and original PET braid, while the pure water permeability (PWP) of the membrane remained unchanged when the PET braid was simply treated in 3 wt % potassium hydroxide (KOH) solution at 90 °C for 1 h or 1 wt % KOH solution for 6 h. The proposed modification approach proved to be a facile, low‐cost, and effective method to improve bonding strength between the coating layer and the braid, while other properties, such as PWP and morphology of the coating layer, of the braid‐reinforced hollow fiber membranes were not altered, indicating promising potential in membrane engineering. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46104
Design, synthesis, and biological evaluation of 1‐ethyl‐3‐(thiazol‐2‐yl)urea derivatives as Escherichia coli DNA gyrase inhibitors
Authors: Tomašič Tihomir , Barančoková Michaela , Zidar Nace , Ilaš Janez , Tammela Päivi , Kikelj Danijel 
Published: December 2017

AbstractDiscovery of novel DNA gyrase B inhibitors remains an attractive field in the search for new antibacterial drugs to overcome the known bacterial resistance mechanisms. In the present study, we designed and synthesized novel ethylurea derivatives of 4,5,6,7‐tetrahydrobenzo[1,2‐d]thiazole‐2,6‐diamine, 2‐(2‐aminothiazol‐4‐yl)acetic acid, and benzo[1,2‐d]thiazole‐2,6‐diamine and evaluated their Escherichia coli DNA gyrase inhibition. The most potent DNA gyrase inhibitors in the prepared library of compounds were benzo[1,2‐d]thiazoles 32–34, 36, and 37 with IC50 values in the low micromolar range. The most promising inhibitors identified were evaluated against selected Gram‐positive and Gram‐negative bacterial strains. Compound 33 showed a MIC of 50 μM against an E. coli efflux pump‐defective strain, which suggests that efflux decreases the on‐target concentrations of these compounds.
Thermoactivation of a cellobiohydrolase
Authors: Westh Peter , Borch Kim , Sørensen Trine , Tokin Radina , Kari Jeppe , Badino Silke , Cavaleiro Mafalda A. , Røjel Nanna , Christensen Stefan , Vesterager Cynthia S. , Schiano‐di‐Cola Corinna 
Published: December 2017

AbstractWe have measured activity and substrate affinity of the thermostable cellobiohydrolase, Cel7A, from Rasamsonia emersonii over a broad range of temperatures. For the wild type enzyme, which does not have a Carbohydrate Binding Module (CBM), higher temperature only led to moderately increased activity against cellulose, and we ascribed this to a pronounced, temperature induced desorption of enzyme from the substrate surface. We also tested a “high affinity” variant of R. emersonii Cel7A with a linker and CBM from a related enzyme. At room temperature, the activity of the variant was similar to the wild type, but the variant was more accelerated by temperature and about two‐fold faster around 70 °C. This better thermoactivation of the high‐affinity variant could not be linked to differences in stability or the catalytic process, but coincided with less desorption as temperature increased. Based on these observations and earlier reports on moderate thermoactivation of cellulases, we suggest that better cellulolytic activity at industrially relevant temperatures may be attained by engineering improved substrate affinity into enzymes that already possess good thermostability.
Engineering and cytosolic delivery of a native regulatory protein and its variants for modulation of ERK2 signaling pathway
Authors: Ryou Jeong‐Hyun , Sohn Yoo‐Kyoung , Kim Dong‐Gun , Kyeong Hyun‐Ho , Kim Hak‐Sung 
Published: December 2017

AbstractThe modulation of a cell signaling process using a molecular binder followed by an analysis of the cellular response is crucial for understanding its role in the cellular function and developing pharmaceuticals. Herein, we present the modulation of the ERK2‐mediated signaling pathway through the cytosolic delivery of a native regulatory protein for ERK2, that is, PEA‐15 (phosphoprotein enriched in astrocytes, 15 kDa), and its engineered variants using a bacterial toxin‐based delivery system. Based on biochemical and structural analyses, PEA‐15 variants with different phosphorylation sites and a high affinity for ERK2 were designed. Semi‐rational approach led to about an 830‐fold increase in the binding affinity of PEA‐15, resulting in more effective modulation of the ERK2‐mediated signaling. Our approach enabled an understanding of the cellular function of the ERK2‐mediated signaling process and the effect of PEA‐15 phosphorylation on its action as an ERK2 blocker. We demonstrated the utility and potential of our approach by showing an efficient cytosolic delivery of these PEA‐15 variants and the effective suppression of cell proliferation through the inhibition of the ERK2 function. The present approach can be used broadly for modulating the cell signaling processes and understanding their roles in cellular function, as well as for the development of therapeutics.
Simplicity at the cost of predictive accuracy in diffuse large B‐cell lymphoma: a critical assessment of the R‐IPI,IPI, andNCCN‐IPI
Authors: Biccler Jorne , Eloranta Sandra , de Nully Brown Peter , Frederiksen Henrik , Jerkeman Mats , Smedby Karin E. , Bøgsted Martin , El‐Galaly Tarec C. 
Published: December 2017

AbstractThe international prognostic index (IPI) and similar models form the cornerstone of clinical assessment in newly diagnosed diffuse large B‐cell lymphoma (DLBCL). While being simple and convenient to use, their inadequate use of the available clinical data is a major weakness. In this study, we compared performance of the International Prognostic Index (IPI) and its variations (R‐IPIandNCCN‐IPI) to a Cox proportional hazards (CPH) model using the same covariates in nondichotomized form. All models were tested in 4863 newly diagnosedDLBCLpatients from population‐based Nordic registers. TheCPHmodel led to a substantial increase in predictive accuracy as compared to conventional prognostic scores when evaluated by the area under the curve and other relevant tests. Furthermore, the generation of patient‐specific survival curves rather than assigning patients to one of few predefined risk groups is a relevant step toward personalized management and treatment. A test‐version is available on lymphomapredictor.org.
Development and Validation of 2D Difference Intensity Analysis for Chemical Library Screening by Protein‐Detected NMR Spectroscopy
Authors: Egner John M. , Jensen Davin R. , Olp Michael D. , Kennedy Nolan W. , Volkman Brian F. , Peterson Francis C. , Smith Brian C. , Hill R. Blake 
Published: December 2017

AbstractAn academic chemical screening approach was developed by using 2D protein‐detected NMR, and a 352‐chemical fragment library was screened against three different protein targets. The approach was optimized against two protein targets with known ligands: CXCL12 and BRD4. Principal component analysis reliably identified compounds that induced nonspecific NMR crosspeak broadening but did not unambiguously identify ligands with specific affinity (hits). For improved hit detection, a novel scoring metric—difference intensity analysis (DIA)—was devised that sums all positive and negative intensities from 2D difference spectra. Applying DIA quickly discriminated potential ligands from compounds inducing nonspecific NMR crosspeak broadening and other nonspecific effects. Subsequent NMR titrations validated chemotypes important for binding to CXCL12 and BRD4. A novel target, mitochondrial fission protein Fis1, was screened, and six hits were identified by using DIA. Screening these diverse protein targets identified quinones and catechols that induced nonspecific NMR crosspeak broadening, hampering NMR analyses, but are currently not computationally identified as pan‐assay interference compounds. The results established a streamlined screening workflow that can easily be scaled and adapted as part of a larger screening pipeline to identify fragment hits and assess relative binding affinities in the range of 0.3–1.6 mm. DIA could prove useful in library screening and other applications in which NMR chemical shift perturbations are measured.
NMR Study of Rcf2 Reveals an Unusual Dimeric Topology in Detergent Micelles
Authors: Zhou Shu , Pettersson Pontus , Brzezinski Peter , Ädelroth Pia , Mäler Lena 
Published: December 2017

AbstractThe Saccharomyces cerevisiae mitochondrial respiratory supercomplex factor 2 (Rcf2) plays a role in assembly of supercomplexes composed of cytochrome bc1 (complex III) and cytochrome c oxidase (complex IV). We expressed the Rcf2 protein in Escherichia coli, refolded it, and reconstituted it into dodecylphosphocholine (DPC) micelles. The structural properties of Rcf2 were studied by solution NMR, and near complete backbone assignment of Rcf2 was achieved. The secondary structure of Rcf2 contains seven helices, of which five are putative transmembrane (TM) helices, including, unexpectedly, a region formed by a charged 20‐residue helix at the C terminus. Further studies demonstrated that Rcf2 forms a dimer, and the charged TM helix is involved in this dimer formation. Our results provide a basis for understanding the role of this assembly/regulatory factor in supercomplex formation and function.
A study on Fuzzy C‐means application in Austronesian language cultural and creative product colors
Authors: Wang Ming‐Feng 
Published: December 2017

AbstractAs culture has brought unlimited possibility and business opportunities, the countries propose the cultural and creative industry to strengthen the distinctive feature of their own, to distinguish the cultural differences of every country, and to avoid assimilation of powerful countries and neighbor countries, thereby revitalize the economy of that country. In countries affected by Austronesian culture, such as Taiwan and New Zealand, the rules by the Western colonial powers caused impact of different cultural uniqueness, which led to cultural differences. It is important to figure out the way to integrate exclusive cultures into diverse cultures in order to identify the cultural features of the country, promote the country's culture to others and realize the goal of the cultural and creative industry. Therefore, the purpose of the study is to provide the application of Fuzzy C‐means on cultural and creative products for designers. Finally, through the result of the design of case, cultural and creative products developed from Taiwan and New Zealand, fulfilled the purpose that the theory has been realized in practice, and the products successfully entered the markets.
Toward improved aesthetics and data discrimination for treemaps via color schemes
Authors: Xie Yingtao , Lin Tao , Chen Rui , Chen Zhi 
Published: December 2017

AbstractIn this article, we present a novel treemap coloring method which can help users to analyze visual data more easily. Our method overcomes two major limitations of existing treemaps in that they are either aesthetically unpleasing or unable to readily discriminate data blocks with close sizes. Our study indicates that the use of proper color schemes can surprisingly address these two seemingly uncorrelated limitations simultaneously. To improve the aesthetic value of a treemap, we apply the color aesthetic model to treemap generation. To better the degree of data discrimination of similar data, based on the principle of expansive and contractive colors, we propose a novel quantitative color‐visually perceived area (C‐VPA) model via experimental methods. Furthermore, we combine these two models to derive a genetic algorithm‐based treemap coloring method. Our experimental results confirm the superiority of our method in terms of improved data discrimination and aesthetics of the treemaps.
Digitally reconstructing Van Gogh's Field with Irises near Arles part 3: Determining the original colors
Authors: Kirchner Eric , van der Lans Ivo , Ligterink Frank , Geldof Muriel , Megens Luc , Meedendorp Teio , Pilz Kathrin , Hendriks Ella 
Published: December 2017

AbstractIn earlier articles, we determined the spatial distributions and concentrations of all pigments used by Van Gogh in his painting Field with Irises near Arles. The colors of some pigments are expected to have changed over time, especially those of chrome yellow, cochineal, and eosin lake. For all pigments in this painting, we made physical paint reconstructions by following historical sources on raw materials and production processes, and we determined their optical properties. We combined this with pigment concentration maps to reconstruct the original colors of the painting digitally. When substituting the reconstruction paints into the calculations, we found that technical‐scientific data was not sufficient to resolve several issues. In those cases, discussions within the broad interdisciplinary team allowed us to make informed decisions. These issues refer to the representation of the sky area, and the original contributions of the red lake pigments to local colors. The digitally reconstructed colors of the painting show that due to discoloring of red lake pigments, the irises in the field have changed from a warm purple to purplish blue, and many pink spots in the field have turned to white. The range of yellows in the field has decreased and partly turned to dark brown. The digital reconstruction gives a better understanding of the color scheme used by Van Gogh when compared to remarks the artist made in letters when describing this painting. Also, the original color composition is seen to be aligned with color theories on which Van Gogh based his work.