bluuebunny/crossref_metadata_2025_split huggingface dataset:
Click‐Tag and Amine‐Tag: Chemical Tag Approaches for Efficient Protein Labeling In Vitro and on Live Cells using the Naturally Split Npu DnaE Intein
Authors: Schütz Vivien , Mootz Henning D. 
Published: March 2014

AbstractProtein labeling with synthetic moieties remains in many cases a technically challenging or unresolved task. Two new and simple concepts are presented. In both approaches, a very short tag of only a few amino acids is prepared with the desired chemical modification and, in a second step, it is transferred to the protein of interest by protein trans‐splicing. For the amine‐tag, a recombinant intein fragment free of lysine residues was generated such that the amine group of the N terminus could be selectively modified with regular amine‐reactive reagents. Thus, standard bioconjugation procedures without any chemical synthesis could be applied without modification of lysines in the protein of interest. For the click‐tag, protein trans‐splicing was combined with unnatural amino acid mutagenesis and subsequent bioorthogonal side chain modification, as demonstrated for click chemistry using p‐azidophenylalanine. By the two‐step strategy, exposure of the protein of interest to the copper catalyst was avoided.
Functionalizing Designer DNA Crystals with a Triple‐Helical Veneer
Authors: Rusling David A. , Chandrasekaran Arun Richard , Ohayon Yoel P. , Brown Tom , Fox Keith R. , Sha Ruojie , Mao Chengde , Seeman Nadrian C. 
Published: March 2014

AbstractDNA is a very useful molecule for the programmed self‐assembly of 2D and 3D nanoscale objects.1 The design of these structures exploits Watson–Crick hybridization and strand exchange to stitch linear duplexes into finite assemblies.2–4 The dimensions of these complexes can be increased by over five orders of magnitude through self‐assembly of cohesive single‐stranded segments (sticky ends).5, 6 Methods that exploit the sequence addressability of DNA nanostructures will enable the programmable positioning of components in 2D and 3D space, offering applications such as the organization of nanoelectronics,7 the direction of biological cascades,8 and the structure determination of periodically positioned molecules by X‐ray diffraction.9 To this end we present a macroscopic 3D crystal based on the 3‐fold rotationally symmetric tensegrity triangle3, 6 that can be functionalized by a triplex‐forming oligonucleotide on each of its helical edges.
Competition Between Concerted and Stepwise Dynamics in the Triplet Di‐π‐Methane Rearrangement
Authors: Jiménez‐Osés Gonzalo , Liu Peng , Matute Ricardo A. , Houk Kendall N. 
Published: March 2014

AbstractThe molecular dynamics of the triplet‐state Zimmerman di‐π‐methane rearrangement of dibenzobarrelene were computed with B3LYP and M06‐2X density functionals. All productive quasiclassical trajectories involve sequential formation and cleavage of CC bonds and an intermediate with lifetimes ranging from 13 to 1160 fs. Both dynamically concerted and stepwise trajectories are found. The average lifetime of this intermediate is significantly shorter than predicted by either transition‐state theory or the Rice–Ramsperger–Kassel–Marcus model, thus indicating the non‐statistical nature of the reaction mechanism.
Hydrophobes Schalten einer doppellagigen DNA‐Origami‐Struktur
Authors: List Jonathan , Weber Michael , Simmel Friedrich C. 
Published: March 2014

AbstractAmphiphile Moleküle neigen in wässriger Lösung zur Aggregation. Wir zeigen, dass eine solche Aggregationswechselwirkung dazu genutzt werden kann, einlagige Cholesterin‐funktionalisierte DNA‐Origami‐Strukturen in “Sandwich”‐artige Doppellagenstrukturen zu falten, in deren Inneren die Cholesterin‐Modifikationen verborgen werden. Die DNA‐Strukturen entfalten sich sowohl nach Zugabe des Tensids Tween 80 als auch in Gegenwart von Lipidmembranen. Die Kinetik des Entfaltungsprozesses lässt sich mit einer gestreckten Exponentialfunktion beschreiben. Es wird auch gezeigt, wie sich das hydrophobe Schalten mit einem Schlüssel‐Schloss‐Mechanismus kombinieren lässt, wodurch das Entfalten der DNA‐Sandwiches von einem zusätzlichen molekularen Signal, z. B. einer spezifischen DNA‐Sequenz, abhängig gemacht werden kann.
Spatial and Directional Control over Self‐Assembly Using Catalytic Micropatterned Surfaces
Authors: Olive Alexandre G. L. , Abdullah Nor Hakimin , Ziemecka Iwona , Mendes Eduardo , Eelkema Rienk , van Esch Jan H. 
Published: March 2014

AbstractCatalyst‐assisted self‐assembly is widespread in nature to achieve spatial control over structure formation. Reported herein is the formation of hydrogel micropatterns on catalytic surfaces. Gelator precursors react on catalytic sites to form building blocks which can self‐assemble into nanofibers. The resulting structures preferentially grow where the catalyst is present. Not only is a first level of organization, allowing the construction of hydrogel micropatterns, achieved but a second level of organization is observed among fibers. Indeed, fibers grow with their main axis perpendicular to the substrate. This feature is directly linked to a unique mechanism of fiber formation for a synthetic system. Building blocks are added to fibers in a confined space at the solid–liquid interface.
Total Synthesis of Homogeneous Variants of Hirudin P6: A Post‐Translationally Modified Anti‐Thrombotic Leech‐Derived Protein
Authors: Hsieh Yves S. Y. , Wijeyewickrema Lakshmi C. , Wilkinson Brendan L. , Pike Robert N. , Payne Richard J. 
Published: March 2014

AbstractHirudin P6 is a leech‐derived anti‐thrombotic protein which possesses two post‐translational modifications, O‐glycosylation and tyrosine sulfation. In this study we report the ligation‐based synthesis of a library of hirudin P6 proteins possessing homogeneous glycosylation and sulfation modifications. The nature of the modifications incorporated was shown to have a drastic effect on inhibition against both the fibrinogenolytic and amidolytic activities of thrombin and thus highlights a potential means for attenuating the biological activity of the protein.
Phosphoryl‐Rich Flame‐Retardant Ions (FRIONs): Towards Safer Lithium‐Ion Batteries
Authors: Rectenwald Michael F. , Gaffen Joshua R. , Rheingold Arnold L. , Morgan Alexander B. , Protasiewicz John D. 
Published: March 2014

AbstractThe functionalized catecholate, tetraethyl (2,3‐dihydroxy‐1,4‐phenylene)bis(phosphonate) (H2‐DPC), has been used to prepare a series of lithium salts Li[B(DPC)(oxalato)], Li[B(DPC)2], Li[B(DPC)F2], and Li[P(DPC)3]. The phosphoryl‐rich character of these anions was designed to impart flame‐retardant properties for their use as potential flame‐retardant ions (FRIONs), additives, or replacements for other lithium salts for safer lithium‐ion batteries. The new materials were fully characterized, and the single‐crystal structures of Li[B(DPC)(oxalato)] and Li[P(DPC)3] have been determined. Thermogravimetric analysis of the four lithium salts show that they are thermally stable up to around 200 °C. Pyrolysis combustion flow calorimetry reveals that these salts produce high char yields upon combustion.
Omaezallene from Red Alga Laurencia sp.: Structure Elucidation, Total Synthesis, and Antifouling Activity
Authors: Umezawa Taiki , Oguri Yuko , Matsuura Hiroshi , Yamazaki Shohei , Suzuki Masahiro , Yoshimura Erina , Furuta Takeshi , Nogata Yasuyuki , Serisawa Yukihiko , Matsuyama‐Serisawa Kazuyo , Abe Tsuyoshi , Matsuda Fuyuhiko , Suzuki Minoru , Okino Tatsufumi 
Published: March 2014

AbstractNatural antifouling products have been the subject of considerable attention. We screened marine algae for antifouling activity and discovered omaezallenes, the new bromoallene‐containing natural products isolated from the red alga Laurencia sp. Described is the isolation, structure elucidation, and total syntheses of omaezallenes. The relative and absolute configurations of natural omaezallenes were unambiguously established through total synthesis. The antifouling activities and ecotoxicity of omaezallenes were also evaluated.
Characterization and mechanical properties of exfoliated graphite nanoplatelets reinforced polyethylene terephthalate/polypropylene composites
Authors: Inuwa I. M. , Hassan Azman , Samsudin S. A. , Haafiz M. K. Mohamad , Jawaid M. , Majeed K. , Razak N. C. Abdul 
Published: March 2014

ABSTRACTRecently, graphene and its derivatives have been used to develop polymer composites with improved or multifunctional properties. Exfoliated graphite nanoplatelets (GNP) reinforced composite materials based on blend of polyethylene terephthalate (PET), and polypropylene (PP) compatibilized with styrene–ethylene–butylene–styrene‐g‐maleic anhydride is prepared by melt extrusion followed by injection molding. Characterization of the composites' microstructure and morphology was conducted using field emission scanning electron microscopy, transmission electron microscopy (TEM), X‐ray diffraction analysis (XRD), and Fourier transform infrared spectroscopy (FTIR). Tensile and impact strengths of test specimens were evaluated and the results showed maximum values at 3phr GNP in both the cases. Morphological studies showed that the GNPs were uniformly dispersed within the matrix. Results from XRD analysis showed uniformly dispersed GNPs, which may not have been substantially exfoliated. FTIR spectroscopy did not show any significant change in the peak positions to suggest definitive chemical interaction between GNP and the matrix. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40582.
Prediction of long‐term mechanical properties of PVDF/BaTiO3 nanocomposite
Authors: Goodarzi Vahabodin , Kokabi Mehrdad , Razzaghi Kashani Mehdi , Reza Bahramian Ahmad 
Published: March 2014

ABSTRACTLow elastic modulus of polyvinylidene fluoride (PVDF) is a major drawback that can be compensated by adding nanoparticles. This work reports the long‐term mechanical behavior of PVDF nanocomposite containing BaTiO3 nanoparticle that is evaluated by creep test. The nanocomposite morphology was characterized by scanning and transmission electron microscopy techniques. The dynamic mechanical analysis (DMA) was employed to study the viscoelastic behavior of nanocomposite in a wide range of temperatures and frequencies. According to the creep tests, nanocomposite reduced the rate of the creep compliance at different temperatures. Moreover, the creep compliance for the nanocomposite sample decreased slightly in comparison with neat PVDF. Comparing the Burger's model and experimental results, the elastic and viscous parameters revealed the exactly opposite behavior with increasing temperature. The effect of frequencies on storage moduli of samples was investigated based on time–temperature superposition (TTS) method. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40596.
Potential and Limits of Biodegradation Processes for the Removal of Organic Xenobiotics from Wastewaters
Authors: Dionisi Davide 
Published: March 2014

AbstractIn the removal of organic xenobiotics from wastewaters, biodegradation is an interesting alternative to conventional physical and chemical processes. Biodegradation in biological wastewater treatment plants has the potential advantages of removing the xenobiotics from the environment, transforming them into nontoxic products such as carbon dioxide and new biomass, and being relatively low in cost. Many xenobiotics have been found to be biodegradable as sole carbon and energy source under aerobic conditions, while under anaerobic conditions many chlorinated hydrocarbons can be biodegraded by reductive dechlorination processes. The main limits of biodegradation processes are the limited time for adaptation to the xenobiotics, the very low xenobiotics concentration in the influent, the competition with abiotic removal mechanisms, the limited availability of external substrates for cometabolism, and the intrinsic nonbiodegradability. Existing biological wastewater treatment processes can be modified by using higher values of the solids retention time, bioaugmentation, addition of readily biodegradable substrates to support cometabolism, and the use of anaerobic‐aerobic processes.
Pyrolyzed Polyaniline–Graphene Nanosheets with Enhanced Lithium‐Storage Properties: Preparation and Characterization
Authors: Wang Yong‐Chen , Zhu Bi‐Yu , Ni Jiang‐Feng , Zhang Li , Wang Hai‐Bo , Gao Li‐Jun 
Published: March 2014

AbstractPyrolyzed polyaniline–graphene nanosheets (PA–GNS) are examined as a lithium‐storage material. The PA–GNS composite is synthesized through heat treatment of polyaniline–graphite oxide precursors under a H2/Ar atmosphere at 850 °C. Scanning and transmission electron microscopies, X‐ray diffraction, Raman spectroscopy, and X‐ray photoelectron spectroscopy are employed to characterize the prepared PA–GNS composite in comparison with pristine graphene nanosheets (GNS). Galvanostatic charge/discharge experiments show that PA–GNS exhibits an improved rate and cycle capability at both 25 and 55 °C. It is also found from electrical resistivity tests and electrochemical impedance spectroscopy measurements that the PA–GNS composite demonstrates a higher vertical electronic conductivity and lower charge‐transfer resistance than GNS, and it is concluded that modifying GNS with pyrolyzed polyaniline is an effective way to enhance the rate capability and cyclability of GNS.
Evidence of Facilitated Electron Transfer on Hydrogenated Self‐Doped TiO2 Nanocrystals
Authors: Minguzzi Alessandro , Sánchez‐Sánchez Carlos M. , Gallo Alessandro , Montiel Vicente , Rondinini Sandra 
Published: March 2014

AbstractTiO2 nanocrystals are widely used as semiconductor photocatalysts, despite their limited sunlight absorption. The hydrogenation of TiO2 has recently been proposed as a promising new method for enhancing its solar‐driven photocatalytic activity. But, the ability of this hydrogenated TiO2 to transfer electrons across the interface has not been studied in detail. For this reason, the electrochemical properties of hydrogenated self‐doped TiO2−x nanocrystals are studied and compared to commercial anatase TiO2 nanocrystals. Here we use cyclic voltammetry (CV) and scanning electrochemical microscopy (SECM) as tools to characterize the semiconductors and, in particular, to evaluate their reactivity towards redox species in solution. CV is used to evaluate the doping level; we propose the co‐presence of permanent defects, induced by the hydrogenation reductive treatment, as well as temporary ones, induced electrochemically. By using ferrocenemethanol as the redox‐active species, SECM, in a substrate/tip configuration, demonstrates that the electron transfer is facilitated on hydrogenated self‐doped TiO2−x by a potential‐shift of approximately 0.3–0.4 V.
Heavy‐Atom Tunneling in the Ring Opening of a Strained Cyclopropene at Very Low Temperatures
Authors: Ertelt Melanie , Hrovat David A. , Borden Weston Thatcher , Sander Wolfram 
Published: March 2014

AbstractThe highly strained 1H‐bicyclo[3.1.0]‐hexa‐3,5‐dien‐2‐one 1 is metastable, and rearranges to 4‐oxacyclohexa‐2,5‐dienylidene 2 in inert gas matrices (neon, argon, krypton, xenon, and nitrogen) at temperatures as low as 3 K. The kinetics for this rearrangement show pronounced matrix effects, but in a given matrix, the reaction rate is independent of temperature between 3 and 20 K. This temperature independence means that the activation energy is zero in this temperature range, indicating that the reaction proceeds through quantum mechanical tunneling from the lowest vibrational level of the reactant. At temperatures above 20 K, the rate increases, resulting in curved Arrhenius plots that are also indicative of thermally activated tunneling. These experimental findings are supported by calculations performed at the CASSCF and CASPT2 levels by using the small‐curvature tunneling (SCT) approximation.
Exploring the Synthesis of a New Group of Chiral Ammonium Salts with Specific Configurations at the Stereogenic Nitrogen Centers
Authors: Eckert Prisca K. , Golz Christopher , Degen Patrick , Werner Cornelia , Rehage Heinz , Strohmann Carsten 
Published: March 2014

AbstractA group of new chiral dications with a fixed, specific configuration at the stereogenic nitrogen center was created. Stereoselective synthesis and recrystallization give the diastereomerically and enantiomerically pure dications, including a chiral amphiphile with surface‐active properties.
Delivery of Suramin as an Antiviral Agent through Liposomal Systems
Authors: Mastrangelo Eloise , Mazzitelli Stefania , Fabbri Jacopo , Rohayem Jacques , Ruokolainen Janne , Nykänen Antti , Milani Mario , Pezzullo Margherita , Nastruzzi Claudio , Bolognesi Martino 
Published: March 2014

AbstractNorovirus RNA‐dependent RNA polymerase (RdRp) is a promising target enzyme for the development of new antiviral drugs. Starting from the crystal structure of norovirus RdRp, we had previously performed an in silico docking search using a library of low‐molecular‐weight compounds that enabled us to select molecules with predicted enzyme inhibitory activity. Among these, the polysulfonated naphthylurea suramin proved to inhibit in vitro both murine and human norovirus polymerases, with IC50 values in the low micromolar range. The negatively charged inhibitor, however, displayed poor cell permeability in cell‐based experiments. Therefore, we produced different suramin‐loaded liposome formulations and evaluated their activities in cell‐based assays using murine norovirus cultivated in RAW 264.7 macrophages, as a model for norovirus genus. The results obtained show that suramin, when delivered through liposomes, can effectively inhibit murine norovirus replication.
Synthesis and DNA Cleavage Activity of Bis‐3‐chloropiperidines as Alkylating Agents
Authors: Zuravka Ivonne , Roesmann Rolf , Sosic Alice , Wende Wolfgang , Pingoud Alfred , Gatto Barbara , Göttlich Richard 
Published: March 2014

AbstractNitrogen mustards are an important class of bifunctional alkylating agents routinely used in chemotherapy. They react with DNA as electrophiles through the formation of highly reactive aziridinium ion intermediates. The antibiotic 593A, with potential antitumor activity, can be considered a naturally occurring piperidine mustard containing a unique 3‐chloropiperidine ring. However, the total synthesis of this antibiotic proved to be rather challenging. With the aim of designing simplified analogues of this natural product, we developed an efficient bidirectional synthetic route to bis‐3‐chloropiperidines joined by flexible, conformationally restricted, or rigid diamine linkers. The key step involves an iodide‐catalyzed double cyclization of unsaturated bis‐N‐chloroamines to simultaneously generate both piperidine rings. Herein we describe the synthesis and subsequent evaluation of a series of novel nitrogen‐bridged bis‐3‐chloropiperidines, enabling the study of the impact of the linker structure on DNA alkylation properties. Our studies reveal that the synthesized compounds possess DNA alkylating abilities and induce strand cleavage, with a strong preference for guanine residues.
Thyroid “Atypia of undetermined significance” with nuclear atypia has high rates of malignancy and BRAF mutation
Authors: Park Hyo Jin , Moon Jae Hoon , Yom Cha Kyong , Kim Kyu Hyung , Choi June Young , Choi Sang Il , Ahn Soon‐Hyun , Jeong Woo‐Jin , Lee Won Woo , Park So Yeon 
Published: March 2014

BACKGROUND“Atypia of undetermined significance” (AUS) in the Bethesda System for Reporting Thyroid Cytopathology is a heterogeneous category for cases that cannot be easily classified into benign, suspicious, or malignant. This study evaluated whether cytomorphology‐based subcategorization could better predict the malignancy risk in cases designated as AUS, and how the subcategories correlated with BRAF mutation status in thyroid fine‐needle aspirates (FNA).METHODSOf 3589 cases of thyroid FNA diagnosed at the authors' institution in Seongnam, Korea, from January 2010 to December 2011, 331 cases of AUS were reviewed and subcategorized based on cytomorphological features, including nuclear atypia (NA), microfollicle formation (MF), Hürthle cell change (HC), and others (O). The malignancy rate of each subcategory was calculated using cases with histologic follow‐up. Pyrosequencing was conducted to detect BRAF mutations.RESULTSMalignancy was histologically proven in 23.3% (77 of 331) of cases diagnosed as AUS. In cytomorphology‐based subcategories, the rate of malignancy was 30.8% (66 of 214) for AUS‐NA, 14.5% (8 of 55) for AUS‐O, 4.8% (2 of 42) for AUS‐MF, and 5% (1 of 20) for AUS‐HC. The BRAF V600E mutation was found in 40% (48 of 120) of AUS‐NA, 30.8% (4 of 13) of AUS‐HC, 6.7% (1 of 15) of AUS‐O, and 2.8% (1 of 35) of AUS‐MF.CONCLUSIONSThe AUS‐NA subcategory was associated with the highest risk of malignancy and the greatest frequency of BRAF V600E (substitution of valine to glutamic acid at position 600) mutation. These findings suggest that subcategorization of AUS by cytomorphology and BRAF V600E mutation status is important for predicting the risk of malignancy. Cancer (Cancer Cytopathol) 2014;122:512–520. © 2014 American Cancer Society.
Large Magnetocaloric Effect, Moment, and Coercivity Enhancement after Coating Ni Nanoparticles with Ag
Authors: Srinath Sanyadanam , Poddar Pankaj , Das Raja , Sidhaye Deepti , Prasad Bhagavatula Lakshmi Vara , Gass James , Srikanth Hariharan 
Published: March 2014

AbstractWe observe a large magnetocaloric effect in monodisperse Ni and NicoreAgshell nanoparticles in the superparamagnetic region. The organically passivated Ni nanospheres show a large magnetic entropy change of 0.9 J kg−1 K for a 3 T magnetic field change. In comparison to the surfactant‐coated Ni nanoparticles, the NicoreAgshell nanoparticles show an enhanced coercivity, magnetization, and magnetocaloric effect (1.3 kg K for a 3 T magnetic field change). The coercivity at 10 K increases from 360 Oe for Ni nanoparticles to nearly 610 Oe for NicoreAgshell particles. This large enhancement is attributed to the enhanced inter‐particle interaction, which is mediated by the metallic shell, over the relatively weaker dipolar interaction in the surfactant‐coated Ni nanoparticles, and to modification of the surface spin structure.
Role of Edge Geometry and Magnetic Interaction in Opening Bandgap of Low‐Dimensional Graphene
Authors: Zhu Yongfu , Lian Jianshe , Jiang Qing 
Published: March 2014

AbstractBy using a size‐dependent cohesive energy formula for two‐dimensional coordination materials, the bandgap openings of ideal graphene quantum dots (GQDs) and nanoribbons (GNRs) have been investigated systematically regarding dimension, edge geometry, and magnetic interaction. Results demonstrate that the bandgap openings in GQDs can be dominated by the change of atomic cohesive energy. Relative to zigzag GQDs, the openings in the armchair ones are more substantial, attributed to its edge instability. The change of cohesive energy can also lead to bandgap openings in zigzag and armchair GNRs. The contribution from the interedge magnetic interaction in zigzag GNRs is negligible, while the cohesive‐energy induced openings in armchair GNRs can oscillate according to the so‐called full‐wavelength effect, depending on the width. The model prediction provides physicochemical insight into the bandgap openings in graphene.