bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Fluorescent Adenosine Analogue as a Substrate for an A‐to‐I RNA Editing Enzyme
Authors: Mizrahi Rena A. , Shin Dongwon , Sinkeldam Renatus W. , Phelps Kelly J. , Fin Andrea , Tantillo Dean J. , Tor Yitzhak , Beal Peter A. 
Published: June 2015

AbstractAdenosine to inosine RNA editing catalyzed by ADAR enzymes is common in humans, and altered editing is associated with disease. Experiments using substrate RNAs with adenosine analogues at editing sites are useful for defining features of the ADAR reaction mechanism. The reactivity of ADAR2 was evaluated with RNA containing the emissive adenosine analogue thieno[3,4‐d]‐6‐aminopyrimidine (thA). This nucleoside was incorporated into a mimic of the glutamate receptor B (GluR B) mRNA R/G editing site. We found that thA is recognized by AMV reverse transcriptase as A, and is deaminated rapidly by human ADAR2 to give thI. Importantly, ADAR reaction progress can be monitored by following the deamination‐induced change in fluorescence of the thA‐modified RNA. The observed high thA reactivity adds to our understanding of the structural features that are necessary for an efficient hADAR2 reaction. Furthermore, the new fluorescent assay is expected to accelerate mechanistic studies of ADARs.
Catalyst‐Switchable Regiocontrol in the Direct Arylation of Remote CH Groups in Pyrazolo[1,5‐a]pyrimidines
Authors: Bedford Robin B. , Durrant Steven J. , Montgomery Michelle 
Published: June 2015

AbstractThe regiodivergent palladium‐catalyzed CH arylation of pyrazolo[1,5‐a]pyrimidine has been achieved, wherein the switch in regioselectivity between positions C3 and C7 is under complete catalyst control. A phosphine‐containing palladium catalyst promotes the direct arylation at the most acidic position (C7), whereas a phosphine‐free catalyst targets the most electron‐rich position (C3).
Majority‐Rules‐Type Helical Poly(quinoxaline‐2,3‐diyl)s as Highly Efficient Chirality‐Amplification Systems for Asymmetric Catalysis
Authors: Ke Yuan‐Zhen , Nagata Yuuya , Yamada Tetsuya , Suginome Michinori 
Published: June 2015

AbstractA highly efficient majority‐rules effect of poly(quinoxaline‐2,3‐diyl)s (PQXs) bearing 2‐butoxymethyl chiral side chains at the 6‐ and 7‐positions was established and attributed to large ΔGh values (0.22–0.41 kJ mol−1), which are defined as the energy difference between P‐ and M‐helical conformations per chiral unit. A PQX copolymer prepared from a monomer derived from (R)‐2‐octanol (23 % ee) and a monomer bearing a PPh2 group adopted a single‐handed helical structure (>99 %) and could be used as a highly enantioselective chiral ligand in palladium‐catalyzed asymmetric reactions (products formed with up to 94 % ee), in which the enantioselectivity could be switched by solvent‐dependent inversion of the helical PQX backbone.
A pH‐Responsive MRI Agent that Can Be Activated Beyond the Tissue Magnetization Transfer Window
Authors: Wang Xiaojing , Wu Yunkou , Soesbe Todd C. , Yu Jing , Zhao Piyu , Kiefer Garry E. , Sherry A. Dean 
Published: June 2015

AbstractA terbium‐based complex that displays a water exchange CEST resonance well outside the normal magnetization transfer (MT) frequency range of tissues provides a direct readout of pH values by MRI. Deprotonation of the phenolic proton in this complex results in a frequency shift of 56 ppm in a bound water molecule exchange peak between pH 5 and 8. This allows direct imaging of pH without prior knowledge of the agent concentration and with essentially no interference from the tissue MT signal.
Reversal of a Single Base‐Pair Step Controls Guanine Photo‐Oxidation by an Intercalating Ruthenium(II) Dipyridophenazine Complex
Authors: Keane Páraic M. , Poynton Fergus E. , Hall James P. , Sazanovich Igor V. , Towrie Michael , Gunnlaugsson Thorfinnur , Quinn Susan J. , Cardin Christine J. , Kelly John M. 
Published: June 2015

AbstractSmall changes in DNA sequence can often have major biological effects. Here the rates and yields of guanine photo‐oxidation by Λ‐[Ru(TAP)2(dppz)]2+ have been compared in 5′‐{CCGGATCCGG}2 and 5′‐{CCGGTACCGG}2 using pico/nanosecond transient visible and time‐resolved IR (TRIR) spectroscopy. The inefficiency of electron transfer in the TA sequence is consistent with the 5′‐TA‐3′ versus 5′‐AT‐3′ binding preference predicted by X‐ray crystallography. The TRIR spectra also reveal the differences in binding sites in the two oligonucleotides.
CoOOH Nanosheets with High Mass Activity for Water Oxidation
Authors: Huang Junheng , Chen Junting , Yao Tao , He Jingfu , Jiang Shan , Sun Zhihu , Liu Qinghua , Cheng Weiren , Hu Fengchun , Jiang Yong , Pan Zhiyun , Wei Shiqiang 
Published: June 2015

AbstractEndowing transition‐metal oxide electrocatalysts with high water oxidation activity is greatly desired for production of clean and sustainable chemical fuels. Here, we present an atomically thin cobalt oxyhydroxide (γ‐CoOOH) nanosheet as an efficient electrocatalyst for water oxidation. The 1.4 nm thick γ‐CoOOH nanosheet electrocatalyst can effectively oxidize water with extraordinarily large mass activities of 66.6 A g−1, 20 times higher than that of γ‐CoOOH bulk and 2.4 times higher than that of the benchmarking IrO2 electrocatalyst. Experimental characterizations and first‐principles calculations provide solid evidence to the half‐metallic nature of the as‐prepared nanosheets with local structure distortion of the surface CoO6−x octahedron. This greatly enhances the electrophilicity of H2O and facilitates the interfacial electron transfer between Co ions and adsorbed ‐OOH species to form O2, resulting in the high electrocatalytic activity of layered CoOOH for water oxidation.
Strukturelle Aufklärung der Bispezifität von A‐Domänen als Basis für die Aktivierung nicht‐natürlicher Aminosäuren
Authors: Kaljunen Heidi , Schiefelbein Stephan H. H. , Stummer Daniela , Kozak Sandra , Meijers Rob , Christiansen Guntram , Rentmeister Andrea 
Published: June 2015

AbstractViele biologisch aktive, bakterielle Sekundärmetabolite werden durch modulare Enzymkomplexe, die sogenannten nicht‐ribosomalen Peptidsynthetasen, hergestellt. Die Substratauswahl erfolgt durch eine Adenylierungsdomäne (A‐Domäne), die die entsprechende Aminosäure mit hoher Selektivität aktiviert. Die kürzlich entdeckte A‐Domäne der Anabaenopeptin‐Synthetase aus Planktothrix agardhii (ApnA A1) ist in der Lage, zwei chemisch sehr unterschiedliche Aminosäuren (Arg und Tyr) umzusetzen. Wir zeigen hier anhand von Kristallstrukturen dieser A‐Domäne, wie sich diese beiden Substrate an die Bindungstasche des Enzyms anpassen. Die Analyse der Bindungstasche führte zur Identifizierung von drei Resten, die für die Substraterkennung essentiell sind. Durch systematischen Austausch dieser Reste konnten wir Enzymvarianten generieren, die monospezifisch waren oder Tryptophan spezifisch aktivierten. Die nicht‐natürliche Aminosäure 4‐Azidophenylalanin konnte ebenfalls effizient durch eine A‐Domänenvariante aktiviert werden, sodass die Produktion von diversifizierten nicht‐ribosomalen Peptiden für die bioorthogonale Markierung in greifbare Nähe rückt.
Synthesis and Intracellular Redox Cycling of Natural Quinones and Their Analogues and Identification of Indoleamine‐2,3‐dioxygenase (IDO) as Potential Target for Anticancer Activity
Authors: Blunt Christopher E. , Torcuk Canan , Liu Yang , Lewis William , Siegel David , Ross David , Moody Christopher J. 
Published: June 2015

AbstractNatural quinones, often linked with cellular oxidation processes, exhibit pronounced biological activity. In particular, the structurally unique isothiazolonaphthoquinone aulosirazole, isolated from blue‐green alga, possesses selective antitumor cytotoxicity, although its mechanism of action is unknown. The first synthesis of aulosirazole uses a route centered upon a late‐stage regioselective Diels–Alder reaction. The structurally related natural product pronqodine A, an inhibitor of prostaglandin release, and analogues thereof, were also prepared for comparison. Biological evaluation of the compounds identified one potential target as the immunoregulatory enzyme indoleamine‐2,3‐dioxygenase (IDO). The isothiazoloquinones are also efficient substrates for the human quinone reductase NQO1, and undergo intracellular NQO1‐dependent redox cycling resulting in the generation of reactive oxygen species, and at lower doses have the potential to alter the ratio of intracellular oxidized to reduced pyridine nucleotides.
Formation of the Δ18,19 Double Bond and Bis(spiroacetal) in Salinomycin Is Atypically Catalyzed by SlnM, a Methyltransferase‐like Enzyme
Authors: Jiang Chunyan , Qi Zhen , Kang Qianjin , Liu Jing , Jiang Ming , Bai Linquan 
Published: June 2015

AbstractSalinomycin is a widely used polyether coccidiostat and was recently found to have antitumor activities. However, the mechanism of its biosynthesis remained largely speculative until now. Reported herein is the identification of an unprecedented function of SlnM, homologous to O‐methyltransferases, by correlating its activity with the formation of the Δ18,19 double bond and bis(spiroacetal). Detailed in vivo and in vitro investigations revealed that SlnM, using positively charged S‐adenosylmethionine (SAM) or sinefungin as the cofactor, catalyzed the spirocyclization‐coupled dehydration of C19 in a highly atypical fashion to yield salinomycin.
Selective Michael Reaction Controlled by Supersilyl Protecting Group
Authors: Izumiseki Atsuto , Yamamoto Hisashi 
Published: June 2015

AbstractSelective Michael reaction of organolithium reagents to supersilyl methacrylate is reported. The method was able to control a single and double Michael addition. The successful termination of the process using the supersilyl protecting group allows for the controlled, chemoselective, and diastereoselective Michael reaction.
A Synthetic DNA‐Binding Domain Guides Distinct Chromatin‐Modifying Small Molecules to Activate an Identical Gene Network
Authors: Han Le , Pandian Ganesh N. , Chandran Anandhakumar , Sato Shinsuke , Taniguchi Junichi , Kashiwazaki Gengo , Sawatani Yoshito , Hashiya Kaori , Bando Toshikazu , Xu Yufang , Qian Xuhong , Sugiyama Hiroshi 
Published: June 2015

AbstractSynthetic dual‐function ligands targeting specific DNA sequences and histone‐modifying enzymes were applied to achieve regulatory control over multi‐gene networks in living cells. Unlike the broad array of targeting small molecules for histone deacetylases (HDACs), few modulators are known for histone acetyltransferases (HATs), which play a central role in transcriptional control. As a novel chemical approach to induce selective HAT‐regulated genes, we conjugated a DNA‐binding domain (DBD) “I” to N‐(4‐chloro‐3‐trifluoromethyl‐phenyl)‐2‐ethoxy‐benzamide (CTB), an artificial HAT activator. In vitro enzyme activity assays and microarray studies were used to demonstrate that distinct functional small molecules could be transformed to have identical bioactivity when conjugated with a targeting DBD. This proof‐of‐concept synthetic strategy validates the switchable functions of HDACs and HATs in gene regulation and provides a molecular basis for developing versatile bioactive ligands.
A Photoresponsive Smart Covalent Organic Framework
Authors: Huang Ning , Ding Xuesong , Kim Jangbae , Ihee Hyotcherl , Jiang Donglin 
Published: June 2015

AbstractOrdered π‐columnar structures found in covalent organic frameworks (COFs) render them attractive as smart materials. However, external‐stimuli‐responsive COFs have not been explored. Here we report the design and synthesis of a photoresponsive COF with anthracene units as the photoresponsive π‐building blocks. The COF is switchable upon photoirradiation to yield a concavo‐convex polygon skeleton through the interlayer [4π+4π] cycloaddition of anthracene units stacked in the π‐columns. This cycloaddition reaction is thermally reversible; heating resets the anthracene layers and regenerates the COF. These external‐stimuli‐induced structural transformations are accompanied by profound changes in properties, including gas adsorption, π‐electronic function, and luminescence. The results suggest that COFs are useful for designing smart porous materials with properties that are controllable by external stimuli.
Redox‐Controlled Exchange Bias in a Supramolecular Chain of Fe4 Single‐Molecule Magnets
Authors: Nava Andrea , Rigamonti Luca , Zangrando Ennio , Sessoli Roberta , Wernsdorfer Wolfgang , Cornia Andrea 
Published: June 2015

AbstractTetrairon(III) single‐molecule magnets [Fe4(pPy)2(dpm)6] (1) (H3pPy=2‐(hydroxymethyl)‐2‐(pyridin‐4‐yl)propane‐1,3‐diol, Hdpm=dipivaloylmethane) have been deliberately organized into supramolecular chains by reaction with RuIIRuII or RuIIRuIII paddlewheel complexes. The products [Fe4(pPy)2(dpm)6][Ru2(OAc)4](BF4)x with x=0 (2 a) or x=1 (2 b) differ in the electron count on the paramagnetic diruthenium bridges and display hysteresis loops of substantially different shape. Owing to their large easy‐plane anisotropy, the s=1 diruthenium(II,II) units in 2 a act as effective seff=0 spins and lead to negligible intrachain communication. By contrast, the mixed‐valent bridges (s=3/2, seff=1/2) in 2 b introduce a significant exchange bias, with concomitant enhancement of the remnant magnetization. Our results suggest the possibility to use electron transfer to tune intermolecular communication in redox‐responsive arrays of SMMs.
Coordination Assembly of Discoid Nanoparticles
Authors: Hirai Kenji , Yeom Bongjun , Chang Shu‐Hao , Chi Hang , Mansfield John F. , Lee Byeongdu , Lee Sungsik , Uher Ctirad , Kotov Nicholas A. 
Published: June 2015

AbstractSupramolecular chemistry utilizes coordination bonds to assemble molecular building blocks into a variety of sophisticated constructs. However, traditional coordination assemblies are based on organic compounds that have limited ability to transport charge. Herein, we describe coordination assembly of anisotropic FeS2 pyrite nanoparticles (NPs) that can facilitate charge transport. Zn2+ ions form supramolecular complexes with carboxylate end‐groups on NP surface, leading to multiparticle sheets with liquid‐crystal‐like organization. Conductivity and Hall carrier mobility of the p‐type layered semiconductor films with Zn2+ coordination bridging exceed those known for coordination compounds, some by several orders of magnitude. The nanoscale porosity of the assembled sheets combined with fast hole transport leads to high electrocatalytic activity of the NP films. The coordination assembly of NPs embraces the versatility of several types of building blocks and opens a new design space for self‐organized materials combining nanoscale and supramolecular structural motifs.
Hierarchical Nacre Mimetics with Synergistic Mechanical Properties by Control of Molecular Interactions in Self‐Healing Polymers
Authors: Zhu Baolei , Jasinski Nils , Benitez Alejandro , Noack Manuel , Park Daesung , Goldmann Anja S. , Barner‐Kowollik Christopher , Walther Andreas 
Published: June 2015

AbstractDesigning the reversible interactions of biopolymers remains a grand challenge for an integral mimicry of mechanically superior biological composites. Yet, they are the key to synergistic combinations of stiffness and toughness by providing sacrificial bonds with hidden length scales. To address this challenge, dynamic polymers were designed with low glass‐transition temperature Tg and bonded by quadruple hydrogen‐bonding motifs, and subsequently assembled with high‐aspect‐ratio synthetic nanoclays to generate nacre‐mimetic films. The high dynamics and self‐healing of the polymers render transparent films with a near‐perfectly aligned structure. Varying the polymer composition allows molecular control over the mechanical properties up to very stiff and very strong films (E≈45 GPa, σUTS≈270 MPa). Stable crack propagation and multiple toughening mechanisms occur in situations of balanced dynamics, enabling synergistic combinations of stiffness and toughness. Excellent gas barrier properties complement the multifunctional property profile.
Formation of Discrete Ladders and a Macroporous Xerogel Film by the Zipperlike Dimerization of Meso–Meso‐Linked Zinc(II) Porphyrin Arrays with Di(pyrid‐3‐yl)acetylene
Authors: Kose Kohei , Motoyanagi Jin , Kusukawa Takahiro , Osuka Atsuhiro , Tsuda Akihiko 
Published: June 2015

AbstractMetal porphyrins assemble to form a supramolecular architecture with a characteristic structure and characteristic properties and functions upon complexation with appropriate ligands. However, there are few applications of these assembly processes to the construction of polymeric porphyrin arrays with useful functionalities. In this study, we found that meso–meso‐linked ZnII porphyrin arrays underwent zipperlike dimerization upon complexation with di(pyrid‐3‐yl)acetylene (DPA) in chloroform to form discrete double‐stranded porphyrin ladders. Similarly, the assembly of poly(zinc(II) porphyrinylene) with DPA gave a thermoresponsive gel, whose three‐dimensional network structure was so strong that a macroporous xerogel film was obtained.
Identification of tert‐Butyl Cations in Zeolite H‐ZSM‐5: Evidence from NMR Spectroscopy and DFT Calculations
Authors: Dai Weili , Wang Chuanming , Yi Xianfeng , Zheng Anmin , Li Landong , Wu Guangjun , Guan Naijia , Xie Zaiku , Dyballa Michael , Hunger Michael 
Published: June 2015

AbstractExperimental evidence for the presence of tert‐butyl cations, which are important intermediates in acid‐catalyzed heterogeneous reactions, on solid acids has still not been provided to date. By combining density functional theory (DFT) calculations with 1H/13C magic‐angle‐spinning NMR spectroscopy, the tert‐butyl cation was successfully identified on zeolite H‐ZSM‐5 upon conversion of isobutene by capturing this intermediate with ammonia.
Selective Monoarylation of Primary Amines Using the Pd‐PEPPSI‐IPentCl Precatalyst
Authors: Sharif Sepideh , Rucker Richard P. , Chandrasoma Nalin , Mitchell David , Rodriguez Michael J. , Froese Robert D. J. , Organ Michael G. 
Published: June 2015

AbstractA single set of reaction conditions for the palladium‐catalyzed amination of a wide variety of (hetero)aryl halides using primary alkyl amines has been developed. By combining the exceptionally high reactivity of the Pd‐PEPPSI‐IPentCl catalyst (PEPPSI=pyridine enhanced precatalyst preparation, stabilization, and initiation) with the soluble and nonaggressive sodium salt of BHT (BHT=2,6‐di‐tert‐butyl‐hydroxytoluene), both six‐ and five‐membered (hetero)aryl halides undergo efficient and selective amination.
Octahedral and Cubic Gold Nanoframes with Platinum Framework
Authors: Ham Songyi , Jang Hee‐Jeong , Song Yookyung , Shuford Kevin L. , Park Sungho 
Published: June 2015

AbstractHerein, we report a general synthetic pathway to various shapes of three‐dimensional (3D) gold nanoframes (NFs) embedded with a Pt skeleton for structural rigidity. The synthetic route comprises three steps: site‐specific (edge and vertex) deposition of Pt, etching of inner Au, and regrowth of Au on the Pt framework. Site‐specific reduction of Pt on Au nanoparticles (NPs) led to the high‐quality of 3D Au NFs with good structural rigidity, which allowed the detailed characterization of the corresponding 3D metal NFs. The synthetic method described here will open new avenues toward many new kinds of 3D metal NFs.
Processing and properties of biodegradable compounds based on aliphatic polyesters
Authors: Nobile Maria Rossella , Cerruti Pierfrancesco , Malinconico Mario , Pantani Roberto 
Published: June 2015

ABSTRACTTwo aliphatic biodegradable polyesters, Poly(butylene succinate) and Poly(lactic acid), are selected together with two inorganic fillers, talc and TiO2, to obtain biodegradable compounds for replacing polystyrene in the production of disposable plastic cups and plates. The rheological behavior of the pure polymers and the compounds is investigated, the mechanical properties of the compounds are determined in terms of modulus and elongation at break, the heat distortion temperature of the compounds is measured and compared to those of pure PBS and PS. Finally, the biodegradation of the compounds is also investigated. The processability and the final properties, in terms of elastic modulus and heat distortion temperature, make these compounds interesting for the production of disposable plates and cups for hot food and beverages, also considering that the elongation at break is significant. Furthermore, the results of biodegradation tests in composting conditions show that the presence of TiO2 induces a lag time and lower values of biodegradation. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42481.
A Modest Proposal to Universalize the Insanity Defense and Replace Prisons and Punishment with Treatment and Education
Authors: Gilligan James 
Published: June 2015

AbstractThe insanity defense is based on the assumptions that with the exception of the insane, everyone possesses free will and the ability to distinguish right from wrong. These assumptions are incompatible with the deterministic premises on which psychoanalysis, psychology, psychiatry and all other behavioral and natural sciences are based, and with the epistemological premises on which all of the modern sciences are based. Criminal law is based on answering moral questions as to how evil a given defendant's mind was and how much punishment he deserves. But even if we could gain the knowledge we would need in order to answer those philosophic questions (which we cannot, since philosophy cannot produce knowledge), the answers would give us no help in answering the only questions that are relevant to the goal of reducing the incidence of violence and increasing the safety and well‐being of the people: namely, the empirical, scientific questions, “what are the causes of violence, and how can we prevent it?” The modern prison system was a well‐meaning experiment in social engineering that has failed, because it is based on fallacious assumptions. For example, we know by now that punishing people in order to achieve a moral goal, justice, does not prevent violence, it stimulates it. That is among the reasons that prisons need to be abolished and replaced with a new approach based on proven methods of preventing violence, namely, safe, secure, home‐like residential colleges and therapeutic communities. Copyright © 2015 John Wiley & Sons, Ltd.
History, Murder and the Fear of Death
Authors: Doctor Ronald 
Published: June 2015

AbstractThe account of the crime is nearly always a cover up story. Murder occurs concretely in most cases when it has been committed many times previously in daydreams, nightmares and sometimes in unconscious phantasy that has never become conscious. Before the deed, conscious efforts – sometimes unconscious ones, too – are designed and devoted to keeping the murder encapsulation from action. Then something takes place internally that breaks loose the murderousness from it's cordoned off status, so that the whole of the energies of the individual becomes devoted to enacting the murderous deed. In the death constellation there is a psychically traumatic and indigestible experience to do with death. Only with a life threatening trigger, displayed as the fear of death, did they enact their murderousness. Violence is thus a communication about the patient's belief systems about themselves, about their relationships with others and about their origins. Copyright © 2015 John Wiley & Sons, Ltd.