bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ethanol as a Hydrogenating Agent: Palladium‐Catalyzed Stereoselective Hydrogenation of Ynamides To Give Enamides
Authors: Siva Reddy Alla , Kumara Swamy K. C. 
Published: May 2017

AbstractEthanol is shown to act as a hydrogenating agent for ynamides under palladium catalysis. This behavior is different from the normally expected reaction of ethanol addition to alkynes. The reaction shows stereoselectivity for E enamides, which is in contrast to reports using other hydrogenating sources. The method was also extended to ynamines. Alternatively, the use of ethanol and ammonium formate as the hydrogenating source gives Z enamides. The role of ethanol in hydrogenation was demonstrated by means deuterium labeling experiment.
Self‐Assembly of Conjugated Metallopolymers with Tunable Length and Controlled Regiochemistry
Authors: Greenfield Jake L. , Rizzuto Felix J. , Goldberga Ieva , Nitschke Jonathan R. 
Published: May 2017

AbstractSelf‐assembled materials can be designed to express useful optoelectronic properties; however, achieving structural control is a necessary precondition for the optimization of desired properties. Here we report a simple, metal‐templated polymerization process that generates helical metallopolymer strands over 75 repeat units long (28 kDa) from a single bifunctional monomer and CuI. The resulting polymer consists of a double helix of two identical conjugated organic strands enclosing a central column of metal ions. The length of this metallopolymer can be controlled by adding monofunctional subcomponents to end‐cap the conjugated ligands. The use of ditopic and bulky monotopic subcomponents, respectively, allows a head‐to‐head or head‐to‐tail double helix to be generated. Spectroscopic measurements of different polymer lengths demonstrate how control over polymer length leads to control over the electronic and luminescent properties of the resulting material, thereby enabling tunable white‐light emission.
The Femtochemistry of a Ferracyclobutadiene
Authors: Wezisla Boris , Lindner Jörg , Das Ujjal , Filippou Alexander C. , Vöhringer Peter 
Published: May 2017

AbstractThe eminent role of metallacyclobutadienes as catalytic intermediates in organic synthesis and polymer chemistry is widely acknowledged. In contrast, their photochemistry is as yet entirely unexplored. Herein, the photo‐induced primary processes of a ferracyclobutadiene tricarbonyl complex in solution are revealed by femtosecond mid‐infrared spectroscopy. The time‐resolved vibrational spectra expose an ultrafast substitution of a basal CO ligand by a solvent molecule in a consecutive dissociation–association mechanism. Following optical excitation, the system relaxes non‐radiatively to the triplet ground state from which a CO is expelled. Since the triplet state is bound with respect to Fe−CO cleavage, the dissociation can only occur from vibrationally excited states. The excitation energy, vibrational relaxation, and intersystem crossing to the singlet ground state control the primary quantum yield for formation of the ferracyclic dicarbonyl–solvent product complex.
Triggering Redox Activity in a Thiophene Compound: Radical Stabilization and Coordination Chemistry
Authors: Curcio Massimiliano , Pankhurst James R. , Sproules Stephen , Mignard Dimitri , Love Jason B. 
Published: May 2017

AbstractThe synthesis, metalation, and redox properties of an acyclic bis(iminothienyl)methene L− are presented. This π‐conjugated anion displayed pronounced redox activity, undergoing facile one‐electron oxidation to the acyclic, metal‐free, neutral radical L. on reaction with FeBr2. In contrast, the reaction of L− with CuI formed the unique, neutral Cu2I2(L.) complex of a ligand‐centered radical, whereas reaction with the stronger oxidant AgBF4 formed the metal‐free radical dication L.2+.
Elusive Terminal Copper Arylnitrene Intermediates
Authors: Bakhoda Abolghasem (Gus) , Jiang Quan , Bertke Jeffery A. , Cundari Thomas R. , Warren Timothy H. 
Published: May 2017

AbstractWe report herein three new modes of reactivity between arylazides N3Ar with a bulky copper(I) β‐diketiminate. Addition of N3ArX3 (ArX3=2,4,6‐X3C6H2; X=Cl or Me) to [iPr2NN]Cu(NCMe) results in triazenido complexes from azide attack on the β‐diketiminato backbone. Reaction of [iPr2NN]Cu(NCMe) with bulkier azides N3Ar leads to terminal nitrenes [iPr2NN]Cu]=NAr that dimerize via formation of a C−C bond at the arylnitrene p‐position to give the dicopper(II) diketimide 4 (Ar=2,6‐iPr2C6H3) or undergo nitrile insertion to give diazametallocyclobutene 8 (Ar=4‐Ph‐2,6‐iPr2C6H2). Importantly, reactivity studies reveal both 4 and 8 to be “masked” forms of the terminal nitrenes [iPr2NN]Cu=NAr that undergo nitrene group transfer to PMe3, tBuNC, and even into a benzylic sp3 C−H bond of ethylbenzene.
Concise Total Synthesis of Dioncophylline E through an ortho‐Arylation Strategy
Authors: Toop Hamish D. , Brusnahan Jason S. , Morris Jonathan C. 
Published: May 2017

AbstractThe first total synthesis of the potent antimalarial 7,3′‐linked naphthylisoquinoline alkaloid dioncophylline E (1) has been completed. The synthesis proceeds in 12 steps (longest linear sequence) and in 15 % overall yield. Key transformations include an ortho‐arylation of a naphthol with an aryllead triacetate to construct the sterically hindered biaryl bond, and a three‐step sequence to stereoselectively generate the trans‐1,3‐dimethyl‐1,2,3,4‐tetrahydroisoquinoline moiety.
Near‐Infrared Photothermally Activated DNAzyme–Gold Nanoshells for Imaging Metal Ions in Living Cells
Authors: Wang Wenjing , Satyavolu Nitya Sai Reddy , Wu Zhenkun , Zhang Jian‐Rong , Zhu Jun‐Jie , Lu Yi 
Published: May 2017

AbstractDNAzymes have enjoyed success as metal ion sensors outside cells. Their susceptibility to metal‐dependent cleavage during delivery into cells has limited their intracellular applications. To overcome this limitation, a near‐infrared (NIR) photothermal activation method is presented for controlling DNAzyme activity in living cells. The system consists of a three‐stranded DNAzyme precursor (TSDP), the hybridization of which prevents the DNAzyme from being active. After conjugating the TSDP onto gold nanoshells and upon NIR illumination, the increased temperature dehybridizes the TSDP to release the active DNAzyme, which then carries out metal‐ion‐dependent cleavage, resulting in releasing the cleaved product containing a fluorophore. Using this construct, detecting Zn2+ in living HeLa cells is demonstrated. This method has expanded the DNAzyme versatility for detecting metal ions in biological systems under NIR light that exhibits lower phototoxicity and higher tissue penetration ability.
Total Synthesis of Rishirilide B by Organocatalytic Oxidative Kinetic Resolution: Revision of Absolute Configuration of (+)‐Rishirilide B
Authors: Odagi Minami , Furukori Kota , Takayama Kan , Noguchi Keiichi , Nagasawa Kazuo 
Published: May 2017

AbstractDescribed herein is the enantioselective syntheses of (+)‐ and (−)‐rishirilide B from the corresponding optically active β‐substituted tetralones, which were obtained by oxidative kinetic resolution based on α‐hydroxylation in the presence of a chiral guanidine‐bisurea bifunctional organocatalyst. Benzylic oxidation of the tetralones at C1 followed by regioselective isomerization of the oxabenzonorbornadiene structure led to rishirilide B. Our findings lead to the revision of the previously proposed (2R,3R,4R) absolute configuration of (+)‐rishirilide B to (2S,3S,4S).
Electrochemical Motion Tracking of Microorganisms Using a Large‐Scale‐Integration‐Based Amperometric Device
Authors: Ino Kosuke , Kanno Yusuke , Inoue Kumi Y. , Suda Atsushi , Kunikata Ryota , Matsudaira Masahki , Shiku Hitoshi , Matsue Tomokazu 
Published: May 2017

AbstractMotion tracking of microorganisms is useful to investigate the effects of chemical or physical stimulation on their biological functions. Herein, we describe a novel electrochemical imaging method for motion tracking of microorganisms using a large‐scale integration (LSI)‐based amperometric device. The device consists of 400 electrochemical sensors with a pitch of 250 μm. A convection flow caused by the motion of microorganisms supplies redox species to the sensors and increases their electrochemical responses. Thus, the flow is converted to electrochemical signals, enabling the electrochemical motion tracking of the microorganisms. As a proof of concept, capillary vibration was monitored. Finally, the method was applied to monitoring the motion of Daphnia magna. The motions of these microorganisms were clearly tracked based on the electrochemical oxidation of [Fe(CN)6]4− and reduction of O2.
Different Reactivity of As4towards Disilenes and Silylenes
Authors: Seitz Andreas E. , Eckhardt Maria , Sen Sakya S. , Erlebach Andreas , Peresypkina Eugenia V. , Roesky Herbert W. , Sierka Marek , Scheer Manfred 
Published: May 2017

AbstractThe activation of yellow arsenic is possible with the silylene [PhC(NtBu)2SiN(SiMe3)2] (1) and the disilene [(Me3Si)2N(η1‐Me5C5)Si=Si(η1‐Me5C5)N(SiMe3)2] (3). The reaction of As4with1leads to the unprecedented As10cage compound [(LSiN(SiMe3)2)3As10] (2; L=PhC(NtBu)2) with an As7nortricyclane core stabilized by arsasilene moieties containing silicon(II)bis(trimethylsilyl)amide substituents. In contrast, the compound [Cp*{(SiMe3)2N}SiAs]2(4) containing a butterfly‐like diarsadisilabicyclo[1.1.0]butane unit is formed by the reaction of As4with the disilene3. Both compounds were characterized by single‐crystal X‐ray diffraction analysis, NMR spectroscopy, and mass spectrometry. The reaction outcomes demonstrate the different reaction behavior of yellow arsenic (As4) compared to white phosphorus (P4) in the reactions with the corresponding silylenes and disilenes.
Small‐Molecule Inhibition of the UNC119–Cargo Interaction
Authors: Mejuch Tom , Garivet Guillaume , Hofer Walter , Kaiser Nadine , Fansa Eyad K. , Ehrt Christiane , Koch Oliver , Baumann Matthias , Ziegler Slava , Wittinghofer Alfred , Waldmann Herbert 
Published: May 2017

AbstractN‐Terminal myristoylation facilitates membrane binding and activity of proteins, in particular of Src family kinases, but the underlying mechanisms are only beginning to be understood. The chaperones UNC119A/B regulate the cellular distribution and signaling of N‐myristoylated proteins. Selective small‐molecule modulators of the UNC119–cargo interaction would be invaluable tools, but have not been reported yet. We herein report the development of the first UNC119–cargo interaction inhibitor, squarunkin A. Squarunkin A selectively inhibits the binding of a myristoylated peptide representing the N‐terminus of Src kinase to UNC119A with an IC50 value of 10 nm. It binds to UNC119 proteins in cell lysate and interferes with the activation of Src kinase. Our results demonstrate that small‐molecule inhibition of the UNC119–cargo interaction might provide new opportunities for modulating the activity of Src kinases that are independent of direct inhibition of the enzymatic kinase activity.
Insights Into How Heme Reduction Potentials Modulate Enzymatic Activities of a Myoglobin‐based Functional Oxidase
Authors: Bhagi‐Damodaran Ambika , Kahle Maximilian , Shi Yelu , Zhang Yong , Ädelroth Pia , Lu Yi 
Published: May 2017

AbstractHeme‐copper oxidase (HCO) is a class of respiratory enzymes that use a heme‐copper center to catalyze O2 reduction to H2O. While heme reduction potential (E°′) of different HCO types has been found to vary >500 mV, its impact on HCO activity remains poorly understood. Here, we use a set of myoglobin‐based functional HCO models to investigate the mechanism by which heme E°′ modulates oxidase activity. Rapid stopped‐flow kinetic measurements show that increasing heme E°′ by ca. 210 mV results in increases in electron transfer (ET) rates by 30‐fold, rate of O2 binding by 12‐fold, O2 dissociation by 35‐fold, while decreasing O2 affinity by 3‐fold. Theoretical calculations reveal that E°′ modulation has significant implications on electronic charge of both heme iron and O2, resulting in increased O2 dissociation and reduced O2 affinity at high E°′ values. Overall, this work suggests that fine‐tuning E°′ in HCOs and other heme enzymes can modulate their substrate affinity, ET rate and enzymatic activity.
Synthesis of Layered Carbonitrides from Biotic Molecules for Photoredox Transformations
Authors: Yang Can , Wang Bo , Zhang Linzhu , Yin Ling , Wang Xinchen 
Published: May 2017

AbstractThe construction of layered covalent carbon nitride polymers based on tri‐s‐triazine units has been achieved by using nucleobases (adenine, guanine, cytosine, thymine and uracil) and urea to establish a two‐dimensional semiconducting structure that allows band‐gap engineering applications. This biomolecule‐derived binary carbon nitride polymer enables the generation of energized charge carrier with light‐irradiation to induce photoredox reactions for stable hydrogen production and heterogeneous organosynthesis of C−O, C−C, C−N and N−N bonds, which may enrich discussion on chemical reactions in prebiotic conditions by taking account of the photoredox function of conjugated carbonitride semiconductors that have long been considered to be stable HCN‐derived organic macromolecules in space.
The Spider Orchid Caladenia crebra Produces Sulfurous Pheromone Mimics to Attract its Male Wasp Pollinator
Authors: Bohman Björn , Phillips Ryan D. , Flematti Gavin R. , Barrow Russell A. , Peakall Rod 
Published: May 2017

AbstractOne of the most intriguing natural observations is the pollination of orchids by sexual deception. Chemicals underpin this interaction between the orchid and its sexually attracted male insect pollinator, with the signaling compounds involved, called semiochemicals, predicted to mimic the chemical composition of the sex pheromone. We identified floral semiochemicals from Caladenia (spider orchids) for the first time. We further demonstrate that C. crebra attracts its single pollinator species with a unique system of (methylthio)phenols, three of which are new natural products. Furthermore, as predicted, the same compounds constitute the sex pheromone of the pollinator, the thynnine wasp Campylothynnus flavopictus, representing the first occurrence of sulfurous sex pheromones in Hymenoptera.
Phase diagram for the Na2O–PbO–H2O system at 130 °C
Authors: Liu Yan , Duan Dongping 
Published: May 2017

AbstractA phase diagram of the Na2O–PbO–H2O system at 130 °C was studied using Schreinemakers's method, to provide fundamental data for producing PbO via hydrometallurgical process. In the phase diagram, saturated solubility of PbO has two maximum values vs the sodium hydroxide concentration in the solution. The equilibrium solid phases of lead oxide (PbO), sodium plumbite hydroxide (Na2O·PbO·H2O) and sodium hydroxide (NaOH) were identified in the different alkali concentration regions, which is different from that at low temperature presented in literature. Copyright © 2017 Curtin University of Technology and John Wiley & Sons, Ltd.
Simultaneous removal of Cd, Co, Cu, Mn, Ni, and Zn from synthetic solutions on a hemp‐based felt. II. Chemical modification
Authors: Loiacono Sonia , Crini Grégorio , Martel Bernard , Chanet Gilles , Cosentino Cesare , Raschetti Marina , Placet Vincent , Torri Giangiacomo , Morin‐Crini Nadia 
Published: May 2017

ABSTRACTIn this study, we propose a chemical pretreatment to improve the performance of a hemp‐based material in felt form used as an adsorbent for removing the metals from aqueous mixtures of Cd, Co, Cu, Mn, Ni, and Zn. The felt was coated with a maltodextrin‐1,2,3,4‐butane tetracarboxylic polymer in order to provide ion‐exchange properties to the material by introducing carboxylic groups. It was characterized by solid‐state 13C‐NMR technique and by energy‐dispersive X‐ray spectroscopy. This new adsorbent was then used in batch experiments and its performances were compared with those of non‐modified hemp. Different controlling experimental conditions have been investigated. Modified hemp exhibited strong adsorption capacities due to a chemisorption mechanism (complexation, ion exchange): up to 25 mg/L (in reality, 150 mg of metals per L), all metals in the solution were removed. A modified hemp dosage of 1 g was able to remove 13.91 mg of metals in 100 mL of solution at a concentration of 25 mg/L for each metal, whereas nonmodified hemp only removed 7.4 mg in the same experimental conditions. Adsorption of metals reached equilibrium in 60 min and the performances were pH‐independent between 3 and 6, but dependent on the presence of NaCl, except for Cu. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45138.
Preparation of a novel poly(ether sulfone) adsorptive ultrafiltration membrane containing a crosslinked quaternary chitosan salt and chromate removal
Authors: Huang Zheng‐Qing , Yang Tian‐Qi , Zhou Kai‐Mei , Chen Jun‐Ping , Wei Peng , Zhang Zhi , Xu Hong‐Tao 
Published: May 2017

ABSTRACTTo improve the removal performance of low‐concentration hexavalent chromium [Cr(VI)] in the ultrafiltration (UF) process, adsorptive UF membranes were prepared from suspensions consisting of poly(ether sulfone), N,N‐dimethylacetamide, poly(vinyl pyrrolidone), and crosslinked quaternary chitosan salt (CQS). The results show that the contact angle of the membrane increased from 67 to 83° when the content of CQS was changed from 0 to 10 wt %. Meanwhile, the initial rejection of bovine serum albumin decreased from 90 to 61%, and the pure water fluxes of the membranes showed no obvious change. The rejection of Cr(VI) increased from 20% to 87% when the content of CQS was changed from 0 to 10 wt % in the membrane. Adsorptive UF membranes could be generated by a 1 mol/L solution of NaCl. The adsorption data were more applicable for a pseudo‐second‐order kinetic model and the Langmuir isotherm model. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45198.
Haploinsufficiency of NADPH Oxidase Subunit Neutrophil Cytosolic Factor 2 Is Sufficient to Accelerate Full‐Blown Lupus in NZM 2328 Mice
Authors: Jacob Chaim O. , Yu Ning , Yoo Dae‐Goon , Perez‐Zapata Lizet J. , Barbu Emilia Alina , Kaplan Mariana J. , Purmalek Monica , Pingel Jeanette T. , Idol Rachel A. , Dinauer Mary C. 
Published: May 2017

ObjectiveWe have previously established that the gene for neutrophil cytosolic factor 2 (NCF‐2) predisposes to lupus, and we have identified lupus patients with point mutations that are predicted to cause reduced NADPH oxidase activity. We undertook this study to investigate the relationship between reduced leukocyte NADPH oxidase activity and immune dysregulation associated with systemic lupus erythematosus (SLE).MethodsWe generated NCF‐2–null mice, in which NADPH oxidase activity is absent, on the nonautoimmune C57BL/6 (B6) mouse background and on the NZM 2328 mouse background, a polygenic model in which mice spontaneously develop lupus. Clinical disease, serology, and immunopathology were evaluated.ResultsNCF‐2–null mice on the B6 background were susceptible to Aspergillus fumigatus pneumonia characteristic of chronic granulomatous disease, but did not develop systemic lupus disease. In contrast, NCF‐2–null and even NCF‐2–haploinsufficient mice on the NZM 2328 background developed accelerated full‐blown lupus with significantly accelerated lupus kidney disease. This was characterized by more rapid development of hyperactive B cell and T cell immune compartments, increased expression of type I interferon–responsive genes, and generation of neutrophil extracellular traps, which were observed even in the absence of NADPH oxidase activity.ConclusionJust as patients with chronic granulomatous disease who lack NADPH oxidase rarely develop SLE, NCF‐2–null mice on a nonautoimmune background were susceptible to a chronic granulomatous disease–like opportunistic infection but did not develop lupus. In contrast, on a lupus‐prone background, even haploinsufficiency of NCF‐2 accelerated the development of full‐blown lupus disease. This establishes an interaction between reduced oxidase activity and other lupus‐predisposing genes, paralleling human SLE–associated variants predicted to have only reduced NADPH oxidase activity.
Robot kinematics made easy using RoboAnalyzer software
Authors: Othayoth Ratan S. , Chittawadigi Rajeevlochana G. , Joshi Ravi P. , Saha Subir K. 
Published: May 2017

AbstractRoboAnalyzer is a software based on 3D model of robots. It was developed primarily for teaching and learning of robot mechanics, although it is robust enough for the use by researchers as well. The motive behind the development of RoboAnalyzer was mainly to help teachers and students get started with teaching/learning of robotics using template‐based skeleton models or CAD models of serial robots. This minimizes the time otherwise spent on modeling, programming, and simulating the robots from scratch. In this article, we focus on the visualization of the Denavit Hartenberg (DH) parameters used to define a robot's architecture, and the modeling of the robot's input‐output motion characteristics, that is, robot kinematics, using them. The advantages of using RoboAnalyzer to overcome several challenges of learning robotics in a classroom environment are also discussed.
“To serve and protect” when expecting to be seen negatively: The relation between police officers' contact with citizens, meta‐stereotyping, and work‐related well‐being
Authors: Gordijn Ernestine H. , Vacher Loreline , Kuppens Toon 
Published: May 2017

AbstractWe examined the relationship between contact of police officers with citizens, their (meta‐)stereotypes about citizens, and their work‐related well‐being. Ninety‐three police officers from 4 police stations in low‐ and high‐crime regions in France completed the questionnaire. As expected, negative well‐being of police officers is predicted by negative contact with citizens and their belief that police officers are stereotyped negatively by citizens. Moreover, the relationship between negative contact and negative well‐being was mediated by police officers' beliefs that police officers are perceived negatively by citizens, whereas their perceptions of citizens did not mediate this relationship. Interestingly, level of crime did not influence these relationships. Together, this research shows the important role of beliefs about how one's group is stereotyped when in contact with another group as it may have consequences for people's well‐being.
Selective Covalent Protein Modification by 4‐Halopyridines through Catalysis
Authors: Schardon Christopher L. , Tuley Alfred , Er Joyce A. V. , Swartzel Jake C. , Fast Walter 
Published: May 2017

AbstractWe have investigated 4‐halopyridines as selective, tunable, and switchable covalent protein modifiers for use in the development of chemical probes. Nonenzymatic reactivity of 4‐chloropyridine with amino acids and thiols was ranked with respect to common covalent protein‐modifying reagents and found to have reactivity similar to that of acrylamide, but could be switched to a reactivity similar to that of iodoacetamide upon stabilization of the positively charged pyridinium. Diverse, fragment‐sized 4‐halopyridines inactivated human dimethylarginine dimethylaminohydrolase‐1 (DDAH1) through covalent modification of the active site cysteine, acting as quiescent affinity labels that required off‐pathway catalysis through stabilization of the protonated pyridinium by a neighboring aspartate residue. A series of 2‐fluoromethyl‐substituted 4‐chloropyridines demonstrated that the pKa and kinact/KI values could be predictably varied over several orders of magnitude. Covalent labeling of proteins in an Escherichia coli lysate was shown to require folded proteins, indicating that alternative proteins can be targeted, and modification is likely to be catalysisdependent. 4‐Halopyridines, and quiescent affinity labels in general, represent an attractive strategy to develop reagents with switchable electrophilicity as selective covalent protein modifiers.