bluuebunny/crossref_metadata_2025 huggingface dataset:
A Cake‐Style CoS2@MoS2/RGO Hybrid Catalyst for Efficient Hydrogen Evolution
Authors: Guo Yaxiao , Gan Linfeng , Shang Changshuai , Wang Erkang , Wang Jin
Published: December 2016

A three‐tiered cake‐style composite is elaborately established, with the characteristic of a double‐deck of MoS2 nanosheets and reduction of graphene oxide (RGO) sheets dotted with CoS2 nanoparticles (CoS2@MoS2/RGO). Because of the prominent synergistic effect of graphene acting as conductive support, MoS2 and CoS2 providing abundant catalytically active sites, and the cake‐style structure promoting mechanical stability, the CoS2@MoS2/RGO exhibits a superior hydrogen evolution reaction activity with a small overpotential of 98 mV at cathodic current density of 10 mA cm−2, and a small Tafel slope of 37.4 mV dec−1, as well as excellent cycling stability. Density functional theory calculations reveal that the hydrogen adsorption free energy of CoS2@MoS2/RGO is close to zero.
A Polymetallic Metal‐Organic Framework‐Derived Strategy toward Synergistically Multidoped Metal Oxide Electrodes with Ultralong Cycle Life and High Volumetric Capacity
Authors: Niu Shanshan , Wang Zhiyu , Zhou Tao , Yu Mingliang , Yu Mengzhou , Qiu Jieshan
Published: December 2016

Metal‐organic frameworks (MOFs) are very convenient self‐templated precursors toward functional materials with tunable functionalities. Although a huge family of MOFs has been discovered, conventional MOF‐derived strategies are largely limited to the sole MOF source based on a handful of the metal elements. The limitation in structure and functionalities greatly restrains the maximum performance of MOF‐based materials for fulfilling the practical potential. This study reports a polymetallic MOF‐derived strategy for easy synthesis of metal‐oxide‐based nanohybrids with precisely tailored multicomponent active dopants. A variety of MoO2‐based nanohybrids with synergistical co‐doping of W, Cu, and P are yielded by controlled pyrolysis of tailor‐made polymetallic MOFs. The W doping induces the formation of MoxW1−xO2 solid solution with better activity. The homogeneous dispersion of Cu nanocrystallites in robust P‐doped carbon skeleton creates a conductive network for fast charge transfer. Boosting by synergistically multidoping effect, the Mo0.8W0.2O2‐Cu@P‐doped carbon nanohybrids with optimized composition exhibit exceptionally long cycle life of 2000 cycles with high capacities but very slow capacity loss (0.043% per cycle), as well as high power output for lithium storage. Remarkably, the co‐doping of heavy W and Cu elements in MoO2 with high density makes them particularly suitable for high volumetric lithium storage.
Solvent‐Based Soft‐Patterning of Graphene Lateral Heterostructures for Broadband High‐Speed Metal–Semiconductor–Metal Photodetectors
Authors: Xu Yang , Ali Ayaz , Shehzad Khurram , Meng Nan , Xu Mingsheng , Zhang Yuhan , Wang Xinran , Jin Chuanhong , Wang Hongtao , Guo Yuzheng , Yang Zongyin , Yu Bin , Liu Yuan , He Qiyuan , Duan Xiangfeng , Wang Xiaomu , Tan Ping‐Heng , Hu Weida , Lu Hai , Hasan Tawfique
Published: December 2016

Solvents are essential in synthesis, transfer, and device fabrication of 2D materials and their functionalized forms. Controllable tuning of the structure and properties of these materials using common solvents can pave new and exciting pathways to fabricate high‐performance devices. However, this is yet to be materialized as solvent effects on 2D materials are far from well understood. Using fluorine functionalized chemical vapor deposited graphene (FG) as an example, and in contrast to traditional “hard‐patterning” method of plasma etching, the authors demonstrate a solvent‐based “soft‐patterning” strategy to enable its selective defluorination for the fabrication of graphene‐FG lateral heterostructures with resolution down to 50 nm. In this strategy, the oxygen plasma etching process of patterning after graphene transfer is avoided and high quality surfaces are preserved through a physically continuous atomically thin sheet, which is critical for high performance photodetection, especially in the high‐speed domain. The fabricated lateral graphene heterostructures are further employed to demonstrate a high speed metal–semiconductor–metal photodetector (<10 ns response time), with a broadband response from deep‐UV (200 nm) to near‐infrared (1100 nm) range. Thanks to the high quality surface with much less defects due to the “soft‐patterning” strategy, the authors achieve a high deep‐UV region photoresponsivity as well as the ultrafast time response. The strategy offers a unique and scalable method to realize continuous 2D lateral heterostructures and underscores the significance of inspiring future designs for high speed optoelectronic devices.
Total Synthesis of (±)‐Dihydroisosubamol
Authors: Pflästerer Daniel , Rudolph Matthias , Yates Brian F. , Ariafard Alireza , Hashmi A. Stephen K.
Published: December 2016

We herein report the first total synthesis of the dibenzocycloheptanoide (±)‐dihydroisosubamol. The key step includes a recently developed gold‐catalysed hydroarylation reaction for the construction of the dibenzocycloheptene motif. Additional steps are a Suzuki‐Miyaura cross coupling, a palladium‐catalysed hydroxylation and an allylic oxidation. To access the saturated seven‐membered ring system an iridium‐catalysed hydrogenation proved to be successful.

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Full‐physics simulations of spray‐particle interaction in a bubbling fluidized bed
Authors: Askarishahi Maryam , Salehi Mohammad‐Sadegh , Radl Stefan
Published: December 2016

Numerical simulations of a gas‐particle‐droplet system were performed using an Euler‐Lagrange approach. Models accounting for (1) the interaction between droplets and particles, (2) evaporation from the droplet spray, as well as (3) evaporation of liquid from the surface of non‐porous particles were considered. The implemented models were verified for a packed bed, as well as other standard flow configurations. The developed models were then applied for the simulation of flow, as well as heat and mass transfer in a fluidized bed with droplet injection. The relative importance of droplet evaporation vs. evaporation from the particle surface was quantified. It was proved that spray evaporation competes with droplet deposition and evaporation from the particle surface. Moreover, we show that adopting a suitable surface coverage model is vital when attempting to make accurate predictions of the particle's liquid content. © 2017 American Institute of Chemical Engineers AIChE J, 63: 2569–2587, 2017
Can Housing and Service Interventions Reduce Family Separations for Families Who Experience Homelessness?
Authors: Shinn Marybeth , Brown Scott R. , Gubits Daniel
Published: December 2016

Family break‐up is common in families experiencing homelessness. This paper examines the extent of separations of children from parents and of partners from each other and whether housing and service interventions reduced separations and their precursors among 1,857 families across 12 sites who participated in the Family Options Study. Families in shelters were randomized to offers of one of three interventions: permanent housing subsidies that reduce expenditures for rent to 30% of families’ income, temporary rapid re‐housing subsidies with some services directed at housing and employment, and transitional housing in supervised facilities with extensive psychosocial services. Each group was compared to usual care families who were eligible for that intervention but received no special offer. Twenty months later, permanent housing subsidies almost halved rates of child separation and more than halved rates of foster care placements; the other interventions did not affect separations significantly. Predictors of separation were primarily homelessness and drug abuse (all comparisons), and alcohol dependence (one comparison). Although housing subsidies reduced homelessness, alcohol dependence, intimate partner violence, and economic stressors, the last three variables had no association with child separations in the subsidy comparison; thus subsidies had indirect effects via reductions in homelessness. No intervention reduced partner separations.
Natural selection and type 2 diabetes‐associated mortality in an isolated indigenous community in the valley of Oaxaca, southern Mexico
Authors: Little Bertis B. , Peña Reyes Maria Eugenia , Malina Robert M.
Published: December 2016

Objective

This study tests the hypothesis that natural selection is associated with type 2 diabetes (T2D)‐associated mortality and fertility in a rural isolated Zapotec community in the Valley of Oaxaca, southern Mexico.

Participants and Methods

Mortality data and related demographic and genealogic information were linked with data for fertility, prereproductive mortality and family history of mortality attributed to T2D. Physician verified T2D mortality (n = 27) between 1980 and 2009 and imputed T2D (n = 70) from cardiovascular mortality (68% random sample) and renal failure (44% random sample). Bootstrapping was used to obtain a robust variance estimate in survival analysis and multivariate analysis of variance.

Results

Estimated maximum natural selection by Crow's Index occurred circa 1930 and was relaxed after this time in the study population. Cox‐regression survival analysis of T2D mortality with covariates (family history of T2D, cardiovascular disease, renal failure) indicated a significant hazard ratio (HR = 5.95, 95% CI: 1.38–25.67, p < .008) for the increase in T2D in 2000 to 2009. Survival analysis of imputed T2D resulted in a significant HR of 2.03 (95% CI: 1.08–3.85, p = .01) for the increase in T2D in the 2000 to 2009 cohort (reference group: 1980–1989). Mean number of live born offspring was lower among T2D (n = 27, 4.04 ± 3.85 SD) compared to non‐T2D (n = 199, 5.30 ± 3.48) groups (p < .08). Mean number of live born offspring was lower (p = .003) among imputed T2D compared to non‐T2D groups (4.10 ± 3.44 vs. 5.62 + 3.50).

Discussion

T2D‐associated mortality increased in frequency as natural selection decreased, and favored offspring survival of non‐T2D descedants. The results indicated statistically significant directional selection against T2D and imputed T2D to this population isolate.
Dynamic mechanical analysis of ethylene/1‐hexene copolymers: The effect of the catalyst type on the short‐chain branching distribution and properties of the amorphous and crystalline phases
Authors: Shundrina Inna K. , Matsko Mikhail A. , Baskakova Kseniya I. , Echevskaya Ludmila G. , Nikolaeva Marina I. , Shundrin Leonid A. , Zakharov Vladimir A.
Published: December 2016

Dynamic mechanical analysis was used to study ethylene/1‐hexene copolymers with different compositions, molecular weight distributions, and profiles of short‐chain branching (SCB) versus molecular weight. These copolymers were produced over a highly active supported titanium–magnesium catalyst (TMC), a highly active supported vanadium–magnesium catalysts (VMC), and a supported zirconocene catalyst. A higher fraction of the crystalline phase in the copolymers prepared with VMC was shown to result in higher elastic modulus values. β relaxation was found to be sensitive to the SCB distribution versus the molecular weight. The copolymers prepared with the zirconocene catalyst and VMC were characterized by more uniform SCB distributions and higher temperatures of β relaxation compared to the copolymers prepared with TMC. The mobility of the polymer chains at room temperature in the amorphous phase obtained by the spin‐probe method rose with increasing branch content in the copolymers and was not sensitive to different SCB distribution profiles. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44638.
Implementation and modification of an anatomy‐based integrated curriculum
Authors: Klement Brenda J. , Paulsen Douglas F. , Wineski Lawrence E.
Published: December 2016

Morehouse School of Medicine elected to restructure its first‐year medical curriculum by transitioning from a discipline‐based to an integrated program. The anatomy course, with regional dissection at its core, served as the backbone for this integration by weaving the content from prior traditional courses into the curriculum around the anatomy topics. There were four primary goals for this restructuring process. Goal 1: develop new integrated courses. Course boundaries were established at locations where logical breaks in anatomy content occurred. Four new courses were created, each containing integrated subject content. Goal 2: establish a curriculum management team. The team consisted of course directors, subject specialists, and a curriculum director. This team worked together to efficiently manage the new curriculum. Goal 3: launch contemporary examination and question banking methods. An electronic system, in which images could be included, was implemented for examinations and quizzes, and for storing and refining questions. Goal 4: ensure equitable distribution of standardized examinations and course grading systems among all courses. Assessments included quizzes, in‐course examinations, and National Board of Medical Examiners® (NBME®) Subject Examinations. A standard plan assigned the contribution of each to the final course grade. Significant improvement was seen on subject examinations. Once the obstacles and challenges of integration were overcome, a robust and efficient education program was developed. The curriculum is expected to continue evolving and improving, while retaining full regional dissection as a core element. Anat Sci Educ 10: 262–275. © 2016 American Association of Anatomists.
Facet‐Dependent Electrical Conductivity Properties of Silver Oxide Crystals
Authors: Tan Chih‐Shan , Chen Ying‐Jui , Hsia Chi‐Fu , Huang Michael H.
Published: December 2016

Ag2O cubes, truncated octahedra, rhombic dodecahedra, and rhombicuboctahedra were synthesized in aqueous solution. Two tungsten probes were brought into contact with a single particle for electrical conductivity measurements. Strongly facet‐dependent electrical conductivity behaviors have been observed. The {111} faces are most conductive. The {100} faces are moderately conductive. The {110} faces are nearly non‐conductive. When electrodes contacted two different facets of a rhombicuboctahedron, asymmetrical I–V curves were obtained. The {111} and {110} combination gives the best I–V curve expected for a p‐n junction with current flowing in one direction through the crystal but not in the opposite direction. Density of states (DOS) plots for varying number of different lattice planes of Ag2O match with the experimental results, suggesting that the {111} faces are most electrically conductive. The thicknesses of the thin surface layer responsible for the facet‐dependent properties of Ag2O crystals have been determined.
Theoretical evidence of maximum intracellular currents versus frequency in an Escherichia coli cell submitted to AC voltage
Authors: Xavier Pascal , Rauly Dominique , Chamberod Eric , Martins Jean M.F.
Published: December 2016

In this work, the problem of intracellular currents in longilinear bacteria, such as Escherichia coli, suspended in a physiological medium and submitted to a harmonic voltage (AC), is analyzed using the Finite‐Element‐based software COMSOL Multiphysics. Bacterium was modeled as a cylindrical capsule, ended by semi‐spheres and surrounded by a dielectric cell wall. An equivalent single‐layer cell wall was defined, starting from the well‐recognized three‐shell modeling approach. The bacterium was considered immersed in a physiological medium, which was also taken into account in the modeling. A new complex transconductance was thus introduced, relating the complex ratio between current inside the bacterium and voltage applied between two parallel equipotential planes, separated by a realistic distance. When voltage was applied longitudinally relative to the bacterium main axis, numerical results in terms of frequency response in the 1–20 MHz range for E. coli cells revealed that transconductance magnitude exhibited a maximum at a frequency depending on the cell wall capacitance. This occurred in spite of the purely passive character of the model and could be explained by an equivalent electrical network giving very similar results and showing special conditions for lateral paths of the currents through the cell wall. It is shown that the main contribution to this behavior is due to the conductive part of the current. Bioelectromagnetics. 38:213–219, 2017. © 2016 Wiley Periodicals, Inc.
Indole: An evolutionarily conserved influencer of behavior across kingdoms
Authors: Tomberlin Jeffery K. , Crippen Tawni L. , Wu Guoyao , Griffin Ashleigh S. , Wood Thomas K. , Kilner Rebecca M.
Published: December 2016

Indole is a key environmental cue that is used by many organisms. Based on its biochemistry, we suggest indole is used so universally, and by such different organisms, because it derives from the metabolism of tryptophan, a resource essential for many species yet rare in nature. These properties make it a valuable, environmental cue for resources almost universally important for promoting fitness. We then describe how indole is used to coordinate actions within organisms, to influence the behavior of conspecifics and can even be used to change the behavior of species that belong to other kingdoms. Drawing on the evolutionary framework that has been developed for understanding animal communication, we show how this is diversely achieved by indole acting as a cue, a manipulative signal, and an honest signal, as well as how indole can be used synergistically to amplify information conveyed by other molecules. Clarifying these distinct functions of indole identifies patterns that transcend different kingdoms of organisms.
Reassigning stop codons via translation termination: How a few eukaryotes broke the dogma
Authors: Alkalaeva Elena , Mikhailova Tatiana
Published: December 2016

The genetic code determines how amino acids are encoded within mRNA. It is universal among the vast majority of organisms, although several exceptions are known. Variant genetic codes are found in ciliates, mitochondria, and numerous other organisms. All revealed genetic codes (standard and variant) have at least one codon encoding a translation stop signal. However, recently two new genetic codes with a reassignment of all three stop codons were revealed in studies examining the protozoa transcriptomes. Here, we discuss this finding and the recent studies of variant genetic codes in eukaryotes. We consider the possible molecular mechanisms allowing the use of certain codons as sense and stop signals simultaneously. The results obtained by studying these amazing organisms represent a new and exciting insight into the mechanism of stop codon decoding in eukaryotes. Also see the video abstract here.
Temperature‐dependent molecular dynamics study reveals an ionic liquid induced 310‐ to α‐helical switch in a neurotoxin
Authors: Sajeevan Karuna Anna , Roy Durba
Published: December 2016

Thermal melting and recooling of AuIB, a neurotoxic conopeptide and a highly potent nonaddictive pain reliever is investigated thoroughly in water and an ionic liquid (IL) 1‐butyl‐3‐methylimidazolium Chloride, [Im41][Cl] by classical molecular dynamics simulations. Structural evolution of AuIB in water and the IL is observed at different temperatures between 305 and 400 K, to explore how highly viscous ionic solvents affect the peptide structure as compared to conventional solvent water. At 305 K, unlike water, the coercive effect of IL frustrates AuIB secondary structural motifs significantly. As the temperature is raised, a very interesting IL induced conformational transition from 310‐ to α‐helix is noticed in the peptide, presumably triggered by a significant restructuring of the peptide H‐bond network. The backbone length distributions of the peptide indicate that the IL induced conformational switching is accompanied by a reduction of the axial rise of the helical region, encompassing the residues Pro‐6 to Ala‐10. Further, we estimated the void space available to the peptide for its structural relaxation within the first solvation shell of ∼5 Å in water as well as in IL. A temperature increase by 100 K, opens up an estimated void volume of ∼70 Å3, equivalent to the volume of approximately six water molecules, around the peptide in IL. Cooling simulations of AuIB point to the crucial interplay between thermodynamically favored AuIB conformers and their kinetic control. This study provides a comprehensive understanding of the ionic solvation of biomolecules reinforcing previous experimental findings.
Single‐step purification of cyclotides using affinity chromatography
Authors: Uddin Shaikh Jamal , Muhammad Taj , Shafiullah Md , Slazak Blazej , Rouf Razina , Göransson Ulf
Published: December 2016

Cyclotides are considered promising scaffolds for drug development owing to their inherent host defence activities and highly stable structure, defined by the cyclic cystine knot. These proteins are expressed as complex mixtures in plants. Although several methods have been developed for their isolation and analysis, purification of cyclotides is still a lengthy process. Here, we describe the use of affinity chromatography for the purification of cyclotides using polyclonal IgG antibodies raised in rabbits against cycloviolacin O2 and immobilized on NHS‐activated Sepharose columns. Cycloviolacin O2 was used as a model substance to evaluate the chromatographic principle, first as a pure compound and then in combination with other cyclotides, that is, bracelet cyclotide cycloviolacin O19 and Möbius cyclotide kalata B1, and in a plant extract. We demonstrate that single‐step purification of cyclotides by affinity chromatography is possible but cross reactivity may occur between homologue cyclotides of the bracelet subfamily.
Metabolic profiles revealed synergistically antidepressant effects of lilies and Rhizoma Anemarrhenae in a rat model of depression
Authors: Du Hongli , Zhao Hongxia , Lai Xueli , Lin Qishan , Zhu Zhenyu , Chai Yifeng , Lou Ziyang
Published: December 2016

Depression is a major cause of illness and disability. We applied untargeted metabolomics using mass spectrometry to identify metabolic signatures associated with depression in serum and explored the antidepressant effects of lilies and Rhizoma Anemarrhenae on an experimental model of chronic unpredictable mild stress (CUMS). Meanwhile metabolomics based on UHPLC‐Q‐TOF‐MS was used to study the change in metabolites in CUMS rat serum and to evaluate the effects of Rhizoma Anemarrhenae and lilies (alone and in combination). Partial least squares‐discriminant analysis identified 30 metabolites as decisive marker compounds that discriminated the CUMS rats and the control rats. The majority of these metabolites were involved in amino acid metabolism, the tricarboxylic acid cycle, and phosphoglyceride metabolism. The reliability of the metabolites was evaluated by the administration of lilies, Rhizoma Anemarrhenae, fluoxetine and the combination of lilies and Rhizoma Anemarrhenae to the CUMS rats. Behavior studies demonstrated that treatment with the combination of lilies and Rhizoma Anemarrhenae resulted in optimal antidepressant effects. The combination treatment was almost as effective as fluoxetine. Our results suggest that lilies and Rhizoma Anemarrhenae demonstrate synergistically antidepressant effects in CUMS via the regulation of multiple metabolic pathways. These findings provide insight into the pathophysiological mechanisms underlying CUMS and suggest innovative and effective treatments for this disorder.
Rapid determination of oxindole alkaloids in cat's claw by HPLC using ionic liquid‐based microwave‐assisted extraction and silica monolithic column
Authors: Chang Chih‐Wei , Yeh Yu‐Ying , Chang Li‐Ching , Hsu Mei‐Chich , Wu Yu‐Tse
Published: December 2016

Cat's claw is a large woody vine with hook‐like thorns, and has been traditionally used to treat inflammatory disorders in South and Central America. In this study, a rapid, validated high‐performance liquid chromatographic (HPLC) method using a silica monolithic column was developed for the simultaneous determination of oxindole alkaloids, namely rhynchophylline, pteropodine, isomitraphylline and isopteropodine, in cat's claw. The ionic liquid‐based microwave‐assisted extraction (ILMAE), considered as an environmentally friendly and powerful tool, was first applied in the extraction of oxindole alkaloids. To optimize the HPLC method, the stationary phases, pH values of mobile phase and flow rates were investigated. The validated HPLC method using a Monolithic RP18e column (100 × 4.6 mm) enables these analytes to be separated almost twice as fast as with a conventional particulate column (~16 vs ~30 min) with limits of quantification and detection of 0.5 and 0.15 μg/mL, respectively. The ILMAE conditions were optimized by the Taguchi orthogonal array design. In comparison with conventional water boiling extraction, ILMAE offers almost four times higher yields within an extremely short extraction time. The developed HPLC coupled with ILMAE method could be efficient and practical for rapid determination of oxindole alkaloids in cat's claw.
Cortical interactions during the resolution of information processing demands in autism spectrum disorders
Authors: Denisova Kristina , Zhao Guihu , Wang Zhishun , Goh Suzanne , Huo Yuankai , Peterson Bradley S.
Published: December 2016

Introduction

Our flexible and adaptive interactions with the environment are guided by our individual representation of the physical world, estimated through sensation and evaluation of available information against prior knowledge. When linking sensory evidence with higher‐level expectations for action, the central nervous system (CNS) in typically developing (TD) individuals relies in part on distributed and interacting cortical regions to communicate neuronal signals flexibly across the brain. Increasing evidence suggests that the balance between levels of signal and noise during information processing may be disrupted in individuals with Autism Spectrum Disorders (ASD).

Methods

Participants with and without ASD performed a visuospatial interference task while undergoing functional Magnetic Resonance Imaging (fMRI). We empirically estimated parameters characterizing participants’ latencies and their subtle fluctuations (noise accumulation) over the 16‐min scan. We modeled hemodynamic activation and used seed‐based analyses of neural coupling to study dysfunction in interference‐specific connectivity in a subset of ASD participants who were nonparametrically matched to TD participants on age, male‐to‐female ratio, and magnitude of movement during the scan.

Results

Stochastic patterns of response fluctuations reveal significantly higher noise‐to‐signal levels and a more random and noisy structure in ASD versus TD participants, and in particular ASD adults who have the greatest clinical autistic deficits. While individuals with ASD show an overall weaker modulation of interference‐specific functional connectivity relative to TD individuals, in particular between the seeds of Anterior Cingulate Cortex (ACC) and Inferior Parietal Sulcus (IPS) and the rest of the brain, we found that in ASD, higher uncertainty during the task is linked to increased interference‐specific coupling between bilateral anterior insula and prefrontal cortex.

Conclusions

Subtle and informative differences in the structure of experiencing information exist between ASD and TD individuals. Our findings reveal in ASD an atypical capacity to apply previously perceived information in a manner optimal for adaptive functioning, plausibly revealing suboptimal message‐passing across the CNS.
Activation of the glmS Ribozyme Confers Bacterial Growth Inhibition
Authors: Schüller Anna , Matzner Daniel , Lünse Christina E. , Wittmann Valentin , Schumacher Catherine , Unsleber Sandra , Brötz‐Oesterhelt Heike , Mayer Christoph , Bierbaum Gabriele , Mayer Günter
Published: December 2016

The ever‐growing number of pathogenic bacteria resistant to treatment with antibiotics call for the development of novel compounds with as‐yet unexplored modes of action. Here, we demonstrate the in vivo antibacterial activity of carba‐α‐d‐glucosamine (CGlcN). In this mode of action study, we provide evidence that CGlcN‐mediated growth inhibition is due to glmS ribozyme activation, and we demonstrate that CGlcN hijacks an endogenous activation pathway, hence utilizing a prodrug mechanism. This is the first report describing antibacterial activity mediated by activating the self‐cleaving properties of a ribozyme. Our results open the path towards a compound class with an entirely novel and distinct molecular mechanism.
Horseradish‐Peroxidase‐Catalyzed Tyrosine Click Reaction
Authors: Sato Shinichi , Nakamura Kosuke , Nakamura Hiroyuki
Published: December 2016

The efficiency of protein chemical modification on tyrosine residues with N‐methylluminol derivatives was drastically improved by using horseradish peroxidase (HRP). In the previous method, based on the use of hemin and H2O2, oxidative side reactions such as cysteine oxidation were problematic for functionalization of proteins selectively on tyrosine residues. Oxidative activation of N‐methylluminol derivatives with a minimum amount of H2O2 prevented the occurrence of oxidative side reactions under HRP‐catalyzed conditions. As probes for HRP‐catalyzed protein modification, N‐methylluminol derivatives showed much higher efficiency than tyramide without inducing oligomerization of probe molecules. Tyrosine modification also proceeded in the presence of β‐nicotinamide adenine dinucleotide (NADH, H2O2‐free conditions).
Palladium‐Catalyzed Aerobic Synthesis of Terminal Acetals from Vinylarenes Assisted by π‐Acceptor Ligands
Authors: Matsumura Satoko , Sato Ruriko , Nakaoka Sonoe , Yokotani Wakana , Murakami Yuka , Kataoka Yasutaka , Ura Yasuyuki
Published: December 2016

Terminal acetals were synthesized from various vinylarenes and 1,2‐ or 1,3‐diols using a simple PdCl2(MeCN)2/methoxy‐p‐benzoquinone (MeOBQ)/CuCl catalyst system and 1 atm of O2 under mild reaction conditions by the anti‐Markovnikov nucleophilic attack of an oxygen nucleophile on the coordinated vinylarenes. Cyclic α,β‐unsaturated carbonyl compounds such as MeOBQ and N‐phenylmaleimide were especially effective as additives to afford higher yields of the desired terminal acetals. Kinetic experiments indicated that MeOBQ operates as a π‐acceptor ligand for Pd to accelerate the reaction and that the dissociation of a chloride ion from Pd precedes the rate‐determining step.
Deep Eutectic Solvent Compatible Metallic Catalysts: Cationic Pyridiniophosphine Ligands in Palladium Catalyzed Cross‐Coupling Reactions
Authors: Marset Xavier , Khoshnood Abbas , Sotorríos Lia , Gómez‐Bengoa Enrique , Alonso Diego A. , Ramón Diego J.
Published: December 2016

Cationic pyridiniophosphine ligands have been synthetized in an attempt to develop a deep eutectic solvents (DESs) compatible catalytic systems. These ligands, in combination with PdCl2, have been successfully applied to different palladium‐catalyzed cross coupling reactions, such as Suzuki–Miyaura, Sonogashira, or Heck couplings. While traditional palladium ligands in DES medium failed to reproduce the results obtained in VOC solvents, these cationic phosphines improved the catalytic activity of palladium as no other traditional ligand could in such a polar medium. In addition, the recyclability of these processes was studied, allowing us to reuse both, catalyst and solvent up to 5 times in Suzuki and Sonogashira reactions without a significant drop in the catalytic activity. Regarding the structure of the Pd catalysts, titration, NMR, and DFT studies have clearly demonstrated the coordination properties of the DES‐compatible cationic phosphine ligands.
Electrochemical Formation of FeV(O) and Mechanism of Its Reaction with Water During O−O Bond Formation
Authors: Pattanayak Santanu , Chowdhury Debarati Roy , Garai Bikash , Singh Kundan K. , Paul Amit , Dhar Basab B. , Gupta Sayam Sen
Published: December 2016

A detailed electrochemical investigation of a series of iron complexes (biuret‐modified tetraamido iron macrocycles FeIII‐bTAML), including the first electrochemical generation of FeV(O), and demonstration of their efficacy as homogeneous catalysts for electrochemical water oxidation (WO) in aqueous medium are reported. Spectroelectrochemical and mass spectral studies indicated FeV(O) as the active oxidant, formed due to two redox transitions, which were assigned as FeIV(O)/FeIII(OH2) and FeV(O)/FeIV(O). The spectral properties of both of these high‐valent iron oxo species perfectly match those of their chemically synthesised versions, which were thoroughly characterised by several spectroscopic techniques. The O−O bond‐formation step occurs by nucleophilic attack of H2O on FeV(O). A kinetic isotope effect of 3.2 indicates an atom–proton transfer (APT) mechanism. The reaction of chemically synthesised FeV(O) in CH3CN and water was directly probed by electrochemistry and was found to be first‐order in water. The pKa value of the buffer base plays a critical role in the rate‐determining step by increasing the reaction rate several‐fold. The electronic effect on redox potential, WO rates, and onset overpotential was studied by employing a series of iron complexes. The catalytic activity was enhanced by the presence of electron‐withdrawing groups on the bTAML framework. Changing the substituents from OMe to NO2 resulted in an eightfold increase in reaction rate, while the overpotential increased threefold.
Preparation of Tremorine and Gemini Surfactant Precursors with Cationic Ethynyl‐Bridged Digold Catalysts
Authors: Grirrane Abdessamad , Álvarez Eleuterio , García Hermenegildo , Corma Avelino
Published: December 2016

Tremorine and precursors of gemini surfactants were synthesised in a one‐pot, three‐step, double‐catalytic A3 coupling reaction and characterised by structural and spectroscopic methods. The cationic [AuI(L1)]SbF6 complex is a more active catalyst compared to neutral L2– and L3–AuI bis(trifluoromethanesulfonyl)imidate complexes (L1, L2=Buchwald‐type biaryl phosphane; L3=triphenylphosphine) in promoting the double A3 coupling of ethynyltrimethylsilane, secondary amines (cyclic, aliphatic, or aromatic) and formaldehyde. The solvent influences the catalytic performance by desilylation of silyl acetylene or deactivation of the catalyst by a halide anion. Acetylide‐bridged cationic digold(I) L1 and L2 complexes were isolated and characterised by means of single‐crystal X‐ray structure analysis and their spectroscopic properties. Iodine in the acetylene reagent deactivates the AuI catalyst by formation of the less active iodido‐bridged cationic digold(I) L1 complex, which was fully characterised by single‐crystal X‐ray crystal structure analysis and spectroscopy. The nature of the phosphine ligand of the gold complexes used as catalyst affects the stability and activity of the formed cationic ethynyl‐bridged AuI2–L intermediates, isolation of which lends support to the proposed double A3 coupling mechanism.
Phenyl Benzo[b]phenothiazine as a Visible Light Photoredox Catalyst for Metal‐Free Atom Transfer Radical Polymerization
Authors: Dadashi‐Silab Sajjad , Pan Xiangcheng , Matyjaszewski Krzysztof
Published: December 2016

This paper reports use of phenyl benzo[b]phenothiazine (Ph‐benzoPTZ) as a visible light‐induced metal‐free atom transfer radical polymerization (ATRP) photoredox catalyst. Well‐controlled polymerizations of various methacrylate monomers were conducted under a 392 nm visible light LED using Ph‐benzoPTZ to activate different alkyl halides. The use of the photocatalyst enabled temporal control over the growth of polymer chains during intermittent on/off periods. The polymerization was initiated and progressed only under stimulation by light and completely stopped in the absence of light. Block copolymers were synthesized to demonstrate high retention of chain end fidelity in the polymers and livingness of the process.
Probing the Peroxycarbenium [3+2] Cycloaddition Reactions with 1,2‐Disubstituted Ethylenes: Results and Insights
Authors: Xu Ze‐Jun , Wittlin Sergio , Wu Yikang
Published: December 2016

The causes for the title reaction to be limited to only the alkenes with an unsubstituted terminal alkenic carbon were explored. In some “failed” cases the cycloaddition products actually formed but rearranged concurrently. An oxygen atom or a N‐Boc (Boc=tert‐butyloxycarbonyl) group at the double bond was proven essential for acquisition of intact [3+2] cycloaddition products from 1,2‐disubstituted ethylenes.
Synchrotron X‐Ray Fluorescence Nanoprobe Reveals Target Sites for Organo‐Osmium Complex in Human Ovarian Cancer Cells
Authors: Sanchez‐Cano Carlos , Romero‐Canelón Isolda , Yang Yang , Hands‐Portman Ian J. , Bohic Sylvain , Cloetens Peter , Sadler Peter J.
Published: December 2016

A variety of transition metal complexes exhibit anticancer activity, but their target sites in cells need to be identified and mechanisms of action elucidated. Here, it was found that the sub‐cellular distribution of [Os(η6‐p‐cym)(Azpy‐NMe2)I]+ (p‐cym=p‐cymene, Azpy‐NMe2=2‐(p‐[dimethylamino]phenylazo)pyridine) (1), a promising drug candidate, can be mapped in human ovarian cancer cells at pharmacological concentrations using a synchrotron X‐ray fluorescence nanoprobe (SXRFN). SXRFN data for Os, Zn, Ca, and P, as well as TEM and ICP analysis of mitochondrial fractions suggest localization of Os in mitochondria and not in the nucleus, accompanied by mobilization of Ca from the endoplasmic reticulum, a signaling event for cell death. These data are consistent with the ability of 1 to induce rapid bursts of reactive oxygen species and especially superoxide formed in the first step of O2 reduction in mitochondria. Such metabolic targeting differs from the action of Pt drugs, offering promise for combatting Pt resistance, which is a current clinical problem.
Exploring the Chemical Reaction Space at the Formation of Chalcogenidometalate Superspheres in Ionic Liquids
Authors: Santner Silke , Yogendra Sivathmeehan , Weigand Jan J. , Dehnen Stefanie
Published: December 2016

The synthesis of anionic chalcogenidometalate superspheres can be achieved from [Ge4Se10]4− salts and SnCl4 in ionic liquids with 1‐alkyl‐(2,)3‐(di)methylimidazolium cations, denoted as (Cn(C1)C1Im)+ (alkyl = butyl for n=4, hexyl for n=6, octyl for n=8). Their formation is apparently independent from the lengths of the Cn chain, and the presence or absence of a second methyl group at the ionic liquid cation (that are exchanged for alkali metal cations in precursor compounds during the reactions), although this may appear counterintuitive. In contrast, and equally counterintuitive, the ionic liquid anion was found to play a crucial role for both the general observability as well as the crystal yield and quality of the products, although they are not part of the product: a minimum content of chloride is needed, while ionic liquids with [BF4]− anions alone do not support the product formation/crystallization. The observation suggests a subtle equilibrium of SnCl4 with according halidostannate anions that decreases the reactivity of the tin source. The finding is of particular interest, as chloride anions were shown to have been major impurities of former “chloride‐free” ionic liquid charges, which potentially led to irreproducible synthesis protocols in the literature.
A Very Short Be–Be Distance but No Bond: Synthesis and Bonding Analysis of Ng–Be2O2–Ng′ (Ng, Ng′=Ne, Ar, Kr, Xe)
Authors: Zhang Qingnan , Li Wan‐Lu , Zhao Lili , Chen Mohua , Zhou Mingfei , Li Jun , Frenking Gernot
Published: December 2016

Short interatomic distances below standard values for a single bond are usually identified with double or triple bonds. The synthesis and spectroscopic characterization of a molecule is reported where the distance between two beryllium atoms is shorter than a standard double bond but there is no bond. The cyclic diberyllium dioxide Be2O2molecule, which is coordinated by two noble gas atoms in Ng−Be2O2−Ng′ (Ng, Ng′=Ne, Ar, Kr, Xe) was isolated and spectroscopically identified in low‐temperature matrices. The complexes possess very short Be−Be distances, but the analysis of the electronic structure reveals that there is no chemical bond.
Enantioselective Tandem Oxidation/Michael–Aldol Approaches to Tetrasubstituted Cyclohexanes
Authors: Rana Nirmal K. , Joshi Harshit , Jha Rupesh K. , Singh Vinod K.
Published: December 2016

Enantioselective tandem Michael–aldol and oxidative Michael–aldol approaches have been achieved for the formation of diversely substituted cyclohexanes in total regio‐, diastereo‐ and enantioselective fashion. The presence of nitro, hydroxy and keto groups in the product provides a wide scope for further structural transformations. Furthermore, the utility of the catalytic process is demonstrated in the context of enantioselective formal synthesis of ABT‐341, a DPP4 inhibitor.
Stereoselective bioaccumulation, transformation, and toxicity of triadimefon in Scenedesmus obliquus
Authors: Xu Peng , Huang Ledan
Published: December 2016

In this study the stereoselective bioaccumulation and transformation of triadimefon and the toxicity of triadimefon and its metabolite triadimenol to the green algae Scenedesmus obliquus were studied. In growth inhibition experiments, triadimenol was more toxic than triadimefon, and (1S,2R)‐triadimenol, which has the largest fungicidal activity, presented the highest toxicity to the algae. In bioaccumulation experiments, triadimefon was rapidly taken up by algae cells, and the decrease in the concentration of triadimefon was accompanied by an increase in triadimenol. The transformation of S‐(+)‐ triadimefon was faster than that of the R‐(−)‐enantiomer, resulting in four triadimenol stereoisomers at different forming rates: B2 (1S, 2S) > B1 (1R, 2R) > A2 (1S, 2R) > A1 (1R, 2S). Thus, it is necessary to explore the enantioselective toxicology and ecological fate of these chiral pesticides in an environmental risk assessment. Also, their metabolites should be paid specific attention to since they may pose higher ecological risks.
Impeller diameter and submergence effects in solids drawdown with up‐pumping impellers
Authors: Myers Kevin J. , Pandit Anand K. , Janz Eric E. , Fasano Julian B.
Published: December 2016

Floating solids drawdown speeds of up‐pumping pitched‐blade and hydrofoil impellers increase with increasing impeller submergence, with the pitched‐blade speed increasing more rapidly than that of the hydrofoil. For submergences greater than 40 % of the vessel diameter, performance of the pitched‐blade impeller is adversely affected by the discharge flow impinging on the vessel wall rather than the free liquid surface. Drawdown speeds of both impeller types decrease in a similar manner with increasing impeller diameter. For both impeller types, drawdown torque continually increases with increasing impeller diameter, while drawdown power exhibits a minimum at an intermediate impeller to tank diameter ratio; however, power is not a strong function of impeller diameter to tank diameter ratio over the range of this parameter typically used industrially (D/T ranging from 0.2 to 0.5 was studied in this work). Drawdown torque and power of the hydrofoil impeller are lower than those of the pitched‐blade impeller, with the differences between the impeller types increasing rapidly with submergence.
Gas holdup, bubble behaviour, and mass transfer characteristics in a two‐stage internal loop airlift reactor with different screens
Authors: Zhang Xiaobo , Guo Kai , Qi Wenzhe , Zhang Ting , Liu Chunjiang
Published: December 2016

Screen internals were used in a two‐dimensional two‐stage internal loop airlift reactor (ILALR). The influence of screens on the hydrodynamics and mass transfer characteristics in the two‐stage ILALR, including gas holdup, mean bubble diameter, bubble rise velocity, and volumetric mass transfer coefficient (KLa), have been experimentally investigated. It is found that screens can efficiently break bubbles up. Radial bubble velocity distribution is more uniform when screens are installed. Mean bubble diameter with smaller screen pores seems smaller and slightly increases with the increasing of superficial gas velocity Ug. A larger gas holdup and KLa can be obtained when a suitable screen is mounted. The variation trend of overall gas holdup and interfacial area a with Ug is similar. A nearly constant liquid‐side mass transfer coefficient (KL) is found. The empirical correlations for the overall gas holdup and KLa have been proposed, which fit the experimental data well.
Sacrificial Templating Fabrication of Hierarchically Porous Nitrogen‐Doped Carbon Nanosheets as Superior Oxygen Reduction Electrocatalysts
Authors: Huang Tao , Yang Chongqing , Wang Xinjing , Qiu Feng , Jing Fan , Jiang Jianzhong , Liu Ruili , Han Sheng , Wu Dongqing
Published: December 2016

An unprecedented sacrificial templating strategy towards hierarchically porous N‐doped carbon nanosheets (PNC‐A) proceeds by the thermal treatment of the graphene hybrid coated with polyaniline‐encapsulated tin oxide nanoparticles, and the following etching process with acid and NH3. The resultant PNC‐A exhibits well‐defined 2D morphology, high ratio of graphitic N and pyridinic N atoms as the active sites, and hierarchically porous structures with high specific surface area. Serving as the electrocatalyst for oxygen reduction reaction (ORR) in basic media, PNC‐A exhibits excellent catalytic activity via a four‐electron pathway with half‐wave potentials of 0.76 V vs. RHE electrode in alkaline media; the diffusion‐limiting current density is 5.48 mA cm−2, which is superior to most of the reported metal‐free ORR catalysts and comparable to state‐of‐the‐art Pt/C.
Structure and Optical Properties of Carbon Nanoparticles Generated by Laser Treatment of Graphite in Liquids
Authors: Tarasenka Natalie , Stupak Aleksandr , Tarasenko Nikolai , Chakrabarti Supriya , Mariotti Davide
Published: December 2016

In this paper, we report the one‐step synthesis of luminescent carbon nanoparticles (NPs) via laser irradiation of a graphite target in a solvent [H2O, ethanol, or a 0.008 m aqueous diethylenetriaminepentaacetic acid (DTPA) solution]. This is a simple approach for the fabrication of carbon dots with tunable photoluminescence (PL) that differs from other preparation methods, as no post‐passivation step is required. The unfocused beam of the second harmonic (wavelength 532 nm) of the Nd:YAG laser was used in our experiments. The sizes of the prepared NPs were mainly distributed in the range of 1–8 nm with an average value of 3 nm. Carbon NPs of different inner structure were prepared: hexagonal diamond phase in aqueous DTPA solution, orthorhombic carbon phase in ethanol, and amorphous carbon in water. The synthesized carbon NPs have strong luminescence in the visible region, which makes them attractive for numerous biological applications. The photoluminescence of the synthesized NPs was investigated at different excitation wavelengths, from 260 to 450 nm. The highest intensities of the emission bands were detected for an excitation wavelength of 400 nm.