bluuebunny/crossref_metadata_2025 huggingface dataset:
Palbociclib induces activation of AMPK and inhibits hepatocellular carcinoma in a CDK4/6‐independent manner
Authors: Hsieh Feng‐Shu , Chen Yao‐Li , Hung Man‐Hsin , Chu Pei‐Yi , Tsai Ming‐Hsien , Chen Li‐Ju , Hsiao Yung‐Jen , Shih Chih‐Ting , Chang Mao‐Ju , Chao Tzu‐I , Shiau Chung‐Wai , Chen Kuen‐Feng
Published: April 2017

Palbociclib, a CDK4/6 inhibitor, has recently been approved for hormone receptor‐positive breast cancer patients. The effects of palbociclib as a treatment for other malignancies, including hepatocellular carcinoma (HCC), are of great clinical interest and are under active investigation. Here, we report the effects and a novel mechanism of action of palbociclib in HCC. We found that palbociclib induced both autophagy and apoptosis in HCC cells through a mechanism involving 5′ AMP‐activated protein kinase (AMPK) activation and protein phosphatase 5 (PP5) inhibition. Blockade of AMPK signals or ectopic expression of PP5 counteracted the effect of palbociclib, confirming the involvement of the PP5/AMPK axis in palbociclib‐mediated HCC cell death. However, CDK4/6 inhibition by lentivirus‐mediated shRNA expression did not reproduce the effect of palbociclib‐treated cells, suggesting that the anti‐HCC effect of palbociclib is independent of CDK4/6. Moreover, two other CDK4/6 inhibitors (ribociclib and abemaciclib) had minimal effects on HCC cell viability and the PP5/AMPK axis. Palbociclib also demonstrated significant tumor‐suppressive activity in a HCC xenograft model, which was associated with upregulation of pAMPK and PP5 inhibition. Finally, we analyzed 153 HCC clinical samples and found that PP5 expression was highly tumor specific and was associated with poor clinical features. Taken together, we conclude that palbociclib exerted antitumor activity against HCC through the PP5/AMPK axis independent of CDK4/6. Our findings provide a novel mechanistic basis for palbociclib and reveal the therapeutic potential of targeting PP5/AMPK signaling with a PP5 inhibitor for the treatment of hepatocellular carcinoma.
A study of different frequencies of major stratospheric sudden warmings in CMIP5 historical simulations
Authors: Taguchi M.
Published: April 2017

Climatological frequency of major stratospheric sudden warmings (MSSWs) during northern winter has been repeatedly investigated using model simulations, but its model‐to‐model differences are relatively unexplained. Using an archive of the Coupled Model Intercomparison Project Phase 5 (CMIP5) historical simulations with 30 models, this study investigates the MSSW frequency of the simulations by building a framework in which the frequency is decomposed into a few factors. Results first demonstrate that the multimodel differences in the MSSW frequency are closely related to the mean and variability of the zonal mean zonal wind in the extratropical stratosphere in each simulation. An important point is that for each simulation, the zonal wind variability is further represented by a combination, or product, of average strength of extreme transient planetary wave forcings from the troposphere and average deceleration response of the polar vortex to an extreme wave forcing of fixed strength. This product can be interpreted and used as a proxy of large‐scale dynamical variability of the polar vortex arising from the planetary wave‐mean flow interaction. It turns out that a large portion of the CMIP5 model simulations underestimate one or both of the factors, leading to underestimations in dynamical variability. This contributes to the general underestimation of MSSW frequency in the simulations. This study proposes that this framework can be used in general to better understand MSSW frequency in different models and climate conditions (e.g., future climate change).
The freezing level in the tropical Andes, Peru: An indicator for present and future glacier extents
Authors: Schauwecker Simone , Rohrer Mario , Huggel Christian , Endries Jason , Montoya Nilton , Neukom Raphael , Perry Baker , Salzmann Nadine , Schwarb Manfred , Suarez Wilson
Published: April 2017

Along with air temperatures, the freezing level height (FLH) has risen over the last decades. The mass balance of tropical glaciers in Peru is highly sensitive to a rise in the FLH, mainly due to a decrease in accumulation and increase of energy for ablation caused by reduced albedo. Knowledge of future changes in the FLH is thus crucial to estimating changes in glacier extents. Since in situ data are scarce at altitudes where glaciers exist (above ~4800 m above sea level (asl)), reliable FLH estimates must be derived from multiple data types. Here we assessed the FLHs and their spatiotemporal variability, as well as the related snow/rain transition in the two largest glacier‐covered regions in Peru by combining data from two climate reanalysis products, Tropical Rainfall Measuring Mission (TRMM) Precipitation Radar Bright Band data, Micro Rain Radar data, and meteorological ground station measurements. The mean annual FLH lies at 4900 and 5010 m asl, for the Cordillera Blanca and Vilcanota, respectively. During the wet season, the FLH in the Cordillera Vilcanota lies ~150 m higher compared to the Cordillera Blanca, which is in line with the higher glacier terminus elevations. Coupled Model Intercomparison Project version 5 (CMIP5) climate model projections reveal that by the end of the 21st century, the FLH will rise by 230 m (±190 m) for Representative Concentration Pathway (RCP) 2.6 and 850 m (±390 m) for RCP8.5. Even under the most optimistic scenario, glaciers may continue shrinking considerably, assuming a close relation between FLH and glacier extents. Under the most pessimistic scenario, glaciers may only remain at the highest summits above approximately 5800 m asl.
Oblique propagation of monsoon gravity waves during the northern hemisphere 2007 summer
Authors: Thurairajah Brentha , Siskind David E. , Bailey Scott M. , Carstens Justin N. , Russell James M. , Mlynczak Martin G.
Published: April 2017

We present a combination of satellite observation and high‐resolution model output to understand monsoon convection as a source of high‐latitude mesospheric gravity waves (GWs). The GWs generated over the Northern Hemisphere (NH) monsoon region during the 2007 summer and the role of the winds in focusing these GWs toward the high‐latitude middle atmosphere are analyzed using the Sounding of the Atmosphere using Broadband Emission Radiometry/Thermosphere Ionosphere Mesosphere Energetics and Dynamics (SABER/TIMED) satellite temperature data and the high‐resolution Navy Operational Global Atmospheric Prediction System‐Advanced Level Physics High Altitude (NOGAPS/ALPHA) model results. In the NH, above the stratosphere, the monsoon GW Momentum Flux (GWMF) exhibits a poleward tilt that follows the slanted structure of the easterly jet. The correlation coefficients (>0.5) between the time series of NH tropical stratospheric GWMF and the global winds also have a slanted structure that coincide with the easterly jet, confirming the modeling theory that stratospheric monsoon GWs are refracted into the summer easterly jet and can reach the high‐latitude mesosphere. Since Polar Mesospheric Clouds (PMCs) are sensitive indicators of changes in the polar summer mesosphere, we compared the time series of tropical stratospheric GWMF to the PMC occurrence frequency (OF) obtained from the Cloud Imaging and Particle Size/Aeronomy of Ice in the Mesosphere satellite data to assess the influence of this wave focusing in the mesosphere. There is a significant positive correlation between the high‐latitude PMC OF and the tropical stratospheric GWMF suggesting a definite influence of monsoon GWs on the high‐latitude mesosphere. The disagreement in correlation at the end of the PMC season is attributed to the enhancement of the quasi 5 day planetary wave dominating over the influence of monsoon GWs on PMCs.
Control of Polymorphism and Morphology in Solution Sheared Organic Field‐Effect Transistors
Authors: Galindo Sergi , Tamayo Adrián , Leonardi Francesca , Mas‐Torrent Marta
Published: April 2017

During the last decades, small molecule organic semiconductors have been successfully used as active layer in organic field‐effect transistors (OFETs). Despite the high mobility achieved so far with organic molecules, in order to progress in the field it is crucial to find techniques to process them from solution. The device reproducibility is one of the principal weak points of organic electronics for further commercialization. To achieve a high device‐to‐device reproducibility it is essential to control the morphology and polymorphism of the active layer for OFET application. In this work, the preparation of thin films is reported based on blends of the organic semiconductor dibenzo‐tetrathiafulvalene (DB‐TTF) and polystyrene by a solution shearing technique compatible with upscaling. Here, it is demonstrated that varying the deposition parameters (i.e., speed and temperature) or the solution formulation (i.e., semiconductor/binder polymer ratio) is possible to control the film morphology and semiconductor polymorphism and, hence, the different intermolecular interactions. It is demonstrated that the control of the thermodynamics and kinetics of the crystallization process is key for the device performance optimization. Further, this is the first time that DB‐TTF thin films of the α‐polymorph are reported.
ACBC to Balcite: Bioinspired Synthesis of a Highly Substituted High‐Temperature Phase from an Amorphous Precursor
Authors: Whittaker Michael L. , Joester Derk
Published: April 2017

Energy‐efficient synthesis of materials locked in compositional and structural states far from equilibrium remains a challenging goal, yet biomineralizing organisms routinely assemble such materials with sophisticated designs and advanced functional properties, often using amorphous precursors. However, incorporation of organics limits the useful temperature range of these materials. Herein, the bioinspired synthesis of a highly supersaturated calcite (Ca0.5Ba0.5CO3) called balcite is reported, at mild conditions and using an amorphous calcium–barium carbonate (ACBC) (Ca1−

x
Ba
x
CO3·1.2H2O) precursor. Balcite not only contains 50 times more barium than the solubility limit in calcite but also displays the rotational disorder on carbonate sites that is typical for high‐temperature calcite. It is significantly harder (30%) and less stiff than calcite, and retains these properties after heating to elevated temperatures. Analysis of balcite local order suggests that it may require the formation of the ACBC precursor and could therefore be an example of nonclassical nucleation. These findings demonstrate that amorphous precursor pathways are powerfully enabling and provide unprecedented access to materials far from equilibrium, including high‐temperature modifications by room‐temperature synthesis.
Highly Efficient Curtius Rearrangement Approach for the Synthesis of Unsymmetrical Sulfonimidoyl Ureas
Authors: Zhou Hao , Hong Jianquan , Huang Jiapian , Chen Zhiyuan
Published: April 2017

A highly efficient synthesis of unsymmetrical sulfoximine ureas is developed. The reaction unites simple NH‐sulfoximines and acyl azides by a formal Curtius rearrangement as the key step. This reaction could be easily scaled up to gram scale and omits the generation of hazardous byproducts, thus allowing a practical and environmentally benign path for the synthesis of medicinally important sulfonimidoyl unsymmetrical ureas.
Lead‐free Perovskite Materials (NH4)3Sb2IxBr9−x
Authors: Zuo Chuantian , Ding Liming
Published: April 2017

A family of perovskite light absorbers (NH4)3Sb2IxBr9−x (0≤x≤9) was prepared. These materials show good solubility in ethanol, a low‐cost, hypotoxic, and environmentally friendly solvent. The light absorption of (NH4)3Sb2IxBr9−x films can be tuned by adjusting I and Br content. The absorption onset for (NH4)3Sb2IxBr9−x films changes from 558 nm to 453 nm as x changes from 9 to 0. (NH4)3Sb2I9 single crystals were prepared, exhibiting a hole mobility of 4.8 cm2 V−1 s−1 and an electron mobility of 12.3 cm2 V−1 s−1. (NH4)3Sb2I9 solar cells gave an open‐circuit voltage of 1.03 V and a power conversion efficiency of 0.51 %.
Political engagement and ICTs: Internet use in marginalized communities
Authors: Nemer David , Tsikerdekis Michail
Published: April 2017

Information and communication technologies (ICTs) provide a distinctive structure of opportunities with the potential to promote political engagement. However, concerns remain over unequal technological access in our society, as political resources available on the internet empower those with the resources and motivation to take advantage of them, leaving those who are disengaged farther behind. Hence, those who face digital inequalities are not only deprived of the benefits of the so‐called Information Society, they are also deprived of exercising their civic rights. To promote political engagement among the marginalized, we analyze different sociotechnical factors that may play a role in promoting their inclusion in future political activities. We employed a survey for marginalized communities to analyze a set of research questions relating to sociotechnical factors. We show that online content creation, digital freedom, and access to the mobile Internet may positively impact political engagement. The development of these factors may not only promote the inclusion of marginalized populations in future political events, but also help to build a more equal society where everyone's voice has a chance to be heard.
Mechanistic Insights into Palladium‐Catalyzed Silylation of Aryl Iodides with Hydrosilanes through a DFT Study
Authors: Xu Zheng , Xu Jin‐Zhou , Zhang Jin , Zheng Zhan‐Jiang , Cao Jian , Cui Yu‐Ming , Xu Li‐Wen
Published: April 2017

The catalytic cycles of palladium‐catalyzed silylation of aryl iodides, which are initiated by oxidative addition of hydrosilane or aryl iodide through three different mechanisms characterized by intermediates R3Si−PdII−H (Cycle A), Ar−PdII−I (Cycle B), and PdIV (Cycle C), have been explored in detail by hybrid DFT. Calculations suggest that the chemical selectivity and reactivity of the reaction depend on the ligation state of the catalyst and specific reaction conditions, including feeding order of substrates and the presence of base. For less bulky biligated catalyst, Cycle C is energetically favored over Cycle A, through which the silylation process is slightly favored over the reduction process. Interestingly, for bulky monoligated catalyst, Cycle B is energetically more favored over generally accepted Cycle A, in which the silylation channel is slightly disfavored in comparison to that of the reduction channel. Moreover, the inclusion of base in this channel allows the silylated product become dominant. These findings offer a good explanation for the complex experimental observations. Designing a reaction process that allows the oxidative addition of palladium(0) complex to aryl iodide to occur prior to that with hydrosilane is thus suggested to improve the reactivity and chemoselectivity for the silylated product by encouraging the catalytic cycle to proceed through Cycles B (monoligated Pd0 catalyst) or C (biligated Pd0 catalyst), instead of Cycle A.
Induced‐orientation of nitrogen monoxide and azide ion vibrations in human hemoglobin in bidistilled water solution under a static magnetic field
Authors: Calabrò Emanuele , Magazù Salvatore
Published: April 2017

In this study, we report the effects of static magnetic fields (SMFs) at 200 mT on different hemoglobin aqueous solutions, in the absence and in the presence of sucrose and trehalose, studied by FTIR spectroscopic techniques. Significant decrease in intensity of Amide I and Amide II vibration bands was observed after 6 h exposure for hemoglobin in bidistilled water solution. Also, it was observed that the decrease in intensity of the Amide I band was larger than the Amide II after exposure. This result can be explained assuming that an SMF induces increase of hydrogen bonding in hemoglobin in bidistilled water solution. In particular, the use of second‐derivative analysis highlighted two absorption peaks at 1907 and 2022 cm−1 that can be attributed to nitrogen monoxide vibration and antisymmetric stretch of azide ion bound, respectively. These vibrations increased significantly after exposure to the SMF (P < 0.01). This result can be explained assuming that exposure to an SMF induces the orientation of nitrogen monoxide and azide ion ligands toward the direction of the field. Finally, it was observed that the addition of sucrose and trehalose in hemoglobin aqueous solution inhibited such alterations, suggesting that bioprotective effectiveness of these disaccharides occurs after exposure to an SMF. Bioelectromagnetics. 38:447–455, 2017. © 2017 Wiley Periodicals, Inc.
Alternative splicing switches: Important players in cell differentiation
Authors: Fiszbein Ana , Kornblihtt Alberto R.
Published: April 2017

Alternative splicing (AS) greatly expands the coding capacities of genomes by allowing the generation of multiple mature mRNAs from a limited number of genes. Although the massive switch in AS profiles that often accompanies variations in gene expression patterns occurring during cell differentiation has been characterized for a variety of models, their causes and mechanisms remain largely unknown. Here, we integrate foundational and recent studies indicating the AS switches that govern the processes of cell fate determination. We include some distinct AS events in pluripotent cells and somatic reprogramming and discuss new progresses on alternative isoform expression in adipogenesis, myogenic differentiation and stimulation of immune cells. Finally, we cover novel insights on AS mechanisms during neuronal differentiation, paying special attention to the role of chromatin structure.
President's Page
Authors: Connaway Lynn Silipigni
Published: April 2017

EDITOR'S SUMMARY

ASIS&T president Lynn Silipigni Connaway attended the ASIS&T Regional Meeting at OCLC on March 3, 2017. Special Interest Group/Information and Learning Sciences (SIG/ILS) has launched and will have a presence at the 2017 ASIS&T Annual Meeting in Washington, DC, from October 27 to November 1. In order to facilitate international attendees at the meeting, ASIS&T will be offering visa support documents by request. A conference put together by the Asia Pacific, Taiwan and Europe chapters titled “ASIS&T Presentation: Professional Organizations in Career Development” took place at the iConference in Wuhan, China, on March 24. The Board of Directors has approved a new marketing policy. The search for a new ASIS&T executive director continues. Finally, a respected pioneer in the information science field, Dr. Eugene Garfield, passed away in February. A memorial and account of his life can be found in Inside ASIS&T Reminders and on the ASIS&T website.
Consume, Reproduce, Extend and Connect: Sustaining Our Research Lifecycle
Authors: Johnson Richard P.
Published: April 2017

EDITOR'S SUMMARY

Scholarly research is at the forefront of innovation, especially with a breadth of new technologies that can enhance the research process. However, in a race for scholars to produce more and more new findings, documentation practices and reproduction of results may be neglected. Lack of validation through reproduction can lead to a general distrust of scholarly research and experiments, but a more generous approach to information sharing could be the answer to this issue. Scholars have connected socially for centuries to share their ideas, and this practice has led to some truly innovative ideas that have shaped our world today. With willing participants sharing their ideas and their research methods, new findings can be reproduced and validated, creating a stronger and more trustworthy community of scholars.
Formation Pathways toward 2‐ and 4‐Methylbenzaldehyde via Sequential Reactions from Acetaldehyde over Hydroxyapatite Catalyst
Authors: Moteki Takahiko , Rowley Andrew T. , Bregante Daniel T. , Flaherty David W.
Published: April 2017

Condensation reactions of biomass derived C2 and C4 aldehydes form both ortho‐ and para‐tolualdehydes (2‐MB and 4‐MB, respectively). The complete reaction network and the detailed mechanisms, however, have not been fully described. Here, analysis of the products formed by sequential condensation reactions of acetaldehyde and 2‐butenal suggests that 2‐ and 4‐MB products form via aromatization of 2,4,6‐octatrienal and of highly reactive acyclic intermediate(s) formed via self‐addition of 2‐butenal, respectively. The exact positions at which C−C bonds form between C4 co‐reactants to create 4‐MB products were investigated by using reactant mixtures containing combinations of 2‐butenal, 2‐butenol, and 3‐methyl‐2‐butenal as model reactants. The last two reactants can form products that may be assigned to specific reaction pathways (not distinguishable during self‐addition of 2‐butenal) and also have decreased reactivity at specific carbon atoms. The analysis of the products suggests that 4‐MB species form via 2‐butenal self‐addition by nucleophilic attack of the α‐C to the carbonyl‐C. Additionally, Diels–Alder reactions (between C6 and C2 intermediates) do not contribute in any significant manner to the formation of 4‐MB. These findings complete the description of the reaction network that forms 2‐ and 4‐MB from acetaldehyde on hydroxyapatite.
Kinetic Modeling of an Enzymatic Redox Cascade In Vivo Reveals Bottlenecks Caused by Cofactors
Authors: Milker Sofia , Fink Michael J. , Oberleitner Nikolin , Ressmann Anna K. , Bornscheuer Uwe T. , Mihovilovic Marko D. , Rudroff Florian
Published: April 2017

We describe the development of a kinetic model for the simulation and optimization of an in vivo redox cascade in E. coli in which a combination of an alcohol dehydrogenase, an enoate reductase, and a Baeyer–Villiger monooxygenase is used for the synthesis of lactones. The model was used to estimate the concentrations of active enzyme in the sequential biotransformations to identify bottlenecks together with their reasons and how to overcome them. We estimated adapted Michaelis–Menten parameters from in vitro experiments with isolated enzymes and used these values to simulate the change in the concentrations of intermediates and products during the in vivo cascade reactions. Remarkably, the model indicated that the fastest enzyme was rate‐determining because of the unexpectedly low concentration of the active form, which opens up reversible reaction channels towards byproducts. We also provide substantial experimental evidence that a low intracellular concentration of flavin and nicotinamide cofactors drastically decreased the performance of the in vivo cascade drastically.
Electrospun Nd3+‐Doped LiMn2O4 Nanofibers as High‐Performance Cathode Material for Li‐Ion Capacitors
Authors: Vijayan Shobana , Kirubasankar Balakrishnan , Pazhamalai Parthiban , Solarajan Arun Kumar , Angaiah Subramania
Published: April 2017

Electrospun high‐voltage spinel‐typeLiNd0.01Mn1.99O4 nanofibers (LNdMO NFs) were successfully prepared through the electrospinning technique. The thermal behavior of the electrospun precursor fibrous mat was assessed by thermogravimetric/differential thermal analysis. The crystallite structure and phase purity of Nd3+‐doped LiMn2O4 was confirmed by X‐ray diffraction studies. The chemical structure of the electrospun LNdMO NFs was characterized by Raman spectroscopy studies. The morphology of the nanofibers was examined by using field‐emission scanning electron microscopy. A Li‐ion capacitor (LIC) coin cell was fabricated by using high‐voltage insertion LNdMO NFs as the cathode and black pearl carbon as the anode with electrospun PVdF membrane containing 1 M LiNO3 as the separator and electrolyte. The electrochemical performance of the assembled LIC coin cell was characterized by using cyclic voltammetry, galvanostatic charge−discharge and electrochemical impedance spectroscopy. The LIC was capable of operating over wide potential window of 1.6 V with excellent capacitance retention of 86 % even after 2500 continuous galvanostatic charge−discharge cycles at a constant current density of 1 A g−1. Furthermore, LIC delivered an energy density of 17 Wh kg−1 and a power density of 397 W kg−1. Moreover, these results show that Nd3+‐doped LiMn2O4 NFs can be considered a promising electroactive cathode material for LICs.
V2O3 Polycrystalline Nanorod Cathode Materials for Li‐Ion Batteries with Long Cycle Life and High Capacity Retention
Authors: McNulty David , Buckley D. Noel , O'Dwyer Colm
Published: April 2017

We report on the electrochemical performance of V2O3 polycrystalline nanorods (poly‐NRs) as a cathode material for Li‐ion batteries. Poly‐NRs are formed through the thermal treatment of V2O5 nanotubes in a N2 atmosphere. X‐ray and electron diffraction techniques are used to confirm the thermal reduction. Through galvanostatic cycling, we demonstrate that poly‐NRs offer excellent capacity retention over 750 cycles. The capacity retention from the 50th to the 750th cycle was an impressive 94 %, retaining a capacity of approximately 120 mAh g−1 after 750 cycles. The outstanding stability of the nanocrystal‐containing V2O3 poly‐NRs over many cycles demonstrates that vanadium(III) oxide (V2O3) performs very well as a cathode material. Full Li‐ion cells with paired a V2O3 poly‐NR cathode and a pre‐charged Co3O4 inverse opal (IO) conversion mode anode demonstrated high initial capacities and retained a capacity of 153 mAh g−1 after 50 cycles. The capacities achieved with our V2O3 poly‐NRs/Co3O4 IO full cells are comparable to the capacities obtained from the most commonly used cathode materials when cycled in a half‐cell arrangement versus pure Li metal.
Highly Conductive Water‐Based Polymer/Graphene Nanocomposites for Printed Electronics
Authors: Koutsioukis Apostolos , Georgakilas Vasilios , Belessi Vassiliki , Zboril Radek
Published: April 2017

The preparation and characterization of highly conductive carbon inks is described based on nanocomposites that combine a polystyrene‐acrylic resin or water‐soluble polymers with a hydrophilic graphene/carbon nanotube hybrid. The water‐based carbon inks showed high electrical conductivity and could be effectively used in advanced technologies such as gravure printing for printed electronics. Moreover, the conductivity was shown to be increased with a power law of the nanohybrid volume fraction, with an exponent close to that predicted from the percolation theory, indicating a limited impact of the polymer tunneling barrier on the electrical conductivity of such nanocomposites.
An Aminocatalyzed Stereoselective Strategy for the Formal α‐Propargylation of Ketones
Authors: Jurberg Igor D.
Published: April 2017

A two‐step reaction sequence is described for the asymmetric formal α‐propargylation of ketones. This approach takes advantage of an aminocatalyzed conjugate addition of ketones to alkylidene isoxazol‐5‐ones, followed by a controlled nitrosative degradation event. The target compounds can be accessed in broad scope, in moderate to good yields, perfect diastereocontrol and good to excellent enantioselectivity.
DFT Studies on Isoprene/Ethylene Copolymerization Catalyzed by Cationic Scandium Complexes Bearing Different Ancillary Ligands
Authors: Hu Xiaojie , Kang Xiaohui , Zhou Guangli , Wang Xingbao , Hou Zhaomin , Luo Yi
Published: April 2017

The isoprene/ethylene copolymerization catalyzed by cationic rare earth metal complexes [(η5‐C5Me5)Sc(CH2SiMe3)]+ (A) had afforded alternating isoprene‐ethylene copolymer with rich 3,4‐polyisoprene microstructures, whereas no isoprene‐ethylene copolymer was observed by using analogous [(PNPPh)Sc(CH2SiMe3)]+ (B) under the same conditions. Theoretical calculations in this work have revealed that, in the case of A, successive 3,4‐insertion of isoprene resulted in a noncovalent interaction between the C = C double bond of penultimate unit and the metal center, suppressing the further insertion of monomers due to higher energy barrier and endergonic character. On the other hand, the ethylene pre‐inserted species with alkyl active site is more suitable for the subsequent kinetically and thermodynamically favorable isoprene insertion and copolymerization is therefore realized. In the case of B, the experimentally observed cis‐1,4‐specific homopolymerization of isoprene was the outcome of both kinetic and thermodynamic control. And, the unfavorable ethylene insertion into the isoprene pre‐inserted species with allyl active site could account for the experimental finding that no isoprene‐ethylene copolymer was obtained. These computational results are expected to provide some hints for the design of rare earth copolymerization catalysts.
Theoretical Simulation of the Vibrationally Resolved UV Absorption Spectrum of Acryloyl Fluoride
Authors: Cheng Yuanyuan , Liu Yajun
Published: April 2017

Acryloyl fluoride is an ideal molecule for investigating the phenomenon of hindered internal rotation. In concert with recently acquired high‐resolution UV absorption spectrum of acryloyl fluoride, in this study, the absorption spectra of the s‐trans and s‐cis isomers of acryloyl fluoride were theoretically simulated. The simulated spectra were convoluted by a Gaussian function with displacement, distortion, Franck‐Condon, Herzberg‐Teller, and Duschinsky effects in the framework of the time‐independent model. The statistical vibronic transition analysis reveals the unity of the spectrum transition property, the relevant normal modes, and the primary geometrical variations, enriching the understanding of the experimental observation. The discrepancy between the theoretical and experimental spectra was interpreted clearly.
Das Schülerlabor „Unser Raumschiff Erde“
Authors: van de Sand Markus , Griesbeck Axel , Henneken Heike , Ruschewitz Uwe
Published: April 2017

Das Schülerlabor „Unser Raumschiff Erde“ der Universität zu Köln wurde 2010 aus Mitteln der zdi‐Initiative des Landes NRW gegründet. Inhaltlich werden Versuche zu den Themen Sonne, Ökosphäre, Sensoren und Wasser angeboten. Schülerinnen und Schüler der Mittelstufe führen dabei im Klassenverbund zu einem der Oberthemen verschiedene stark interdisziplinär ausgerichtete Versuche in eintägigen Veranstaltungen durch, die von Studierenden des Lehramts betreut werden. Der Oberstufenbereich hingegen richtet sich an besonders interessierte Schülerinnen und Schüler, die im Rahmen von mehrtätigen Ferienkursen anspruchsvolle Versuche durchführen können, die sich an der Forschung des Departments für Chemie und der Fachgruppe Physik orientieren und bewusst über das hinausgehen, was an Schulen experimentell möglich ist. Diese Experimente werden teilweise von Lehramtsstudierenden im Rahmen von Abschlussarbeiten (Bachelor‐, Master‐ und Staatsexamensarbeiten) entwickelt und dann in Kursen mit den Schülerinnen und Schülern zusammen durchgeführt.
Impact of sleep, fatigue, and systemic inflammation on neurocognitive and behavioral outcomes in long‐term survivors of childhood acute lymphoblastic leukemia
Authors: Cheung Yin Ting , Brinkman Tara M. , Mulrooney Daniel A. , Mzayek Yasmin , Liu Wei , Banerjee Pia , Panoskaltsis‐Mortari Angela , Srivastava Deokumar , Pui Ching‐Hon , Robison Leslie L. , Hudson Melissa M. , Krull Kevin R.
Published: April 2017

BACKGROUND

Long‐term survivors of childhood acute lymphoblastic leukemia (ALL) are at risk for neurocognitive impairment, which may be associated with fatigue, sleep problems, systemic inflammation, and oxidative stress. We examined these associations among survivors of childhood ALL treated with chemotherapy only.

METHODS

Survivors of childhood ALL (male, n = 35 and female, n = 35; mean age, 14.3 years [standard deviation, 4.7 years] and mean years from diagnosis, 7.4 years [standard deviation, 1.9 years]) completed neurocognitive testing, behavioral ratings, and reported sleep quality and fatigue symptoms 5 years after diagnosis. Serum was collected concurrently and assayed for interleukin (IL)‐1β and IL‐6, tumor necrosis factor α (TNF‐α), high‐sensitivity C‐reactive protein (hsCRP), malondialdehyde, myeloperoxidase, and oxidized low‐density lipoprotein. General linear modeling was used to assess associations among biomarkers and functional outcomes, adjusting for age and stratified by sex.

RESULTS

Survivors performed worse than population norms on executive function and processing speed and reported more behavioral problems (P < .05 adjusted for multiple comparison). In female survivors, fatigue was associated with poor executive function (r = 0.41; P = .02), processing speed (r = 0.56; P < .001), and attention (r = 0.36‐0.55; P < .05). Female survivors with frequent nighttime awakening displayed more inattention (P = .01), hyperactivity (P = .03), and aggression (P = .01). Worse executive function, processing speed, and behavioral symptoms were observed in female survivors with higher levels of IL‐6, IL‐1β, and hsCRP (P < .05). Male survivors with high levels of TNF‐α demonstrated worse organization (P = .03), but no significant associations between neurocognitive outcomes and sleep/fatigue measures were observed.

CONCLUSION

Neurocognitive function in female survivors of childhood ALL appears more susceptible to the effects of sleep disturbance and fatigue. Systemic inflammation may play a role in neurocognitive impairment and behavioral symptoms. Cancer 2017;123:3410‐9. © 2017 American Cancer Society.
In Situ PDF Study of the Nucleation and Growth of Intermetallic PtPb Nanocrystals
Authors: Saha Dipankar , Bøjesen Espen D. , Mamakhel Aref Hasen , Bremholm Martin , Iversen Bo B.
Published: April 2017

The mechanism of Pt and PtPb nanocrystal formation under supercritical ethanol conditions has been investigated by means of in situ X‐ray total scattering and pair distribution function (PDF) analysis. The metal complex structures of two different platinum precursor solutions, chloroplatinic acid and Pt(acac)2 (acac=acetylacetonate) provide atomic‐scale detail about the nucleation mechanisms after initiation of the reaction with Pb(acac)2 by heating. The stronger Pt−O chemical bonding in the Pt(acac)2 precursor complex compared with the Pt−Cl bonding in the chloroplatinic acid precursor complex leads to a much slower reduction of the Pt center, and this allows more optimal co‐reduction conditions providing a pathway for formation of phase‐pure intermetallic PtPb product. The matching chemistry of the Pt(acac)2 and Pb(acac)2 precursors allow development of a facile continuous flow supercritical ethanol process for obtaining phase‐pure hexagonal PtPb nanocrystals. The study thus highlights the importance of in situ studies in revealing atomic‐scale information about nucleation mechanisms, which can be used in design of specific synthesis pathways, and the new continuous‐flow process to obtain PtPb nanocrystals holds potential for large‐scale production.
The Moral Order in Family Mediation: Negotiating Competing Values
Authors: Smithson Janet , Barlow Anne , Hunter Rosemary , Ewing Jan
Published: April 2017

We used discourse analysis to study how mediators and parties negotiate competing priorities and values during the family mediation process. We drew on understandings of practical morality, specifically the concept of a moral order, to studyUKmediation session talk. Our analysis highlighted the contradictory moral orders drawn on by parties and mediators. The saliency of moral categories and concerns in parenting is demonstrated, and we consider the problems this causes in the “no‐fault” context of mediation.
Engineering the Pores of Biomass‐Derived Carbon: Insights for Achieving Ultrahigh Stability at High Power in High‐Energy Supercapacitors
Authors: Thangavel Ranjith , Kaliyappan Karthikeyan , Ramasamy Hari Vignesh , Sun Xueliang , Lee Yun‐Sung
Published: April 2017

Electrochemical supercapacitors with high energy density are promising devices due to their simple construction and long‐term cycling performance. The development of a supercapacitor based on electrical double‐layer charge storage with high energy density that can preserve its cyclability at higher power presents an ongoing challenge. Herein, we provide insights to achieve a high energy density at high power with an ultrahigh stability in an electrical double‐layer capacitor (EDLC) system by using carbon from a biomass precursor (cinnamon sticks) in a sodium ion‐based organic electrolyte. Herein, we investigated the dependence of EDLC performance on structural, textural, and functional properties of porous carbon engineered by using various activation agents. The results demonstrate that the performance of EDLCs is not only dependent on their textural properties but also on their structural features and surface functionalities, as is evident from the electrochemical studies. The electrochemical results are highly promising and revealed that the porous carbon with poor textural properties has great potential to deliver high capacitance and outstanding stability over 300 000 cycles compared with porous carbon with good textural properties. A very low capacitance degradation of around 0.066 % per 1000 cycles, along with high energy density (≈71 Wh kg−1) and high power density, have been achieved. These results offer a new platform for the application of low‐surface‐area biomass‐derived carbons in the design of highly stable high‐energy supercapacitors.
Fluoropolymer‐Stabilized Chromophore–Catalyst Assemblies in Aqueous Buffer Solutions for Water‐Oxidation Catalysis
Authors: Eberhart Michael S. , Wee Kyung‐Ryang , Marquard Seth , Skinner Kasey , Wang Degao , Nayak Animesh , Meyer Thomas J.
Published: April 2017

Here, the application of the fluorinated polymer [Dupont AF, a copolymer of 4,5‐difluoro‐2,2‐bis(trifluoromethyl)‐1,3‐dioxole and tetrafluoroethylene] is described in stabilizing phosphonate‐derivatized molecular assemblies on oxide electrodes. In the procedure, the polymer was dip‐coated onto the surfaces of oxide electrodes with pre‐bound, phosphonate‐derivatized chromophores and assemblies, including assemblies for water oxidation. The results of the experiments showed a high degree of stabilization by the added polymer and a demonstration of its use in stabilizing surface‐bound assemblies for water‐oxidation catalysis.
The importance of topographically corrected null models for analyzing ecological point processes
Authors: McDowall Philip , Lynch Heather J.
Published: April 2017

Analyses of point process patterns and related techniques (e.g., MaxEnt) make use of the expected number of occurrences per unit area and second‐order statistics based on the distance between occurrences. Ecologists working with point process data often assume that points exist on a two‐dimensionalx–yplane or within a three‐dimensional volume, when in fact many observed point patterns are generated on a two‐dimensional surface existing within three‐dimensional space. For many surfaces, however, such as the topography of landscapes, the projection from the surface to thex–yplane preserves neither area nor distance. As such, when these point patterns are implicitly projected to and analyzed in thex–yplane, our expectations of the point pattern's statistical properties may not be met. When used in hypothesis testing, we find that the failure to account for the topography of the generating surface may bias statistical tests that incorrectly identify clustering and, furthermore, may bias coefficients in inhomogeneous point process models that incorporate slope as a covariate. We demonstrate the circumstances under which this bias is significant, and present simple methods that allow point processes to be simulated with corrections for topography. These point patterns can then be used to generate “topographically corrected” null models against which observed point processes can be compared.
Insights into Frustrated and Regular peri‐Substituted (Ace‐)Naphthylaminoboranes and (Ace‐)Naphthylphosphinoboranes
Authors: Furan Sinas , Hupf Emanuel , Lork Enno , Mebs Stefan , Beckmann Jens
Published: April 2017

Four peri‐substituted acenaphthylphosphinoboranes 5‐Ph2P‐Ace‐6‐BRR′ (R = R′ = H; R = H, R′ = C6F5; R = Cl, R′ = C6F5; R = R′ = C6F5), possessing functionality at the B atoms, were prepared and fully characterized. A quantum‐chemical analysis of these and previously known (ace‐)naphthylaminoboranes and (ace‐)naphthylphosphinoboranes revealed that these compound classes can be divided into three subclasses, namely: regular Lewis pairs (LPs) with predominately attractive peri interactions; frustrated Lewis pairs (FLPs) with predominately repulsive peri interactions; and regular Lewis pairs with predominately repulsive peri interactions. The latter subclass is a straightforward example of the enforced proximity donor concept. A detailed bond analysis showed no principal difference between attractive and enforced B–P bonds in (ace‐)naphthylphosphinoboranes.
Synthesis, Crystal Structure and Magnetic Properties of Three {CrIIIMnII} Heterodimetallic Complexes Based on Heteroleptic Cyanido‐Bearing CrIII Building Blocks
Authors: Alexandru Maria‐Gabriela , Visinescu Diana , Braun‐Cula Beatrice , Lloret Francesc , Julve Miguel
Published: April 2017

The use of the heteroleptic [CrIII(AA)(CN)4]– complexes as ligands towards the preformed [MnII(tptz)]2+ and [MnII(pyim)2]2+ species afforded the heterometallic compounds of formula [MnII(tptz)(H2O)(NO3)(µ‐NC)CrIII(ampy)(CN)3]·CH3CN (1), [MnII(tptz)(H2O)(NO3)(µ‐NC)CrIII(phen)(CN)3]·H2O (2) and {[MnII(pyim)2][(µ‐NC)Cr(phen)(CN)3]2}·3H2O (3) [AA = 2‐aminomethylpyridine (ampy) and 1,10‐phenanthroline (phen), tptz = 2,4,6‐tris(2‐pyridyl)‐1,3,5‐triazine and pyim = 2‐(1H‐imidazol‐2‐yl)pyridine]. 1 and 2 are neutral heterodinuclear complexes, where the [CrIII(AA)(CN)4]– building block acts as a monodentate ligand through one of its four cyanido groups towards a manganese(II) ion with seven coordination sites completed by a tridenate tptz molecule, a bidentate nitrate anion and a water molecule. Compound 3 is a neutral heterotrinuclear complex made up by two peripheral [CrIII(AA)(CN)4]– units acting as monodentate ligands through one of their cyanido groups towards an inner [MnII(pyim)2]2+ entity. Each manganese(II) ion in 3 is six‐coordinate with two cyanido nitrogen atoms and two bidentate pyim molecules, building a distorted octahedral surrounding. The values of the CrIII–MnII distance across the bridging cyanido ligand are 5.3766(7) (1), 5.3194(6) (2) and 5.3245(8) and 5.4538(7) Å (3). The magnetic properties of 1–3 were investigated in the temperature range 1.9–300 K. Overall antiferromagnetic behaviour is observed for all three compounds, with the antiparallel alignment of the local spins leading to either a ground‐state spin triplet (1 and 2) or a spin doublet (3). The values of the magnetic coupling between the CrIII and MnII ions across the single cyanido bridges are J = –7.40(2) (1), –6.65(2) (2) and –6.41(2) and –4.65(2) cm–1 (3), with the spin Hamiltonian being defined as H = –J(SCr1·SMn1) (1 and 2) and H = –J1(SCr1·SMn1) – J2(SCr2·SMn2) (3). These values could be correlated with the Mn–N–Ccyanido angle, and they agree with those reported for this exchange pathway in other magneto‐structural studies.
On the Distribution of Linear versus Angular Naphthalenes in Aromatic Tetradehydro‐Diels–Alder Reactions – Effect of Linker Structure and Steric Bulk
Authors: Chinta Bhavani Shankar , Baire Beeraiah
Published: April 2017

We report here a systematic study of the aromatic tetradehydro‐Diels–Alder (Ar‐TDDA) reaction to elucidate the factors that have significant effects on the distribution of linear and angular naphthalene products. Two factors were studied, that is, the nature of the linker and the steric bulk of the substituent of the enyne part. The structure of the linker has a tremendous effect on the product distribution. The effect of the steric bulk of the substituent is dependent on the linker structure, in other words, different preferences are observed for different linkers.
Experimental and Theoretical Study of Combustion under Elevated Pressure within Porous Inert Media
Authors: Bedoya Cesar , Zarzalis Nikolaos , Habisreuther Peter
Published: April 2017

Gas combustion occurring within porous inert media (PIM) results in intensified heat and mass transfer in comparison to free laminar combustion. This leads to considerably lower emissions of pollutant species, that is, NOx and CO, larger flame stability range, lower thermo‐acoustic instabilities, gradual response to operative changes, and geometric flexibility of design. In this work, experiments were carried out to describe the influence of flow rate, pressure, temperature, and air‐to‐fuel ratio on the flame stability within PIM at nearly adiabatic conditions. The macroscopic thermal flame thickness and the burning velocity were calculated from measured temperature profiles and flow rates. As the main result, it was observed that the pressure effect on the burning velocity can differ considerably from that of laminar free flames, that is, the increase of pressure can positively affect the burning velocity. The obtained results were supported by theoretical modeling. A new model to average the species production rates in a volume‐averaged numerical model was proposed. The model considered spatial deviations of temperature and mass fractions along the cross‐sectional area using presumed probability density functions. Using this new model, results of burning velocities and profiles of average temperature were satisfactorily predicted when compared to experimental results shown here. Furthermore, easy‐to‐use tools for porous burner design were formulated and validated.
A chronology of post‐glacial landslides suggests that slight increases in precipitation could trigger a disproportionate geomorphic response
Authors: Johnson Bradley G. , Smith Jacqueline A. , Diemer John A.
Published: April 2017

Large, deep‐seated landslides are common throughout the south‐eastern San Juan Mountains of Colorado and New Mexico, but their timing and initiation are not well understood. Determining when the landslides occurred would aid in clarifying the mechanisms for initiating landslides in the region and would help us to understand post‐glacial landscape evolution. We studied seven pre‐historic landslides located within the Tertiary volcanic rocks of the San Juan Volcanic Field. The landslides range in area from ~0.8 km2 to ~11.3 km2 and most are located in areas that were previously mapped as having been ice‐covered during the last glaciation. Landslide deposits were dated using a variety of methods including surface exposure dating (chlorine‐36, 36Cl), radiocarbon dating of basal bog sediments and organic material buried in soils, and relative soil development. The resulting limiting ages range from approximately 14 ka to 2 ka and show that deep‐seated landsliding has occurred throughout the post‐glacial period. This broad range in ages is inconsistent with our initial hypothesis, which proposed that landslides were likely the result of debuttressing of glacial walls during glacial retreat. Furthermore, the timing of landslides does not seem to correlate with documented post‐glacial climatic shifts. Therefore, we conclude that landsliding in the region was the result of wetter than normal periods lasting months to years acting on weak bedrock preconditioned to failure and prepared by glacial debuttressing. Our findings suggest that the study area is likely still susceptible to deep‐seated landsliding and may become even more prone to large‐scale slope failure if future climate change increases precipitation in the San Juan Mountains. Copyright © 2017 John Wiley & Sons, Ltd.
Forecasting the volatility of Nikkei 225 futures
Authors: Asai Manabu , McAleer Michael
Published: April 2017

This article proposes an indirect method for forecasting the volatility of futures returns, based on the relationship between futures and the underlying asset for the returns and time‐varying volatility. The paper considers the stochastic volatility model with asymmetry and long memory, using high frequency data of the underlying asset, for forecasting its volatility. The empirical results for Nikkei 225 futures indicate that the adjusted R2 supports the appropriateness of the indirect method, and that the new method based on stochastic volatility models with asymmetry and long memory outperforms the forecasting model based on the direct method using the pseudo long time series.