bluuebunny/crossref_metadata_2025 huggingface dataset:
Absence of a detectable lunar nanodust exosphere during a search with LRO's LAMP UV imaging spectrograph
Authors: Grava C. , Stubbs T. J. , Glenar D. A. , Retherford K. D. , Kaufmann D. E.
Published: May 2017

The Lyman‐Alpha Mapping Project (LAMP) UV spectrograph on board the Lunar Reconnaissance Orbiter (LRO) performed a campaign to observe the Moon's nanodust exosphere, evidence for which was provided by the Lunar Atmosphere and Dust Environment Explorer (LADEE) Ultraviolet and Visible Spectrometer (UVS) during the 2014 Quadrantid meteoroid stream. These LADEE/UVS observations were consistent with a nanodust exosphere modulated by meteoroid impacts. LRO performed off‐nadir maneuvers around the peak of the 2016 Quadrantids, in order to reproduce, as closely as possible, the active meteoroid environment and observing geometry of LADEE/UVS. We analyzed LAMP spectra to search for sunlight backscattering from nanodust. No brightness enhancement attributable to dust, of any size, was observed. We determine an upper limit for dust column concentration of ~105 cm−2 for grains of radius ~25 nm, and an upper limit for dust column mass of ~10−11 g cm−2, nearly independent of grain size for radii <100 nm.
Radiation belt seed population and its association with the relativistic electron dynamics: A statistical study
Authors: Tang C. L. , Wang Y. X. , Ni B. , Zhang J.‐C. , Reeves G. D. , Su Z. P. , Baker D. N. , Spence H. E. , Funsten H. O. , Blake J. B.
Published: May 2017

Using the particle data measured by Van Allen Probe A from October 2012 to March 2016, we investigate in detail the radiation belt seed population and its association with the relativistic electron dynamics during 74 geomagnetic storms. The period of the storm recovery phase was limited to 72 h. The statistical study shows that geomagnetic storms and substorms play important roles in the radiation belt seed population (336 keV electrons) dynamics. Based on the flux changes of 1 MeV electrons before and after the storm peak, these storm events are divided into two groups of “large flux enhancement” and “small flux enhancement.” For large flux enhancement storm events, the correlation coefficients between the peak flux location of the seed population and those of relativistic electrons (592 keV, 1 MeV, 1.8 MeV, and 2.1 MeV) during the storm recovery phase decrease with electron kinetic energy, being 0.92, 0.68, 0.49, and 0.39, respectively. The correlation coefficients between the peak flux of the seed population and those of relativistic electrons are 0.92, 0.81, 0.75, and 0.73. For small flux enhancement storm events, the correlation coefficients between the peak flux location of the seed population and those of relativistic electrons are relatively smaller, while the peak flux of the seed population is well correlated with those of relativistic electrons (correlation coefficients >0.84). It is suggested that during geomagnetic storms there is a good correlation between the seed population and ≤1 MeV electrons and the seed population is important to the relativistic electron dynamics.
Tropical cyclone sensitivity to ocean coupling in the ECMWF coupled model
Authors: Mogensen Kristian S. , Magnusson Linus , Bidlot Jean‐Raymond
Published: May 2017

We present an investigation of the performance of the ECMWF coupled atmosphere‐waves‐ocean model for different ocean and atmosphere resolutions on a series of tropical cyclones in the Western Pacific with the aim to better understand the coupled feedback mechanisms in these extreme conditions. For some of the test cases, we only find little impact of coupling the atmosphere to the ocean, while in others, we observe a very large impact. To further understand these differences, we have selected two tropical cyclones (TCs) as case studies: TC Haiyan (with small impact of coupling) and TC Neoguri (with large impact of coupling). The comparison between these two cases suggests that the upper ocean stratification is the key in determining the strength of the coupled feedback. A strong coupled feedback is found whenever the ocean heat content of the upper layer is low while a very weak coupled feedback is found whenever the ocean has a thick warm mixed layer. The oceanographic response to tropical cyclones for the two storms has been compared to sea surface temperature and derived surface currents from drifting buoys and to subsurface observations from Argo and ship launched XBT's. These comparisons show that we are able to realistically reproduce the atmospheric and oceanographic interaction during tropical cyclone conditions which gives us confidence that the coupled modeling system is physically sound.
Impact of typhoons on the Changjiang plume extension in the Yellow and East China Seas
Authors: Lee Joon Ho , Moon Il‐Ju , Moon Jae‐Hong , Kim Sung‐Hun , Jeong Yeong Yun , Koo Jun‐Ho
Published: May 2017

It is well known that river discharges, winds, ocean currents, and tides are major dynamical factors that determine the distribution and extension of the Changjiang plume (CP) in the Yellow and East China Seas (YECS). Using observations and numerical experiments, this study demonstrates that, in addition to these factors, typhoons in the YECS also play a crucial role in the extension of the CP during the summer season. The hydrographic data observed at the Ieodo Ocean Research Station (IORS) and by a research vessel during the period of Typhoons Ewiniar (0603) and Dianmu (1004) showed that the typhoon‐induced strong vertical mixing modified spatial distribution of the CP significantly, resulting in the delay of the CP's extension by as much as up to 20 days. A series of numerical experiments for Typhoon Dianmu also showed that the typhoon plays a blocking role for the extension of CP for up to 17 days through the vertical mixing process and the change of background winds. In particular, it is found that the delay due to Dianmu in 2010 contributed to the avoidance of potential mass mortality of marine life by preventing the low‐salinity water from spreading to the aquaculture regions near Jeju Island.
The viability of trajectory analysis for diagnosing dynamical and chemical influences on ozone concentrations in the UTLS
Authors: Bergman J. W. , Pfister L. , Kinnison D. E. , Hintsa E. J. , Thornberry T. D.
Published: May 2017

To evaluate the utility of trajectory analysis in the tropical upper troposphere/lower stratosphere, Lagrangian predictions of ozone mixing ratio are compared to observations from the Airborne Tropical TRopopause EXperiment. Model predictions are based on backward trajectories that are initiated along flight tracks. Ozone mixing ratios from analysis data interpolated onto “source locations” (at trajectory termini) provide initial conditions for chemical production models that are integrated forward in time along parcel trajectories. Model sensitivities are derived from ensembles of predictions using two sets of dynamical forcing fields, four sets of source ozone mixing ratios, three trajectory formulations (adiabatic, diabatic, and kinematic), and two chemical production models. Direct comparisons of analysis ozone mixing ratios to observations have large random errors that are reduced by averaging over 75 min (~800 km) long flight tracks. These averaged values have systematic errors that motivate a similarly systematic adjustment to source ozone mixing ratios. Sensitivity experiments reveal a prediction error minimum in parameter space and, thus, a consistent diagnostic picture: The best predictions utilize the source ozone adjustment and a chemical production model derived from Whole Atmosphere Community Climate Model (a chemistry‐climate model) chemistry. There seems to be slight advantages to using ERA‐Interim winds compared to Modern‐Era Retrospective Analysis for Research and Applications and to using kinematic trajectories compared to diabatic; however, both diabatic and kinematic formulations are clearly preferable to adiabatic trajectories. For these predictions, correlations with observations typically decrease as model error is reduced and, thus, fail as a model comparison metric.
Patient specific methods for room‐mounted x‐ray imagers for monoscopic/stereoscopic prostate motion monitoring
Authors: Stevens M. Tynan R. , Parsons Dave D. , Robar James L.
Published: May 2017

Purpose

To investigate the improvement of combined monoscopic/stereoscopic prostate motion monitoring with room‐mounted dual x‐ray systems by adopting patient specific methods.

Methods

The linac couch was used as a motion stage to simulate 40 highly dynamic real patient prostate trajectories. For each trajectory, 40 s pretreatment and 120 s treatment periods were extracted to represent a typical treatment fraction. Motion was monitored via continuous stereoscopic x‐ray imaging of a single gold fiducial and images were retrospectively divided into periods of stereoscopic and monoscopic imaging to simulate periodic blocking of the room‐mounted system by the gantry during arc‐based therapy. The accuracy of the combined motion monitoring was assessed by comparison with the linac couch log files. To estimate 3‐D marker position during monoscopic imaging, the use of population statistics was compared to both maximum likelihood estimation and stereoscopic localization based estimation of individualized prostate probability density functions (PDFs) from the pretreatment period. The inclusion of intrafraction updating was compared to pretreatment initialization alone.

Results

Combined mono/stereoscopic localization was successfully implemented. During the transitions from stereoscopic to monoscopic imaging, fiducial localization exhibits sharp discontinuities when population PDFs were employed. Patient specific PDFs successfully reduced the localization error when estimated from stereoscopic localizations, whereas maximum likelihood estimation (MLE) was too unstable in the room‐mounted geometry. Intrafraction stereoscopic updating provided further increases in accuracy. Residual error tended to decrease throughout the treatment fraction, as the patient‐specific PDFs became more refined.

Conclusions

This is the first demonstration of toggled monoscopic/stereoscopic localization using room‐mounted dual x‐ray imagers, enabling continuous intrafraction motion monitoring for these systems. We showed that both pretreatment individualization and intrafraction updating should be used to provide the most accurate motion monitoring.
MRI scanner‐independent specific absorption rate measurements using diffusion coefficients
Authors: Seo Youngseob , Wang Zhiyue J.
Published: May 2017

Objective

The purpose of this study was to measure specific absorption rate (SAR) during MRI scanning using a human torso phantom through quantification of diffusion coefficients independently of those reported by the scanner software for five 1.5 and 3 T clinical MRI systems from different vendors.

Methods

A quadrature body coil transmitted the RF power and a body array coil received the signals. With diffusion tensor imaging, SAR values for three MRI sequences were measured on the five scanners and compared to the nominal values calculated by the scanners.

Results

For the GE 1.5 T MRI system, the MRI scanner‐reported SAR value was 1.58 W kg‐1 and the measured SAR value was 1.38 W kg‐1. For the Philips 1.5 T MRI scanner, the MRI system‐reported SAR value was 1.48 W kg‐1 and the measured value was 1.39 W kg‐1. For the Siemens 3 T MRI system, the reported SAR value was 2.5 W kg‐1 and the measured SAR value was 1.96 W kg‐1. For two Philips 3 T MRI scanners, the reported SAR values were 1.5 W kg‐1 and the measured values were 1.94 and 1.96 W kg‐1. The percentage differences between the measured and reported SAR values on the GE 1.5 T, Philips 1.5 T, Siemens 3 T, and Philips 3 T were 13.5, 6.3, 24.2, 25.6, and 26.6% respectively.

Conclusion

The scanner‐independent SAR measurements using diffusion coefficients described in this study can play a significant role in estimating accurate SAR values as a standardized method.
Subjective Crepitus as a Risk Factor for Incident Symptomatic Knee Osteoarthritis: Data From the Osteoarthritis Initiative
Authors: Lo Grace H. , Strayhorn Michael T. , Driban Jeffrey B. , Price Lori Lyn , Eaton Charles B. , Mcalindon Timothy E.
Published: May 2017

Objective

Subjective crepitus is the reporting of hearing grating, cracking, or popping sounds in and/or around a joint. We aimed to evaluate whether there is an association between crepitus and incident symptomatic knee osteoarthritis (OA) in the Osteoarthritis Initiative (OAI), a multicenter longitudinal US cohort.

Methods

Knees without baseline symptomatic OA were included. Crepitus frequency was assessed using a question from the Knee Injury and Osteoarthritis Outcome Score at baseline and at 12, 24, and 36 months. Frequent knee pain and radiographs were assessed at baseline and at annual visits up to 48 months. Radiographic OA was defined as a tibiofemoral Kellgren/Lawrence grade ≥2. Symptomatic OA was defined as a knee with both frequent symptoms and radiographic OA. We performed a repeated‐measures analysis with a predictor of crepitus and outcome of incident symptomatic OA, adjusting for age, sex, and body mass index (BMI), with those never reporting crepitus as the referent group.

Results

There were a total of 3,495 participants (42.2% male), with mean ± SD age of 61.1 ± 9.2 years and a mean ± SD BMI of 28.2 ± 4.7 kg/m². The odds of incident symptomatic OA were higher with greater frequency of crepitus (never, rarely, sometimes, often, and always, with adjusted odds ratios of (referent), 1.5, 1.8, 2.2, and 3.0, respectively; P < 0.0001 for trend). The group with radiographic OA at OAI baseline but without symptoms contributed 26% of the observations but more than 75% of the incident symptomatic OA cases.

Conclusion

In those without symptomatic OA, subjective knee crepitus predicts incident symptomatic OA longitudinally, with most cases occurring in those with preexisting tibiofemoral radiographic OA but without frequent knee pain. However, an important limitation is that patellofemoral OA was not systematically evaluated within the OAI. Subjective crepitus offers utility for the identification of at‐risk individuals, predictive modeling, and future research.
A Cooperative Dimensional Strategy for Enhanced Nucleus‐Targeted Delivery of Anticancer Drugs
Authors: Wang Hebin , Li Yang , Bai Hongzhen , Shen Jie , Chen Xi , Ping Yuan , Tang Guping
Published: May 2017

Although previous efforts have focused on altering the size of drug delivery carriers with the goal of improving the efficacy of anticancer therapy, the penetration of nuclear pores still represents a formidable barrier for the existing drug delivery systems. To this end, a cooperative, dimensional strategy is employed that can considerably improve intranuclear drug delivery to augment the overall therapeutic efficacy of therapeutics requiring nuclear entry. This cooperative strategy relies on i) the pH and redox responsiveness of micelles (termed PSPD) to extend blood circulation and increase both the cellular uptake and the redox sensitivity of PSPD to reduce micelles to a size that is more capable of nuclear entry and ii) a dexamethasone‐conjugated micelle (termed Dex‐P123) to target nuclei and dilate nuclear pores to allow PSPD to freely penetrate the nuclear pores. The resulting hybrid micelles, termed PSPD/Dex‐P123, are found to deliver doxorubicin into cell nuclei more efficiently, thereby inducing more pronounced cytotoxicity against cancer cells in vitro. Importantly, a much more effective inhibition of tumor growth is observed in tumor‐bearing mice, demonstrating the feasibility of this cooperative strategy for in vivo applications. The current study defines a useful dimensional strategy to improve nuclear‐targeted and intranuclear drug delivery.
Synergistically Assembled Li2S/FWNTs@Reduced Graphene Oxide Nanobundle Forest for Free‐Standing High‐Performance Li2S Cathodes
Authors: Chen Yan , Lu Songtao , Zhou Jia , Qin Wei , Wu Xiaohong
Published: May 2017

Lithium sulfide (Li2S) has attracted increasing attention as a promising cathode because of its compatibility with more practical lithium‐free anode materials and its high specific capacity. However, it is still a challenge to develop Li2S cathodes with low electrochemical overpotential, high capacity and reversibility, and good rate performance. This work designs and fabricates a practical Li2S cathode composed of Li2S/few‐walled carbon nanotubes@reduced graphene oxide nanobundle forest (Li2S/FWNTs@rGO NBF). Hierarchical nanostructures are obtained by annealing the Li2SO4/FWNTs@GO NBF, which is prepared by a facile and scalable solution‐based self‐assembly method. Systematic characterizations reveal that in this unique NBF nanostructure, FWNTs act as axial shafts to direct the structure, Li2S serves as the internal active material, and GO sheets provide an external coating to minimize the direct contact of Li2S with the electrolyte. When used as a cathode, the Li2S/FWNTs@rGO NBF achieve a high capacity of 868 mAh g−1Li2S at 0.2C after 300 cycles and an outstanding rate performance of 433 mAh g−1Li2S even at 10C, suggesting that this Li2S cathode is a promising candidate for ultrafast charge/discharge applications. The design and synthetic strategies outlined here can be readily applied to the processing of other novel functional materials to obtain a much wider range of applications.
Bioinspired Pollen‐Like Hierarchical Surface for Efficient Recognition of Target Cancer Cells
Authors: Wang Wenshuo , Yang Gao , Cui Haijun , Meng Jingxin , Wang Shutao , Jiang Lei
Published: May 2017

The efficient recognition and isolation of rare cancer cells holds great promise for cancer diagnosis and prognosis. In nature, pollens exploit spiky structures to realize recognition and adhesion to stigma. Herein, a bioinspired pollen‐like hierarchical surface is developed by replicating the assembly of pollen grains, and efficient and specific recognition to target cancer cells is achieved. The pollen‐like surface is fabricated by combining filtering‐assisted assembly and soft lithography‐based replication of pollen grains of wild chrysanthemum. After modification with a capture agent specific to cancer cells, the pollen‐like surface enables the capture of target cancer cells with high efficiency and specificity. In addition, the pollen‐like surface not only assures high viability of captured cells but also performs well in cell mixture system and at low cell density. This study represents a good example of constructing cell recognition biointerfaces inspired by pollen–stigma adhesion.
Active Phase Transition via Loss Engineering in a Terahertz MEMS Metamaterial
Authors: Cong Longqing , Pitchappa Prakash , Lee Chengkuo , Singh Ranjan
Published: May 2017

Controlling the phase of local radiation by using exotic metasurfaces has enabled promising applications in a diversified set of electromagnetic wave manipulation such as anomalous wavefront deflection, flat lenses, and holograms. Here, we theoretically and experimentally demonstrate an active phase transition in a micro‐electromechanical system‐based metadevice where both the phase response and the dispersion of the metamaterial cavity are dynamically tailored. The phase transition is determined by the radiative and the absorptive losses in a metal–insulator–metal cavity that obeys the coupled‐mode theory. The complete understanding of the phase diagram in a reconfigurable configuration would open up avenues for designing multifunctional metadevices that can be actively switched between different phases leading to a plethora of applications in polarization control, beam deflectors, and holographic metamaterials.
A Methylidene Group in the Phosphonic Acid Analogue of Phenylalanine Reverses the Enantiopreference of Binding to Phenylalanine Ammonia‐Lyases
Authors: Bata Zsófia , Qian Renzhe , Roller Alexander , Horak Jeannie , Bencze László Csaba , Paizs Csaba , Hammerschmidt Friedrich , Vértessy Beáta G. , Poppe László
Published: May 2017

Aromatic amino acid ammonia‐lyases and aromatic amino acid 2,3‐aminomutases contain the post‐translationally formed prosthetic 3,5‐dihydro‐4‐methylidene‐5H‐imidazol‐5‐one (MIO) group. MIO enzymes catalyze the stereoselective synthesis of α‐ or β‐amino acid enantiomers, making these chemical processes environmentally friendly and affordable. Characterization of novel inhibitors enables structural understanding of enzyme mechanism and recognizes promising herbicide candidates as well. The present study found that both enantiomers of the aminophosphonic acid analogue of the natural substrate phenylalanine and a novel derivative bearing a methylidene at the β‐position inhibited phenylalanine ammonia‐lyases (PAL), representing MIO enzymes. X‐ray methods unambiguously determined the absolute configuration of all tested enantiomers during their synthesis. Enzyme kinetic measurements revealed the enantiomer of the methylidene‐substituted substrate analogue as being a mirror image relation to the natural l‐phenylalanine as the strongest inhibitor. Isothermal titration calorimetry (ITC) confirmed the binding constants and provided a detailed analysis of the thermodynamic driving forces of ligand binding. Molecular docking suggested that binding of the (R)‐ and (S)‐enantiomers is possible by a mirror image packing.

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CO2 capture in a multistage CFB: Part I: Number of stages
Authors: Boonprasop Sutthichai , Gidaspow Dimitri , Chalermsinsuwan Benjapon , Piumsomboon Pornpote
Published: May 2017

The most common technology for postcombustion of CO2 capture is the amine solvent scrubber. The energy consumption for capturing CO2 from flue gases using amine solvent technology is 15–30% of the power plant electricity production. Hence, there is a need to develop more efficient methods of removing CO2. A circulating fluidized bed using sodium or potassium carbonates is potentially such a process, as their high decomposition pressures allow regeneration at low temperatures using waste heat rather than steam from the power plant. But equilibrium data for the sorbents require the use of several cooled stages to achieve high CO2 conversions. Here, a method of computing such a number of stages for a given CO2 conversion was developed using multiphase computational fluid dynamics. It was found that it required six equilibrium stages to remove 96% of CO2 with the initial mole fraction of 0.15 in a sorption riser. © 2017 American Institute of Chemical Engineers AIChE J, 63: 5267–5279, 2017
Impact of osmotic agent on the transport of components using forward osmosis to separate ethanol from aqueous solutions
Authors: Ambrosi Alan , Lopes Corrêa Guilherme , Souza de Vargas Natiéli , Martim Gabe Lucas , Cardozo Nilo Sérgio Medeiros , Tessaro Isabel Cristina
Published: May 2017

The separation of low molecular weight organic compounds such as the ethanol from aqueous solutions represents an important area to be investigated and increment the range of applications of forward osmosis. This investigation assesses the effects of using different draw solutes for ethanol separation from dilute aqueous solutions. The influence of glucose, sucrose, sodium chloride, and magnesium chloride was evaluated in terms of total permeate, reverse solute and ethanol fluxes. Inorganic solutes promoted higher total permeate and ethanol fluxes than the organic solutes (2.5 and 1.5 times higher in average, respectively) for the same molar concentration, while presenting only 1.1 times higher reverse solute fluxes. Despite the lower ethanol flux promoted by the organic draw solutes, these osmotic agents promoted higher concentration of ethanol in the total permeate flux, suggesting that they can also be alternatives for specific processes. © 2017 American Institute of Chemical Engineers AIChE J, 63: 4499–4507, 2017
Function and effect of the inner vortex on the performance of cyclone separators
Authors: Wang Bo , Pei Binbin , Liu He , Jiang Yunchao , Xu Delong , Chen Yanxin
Published: May 2017

The inner vortex plays a key role in the performance of cyclone separators. To explore the function and effect of the inner vortex in cyclone separators, a series of metal rods and metal blades are inserted in the typical Lapple cyclone separator to reduce the intensity of the inner vortex. First, the changes in general performance of cyclones are measured by experimental methods after insertion of the metal rods and metal blades. The flow field and particle motion are then simulated, respectively, by means of a Reynolds stress model (RSM) and a Lagrangian particle tracking (LPT) model. The results show that when the length of the metal blades is less than the boundary between the inner and outer vortexes, that is, the outer vortex remains unchanged and the inner vortex is destroyed partly, the separation efficiency remains constant and the pressure drop significantly decreases. When the length of the metal blades exceeds the boundary, the inner vortex is completely destroyed, and the outer vortex is significantly damaged, which results in sharp decrease of both the separation efficiency and pressure drop. The results indicate that the inner vortex has a notable effect on the pressure drop and virtually none on the separation efficiency. © 2017 American Institute of Chemical Engineers AIChE J, 63: 4508–4518, 2017
Charting a Course for Success: The Importance of an Initial Case Plan
Authors: Hubbard Jared
Published: May 2017

When planning to set sail to a new foreign port, any seasoned sailor will carefully review the sea charts and plot out the best course to arrive quickly and safely at the destination. Indeed, only a fool would simply set sail without a plan, hoping for the best.
Having Second Thoughts? How Regret Motivates Settlement Decisions
Authors: Creo Robert A.
Published: May 2017

What is at the heart of regret?
Durch N‐heterocyclische Carbene katalysierte oxidative Dearomatisierung von Indolen zu spirocyclischen Indoleninen mit quartärem Stereozentrum
Authors: Bera Srikrishna , Daniliuc Constantin G. , Studer Armido
Published: May 2017

Eine effiziente Methode zur asymmetrischen intramolekularen Dearomatisierung von Indolen unter oxidativer Katalyse mit N‐heterocyclischen Carbenen wird vorgestellt. Nützliche, optisch aktive spirocyclische Indolenine mit quartärem Stereozentrum fallen dabei in exzellenten Ausbeuten und Stereoselektivitäten an. Die Indol‐Ausgangsverbindungen sind leicht zugänglich, und die Reaktionen verlaufen über eine intramolekulare Indolacylierung der 3‐Position mit einem in situ erzeugten Acylazolium‐Intermediat unter Bildung einer spirocyclischen Ketoneinheit.
Unterschiedliche Reaktivität von As4gegenüber Disilenen und Silylenen
Authors: Seitz Andreas E. , Eckhardt Maria , Sen Sakya S. , Erlebach Andreas , Peresypkina Eugenia V. , Roesky Herbert W. , Sierka Marek , Scheer Manfred
Published: May 2017

Über die Aktivierung von gelbem Arsen mit dem Silylen [PhC(NtBu)2SiN(SiMe3)2] (1) und dem Disilen [(Me3Si)2N(η1‐Me5C5)Si=Si(η1‐Me5C5)N(SiMe3)2] (3) wird berichtet. Die Reaktion von As4mit1führt zur präzedenzlosen As10‐Käfigverbindung [(LSiN(SiMe3)2)3As10] (2) (L=PhC(NtBu)2) mit einem As7‐Nortricyclan‐Gerüst, das von Silicium(II)‐bis(trimethylsilyl)amid‐Substituenten enthaltenden Arsasilenresten stabilisiert wird. Dagegen wird die Verbindung [Cp*{(SiMe3)2N}SiAs]2(4), die eine “Butterfly”‐ähnliche Diarsadisilabicyclo[1.1.0]butan‐Einheit enthält, durch die Reaktion von As4mit dem Disilen3gebildet. Beide Verbindungen wurden durch Einkristall‐Röntgenstrukturanalyse, NMR‐Spektroskopie und Massenspektrometrie charakterisiert. Die Ergebnisse zeigen das unterschiedliche Reaktionsverhalten von gelbem Arsen (As4) im Vergleich zum weißen Phosphor (P4) in den Reaktionen mit den entsprechenden Silylenen und Disilenen.
A Short Synthesis of (±)‐3‐Demethoxyerythratidinone by Ligand‐Controlled Selective Heck Cyclization of Equilibrating Enamines
Authors: Blackham Emma E. , Booker‐Milburn Kevin I.
Published: May 2017

A short, 5‐step total synthesis of (±)‐3‐demethoxyerythratidinone from a simple pyrrole derivative is described. Features include the formation of gram quantities of a key tricylic aziridine from a challenging photochemical cascade reaction through the use of flow photochemistry. The final step involved a highly unusual Heck cyclization whereby ligand control enabled efficient formation of the natural product in 69 % yield from the minor isomer present in an equilibrating mixture of labile enamines.
Total Syntheses of Aurachins A and B
Authors: Hattori Haruhiko , Yokoshima Satoshi , Fukuyama Tohru
Published: May 2017

Aurachins A and B are alkaloids having 3‐hydroxyquinoline N‐oxide cores. An efficient method for the synthesis of 3‐hydroxyquinoline N‐oxides was established and is amenable to the total syntheses of aurachins A and B. Alkylation of 1‐(2‐nitrophenyl)butan‐2‐one with farnesyl bromide took place selectively at the benzylic position, and subsequent treatment of the alkylated product with sodium tert‐butoxide in dimethyl sulfoxide gave aurachin B. Alkylation of 1‐(2‐nitrophenyl)butan‐2‐one with an epoxy iodide derived from farnesol was used to access aurachin A.
Confining Excitation Energy in Er3+‐Sensitized Upconversion Nanocrystals through Tm3+‐Mediated Transient Energy Trapping
Authors: Chen Qiushui , Xie Xiaoji , Huang Bolong , Liang Liangliang , Han Sanyang , Yi Zhigao , Wang Yu , Li Ying , Fan Dianyuan , Huang Ling , Liu Xiaogang
Published: May 2017

A new class of lanthanide‐doped upconversion nanoparticles are presented that are without Yb3+ or Nd3+ sensitizers in the host lattice. In erbium‐enriched core–shell NaErF4:Tm (0.5 mol %)@NaYF4 nanoparticles, a high degree of energy migration between Er3+ ions occurs to suppress the effect of concentration quenching upon surface coating. Unlike the conventional Yb3+‐Er3+ system, the Er3+ ion can serve as both the sensitizer and activator to enable an effective upconversion process. Importantly, an appropriate doping of Tm3+ has been demonstrated to further enhance upconversion luminescence through energy trapping. This endows the resultant nanoparticles with bright red (about 700‐fold enhancement) and near‐infrared luminescence that is achievable under multiple excitation wavelengths. This is a fundamental new pathway to mitigate the concentration quenching effect, thus offering a convenient method for red‐emitting upconversion nanoprobes for biological applications.
Discovery of Hexagonal Structured Pd–B Nanocrystals
Authors: Kobayashi Keigo , Kobayashi Hirokazu , Maesato Mitsuhiko , Hayashi Mikihiro , Yamamoto Tomokazu , Yoshioka Satoru , Matsumura Syo , Sugiyama Takeharu , Kawaguchi Shogo , Kubota Yoshiki , Nakanishi Hiroshi , Kitagawa Hiroshi
Published: May 2017

We report on hexagonal close‐packed (hcp) palladium (Pd)–boron (B) nanocrystals (NCs) by heavy B doping into face‐centered cubic (fcc) Pd NCs. Scanning transmission electron microscopy–electron energy loss spectroscopy and synchrotron powder X‐ray diffraction measurements demonstrated that the B atoms are homogeneously distributed inside the hcp Pd lattice. The large paramagnetic susceptibility of Pd is significantly suppressed in Pd–B NCs in good agreement with the reduction of density of states at Fermi energy suggested by X‐ray absorption near‐edge structure and theoretical calculations.
Oligonucleotide‐Addressed Covalent 3′‐Terminal Derivatization of Small RNA Strands for Enrichment and Visualization
Authors: Osipenko Aleksandr , Plotnikova Alexandra , Nainytė Milda , Masevičius Viktoras , Klimašauskas Saulius , Vilkaitis Giedrius
Published: May 2017

The HEN1 RNA 2′‐O‐methyltransferase plays important roles in the biogenesis of small non‐coding RNAs in plants and proved a valuable tool for selective transfer of functional groups from cofactor analogues onto miRNA and siRNA duplexes in vitro. Herein, we demonstrate the versatile HEN1‐mediated methylation and alkylation of small RNA strands in heteroduplexes with a range of complementary synthetic DNA oligonucleotides carrying user‐defined moieties such as internal or 3′‐terminal extensions or chemical reporter groups. The observed DNA‐guided covalent functionalization of RNA broadens our understanding of the substrate specificity of HEN1 and paves the way for the development of novel chemo‐enzymatic tools with potential applications in miRNomics, synthetic biology, and nanomedicine.
Oxidative N‐Heterocyclic Carbene Catalyzed Dearomatization of Indoles to Spirocyclic Indolenines with a Quaternary Carbon Stereocenter
Authors: Bera Srikrishna , Daniliuc Constantin G. , Studer Armido
Published: May 2017

An efficient method for the asymmetric intramolecular dearomatization of indoles by using oxidative N‐heterocyclic carbene catalysis is demonstrated. Valuable optically active spirocyclic indolenines bearing an all‐carbon quaternary stereocenter are obtained in excellent yields and with excellent enantioselectivity. The starting indoles are readily prepared and the reactions proceed through an intramolecular indole 3‐acylation with an in situ generated acyl azolium intermediate to form a spirocyclic ketone moiety.
Crystallinity‐Modulated Electrocatalytic Activity of a Nickel(II) Borate Thin Layer on Ni3B for Efficient Water Oxidation
Authors: Jiang Wen‐Jie , Niu Shuai , Tang Tang , Zhang Qing‐Hua , Liu Xiao‐Zhi , Zhang Yun , Chen Yu‐Yun , Li Ji‐Hui , Gu Lin , Wan Li‐Jun , Hu Jin‐Song
Published: May 2017

The exploration of new efficient OER electrocatalysts based on nonprecious metals and the understanding of the relationship between activity and structure of electrocatalysts are important to advance electrochemical water oxidation. Herein, we developed an efficient OER electrocatalyst with nickel boride (Ni3B) nanoparticles as cores and nickel(II) borate (Ni‐Bi) as shells (Ni‐Bi@NB) via a very simple and facile aqueous reaction. This electrocatalyst exhibited a small overpotential of 302 mV at 10 mA cm−2 and Tafel slope of 52 mV dec−1. More interestingly, it was found that the OER activity of Ni‐Bi@NB was closely dependent on the crystallinity of the Ni‐Bi shells. The partially crystalline Ni‐Bi catalyst exhibited much higher activity than the amorphous or crystalline analogues; this higher activity originated from the enhanced intrinsic activity of the catalytic sites. These findings open up opportunities to explore nickel(II) borates as a new class of efficient nonprecious metal OER electrocatalysts, and to improve the electrocatalyst performance by modulating their crystallinity.
Directing Reaction Pathways through Controlled Reactant Binding at Pd–TiO2 Interfaces
Authors: Zhang Jing , Wang Bingwen , Nikolla Eranda , Medlin J. Will
Published: May 2017

Recent efforts to design selective catalysts for multi‐step reactions, such as hydrodeoxygenation (HDO), have emphasized the preparation of active sites at the interface between two materials having different properties. However, achieving precise control over interfacial properties, and thus reaction selectivity, has remained a challenge. Here, we encapsulated Pd nanoparticles (NPs) with TiO2 films of regulated porosity to gain a new level of control over catalyst performance, resulting in essentially 100 % HDO selectivity for two biomass‐derived alcohols. This catalyst also showed exceptional reaction specificity in HDO of furfural and m‐cresol. In addition to improving HDO activity by maximizing the interfacial contact between the metal and metal oxide sites, encapsulation by the nanoporous oxide film provided a significant selectivity boost by restricting the accessible conformations of aromatics on the surface.
Polyethylene/sepiolite clay nanocomposites: Effect of clay content, compatibilizer polarity, and molar mass on viscoelastic and dynamic mechanical properties
Authors: Singh Vishwa Pratap , K.K. Vimal , Sharma Shashikant , Kapur Gurpreet Singh , Choudhary Veena
Published: May 2017

In this work, high‐density polyethylene (HDPE)‐based nanocomposites having different concentrations of Sepiolite (1–10 wt %) and compatibilizer, that is, PE‐graft‐maleic anhydride (PE‐g‐MA) of varying molecular weight and maleic anhydride content were prepared by melt compounding. The influence of Sepiolite amount and compatibilizer polarity and molar mass on the crystallization behavior [differential scanning calorimeter (DSC) and X‐ray diffraction (XRD)], rheological properties (oscillatory rheometer) and dimensional stability [dynamic mechanical analyzer (DMA) and heat deflection temperature (HDT)] of the nanocomposites was investigated. It was found that Sepiolite did not affect the crystallization behavior of HDPE. The rheological results show that the incorporation of Sepiolite into HDPE matrix up to 10 wt % increases the complex viscosity of polymer. Storage modulus and loss modulus both in oscillatory rheometry and in DMA were highest for nanocomposite prepared using 10 wt % Sepiolite owing to the improved mechanical restrain by the dispersed phase. In the presence of compatibilizer, the values of storage modulus and loss modulus were lower as compared to uncompatibilized nanocomposites at same loading of Sepiolite. The reduction in modulus is more pronounced in composites prepared using compatibilizer of lower molar mass as compared to those prepared using higher molar mass compatibilizer. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45197.
Fabrication of a novel polyhedral oligomeric silsesquioxanes/polyether‐block‐amide nano‐hybrid membrane for pervaporative separation of model fuel butanol
Authors: Nigiz Filiz Ugur , Hilmioglu Nilufer Durmaz
Published: May 2017

The present study reports the pervaporative separation capability of the pristine and polyhedral oligomeric silsesquioxanes (POSS) loaded hybrid polyether‐block‐amide (PEBA) membranes for n‐butanol recovery from the dilute n‐butanol–water mixtures. It is the first study to produce POSS‐loaded PEBA membranes for n‐butanol recovery. The morphology and crosslinking structure of the pristine and hybrid membrane were characterized by scanning electron microscopy and Fourier transform infrared spectroscopy. The thermal stability and crystallization behaviors of the pristine and hybrid membranes were investigated using thermogravimetric analysis and differential scanning calorimetry methods. Swelling experiments were also done to determine the affinity of the membranes to the n‐butanol–water mixture. The effect of increasing amount of POSS on pervaporation performance was investigated in terms of flux and the n‐butanol separation factor at 40 °C and a given n‐butanol. All the hybrid membranes exhibited high flux and n‐butanol separation factor than that of the pristine PEBA membrane. The best n‐butanol separation factor of 27.2 was obtained accompanied with 1.33 Kg m−2 h−1 of flux, when the POSS amount was 4 wt %. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45211.
Enhancement of discharged energy density of poly(ethylene oxide) by soy protein isolate
Authors: Rashidi Soheil , Zheng Zhuoyuan , Li Bin
Published: May 2017

Soy protein isolate (SPI) is used to modify energy storage performances of poly(ethylene oxide) (PEO). The pure PEO membranes are highly polar, but the extremely high energy loss led to very low discharged energy density for use. The addition of SPI in both high molecular weight PEO and low molecular weight PEO lead to greatly reduced polarization and stored energy density. However, it also largely reduces the current leakage and energy loss of the resulting membranes, leading to significantly enhanced discharged energy density. It is believed that the strong interactions between PEO and SPI are responsible for the energy storage properties aforementioned. Meanwhile, such interactions also result in a more brittle fracture behavior and reduced crystallinity of the PEO/SPI membranes. The enhanced discharged energy density and low energy loss suggest PEO/SPI membranes are promising dielectric materials for high efficiency energy storage applications where soluble and transient materials are desired. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45214.
Multifunctional epoxy resin/polyacrylonitrile‐lithium trifluoromethanesulfonate composites films with very high transparency, high dielectric permittivity, breakdown strength and mechanical properties
Authors: Sun Sheng , Zheng Longhui , Yuan Li , Guan Qingbao , Liang Guozheng , Gu Aijuan
Published: May 2017

Multifunctional transparent composite films with high dielectric permittivity (high‐k), breakdown strength, and mechanical properties are urgently required by cutting‐edge fields. Herein, novel multifunctional films were facilely prepared through building unique cross‐linked structure based on epoxy resin (EP) and polyacrylonitrile (PAN)‐lithium trifluoromethane sulfonate (LiTf) complex. Compared with high‐k materials reported previously, EP/(PAN‐LiTf) films simultaneously show very high transparency, good flexibility, high tensile, and breakdown strengths. For 0.22EP/(PAN‐LiTf) film with 22 wt % EP, its average transmittance and elongation at break are as high as 91% (600–800 nm) and 12.7%, respectively; moreover, its dielectric permittivity, AC breakdown strength and the maximum energy density are severally about 4.9, 1.8, and 15.2 times of those of EP resin, completely overcoming the sticky problems in conductor/polymer composites. The origin behind these attractive properties is intensively discussed, and believed to be attributed to the unique structure of EP/(PAN‐LiTf) films. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45218.
An exploration of anatomists’ views toward the use of body painting in anatomical and medical education: An international study
Authors: Cookson Natalie E. , Aka Justine J. , Finn Gabrielle M.
Published: May 2017

Previous research has explored the experiences of medical students using body painting as a learning tool. However, to date, faculty experiences and views have not been explored. This international qualitative study utilized a grounded theory approach with data collection through interviews with academics and clinicians who utilized body painting as part of their anatomical teaching. Twenty‐six anatomists participated in the study from 14 centers worldwide. Three themes emerged from the data: (1) the efficacy of body painting, (2) the promotion of knowledge retention and recall, (3) considerations and practicalities regarding the use of body painting as a teaching tool. Subthemes show that body painting is used as an adjunct to the curriculum for teaching surface anatomy and peer examination. Benefits included diffusing the formal curricula, high student engagement and learning for future clinical practice. Body painting was advocated for promoting knowledge retention and recall, particularly learning through the process of cognitive load due to combining the use of color and kinesthetic learning with anatomical theory. Critical discussions surfaced on the topic of undressing in the classroom due to cultural and personal considerations possibly leading to unequal involvement and different learning experiences. Overall results support previous research showing that anatomists appreciate body painting as an effective, enjoyable, engaging and cost efficient adjunct to the multimodal anatomy curriculum. The role of cognitive load theory in learning anatomy through body painting emerged from the data as a possible theoretical framework supporting learning benefits from body painting and is suggested for further investigation. Anat Sci Educ 11: 146–154. © 2017 American Association of Anatomists.
Entwicklung eines temperaturregulierenden Fotovoltaik‐Fassadenpaneels mit PCM
Authors: Seeger Julia , Horn Sebastian , Weller Bernhard
Published: May 2017

Opake Fassadenbereiche besitzen ein großes Potenzial zur Energieerzeugung durch den Einsatz von Fotovoltaik (PV). Die Leistung der Module sinkt mit zunehmender Temperatur der PV‐Zellen, wodurch sich die Verwendung im Fassadenbereich bisher hauptsächlich auf Kaltfassaden beschränkt hat, da hier die Hinterlüftung zur Kühlung der PV‐Module beiträgt. Im Unterschied zu Kaltfassaden erfolgt bei standardmäßigen Pfosten‐Riegel‐Fassaden (Warmfassaden) keine Hinterlüftung. Um auch hier den Einsatz von PV‐Modulen zu realisieren und gleichzeitig den temperaturbedingten Leistungsabfall zu minimieren, sollen die PV‐Module mit rückseitig angebrachten Latentwärmespeichern (PCM) kombiniert werden. Erreicht die Temperatur in der Fassade den festgelegten Schmelzpunkt des gewählten PCM, erfolgt ein Phasenübergang von fest zu flüssig. Dabei absorbiert das Material thermische Energie und entzieht sie auf diese Weise dem PV‐Modul, sodass ein Temperaturanstieg abgepuffert wird. Nachts wird die im PCM latent gespeicherte Wärmeenergie wieder an die Umgebung abgegeben.
The early academic progress of children with special educational needs
Authors: Parsons Samantha , Platt Lucinda
Published: May 2017

Children with special educational needs (SEN) are known to experience lower average educational attainment than other children during their school years. But we have less insight into how far their poorer educational outcomes stem from their original starting points or from failure to progress during school. The extent to which early identification with SEN delivers support that enables children who are struggling academically to make appropriate progress is subject to debate. This is complicated by the fact that children with SEN are more likely to be growing up in disadvantaged families and face greater levels of behavioural and peer problems, factors which themselves impact attainment and progress through school. In this paper, we evaluate the academic progress of children with SEN in England, drawing on a large‐scale nationally representative longitudinal UK study, the Millennium Cohort Study, linked to administrative records of pupil attainment. Controlling for key child, family and environmental factors, and using the SEN categories employed at the time of data collection, we first establish that children identified with SEN in 2008, when they were age 7, had been assessed with lower academic competence when they started school. We evaluate their progress between ages 5–7 and 7–11. We found that children identified with SEN at age 7 tended to be those who had made less progress between ages 5 and 7 than their comparable peers. However, children with SEN continued to make less progress than their similarly able peers between ages 7 and 11. Implications are discussed.
Individual, co‐operative and collaborative data use: A conceptual and empirical exploration
Authors: Van Gasse Roos , Vanlommel Kristin , Vanhoof Jan , Van Petegem Peter
Published: May 2017

In recent decades, the belief has originated that data use contributes to more thought‐out decisions in schools. The literature has suggested that fruitful data use is often the result of interactions among team members. However, up until now, most of the available research on data use has used ‘collaboration’ as an umbrella concept to describe very different types of interaction, without specifying the nature of collaboration or the degree of interdependency that takes place in interactions. Therefore, the current study investigates and describes Flemish teachers’ individual, co‐operative and collaborative data use. In doing so, the level of interdependency of teachers’ interactive activities (storytelling, helping, sharing, joint work) is taken into account. The results of a qualitative study with semi‐structured interviews show that teachers’ data use is predominantly of an individual nature and that felt interdependencies among teachers are few. The study enhances knowledge and opens the conceptual debate about teachers’ interactions in the context of data use.