bluuebunny/crossref_metadata_2025 huggingface dataset:
Substitutional defects enhancing thermoelectric CuGaTe2
Authors: Shen Jiawen , Zhang Xinyue , Chen Zhiwei , Lin Siqi , Li Juan , Li Wen , Li Shasha , Chen Yue , Pei Yanzhong
Published: February 2017

Ag-substitution enables a 75% reduction in lattice thermal conductivity and therefore a 75% enhancement in the thermoelectric figure of merit.
Enhanced perovskite electronic properties via a modified lead(ii) chloride Lewis acid–base adduct and their effect in high-efficiency perovskite solar cells
Authors: Pham Ngoc Duy , Tiong Vincent Tiing , Chen Peng , Wang Lianzhou , Wilson Gregory J. , Bell John , Wang Hongxia
Published: February 2017

19% perovskite solar cells with enhanced electronic properties of MAPbI3film through employing 2.5% PbCl2additive in the precursor.
Preparation of hypocrellin B nanocages in self-assembled apoferritin for enhanced intracellular uptake and photodynamic activity
Authors: Jiang Yue , Pang Xin , Wang Xinna , Leung Albert Wingnang , Luan Yuxia , Zhao Guanghua , Wang Pan , Xu Chuanshan
Published: February 2017

Novel hypocrellin B loaded apoferritin nanoparticles were successfully developed to increase the photosensitizer's solubility, intracellular uptake and photodynamic activity.
One-pot synthesis of redox-triggered biodegradable hybrid nanocapsules with a disulfide-bridged silsesquioxane framework for promising drug delivery
Authors: Zhou Mengyun , Du Xin , Li Weike , Li Xiaoyu , Huang Hongwei , Liao Qingliang , Shi Bingyang , Zhang Xueji , Zhang Meiqin
Published: February 2017

Redox-triggered biodegradable hybrid nanocapsules with the disulfide-bridged silsesquioxane framework were developed for promising drug delivery.
Ultralow bandgap molecular semiconductors for ambient-stable and solution-processable ambipolar organic field-effect transistors and inverters
Authors: Ozdemir Resul , Choi Donghee , Ozdemir Mehmet , Kwon Guhyun , Kim Hyekyoung , Sen Unal , Kim Choongik , Usta Hakan
Published: February 2017

New ultralow bandgap semiconductor small molecules were designed and synthesized for ambient-stable and solution-processable ambipolar organic field-effect transistors and high-gain inverters.
Borenium ionic liquids as catalysts for Diels–Alder reaction: tuneable Lewis superacids for catalytic applications
Authors: Matuszek K. , Coffie S. , Chrobok A. , Swadźba-Kwaśny M.
Published: February 2017

Ionic liquids with Lewis superacidic borenium cations were used as catalysts in solvent-less Diels–Alder cycloaddition. The extremely high catalytic activity correlated with the Lewis acidity, expressed as the Gutmann acceptor number.
Self-assembly of metal-ion-responsive supramolecular coordination complexes and their photophysical properties
Authors: He Zuoli , Li Meng , Que Wenxiu , Stang Peter J.
Published: February 2017

Herein, we describe the synthesis and characterization of two newly self-assembled supramolecular coordination complexes (SCCs) by using the cis-{Pt(PEt3)2}2+ center and two different kinds of pyridyl-derivatized ligands.
Anisotropic sliding on dual-rail hydrophilic tracks
Authors: Yang Xiaolong , Song Jinlong , Zheng Huanxi , Deng Xu , Liu Xin , Lu Xiaohong , Sun Jing , Zhao Danyang
Published: February 2017

Potential intelligent lab-on-a-chip applications were explored based on the discussion of multidimensional anisotropic sliding on milled dual-rail hydrophilic micro-tracks.
Model studies of the sequential and simultaneous statistical modification of dendritic functional groups and their implications within complex polymer architecture synthesis
Authors: Hern Faye Y. , Auty Sam E. R. , Andrén Oliver C. J. , Malkoch Michael , Rannard Steve P.
Published: February 2017

Accurate analysis of model systems by MALDI-TOF has established the diversity of structures formed during post-synthesis functionalisation of complex polymer architectures. NMR studies alone are shown to be highly misleading.
Enhancing thermoelectric performance of n-type PbSe via additional meso-scale phonon scattering
Authors: Qian Xin , Zheng Lei , Xiao Yu , Chang Cheng , Zhao Li-Dong
Published: February 2017

By introducing mesostructures, the lattice thermal conductivity at 300 K can be reduced from ∼1.3 W m−1 K−1 to ∼1.2 W m−1 K−1, and ∼0.9 W m−1 K−1 to ∼0.6 W m−1 K−1 at 923 K in an n-type PbSe–PbS system.
Recent development and understanding of polymer–nanocrystal hybrid solar cells
Authors: Chen Zhaolai , Du Xiaohang , Zeng Qingsen , Yang Bai
Published: February 2017

This review presents a general overview of polymer–nanocrystal hybrid solar cells (HSCs). The device structure and operation mechanism of bulk heterojunction HSCs are introduced, and recent works that have been done to improve the device performance or clarify the operation mechanism are summarized and discussed in detail. Also, the challenges and perspectives of HSCs are presented.
Asymmetric geometry composites arranged between parallel aligned and interconnected graphene structures for highly efficient thermal rectification
Authors: Gu Xiaomin , Zhang Shudong , Shang Mengya , Zhao Tingting , Li Nian , Li Haifeng , Wang Zhenyang
Published: February 2017

A graphene, thermal rectification device, originating in thermal conductivity saltation, can control the direction of flow and velocity of heat.
Matrix-assisted diffusion-ordered NMR spectroscopy with an invisible, tuneable matrix
Authors: Hernandez-Cid A. , Piekarska M. , Adams R. W. , Nilsson M. , Evans R. , Morris G. A.
Published: February 2017

Perfluorooctanoate is a useful “invisible matrix” for mixture analysis by diffusion-ordered NMR (DOSY) with pH-controlled diffusion resolution.
Honeycomb-like carbon nanoflakes as a host for SnO2 nanoparticles allowing enhanced lithium storage performance
Authors: Wang Hongkang , Wang Jinkai , Cao Daxian , Gu Hangyu , Li Beibei , Lu Xuan , Han Xiaogang , Rogach Andrey L. , Niu Chunming
Published: February 2017

Confining smaller and fewer SnO2 nanoparticles within honeycomb-like carbon nanoflakes demonstrated superior cycle stability and rate capability for lithium storage.
The excited-state intramolecular proton transfer properties of three imine-linked two-dimensional porous organic polymers
Authors: Jagadesan Pradeepkumar , Eder Grace , McGrier Psaras L.
Published: February 2017

The excited-state intramolecular proton transfer (ESIPT) properties of three tris(N-salicylideneaniline)-based (TSA) imine-linked porous organic polymers (POPs) were investigated.
Approximate Gibbs algorithm for blind data detection in two‐way relay networks
Authors: Jiang Zhe , Shen Xiaohong , Ge Yao , Wang Haiyan
Published: February 2017

This study investigates the blind data detection in two‐way relay networks (TWRN) that employ amplify‐and‐forward (AF) relay strategy. To blindly detect the data in TWRN in the presence of uncertain time‐frequency offsets and phase noise, the authors develop a new Bayesian‐based approximate Gibbs algorithm based on truncated Taylor series expansion approximation. In addition, the authors exploit available constraint information on parameters of interest. The authors present three receivers based on three different parameter estimation approaches. The authors further discuss the implementation issue and present diagnostic convergence analysis. The authors’ numerical results demonstrate the performance and efficacy of their proposed algorithm.
Benefits of data aggregation on energy consumption in wireless sensor networks
Authors: Lu Yao , Kuonen Pierre , Hirsbrunner Beat , Lin Mingwei
Published: February 2017

Wireless sensor networks consist of a large number of distributed sensor devices, which are connected and coordinated through multi‐hop routing. Due to the existence of correlated information and redundancy in measuring data, data messages can be combined and merged by performing data aggregation function in the routing process. To reduce energy consumption is a major optimisation objective of data aggregation approaches, which can be achieved by decreasing the compulsory communication load of routing. From the theoretical level, an energy model is proposed to validate the benefits of data aggregation on energy consumption. The key parameters which may impact the aggregation performance are further discussed. Finally, the corresponding simulations are implemented in order to verify the analysis conclusions from the theoretical model, and the comparison results can effectively reflect the advantages of data aggregation in different scenarios.
Characterization of star-forming dwarf galaxies at 0.1 ≲z ≲ 0.9 in VUDS: probing the low-mass end of the mass-metallicity relation
Authors: Calabrò A. , Amorín R. , Fontana A. , Pérez-Montero E. , Lemaux B. C. , Ribeiro B. , Bardelli S. , Castellano M. , Contini T. , De Barros S. , Garilli B. , Grazian A. , Guaita L. , Hathi N. P. , Koekemoer A. M. , Le Fèvre O. , Maccagni D. , Pentericci L. , Schaerer D. , Talia M. , Tasca L. A. M. , Zucca E.
Published: February 2017

Context. The study of statistically significant samples of star-forming dwarf galaxies (SFDGs) at different cosmic epochs is essential for the detailed understanding of galaxy assembly and chemical evolution. However, the main properties of this large population of galaxies at intermediate redshift are still poorly known.

Aims. We present the discovery and spectrophotometric characterization of a large sample of 164 faint (iAB~ 23–25 mag) SFDGs at redshift 0.13 ≤ z ≤ 0.88 selected by the presence of bright optical emission lines in the VIMOS Ultra Deep Survey (VUDS). We investigate their integrated physical properties and ionization conditions, which are used to discuss the low-mass end of the mass-metallicity relation (MZR) and other key scaling relations.

Methods. We use optical VUDS spectra in the COSMOS, VVDS-02h, and ECDF-S fields, as well as deep multi-wavelength photometry that includes HST-ACS F814W imaging, to derive stellar masses, extinction-corrected star-formation rates (SFR), and gas-phase metallicities of SFDGs. For the latter, we use the direct method and a Te-consistent approach based on the comparison of a set of observed emission lines ratios with the predictions of detailed photoionization models.

Results. The VUDS SFDGs are compact (median re~ 1.2 kpc), low-mass (M∗~ 107–109M⊙) galaxies with a wide range of star-formation rates (SFR(Hα) ~ 10-3–101M⊙/yr) and morphologies. Overall, they show a broad range of subsolar metallicities (12 +log (O/H) =7.26–8.7; 0.04 ≲Z/Z⊙≲ 1). Nearly half of the sample are extreme emission-line galaxies (EELGs) characterized by high equivalent widths and emission line ratios indicative of higher excitation and ionization conditions. The MZR of SFDGs shows a flatter slope compared to previous studies of galaxies in the same mass range and redshift. We find the scatter of the MZR is partly explained in the low mass range by varying specific SFRs and gas fractions amongst the galaxies in our sample. In agreement with recent studies, we find the subclass of EELGs to be systematically offset to lower metallicity compared to SFDGs at a given stellar mass and SFR, suggesting a younger starburst phase. Compared with simple chemical evolution models we find that most SFDGs do not follow the predictions of a “closed-box” model, but those from a gas-regulating model in which gas flows are considered. While strong stellar feedback may produce large-scale outflows favoring the cessation of vigorous star formation and promoting the removal of metals, younger and more metal-poor dwarfs may have recently accreted large amounts of fresh, very metal-poor gas, that is used to fuel current star formation.
Spectral and rotational properties of near-Earth asteroid (162173) Ryugu, target of the Hayabusa2 sample return mission
Authors: Perna D. , Barucci M. A. , Ishiguro M. , Alvarez-Candal A. , Kuroda D. , Yoshikawa M. , Kim M.-J. , Fornasier S. , Hasegawa S. , Roh D.-G. , Müller T. G. , Kim Y.
Published: February 2017

Context.The JAXA Hayabusa2 mission will perform the first ever sample return from a primitive asteroid. The target near-Earth asteroid (162173) Ryugu will be reached in mid-2018 and its samples will be returned to the Earth by the end of 2020.

Aims.We want to improve the current knowledge of the compositional and rotational properties of Ryugu, which are still presenting some uncertainties that might affect the mission operations and scientific return.

Methods.We acquired high-quality photometric time-series data with the FORS2 instrument at the Very Large Telescope of the European Southern Observatory (ESO-VLT, Chile). We also acquired four FORS2 visible spectra and three X-shooter spectra in the 0.35−2.15μm range, at different rotational phases.

Results.We obtained the currently highest-quality visual light-curve of Ryugu. A best solution of ~7.63 h is found for the rotational period, while a short-period solution (i.e.,P≈ 3.8 h) is ruled out by the clearly non-symmetric light-curve. The obtained spectra are generally similar and featureless, but present a drop-off of the reflectance at <0.45μm, suggesting the presence of aqueously altered minerals on Ryugu. The best meteorite analogs for Ryugu are represented by thermally altered CM carbonaceous chondrites.

Conclusions.Our new photometric data help to refine the target reference model used by the Hayabusa2 team for the mission preparation and implementation, improving our knowledge of Ryugu’s spin properties. Our new spectra constrain the compositional and geological context of the Ryugu’s surface in order to prepare the planning of mission observations and support the working group for the selection of possible landing and sampling sites.
Gesundheitskongress des Westens: Mit Gerald Hüther gegen Sektoren
Authors: Dorner Carola
Published: February 2017

Was erwartet Besucher auf dem Gesundheitskongress des Westens? kma sprach vorab mit Veranstalterin Ingrid Völker.
Auswirkung des KHSG: Zuerst trifft es orthopädische Leistungen
Authors: Bartels Claus , Helling Jan
Published: February 2017

Unter den neuen Bedingungen des Krankenhausstrukturgesetzes wird die Leistungsplanung für Kliniken deutlich komplizierter. 2017 sind unfallchirurgische, orthopädische aber auch neurochirurgische Kliniken besonders durch die Auswirkungen betroffen.
Weight in the First Year of Life: Associations with Maternal Prepregnancy Body Mass Index and Gestational Weight Gain—Findings from a Longitudinal Pregnancy Cohort
Authors: McPhie Skye , Skouteris Helen , Mattick Richard , Wilson Judy , Honan Ingrid , Allsop Steve , Burns Lucy , Elliott Elizabeth , Teague Samantha , Olsson Craig , Hutchinson Delyse
Published: February 2017

Objective To investigate the obesogenic influence of maternal prepregnancy body mass index (BMI) and gestational weight gain (GWG) on infant weight at birth and 12 months postpartum in an Australian general population sample.

Methods Data on 1,305 pregnant women were collected on prepregnancy BMI and GWG through maternal interview, on infant weight at birth through hospital records, and on infant weight 12 months postbirth through direct measurement. Relationships between prepregnancy, gestational weight exposures, and infant weight outcomes were assessed with and without adjustment for potential confounding.

Results We observed a 14 to 24 g increase in infant birth weight for every 1 kg increase in maternal weight (infant birth weight: β(BMI) = 0.014, p < 0.000; β(GWG) = 0.012, p < 0.000; and 12 months: β(BMI) = 0.018, p < 0.000; β(GWG) = 0.024, p < 0.000). Effects remained after adjustment for potential confounders (infant birth weight: β(BMI) = 0.014, p < 0.000; β(GWG) = 0.012, p < 0.001; and 12 months: β(BMI)= 0.017, p ≤ 0.033; β(GWG) = 0.023, p = 0.001). However, the effects observed were small, and there was no evidence that GWG mediated relationships between preconception BMI and infant weight.

Conclusion In a general population sample, there is a significant but not substantial observed relationship between maternal prepregnancy BMI and GWG and infant weight outcomes, suggesting a minor role for these factors at a population level.
Dringlichkeit von hausärztlichen Notfallbesuchen in Altenheimen
Authors: Bleckwenn Markus , Ahrens Sabrina , Schnakenberg Rieke , Weckbecker Klaus
Published: February 2017

Bisher gibt es keine einheitlichen Kriterien oder Standards für die Dringlichkeitseinstufung von Hausbesuchen. Aufgrund des demographischen Wandels werden insbesondere dringende Hausbesuche in Altenheimen zunehmen. In der URGENT-Studie stuften Ärzte und Pflegekräfte die Dringlichkeit von Notfallhausbesuchen in Seniorenpflegeheimen vor und nach dem Hausbesuch ein. Damit sollte erfasst werden, wie viele Notfallhausbesuche im Nachhinein als weniger dringend eingestuft werden und wie häufig Ärzte und Pflegende in ihrer Einschätzung übereinstimmen.

Im Rahmen einer prospektiven Beobachtungsstudie wurden Hausbesuche ausgewertet, die von den Hausärzten bei Anforderung als dringend eingestuft wurden. Nach der Durchführung der Heimbesuche stuften sowohl der Hausarzt als auch die verantwortliche Pflegefachkraft die Dringlichkeit des Heimbesuches von 0 (überhaupt nicht dringend) bis10 (sehr dringend) ein. Zusätzlich wurden die Uhrzeiten der Heimbesuchsanfragen bzw. Durchführung, sowie die Gründe für die Hausbesuche dokumentiert.

Es wurden 75 dringende Heimbesuche ausgewertet. Die Patienten waren im Durchschnitt 82 Jahre alt (65% weiblich). Die Hausbesuche wurden im Durchschnitt 2,5 Stunden nach ihrer Anforderung durchgeführt. Im Nachhinein stuften die Hausärzte die Notfallhausbesuche im Durchschnitt weniger dringend (5,7±2,7) als die Pflegekräfte (7,2±2,2) ein. 20% der Notfallhausbesuche (15 Fälle) stuften sowohl Ärzte als auch Pflegekräfte übereinstimmend als weniger dringend (0–5) ein.

Unsere Daten zeigen, dass bei der bisher nicht standardisierten Einschätzung der Dringlichkeit ein erheblicher Anteil der Hausbesuche falsch kategorisiert wird. In weiteren Studien ist zu prüfen, ob ein einheitlicher Score zur Dringlichkeitseinschätzung den Anteil dieser Fehleinsätze verringern und so die Effizienz der Notfallversorgung von Altenpflegeheimen verbessern könnte.
Antibiotikaresistenz: In welchen Handlungsfeldern muss mehr getan werden?
Authors: Sauskojus Hendrik , Wagner-Ahlfs Christian , Razum Oliver
Published: February 2017

Antibiotika werden seit Jahrzehnten erfolgreich zur Behandlung von Infektionskrankheiten eingesetzt. Die Entwicklung von Resistenzen ist hierbei ein natürlicher Vorgang. Mit dem weltweit kontinuierlich ansteigenden Antibiotika-Verbrauch wird dieser Vorgang jedoch stark beschleunigt. Schon jetzt sind Infektionskrankheiten wie die Tuberkulose oder Gonorrhoe oft nur noch schwer behandelbar. Auch nosokomiale Infektionen mit multiresistenten Keimen stellen inzwischen ein großes Problem für die Gesundheitsversorgung dar. Es wurden bereits mehrere Aktionspläne und Gegenmaßnahmen entwickelt, welche indes nur unzureichend umgesetzt werden und nicht alle auftretenden Probleme adressieren. Dies ist in verschiedenen Handlungsfeldern jedoch dringend erforderlich, sollen Antibiotika auch in Zukunft für eine erfolgreiche Infektionsbehandlung zur Verfügung stehen.
Influence of substrate on structural and transport properties of LaNiO3 thin films prepared by pulsed laser deposition
Authors: Cichetto L. , Sergeenkov S. , Diaz J. C. C. A. , Longo E. , Araújo-Moreira F. M.
Published: February 2017

We report the structural and transport properties of LaNiO3 thin films prepared by pulsed laser deposition technique. To understand the effects of film thickness, lattice mismatch and grain size on transport properties, various oriented substrates were used for deposition, including single-crystalline SrLaAlO4 (001), SrTiO3 (100) and LaAlO3 (100). To achieve a high quality LaNiO3 thin films, the vital parameters (such as laser fluence, substrate temperature, oxygen pressure, and deposition time) were optimized. The best quality films are found to be well textured samples with good crystalline properties.
Depletion attraction of sheet-like ion aggregates in low-dielectric ionomer melts
Authors: Lu Keran , Maranas Janna K. , Milner Scott T.
Published: February 2017

Ionomers are polymers in which an ionic group is covalently bonded to the polymer backbone. Ion aggregates in ionomers have morphologies that allow for the packing of the attached polymer backbone. Using ion-only coarse-grained molecular dynamics, we observe that string-like ion aggregates become flat and sheet-like at lower dielectric constants. A consequence of the changing morphology is that the sheet-like aggregates self-assemble to form ordered, lamellar structures. We use a simple thermodynamic model to demonstrate that depletion attraction mediated by small aggregates can explain the observed order. Our results suggest that depletion attraction can drive ions to form structures that have the size scale suggested by direct visualization, produce the commonly observed experimental correlation peak from X-ray and neutron scattering, and satisfy chain-packing constraints that have been demonstrated to be important in simulations.
Accurate ab initio dipole moment surfaces of ozone: First principle intensity predictions for rotationally resolved spectra in a large range of overtone and combination bands
Authors: Tyuterev Vladimir G. , Kochanov Roman V. , Tashkun Sergey A.
Published: February 2017

Ab initio dipole moment surfaces (DMSs) of the ozone molecule are computed using the MRCI-SD method with AVQZ, AV5Z, and VQZ-F12 basis sets on a dense grid of about 1950 geometrical configurations. The analytical DMS representation used for the fit of ab initio points provides better behavior for large nuclear displacements than that of previous studies. Various DMS models were derived and tested. Vibration-rotation line intensities of 16O3 were calculated from these ab initio surfaces by the variational method using two different potential functions determined in our previous works. For the first time, a very good agreement of first principle calculations with the experiment was obtained for the line-by-line intensities in rotationally resolved ozone spectra in a large far- and mid-infrared range. This includes high overtone and combination bands up to ΔV = 6. A particular challenge was a correct description of the B-type bands (even ΔV3 values) that represented major difficulties for the previous ab initio investigations and for the empirical spectroscopic models. The major patterns of various B-type bands were correctly described without empirically adjusted dipole moment parameters. For the 10 μm range, which is of key importance for the atmospheric ozone retrievals, our ab initio intensity results are within the experimental error margins. The theoretical values for the strongest lines of the ν3 band lie in general between two successive versions of HITRAN (HIgh-resolution molecular TRANsmission) empirical database that corresponded to most extended available sets of observations. The overall qualitative agreement in a large wavenumber range for rotationally resolved cold and hot ozone bands up to about 6000 cm−1 is achieved here for the first time. These calculations reveal that several weak bands are yet missing from available spectroscopic databases.
Convergence of high order perturbative expansions in open system quantum dynamics
Authors: Xu Meng , Song Linze , Song Kai , Shi Qiang
Published: February 2017

We propose a new method to directly calculate high order perturbative expansion terms in open system quantum dynamics. They are first written explicitly in path integral expressions. A set of differential equations are then derived by extending the hierarchical equation of motion (HEOM) approach. As two typical examples for the bosonic and fermionic baths, specific forms of the extended HEOM are obtained for the spin-boson model and the Anderson impurity model. Numerical results are then presented for these two models. General trends of the high order perturbation terms as well as the necessary orders for the perturbative expansions to converge are analyzed.
A new technique based on current measurement for nanoscale ferroelectricity assessment: Nano-positive up negative down
Authors: Martin Simon , Baboux Nicolas , Albertini David , Gautier Brice
Published: February 2017

In this paper, we propose a new procedure which aims at measuring the polarisation switching current at the nanoscale on ferroelectric thin films with the atomic force microscope tip used as a top electrode. Our technique is an adaptation of the so-called positive up negative down method commonly operated on large electrodes. The main obstacle that must be overcome to implement such measurement is the enhancement of the signal to noise ratio, in a context where the stray capacitance of the sample/tip/lever/lever holder system generates a dielectric displacement current several orders of magnitude higher than the current to be measured. This problem is solved by the subtraction of the displacement current through a reference capacitance. For the first time, we show an example of nanoscale positive up negative down measurement of the polarisation charge on a PbZrTiO3 thin film and compare the measured value with paraelectric samples. From the comparison with macroscopic measurement, we deduce the effective area of contact between the tip and the sample.
Stability properties of the steady state solutions of a non-neutral plasma diode when there is a uniform magnetic field along transverse direction
Authors: Kuznetsov V. I. , Pramanik Sourav , Gerasimenko A. B. , Chakrabarti Nikhil
Published: February 2017

The stability properties of a non-neutral plasma diode [Pramanik et al., Phys. Plasmas 23, 103105 (2016)] have been investigated for the stationary states taking arbitrary value of the neutralization parameter. A constant magnetic field is also assumed to be applied externally along the transverse direction. The (η, ε)-diagram technique is used to study the stability features of all types of solutions with respect to small aperiodic perturbations. Employing the first order perturbation theory, a relevant dispersion relation has been derived and analyzed for the regimes when electrons are not turned around by the magnetic field. These regimes of solutions belong to the “Normal C branch” and “C-overlap branch” of the “emitter field strength vs. diode gap”-diagrams. With the help of this dispersion relation, both aperiodic and oscillatory stability properties of such solutions have been presented.
Discrete- and finite-bandwidth-frequency distributions in nonlinear stability applications
Authors: Kuehl Joseph J.
Published: February 2017

A new “wave packet” formulation of the parabolized stability equations method is presented. This method accounts for the influence of finite-bandwidth-frequency distributions on nonlinear stability calculations. The methodology is motivated by convolution integrals and is found to appropriately represent nonlinear energy transfer between primary modes and harmonics, in particular nonlinear feedback, via a “nonlinear coupling coefficient.” It is found that traditional discrete mode formulations overestimate nonlinear feedback by approximately 70%. This results in smaller maximum disturbance amplitudes than those observed experimentally. The new formulation corrects this overestimation, accounts for the generation of side lobes responsible for spectral broadening, and results in disturbance representation more consistent with the experiment than traditional formulations. A Mach 6 flared-cone example is presented.
Manipulating and probing the polarisation of a methyl tunnelling system by field-cycling NMR
Authors: Zhang Bo , Abu-Khumra Sabah M. M. , Aibout Abdellah , Horsewill Anthony J.
Published: February 2017

In NMR the polarisation of the Zeeman system may be routinely probed and manipulated by applying resonant rf pulses. As with spin-1/2 nuclei, at low temperature the quantum tunnelling states of a methyl rotor are characterised by two energy levels and it is interesting to consider how these tunnelling states might be probed and manipulated in an analogous way to nuclear spins in NMR. In this paper experimental procedures based on magnetic field-cycling NMR are described where, by irradiating methyl tunnelling sidebands, the polarisations of the methyl tunnelling systems are measured and manipulated in a prescribed fashion. At the heart of the technique is a phenomenon that is closely analogous to dynamic nuclear polarisation and the solid effect where forbidden transitions mediate polarisation transfer between 1H Zeeman and methyl tunnelling systems. Depending on the irradiated sideband, both positive and negative polarisations of the tunnelling system are achieved, the latter corresponding to population inversion and negative tunnelling temperatures. The transition mechanics are investigated through a series of experiments and a theoretical model is presented that provides good quantitative agreement.
Graphene contacts to a HfSe2/SnS2 heterostructure
Authors: Su Shanshan , Das Protik , Ge Supeng , Lake Roger K.
Published: February 2017

Two-dimensional (2D) heterostructures and all-2D contacts are of high interest for electronic device applications, and the SnS2/HfSe2 bilayer heterostructure with graphene contacts has some unique, advantageous properties. The SnS2/HfSe2 heterostructure is interesting because of the strong intermixing of the two conduction bands and the large work function of the SnS2. The band lineup of the well separated materials indicates a type II heterostructure, but the conduction band minimum of the SnS2/HfSe2 bilayer is a coherent superposition of the orbitals from the two layers with a spectral weight of 60% on the SnS2 and 40% on the HfSe2 for AA stacking. These relative weights can be either increased or reversed by an applied vertical field. A 3×3 supercell of graphene and a 2×2 supercell of SnS2/HfSe2 have a lattice mismatch of 0.1% and both the SnS2/HfSe2 conduction band at M and the graphene Dirac point at K are zone-folded to Γ. Placing graphene on the SnS2/HfSe2 bilayer results in large n-type charge transfer doping of the SnS2/HfSe2 bilayer, on the order of 1013/cm2, and the charge transfer is accompanied by a negative Schottky barrier contact for electron injection from the graphene into the SnS2/HfSe2 bilayer conduction band. Binding energies and the anti-crossing gaps of the graphene and the SnS2/HfSe2 electronic bands both show that the coupling of graphene to the HfSe2 layer is significantly larger than its coupling to the SnS2 layer. A tunneling Hamiltonian estimate of the contact resistance of the graphene to the SnS2/HfSe2 heterostructure predicts an excellent low-resistance contact.
A novel design of a scanning probe microscope integrated with an ultramicrotome for serial block-face nanotomography
Authors: Efimov Anton E. , Agapov Igor I. , Agapova Olga I. , Oleinikov Vladimir A. , Mezin Alexey V. , Molinari Michael , Nabiev Igor , Mochalov Konstantin E.
Published: February 2017

We present a new concept of a combined scanning probe microscope (SPM)/ultramicrotome apparatus. It enables “slice-and-view” scanning probe nanotomography measurements and 3D reconstruction of the bulk sample nanostructure from series of SPM images after consecutive ultrathin sections. The sample is fixed on a flat XYZ scanning piezostage mounted on the ultramicrotome arm. The SPM measuring head with a cantilever tip and a laser-photodiode tip detection system approaches the sample for SPM measurements of the block-face surface immediately after the ultramicrotome sectioning is performed. The SPM head is moved along guides that are also fixed on the ultramicrotome arm. Thereby, relative dysfunctional displacements of the tip, the sample, and the ultramicrotome knife are minimized. The design of the SPM head enables open frontal optical access to the sample block-face adapted for high-resolution optical lenses for correlative SPM/optical microscopy applications. The new system can be used in a wide range of applications for the study of 3D nanostructures of biological objects, biomaterials, polymer nanocomposites, and nanohybrid materials in various SPM and optical microscopy measuring modes.
Bending and growth of entrained air filament under converging and asymmetric rotational fields
Authors: Kumar Parmod , Das Arup K. , Mitra Sushanta K.
Published: February 2017

Here we have proposed the increase of the entrainment rate by extruding an air filament under the action of convergent but asymmetric rotational field. By varying the source speed and the diameter of rotational fields, we showed the bending of an air filament towards the higher strength direction of the asymmetric inertia. Interfacial profiles like bubble ejection from the air filament and non-collapsible entrainment with air accumulation in a stagnant zone are obtained in finite volume based numerical simulations, on gradual increase of average rotational fields. Physical understanding of bent interface profile reveals the presence of multiple stages in filament growth depending upon the inertia of surrounding medium. Accumulation of air in the stagnant zone is found to be more prominent in case of rotational speed based asymmetry in contrast to its counterpart having diametric asymmetry of imposing sources. Relative comparison between these two methods of producing asymmetric field showed faster growth of filament upon varying the source diameter, while keeping the speed same. In case of extreme retardation and enhancement of rotational asymmetry, film pinch off and formation of bubble train have been reported. The shape of ejected bubbles is governed by the inertia of the surrounding medium, and bubbles have taken elliptical shapes with their major axis aligned parallel to the adjacent velocity field.
Rotation forms and local Hamiltonian monodromy
Authors: Efstathiou K. , Giacobbe A. , Mardešić P. , Sugny D.
Published: February 2017

The monodromy of torus bundles associated with completely integrable systems can be computed using geometric techniques (constructing homology cycles) or analytic arguments (computing discontinuities of abelian integrals). In this article, we give a general approach to the computation of monodromy that resembles the analytical one, reducing the problem to the computation of residues of polar 1-forms. We apply our technique to three celebrated examples of systems with monodromy (the champagne bottle, the spherical pendulum, the hydrogen atom) and to the case of non-degenerate focus-focus singularities, re-obtaining the classical results. An advantage of this approach is that the residue-like formula can be shown to be local in a neighborhood of a singularity, hence allowing the definition of monodromy also in the case of non-compact fibers. This idea has been introduced in the literature under the name of scattering monodromy. We prove the coincidence of the two definitions with the monodromy of an appropriately chosen compactification.
Relaxation time and excess entropy in viscous liquids: Electric field versus temperature as control parameter
Authors: Richert Ranko
Published: February 2017

On the basis of adiabatic calorimetry data and results obtained from dielectric relaxation studies in the presence of a high static electric field, the effects of temperature and electric field induced changes of the excess entropy are compared for the same sample: supercooled cresolphthalein dimethylether. A field induced reduction of the excess entropy by 45 mJ K−1 mol−1 at constant temperature increases the structural relaxation time by 0.75%, while the same entropy change originating from lowering the temperature at constant field increases the time constant by 3.5%. Therefore, there is no simple link connecting excess entropy and relaxation time that is independent of the control parameter that is used to modify the entropy. A consequence is that the Adam-Gibbs approach does not provide a quantitative prediction for how the dynamics of liquids depend on the electric field, and, more generally, on excess entropy. This work compares the dynamics for temperature versus field induced changes of isobaric excess entropy, thereby eliminating previous uncertainties arising from isochoric versus isobaric conditions and from unknown relations between thermodynamic, excess, and configurational entropies.
Study of carrier energetics in ITO/P(VDF-TrFE)/pentacene/Au diode by using electric-field-induced optical second harmonic generation measurement and charge modulation spectroscopy
Authors: Otsuka Takako , Taguchi Dai , Manaka Takaaki , Iwamoto Mitsumasa
Published: February 2017

By using electric-field-induced optical second harmonic generation (EFISHG) measurement and charge modulation spectroscopy (CMS), we studied carrier behavior and polarization reversal in ITO/ poly(vinylidene fluoride trifluoroethylene) (P(VDF-TrFE))/pentacene/Au diodes with a ferroelectric P(VDF-TrFE) layer in terms of carrier energetics. The current-voltage (I–V) characteristics of the diodes showed three-step polarization reversal in the dark. However, the I–V was totally different under illumination and exhibited two-step behavior. EFISHG probed the internal electric field in the pentacene layer and accounted for the polarization reversal change due to charge accumulation at the pentacene/P(VDF-TrFE) interface. CMS probed the related carrier energetics and indicated that exciton dissociation in pentacene molecular states governed carrier accumulation at the pentacene/ferroelectric interface, leading to different polarization reversal processes in the dark and under light illumination. Combining EFISHG measurement and CMS provides us a way to study carrier energetics that govern polarization reversal in ferroelectric P(VDF-TrFE)/pentacene diodes.
Transition of electromagnetic wave by suddenly created magneto plasma
Authors: Kuo Spencer P.
Published: February 2017

The theory of the interaction of electromagnetic waves with a suddenly created magneto plasma is presented. It is shown that a linearly polarized wave propagating along the magnetic field is converted into a frequency upshifted two forward and two backward propagating waves; in each propagation direction, one is right hand circular polarization and the other one is left hand circular polarization. A static wiggler magnetic field is also produced. The combined forward and backward waves are amplitude modulated with rotating polarizations. The extent of the frequency upshift increases with the increases of the plasma density and the background magnetic field intensity. By increasing the background magnetic field, the required plasma density for the frequency upshift is reduced; consequently, the drop rate of the conversion efficiency with the increase in the frequency upshift of the combined forward wave can be reduced considerably; the conversion efficiency of the combined backward wave also increases.
Theoretical study on electron–phonon coupling factor and electron–ion nonequilibrium process in uranium
Authors: Li Zi , Wang Cong , Zhao Jize , Kang Wei , Zhang Ping
Published: February 2017

Rapid laser heating is an important experimental technique to achieve extreme conditions for uranium. Theoretical simulations of the electron–ion nonequilibrium energy relaxation after laser heating usually employ a two-temperature model using the thermal quantities of the electron heat capacity and the electron–phonon coupling factor as input parameters. Based on the first-principles calculations of the electron density of states and Eliashberg function, we theoretically determine the thermal quantities and their dependence on electron temperature and external pressure for uranium and revealed the connection between the thermal quantities and the electron density of states. The electron/ion temperature evolution was examined by employing the two-temperature model with the obtained thermal quantities. The time/temperature at the peak/equilibrium point of the temperature evolution curve was examined for different external pressures and different laser energy densities. We found that the approximation of a linear temperature-dependent electron heat capacity is acceptable at a low energy density, while at a high energy density, the electron temperature dependence of the electron heat capacity and the coupling factor from the first-principles calculations must be considered.
A radar-infrared bi-stealth structure based on metasurfaces
Authors: Zhong Shuomin , Jiang Wei , Xu Peipeng , Liu Taijun , Huang Jifu , Ma Yungui
Published: February 2017

In this work, the authors proposed a thin artificial structure that could give rise to the strong reduction of both radar wave reflection and infrared thermal emission. This is realized by the subtle combination of two specifically designed metasurface layers that control the infrared emission and microwave absorption, respectively. Our measurement shows that the fabricated sample could have wideband absorption from 3–8 GHz with attenuation efficiency larger than 90% up to incident angles of 30°. In the infrared atmosphere window, it gives a very low emission value of about 0.2. These results show that our sample is practically very promising for the application of a radar-infrared bi-stealth technology.
Rate-dependent extensions of the parametric magneto-dynamic model with magnetic hysteresis
Authors: Steentjes S. , Petrun M. , Glehn G. , Dolinar D. , Hameyer K.
Published: February 2017

This paper extends the parametric magneto-dynamic model of soft magnetic steel sheets to account for the phase shift between local magnetic flux density and magnetic field strength. This phase shift originates from the damped motion of domain walls and is strongly dependent on the microstructure of the material. In this regard, two different approaches to include the rate-dependent effects are investigated: a purely phenomenological, mathematical approach and a physical-based one.
Electrical detection of single magnetic skyrmion at room temperature
Authors: Tomasello Riccardo , Ricci Marco , Burrascano Pietro , Puliafito Vito , Carpentieri Mario , Finocchio Giovanni
Published: February 2017

This paper proposes a protocol for the electrical detection of a magnetic skyrmion via the change of the tunneling magnetoresistive (TMR) signal in a three-terminal device. This approach combines alternating spin-transfer torque from both spin-filtering (due to a perpendicular polarizer) and spin-Hall effect with the TMR signal. Micromagnetic simulations, used to test and verify such working principle, show that there exists a frequency region particularly suitable for this achievement. This result can be at the basis of the design of a TMR based read-out for skyrmion detection, overcoming the difficulties introduced by the thermal drift of the skyrmion once nucleated.
Electric field control of magnetic anisotropy in a Co/Pt bilayer deposited on a high-κ SrTiO3
Authors: Nakazawa S. , Obinata A. , Chiba D. , Ueno K.
Published: February 2017

The perpendicular magnetic anisotropy (PMA) of a Co (0.5 nm)/Pt (2.4 nm) bilayer film was electrostatically tuned using a high-κ dielectric, SrTiO3, with a back-gating configuration. The Co film was directly deposited onto a SrTiO3 (001) substrate and capped by a Pt layer. The coercivity was enhanced (reduced) by applying a positive (negative) gate bias. The efficiency of the PMA energy modulation by the electric field was determined to be 1300–23 100 fJ/V m, which is 1–3 orders of magnitude higher than the efficiencies obtained in previous studies. The superior efficiency of this system is most likely attributable to the large dielectric constant of the SrTiO3 gate insulator and could be evidence that the PMA energy modulation is induced by charge accumulation.
Effect of epitaxial strain and lattice mismatch on magnetic and transport behaviors in metamagnetic FeRh thin films
Authors: Xie Yali , Zhan Qingfeng , Shang Tian , Yang Huali , Wang Baomin , Tang Jin , Li Run-Wei
Published: February 2017

We grew 80 nm FeRh films on different single crystals with various lattice constants. FeRh films on SrTiO3 (STO) and MgO substrates exhibit an epitaxial growth of 45° in-plane structure rotation. In contrast, FeRh on LaAlO3 (LAO) displays a mixed epitaxial growth of both 45° in-plane structure rotation and cube-on-cube relationships. Due to the different epitaxial growth strains and lattice mismatch values, the critical temperature for the magnetic phase transition of FeRh can be changed between 405 and 360 K. In addition, the external magnetic field can shift this critical temperature to low temperature in different rates for FeRh films grown on different substrates. The magnetoresistance appears a maximum value at different temperatures between 320 and 380 K for FeRh films grown on different substrates.
The high squareness Sm-Co magnet having Hcb=10.6 kOe at 150°C
Authors: Machida Hiroaki , Fujiwara Teruhiko , Kamada Risako , Morimoto Yuji , Takezawa Masaaki
Published: February 2017

The relationship between magnetic properties and magnetic domain structures of Sm(Fe, Cu, Zr, Co)7.5 magnet was investigated. The developed Sm-Co magnet, which is conducted homogenization heat treatment at ingot state, high temperature short time sintering and long time solid solution heat treatment showed the maximum energy product, [BH]m of 34.0 MGOe and the coercivity, Hcb of 11.3 kOe at 20°C respectively. Moreover, Hcb of 10.6 kOe at 150°C was achieved. Heat treated ingot has clear 1-7 phase in mother phase from optical microscope observation. Kerr effect microscope with magnetic field applied was used to investigate magnetic domain structure. Reverse magnetic domains were generated evenly but generation of them from inside grain were not observed. Cell structure was observed by scanning transmission electron microscope and composition analysis was conducted by energy dispersive X-ray spectroscopy. Cell size was approximately 150 ∼ 300 nm, Fe and Cu were clearly separated and concentrated to 2-17 phase and 1-5 phase respectively. Moreover, Cu concentration went up to 40 at% in 1-5 phase. That means the gap of domain wall energy between 1-5 phase and 2-17 phase was increased due to microstructure control by conducting heat treatment for compositional homogeneity.
Transition Metal Thiocyanate Complexes of Picolylcyanoacetamides
Authors: Prananto Yuniar P. , Urbatsch Aron , Moubaraki Boujemaa , Murray Keith S. , Turner David R. , Deacon Glen B. , Batten Stuart R.
Published: February 2017

A variety of transition metal complexes involving picolylcyanoacetamides (pica = NCCH2CONH-R; R = 2-picolyl- (2pica), 3-picolyl- (3pica), 4-picolyl- (4pica)) and thiocyanate have been synthesised and their solid-state structures have been determined. The complexes were all obtained from reactions between the corresponding metals salts and pica ligands with sodium thiocyanate under ambient conditions. Both 3pica and 4pica coordinate to the metal solely through the nitrogen atom of the picolyl group and form discrete tetrahedral [M(NCS)2(pica)2] (3pica; M = Mn, Zn; 4pica; M = Co) and octahedral [M(NCS)2(3pica)4] (M = Co, Fe, Ni) complexes. In addition, one-dimensional N,S-thiocyanate-bridged coordination polymers poly-[M(µ-NCS)2(pica)2] (3pica; M = Cd; 4pica; M = Co, Cd) were obtained. The ligand 2pica gave the discrete octahedral complexes [Co(NCS)2(2pica)2] and [Cd(NO3)2(2pica)2] in which 2pica chelates in a bidentate fashion through its picolyl and carbonyl groups. Magnetic susceptibility measurements on the cobalt(ii) complexes were performed and showed short-range antiferromagnetic coupling for the [Co(NCS)2(4pica)2]n 1D polymer.