bluuebunny/crossref_metadata_2025 huggingface dataset:
Simultaneous characterization of cross- and in-plane thermal transport in insulator patterned by directionally aligned nano-channels
Authors: Chauhan Vinay S. , Abdullaev Azat , Utegulov Zhandos , O’Connell Jacques , Skuratov Vladimir , Khafizov Marat
Published: January 2020

Anisotropic thermal transport behavior was investigated in a single crystal sapphire patterned by vertically aligned few-nanometer diameter and several micrometer long cylindrical ion tracks. These ion tracks were introduced by exposing the sapphire to energetic ions of xenon accelerated to 167 MeV with fluences ranging from 1012 to 1014 ions/cm2. It was found that, in the low ion-track density regime, cross-plane thermal conductivity is larger, whereas in the high track density regime, the trend reverses and in-plane conductivity becomes larger. The crossover between these regimes is attributed to the interplay between phonon scattering with ion track boundaries and phonon confinement effects. In the low track density regime, the material is described by bulk phonon dispersion and anisotropy in thermal transport is attributed to the aligned nature of tracks that effectively reduce the mean free path of phonons traveling in the in-plane direction more than in the cross-plane direction. In the high-density regime, larger conductivity reduction in the cross-plane direction is consistent with previous observations, where the anisotropic reduction in thermal conductivity is owed to the anisotropic reduction of acoustic velocity caused by phonon confinement. Our results are further supported by an analytical model describing phonon mediated thermal transport.
Charge transfer dynamics of the CdTe quantum dots fluorescence quenching induced by ferrous (II) ions
Authors: Hao Licai , Chen Xuanhu , Liu Dongyang , Bian Yue , Zhao Weikang , Tang Kun , Zhang Rong , Zheng Youdou , Gu Shulin
Published: January 2020

Size dependence of glutathione capped CdTe quantum dots (GSH-CdTe QDs) on the sensitivity and selectivity in the fluorometric detection of ferrous (II) ions (Fe2+) has been systematically investigated. Smaller-size QDs show higher sensitivity in the detection of Fe2+, resulting in higher quenching efficiency and red shift of the fluorescence peak of QDs. Stern–Volmer plots indicate that the charge transfer model can be employed to account for the observed fluorescence quenching effect. Fe2+ is bound to the surface of QDs by GSH and excited electrons are transferred from QDs to Fe2+, which facilitates a nonradiative recombination process and a decrease in the PL efficiency. In addition, the results from time resolved photoluminescence and a confocal scanning fluorescence microscope have shown that smaller-size QDs have a faster decrease in the fluorescence lifetime compared with that of larger-size QDs with Fe2+ addition, suggesting that the fast charge transfer in smaller-size QDs should be responsible for the observed fluorescence quenching effect. This Letter provides a comprehensive understanding of the mechanism of the fluorescence for the CdTe QDs quenched by Fe2+.
Interlayer exchange coupling and interface magnetic anisotropy with crossed in-plane and perpendicular magnetic anisotropies
Authors: Koizumi Hiroki , Hagihara Michio , Kobayashi Soki , Yanagihara Hideto
Published: January 2020

We investigated interlayer exchange coupling (IEC) and interface magnetic anisotropy (Ki) between two ferromagnetic layers with crossed in-plane and perpendicular magnetic anisotropies separated by a non-magnetic spacer by using the anomalous Hall effect (AHE). The sample consisted of a Co0.75Fe2.25O4 layer with perpendicular magnetic anisotropy and a Fe layer with in-plane anisotropy, separated by a MgO layer with variable thickness. Since Co0.75Fe2.25O4 and MgO are insulators, the AHE signal only reflects the magnetization process of Fe. From this, we determined both IEC and Ki. A strong antiferromagnetic IEC was confirmed between Co0.75Fe2.25O4 and Fe. The strongest IEC of −1.1 mJ/m2 was observed for directly coupled Fe and Co0.75Fe2.25O4 for which Ki was −1.1 mJ/m2.
Plasma-assisted molecular beam epitaxy of NiO on GaN(00.1)
Authors: Budde Melanie , Remmele Thilo , Tschammer Carsten , Feldl Johannes , Franz Philipp , Lähnemann Jonas , Cheng Zongzhe , Hanke Michael , Ramsteiner Manfred , Albrecht Martin , Bierwagen Oliver
Published: January 2020

The growth of NiO on GaN(00.1) substrates by plasma-assisted molecular beam epitaxy under oxygen-rich conditions was investigated at growth temperatures between 100°C and 850°C. Epitaxial growth of NiO(111) with two rotational domains, with epitaxial relation NiO(11¯0)‖GaN(11.0) and NiO(101¯)‖GaN(11.0), was observed by X-ray diffraction and confirmed by in situ reflection high-energy electron diffraction as well as transmission electron microscopy (TEM) and electron backscatter diffraction. With respect to the high lattice mismatch of 8.1% and a measured low residual tensile layer strain, growth by lattice matching epitaxy or domain-matching epitaxy is discussed. The morphology measured by atomic force microscopy showed a grainy surface, probably arising from the growth by columnar rotational domains visible in TEM micrographs. The domain sizes measured by AFM and TEM increase with the growth temperature, indicating an increasing surface diffusion length. Growth at 850°C, however, involved local decomposition of the GaN substrate that leads to an interfacial β-Ga2O3(2¯01) layer and a high NiO surface roughness. Raman measurements of the quasiforbidden one-phonon peak indicate increasing layer quality (decreasing defect density) with increasing growth temperature.
Second harmonic response of magnetic nanoparticles under parallel static field and perpendicular oscillating field for magnetic particle imaging
Authors: Ota Satoshi , Nishimoto Kizuku , Yamada Tsutomu , Takemura Yasushi
Published: January 2020

The second harmonic signal of a magnetic nanoparticle in an oscillating magnetic field was enhanced, by applying a static bias field. To promote the second harmonic signal, the oscillating field was applied perpendicular to the signal detection and static bias field. The second harmonic signal, detected in this study, was significantly higher than that of the third harmonic signal detected without a static bias field. It was also significantly higher than that of the second harmonic signal with the static bias and oscillating drive field parallel to the signal detection direction, as in the conventional setup of previous studies. The second harmonic signal dependence on the intensity of the static bias field showed that the signal intensity had a maximal value beyond the field free point (FFP), despite the maximal third harmonic existing within the FFP. In our system, the odd numbered harmonics, including the fundamental harmonic, were no longer detected. This is because the fundamental signal had a frequency twice that of the applied oscillating field. This may contribute to a significantly higher signal to noise ratio for magnetic particle imaging (MPI). In addition, the full width at half maximum associated with MPI resolution was constant with drive field amplitude, which contributes to high signal intensity and resolution, concurrently.
STT-MRAM error correction technology based on LDPC coding
Authors: Zhang Xue , Liu Jianbin , Jiang Yanfeng
Published: January 2020

Spin transfer magnetoresistive random access memory (STT-MRAM) shows potential applications with the properties of non-volatility, low power consumption and high write/read speed. With the maturity of the STT-MRAM process, it has gradually entered the mass production stage. Reliability will be an important factor limiting the development of this device. Error correction technology is highly required to be developed on this specific memory circuit. In this paper, a combination of low density parity check (LDPC) is used on STT-MRAM, in which the encoding constructs a no 4-girth check matrix. In its fulfillment, the decoded method combines soft decision and hard decision. The simulation results demonstrate that the LDPC shows promising application scenario for STT-MRAM error correction, especially for large-capacity storage arrays.
Magnetic properties of polycrystalline Y-type hexaferrite Ba2-xSrxNi2(Fe1-yAly)12O22 using Mössbauer spectroscopy
Authors: Kim Jeonghun , Choi Hyunkyung , Kim Chul Sung
Published: January 2020

Synthesis of the polycrystalline Ba2-xSrxNi2(Fe1-yAly)12O22 (x = 0.0, 1.5, y = 0.00, 0.01, and 0.03) was accomplished by employing the polymerizable complex method. The samples were investigated for the crystallographic and magnetic properties by x-ray diffraction (XRD), vibrating sample magnetometer (VSM), and Mössbauer spectrometer. Based on the results of the refined XRD patterns, all samples were confirmed to have a rhombohedral structure with space group R-3m. Moreover, six distinguished sublattices were identified, which were four octahedral sites (18hVI, 3bVI, 6cVI, and 3aVI) and two tetrahedral sites (6cIV*, 6cIV). The lattice constant of a0 and c0 decrease via Sr, Al substitution because the ionic radius of Sr2+ (1.12 Å) is smaller than that of Ba2+ (1.34 Å), and the ionic radius of Al3+ (0.535 Å) is smaller than that of Fe3+ (0.645 Å). The zero-field-cooled (ZFC) measurement was applied at 100 Oe between 4.2 and 295 K and it revealed the spin transition temperature (TS). Substitution of Sr ions increased TS. Al ions were further substituted after the substitution of Sr ions, and TS increased above room temperature. The Mössbauer spectra fit six distinguish sublattices: 18hVI, 3bVI, 6cIV, 6cIV*, 6cVI, and 3aVI. The isomer shift of all samples indicated that the charge state of Fe ions is Fe3+. The Mössbauer spectra obtained with respect to temperature change confirmed the changes in the magnetic hyperfine field curves at Ts.
Heteroatom doping effects on interaction of H2O and CeO2 (111) surfaces studied using density functional theory: Key roles of ionic radius and dispersion
Authors: Murakami Kota , Ogo Shuhei , Ishikawa Atsushi , Takeno Yuna , Higo Takuma , Tsuneki Hideaki , Nakai Hiromi , Sekine Yasushi
Published: January 2020

Understanding heteroatom doping effects on the interaction between H2O and cerium oxide (ceria, CeO2) surfaces is crucially important for elucidating heterogeneous catalytic reactions of CeO2-based oxides. Surfaces of CeO2 (111) doped with quadrivalent (Ti, Zr), trivalent (Al, Ga, Sc, Y, La), or divalent (Ca, Sr, Ba) cations are investigated using density functional theory (DFT) calculations modified for onsite Coulomb interactions (DFT + U). Trivalent (except for Al) and divalent cation doping induces the formation of intrinsic oxygen vacancy (Ovac), which is backfilled easily by H2O. Partially OH-terminated surfaces are formed. Furthermore, dissociative adsorption of H2O is simulated on the OH terminated surfaces (for trivalent or divalent cation doped models) and pure surfaces (for Al and quadrivalent cation doped surfaces). The ionic radius is crucially important. In fact, H2O dissociates spontaneously on the small cations. Although a slight change is induced by doping as for the H2O adsorption energy at Ce sites, the H2O dissociative adsorption at Ce sites is well-assisted by dopants with a smaller ionic radius. In terms of the amount of promoted Ce sites, the arrangement of dopant sites is also fundamentally important.
Morphogenetic and structural characteristics of Urochloa species under inoculation with plant-growth-promoting bacteria and nitrogen fertilisation
Authors: Duarte Camila Fernandes Domingues , Cecato Ulysses , Hungria Mariangela , Fernandes Henrique Jorge , Biserra Thiago Trento , Galbeiro Sandra , Toniato Anny Karulinny Barroso , da Silva Diogo Rodrigues
Published: January 2020

Ineffective management of pastures still constitutes the main problem in the Brazilian livestock industry, in which recovery of soil fertility is a determinant for soil restoration. In this context and in combination with the adoption of sustainable technologies, the use of plant-growth-promoting bacteria (PGPB) may represent an alternative to the use of chemical fertilisers that would reduce costs and environmental impacts. In this study, morphogenetic and structural characteristics were evaluated in three Urochloa (syn. Brachiaria) varieties. Urochloa is a genus that is present in the most degraded pastures in Brazil. The three varieties were inoculated with five PGPB (Azospirillum brasilense Ab-V5 and Ab-V6, Pseudomonas fluorescens CCTB 03 and ET76, and Pantoea ananatis AMG521) and treated with different doses of nitrogen (N) fertiliser (0, 50 and 100 kg N ha–1) in pots filled with sandy soil under greenhouse conditions. In general, for Marandu grass U. brizantha cvv. BRS Paiaguás and Xaraés, the best performances for leaf and stem elongation rates and number of basal tillers were obtained with strains CCTB 03 and AMG521. For U. ruziziensis, the best performance in the duration and rate of renewal of leaves and leaf senescence was observed with strains AMG521, Ab-V5 and Ab-V6. This result indicated the specificity of the effects of bacterial strains on different genotypes of Urochloa. Differences in the interactions between PGPB and N fertilisation were also verified. In U. brizantha, interaction effects were additive, whereas in U. ruziziensis, they were competitive. The results indicate the feasibility of inoculation of Urochloa with elite strains of PGPB that positively affect the production of forage biomass and allow reductions in N fertiliser usage.
Nitrogen fertilisation influences low CO2 effects on plant performance
Authors: Duarte André G. , Longstaffe Fred J. , Way Danielle A.
Published: January 2020

Low atmospheric CO2 conditions prevailed for most of the recent evolutionary history of plants. Such concentrations reduce plant growth compared with modern levels, but low-CO2 effects on plant performance may also be affected by nitrogen availability, since low leaf nitrogen decreases photosynthesis, and CO2 concentrations influence nitrogen assimilation. To investigate the influence of N availability on plant performance at low CO2, we grew Elymus canadensis at ambient (~400 μmol mol–1) and subambient (~180 μmol mol–1) CO2 levels, under four N-treatments: nitrate only; ammonium only; a full and a half mix of nitrate and ammonium. Growth at low CO2 decreased biomass in the full and nitrate treatments, but not in ammonium and half plants. Low CO2 effects on photosynthetic and maximum electron transport rates were influenced by fertilisation, with photosynthesis being most strongly impacted by low CO2 in full plants. Low CO2 reduced stomatal index in half plants, suggesting that the use of this indicator in paleo-inferences can be influenced by N availability. Under low CO2 concentrations, nitrate plants discriminated more against 15N whereas half plants discriminated less against 15N compared with the full treatment, suggesting that N availability should be considered when using N isotopes as paleo-indicators.
Electron number density measurements in nanosecond repetitively pulsed discharges in water vapor at atmospheric pressure
Authors: Sainct Florent P , Urabe Keiichiro , Pannier Erwan , Lacoste Deanna A , Laux Christophe O
Published: January 2020

This article reports on experiments in a nonequilibrium plasma produced by nanosecond repetitively pulsed (NRP) spark discharges in water vapor at 450 K and atmospheric pressure. The objective is to determine the electron number density in the post-discharge, with spatial and temporal resolution, to gain a better understanding of the discharge development and chemical kinetics. Electron number densities were measured in water vapor from the broadenings and shifts of the H
α
and H
β
lines of the hydrogen Balmer series and of the atomic oxygen triplet at 777 nm. For an average reduced electric field of about 150 Td, high electron densities up to 3 × 1018 cm−3 are measured at the cathode, up to 5 × 1017 cm−3 at the anode, and up to 4 × 1016 cm−3 in the interelectrode gap. The high density near the electrodes is attributed to ionization enhancement and secondary electron emission due to the high electric field in the plasma sheath. In the middle of the inter-electrode gap, we show that the electron density mainly decays by electron attachment reactions. The dissociation fraction of water vapor is estimated to be around 2% in the middle of the gap.
Enhancement of ultrafast photoluminescence from deformed graphene studied by optical localization microscopy
Authors: Chen En-Xiang , Cheng Hao-Yu , Chen Zheng-Gang , Chen Wei-Liang , Kataria Monika , Chang Yu-Ming , Chen Yang-Fang , Su Wei-Bin , Lin Kung-Hsuan
Published: January 2020

By using localization techniques, we demonstrated that the morphology of a 2D material in three dimensions can be optically obtained with nanometer precision in z-axis. This technique provides a convenient method to study the correlation between the optical properties and the morphology of 2D materials for the same area. We utilized optical localization microscopy to directly study the correlation between the ultrafast photoluminescence and the morphology of graphene. We observed enhancement of the ultrafast photoluminescence from the deformed graphene. In comparison to the planar graphene, the enhancement factor of ultrafast photoluminescence could be up to several times at the highly curved region. We found that the intensity of photoluminescence from the uniaxially rippled graphene depends on the polarization of excitation light. Furthermore, Raman spectroscopy was used to measure the strain distribution. Pump–probe measurements were conducted to reveal the carrier dynamics. From the experimental results, two mechanisms were confirmed to mainly account for the enhancement of ultrafast photoluminescence from the deformed graphene. One is the deformation-induced strain increases the absorption of graphene. The other is the prolonged carrier relaxation time in the curved graphene.
Effect of different coupling agents in the doping of graphite oxide with 3–3′ diaminobenzidine: textural, structural and electrical properties
Authors: Cervantes-Cuevas H , Jiménez-Hernández M , Chavez-Esquivel G , Acosta Dwight , Tavizon-Pozos J A , Santolalla-Vargas C E , Talavera-López A
Published: January 2020

The doping reactions of graphite oxide (GO) with 3-3′-diaminobenzidine (DAB) were studied using N, N′-dicyclohexylcarbodiimide (DCC), cyanuric chloride (CC) and hexafluorophosphate (HATU) as coupling agents. The bifunctionality of the coupling agents aid to interact GO functional groups with amino groups of DAB without being part of the final product. The doped materials (d-GO) and GO were characterized by thermogravimetric analysis, x-ray diffraction, FTIR/Raman spectroscopy, x-ray photoelectron, high-resolution electron microscopy and cyclic voltammetry. The GO-HATU material was more thermally stable than other graphitic material, with at 10% weight loss at 300 °C, this thermal stability is related to a more difficult intramolecular physisorbed water removal process than the other d-GO materials. GO-CC and GO-HATU materials presented 8.2 and 8.0 Å of interlayer spacing, which was associated with a good oxidation-doping process. Besides, these two materials showed modifications in the vibrations by FTIR technique, corresponding to epoxy and hydroxyl groups of the GO being more susceptible to react with the amino groups. Moreover, I

D
/I

G
ratio calculated by Raman Spectroscopy presents the following trend 0.70, 0.94, 0.97 and 1.04 for GO, GO-CC, GO-DCC and GO-HATU, respectively, this increase is related with a major disorder during the doping process. XPS analysis shows C–N and N=C bands for high resolution of C 1s and N 1s, respectively, for d-GO materials. This possibly suggests the formation of benzimidazoles during the oxidation-doping process, this generates a similar -non-lattice and -lattice oxygen amount for O 1s related to crosslinking between the functional groups of GO and DAB which improve the electronic mobility between the surface and the bulk of the final graphitic material. Finally, the obtained d-GO materials were investigated as a working electrode for electrochemical capacitors and all of them showed typical capacitive behaviour.
Fabrication of Ananas comosus leaf extract modified titanium dioxide nano bio adsorbent for the sequestration of basic dye from aqueous phase: equilibrium and kinetic studies
Authors: Fakhar Nida , Siddiqi Weqar Ahmad , Khan Tabrez Alam , Siddiqui Mohammad Fuzail
Published: January 2020

A novel, titanium dioxide nano bio-adsorbent (TiO2L) based on Ananas comosus leaf extract was developed by sol-gel route and was subsequently used to decolorize toxic non-biodegradable basic dye Victoria blue (VB) from the aqueous solution. Several techniques were used to characterize the synthesized bio-adsorbent like XRD, FTIR, SEM-EDX and TEM to observe physio-chemical changes and adsorption interactions. The impact of process parameters on the adsorption behavior of TiO2L towards VB were comprehensively studied and the optimized conditions were initial dye concentration (50 mg L−1), dose (1.8 g L−1), contact time (40 min), and pH (6) of the solution. Different isotherm and kinetic models were used to analyze the equilibrium data among which Langmuir model appropriately fitted the equilibrium data based on high R2 (0.994) and pseudo second order described the reaction kinetics of VB adsorption onto the adsorbent. The maximum adsorption capacity was found to be 83 mg g−1. Dye loaded adsorbent was regenerated and used for 3 cycles without subsequent loss in its efficiency. Thus, economic feasibility, environmentally friendly, better sorption capacity and regeneration potential, validates TiO2L as a potential adsorbent for VB from wastewater.
Facile synthesis of CdS Quantum dots for QDSSC with high photo current density
Authors: Archana T , Vijayakumar K , Subashini G , Grace A Nirmala , Arivanandhan M , Jayavel R
Published: January 2020

Environment-friendly and cost effective green CdS Quantum Dots (QDs) are synthesized using Azadirachta Indica extract as a novel non-toxic stabilizing agent and to excogitate its light harvesting potentiality for QD Sensitized Solar Cells (QDSSCs). The effect of different configuration of green CdS based QDSSCs viz (i) different phase of TiO2 photoanodes (ii) with and without ZnS passivating layer (iii) with Platinum counter electrodes (CE) and (iv) CuS CE have been investigated. Despite tralatitious SILAR CdS based QDSSC showed better efficiency (1.93%) than green CdS based QDSSC (0.77%), the later unveil higher photocurrent density (10.61 mA) possibly due to effective encapsulation of Azadirachta Indica which suppresses the surface defects in green CdS QDs favoring the transport of photo generated carriers. The work facilitate scope for cost effective and environment-friendly green synthesized CdS QDs that significantly modulated photovoltaic properties of QDs based solar cells in an inviolable condition.
Synthesis and electrochemical performance of ropelike LiNi0.8Co0.15Al0.05O2 fiber with nano-building blocks
Authors: Zhang Linsen , Zhao Zhenjiang , Li Xiaofeng , Fang Hua , Wang Lixia , Song Yanhua , Jia Xiaodong
Published: January 2020

A ropelike LiNi0.8Co0.15Al0.05O2 (NCA) fiber with superior rate capability and cycling stability was successfully synthesized via electrospinning and sintering as a cathode material for Li-ion batteries. The NCA fiber that exhibited excellent electrochemical performance as a cathode for Li-ion batteries was stacked and assembled from numerous nanoparticles. The NCA fiber delivered a high reversible capacity of 206.4 mAh g−1 at 0.1 C, and maintained 75% capacity retention after 100 cycles at 1 C. The high rate capability and outstanding cyclic stability were due to the ropelike fiber structure that shorten the Li+ diffusion path, improved the Li+ diffusion coefficient, and maintained the fiber structure during cycling.
Effect of processing on the properties and morphology of MWCNT-polymer networks
Authors: Watt Morgan R , Gerhardt Rosario A
Published: January 2020

The objective of this study was to determine the effect of processing on the electrical properties and microstructure of MWCNTs/PMMA nanocomposites made by compression molding. Three different mixing methods were used: mechanical, solution, and melt mixing of the same starting materials. The composite microstructures were found to be segregated, agglomerated, and randomly distributed respectively. Electrical property measurements indicate that the mechanically mixed composites have the lowest percolation threshold of 0.05 phr (0.028 vol% MWCNT). Melt mixed composites have the highest percolation threshold of 4 phr (2.161 vol% MWCNT) while solution mixed composites have a percolation threshold of 2 phr (1.102 vol% MWCNT). These results indicate that the segregated microstructure allows for the CNTs to form a percolated network through the composite more easily than the other two methods. Fitted equivalent circuits to the measured impedance spectra show that after percolation the CNTs dominate the electrical properties as represented by an increase in the number of inductance circuit elements. Before or at percolation, the presence of PMMA plays a stronger role in the circuit. This article is novel in that this is the first study where direct comparison of the properties and microstructure of composites fabricated utilizing three different mixing methods using the same source materials can be made.
Fabrication of lead-bismuth titanate borosilicate glass ceramics and dielectric characteristics doped with GNPs
Authors: Madheshiya Abhishek , Gautam Chandkiram , Srivastava Kamal K
Published: January 2020

Different compositions (x) of lead-bismuth titanate borosilicate (PBTB) glasses have been synthesized using a conventional melt-quenching method in the compound 55[(PbxBi1−x)TiO3]−44[2SiO2.B2O3], (x = 0.0, 0.3, 0.5, 0.7 and 1.0) mixed with 1 mol % of graphene nanoplatelets (GNPs). XRD analysis exhibited the synthesis of clear PBTB glasses which confirmed the amorphous nature. Synthesized glasses have been converted into glass-ceramics (GCs) using a differential thermal analysis (DTA) results to understand the crystallization mechanism. XRD results described the crystalline behavior of GC samples and distinct phase formation. The surface morphology of the GCs was analyzed using a scanning electron microscope (SEM). Energy dispersive X-ray analysis (EDAX) have been also performed to verify the elemental composition of the GC sample, PBTG0.5735 F (x = 0.5). The variation in relative dielectric constant (ε
r) and dissipation factor (D) by increasing temperatures was obtained at different frequencies. The GC sample PTG1.0746 F (x = 1.0) showed a maximum value of dielectric constant among all glass ceramic samples.
Electronic and optical behaviour of lanthanum doped CaTiO3 perovskite
Authors: Rizwan Muhammad , Usman Zahid , Shakil Muhammad , Gillani S S A , Azeem S , Jin H B , Cao C B , Mehmood Rana Farhat , Nabi Ghulam , Asghar Muhammad Adnan
Published: January 2020

To improve the efficiency of perovskite based solar cells, doping of heavier elements in Perovskite materials (ABX3) can modulate its electronic and optical properties significantly. Thus it is important to understand the possible microscopic origin of the band gap modification and optical enhancement after heavier element doping using first-principles studies. Here we investigate the effect of La doping, while substituting the Ca atom, on the electronic and optical properties in CaTiO3 perovskite material using generalized gradient approximation within density functional theory. We observe a decrease in lattice constants and bond lengths in LaxCa1−xTiO3, mainly due to re-distribution of electronic charge density between La and Oxygen, as confirmed by charge density contour. We further notice a widening of electronic band gap and an upward shift of Fermi level into the conduction band, thus characterizing LaxCa1−xTiO3 as an n-type material. DOS diagram attributes this shift mainly due to the appearance of La p-DOS and d-DOS and their repulsion with N p-DOS, when La enters into the host lattice at Ca site. Investigation of optical properties upon La Doping in CaTiO3 exhibits further shifting of polarization and refractive index to lower values as compared to its pure counterpart, due to dominating semiconducting behavior and hence one observes a blue shift in absorption and reflection spectrum accordingly. Energy loss function is found to be consistent with absorption and extinction coefficient measured in case of LaxCa1−xTiO3. All these results are found to be consistent with the existing experimental and first-principles studies.
Testing fuel cell catalysts under more realistic reaction conditions: accelerated stress tests in a gas diffusion electrode setup
Authors: Alinejad Shima , Inaba Masanori , Schröder Johanna , Du Jia , Quinson Jonathan , Zana Alessandro , Arenz Matthias
Published: January 2020

Gas diffusion electrode (GDE) setups have very recently received increasing attention as a fast and straightforward tool for testing the oxygen reduction reaction (ORR) activity of surface area proton exchange membrane fuel cell (PEMFC) catalysts under more realistic reaction conditions. In the work presented here, we demonstrate that our recently introduced GDE setup is suitable for benchmarking the stability of PEMFC catalysts as well. Based on the obtained results, it is argued that the GDE setup offers inherent advantages for accelerated degradation tests (ADT) over classical three-electrode setups using liquid electrolytes. Instead of the solid–liquid electrolyte interface in classical electrochemical cells, in the GDE setup a realistic three-phase boundary of (humidified) reactant gas, proton exchange polymer (e.g. Nafion) and the electrocatalyst is formed. Therefore, the GDE setup not only allows accurate potential control but also independent control over the reactant atmosphere, humidity and temperature. In addition, the identical location transmission electron microscopy (IL-TEM) technique can easily be adopted into the setup, enabling a combination of benchmarking with mechanistic studies.
Calibrating from Within: Multipoint Internal Calibration of a Quantitative Mass Spectrometric Assay of Serum Methotrexate
Authors: Hoffman Melissa A , Schmeling Michael , Dahlin Jayme L , Bevins Nicholas J , Cooper Donald P , Jarolim Petr , Fitzgerald Robert L , Hoofnagle Andrew N
Published: January 2020

Background

Clinical LC-MS/MS assays traditionally require that samples be run in batches with calibration curves in each batch. This approach is inefficient and presents a barrier to random access analysis. We developed an alternative approach called multipoint internal calibration (MPIC) that eliminated the need for batch-mode analysis.

Methods

The new approach used 4 variants of 13C-labeled methotrexate (0.026–10.3 µM) as an internal calibration curve within each sample. One site carried out a comprehensive validation, which included an evaluation of interferences and matrix effects, lower limit of quantification (LLOQ), and 20-day precision. Three sites evaluated assay precision and linearity. MPIC was also compared with traditional LC-MS/MS and an immunoassay.

Results

Recovery of spiked analyte was 93%–102%. The LLOQ was validated to be 0.017 µM. Total variability, determined in a 20-day experiment, was 11.5%CV. In a 5-day variability study performed at each site, total imprecision was 3.4 to 16.8%CV. Linearity was validated throughout the calibrator range (r2 > 0.995, slopes = 0.996–1.01). In comparing 40 samples run in each laboratory, the median interlaboratory imprecision was 6.55%CV. MPIC quantification was comparable to both traditional LC-MS/MS and immunoassay (r2 = 0.96–0.98, slopes = 1.04–1.06). Bland-Altman analysis of all comparisons showed biases rarely exceeding 20% when MTX concentrations were >0.4 µM.

Conclusion

The MPIC method for serum methotrexate quantification was validated in a multisite proof-of-concept study and represents a big step toward random-access LC-MS/MS analysis, which could change the paradigm of mass spectrometry in the clinical laboratory.
Tricuspid valve repair in children with hypoplastic left heart syndrome: impact of timing and mechanism on outcome
Authors: Ono Masamichi , Mayr Benedikt , Burri Melchior , Piber Nicole , Röhlig Christoph , Strbad Martina , Cleuziou Julie , Hager Alfred , Hörer Jürgen , Lange Rüdiger
Published: January 2020

OBJECTIVES

Our aim was to evaluate the results of tricuspid valve repair (TVr) in patients with hypoplastic left heart syndrome during staged reconstruction, focussing on the timing of the repair and the mechanisms of tricuspid regurgitation (TR).

METHODS

Records of 44 children with hypoplastic left heart syndrome who underwent a total of 62 tricuspid valve (TV) procedures during staged reconstruction were retrospectively analysed.

RESULTS

TVr was performed before stage II in 4 (9%) patients, at stage II in 23 (52%) patients, between stages II and III in 3 (7%) patients and at stage III in 14 (32%) patients. The median age at the first TV procedure was 5 months. At surgery, TR emanated commonly from the anteroseptal commissure in 21 (48%) patients. Anterior leaflet prolapse was observed most frequently (n = 23; 52%), followed by septal leaflet restriction (n = 22; 50%), dilated annulus (n = 21; 48%) and cleft anterior leaflet (n = 9; 21%). Surgical techniques included commissuroplasty in 27 (61.4%) patients, leaflet adaptation in 20 (44%) patients, partial annuloplasty in 11 (25%) patients, chordal reconstruction in 10 (23%) patients and cleft closure in 10 (23%) patients. Among all 44 patients, 27 (61%) patients had preoperative grade III TR and 17 (39%) patients had grade IV; postoperatively, there were no patients with grade IV, 25 patients with grade III (57%), 10 patients with grade II (23%) and 6 patients with grade I (14%). Fifteen patients required redo TV surgeries. Reoperation-free survival was 52% at 5 years. Lower weight at initial TVr predicted mortality [hazard ratio (HR) 0.7, P = 0.044] and reoperation (HR 0.8, P = 0.015). TVr before stage II was a risk for both reoperation (HR 5.5, P = 0.042) and TV replacement (HR 36.9, P = 0.013). Among morphological factors, septal leaflet restriction was a risk for reoperation (HR 4.7, P = 0.017) and anterior (HR 4.7, P = 0.037) and posterior (HR 7.3, P = 0.015) leaflet chordal anomaly for TV replacement.

CONCLUSIONS

Anterior leaflet prolapse and septal leaflet restriction are the main mechanisms of TR in hypoplastic left heart syndrome. Early-onset TR before stage II predicts worse outcome. Refinements to repair techniques in early infancy, especially for septal leaflet restrictions and chordal anomalies, are mandatory to improve outcomes.
Recent geomagnetic variations and the force balance in Earth’s core
Authors: Aubert Julien
Published: January 2020

The nature of the force balance that governs the geodynamo is debated. Recent theoretical analyses and numerical simulations support a quasigeotrophic (QG), magneto-Archimedes-Coriolis (MAC) balance in Earth’s core, where the Coriolis and pressure forces equilibrate at leading order in amplitude, and where the buoyancy, Lorentz and ageostrophic Coriolis forces equilibrate at the next order. In contrast, earlier theoretical expectations have favoured a magnetostrophic regime where the Lorentz force would reach leading order at the system scale. The dominant driver (buoyant or magnetic) for the general circulation in Earth’s core is equally debated. In this study, these questions are explored in the light of the high-quality geomagnetic data recently acquired by satellites and at magnetic ground observatories. The analysis involves inverse geodynamo modelling, a method that uses multivariate statistics extracted from a numerical geodynamo model to infer the state of Earth’s core from a geomagnetic field model interpretation of the main field and secular variation data. To test the QG-MAC dynamic hypothesis against the data, the framework is extended in order to explicitly prescribe this force balance into the inverse problem solved at the core surface. The resulting inverse solutions achieve a quantitatively adequate fit to the data while ensuring deviations from the QG-MAC balance (which amount to an inertial driving of the flow) lower than each of the leading forces. The general circulation imaged within the core over the past two decades confirms the existence of a planetary-scale, eccentric, axially columnar gyre that comprises an intense, equatorially symmetric jet at high latitudes in the Pacific hemisphere. The dominant driver of this circulation is shown to be of buoyant nature, through a thermal wind balance with a longitudinally hemispheric buoyancy anomaly distribution. Geomagnetic forecasts initiated with the inverted core states are systematically more accurate against the true interannual geomagnetic field evolution when enforcing the QG-MAC constraint. This force balance is therefore consistent with the geomagnetic data at the large scales of Earth’s core that can be imaged by the method.
Institutional Training Opportunities for PhD Students in Laboratory Medicine: An Unmet Career Development Need?
Authors: Colby Jennifer M , Wheeler Ferrin C , Petrie Kimberly A , Gould Kathleen L , Schmitz Jonathan E
Published: January 2020

In the United States, the credentialing of PhD-scientists as medical directors of clinical laboratories is driven by formal postdoctoral training programs. Prior to acceptance in one these accredited fellowships, however, a trainee’s exposure to the field can be far less standardized, with significant ramifications for their awareness and competitiveness. In the current article, we describe our recent experiences in developing local, institution-based immersion opportunities for PhD experiences in the subdisciplines of laboratory medicine (clinical microbiology, clinical chemistry, and molecular genetics/genomics). It is our hope that this article—and a corresponding online survey—can prompt reflection and discussion on the status of early career training opportunities in these key clinical areas.
Pillars not Principles: The Status of Humanity and Military Necessity in the Law of Armed Conflict
Authors: Winter Elliot
Published: January 2020

Humanity and military necessity are often said to be ‘principles’ of the law of armed conflict (LOAC). However, for Dworkin, a concept must satisfy certain criteria in order to earn the status of a principle. First, principles carry different weightings to each other so that one may triumph in the event of a clash. Secondly, principles are capable of superseding positive rules so that coherence in the regime over which they preside is maintained. This article contends that neither criterion is satisfied by humanity or military necessity. Consequently, it argues that these concepts are not truly principles and that, instead, they are better viewed as ‘pillars’ of the LOAC.
Racial Disparities in Cancer Presentation and Outcomes: The Contribution of Overdiagnosis
Authors: Marcadis Andrea R , Davies Louise , Marti Jennifer L , Morris Luc G T
Published: January 2020

Background

Racial disparities in cancer have been attributed to population differences in access to care. Differences in cancer overdiagnosis rates are another, less commonly considered cause of disparities. Here, we examine the contribution of overdiagnosis to observed racial disparities in papillary thyroid cancer and estrogen/progesterone receptor positive (ER/PR+) breast cancer.

Methods

We used Surveillance, Epidemiology, End-Results (SEER) 13 for analysis of white and black non-Hispanic persons with papillary thyroid cancer or ER/PR+ breast cancer (1992–2014). Analyses were performed using SeerStat (v8.3.5, March 2018). All statistical tests were two-sided.

Results

White persons had higher incidence of papillary thyroid cancer than black persons (14.3 vs 7.7 cases per 100 000 age-adjusted population) and ER/PR+ breast cancer (94.8 vs 70.9 cases per 100 000 age-adjusted population) (P < .001). In papillary thyroid cancer, the entire incidence difference was from more frequent diagnosis of 2-cm or less (10.0 vs 4.9 cases per 100 000 population) and localized or regional (13.8 vs 7.4 cases per 100 000 population) cancers in white persons (P < .001), without corresponding excess of metastatic disease, cancers greater than 4 cm, or incidence-based mortality in black persons. In women with ER/PR+ breast cancer, 95% of the incidence difference was from more 2-cm or less (61.2 vs 38.1 cases per 100 000 population) or 2.1- to 5-cm (25.4 vs 23.4 cases per 100 000 population), localized (65.1 vs 43.0 cases per 100 000 population) cancers diagnosed in white women (P < .001), with slightly higher incidence of tumors greater than 5 cm (10.1 vs 9.3 cases per 100 000 population, P < .001) and incidence-based mortality (8.1 vs 7.2 cases per 100 000 population, P < .001) among black women. Overall, 20–30 additional small or localized ER/PR+ breast cancers were diagnosed in white compared with black women for every large or advanced tumor avoided by early detection. Overdiagnosis was estimated 1.3–2.5 times (papillary thyroid cancer) and 1.7–5.7 times (ER/PR+ breast cancer) higher in white compared with black populations.

Conclusions

Differences in low-risk cancer identification among populations lead to overestimation of racial disparities. Estimates of overdiagnosed cases should be considered to improve care and eliminate disparities while minimizing harms of overdiagnosis.
Losing the Right to Stay: Revocation of Refugee Permits in Norway
Authors: Brekke Jan-Paul , Birkvad Simon Roland , Erdal Marta Bivand
Published: January 2020

Following the record number of asylum seekers to Europe in 2015, Norway intensified its practice of revoking migrants’ residence permits and citizenships, which primarily affected refugees and their families, and reflects a broader international trend of increased use of temporary protection. This article explores the effects of revocation on individuals, their families and wider communities by analysing how revocation is experienced and its consequences for integration processes. Drawing on the concepts of deregulariation, temporality and integration, our analysis builds on interviews with migrants from Somalia and Afghanistan living in Norway. We find severe consequences for individuals affected by revocation processes and discuss spillover effects, most notably what we refer to as disintegration. Our conclusions point to the need for futher analytical scrutiny of both the consequences of intensified revocation practices and their purported effectiveness as a measure to regulate immigration.
Intersphincteric epidermoid inclusion cyst: report of a rare case
Authors: Ashcroft James , Mahler-Araujo Betania , Davies Richard J
Published: January 2020

Epidermoid inclusion cysts of the perineal region are a rare entity, which require appropriate diagnosis and management. Here we describe the unusual case of a large protruding epidermoid inclusion cyst originating from the intersphincteric anal plane, which was mobilized and excised successfully. Essential investigations to ensure accurate diagnosis in addition to surgical technique to reduce recurrence and patient morbidity are described in this case report.
The unreasonable effectiveness of Nonstandard Analysis
Authors: Sanders Sam
Published: January 2020

As suggested by the title, the aim of this paper is to uncover the vast computational content of classical Nonstandard Analysis. To this end, we formulate a template ${\mathfrak{C}\mathfrak{I}}$ which converts a theorem of ‘pure’ Nonstandard Analysis, i.e. formulated solely with the nonstandard definitions (of continuity, integration, differentiability, convergence, compactness, etc.), into the associated effective theorem. The latter constitutes a theorem of computable mathematics no longer involving Nonstandard Analysis. To establish the huge scope of ${\mathfrak{C}\mathfrak{I}}$, we apply this template to representative theorems from the Big Five categories from Reverse Mathematics. The latter foundational program provides a classification of the majority of theorems from ‘ordinary’, i.e. non-set theoretical, mathematics into the aforementioned five categories. The Reverse Mathematics zoo gathers exceptions to this classification, and is studied in [ 74, 77] using ${\mathfrak{C}\mathfrak{I}}$. Hence, the template ${\mathfrak{C}\mathfrak{I}}$ is seen to apply to essentially all of ordinary mathematics, thanks to the Big Five classification (and associated zoo) from Reverse Mathematics. Finally, we establish that certain ‘highly constructive’ theorems, called Herbrandizations, also imply the original theorem of Nonstandard Analysis from which they were obtained via ${\mathfrak{C}\mathfrak{I}}$.
Lensing efficiency for gravitational wave mergers
Authors: Contigiani O
Published: January 2020

We gain insight into the effects of gravitational lensing on the estimated distribution of merging binaries observed through gravitational waves. We quantify the efficiency of magnification for gravitational wave events in the geometric optics limit, and we compare it to the electromagnetic case by making minimal assumptions about the distribution of intrinsic properties for the source population. We show that lensing effects leave a recognizable signature on the observed rates, and that they can be prominent only in the presence of an extremely steep mass function (or redshift evolution) and mainly at low inferred redshifts. We conclude that gravitational magnification does not represent a significant systematic for gravitational wave merger studies in the LIGO–Virgo era.
A discrete chemo-dynamical model of M87’s globular clusters: Kinematics extending to ∼400 kpc
Authors: Li Chao , Zhu Ling , Long R J , Mao Shude , Peng Eric W , Sarzi Marc , van de Ven Glenn , Zhang Hongxin , Guo Rui , Xue Xiangxiang , Longobardi Alessia , Côté Patrick , Ferrarese Laura , Liu Chengze , Gwyn Stephen , Lim Sungsoon , Ko Youkyung
Published: January 2020

We study the mass distribution and kinematics of the giant elliptical galaxy M87 (NGC 4486) using discrete chemo-dynamical, axisymmetric Jeans equation modelling. Our catalogue comprises 894 globular clusters (GCs) extending to a projected radius of ∼430 kpc with line-of-sight velocities and colours, and Multi Unit Spectroscopic Explorer integral field unit data within the central 2.4 kpc of the main galaxy. The gravitational potential for our models is a combination of a luminous matter potential with a varying mass-to-light ratio for the main galaxy, a supermassive black hole and a dark matter (DM) potential with a cusped or cored DM halo. The best-fitting models with either a cusped or a cored DM halo show no significant differences and both are acceptable. We obtain a total mass of $(2.16 \pm 0.38) \times 10^{13} \, \mathrm{M}_{\odot }$ within ∼400 kpc. By including the stellar mass-to-light ratio gradient, the DM fraction increases from ∼26 per cent (with no gradient) to ∼73 per cent within $1\, R_e^{\rm maj}$ (major axis of half-light isophote, 14.2 kpc), and from ∼84 per cent to ∼94 per cent within $5\, R_e^{\rm maj}$ (71.2 kpc). Red GCs have moderate rotation with Vmax/σ ∼ 0.4, and blue GCs have weak rotation with Vmax/σ ∼ 0.1. Red GCs have tangential velocity dispersion anisotropy, while blue GCs are consistent with being nearly isotropic. Our results suggest that red GCs are more likely to be born in situ, while blue GCs are more likely to be accreted.