bluuebunny/crossref_metadata_2025 huggingface dataset:
Whey protein isolate/gum arabic intramolecular soluble complexes improving the physical and oxidative stabilities of conjugated linoleic acid emulsions
Authors: Yao Xiaolin , Xiang Shengping , Nie Ke , Gao Zhiming , Zhang Weiqi , Fang Yapeng , Nishinari Katsuyoshi , Phillips Glyn O. , Jiang Fatang
Published: January 2016

Protein–polysaccharide intramolecular soluble complexes are proved to have superior emulsifying properties in stabilizing PUFAs-based emulsions.
Controlled synthesis of highly dispersed and nano-sized Ru catalysts supported on carbonaceous materials via supercritical fluid deposition
Authors: Zhang Yimin , Jiang Haoxi , Li Guiming , Zhang Minhua
Published: January 2016

Highly dispersed Ru nanoparticles supported on carbonaceous materials were fabricated by supercritical fluid deposition technology and characterized by high-resolution transmission electron microscopy, and X-ray photoelectron spectroscopy.
The logical and psychological structure of physical chemistry and its relevance to graduate students' opinions about the difficulties of the major areas of the subject
Authors: Tsaparlis Georgios
Published: January 2016

In a previous publication, Jensen's scheme for the logical structure of chemistry was employed to identify a logical structure for physical chemistry, which was further used as a tool for analyzing the organization of twenty physical chemistry textbooks. In addition, science education research was considered for the study of the psychological structure of physical chemistry. In this companion paper, the findings are presented of a semi-structured interview study with seventeen chemistry graduates, which aimed to find out their opinion about the difficulties of the various areas of physical chemistry, their disposition towards the subject, and their explanations for the difficulties identified, and in this way to study further the psychological structure of physical chemistry. A mixture of an intensive inductive and a confirmatory data analysis was carried out that revealed ideas and trends and allowed for a reliable portrait of learners to emerge by identifying similarities and differences in the data. Students unanimously found the phenomenological subjects (classical thermodynamics, electrochemistry, chemical kinetics) easier than the submicroscopic subjects of quantum chemistry and statistical thermodynamics. The reasons invoked included that the latter subjects deal with more difficult and abstract concepts, and also their highly mathematical nature. Many students found classical thermodynamics simpler than quantum chemistry, because it “has logic”, includes “tangible examples”, and they had encountered related topics before (especially in high school). The findings for electrochemistry and chemical kinetics were more or less similar to those for classical thermodynamics. Implications, generalizability, and limitations of the findings and prospects for further research are discussed.
Glutathione boosting the cytotoxicity of a magnetic platinum(iv) nano-prodrug in tumor cells
Authors: Zhu Zhenzhu , Wang Zenghui , Hao Yigang , Zhu Chengcheng , Jiao Yang , Chen Huachao , Wang Yun-Ming , Yan Jun , Guo Zijian , Wang Xiaoyong
Published: January 2016

Fe3O4 nanoparticles with Pt-prodrug payloads display MRI capability and tumor-specific cytotoxicity correlating positively with glutathione-mediated DNA cleavage and reduction.
Microphase separation of short wormlike diblock copolymers with a finite interaction range
Authors: Jiang Ying , Zhang Xinghua , Miao Bing , Yan Dadong , Chen Jeff Z. Y.
Published: January 2016

A study on the structural properties of low-molecular weight AB diblock copolymers indicates substantial deviations from the properties of high-molecular weight polymers.
Novel peapod NiO nanoparticles encapsulated in carbon fibers for high-efficiency supercapacitors and lithium-ion batteries
Authors: Feng Yangyang , Zhang Huijuan , Zhang Yan , Bai Yuanjuan , Wang Yu
Published: January 2016

We report novel peapod NiO nanoparticles encapsulated in carbon fibers, which exhibit outstanding electrochemical performances in both SCs and LIBs.
Sr2LaAlTiO7: a new Ruddlesden–Popper compound with excellent microwave dielectric properties
Authors: Liu Bing , Liu Xiao Qiang , Chen Xiang Ming
Published: January 2016

A newn= 2 type Ruddlesden–Popper compound Sr2LaAlTiO7was synthesized and characterized, and the microwave dielectric properties were investigated together with their microstructures.
Fluoride-assisted synthesis of bimodal microporous SSZ-13 zeolite
Authors: Zhu Xiaochun , Kosinov Nikolay , Hofmann Jan P. , Mezari Brahim , Qian Qingyun , Rohling Roderigh , Weckhuysen Bert M. , Ruiz-Martínez Javier , Hensen Emiel J. M.
Published: January 2016

The presence of small amount of fluoride in alkaline hydrothermal synthesis of SSZ-13 zeolite yields bimodal microporous particles with substantially improved performance in the methanol-to-olefins (MTO) reaction.
Fluorine-directed 1,2-trans glycosylation of rare sugars
Authors: Aiguabella Nuria , Holland Mareike C. , Gilmour Ryan
Published: January 2016

To reconcile the urgent need to access well defined β-configured 2,6-di-deoxypyranose analogues for chemical biology, with the intrinsic α-selectivity of the native system, the directing role of fluorine at C2 has been explored.
Dual surface sliding mode controller for photovoltaic systems enhanced by a ripple domain search maximum power point tracking algorithm for fast changing environmental conditions
Authors: Ghaffarzadeh Navid , Bijani Sepehr
Published: January 2016

In this research, a dual surface sliding mode controller is proposed and implemented to increase robustness and speed of boost converter, its asymptotic response is proved in the presence of disturbances. In addition, a filtered mapping pulse width modulation technique is developed to attenuate the chattering problem caused by finite frequency switching. Ripple domain search (RDS), a precise maximum power point tracking (MPPT) algorithm, is suggested to find the maximum power point (MPP) in photovoltaics. RDS uses the inherent ripple problem of the converter as a tool for finding MPP. By combining the proposed fast controller and the RDS algorithm, a fast and robust MPPT technique is obtained, which is simple to implement, eliminates the need for initial parameter tuning and is free from oscillations. Moreover, the proposed controlling method and MPPT algorithm are tested using Mitsubishi Electric MF170W module and their efficiency is compared with conventional methods (including P & O) in fast irradiation changing conditions. The proposed method harvests a 6% higher power than P & O and constant voltage. Compared with incremental conductance 24% more power is harvested. Finally, the practicality of the controller and algorithm was experimentally validated with a prototype system using a 5 W Evergreen module.
Electrostatic levitation facility optimized for neutron diffraction studies of high temperature liquids at a spallation neutron source
Authors: Mauro N. A. , Vogt A. J. , Derendorf K. S. , Johnson M. L. , Rustan G. E. , Quirinale D. G. , Kreyssig A. , Lokshin K. A. , Neuefeind J. C. , An Ke , Wang Xun-Li , Goldman A. I. , Egami T. , Kelton K. F.
Published: January 2016

Neutron diffraction studies of metallic liquids provide valuable information about inherent topological and chemical ordering on multiple length scales as well as insight into dynamical processes at the level of a few atoms. However, there exist very few facilities in the world that allow such studies to be made of reactive metallic liquids in a containerless environment, and these are designed for use at reactor-based neutron sources. We present an electrostatic levitation facility, NESL (for Neutron ElectroStatic Levitator), which takes advantage of the enhanced capabilities and increased neutron flux available at spallation neutron sources (SNSs). NESL enables high quality elastic and inelastic neutron scattering experiments to be made of reactive metallic and other liquids in the equilibrium and supercooled temperature regime. The apparatus is comprised of a high vacuum chamber, external and internal neutron collimation optics, and a sample exchange mechanism that allows up to 30 samples to be processed between chamber openings. Two heating lasers allow excellent sample temperature homogeneity, even for samples approaching 500 mg, and an automated temperature control system allows isothermal measurements to be conducted for times approaching 2 h in the liquid state, with variations in the average sample temperature of less than 0.5%. To demonstrate the capabilities of the facility for elastic scattering studies of liquids, a high quality total structure factor for Zr64Ni36 measured slightly above the liquidus temperature is presented from experiments conducted on the nanoscale-ordered materials diffractometer (NOMAD) beam line at the SNS after only 30 min of acquisition time for a small sample (∼100 mg).
An extended fractal growth regime in the diffusion limited aggregation including edge diffusion
Authors: Ghosh Aritra , Batabyal R. , Das G. P. , Dev B. N.
Published: January 2016

We have investigated on-lattice diffusion limited aggregation (DLA) involving edge diffusion and compared the results with the standard DLA model. For both cases, we observe the existence of a crossover from the fractal to the compact regime as a function of sticking coefficient. However, our modified DLA model including edge diffusion shows an extended fractal growth regime like an earlier theoretical result using realistic growth models and physical parameters [Zhang et al., Phys. Rev. Lett. 73 (1994) 1829]. While the results of Zhang et al. showed the existence of the extended fractal growth regime only on triangular but not on square lattices, we find its existence on the square lattice. There is experimental evidence of this growth regime on a square lattice. The standard DLA model cannot characterize fractal morphology as the fractal dimension (Hausdorff dimension, DH) is insensitive to morphology. It also predicts DH = DP (the perimeter dimension). For the usual fractal structures, observed in growth experiments on surfaces, the perimeter dimension can differ significantly (DH ≠ DP) depending on the morphology. Our modified DLA model shows minor sensitivity to this difference.
Locally weighted histogram analysis and stochastic solution for large-scale multi-state free energy estimation
Authors: Tan Zhiqiang , Xia Junchao , Zhang Bin W. , Levy Ronald M.
Published: January 2016

The weighted histogram analysis method (WHAM) including its binless extension has been developed independently in several different contexts, and widely used in chemistry, physics, and statistics, for computing free energies and expectations from multiple ensembles. However, this method, while statistically efficient, is computationally costly or even infeasible when a large number, hundreds or more, of distributions are studied. We develop a locally WHAM (local WHAM) from the perspective of simulations of simulations (SOS), using generalized serial tempering (GST) to resample simulated data from multiple ensembles. The local WHAM equations based on one jump attempt per GST cycle can be solved by optimization algorithms orders of magnitude faster than standard implementations of global WHAM, but yield similarly accurate estimates of free energies to global WHAM estimates. Moreover, we propose an adaptive SOS procedure for solving local WHAM equations stochastically when multiple jump attempts are performed per GST cycle. Such a stochastic procedure can lead to more accurate estimates of equilibrium distributions than local WHAM with one jump attempt per cycle. The proposed methods are broadly applicable when the original data to be “WHAMMED” are obtained properly by any sampling algorithm including serial tempering and parallel tempering (replica exchange). To illustrate the methods, we estimated absolute binding free energies and binding energy distributions using the binding energy distribution analysis method from one and two dimensional replica exchange molecular dynamics simulations for the beta-cyclodextrin-heptanoate host-guest system. In addition to the computational advantage of handling large datasets, our two dimensional WHAM analysis also demonstrates that accurate results similar to those from well-converged data can be obtained from simulations for which sampling is limited and not fully equilibrated.
Effects of Lewis number on vorticity and enstrophy transport in turbulent premixed flames
Authors: Chakraborty Nilanjan , Konstantinou Ilias , Lipatnikov Andrei
Published: January 2016

The effects of Lewis number Le on both vorticity and enstrophy transport within the flame brush have been analysed using direct numerical simulation data of freely propagating statistically planar turbulent premixed flames, representing the thin reaction zone regime of premixed turbulent combustion. In the simulations, Le was ranged from 0.34 to 1.2 by keeping the laminar flame speed, thermal thickness, Damköhler, Karlovitz, and Reynolds numbers unchanged. The enstrophy has been shown to decay significantly from the unburned to the burned gas side of the flame brush in the Le ≈ 1.0 flames. However, a considerable amount of enstrophy generation within the flame brush has been observed for the Le = 0.34 case and a similar qualitative behaviour has been observed in a much smaller extent for the Le = 0.6 case. The vorticity components have been shown to exhibit anisotropic behaviour within the flame brush, and the extent of anisotropy increases with decreasing Le. The baroclinic torque term has been shown to be principally responsible for this anisotropic behaviour. The vortex stretching and viscous dissipation terms have been found to be the leading order contributors to the enstrophy transport for all cases, but the baroclinic torque and the sink term due to dilatation play increasingly important role for flames with decreasing Le. Furthermore, the correlation between the fluctuations of enstrophy and dilatation rate has been shown to play an important role in determining the material derivative of enstrophy based on the mean flow in the case of a low Le.
A step-wise steerable source of illumination for low-noise “Violin-Mode” shadow sensors, intended for use in interferometric gravitational wave detectors
Authors: Lockerbie N. A. , Tokmakov K. V.
Published: January 2016

A steerable low-noise source of illumination is described for shadow-sensors having a displacement sensitivity of ∼100 pm (rms)/√Hz, at 500 Hz, over a measuring span of at least ±0.5 mm. These sensors were designed to detect lateral “Violin-Mode” resonances in the highly tensioned fused-silica suspension fibres of the test-masses/mirrors for the Advanced Laser Interferometer Gravitational Wave Observatory gravitational wave detectors. The shadow sensors—one intended for each of the four fibres in a suspension—comprised a source of Near InfraRed (NIR) radiation (emitter) and a differential shadow-displacement sensor (detector), these bracketing the fibre under test. The suspension fibres themselves were approximately 600 mm long by 0.4 mm in diameter, and when illuminated from the side, they cast narrow, vertical, shadows onto their respective detectors—these being located at an effective distance of 50 fibre diameters behind the axes of the fibres themselves. The emitter described here was designed to compensate for a significant degree of mechanical drift or creep over time in the mean position of its suspension fibre. This was achieved by employing five adjacent columns of 8  × miniature NIR LEDs (Light Emitting Diodes, λ = 890 nm), with one column being activated at a time. When used in conjunction with a “reverse Galilean” telescope, the LED sources allowed the collimated beam from the emitter to be steered azimuthally in fine angular increments (0.65°), causing the fibre’s shadow to move laterally, in a step-wise manner, across the plane of its facing detector. Each step in shadow position was approximately 0.23 mm in size, and this allowed the fibre’s shadow to be re-centred, so as to bridge once again both elements of its photodiode detector—even if the fibre was off-centred by as much as ±0.5 mm. Re-centring allowed Violin-Mode vibrations of the fibre to be sensed once again as differential AC photocurrents, these flowing in anti-phase in the two elements of the “split-photodiode” detector.
A generic “micro-Stoney” method for the measurement of internal stress and elastic modulus of ultrathin films
Authors: Favache Audrey , Ryelandt Sophie , Melchior Maxime , Zeb Gul , Carbonnelle Pierre , Raskin Jean-Pierre , Pardoen Thomas
Published: January 2016

Accurate measurement of the mechanical properties of ultra-thin films with thicknesses typically below 100 nm is a challenging issue with an interest in many fields involving coating technologies, microelectronics, and MEMS. A bilayer curvature based method is developed for the simultaneous determination of the elastic mismatch strain and Young’s modulus of ultra-thin films. The idea is to deposit the film or coating on very thin cantilevers in order to amplify the curvature compared to a traditional “Stoney” wafer curvature test, hence the terminology “micro-Stoney.” The data reduction is based on the comparison of the curvatures obtained for different supporting layer thicknesses. The elastic mismatch strain and Young’s modulus are obtained from curvature measurements of cantilevers before and after the film deposition. The data reduction scheme relies on both analytical and finite element calculations, depending on the magnitude of the curvature. The experimental validation has been performed on ultra-thin low pressure chemical vapor deposited silicon nitride films with thickness ranging between 54 and 133 nm deposited on silicon cantilevers. The technique is sensitive to the cantilever geometry, in particular, to the thickness ratio and width/thickness ratio. Therefore, the precision in the determination of the latter quantities determines the accuracy on the extracted elastic mismatch strain and elastic modulus. The method can be potentially applied to films as thin as a few nanometers.
Polarization-resolved hyperspectral stimulated Raman scattering microscopy for label-free biomolecular imaging of the tooth
Authors: Wang Zi , Zheng Wei , Hsu Chin-Ying Stephen , Huang Zhiwei
Published: January 2016

We report the development and implementation of a rapid polarization-resolved hyperspectral stimulated Raman scattering (SRS) microscopy technique for label-free biomolecular imaging of the tooth. The hyperspectral SRS imaging technique developed covers both fingerprint (800–1800 cm−1) and high-wavenumber (2800–3600 cm−1) regions for tooth Raman imaging without fluorescence background interference with an imaging speed of <0.3 s per frame of 512 × 512 pixels (∼1 μs per pixel), that is, >106 faster than confocal Raman imaging. Significant differences of hyperspectral SRS spectra among different tooth locations (e.g., dentin, enamel, and dentin-enamel junction) are observed, revealing the biochemical distribution differences across the tooth. Further polarization-resolved SRS imaging shows different polarization dependences related to the molecular orientation differences of various tooth locations. This work demonstrates the potential of polarization-resolved hyperspectral SRS imaging technique developed in rapidly characterizing biochemical structures and compositions as well as biomolecule organizations/orientations of the tooth without labeling.
Fine asymptotic behavior for eigenvalues of random normal matrices: Ellipse case
Authors: Lee Seung-Yeop , Riser Roman
Published: January 2016

We consider the random normal matrices with quadratic external potentials where the associated orthogonal polynomials are Hermite polynomials and the limiting support (called droplet) of the eigenvalues is an ellipse. We calculate the density of the eigenvalues near the boundary of the droplet up to the second subleading corrections and express the subleading corrections in terms of the curvature of the droplet boundary. From this result, we additionally get the expected number of eigenvalues outside the droplet. We also show that a certain Cauchy transform of the orthogonal polynomial vanishes in the bulk of the droplet up to an exponentially small error.
Sand waves in environmental flows: Insights gained by coupling large-eddy simulation with morphodynamics
Authors: Sotiropoulos Fotis , Khosronejad Ali
Published: January 2016

Sand waves arise in subaqueous and Aeolian environments as the result of the complex interaction between turbulent flows and mobile sand beds. They occur across a wide range of spatial scales, evolve at temporal scales much slower than the integral scale of the transporting turbulent flow, dominate river morphodynamics, undermine streambank stability and infrastructure during flooding, and sculpt terrestrial and extraterrestrial landscapes. In this paper, we present the vision for our work over the last ten years, which has sought to develop computational tools capable of simulating the coupled interactions of sand waves with turbulence across the broad range of relevant scales: from small-scale ripples in laboratory flumes to mega-dunes in large rivers. We review the computational advances that have enabled us to simulate the genesis and long-term evolution of arbitrarily large and complex sand dunes in turbulent flows using large-eddy simulation and summarize numerous novel physical insights derived from our simulations. Our findings explain the role of turbulent sweeps in the near-bed region as the primary mechanism for destabilizing the sand bed, show that the seeds of the emergent structure in dune fields lie in the heterogeneity of the turbulence and bed shear stress fluctuations over the initially flatbed, and elucidate how large dunes at equilibrium give rise to energetic coherent structures and modify the spectra of turbulence. We also discuss future challenges and our vision for advancing a data-driven simulation-based engineering science approach for site-specific simulations of river flooding.
Constant-time 2D and 3D through-bond correlation NMR spectroscopy of solids under 60 kHz MAS
Authors: Zhang Rongchun , Ramamoorthy Ayyalusamy
Published: January 2016

Establishing connectivity and proximity of nuclei is an important step in elucidating the structure and dynamics of molecules in solids using magic angle spinning (MAS) NMR spectroscopy. Although recent studies have successfully demonstrated the feasibility of proton-detected multidimensional solid-state NMR experiments under ultrafast-MAS frequencies and obtaining high-resolution spectral lines of protons, assignment of proton resonances is a major challenge. In this study, we first re-visit and demonstrate the feasibility of 2D constant-time uniform-sign cross-peak correlation (CTUC-COSY) NMR experiment on rigid solids under ultrafast-MAS conditions, where the sensitivity of the experiment is enhanced by the reduced spin-spin relaxation rate and the use of low radio-frequency power for heteronuclear decoupling during the evolution intervals of the pulse sequence. In addition, we experimentally demonstrate the performance of a proton-detected pulse sequence to obtain a 3D 1H/13C/1H chemical shift correlation spectrum by incorporating an additional cross-polarization period in the CTUC-COSY pulse sequence to enable proton chemical shift evolution and proton detection in the incrementable t1 and t3 periods, respectively. In addition to through-space and through-bond 13C/1H and 13C/13C chemical shift correlations, the 3D 1H/13C/1H experiment also provides a COSY-type 1H/1H chemical shift correlation spectrum, where only the chemical shifts of those protons, which are bonded to two neighboring carbons, are correlated. By extracting 2D F1/F3 slices (1H/1H chemical shift correlation spectrum) at different 13C chemical shift frequencies from the 3D 1H/13C/1H spectrum, resonances of proton atoms located close to a specific carbon atom can be identified. Overall, the through-bond and through-space homonuclear/heteronuclear proximities determined from the 3D 1H/13C/1H experiment would be useful to study the structure and dynamics of a variety of chemical and biological solids.
Intrinsic magnetism of monolayer graphene oxide quantum dots
Authors: Sun Yuanyuan , Zheng Yongping , Chen Jie , Zhang Weili , Tang Nujiang , Du Youwei
Published: January 2016

Monolayer graphene oxide quantum dots (GOQDs) were obtained by oxidative cutting. The magnetic properties of GOQDs were studied. The results show that most of GOQDs are nonmagnetic, and only few of GOQDs are weakly paramagnetic. The ratio of magnetic GOQDs with the average diameter of 4.13, 3.3, and 1.67 nm is 1/14, 1/15, and 1/70, respectively. It is proposed that the edge states magnetism is suppressed by the edge defects and/or the magnetic correlation induced spins cancellation between magnetic fragments of the boundary, and hydroxyl groups on the basal plane are the major magnetic source of magnetic GOQDs.
A top-gate GaN nanowire metal–semiconductor field effect transistor with improved channel electrostatic control
Authors: Gačević Ž. , López-Romero D. , Juan Mangas T. , Calleja E.
Published: January 2016

A uniformly n-type doped GaN:Si nanowire (NW), with a diameter of d = 90 nm and a length of 1.2 μm, is processed into a metal-semiconductor field effect transistor (MESFET) with a semi-cylindrical top Ti/Au Schottky gate. The FET is in a normally-ON mode, with the threshold at −0.7 V and transconductance of gm ∼ 2 μS (the transconductance normalized with NW diameter gm/d > 22 mS/mm). It enters the saturation mode at VDS ∼ 4.5 V, with the maximum measured drain current IDS = 5.0 μA and the current density exceeding JDS > 78 kA/cm2.
Impact of parylene-C thickness on performance of KTaO3 field-effect transistors with high-k oxide/parylene-C hybrid gate dielectric
Authors: Wei Tingting , Fujiwara Kohei , Kanki Teruo , Tanaka Hidekazu
Published: January 2016

The proposal of a hybrid gate dielectric systematically modulated with low-k material layer has been shown to be a promising strategy in the development of low-consumption field-effect transistors (FETs) with high performance. In this work, by fabricating KTaO3 FETs containing Y-doped Ta2O5/parylene-C hybrid gate dielectrics with different ratios of component thicknesses, we explored the dependence of the transistor electrical properties on the parylene-C layer thickness. Based on the results and analysis, an optimized transistor performance was achieved with an appropriate Y-doped Ta2O5/parylene-C thickness ratio from the point of view on low voltage operation. This study contributes to provide guidance for future device design and applications.
Stokes shift in semi-polar (112¯2) InGaN/GaN multiple quantum wells
Authors: Zhang Y. , Smith R. M. , Hou Y. , Xu B. , Gong Y. , Bai J. , Wang T.
Published: January 2016

The mechanism for the large Stokes Shifts of InGaN/GaN structures is under debate. Here, we report a systematic study on the Stokes shift of semi-polar (112¯2) InGaN/GaN multiple quantum wells (MQWs) with a wide spectral range from green (490 nm) to yellow (590 nm) by means of both photoluminescence excitation and time resolved PL measurements in comparison with their c-plane counterparts. The semi-polar samples exhibit a lower Stokes shift than their c-plane counterparts, although they show stronger localization effect than their c-plane counterparts. In the long wavelength region, the Stokes shift of the semi-polar MQWs shows a linear relationship with emission energy, but with a smaller gradient compared with their c-plane counterparts. The time-resolved PL measurements confirm a significant reduction in piezoelectric field of the semi-polar samples compared with the c-plane counterparts. It is suggested that the piezoelectric field induced polarization is the major mechanism for causing the large Stokes shift. The presented results contribute to better understanding of the long standing issue on the mechanism for the large Stokes shift.
Acoustically induced current in graphene by aluminum nitride transducers
Authors: Chen Yan , Zhang Hongxiang , Zhang Hao , Feng Zhihong , Zhao Hongyuan , Sun Chongling , Zheng Shijun , Pang Wei , Zhang Daihua
Published: January 2016

We report on the excitation of acousto-eletric (AE) charge transport in monolayer graphene by acoustic transducers based on aluminum nitride thin films. The acoustic waves induced macroscopic current flow that linearly scaled with input power. The AE current exhibited unique frequency dependence due to special configuration and piezoelectric properties of the transducer, which led to transitions between traveling and standing acoustic waves across a characteristic frequency. A Finite Element model was built to investigate and understand the phenomena and the underlying mechanisms.
Solid-state conversion of (94-x)(Na1/2Bi1/2)TiO3-6BaTiO3-x(K1/2Na1/2)NbO3 single crystals and their enhanced converse piezoelectric properties
Authors: Park Ji-Hoon , Kang Suk-Joong L.
Published: January 2016

(94-x)(Na1/2Bi1/2)TiO3-6BaTiO3-x(K1/2Na1/2)NbO3 (NBT-6BT-xKNN) piezoelectric ceramics have notable potential for replacing lead containing piezoelectric ceramics in actuator applications due to their exceptionally large strain. However, a high electric field for producing a large strain and a large hysteresis are critical issues that should be resolved for practical actuator applications. In an attempt to address these issues and optimize the piezoelectric performance, we fabricated NBT-6BT-xKNN (x = 0 - 5) piezoelectric single crystals with a size of 8 x 8x 10 mm by the solid-state single crystal growth method and systematically measured their electrical properties. With increased addition of KNN to replace NBT, the ferroelectricity and piezoelectricity of the fabricated [001] NBT-6BT-xKNN single crystals decreased, but their unipolar strain and hysteresis were considerably improved. For NBT-6BT-5KNN single crystals, the largest maximum strain (Smax) was 0.57% at 6 kV/mm, showing a converse piezoelectric constant (Smax/Emax) of 950 pm/V, and their hysteresis in the unipolar S-E curve was 12% at 6kV/mm, which would be appropriate for some actuator applications. Our results demonstrate the applicability of the produced single crystals as lead-free piezoelectric actuator components.
Elemental intermixing within an ultrathin SrRuO3 electrode layer in epitaxial heterostructure BaTiO3/SrRuO3/SrTiO3
Authors: Zhang H. B. , Qi R. J. , Ding N. F. , Huang R. , Sun L. , Duan C. G. , Fisher Craig A. J. , Chu J. H. , Ikuhara Y.
Published: January 2016

Aberration corrected scanning transmission electron microscopy is used to directly observe atom columns in an epitaxial BaTiO3 thin film deposited on a 3.6 nm-thick SrRuO3 electrode layer above an SrTiO3 (001) substrate. Compositional gradients across the heterointerfaces were examined using electron energy-loss spectroscopy techniques. It was found that a small amount of Ba and Ti had diffused into the SrRuO3 layer, and that this layer contained a non-negligible concentration of oxygen vacancies. Such point defects are expected to degrade the electrode’s electronic conductivity drastically, resulting in a much longer screening length. This may explain the discrepancy between experimental measurements and theoretical estimates of the ferroelectric critical thickness of a BaTiO3 ferroelectric barrier sandwiched between metallic SrRuO3 electrodes, since theoretical calculations generally assume ideal (stoichiometric) perovskite SrRuO3.
Identification of the Cat Attractants Isodihydronepetalactone and Isoiridomyrmecin from Acalypha indica
Authors: Scaffidi Adrian , Algar Dave , Bohman Björn , Ghisalberti Emilio L. , Flematti Gavin
Published: January 2016

Acalypha indica is a herb that grows throughout the tropical regions of the world. As well as being exploited for medicinal use, the roots of this plant are known to elicit a drug-like effect in cats. Recent research into feral cat control on Christmas Island has investigated whether a preparation of the roots of A. indica might be effective in traps to attract feral cats. However, the volatile nature of the attractants made it unviable for use in traps for more than a few days. In this study, we investigated the volatile components emitted by the plant roots and identified two iridoid compounds, (4R,4aR,7S,7aR)-isodihydronepetalactone and (4R,4aS,7S,7aR)-isoiridomyrmecin, which are known to affect behavioural activity in cats. Synthesis of standards confirmed the stereochemistry of both compounds emitted by the plant. Potential application of these compounds in feral cat control is discussed.
Soil-specific calibration of capacitance sensors considering clay content and bulk density
Authors: Parvin Nargish , Degré Aurore
Published: January 2016

Soil hydrology research requires the accurate measurement of soil water content. Recently, less expensive capacitance sensors (CS) have become popular for the measurement of soil moisture across soil profiles, but these sensors need to be calibrated for precise results. The purpose of the present study was to determine the effect of clay content and bulk density (ρb) on the calibration of CS. Two different CS (10HS and 5TM) were considered for the study. Clay content and ρb of the soils were determined from two different sites and from three different depths (0–5, 25–30 and 50–60 cm) of an experimental field in Gembloux, Belgium. Custom calibration (CC) equations were developed using packed soil columns following the same ρb at sequential volumetric water content (θ) levels. The factory-supplied calibration (FSC) showed an overestimation of θ (0.04–0.07 m3 m–3) with the 10HS sensor, and an underestimation of θ (0.06–0.077 m3 m–3) with the 5TM sensor for the entire calibration range. The variance in raw sensor outputs for different ρb and clay content of soil depths was not highly significant because the soil had limited range of variability in ρb and clay content. However, the CC is recommended in parallel with FSC for the precise measurement of soil moisture with CS.
Microstructural evolution and deformation behaviour of wrought Mg–Al–Zn alloys under dynamic compression
Authors: Lu L. , Zhao J. , Liu L. , Wang Z.
Published: January 2016

We perform dynamic compression to extruded AZ31 Mg alloys both along and perpendicular to the extrusion direction (ED) at a high strain rate of 1400 s−1 using split Hopkison pressure bar, and study the microstructure, texture evolution and mechanical anisotropy. We find that the temperature and loading direction play an important role in affecting microstructure evolution and flow stress. The mechanical anisotropy, yield strength and hardening ability are found to decrease with the rise of temperature. Moreover, the grains are also found to be refined remarkably, and the strong basal texture is weakened substantially owing to the dynamic recrystallisation especially in the case where dynamic compression is carried out perpendicular to the ED at 473 K.
Effect of travel speed on the microstructure of Al-to-Mg FSW joints
Authors: Zhao Y. , Huang L. , Zhao Z. , Yan K.
Published: January 2016

The effect of relatively high travel speed on the microstructure (SEM) and mechanical properties of friction stir welded dissimilar 5754 Al/AZ31Mg alloys has been characterised. With the Al alloy placed on the advancing side, travel speed were varied from 100 to 350 mm min−1 and the mechanical properties of the joint subsequently determined by tensile tests on cross-section samples. The best (but moderate) properties were obtained at 200 mm min−1. The joint failed by brittle fracture along localised bands on the severely deformed Al side containing Al3Mg2. The lowest travel speed developed a eutectic Al12Mg17 microstructure. The joint obtained at 100 and 250 mm min−1 failed, by ductile and brittle mixed fracture modes, at the bonding interface containing continuous intermetallic compounds.
Microstructure and mechanical properties of AZ31 alloy ring processed by hot forging
Authors: Zhang J. , Huang H.
Published: January 2016

AZ31 alloy ring was successfully processed by hot forging. The effects of effective strain and temperature distributions on the microstructure and the relationship between microstructure and mechanical properties of the ring were investigated. The effective strain distribution at the centre region is relatively uniform, while the temperature in or near the flash region is higher than the other regions. A refined but inhomogeneous microstructure is obtained in the ring. It shows that the larger the accumulated strain and the lower the temperature are, the finer and more homogeneous the microstructure will be achieved. The mechanical responses of the ring from different tensile directions differ greatly. The radial direction sample shows the lowest yield strength and the largest fracture elongation.
Critical assessment 19: Stacking fault energies of austenitic steels
Authors: Lee Y.-K. , Lee S.-J. , Han J.
Published: January 2016

The stacking fault energy (SFE) can play a key role in the deformation mechanism (e.g. transformation-induced plasticity and twinning-induced plasticity) of austenitic steels. Therefore, tremendous efforts have been devoted to exploring the evaluation methods and controlling parameters (e.g. alloying elements and temperature) that determine the SFE and its relationship to mechanical twinning. We provide here a summary of recent progress in studies of the SFE of austenite and of unsolved issues that may stimulate further investigation.
On the microstructure and erosion–corrosion resistance of AlCrFeCoNiCu high-entropy alloy via annealing treatment
Authors: Zhao J. H. , Ji X. L. , Shan Y. P. , Fu Y. , Yao Z.
Published: January 2016

As-cast AlCrFeCoNiCu high-entropy alloy (HEA) was a solid solution of body-centered cubic (BCC) and face-centered cubic phases with a typical dendrite and interdendrite structures. The precipitated intermediate phases in 600°C annealed HEA are responsible for the improved hardness. After 1000°C annealing treatment, the crystalline was re-arranged because of the decomposition of BCC phases. The 1000°C annealed HEA has the best corrosion resistance due to its re-arranged crystalline structure. Meanwhile, the 600°C annealed HEA has the best erosion–corrosion resistance for its highest hardness and its wear rate is more than two times lower than that of AISI 304 stainless steel. Therefore, the HEA has a potential application in saline–sand slurry because of its superior corrosion and erosion–corrosion resistance.
Microstructure, thermodynamics and compressive properties of AlCrCuNiZrx (x = 0,1) high-entropy alloys
Authors: Wang Xiao-Rong , Wang Zhao-Qin , Lin Tie-Song , He Peng
Published: January 2016

Two high-entropy alloys (HEAs), AlCrCuNiZr x ( x = 0,1), were prepared by arc melting. The AlCrCuNi alloy consists of a face centered cubic (FCC) phase, a body centered cubic (BCC) phase and an eutectic phase, while the AlCrCuNiZr alloy contains a FCC phase, a BCC phase and an intermetallic phase. The traditional thermodynamic parameters of HEAs were converted into thermodynamic-parameter-functions of composition variable x, including Δ Gmix( x), Δ Hmix( x), Δ Smix( x), Ω( x), δ( x),Δχ( x) and VEC( x). The thermodynamic-parameter-curves could be obtained through thermodynamic-parameter-functions via Matlab. The thermodynamics of the two alloys were analysed using the thermodynamic-parameter-curves of the AlCrCuNiZr x ( x∈[0 1]) alloys. The addition of Zr to AlCrCuNiZr favours the formation of intermetallic compound, enhances the yield strength, compressive strength and Vickers hardness, but degrades ultimate strain.
Investigation and characterisation of aluminium alloy foams with TiH2 as a foaming agent
Authors: Rajak D. K. , Kumaraswamidhas L. A. , Das S.
Published: January 2016

This article presents an account of experiments used to produce aluminium alloy foams by the melt route process using titanium hydride as a foaming agent. Powdered titanium hydride with content of 0.4–1.4% (mass fraction) was added to the molten pure aluminium and the foaming condition was controlled at 690°C (1274°F). In the process, homogeneous aluminium foams were produced with a calcium amount of 1.0–3.0% (mass fraction). The mechanical properties of the aluminium foams with diverse relative density were tested. The result indicates that the foaming agent is suitable for making small aperture aluminium foams with an average pore diameter of 1.2 mm.
Mechanical properties of austenitic stainless steel with high niobium contents
Authors: Okayasu M. , Wu S. , Noda K. , Lin D.-Y. , Yang S.-M.
Published: January 2016

To better understand the influence of the microstructural characteristics on the mechanical properties of Fe-Cr22-Ni25-Nb x austenitic stainless steel (ASS-Nb x), the mechanical properties were investigated. Nb addition was conducted with four different amounts: 0, 0.29, 0.58 and 0.86%. With the increasing Nb content, the mean grain size for the Fe-Cr-Ni-based alloys decreased, while the size of Nb precipitate increased. Owing to the different microstructural characteristics, their mechanical properties were altered. The highest tensile strength was obtained for ASS-Nb0.29 alloy. However, with the increasing Nb content in ASS-Nb0.29–0.86 alloys, the tensile strength decreases despite the grain refinement. The mechanical properties of the ASS-Nb alloys were influenced by the Nb precipitation hardening and the grain boundary cohesive strength, arising from the size of Nb precipitations.
Solvothermal fabrication of TiO2 nanosheet films on degradable Mg–Zn alloys
Authors: Hou S.
Published: January 2016

Anatase TiO2 nanosheet films were fabricated on Mg–Zn alloy substrates through a special solvothermal method, aiming to improve the corrosion resistance of degradable Mg–Zn alloy stents. In this novel synthesis process, absolute alcohol was used as solvent, and small amounts of hydrofluoric acid and NH4F aqueous solution were used to adjust the hydrolysis rate of titanium precursors and the crystal morphology of anatase TiO2, respectively. The NH4F played a key role in the growth of TiO2 nanosheets by supplying fluorine ions (F−). The anatase TiO2 films had a compact surface consisting of interleaving nanosheets with thickness of about 50 nm. In simulated body fluids, the corrosion current density ( Icorr) of Mg–Zn alloy substrates decreased from 789.5 to 24.4 µA cm−2, after being coated with the TiO2 nanosheet films.
Ethnic minorities and the land question in Nigeria
Authors: Arowosegbe Jeremiah O.
Published: January 2016

One of the most neglected aspects of the national question discourse in Nigeria is on the role of land as a site and source of conflicts, especially given the increasing demand for its redistribution and reform in the periods before and after the implementation of the structural adjustment programme. This study discusses land as a crucial aspect of the national question discourse in Nigeria. It examines the question of how colonialism – through its policies and programmes as well as the administrative structures and political systems put in place by the colonial state – introduced new complications and dimensions to the land question, mainly through the creation and development of contradictions in colonial and postcolonial Nigeria. Drawing on data generated from focus group discussions and oral interviews carried out across the locations with pronounced incidences of land-based conflicts in the six states across South-Western Nigeria, it examines the impact of economic considerations in the ethnically motivated conflicts in Nigeria over land from 1999 to 2015. It establishes the contradictions and injustices characterising the articulation of the citizenship question vis-à-vis various ethnic majorities and minorities as well as historically dominant minorities, especially indigenes and settlers in Nigerian history and politics; and how these generate violent ethnic protests, struggles and other divisive consequences. Tapping into ethnicity, migration and other issues underlying intergroup polarisation, it discusses the conflicts between Hausa–Fulani pastoralists and indigenous Yoruba farmers in South-Western Nigeria as an illustration of the contradictions underpinning citizenship and the prevailing frameworks of land ownership in Africa.
A note on “Regularity lemma for distal structures”
Authors: Simon Pierre
Published: January 2016

In a recent paper, Chernikov and Starchenko prove that graphs defined in distal theories have strong regularity properties, generalizing previous results about graphs defined by semi-algebraic relations. We give a shorter, purely model-theoretic proof of this fact, though with no explicit bounds.
A theorem of Lohwater and Piranian
Authors: Danielyan Arthur
Published: January 2016

By a well-known theorem of Lohwater and Piranian, for any set

E
E

on

|

z

|

=
1

|z|=1

of type

F
σ

F_\sigma

and of measure zero there exists a bounded analytic function in

|

z

|

>
1

|z|>1

which fails to have radial limits exactly at the points of

E
E

. We show that this theorem is an immediate corollary of Fatou’s interpolation theorem of 1906.
Nanoscopic cell-wall architecture of an immunogenic ligand in Candida albicans during antifungal drug treatment
Authors: Lin Jia , Wester Michael J. , Graus Matthew S. , Lidke Keith A. , Neumann Aaron K.
Published: January 2016

The cell wall of Candida albicans is composed largely of polysaccharides. Here we focus on β-glucan, an immunogenic cell-wall polysaccharide whose surface exposure is often restricted, or “masked,” from immune recognition by Dectin-1 on dendritic cells (DCs) and other innate immune cells. Previous research suggested that the physical presentation geometry of β-glucan might determine whether it can be recognized by Dectin-1. We used direct stochastic optical reconstruction microscopy to explore the fine structure of β-glucan exposed on C. albicans cell walls before and after treatment with the antimycotic drug caspofungin, which alters glucan exposure. Most surface-accessible glucan on C. albicans yeast and hyphae is limited to isolated Dectin-1–binding sites. Caspofungin-induced unmasking caused approximately fourfold to sevenfold increase in total glucan exposure, accompanied by increased phagocytosis efficiency of DCs for unmasked yeasts. Nanoscopic imaging of caspofungin-unmasked C. albicans cell walls revealed that the increase in glucan exposure is due to increased density of glucan exposures and increased multiglucan exposure sizes. These findings reveal that glucan exhibits significant nanostructure, which is a previously unknown physical component of the host– Candida interaction that might change during antifungal chemotherapy and affect innate immune activation.