bluuebunny/crossref_metadata_2025 huggingface dataset:
Uplink sum rate analysis of multi‐user massive MIMO–OFDM/OQAM systems in Ricean fading
Authors: Singh Shivani , Singh Prem , Vasudevan Kasturi
Published: April 2020

This study investigates the uplink performance of offset quadrature amplitude modulation (OQAM)‐based orthogonal frequency division multiplexing (OFDM) waveform in single‐cell multi‐user massive multiple‐input multiple‐output (MIMO) systems over Ricean fading. An uplink training‐based minimum mean square error (MMSE) channel estimation by exploiting the inherent characteristics of OFDM/OQAM waveform is briefly presented. By leveraging the second‐order statistical characteristics of the intrinsic interference, the achievable uplink sum rates and corresponding closed‐form approximations are derived in the presence of MMSE channel estimate at the base station with zero‐forcing (ZF) and maximum‐ratio combining (MRC) receivers. Based on the above analytical results for the uplink rates, power scaling laws are also investigated. The effect of Ricean‐K factor on the achievable uplink sum rate is also examined analytically for both the MRC and ZF receivers. Numerical results compare the performance of OFDM/OQAM and classic cyclic‐prefix OFDM‐based massive MIMO systems and also validate the various analytical expressions derived in this work.
Broadband circularly polarised stacked antenna with sequential‐phase feed technique
Authors: Ding Kang , Hong Rentang , Guan Dongfang , Liu Li , Wu Yanjie
Published: April 2020

A broadband circularly polarised (CP) stacked antenna with a sequential‐phase feed technique is proposed in this study. The antenna contains a square ring that is encircled by four driven patches. The gap‐coupled feed method is used to transfer energy from the square ring to the driven patches. Moreover, four stacked patches are placed above the bottom layer to enhance the impedance and CP bandwidths. The measured results yield an impedance bandwidth of 33.6% (4.78–6.71 GHz) and a wide 3 dB axial ratio bandwidth of 19.4% (4.90–5.95 GHz) is obtained. The average gain is ∼9 dBi and the variation of gain is <1 dB within the CP bandwidth.
Power control method for improving efficiency of laser‐based wireless power transmission system
Authors: Zhou Weiyang , Jin Ke
Published: April 2020

Laser‐based wireless power transmission (LWPT) systems are one of the most promising systems in the long‐range wireless power transfer field. However, few studies have focused on the efficiency characteristics of LWPT systems. Therefore, most LWPT systems are open‐loop systems, making it difficult to best utilise their lasers and photovoltaic cells, thus preventing the system efficiency from being further improved. In this study, a closed‐loop power control method is proposed for LWPT systems to explore the best performance conditions for such systems. To this end, the efficiency characteristics of a system are investigated by means of theoretical analysis and experimental measurements. The results show that the duty cycle of the laser input current is one of the key factors for improving the system efficiency. Then, a dual closed‐loop controller, which includes an optimal duty cycle search algorithm, is proposed based on the obtained system characteristics. Finally, a small‐scale prototype is fabricated and tested in the laboratory to verify the effectiveness of the proposed power control method.
Photoconductivity kinetics of indium sulfofluoride thin films
Authors: Vygranenko Yuri , Fernandes Miguel , Vieira Manuela , Lavareda Guilherme , Nunes de Carvalho Carlos , Brogueira Pedro , Amaral Ana
Published: April 2020

Indium sulfofluoride is an amorphous wide-gap semiconductor exhibiting high sensitivity to UV radiation. This work reports on the kinetics of photoconductivity in indium sulfofluoride thin films along with their electrical and optical properties. The films were deposited by radio-frequency plasma-enhanced reactive thermal evaporation. The film characterization includes electrical, optical, and photoconductivity measurements. The films are highly transparent in the visible-infrared range due to an indirect bandgap of 2.8 eV. The spectral response measurements have revealed existence of the band tail states. The synthesized compound is highly resistive (∼200 MΩ-cm at 300 K) and exhibits extremely slow photocurrent relaxations. Photoconductivity kinetics was studied under various excitation conditions. A dependence of the photocurrent on the incident photon flux was also determined.
Peri implant bone resorption on microvascular free fibula flap: a radiographic retrospective study
Authors: Pelissier Emile , Desoutter Aline , Chaux-Bodard Anne-Gaëlle
Published: April 2020

Introduction: As the vascularization of the microvascular free fibula flap enables to maintain an osteogenic potential, osseointegrated implants have a 86% to 99% success rate. Thus, only few studies consider peri-implant bone resorption (PIBR). The aim of the study was to radiologically evaluate PIBR on fibula flaps. Materials and methods: Data were retrospectively collected. Gender, age, reason for interruptive mandibulectomy, previous radiotherapy, number of implants placed on the reconstruction, length and number of segments of the reconstruction, height of resorption were collected for each patient. Measurements were made on panoramic radiograph. Results: 85 clinical reports were reviewed for 39 retained. Peri-implant bone resorption was observed in 21 (53.9%) patients. The average age of the resorption group was 55.4 . All of the 5 patients with 4 or 5 implants on their reconstruction did not developed PIBR. 59.1% of patients with 1 segment reconstruction developed PIBR, 54.6% with 2 segments and 33.3% with 3 segments. Discussion: Age and poor oral hygiene appeared to be clearly more related to PIBR. An important number of implant (4 or 5) and a reconstruction with more than 1 segment seemed to decrease PIBR. Further studies are required to confirm these hypotheses.
Sunflower agronomy: 10 years of research in partnership within the “Sunflower” Technological Joint Unit (UMT) in Toulouse
Authors: Debaeke Philippe , Bret-Mestries Emmanuelle , Aubertot Jean-Noël , Casadebaig Pierre , Champolivier Luc , Dejoux Jean-François , Maury Pierre , Seassau Célia
Published: April 2020

In order to make more efficient plant breeding and gain in competitiveness, the sector of oil-protein crops decided to intensify agronomic research on sunflower crop. The “Sunflower” Joint Technological Unit (Unité Mixte Technologique (UMT) “Tournesol”, in French) was launched in the Toulouse area in 2006, associating closely INRA and Terres Inovia. First focused on improving oil production through an agronomic approach, the UMT was renewed in 2011 with a broader partnership and a more assertive orientation towards the development of decision-making tools. The objective of this paper is to highlight the relevance and productivity of this user-oriented research facility. The main results relate to (i) the co-construction of a simulation model (SUNFLO) that can be parameterized and manipulated by Terres Inovia engineers, (ii) the joint exploration of supra-field scales and new methods for agronomic diagnosis and yield forecasting based on remote sensing, (iii) the tuning and dissemination of operational decision rules, (iv) the production of essential knowledge on emergent and/or damaging fungal diseases, as well as on complex interactions between genotype, environment and crop management. After a concluding symposium in 2016, new requests for sunflower research were formulated by the participants. They also advocated for a diversification of crops to consider in order to better meet the needs of the whole oil-protein sector.
The dual pair (Uq(su(1,1)),oq1/2(2n)), q-oscillators, and Askey-Wilson algebras
Authors: Frappat Luc , Gaboriaud Julien , Ragoucy Eric , Vinet Luc
Published: April 2020

The universal Askey–Wilson algebra AW(3) can be obtained as the commutant of Uq(su(1,1)) in Uq(su(1,1))⊗3. We analyze the commutant of oq1/2(2)⊕oq1/2(2)⊕oq1/2(2) in q-oscillator representations of oq1/2(6) and show that it also realizes AW(3). These two pictures of AW(3) are shown to be dual in the sense of Howe; this is made clear by highlighting the role of the intermediate Casimir elements of each member of the dual pair Uq(su(1,1)),oq1/2(6). We also generalize these results. A higher rank extension of the Askey–Wilson algebra denoted AW(n) can be defined as the commutant of Uq(su(1,1)) in Uq(su(1,1))⊗n, and a dual description of AW(n) as the commutant of oq1/2(2)⊕n in q-oscillator representations of oq1/2(2n) is offered by calling upon the dual pair Uq(su(1,1)),oq1/2(2n).
Spin pumping and large field-like torque at room temperature in sputtered amorphous WTe2−x films
Authors: Fan Yihong , Li Hongshi , DC Mahendra , Peterson Thomas , Held Jacob , Sahu Protyush , Chen Junyang , Zhang Delin , Mkhoyan Andre , Wang Jian-Ping
Published: April 2020

We studied the spin-to-charge and charge-to-spin conversion at room temperature in sputtered WTe2−x (x = 0.8) (t)/Co20Fe60B20(6 nm) heterostructures. Spin pumping measurements were used to characterize the spin-to-charge efficiency, and the spin efficiency was calculated to be larger than ∼0.035. Second harmonic Hall measurements were carried out to estimate the charge-to-spin conversion ratio. We found that the system exhibits a large field-like torque (spin torque efficiency ∼0.1) and small damping-like torque (spin torque efficiency ∼0.001) compared to those reported for heavy metals. High-resolution transmission electron microscopy images show that the WTe2−x layer is amorphous, which may enhance the spin swapping effect by inducing large interfacial spin–orbit scattering, thus contributing to a large field-like torque.
Absolute stimulated Raman side scatter in direct-drive laser-produced plasmas
Authors: Short R. W.
Published: April 2020

Production of suprathermal electrons by stimulated Raman scattering (SRS) is a principal concern for contemporary direct-drive inertial confinement fusion experiments at the National Ignition Facility and similar systems since such electrons penetrate and preheat the target core, preventing efficient implosion. The higher temperatures and longer scale lengths in these experiments favor SRS over two-plasmon decay, which predominated in earlier experiments. In particular, current experiments are expected to exceed the threshold for absolute Raman side scatter, which would then dominate the interaction since it grows temporally until saturated by nonlinear mechanisms such as hot-electron production. Until recently, analyses of SRS side scatter have treated the case of a single laser beam incident on a plasma, but the direct-drive approach to laser fusion employs a multitude of beams to drive the implosion. Here, we present an analysis that can be applied to an arbitrary number of beams with varied angles of incidence and polarizations. In the case of a single beam, it allows a physically motivated derivation and verification of an analytic threshold formula. In the general case of multiple beams and arbitrary orientation and polarizations, the threshold is found by numerical integration of a set of first-order linear partial differential equations.
Decay rates of the compressible Hall-magnetohydrodynamic model for quantum plasmas
Authors: Xi Xiaoyu , Pu Xueke , Guo Boling
Published: April 2020

In this paper, the compressible Hall-magnetohydrodynamic model for quantum plasmas in three-dimensional whole space is considered. By using the Lp-Lq estimates and the Fourier splitting method, if the initial perturbation is small in H4 × H3 × H3 and bounded in the L1 norm, we obtain the time decay rates for low- and higher-order spatial derivatives of density, velocity, and magnetic field.
Synchronizability of directed networks: The power of non-existent ties
Authors: Daley Kevin , Zhao Kun , Belykh Igor V.
Published: April 2020

The understanding of how synchronization in directed networks is influenced by structural changes in network topology is far from complete. While the addition of an edge always promotes synchronization in a wide class of undirected networks, this addition may impede synchronization in directed networks. In this paper, we develop the augmented graph stability method, which allows for explicitly connecting the stability of synchronization to changes in network topology. The transformation of a directed network into a symmetrized-and-augmented undirected network is the central component of this new method. This transformation is executed by symmetrizing and weighting the underlying connection graph and adding new undirected edges with consideration made for the mean degree imbalance of each pair of nodes. These new edges represent “non-existent ties” in the original directed network and often control the location of critical nodes whose directed connections can be altered to manipulate the stability of synchronization in a desired way. In particular, we show that the addition of small-world shortcuts to directed networks, which makes “non-existent ties” disappear, can worsen the synchronizability, thereby revealing a destructive role of small-world connections in directed networks. An extension of our method may open the door to studying synchronization in directed multilayer networks, which cannot be effectively handled by the eigenvalue-based methods.
Origin of enhanced piezoelectric properties revealed through electric field driven studies in 0.94(Na0.5Bi0.5TiO3)−0.06(Ba0.85Ca0.15Ti0.9Zr0.1O3) ceramics
Authors: T Karthik , Rayaprol Sudhindra , Siruguri Vasudeva , Asthana Saket
Published: April 2020

A single phase 0.94(Na0.5Bi0.5TiO3)–0.06(Ba0.85Ca0.15Ti0.9Zr0.1O3) solid solution (i.e., BCZT-0.06) is prepared using a conventional solid-state sintering route with enhanced piezo and ferroelectric properties as compared to Na0.5Bi0.5TiO3 (NBT). In the context of understanding the origin of enhanced piezoelectric properties in a BCZT-0.06 specimen, electric field driven studies on different length scales, viz., global, local, and electronic structure, are carried out using x-ray/neutron diffraction, Raman scattering, and UV–Vis spectroscopic techniques. An analysis on different length scales of the electric field-driven BCZT-0.06 specimen displays minimum rhombohedral lattice distortion (δr), reduced homogeneous lattice strain (δ), octahedral strain (ζ), and pronounced Ti-cation displacement along the polar [111] direction as compared to parent NBT. The enhanced ferro and piezoelectric responses observed in the BCZT-0.06 specimen have been attributed to the ease of non-180° domain re-orientation, domain switching, and domain wall motion due to reduced strain coupled with a polarization extension mechanism.
Recent advances in high speed diffuse optical imaging in biomedicine
Authors: Applegate M. B. , Istfan R. E. , Spink S. , Tank A. , Roblyer D.
Published: April 2020

Diffuse optical imaging (DOI) is a label-free, safe, inexpensive, and quantitative imaging modality that provides metabolic and molecular contrast in tissue using visible or near-infrared light. DOI modalities can image up to several centimeters deep in tissue, providing access to a wide range of human tissues and organ sites. DOI technologies have benefitted from several decades of academic research, which has provided a variety of platforms that prioritize imaging depth, resolution, field-of-view, spectral content, and other application-specific criteria. Until recently, however, acquisition and processing speeds have represented a stubborn barrier to further clinical exploration and implementation. Over the last several years, advances in high-speed data acquisition enabled by high-speed digital electronics, newly available sources and detectors, and innovative new scanning methods have led to major improvements in DOI rates. These advances are now being coupled with new data processing algorithms that utilize deep learning and other computationally efficient methods to provide rapid or real-time feedback in the clinic. Together, these improvements have the potential to help advance DOI technologies to the point where major impacts can be made in clinical care. Here, we review recent advances in acquisition and processing speed for several important DOI modalities.
Properties of bulk scandium nitride crystals grown by physical vapor transport
Authors: Al-Atabi Hayder , Zheng Qiye , Cetnar John S. , Look David , Cahill David G. , Edgar James H.
Published: April 2020

In this study, the growth of scandium nitride (100) single crystals with high electron mobility and high thermal conductivity was demonstrated by physical vapor transport (PVT). Single crystals were grown in the temperature range of 1900 °C–2140 °C under a nitrogen pressure between 15 and 20 Torr. Single crystal tungsten (100) was used as a nearly lattice constant matched seed crystal. Growth for 20 days resulted in a 2 mm thick crystal. Hall-effect measurements revealed that the layers were n-type with a 300 K electron concentration and a mobility of 2.17 × 1021 cm−3 and 73 cm2/V s, respectively. Consequently, this ScN crystal had a low electrical resistivity, 3.94 × 10−5 Ω cm. The thermal conductivity was in the range of 51–56 W/m K, three times higher than those in previous reports for ScN thin films. This study demonstrates the viability of the PVT crystal growth method for producing high quality bulk scandium nitride single crystals.
Formation of silica-supported platinum nanoparticles as a function of preparation conditions and boron impregnation
Authors: Rani Sana , Byron Carly , Teplyakov Andrew V.
Published: April 2020

Preparation of supported metal nanoparticles for catalytic applications often relies on an assumption that the initially prepared wet-impregnated support material is covered with approximately a monolayer of adsorbed species that are shaped into the target nanoparticulate material with a desired size distribution by utilizing appropriate post-treatments that often include calcination and reduction schemes. Here, the formation and evolution of surface nanoparticles were investigated for wet-chemistry deposition of platinum from trimethyl(methylcyclopentadienyl)platinum (IV) precursor onto flat silica supports to interrogate the factors influencing the initial stages of nanoparticle formation. The deposition was performed on silicon-based substrates, including hydroxylated silica (SiO2) and boron-impregnated hydroxylated silica (B/SiO2) surfaces. The deposition resulted in the immediate formation of Pt-containing nanoparticles, as confirmed by atomic force microscopy and x-ray photoelectron spectroscopy. The prepared substrates were later reduced at 550 °C under H2 gas environment. This reduction procedure resulted in the formation of metallic Pt particles. The reactivity of the precursor and dispersion of Pt nanoparticles on the OH-terminated silica surface were compared to those on the B-impregnated surface. The size distribution of the resulting nanoparticles as a function of surface preparation was evaluated, and density functional theory calculations were used to explain the differences between the two types of surfaces investigated.
Control of the gyrotron filament power supplies for the experimental advanced superconducting tokamak
Authors: Xu Weiye , Xu Handong , Liu Fukun , Yan Xinsheng
Published: April 2020

The electron cyclotron heating system including four gyrotrons is being developed in the Institute of Plasma Physics, Chinese Academy of Sciences. The filament is an important part of the gyrotron, which is used to heat the cathode. The gyrotron output power can be controlled by adjusting the filament power. We have developed the filament power control and measurement system using Labview. The filament characteristics were tested using this power control system. The test results show that the filament current can be fitted with the e-exponential function of the filament voltage. It can be seen that as the voltage increases, the filament resistance gradually increases. We have developed a new “burst” function to prevent the beam current from dropping too fast, which is conducive to long pulse stable operation of the gyrotrons.
Room temperature multiferroic properties of electrospun gallium ferrite nanofibers
Authors: Zhao Z. M. , An F. , Tian F. G. , Zhang Y. , Zhu Q. F. , Chen L. , Zhong G. K. , Xie S. H.
Published: April 2020

Gallium ferrite (GaFeO3) is a promising multiferroic material for multifunctional device applications. Compared with bulk and thin film materials, nanofibers are possible to magnify the magnetostriction or piezoelectric effect due to their large length–diameter ratio, thus improving the performance of the material. In this work, GaxFe2 – xO3 (GFO) nanofibers have been synthesized by sol-gel based electrospinning. With the increasing Fe ion content, the room-temperature antiferromagnetic to ferromagnetic transition of GFO nanofibers has been confirmed by magnetic hysteresis loops; and the corresponding temperature dependent magnetization curves show that the ferromagnetic–paramagnetic transition temperature (Tc) is above room temperature and increases from around 292 K to above 400 K. Ferroelectricity of GFO nanofibers has been confirmed by second harmonic generation and piezoresponse force microscopy. Magnetoelectric (ME) coupling has been further measured by dual amplitude resonance tracking piezoresponse force microscopy and sequential excitation piezoresponse force microscopy under an in-plane external magnetic field. The newly developed SE-PFM method reduces the crosstalk of morphology, confirming that no obvious intrinsic ME coupling appears in the GFO nanofibers.
Exploring conduction mechanism and photoresponse in P-GaN/n-MoS2 heterojunction diode
Authors: Moun Monika , Singh Rajendra
Published: April 2020

Mixed-dimensional heterostructures have shown their potential in electronic devices. However, their functionality is limited by a complete understanding of the contacts and the current transport behavior. Here, we explore the electrical properties of the P-n heterojunction diode fabricated using p-type gallium nitride and layered molybdenum disulfide. The resulting P-n diode is rectifying in nature with current rectification of three orders of magnitude. The careful choice of Ohmic contacts on both the semiconductors reveals distinctly rectifying behavior of the heterojunction diode. The as-fabricated diode is tested at various temperatures, and the conduction mechanism in the device is analyzed based on the temperature dependent electrical characterizations. In addition, photoresponse characterization reveals that the P-n heterojunction is highly sensitive to a 405 nm laser with a high responsivity of 444 A/W at a reverse bias voltage of 5 V and shows photovoltaic behavior. The heterojunction diode acts as a self-powered photodetector. Our findings show the potential of the MoS2/GaN heterojunction in highly efficient photodetector applications.
Effects of aspect ratio on electron loss mechanisms and plasma uniformity in cylindrical inductively coupled plasma
Authors: Hao Zeyu , Hua Yue , Song Jian , Ren Chunsheng
Published: April 2020

The aspect ratio (AR) of discharge geometry is an important parameter in view of inductively coupled plasma (ICP) source design. AR is defined as the ratio of chamber radius (R) and chamber height (L). The effects of the AR on plasma parameters and uniformity are investigated in a 2 MHz ICP source. The argon discharge is performed in two chambers of AR = 0.72 and 0.35 with different heights, and the effects of AR on electron loss mechanisms are studied using a global model. The results show a tendency for generation of higher density plasma with better uniformity in the case of AR = 0.72 at 0.5–2 Pa. The difference in electron density is caused by the differences in the volume. The observations on plasma uniformity are explained by the study of the electron loss mechanism. The accumulation of electrons is weakened by axial diffusion at the chamber center in the case of AR = 0.72. The difference in plasma uniformity between the two chambers diminishes with the increase in the gas pressure from 0.5 to 2 Pa, which results from the fact that the electron diffusion along the axial direction becomes more difficult. At higher pressures from 5–10 Pa, the ambipolar diffusion loss of electrons to the chamber wall becomes more difficult with the increase in pressure due to frequent collisions. Therefore, the electron accumulation in the discharge center is more evident in the chamber with AR = 0.72, which deteriorates the plasma uniformity. The above study can give a reference to the design of cylindrical ICP sources for practical applications.
Dissociation dynamics of carbon dioxide cation (CO2+) in the C2Σg+ state via [1+1] two-photon excitation
Authors: Zhou Zhengfang , Feng Shaowen , Hua Zefeng , Li Zhen , Chen Yang , Zhao Dongfeng
Published: April 2020

The dissociation dynamics of CO2+ in the C2Σg+ state has been studied in the 8.14–8.68 eV region by [1+1] two-photon excitation via vibronically selected intermediate A2Πu and B2Σu+ states using a cryogenic ion trap velocity map imaging spectrometer. The cryogenic ion trap produces an internally cold mass selected ion sample of CO2+. Total translational energy release (TER) and two-dimensional recoiling velocity distributions of fragmented CO+ ions are measured by time-sliced velocity map imaging. High resolution TER spectra allow us to identify and assign three dissociation channels of CO2+ (C2Σg+) in the studied energy region: (1) production of CO+(X2Σ+) + O(3P) by predissociation via spin–orbit coupling with the repulsive 14Πu state; (2) production of CO+(X2Σ+) + O(1D) by predissociation via bending and/or anti-symmetric stretching mediated conical intersection crossing with A2Πu or B2Σu+, where the C2Σg+/A2Πu crossing is considered to be more likely; (3) direct dissociation to CO+(A2Π) + O(3P) on the C2Σg+ state surface, which exhibits a competitive intensity above its dissociation limit (8.20 eV). For the first dissociation channel, the fragmented CO+(X2Σ+) ions are found to have widely spread populations of both rotational and vibrational levels, indicating that bending of the parent CO2+ over a broad range is involved upon dissociation, while for the latter two channels, the produced CO+(X2Σ+) and CO+(A2Π) ions have relatively narrow rotational populations. The anisotropy parameters β are also measured for all three channels and are found to be nearly independent of the vibronically selected intermediate states, likely due to complicated intramolecular interactions in the studied energy region.
Flying spot thermography: Quantitative assessment of thermal diffusivity and crack width
Authors: Salazar Agustín , Mendioroz Arantza , Oleaga Alberto
Published: April 2020

Flying spot thermography is an efficient thermographic non-destructive technique that has been widely applied to detect surface breaking cracks on large parts in a fast way. It consists in heating the sample surface with a laser spot that moves at a constant speed and recording the surface temperature with an infrared camera. The presence of a crack hinders heat propagation and produces a discontinuity in the temperature at the surface, that is, the signature of the crack. In this tutorial, we address two quantitative applications of flying spot thermography: the measurement of thermal diffusivity and the determination of the width of cracks. We present derivations of the analytical expressions of the surface temperature, from which specific methods for the quantitative assessment of thermal diffusivity and crack width are introduced. We show that the methodology is also valid for the complementary configuration, with a static laser spot exciting a moving specimen, as in industrial production chains. The methodology is illustrated with experimental data on sound and artificially cracked samples. We conclude the tutorial by discussing the limitations and future perspectives of this technique.
Metal–Organic Frameworks (MOFs)-boosted filtration membrane technology for water sustainability
Authors: Gu Qilin , Ng How Yong , Zhao Dan , Wang John
Published: April 2020

Metal–Organic Frameworks (MOFs), which are well-known for their highly controllable level of porosity, large specific surface area, and structural diversity, have been regarded as a class of promising materials for gas storage/separation, liquid separation, energy storage, and conversion. Recently, the applications of MOFs in water technology and sustainability have drawn increasing attention in the research community, although they are much under-investigated. For applications in water technologies, a rational integration of MOFs and bulk substrates is a necessary engineering strategy to improve their stability and recyclability and avoid the potential secondary contamination. In this mini overview, MOF-boosted filtration membrane technology is critically looked into and the current state-of-the-art is discussed. We focus on the membrane filtration technology promoted by MOFs for water treatment, with particular emphasis on the permeability-selectivity trade-off and membrane fouling. In this connection, the configuration and fabrication of MOF-boosted membranes are visited, followed by those MOF-mediated membranes, such as high-permeable membranes, adsorptive membranes, antifouling membranes, and catalytic membranes, where the multi-functionalities are among the key characteristics. A summary is made on the controlling features of these MOF-boosted membranes for water and wastewater treatment, together with the particular challenges and future perspectives.
A feed-forward measurement scheme for periodic noise suppression in atomic magnetometry
Authors: O’Dwyer Carolyn , Ingleby Stuart J. , Chalmers Iain C. , Griffin Paul F. , Riis Erling
Published: April 2020

We present an unshielded, double-resonance magnetometer in which we have implemented a feed-forward measurement scheme in order to suppress periodic magnetic noise arising from, and correlated with, the mains electricity alternating current line. The technique described here uses a single sensor to track ambient periodic noise and feed forward to suppress it in a subsequent measurement. This feed forward technique has shown significant noise suppression of electrical mains-noise features of up to 22 dB under the fundamental peak at 50 Hz, 3 dB at the first harmonic (100 Hz), and 21 dB at the second harmonic (150 Hz). This technique is software based, requires no additional hardware, and is easy to implement in an existing magnetometer.
Polymorphic phase boundary in piezoelectric oxides
Authors: Garcia José Eduardo , Rubio-Marcos Fernando
Published: April 2020

The design of phase boundaries has now become a consolidated strategy to improve the functional properties of piezoelectric oxides because of the unique properties that may be obtained in their vicinity. In particular, polymorphic phase boundaries (PPBs) have attracted significant interest in recent years because they represent a significant breakthrough in terms of enhanced piezoelectric activity of lead-free piezoelectric oxides. PPBs are temperature-driven phase transitions where both intrinsic and extrinsic contributions maximize, thereby enhancing the macroscopic properties of piezoelectric materials. This tutorial discusses potassium–sodium–niobate-based systems as model materials to reveal some of the most relevant advances in the design of PPBs through compositional modifications. We focus on how PPBs can be modulated by engineered doping and also discuss the direct relation between PPBs and the enhancement of piezoelectric activity. Finally, we briefly describe the main experimental techniques for detecting PPBs.
Development of a stagnation streamline model for thermochemical nonequilibrium flow
Authors: Hong Qizhen , Wang Xiaoyong , Hu Yuan , Sun Quanhua
Published: April 2020

A stagnation streamline model incorporating quantum-state-resolved chemistry is proposed to study hypersonic nonequilibrium flows along the stagnation streamline. This model is developed by reducing the full Navier–Stokes equations to the stagnation streamline with proper approximations for equation closure. The thermochemical nonequilibrium is described by either the state-to-state approach for detailed analysis or conventional two-temperature models for comparison purpose. The model is validated against various data, and nearly identical results are obtained as compared with those from full field computational fluid dynamics data. In addition, the calculated distributions agree well with the measurement data of a shock tube experiment for the dissociation and vibrational relaxation of O2, including the distributions of species mole fractions and vibrational temperature of the first excited state of O2 molecules. Furthermore, the results with the state-resolved chemistry show that the flow within a shock layer exhibits a strong thermochemical nonequilibrium behavior, which is beyond the capability of commonly used two-temperature models to correctly evaluate the dissociation rate and the associated reaction energy. The present model is also employed to calculate the nonequilibrium re-entry flow along the stagnation streamline for a five-species air mixture as an example to demonstrate the model capability. It is found that both species and internal energy are in a nonequilibrium state, especially the vibrational distributions are strongly deviated from the Boltzmann distribution right behind the bow shock and near the wall surface. The results demonstrate that the proposed stagnation streamline model is very useful to understand thermochemical nonequilibrium phenomena in hypersonic flows.
A handle on the scandal: Data driven approaches to structure prediction
Authors: Narasimhan Shobhana
Published: April 2020

Structure–property relationships play a central role in condensed matter physics, chemistry, and materials science. However, the problem of predicting the structure of a material, given its chemical composition, remains immensely challenging. Here, we review some of the progress that has been made in this area for both crystalline materials and atomic clusters. Early work consisted of heuristic rules-of-thumb or structure maps using descriptors that were obtained largely by inspection. Increasingly, these approaches are being expanded to use descriptors that have been obtained by applying machine learning techniques to big data containing information from the experiment and/or first principles calculations. Improved techniques for global optimization in the multi-dimensional coordinate space have also led to major advances in the field.
Effects of nitrogen fertilisation and irrigation on seed yield and yield components of signal grass (Urochloa decumbens)
Authors: Canto M. W. , Pancera E. J. , Neto A. Barth , Bremm C. , Vier P. U. , Costa A. C. S.
Published: April 2020

The effects of nitrogen (N) fertiliser rate and irrigation on seed yield and its components were evaluated for signal grass (Urochloa decumbens (Stapf) R.D. Webster; syn. of Brachiaria decumbens Stapf) cv. Basilisk in a field experiment in Umuarama, Paraná, Brazil. Two water regimes (irrigated and non-irrigated) and four nitrogen (N) fertiliser rates (0, 25, 50 and 75 kg ha–1) were applied to perennial signal grass crops in a split-plot randomised complete block design with three replications. In two consecutive harvests, favourable rainfall resulted in irrigation having limited influence on most measurements, and the combined application of irrigation and N fertiliser did not improve seed yield. Compared with the nil N, the highest N application rate significantly increased seed yield for the first crop (266 vs 498 kg ha–1) and the second crop (104 vs 286 kg ha–1). Nitrogen fertilisation significantly increased number of seed per area, reproductive tiller density and plant biomass at harvest for the first and second crops. Harvest index, 1000-seed weight, reproductive tiller weight, number of spikelets per panicle and number of seeds per panicle were unaffected by N rate. Harvest index ranged from 1.10% to 3.63% and 1000-seed weight from 2.15 to 3.36 g. There were no treatment effects on number of days to flowering or anthesis. Fertilisation with 75 kg N ha–1 for the first crop and 50–75 kg N ha–1 for the second crop maximised signal grass seed yield.
Effects of plant population and row spacing on grain yield of aerial-sown and drill-sown rice
Authors: Dunn B. W. , Dunn T. S. , Mitchell J. H. , Brinkhoff J.
Published: April 2020

Objective guidelines about plant population are essential to ensure that yield potential of rice grain is not compromised. Drill-sowing of rice is increasing in popularity in many rice-growing regions of the world in response to a requirement for increased water productivity, but little information is available on row-spacing widths required to maximise grain yield potential. This research investigated the impacts of plant population on grain yield and yield components for aerial- and drill-sown rice, and the effects of row-spacing width for drill-sown rice grown in a temperate environment. Ten aerial-sown and five drill-sown experiments were conducted in south-eastern Australia over three seasons using four semi-dwarf rice varieties. Plant populations ranged from 7 to 396 plants m–2.
Plant populations as low as 30 plants m–2 were able to achieve grain yields >12 t ha–1 but only when the plants were uniformly distributed. At a population of ~100 plants m–2, the impact of plant-stand distribution was negligible. Grain yield was maintained across a large range of plant populations, mainly through compensatory effects of more tillers per plant and more grains per panicle at lower plant populations.
For aerial-sown rice, maximum grain yield (up to 14.9 t ha–1) was always achieved with a minimum plant population of 100 plants m–2, and likewise for drill-sown rice provided the row spacing was ≤27 cm. At equivalent plant populations, 36-cm row spacing produced lower grain yield than narrower row spacings. When large gaps existed between plants within the rows, neighbouring plants could not compensate for the gap at the wider 36-cm row spacing, and grain yield was reduced. A practical optimal plant population of 100–200 plants m–2 was found to be suitable for the semi-dwarf varieties used in this study for both aerial- and drill-sowing methods.
Biology of Brassica tournefortii in the northern grains region of Australia
Authors: Mahajan Gulshan , Singh Rajandeep , Chauhan Bhagirath S.
Published: April 2020

Brassica tournefortii Gouan. (wild turnip, WT) has become a problematic weed in the no-till production systems of the northern grains region of Australia. Experiments were undertaken using different biotypes of B. tournefortii to examine its phenology, emergence and seedbank persistence. Biotypes were obtained from paddocks of barley (Hordeum vulgare L.) (WT1 and WT9) and chickpea (Cicer arietinum L.) (WT1/17 and WT2/17). Fresh seeds initially had high dormancy rates and persisted for a short period on the surface. Seedbank persistence increased with burial depth, with 39% of seeds remaining for WT1 and 5% for WT9 after 30 months at 2 cm depth. Persistence of buried seeds varied across biotypes; WT1/17 seedlings also emerged in the second growing season from 2 cm depth. Compared with buried seeds, seedlings readily emerged from the surface (in March–June following increased rainfall) within 6 months of planting. Emergence was greatest on the surface and varied between biotypes and tillage systems; the highest rate recorded was ~14%. Multiple cohorts were produced between February and October. No-till systems produced higher emergence rates than conventional tillage systems. Seedlings of B. tournefortii did not emerge from 5 cm soil depth; therefore, diligent tillage practices without seedbank replenishment could rapidly reduce the presence of this weed. A soil-moisture study revealed that at 25% of water-holding capacity, B. tournefortii tended to produce sufficient seeds for reinfestation in the field. Brassica tournefortii is a cross-pollinated species, and its wider emergence time and capacity to produce enough seeds in a dry environment enable it to become widespread in Australia. Early cohorts (March) tended to have vigorous growth and high reproduction potential. This study found B. tournefortii to be a poor competitor of wheat (Triticum aestivum L.), having greater capacity to compete with the slow-growing crop chickpea. Therefore, control of early-season cohorts and use of rotations with a more vigorous crop such as wheat may reduce the seedbank. The information gained in this study will be important in developing better understanding of seed ecology of B. tournefortii for the purpose of developing integrated management strategies.
Connectivity and plasticity determine collagen network fracture
Authors: Burla Federica , Dussi Simone , Martinez-Torres Cristina , Tauber Justin , van der Gucht Jasper , Koenderink Gijsje H.
Published: April 2020

Significance

Collagen fibers are the main components of the extracellular matrix, a fibrous scaffold that sets the shape and stiffness of tissues in the human body and protects them from mechanical failure. The relation between the hierarchical and heterogeneous structure of collagen networks and their fracture behavior is still missing. Prior studies focused on tendons, where collagen forms highly aligned bundles, but many tissues such as skin contain disordered collagen networks. Here, we show that fracture of disordered collagen networks is controlled by their connectivity rather than by the single-fiber properties. We further show that structural plasticity can delay network failure. Our findings are useful in understanding how tissues fail and in the design of stronger network-based materials.
The diachrony of participles in the (pre)history of Greek and Hittite
Authors: Grestenberger Laura
Published: April 2020

This article discusses two case studies of diachronic “voice flipping” in which the syntax of a participle appears to change from active or “subject-oriented” to passive (Ancient Greek ‑menosto Modern Greek ‑menos) and from resultative/stative to active (Proto-Indo-European *-nt-; Hittite ‑ant‑ vs. Ancient Greek ‑nt‑). While the first type of change is the result of a diachronic reanalysis by which a functional projection (VoiceP) is lost, the second type in fact adds an active Voice head. Both changes are the result of the simultaneous availability of a stative and an eventive reading in deverbal adjectival forms and could belong to a larger “participle cycle”. However, unlike in other changes usually discussed under the label “cycle”, unidirectional economy principles do not apply in these cases. Rather, these cases provide evidence that some types of morphosyntactic change, especially those related to event and argument structure, are driven by reanalysis of the feature content of functional heads under local structural ambiguity.
Cross-dialectal productivity of the Spanish subjunctive in
nominal clause complements
Authors: Schwenter Scott A. , Hoff Mark R.
Published: April 2020

We performed a large-scale corpus study of the
subjunctive across Argentine, Mexican, and Peninsular Spanish, in
order to determine possible differences in productivity across
dialects. Our data (N = 6,822) from the
web/dialects section of Davies’
(2016–) Corpus del Español were
collected through random sampling of 22 matrix verb governors. All
three dialects were significantly different from one another in
type:token ratio, whereas only Spain differed from the others in
terms of hapax legomena:type ratio. Furthermore,
only eight verbs showed the same behavior across all dialects.
Subjunctive productivity thus varies by both dialect and governor,
thereby revealing the critical importance of both inter- and
intra-dialectal variation for the correct analysis of
morphosyntactic phenomena. The conditioning of the variation across
dialects, nevertheless, was similar: mixed-effects logistic
regression in R revealed that negated governors and cases of
non-coreferentiality between main and subordinate clause subjects
select significantly more subjunctive.
Mood selection in a contact variety
Authors: Bove Kathryn
Published: April 2020

Researchers have noted unique qualities of
Yucatec Spanish with regard to phonetics, syntax, and pragmatics
(Bove, 2019; Hoot, 2016; Michnowicz, 2009, 2012; Solomon, 1996, 1999). The objective of this study is
twofold: to describe mood in Yucatec Spanish and to identify how
bilingual and monolingual speakers’ mood selection differs. Results
indicate that volitional predicates categorically license
subjunctive while alternation exists under emotive and epistemic
predicates. This alternation highlights statistically significant
differences between monolingual and bilingual speakers of Yucatec
Spanish (p = 0.01 and 0.04 respectively). Emotive
predicates pattern with previous accounts of Mexican Spanish (e.g.,
Lope Blanch, 1989),
but unanticipated subjunctive selection in epistemic assertions,
interrogatives, and statements with past temporal reference
highlight a difference between monolingual and bilingual
participants.
Did you say peso or
beso?
Authors: Pollock Matthew
Published: April 2020

The Perceptual Assimilation Model for L2 speakers
and the Speech Learning Model make predictions about the difficulty
of acquisition based on pre-existing boundaries in learners’ L1s.
This study focuses on differences between voice onset time in
English and Spanish stops, especially related to perceptual cues.
Participants – 10 Spanish native speakers and 131 L1 English
learners of Spanish at various levels – categorized 120 stimuli
containing Spanish minimal pairs beginning with voiced and voiceless
stops and the distractor /r/. Classifications varied based on
acoustic manipulations of VOT, the original phone, and proficiency
level. While VOT is an important determiner in perceptual
boundaries, and learners can acquire L2 distinctions (although often
not achieving native-like patterns), additional acoustic differences
affect sound identification.
Sheísmo in Montevideo Spanish
Authors: Michnowicz Jim , Planchón Lucía
Published: April 2020

Studies have documented an ongoing change from
/ʒ/ to /ʃ/ in Rioplatense Spanish, and research
indicates that the change to /ʃ/ is complete for young speakers of
Buenos Aires (BA) Spanish. However, sheísmo in the
neighboring country of Uruguay has not been thoroughly studied. The
present study finds that, unlike in BA, the change to /ʃ/ is not yet
complete in Montevideo, as determined by persistent sex differences
among young speakers (Cameron,
2011; Chang,
2008), and differences in voicing rates between
/ʒ/~/ʃ/and phonologically voiceless /s/, indicating that observed
voicing is not due solely to gestural overlap (Rohena-Madrazo, 2015).
Uruguay is at least one generation behind BA for this change,
distinguishing the Spanish spoken in the two regions.
Decolonial sociolinguistics gestures of Andean Quechua-Spanish
bilingual college students promoting Quechua
Authors: Kenfield Yuliana
Published: April 2020

Andean college students in Cusco, Peru, struggle
to overcome sociolinguistic discrimination against Quechua-Spanish
bilingualism during their pursuit of higher education. To examine
this situation and possibilities for change, I employed a
participatory method, photovoice (Wang & Burris, 1994) within a
community-based participatory research framework, to facilitate
bilingual college students’ exploration of Quechuan practices in
their university. Findings of this participatory study explain how
bilingual participants contributed to community critical awareness
of Quechua-Spanish bilingual ideologies in Cusco when presenting
their visual metaphors during photo interventions. Participants
shared personal experiences to maintaining their Quechua language
and shared their proposals for encouraging their university to
create a fertile terrain for bilingualism, rooting out ideologies of
deficits toward Quechua, and promoting Quechuan practices in
college.