bluuebunny/crossref_metadata_2025_split huggingface dataset:
Analysis of wave scattering from 2D curved metasurfaces using Floquet and Fourier series expansions
Authors: Khatami Maryam S. , Dehmollaian Mojtaba , Yousefi Leila 
Published: April 2021

AbstractAn efficient technique for calculating the scattering from curved metasurfaces using the extinction theorem in conjunction with the Floquet and Fourier series expansions is presented. Here, we treat the two‐dimensional metasurfaces that have transversal polarizabilities with no variation along the y‐axis. The boundary conditions at the metasurface are given by the generalized sheet transition conditions (GSTCs) whose susceptibilities are given in an arbitrary local coordinate system. First, we use the extinction theorem to provide integral equations of the scattering problem. The integral equations involve the Green's functions, tangential electric and magnetic fields and their normal derivatives in regions above and below the metasurface. Then, we employ the Floquet theorem that gives us the analytical periodic Green's functions of each region. Next, we employ the Fourier theorem to expand the tangential fields in terms of unknown Fourier coefficients. The GSTCs and the integral equations provide equations to be solved for the unknowns. The method can calculate scattering from both periodic and non‐periodic metasurfaces. The technique is used to analyse different applied problems such as carpet cloaking, illusion, and radar echo width reduction. The method is fast and accurate and can efficiently treat metasurfaces with electrically large curved geometries with dimensions as large as 120 times the wavelength.
Microwave intracavitary applicator using 434 MHz conformal patch antennas for hyperthermia treatment of gynaecological cancers
Authors: Rajendran Tharrini , Arunachalam Kavitha 
Published: April 2021

AbstractFeasibility of a 434 MHz microwave intracavitary applicator with conformal patch antennas is presented for hyperthermia treatment of gynaecological cancers. 3D numerical modelling was used to design a 434 MHz resonant conformal rectangular patch on a cylindrical alumina substrate. A conformal array applicator designed using four conformal patch antennas was evaluated in muscle tissue phantom. Applicator measurements indicated that the conformal patch resonated at 434 MHz with power reflection coefficient ρ < −35 dB, penetration depth of 12 mm at 434 MHz and −10 dB bandwidth >40 MHz. Normalised power deposition in the applicator transverse (XY) plane yielded 25% Effective Field Size (EFS) of 180 and 175 mm2 in simulation and measurement, respectively, for excitation of single conformal patch. The 25% EFS for excitation of two antennas was 500 and 510 mm2 in simulation and measurement, respectively. Simulations and measurements suggest that the 434 MHz intracavitary microwave applicator with conformal patch antennas could be used to deliver adjustable and localised power deposition at the target sparing the surrounding healthy tissues.
Understanding the enhanced electrorheological effect of reduced graphene oxide‐supported polyaniline dielectric nanoplates by a comparative study with graphene oxide as the support core
Authors: Yuan Jinhua , Wang Yudong , Xiang Liqin , Zhao Xiaopeng , Yin Jianbo 
Published: April 2021

AbstractGraphene has attracted scientific interest as a substrate or additive for developing high‐performance stimuli‐responsive materials. Research on graphene‐based polymer dielectric composites has shown an enhanced electroresponsive electrorheological (ER) effect. However, the mechanism behind the enhanced electroresponse is still incompletely understood. Here, an investigation was performed into dielectric polarization and the ER effect of reduced graphene oxide‐supported polyaniline nanoplates by comparing them with pure granular polyaniline and graphene oxide‐supported polyaniline nanoplates based on dielectric spectroscopy and rheologic analysis. We discovered that both anisotropic morphology and electrical properties have dominant roles in the enhanced ER effect of reduced graphene oxide‐supported polyaniline nanoplates, whereas only anisotropic morphology has a dominant role in the enhanced ER effect of graphene oxide‐supported polyaniline nanoplates. The analysis also showed that reduced graphene oxide‐supported polyaniline nanoplates have a good ER response to both DC and AC electric field actions in the wide shear rate region. This is highly desirable for practical engineering applications. Therefore, the analysis reveals the reason for the enhanced ER effect of reduced graphene oxide‐supported polyaniline nanoplates and also may provide a guide for designing high‐performance ER materials for practical engineering applications by combining the advantages of conducting a reduced graphene oxide core and ER active shell.
Seamless switching power sharing control method in a hybrid DC‐AC microgrid by the isolated two‐stage converter based on SST
Authors: Li Yue , Peng Yonggang , Wang Xiaoming 
Published: April 2021

AbstractTo facilitate the application of various renewable generations as well as diversified loads, hybrid DC/AC microgrids have aroused widespread interest; however, direct access of different types of sources and loads to the utility through multiple converters may be inefficient. In addition, with the complexity growth of the system, the stable and efficient operation puts forward new requirements for the isolation protection and more intelligent control. Facing these problems, the isolated two‐stage converter topology based on solid state transformer (SST) is designed and the automatic seamless switching power sharing control strategy is proposed. The proposed topology replaces the conventional passive transformer with dual‐active‐bridge converter (DABC) to realize voltage matching and galvanic isolation for higher controllability and less volume occupation. Constant ratio control method is adopted for DABC to operate as an ideal DC transformer. Further, AC frequency and DC voltage are measured as characterizations of power level to adjust the transferred power of the converter. Through the non‐directional strategy, bidirectional power support and decentralized cooperation are realized, and the capacity and sensitivity of microgrids are considered. The stability of the proposed control strategy is analyzed and the feasibility is verified by several real‐time hardware‐in‐loop experiments.
Parameter estimation and CRB analysis of 1‐bit colocated MIMO radar
Authors: Liu Bingfan , Chen Baixiao , Yang Minglei 
Published: April 2021

AbstractThe increasing demand for low‐cost and low‐power radars has led to the emergence of 1‐bit sampling technology. 1‐bit sampling technology is introduced in a multiple‐input and multiple‐output (MIMO) radar that has many advantages such as a high degree of freedom and flexible transmit beam pattern. The authors’ theoretical derivation shows that after 1‐bit quantisation, the received signal can be expressed as a linear combination of infinite components, which include the original component and high‐order components that can be regarded as interference terms. On this basis, the signal‐to‐noise‐ratio (SNR) loss after 1‐bit sampling at a low SNR is 1.96 dB. Furthermore, the Cramér‐Rao bound (CRB) of a MIMO radar with 1‐bit sampling is derived. In the derivation, the concept of 1‐bit equivalent noise is proposed. At low SNRs, the equivalent noise power is π/2 (1.96 dB) times the original noise power, which is consistent with a previous derivation. Numerical simulations showed the feasibility of traditional algorithms for a MIMO radar with 1‐bit sampling and the correctness of the authors’ derivation.
A Question of Timing: 10-year Retrospective Analysis on the Use of Antenatal Steroids for Imminent Preterm Birth
Authors: Matlac Dieter , Jonassen Sinje , Fortmann Mats Ingmar , Rody Achim , Bossung Verena 
Published: April 2021

Abstract
Objective Antenatal steroids improve the neonatal outcome if they are
administered within a therapeutic window of seven days before preterm birth.
The aim of this study was to evaluate the timing of antenatal steroids for
imminent preterm birth at a single center in Germany.
Material and Methods A 10-year retrospective analysis of 843 preterm
births between 24/0 and 33/6 weeks was performed from
January 2008 to December 2017 at a German university hospital. We evaluated
the timing of antenatal steroids according to the indication for their
application. Descriptive statistics and binomial regression were performed
to analyze factors influencing the timing of antenatal steroid
administration.
Results Of 843 preterm births below 34 weeks included in our study,
752 pregnant women received antenatal steroids (89.2%). Only
301/843 women (35.7%) gave birth within the optimal window
of 7 days after antenatal steroids. 91/843 women (10.8%) did
not receive steroids. 130/843 women (15.4%) only received
one dose, 76/843 (9.0%) gave birth within 8 to 14 days, and
245/843 (29.1%) more than 14 days later. In a binomial
regression model, preterm premature rupture of membranes (OR 3.40,
95% CI 1.81 to 6.39, p<0.001), fetal growth restriction (OR
3.27, 95% CI 1.63 to 6.58, p=0.001), and preeclampsia (OR
2.83, 95% CI 1.37 to 5.83, p=0.005) were positively
associated with optimal timing.
Conclusion Two thirds of women with preterm birth before 34 weeks
received antenatal steroids outside the optimal therapeutic window. Further
research is needed to achieve an optimal effect of antenatal steroids on
neonatal outcome and to reduce untimely as well as unnecessary
interventions.
Collaborative decision-making of wind-storage combined power generation system based on a variety of improved evaluation methods
Authors: Liu Jicheng , Bao Hongyan 
Published: April 2021

Wind power enterprises and energy storage companies have combined to form a wind-storage supply chain. Choosing a wind-storage combined power generation system will help companies make faster and better decisions and increase the value of cooperation in the wind-storage supply chain. Based on industry characteristics, 22 indexes that affect the collaborative decision-making of wind-storage combined power generation systems are selected, and an index evaluation system based on the interpretative structure model is designed. The entropy method is used to determine the index weight. Three collaborative decision-making models are designed, namely, a collaborative decision-making model based on the entropy weight method–fuzzy comprehensive evaluation method, a collaborative decision-making model based on the entropy method–TOPSIS, and a collaborative decision-making model based on fuzzy TOPSIS. The reliability of the model is verified through comparative analysis. At the same time, development suggestions in six aspects are put forward. This article provides a reference for collaborative decision-making between wind power enterprises and energy storage companies in the wind-storage supply chain.
At the request of the authors, this article is being retracted effective 2 June 2021.
Experimental and numerical analysis of Tm2+ excited-states dynamics and luminescence in CaX
2 (X = Cl, Br, I)
Authors: Plokker M P , van der Knijff I C , de Wit A V , Voet B , Woudstra T , Khanin V , Dorenbos P , van der Kolk E 
Published: April 2021

Abstract
The prospect of using Tm2+-doped halides for luminescence solar concentrators (LSCs) requires a thorough understanding of the temperature dependent Tm2+ excited states dynamics that determines the internal quantum efficiency (QE) and thereby the efficiency of the LSC. In this study we investigated the dynamics in CaX
2:Tm2+ (X = Cl, Br, I) by temperature- and time-resolved measurements. At 20 K up to four distinct Tm2+ emissions can be observed. Most of these emissions undergo quenching via multi-phonon relaxation below 100 K. At higher temperatures, only the lowest energy 5d–4f emission and the 4f–4f emission remain. Fitting a numerical rate equation model to the data shows that the subsequent quenching of the 5d–4f emission is likely to occur initially via multi-phonon relaxation, whereas at higher temperatures additional quenching via interband crossing becomes thermally activated. At room temperature only the 4f–4f emission remains and the related QE becomes close to 30%. Possible reasons for the quantum efficiency not reaching 100% are provided.
Supersolid-like states in a two-dimensional trapped spin–orbit-coupled spin-1 condensate
Authors: Adhikari S K 
Published: April 2021

Abstract
We study supersolid-like states in a quasi-two-dimensional trapped Rashba and Dresselhaus spin–orbit (SO) coupled spin-1 condensate. For small strengths of SO coupling γ (γ ⪅ 0.75), in the ferromagnetic phase, circularly-symmetric (0, ±1, ±2)- and (∓1, 0, ±1)-type states are formed where the numbers in the parentheses denote the angular momentum of the vortex at the center of the components and where the upper (lower) sign correspond to Rashba (Dresselhaus) coupling; in the antiferromagnetic phase, only (∓1, 0, ±1)-type states are formed. For large strengths of SO coupling, supersolid-like superlattice and superstripe states are formed in the ferromagnetic phase. In the antiferromagnetic phase, for large strengths of SO coupling, supersolid-like superstripe and multi-ring states are formed. For an equal mixture of Rashba and Dresselhaus SO couplings, only a superstripe state is found. All these states are found to be dynamically stable and hence accessible in an experiment and will enhance the fundamental understanding of crystallization onto radially periodic states in solids.
Conversion coefficients from absorbed dose to tissue to the newly proposed ICRU/ICRP operational quantities for radiation protection for beta reference radiation qualities
Authors: Behrens Rolf 
Published: April 2021

Abstract
The International Commission on Radiation Units and Measurements (ICRU) has, jointly with the International Commission on Radiological Protection (ICRP), recently proposed a set of new operational quantities for radiation protection in ICRU report 95. ICRU/ICRP supplied conversion coefficients for mono-energetic betas but not for beta reference radiation qualities defined by the International Organization for Standardization (ISO) in ISO 6980. Therefore, in this work, conversion coefficients from absorbed dose to tissue at a depth of 0.07 mm in a slab phantom to the newly proposed operational quantities are determined for beta reference radiation qualities. Finally, the impact of the newly proposed quantities on primary and calibration laboratories and on users and manufacturers of dosemeters is investigated, the latter by having a close look at the expected change of the response of dosemeters.
Targeted defect analysis in VCSEL oxide windows using 3D slice and view
Authors: Sun X , Rickard W D A , Ironside C N , Kostakis I , Missous M , Powell D , Anjomshoaa A , Meredith W 
Published: April 2021

Abstract
We report on high resolution analysis of vertical cavity surface emitting lasers (VCSELs) to detect and assess defects in sub-surface layers. We employ a focussed ion beam scanning electron microscope (FIB-SEM) to sputter and image successive cross sections (slice and view technique) in order to produce a 3D reconstruction of the oxide aperture region. High resolution images and measurements of the multilayers and oxide apertures of VCSEL devices were obtained. The process took ∼2.5 h and produced over 270 slice SEM images for a device volume of approximately 13.2 × 16.0 × 13.8 μm3, with a voxel size of 50 nm. On-wafer, single mode VCSEL devices with high and low output powers were analysed to compare their oxide apertures and distributed Bragg reflector (DBR) layer structures. It was found that the low output power VCSEL had DBR layer defects and a 41.8% reduction of effective oxide aperture area, explaining the lower power obtained. The results provide evidence that oxide aperture area and structural defects are major factors that affect the optical output power of VCSEL devices. Outcomes in this work show FIB-SEM slice and view is a valuable method for 3D reconstruction of VCSEL devices, which enables top view, cross-sectional view and angled view of the whole device region as well as designated structures such as oxide aperture or structural defects in various layers. This work demonstrates a promising technique with high resolution (50 nm) 3D imaging for analysis of complex semiconductor devices.
Ultrarelativistic electrons in counterpropagating laser beams
Authors: Lv Q Z , Raicher E , Keitel C H , Hatsagortsyan K Z 
Published: April 2021

Abstract
The dynamics and radiation of ultrarelativistic electrons in strong counterpropagating laser beams are investigated. Assuming that the particle energy is the dominant scale in the problem, an approximate solution of classical equations of motion is derived and the characteristic features of the motion are examined. A specific regime is found with comparable strong field quantum parameters of the beams, when the electron trajectory exhibits ultrashort spike-like features, which bears great significance to the corresponding radiation properties. An analytical expression for the spectral distribution of spontaneous radiation is derived in the framework of the Baier–Katkov semiclassical approximation based on the classical trajectory. All the analytical results are further validated by exact numerical calculations. We consider a non-resonant regime of interaction, when the laser frequencies in the electron rest frame are far from each other, avoiding stimulated emission. Special attention is devoted to settings when the description of radiation via the local constant field approximation fails and to corresponding spectral features. Periodic and non-periodic regimes are considered, when lab frequencies of the laser waves are always commensurate. The sensitivity of spectra with respect to the electron beam spread, focusing and finite duration of the laser beams is explored.
Dependence of the polytropic index of plasma on magnetic field
Authors: Kim June Young , Go Geunwoo , Hwang Y S , Chung Kyoung-Jae 
Published: April 2021

Abstract
Determination of the polytropic index of plasma in a magnetic field provides description of plasma physics ranging from laboratory plasma in the Earth to black hole in the Universe. Accordingly, a lot of efforts have been devoted to revealing the dependence of polytropic index of plasma on magnetic field. A recent experiment performed in a magnetic nozzle reported the dependency of the polytropic index on the magnetic field strength in that the polytropic index changes from 5/3 to unity with decreasing the magnetic field strength. In this letter, we show that the polytropic index of plasma does not depend on magnetic field if the radial electric field is sustained. The polytropic index is measured to be close to 2, higher than the previously reported value, regardless of the change in the strength and configuration of magnetic field.
Structural, electronic and optical characterization of Eu
3+/Dy
3+ single and co-doped Mg2P2O7 phosphors
Authors: Mahajan Rubby , Prakash Ram , Choudhary R. J. , Phase D. M. 
Published: April 2021

Abstract
Eu3+/ Dy3+ single and co-doped magnesium pyrophosphate phosphors were synthesized via solution combustion route. The resulted phosphor has a monoclinic crystal structure with space group B21/c. The lattice parameter of the sample is refined using ‘Full Prof software’. x-ray photoemission spectroscopy (XPS) result reveals that dysprosium and europium present in a trivalent valence state. Valence band spectra (VBS) result indicates that 6 features present in a single doped sample and 8 features present in a co-doped sample. The photoluminescence studies reveal that the combination of Eu3+ and Dy3+ emissions give tuneable emission from red to pink to yellowish-white under UV excitation. The energy transfer mechanism from Dy3+ to Eu3+ is confirmed from photoluminescence spectra and life time curves. The optical band gap of the prepared samples is obtained to be in the range of 5.02–5.40 eV. The synthesized material has conventional application in solid-state lighting under UV-excitation.
Spectroscopic characterization of thermally evaporated oxovanadium(IV) tetraphenylporphyrin thin films
Authors: Makhlouf M M , Farooq M U , Ataalla Nahla N , Afifi Mohamed B 
Published: April 2021

Abstract
Thin films of oxovanadium(IV) tetraphenylporphyrin (VOTPP) were prepared on quartz substrates by using thermal evaporation technique. The surface morphology and x-ray diffraction analysis of the VOTPP thin films were investigated. The micrographs of atomic force microscope of the films reveled nanostructure formation. The spectroscopic measurements of the transmittance and reflectance for VOTPP films were recorded in the spectrum range 190 –2000 nm, and from which many optical constants such as refractive index, extinction index and dielectric constant were determined. The absorption spectrum of VOTPP film showed an intense Soret band, two electronic quasi-states (Q-band) and two other bands (N and L) extended over the UV–Vis spectral region. The type of electronic transition bands of VOTPP films showed indirect allowed. The values of optical energies band-gaps were determined to be 1.89, 2.15 and 2.61 eV, in addition to Urbach tail energy was 0.044 eV. Furthermore, Wemple-DiDomenico model was applied to a normal dispersion region of the refractive index spectrum in order to extract many dispersion parameters such single oscillator energy, dispersion energy, infinite dielectric constant and lattice dielectric constant. The present spectroscopic results reveals that the thin films of VOTPP could be utilized as promising absorbing layers in energy conversion devices.
A three-dimensional vertex model for Drosophila salivary gland invagination
Authors: Durney Clinton H , Feng James J 
Published: April 2021

Abstract
During epithelial morphogenesis, force generation at the cellular level not only causes cell deformation, but may also produce coordinated cell movement and rearrangement on the tissue level. In this paper, we use a novel three-dimensional vertex model to explore the roles of cellular forces during the formation of the salivary gland in the Drosophila embryo. Representing the placode as an epithelial sheet of initially columnar cells, we focus on the spatial and temporal patterning of contractile forces due to three actomyosin pools: the apicomedial actomyosin in the pit of the placode, junctional actomyosin arcs outside the pit, and a supracellular actomyosin cable along the circumference of the placode. In an in silico ‘wild type’ model, these pools are activated at different times according to experimental data. To identify the role of each myosin pool, we have also simulated various in silico ‘mutants’ in which only one or two of the myosin pools are activated. We find that the apicomedial myosin initiates a small dimple in the pit, but this is not essential for the overall invagination of the placode. The myosin arcs are the main driver of invagination and are responsible for the internalization of the apical surface. The circumferential actomyosin cable acts to constrict the opening of the developing tube, and is responsible for forming a properly shaped lumen. Cell intercalation tends to facilitate the invagination, but the geometric constraints of our model only allow a small number of intercalations, and their effect is minor. The placode invagination predicted by the model is in general agreement with experimental observations. It confirms some features of the current ‘belt-and-braces’ model for the process, and provides new insights on the separate roles of the various myosin pools and their spatio-temporal coordination.