bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of Aluminum Sulfate on the Hydration of Tricalcium Aluminate
Authors: Jing Xiuyan , Zhang Yan , Liu Huaqing , Liu Jialong , Kong Sen
Published: April 2021

Aluminum sulfate (AS), as the main composition of alkali-free accelerator, was widely used to accelerate the setting and promote the early strength in the sprayed concrete. In this study, effect of AS on the hydration reaction of C3A was investigated, which is one of the most important cement clinker minerals in the early age of cement hydration. The hydration reaction and products of C3A-AS system were characterized with hydration heat test, X-ray diffraction, thermogravimetric analysis, scanning electron microscope, and thermodynamic modeling. Results indicate that AS could hinder the hydration reaction in the very early age but then accelerate C3A hydration by producing SO4-AFm, OH-AFm, and gibbsite. The findings are expected to provide theoretical guidance for the product research and engineering application of alkali-free accelerator.
Theoretical Study on the Size Effect of the Rate Characteristics of Concrete Cubes Compressive Strength
Authors: Zhou Hongyu , Liu Yanan , Zhou Yun , Tang Qi
Published: April 2021

In order to study the effect of size effect and rate correlation on the mechanical properties of concrete, a total of 228 concrete cube test blocks of three sizes (70, 100 and 150mm) were tested and studied under four strain rates (10−5,10−4,10−3,10−2/s). The test results show that under the same strain rate, the peak stress of concrete decreases with the increase of the size. Under the same size, the peak stress of concrete increases with the increase of strain rate. Experimental data were used to verify and modify Weibull size effect equation based on statistics and Bazant size effect equation based on fracture mechanics. The experimental data fit well with the equation, and the size effect theory of concrete strength with correlation of holdup is established.
Modification of the Constitutive Model of Concrete Material Considering the Effect of Structural Size
Authors: Zhou Hongyu , Tang Qi , Zhou Yun , Liu Yanan
Published: April 2021

As the size of the structure increases, the size effect on the mechanical properties of the structure cannot be ignored. During the service period, the reinforced concrete structure will be affected by the size effect. At present, there is no item concerning material size effect in the current regulations in my country. This paper summarizes the existing size effect theory and finds a function that expresses the size effect of concrete. The peak strength size effect coefficients of domestic and foreign researchers are analyzed, and the logarithmic function form is used to calculate the peak strength size effect coefficients obtained by various researchers. The average value was fitted. We found the size effect coefficient of the ultimate strain of concrete based on the test results, and took the size effect coefficient of the ultimate strain of the concrete with a cube side length of 150 mm as one for analysis. Finally we revised the constitutive relationship of concrete.
Analysis of Factors Influencing the Performance of Fiber Reinforced Concrete
Authors: He Jingjing , Bi Yali , Zhang Yong , Lu Haodan , Fan Lihao , Zhao Kunlong , Wu Wenbo
Published: April 2021

As a new type of building material, fiber reinforced concrete (FRC) has been widely used in the field of construction engineering. Further analysis of the mechanism of discontinuous fiber improving concrete performance is the key to the preparation and rational application of high performance FRC. The mechanisms of crack resistance, tensile strength and bending resistance of discontinuous fiber reinforced concrete were analysed. The influence factors of fiber reinforced concrete performance were discussed. The results show that fiber length, fiber section shape, fiber volume fraction, fiber orientation and fiber length diameter ratio have significant effects on the performance of concrete. The existence of the fiber group effect leads to the increase of the critical volume fraction of the fiber. The improvement of the tensile strength of the composite was slow down, and it increased nonlinearly with the change of the volume fraction of the fiber. The utilization rate of the fiber decreased greatly. The fiber hybrid effect was the important factor affecting the improvement of concrete performance by fibers. The effective way of discontinuous fiber improving concrete performance is to reduce fiber group effect and use the positive fiber hybrid effect.
Research on Performance of BRA Modified Asphalt
Authors: Zhang Zhen
Published: April 2021

For estimating the performance indexes of Buton rock asphalt (BRA) modified asphalt and the influence of different Buton asphalt content on the property of BRA modified asphalt, an indoor pitch performance index experiment was carried out. The test study uses Buton asphalt as the modifier, and the percentage of Buton asphalt relative to the total asphalt is used as the mixing ratio (namely internal mixing method), with 5% as the interval, select 10%, 15%, 20%, 25% and 30% five blending ratios to prepare BRA modified pitch. In addition, related tests will be done on the prepared BRA modified asphalt, and the high temperature property, low temperature property and durability of Buton asphalt modified pitch were evaluated. The analysis of the test results shows that the function of the BRA modified asphalt prepared by adding the base asphalt to Buton asphalt has changed. With the increase of Buton asphalt content, the high temperature property of BRA modified asphalt is significantly improved, but the low temperature property decreases with the increase of the content, and the durability performance is roughly the same as that of the unmodified matrix asphalt.
Experimental Study on Cold Bending and Temperature Change of Toughened Glass
Authors: Zhang Xide , Yin Xiaoqi
Published: April 2021

In order to study the temperature strain of the insulating tempered glass under certain cold bending test, cold bending test and temperature test were carried out on the glass plate. Taking the self-made cold-formed steel frame as the tool and the hollow laminated tempered glass as the object, the cold bending test of the glass was carried out. The results show that the stress of each measuring point increases linearly with the increase of cold bending displacement, and the maximum principal stress appears at the end of the loader near the loading point of the outer sheet glass. The temperature changes test of the glass shows that the stress of each measuring point is linear with the increase in temperature difference. The results show that the maximum principal stress appears near the constrained angle steel on the displacement side of the upper edge of the outer sheet glass; the stress changes greatly during the short-term cooling test, and the tensile and compressive stresses transform each other. The internal stress produced by cold bending is coupled with the maximum principal stress produced by temperature load, and the maximum principal stress appears at the lower edge constraint of the loading displacement side.
Chloride Binding Capacity of Portland Cement System with Different Content of Tricalcium Aluminate
Authors: Liu Huaqing , Zhang Yan , Liu Jialong , Kong Sen , Feng Zixia
Published: April 2021

The binding of chloride ion has been reported as an effective way to reduce the risk of steel corrosion induced by the utilization of marine sources. In this study, effect of tricalcium aluminate (C3A) on chloride binding capacity of Portland cement paste was investigated; the setting time, compressive strength, and fluidity of cement-C3A system were also examined. The reaction mechanism of C3A and chloride ions was studied by X-ray diffraction (XRD) and thermo gravimetric analysis (TGA). The results showed that addition of C3A in cement paste could increase the compressive strength not only at the early age but also at the late age. The setting time was shortened obviously and the fluidity was reduced. The main reason was that fast hydration of C3A could hasten the formation of ettringite to consume free water, and also promote the hydration of the system. Furthermore, addition of C3A in cement paste could greatly promote the chloride binding capacity, and the main reason was due to the promoted formation of FS in hydrates. The investigation was expected to provide experience in promoting the chloride binding capacity of cement system.
The Controllable Turbulence Generator Based on Piezoelectric Actuation and Its Mechanical Performance Analysis
Authors: Wang Shuai , Zhou Shichen , Zhou Bo , Xue Shifeng
Published: April 2021

Piezoelectric material is a kind of material that can perform electric-force conversion. Various actuators made of its inverse piezoelectric effect have been widely used in intelligent structures. In this paper, a piezoelectric actuated turbulence generator is designed, the design concept and working principle are introduced, the mechanical behavior of the piezoelectric structure is analyzed by using the finite element method, and the influence of electrical load on the deformation of the piezoelectric structure along different directions is considered. This paper can provide some theoretical basis for the design and analysis of turbulence generator.
Electroelastic Analysis of Fiber Reinforced Piezoelectric Composite Beam based on Finite Element Method
Authors: Ma Xiao , Zhou Bo , Xue Shifeng
Published: April 2021

Piezoelectric composites have been increasingly used in engineering structures due to their excellent flexibility, durability and robustness to damage. In this paper, the electroelastic behaviors of the fiber reinforced piezoelectric composite (FRPC) beam are analyzed by the finite element method. The stress, vertical displacement and electric potential of the FRPC beam subjected to a uniform load are studied. The effect of the fiber volume fraction on the electroelastic behaviors of the FRPC beam is discussed in detail. The results reveal that the stress is independent of the fiber volume fraction, but the fiber volume fraction has a great influence on the vertical displacement and electric potential. The results obtained in the present paper may be useful references for the application and design of the piezoelectric actuators and sensors.
Polarization singularity analysis of Mueller-matrix invariants of optical anisotropy of biological tissues samples in cancer diagnostics
Authors: Ushenko V O , Trifonyuk L , Ushenko Y A , Dubolazov O V , Gorsky M P , Ushenko A G
Published: April 2021

An approach of azimuthally invariant Mueller-matrix description of the formation of polarization singularities networks of object fields of optically anisotropic biological tissues is proposed. The main formation scenarios of the topological polarization-singular structure of the boundary field of networks of optically anisotropic cylinders are determined by means of computer simulation. In order to assess the polarization-singular structure of the object field of real biological tissues, an original Mueller-matrix method of statistical analysis of the number of L and C points has been developed.
Review on the recent progress in the development of fluorescent probes targeting enzymes
Authors: Rajapaksha Asanka Amith , Fu Yi-Xuan , Guo Wu Yingzheng , Liu Shi-Yu , Li Zhi-Wen , Xiong Cui-Qin , Yang Wen-Chao , Yang Guang-Fu
Published: April 2021

Enzymes are very important for biological processes in a living being, performing similar or multiple tasks in and out of cells, tissues and other organisms at a particular location. The abnormal activity of particular enzyme usually caused serious diseases such as Alzheimer’s disease, Parkinson’s disease, cancers, diabetes, cardiovascular diseases, arthritis etc. Hence, nondestructive and real-time visualization for certain enzyme is very important for understanding the biological issues, as well as the drug administration and drug metabolism. Fluorescent cellular probe-based enzyme detectionin vitroandin vivohas become broad interest for human disease diagnostics and therapeutics. This review highlights the recent findings and designs of highly sensitive and selective fluorescent cellular probes targeting enzymes for quantitative analysis and bioimaging.
Traps at the hBN/WSe2 interface and their impact on polarity transition in WSe2
Authors: Ali Fida , Ahmed Faisal , Taqi Muhammad , Mitta Sekhar Babu , Ngo Tien Dat , Eom Deok Joon , Watanabe Kenji , Taniguchi Takashi , Kim Hyoungsub , Hwang Euyheon , Yoo Won Jong
Published: April 2021

Semiconducting two-dimensional (2D) materials-based devices usually exhibit inferior electrical performance compared to their theoretical predictions, which is mainly attributed to the presence of high density of interfacial defect induced trap states within the bandgap of 2D materials. It is pertinent to control the density of interface traps (D
it) and identify their respective energy levels inside the band gap of the 2D materials to understand the tailored device performance. Here, we report the large modulation of D
it by electrical gating and varying the channel thickness of tungsten diselenide (WSe2) placed on ultra-clean hexagonal boron nitride (hBN) gate insulator in a metal–insulator–semiconductor structure, which is revealed by performing multi-frequency capacitance and conductance measurements. Analysis of the 2D hBN/WSe2 interface reveals that with the increase of WSe2 thickness, D
it at the midgap of WSe2 is reduced to 6 × 109 cm−2 eV−1, which is less than D
it reported for SiO2/Si interface (∼1010 cm−2 eV−1). Furthermore, by increasing thickness and applying gate voltage, D
it distribution is systematically modulated inside the WSe2 band gap from valence band edge to mid-gap to conduction band edge, thereby changing the Fermi level of WSe2, and inducing versatile device polarity. Our results show that D
it and its spatial energy distribution within the thickness tailored WSe2 band gap primarily control polarity modulation in WSe2.
Moiré phonons in twisted MoSe2–WSe2 heterobilayers and their correlation with interlayer excitons
Authors: Parzefall Philipp , Holler Johannes , Scheuck Marten , Beer Andreas , Lin Kai-Qiang , Peng Bo , Monserrat Bartomeu , Nagler Philipp , Kempf Michael , Korn Tobias , Schüller Christian
Published: April 2021

We report about the investigation of twisted MoSe2 homo- and MoSe2–WSe2 heterobilayers by means of low-frequency Raman spectroscopy (LFRS) and low-temperature micro photoluminescence (µPL). In room-temperature LFRS experiments on both, twisted MoSe2 homobilayers and twisted MoSe2–WSe2 heterobilayers, we observe moiré phonons, i.e. folded acoustic phonon modes due to the moiré superlattice. In the heterobilayers, we can identify moiré phonons of both materials, MoSe2 and WSe2. While the twist angles for the homobilayers are relatively precisely known from the applied tear-and-stack preparation method, the twist angles of the heterobilayers have to be determined via second-harmonic-generation microscopy on monolayer regions of the samples, which has significant uncertainties. We show that by the moiré phonons of the heterobilayers, the relative twist angles can be determined on a local scale with much higher precision. We apply our technique for the investigation of a large area H-type (twist angle θ = 60∘ + δ) MoSe2–WSe2 heterobilayer. These investigations show that spatial regions, which can be identified to be atomically reconstructed (i.e. δ = 0∘) by the observation of an interlayer shear mode in LFRS experiments, exhibit a strong, momentum-allowed interlayer-exciton signal in low-temperature µPL. On the contrary, regions, where moiré phonons are observed, i.e. which can be identified to be rigidly twisted by a misalignment angle in the range of

5
°

≲
|
δ
|
≲

6
°

, exhibit no significant interlayer-exciton signals.
The role of flexural coupling in heat dissipation from a two-dimensional layered material to its hexagonal boron nitride substrate
Authors: Ong Zhun-Yong , Zhang Gang , Zhang Yong-Wei
Published: April 2021

Understanding the limits of phononic heat dissipation from a two-dimensional layered material (2DLM) to its hexagonal boron nitride (h-BN) substrate and how it varies with the structure of the 2DLM is important for the design and thermal management of h-BN-supported nanoelectronic devices. We formulate an elasticity-based theory to model the phonon-mediated heat dissipation between a 2DLM and its h-BN substrate. By treating the h-BN substrate as a semi-infinite stack of harmonically coupled thin plates, we obtain semi-analytical expressions for the thermal boundary conductance (TBC) and interfacial phonon transmission spectrum. We evaluate the temperature-dependent TBC of the N-layer 2DLM (graphene or MoS2) on different common substrates (h-BN vs. a-SiO2) at different values of N. The results suggest that h-BN is substantially more effective for heat dissipation from MoS2 than a-SiO2 especially at large N. To understand the limitations of the our stack model, we also compare its predictions in the

N
=
∞

limit to those of the more exact atomistic Green’s function model for the graphite–BN and molybdenite–BN interfaces. Our stack model provides clear insights into the key role of the flexural modes in the TBC and how the anisotropic elastic properties of h-BN affect heat dissipation.
Graphene quantum dots as shallow traps in a high-k polymer matrix for bipolar resistive switching
Authors: Liu Yiwen , Wang Yongfei , Li Xiao , Hu Zhizhi
Published: April 2021

Graphene quantum dots (GQDs) have broad applications in electronic and photonic devices. As a typical zero-dimensional material, a GQD has a stronger quantum confinement effect than do two-dimensional graphene or one-dimensional graphene nanoribbons, and provide efficient charge trapping sites, which are useful in nonvolatile memory devices. Here, we report the fabrication of 30-nm-thick GQD-blended high-k polymer cyanoethylated pullulan (CEP) thin films sandwiched between an Al top electrode and an indium tin oxide (ITO) bottom electrode. Bipolar resistive switching behavior was observed with a low onset (−1.7 V) and offset (1.3 V) voltages. The resistive switching behavior originates from shallow traps that induce space-charge-limited current conduction. The morphology, crystallinity and photoluminescence of the GQDs were also studied by atomic force microscopy, transmission electron microscopy, and photoluminescence spectroscopy. The CEP/GQD blended films may have applications in nonvolatile resistive memory devices.
The 2021 flexible and printed electronics roadmap
Authors: Bonnassieux Yvan , Brabec Christoph J , Cao Yong , Carmichael Tricia Breen , Chabinyc Michael L , Cheng Kwang-Ting , Cho Gyoujin , Chung Anjung , Cobb Corie L , Distler Andreas , Egelhaaf Hans-Joachim , Grau Gerd , Guo Xiaojun , Haghiashtiani Ghazaleh , Huang Tsung-Ching , Hussain Muhammad M , Iniguez Benjamin , Lee Taik-Min , Li Ling , Ma Yuguang , Ma Dongge , McAlpine Michael C , Ng Tse Nga , Österbacka Ronald , Patel Shrayesh N , Peng Junbiao , Peng Huisheng , Rivnay Jonathan , Shao Leilai , Steingart Daniel , Street Robert A , Subramanian Vivek , Torsi Luisa , Wu Yunyun
Published: April 2021

This roadmap includes the perspectives and visions of leading researchers in the key areas of flexible and printable electronics. The covered topics are broadly organized by the device technologies (sections 1–9), fabrication techniques (sections 10–12), and design and modeling approaches (sections 13 and 14) essential to the future development of new applications leveraging flexible electronics (FE). The interdisciplinary nature of this field involves everything from fundamental scientific discoveries to engineering challenges; from design and synthesis of new materials via novel device design to modelling and digital manufacturing of integrated systems. As such, this roadmap aims to serve as a resource on the current status and future challenges in the areas covered by the roadmap and to highlight the breadth and wide-ranging opportunities made available by FE technologies.
Formation of superscar waves in plane polygonal billiards*
Authors: Bogomolny Eugene
Published: April 2021

Polygonal billiards constitute a special class of models. Though they have zero Lyapunov exponent their classical and quantum properties are involved due to scattering on singular vertices with angles

≠
π

/

n

with integer n. It is demonstrated that in the semiclassical limit the multiple singular scattering on such vertices, when optical boundaries of many scatters overlap, leads to the vanishing of quantum wave functions along straight lines built by these scatters. This phenomenon has an especially important consequence for polygonal billiards where periodic orbits (when they exist) form pencils of parallel rays restricted from the both sides by singular vertices. Due to the singular scattering on boundary vertices, waves propagated inside a periodic orbit pencil tend in the semiclassical limit to zero along pencil boundaries thus forming weakly interacting quasi-modes. Contrary to scars in chaotic systems, the discussed quasi-modes in polygonal billiards become almost exact for high-excited states and for brevity they are designated as superscars. Many pictures of eigenfunctions for a triangular billiard and a barrier billiard which have clear superscar structures are presented in the paper. Special attention is given to the development of quantitative methods of detecting and analysing such superscars. In particular, it is demonstrated that the overlap between superscar waves associated with a fixed periodic orbit and eigenfunctions of a barrier billiard is distributed according to the Breit-Wigner distribution typical for weakly interacting quasi-modes. For special sub-class of rational polygonal billiards called Veech polygons where all periodic orbits can be calculated analytically it is argued and checked numerically that their eigenfunctions are fractal in the Fourier space.
Controlling mid-infrared plasmons in graphene nanostructures through post-fabrication chemical doping
Authors: Paulillo Bruno , Bareza Nestor Jr , Pruneri Valerio
Published: April 2021

Engineering the doping level in graphene nanostructures to yield controlled and intense localized surface plasmon resonance (LSPR) is fundamental for their practical use in applications such as molecular sensing for point of care or environmental monitoring. In this work, we experimentally study how chemical doping of graphene nanostructures using ethylene amines affects their mid-infrared plasmonic response following the induced change in electrical transport properties. Combining post-fabrication silanization and amine doping allows to prepare the surface to support a strong LSPR response at zero bias. These findings pave the way to design highly doped graphene LSPR surfaces for infrared sensors operating in real environments.
Programmable surface anisotropy from polarization-driven azopolymer reconfiguration
Authors: Salvatore Marcella , Borbone Fabio , Reda Francesco , Maddalena Pasqualino , Oscurato Stefano Luigi
Published: April 2021

The ability to accurately realize complex textures is of great relevance for tailoring surface-driven functionalities as wettability, adhesion and light diffraction. The fabrication of superficial micro-textures, in a simple and cost-effective way, is high desiderable in this framework. A versatile technique for surface micropatterning is based on reconfiguration of photosensitive azobenzene-containing polymers, in which a macroscopic light-induced motion of polymer chains, fueled by the photo-isomerizing azobenzene molecules, allows the controlled optical reshaping of prestructured superficial micro-textures. Here, azopolymer surfaces, prepatterned with an array of discrete cylindrical micropillars, are reconfigured through a polarization-driven large-scale surface deformation until achieving superficial gratings with programmable amplitude, orientation and periodicity. The high degree of structural surface anisotropy, the possibility to program the directionality of such anisotropy from the reconfiguration of basic pristine surfaces, and the simplicity of the optical setup, make the proposed structuration method attractive for versatile and cost-effective surface patterning.
An investigation of efficient muon production for use in muon catalyzed fusion
Authors: Spencer Kelly R , Hart Lucy J F , Rose Steven J
Published: April 2021

We model the energy cost of producing muons for use in muon catalyzed fusion and show that by careful design the cost can be reduced by a factor of 2.5 below current values. This is done by recapturing the kinetic energy of waste particles and generating heat through tritium breeding. When put together with the modeling of muon catalyzed fusion we estimate that electrical output/electrical input of 14% can be achieved currently.
The SparSpec algorithm and the application to the detection of spatial periodicities in tokamaks: using memory with relaxation
*
Authors: Testa D , Carfantan H , Perrone L M
Published: April 2021

A common problem in many complex physical systems is the determination of pulsation modes from irregularly sampled time-series, and there is a wealth of signal processing techniques that are being applied to post-pulse and real-time data analysis in such complex systems. The aim of this report is studying the problem of detecting in real-time spatial periodicities in the spectrum of magnetic fluctuations in tokamaks, for which optimization of the algorithm run-time is essential. The main tool used hereafter will be the SparSpec algorithm, initially devised for astrophysical purposes and already applied to the analysis of magnetic fluctuation data in various tokamaks, both currently or previously operating (JET, TCV, Alcator C-mod) and under construction (ITER, DTT). For JET, the baseline version of the SparSpec algorithm, dubbed SS-H2, already regularly runs in real-time on a 1 ms clock for detecting Toroidal Alfvén Eigenmodes using synchronously-detected magnetic perturbation. It was noted that the solution is only slowly changing in time as the background plasma typically also slowly evolves. Therefore, as a specifically real-time acceleration tool, we will focus on the use of a memory with relaxation scheme, whereby solutions obtained at previous time points are used to provide weighted input constraints for the solution at the current time point. Use of the measurement uncertainties to weight the data, the spectral window and the ensuing penalization criterion (dubbed the SS-V5ν0 algorithm) is reported in a companion work. The behaviour of the SparSpec algorithm under a variety of simulated circumstances, and one actual test case from the JET tokamak, is analysed and appropriate conditions for the convergence of the memory-penalised solutions are derived. The tuning of the input parameters is discussed based on the results of our simulations. It is found that the implementation of SparSpec using such a memory with relaxation scheme is quite a complex procedure, and only when correctly optimized the results are superior, both in terms of the speed and the accuracy of the calculations, to those obtained with the SS-H2 and SS-V5ν0 versions of the SparSpec algorithm.
Study of diamond like carbon coatings formed by pulsed hydrocarbon ions irradiations over different substrate materials using plasma focus device
Authors: Niranjan Ram , Joycee J , Srivastava R , Patel N N , Joshi K D
Published: April 2021

Pulsed hydrocarbon ions produced in a plasma focus device were used to irradiate different substrate materials (Si, Ti, Mo and W) and to deposit thin films of carbon material over it. High energetic and high intensity pulsed hydrocarbon ions were produced when plasma focus device was filled with 0.5 mbar of acetylene gas and operated at 2 kJ. Effects of substrate materials properties, its thermal evolution under pulsed irradiation of energetic ions and plasma streams on the deposited films have been studied. Visible Raman spectroscopic measurements confirmed that deposited films were of diamond-like-carbon. Fraction of sp3 bonded carbon in films on different substrate materials (16%, 8.7%, 13% and 18.9% on Si, Ti, Mo and W respectively) was found to be correlated to substrate materials thermal properties i.e. high fraction of sp3 bonded carbon was observed over substrate materials having high thermal conductivity. Carbon atom concentrations were measured to be different (22.46 at. %, 22.7 at. %, 10.4 at. % and 32 at. % on Si, Ti, Mo and W respectively) over different substrates. Surface morphologies of DLC were also observed to be different for different substrates. On inserting graphite at anode tip, fraction of sp3 bonded carbon in DLC coating over Si substrate increased to 19.5%.
Electronic structure of cesium-based photocathode materials from density functional theory: performance of PBE, SCAN, and HSE06 functionals
Authors: Saßnick Holger-Dietrich , Cocchi Caterina
Published: April 2021

The development of novel materials for vacuum electron sources in particle accelerators is an active field of research that can greatly benefit from the results of ab initio calculations for the characterization of the electronic structure of target systems. As state-of-the-art many-body perturbation theory calculations are too expensive for large-scale material screening, density functional theory offers the best compromise between accuracy and computational feasibility. The quality of the obtained results, however, crucially depends on the choice of the exchange–correlation potential, v
xc. To address this essential point, we systematically analyze the performance of three popular approximations of v
xc [PBE, strongly constrained and appropriately normed (SCAN), and HSE06] on the structural and electronic properties of bulk Cs3Sb and Cs2Te as representative materials of Cs-based semiconductors employed in photocathode applications. Among the adopted approximations, PBE shows expectedly the largest discrepancies from the target: the unit cell volume is overestimated compared to the experimental value, while the band gap is severely underestimated. On the other hand, both SCAN and HSE06 perform remarkably well in reproducing both structural and electronic properties. Spin–orbit coupling, which mainly impacts the valence region of both materials inducing a band splitting and, consequently, a band-gap reduction of the order of 0.2 eV, is equally captured by all functionals. Our results indicate SCAN as the best trade-off between accuracy and computational costs, outperforming the considerably more expensive HSE06.
Development of a low-voltage driven non-resonant three-DOF eyeball-like piezoelectric actuator
Authors: Zheng Ke , Yang Ying , Qiu Jianmin , Ma Xinchi , Zhang Jiyang , Wang Yiping
Published: April 2021

In this work, a low-voltage driven non-resonant three degree-of-freedom (DOF) eyeball-like piezoelectric actuator is proposed. Elliptical motions on the driving feet are formed from the pushing and pulling actions of the flexible displacement amplification (FDA) mechanism in the piezoelectric actuator. There are three types of elliptical movements to drive the spherical rotor around three coordinate axes while driving the different groups of piezoelectric stacks. The principles of the three-DOF rotations are analysed by theoretical and simulation methods. Fabrication of a miniature piezoelectric prototype of 34mm × 34mm × 34mm is conducted. Under a driving voltage of 40

V

0
−
p

,

the maximum rotary velocities of the rotor around X, Y and Z axes reach to 62.5 r min−1, 65 r min−1 and 46 r min−1 at 1.5 kHz. High resolutions around X and Y axes up to 2.5

μ
rad

and 5

μ
rad

are obtained. The remarkable comprehensive performances enable much potential applications of this three-DOF eyeball-like piezoelectric actuator in precision pointing, attitude adjustment and bionic eye positioning systems.
A free-energy principle for representation learning
Authors: Gao Yansong , Chaudhari Pratik
Published: April 2021

This paper employs a formal connection of machine learning with thermodynamics to characterize the quality of learned representations for transfer learning. We discuss how information-theoretic functionals such as rate, distortion and classification loss of a model lie on a convex, so-called, equilibrium surface. We prescribe dynamical processes to traverse this surface under specific constraints; in particular we develop an iso-classification process that trades off rate and distortion to keep the classification loss unchanged. We demonstrate how this process can be used for transferring representations from a source task to a target task while keeping the classification loss constant. Experimental validation of the theoretical results is provided on image-classification datasets.
Australian Women Writing History during the Interwar and Second World War Years
Authors: Cooper Melinda
Published: April 2021

In the interwar and Second World War periods, women writers took the lead in the Australian literary scene in an unprecedented way, producing a number of significant novels, plays, and works of nonfiction that interrogated issues of colonialism, nationalism, gender relations, and Australia’s place in the world. Many of these works had period settings or were engaged in some way with Australia’s settler colonial past. While the historical writings of Australian women writers vary greatly in terms of literary style, genre, cultural value, political affiliation, and the degree to which they either contest or reify ideas of national progress, these works represent a substantial contribution to the reimagining of the nation’s past in the period from the late 1920s to the mid-1940s. Furthermore, many of the fictional works of these women writers traveled beyond national borders due to the new mobilities of publication and distribution available to Australian writers at the time. Two major case studies reveal the ways in which Australian women writers contributed to the writing of Australian history in both national and international contexts in the interwar and Second World War years: M. Barnard Eldershaw, the pseudonym for the literary collaboration between Marjorie Barnard (1897–1987) and Flora Eldershaw (1897–1956), and Eleanor Dark (1901–1985).
Experimental Designs in Business Research
Authors: Breitsohl Heiko
Published: April 2021

Conducting credible and trustworthy research to inform managerial decisions is arguably the primary goal of business and management research. Research design, particularly the various types of experimental designs available, are important building blocks for advancing toward this goal. Key criteria for evaluating research studies are internal validity (the ability to demonstrate causality), statistical conclusion validity (drawing correct conclusions from data), construct validity (the extent to which a study captures the phenomenon of interest), and external validity (the generalizability of results to other contexts). Perhaps most important, internal validity depends on the research design’s ability to establish that the hypothesized cause and outcome are correlated, that variation in them occurs in the correct temporal order, and that alternative explanations of that relationship can be ruled out.

Research designs vary greatly, especially in their internal validity. Generally, experiments offer the strongest causal inference, because the causal variables of interest are manipulated by the researchers, and because random assignment makes subjects comparable, such that the sources of variation in the variables of interest can be well identified. Natural experiments can exhibit similar internal validity to the extent that researchers are able to exploit exogenous events creating (quasi-)randomized interventions. When randomization is not available, quasi-experiments aim at approximating experiments by making subjects as comparable as possible based on the best available information. Finally, non-experiments, which are often the only option in business and management research, can still offer useful insights, particularly when changes in the variables of interest can be modeled by adopting longitudinal designs.
Queer People’s Communication With Families of Origin
Authors: Alvarez Cimmiaron , Scharp Kristina M.
Published: April 2021

Communicating with one’s family of origin requires considerable effort for queer people (e.g., LGBTQ+; queer is used as an encompassing term to include all gender and sexual identities that are not both cis and heterosexual). Queer people must decide if they want to disclose their gender and/or sexual identities, to whom they want to disclose, how they want to communicate, and anticipate the ways their family members may react. Immediate family members, such as parents and siblings, typically play an important role in queer people’s lives and are consequently some of the first people to whom queer people talk about their gender and/or sexual identities. Yet not all these disclosures are met with positive reactions from family members. Research suggests that queer people perceive their families’ reactions range from complete acceptance to total rejection. Thus, it is often the case that queer people must cope with multiple sources of stigma. From the family members’ perspective, parents and siblings also report having varied reactions to the queer person’s initial disclosure that require them to engage in sense-making. Thus, in addition to the communicative burden of queer people, their families may also have to share in the communicative work to communicate with people outside the family or (re)construct their family identity. All this communicative labor simultaneously reflects and constructs larger overarching ideologies surrounding gender and sexuality.
Relationship Conflict and Communication
Authors: Canary Daniel J.
Published: April 2021

Since the 1970s hundreds of scholars from several disciplines have devoted their energies to understanding interpersonal conflict communication. One cannot offer an inclusive essay on the topic, even if the space allowed is 10 times greater than given here.

One can, however, select salient aspects of the topic—those that appear often and implicate relational welfare. Toward that end, there are four parts to approaching the topic. First, a rationale for examining interpersonal conflict communication is presented. Emphasis on interpersonal conflict communication is confined to only a handful of reasons. Second, conceptualizations of interpersonal conflict are briefly represented and analyzed according to two dimensions that can help demarcate what scholars tend to study under the aegis of “conflict.” Third, a general pedagogical model of important considerations or “events” is given; each of the various components are elaborated, and each indicating what one should consider when involved in conflict. Fourth, future directions of research regarding the topic are explored.
Psychology of Crisis and Trauma
Authors: Enander Ann
Published: April 2021

The psychology of crisis and trauma is concerned with attitudes, reactions, and behaviors related to extreme events and conditions. Facing a crisis poses a number of challenges to the individual in terms of preparation, making sense of the situation, taking decisions, and coping with stress. Thus research on human reactions to crisis spans a broad range of theories and analytical frameworks. Traditionally there has been a strong focus on vulnerabilities and on the negative impacts of crises in terms of stress and traumatic responses. However, in the early 21st century research has increasingly moved toward investigating resilience factors and the ways in which people actually cope under extreme conditions.

Although the term crisis is often used as a general concept, the reality of critical events can vary widely, each posing particular challenges to those affected. This can be illustrated by examples from natural disasters, toxic incidents, and socially generated threats of violence and terror, where the psychological contexts of such events differ considerably.

While learning from the experiences of crisis events is important, research on human reactions does raise a number of practical and ethical issues of which the researcher needs to take heed.
Enduring Questions and Unsatisfactory Answers About Direct Democracy
Authors: Bowler Shaun , Donovan Todd
Published: April 2021

Direct democracy elections bring into sharp focus several enduring questions about the role of voters in elections. Questions of voter competence, majority rule, spending effects, and process concerns are all highlighted. Many of these questions form the basis of often very pointed debates within the literature. The study of direct democracy throws into sharp relief some of the most enduring questions relating to elections and electoral democracy. So far, however, the answers have not proved satisfying to many observers. In some cases, these debates have persisted despite an accumulation of empirical evidence that would seem to resolve the issues. Contrary to the claims of repeated criticisms, voters are capable of voting on ballot propositions in accord with their own interests and are supportive of the process as a means of making decisions. While direct democracy does have its flaws, the flaws identified by many critics are not really as damning as the critics would seem to believe. For whatever reason, however, the criticisms repeat.
Health Effects of Incarceration
Authors: Berk Justin , Ding Ann , Rich Josiah
Published: April 2021

Since 1976, incarcerated individuals in the United States have an established right to healthcare. This has created a national system charged with addressing the unique challenges of healthcare delivery in jails and prisons. As incarcerated populations are often excluded from large research studies, evidence-based practices must often be extrapolated from community data. There is a wide variation in care delivery across institutions nationwide. Challenges in correctional settings include a “dual loyalty” to patients’ health and facility security and the toxic effects of disciplinary practices including solitary confinement, violence, communicable disease control, an aging population, discharge planning for community reentry, and a high prevalence of substance use disorder and mental health disease. Although incarceration may offer a unique opportunity to address chronic health issues of a difficult-to-reach population, the net health effects in the United States seem to be mostly negative. Mass incarceration in the United States has led to significant health consequences at the individual, family, and community levels and has exacerbated health, socioeconomic, and racial disparities. As most incarcerated individuals return to the community, healthcare delivery during incarceration plays a substantial role in the health of communities at all levels.
Gangs, Drug Use, and Drug Selling in the United States
Authors: Sanders Bill
Published: April 2021

Gangs and drugs are two major criminological issues that come together in the United States. On the one hand, gang members use more drugs than non-gang youth, so much so that gang membership itself is an indicator that an individual will have a significant drug use profile. Compared with non-gang youth, gang members also begin to use drugs at earlier ages, use a greater variety of drugs, use them with greater frequency, and participate in other risk behaviors (e.g., violence, unsafe sexual behaviors) while intoxicated. Alcohol and marijuana feature prominently within the drug use repertoires of gang members, and the latter is considered normalized within gang cultures. Gang members also use other “hard” drugs, such as crystal methamphetamine, crack cocaine, and heroin, despite the fact that the use of such drugs is stigmatized among them. Gang membership is also characterized by polysubstance use—the simultaneous or sequential use of a variety of drugs, as well as nonmedical prescription drug misuse. As a result, gang members are at great risk of many negative social and health consequences related to drug use.

On the other hand, gang members sell drugs. A wealth of academic data contradicts the legal and public perceptions about this relationship. First, a commonly held view is that gangs control a majority of the sales of illegal drugs within any one area. However, this clashes with research specifically on gangs, which reveals that few members within any one gang sell drugs and that few gangs are specifically focused on selling drugs. Another area where academic research conflicts with widely held perceptions is the idea that drug selling is a lucrative endeavor for gang members. While the public and law enforcement agencies may believe gang members are making significant amounts of money selling drugs, research indicates that the majority of gang members who do sell drugs do not appear to earn significantly more money than they could earn working the same number of hours at a job paying minimum wage. Such findings further argue that such amounts hardly seem worth the risk given the large numbers of gang members killed or imprisoned in relation to selling drugs.
Cultural Bias in International Criminology
Authors: van Swaaningen René
Published: April 2021

To make some advances in international criminology, one needs to face that, historically, criminological knowledge has often been used to support colonial and authoritarian rule and acknowledge that international criminologists operate by and large in a culturally ill-informed vacuum in which a “universal” validity of Western theories is taken for granted. Starting from Edward Said’s famous critique of the “orientalism” of Western academics, an investigation is needed on how current cultural anthropological debates on cultural landscapes and cosmopolitan identities could help overcome this problem. The main scholarly debates in non-Western and counter-colonial criminology set a dialogue between perspectives elaborated by Global North scholars and viewpoints proposed by authors working in a variety of Global South regions. It constitutes, in this regard, a contribution to decolonize and globalize international criminology debates because it considers voices and visions all too frequently overlooked by the extant English-speaking literature. In addition, a nexus is set between current developments in this academic field and viewpoints put forth by critical criminology authors decades ago. It is argued that a culturally informed international criminology is not based on humanitarian do-gooderism or shame over a colonial past, rather, it is fundamental if criminologists are to understand the world around us and the “glocal” questions that confront the field.