bluuebunny/crossref_metadata_2025 huggingface dataset:
Evolution of magnetoresistance with temperature in the insulating van der Waals compound Ta2Pd3Te5
Authors: Tian Jianjun , Kang Chaoyang , She Limin , Song Yeheng , Zhang Weifeng
Published: April 2022

Ta2Pd3Te5 has been recently identified as a van der Waals topological crystalline insulator candidate, but its magnetotransport properties are not reported. Here, we study electrical transport properties of Ta2Pd3Te5 single crystals. Ta2Pd3Te5 shows an insulating behavior with a trend of saturation below 20 K. The activity energy determined from the fits to polaron hopping model is Ea ∼ 36.1 meV, close to the value of 42 meV determined from previous scanning tunneling microscopy measurement. The linear Hall resistivity with a negative slope suggests an n-type conductivity for bulk Ta2Pd3Te5. The magnetoresistance (MR) is positive at 2 K, and the dip-like feature at low magnetic fields is attributed to the weak antilocalization effect. On the other hand, a negative low-field MR develops in the temperature range between 5 and 30 K, which is identified as a fingerprint of the weak localization effect. Such a transition from weak antilocalization to weak localization with increasing temperature reveals that the spin–orbit interaction plays an important role in Ta2Pd3Te5. Our results reveal highly enriched physical properties in Ta2Pd3Te5 single crystals, and they can be exploited in future magnetoresistance device design.
A novel approach to quantify ventilation heterogeneity in occluded bronchial tree based on lung admittance
Authors: Soni Bharat , Nayak Ameeya Kumar , Wereley Steve
Published: April 2022

Obstructions in airways result in significant alterations in ventilation distribution and consequently reduce the ventilation to perfusion ratio, affecting gas exchange. This study presents a lumped parameter-based model to quantify the spatial ventilation distribution using constructal theory. An extension of the existing theory is made for the conductive bronchial tree and is represented in matrix frame incorporated with airway admittances. The proposed lung admittance model has a greater advantage over the existing methodologies based on lung impedance, as it can be applicable for both fully and partially blocked regions. We proved the well-posedness of the problem, and the generated matrix is highly sparse in nature. A modified block decomposition method is implemented for symmetric and asymmetric trees of various obstructions 0:20:100% to reduce the memory size. The asymmetry is considered in every left branch of the bronchial tree recursively, following the mathematical relations: Li, 2j=ΓLi, 2j+1 and Di, 2j=ΓDi, 2j+1, where L and D are the length, diameter of the jth branch at ith generation, respectively, for Γ∈0.9:0.01:1.0. It is observed that relative flow rate (Qi,jQi,jhealthy) decreases exponentially with the generation index. In tidal breathing, the regional ventilation pattern is found to vary spatially instead of spatio-temporally. The comparison of our result with the clinical data is found to be accurate when 40% or more obstruction is considered in the proximal region (observed in asthma). Moreover, this predicts an increment of lung impedance by 6%, which can be used for further improvement of clinical observations.
From film to ring: Quasi-circular inorganic lead halide perovskite grain induced growth of uniform lead silicate glass ring structure
Authors: Tong Guoqing , Song Wentao , Ono Luis K. , Qi Yabing
Published: April 2022

Polycrystalline properties of perovskites can induce the growth of different nanostructures, thanks to their facile fabrication. In this work, the CsPb2Br5 perovskite grains were used as templates to induce the growth of the ring-like structures on a SiO2/Si substrate. Owing to the oxidation of the volatile PbBr2 originated from the decomposition of CsPb2Br5, the grain boundaries of perovskites are prone to reaction with SiO2, which leads to the formation of Pb-silicate glass at high temperatures. The quasi-circular grain structure of CsPb2Br5 defines the final dimension of the Pb-silicate glass ring-like structures. X-ray photoelectron spectroscopy (XPS) measurement results reveal the formation and composition of the Pb-silicate glass ring-like structures converting from the halide perovskite film on the SiO2/Si substrate. Furthermore, these ring-like structures can extend to the field of display and pulsed-laser by combining existing techniques.
Recovering the second moment of the strain distribution from neutron Bragg edge data
Authors: Fogarty K. , Ametova E. , Burca G. , Korsunsky A. M. , Schmidt S. , Withers P. J. , Lionheart W. R. B.
Published: April 2022

Point by point strain scanning is often used to map the residual stress (strain) in engineering materials and components. However, the gauge volume and, hence, spatial resolution are limited by the beam defining apertures and can be anisotropic for very low and high diffraction (scattering) angles. Alternatively, wavelength resolved neutron transmission imaging has a potential to retrieve information tomographically about residual strain induced within materials through measurement in transmission of Bragg edges—crystallographic fingerprints whose locations and shapes depend on microstructure and strain distribution. In such a case, the spatial resolution is determined by the geometrical blurring of the measurement setup and the detector point spread function. Mathematically, reconstruction of the strain tensor field is described by the longitudinal ray transform; this transform has a non-trivial null-space, making direct inversion impossible. A combination of the longitudinal ray transform with physical constraints was used to reconstruct strain tensor fields in convex objects. To relax physical constraints and generalize reconstruction, a recently introduced concept of histogram tomography can be employed. Histogram tomography relies on our ability to resolve the distribution of strain in the beam direction, as we discuss in the paper. More specifically, Bragg edge strain tomography requires extraction of the second moment (variance about zero) of the strain distribution, which has not yet been demonstrated in practice. In this paper, we verify experimentally that the second moment can be reliably measured for a previously well characterized aluminum ring and plug sample. We compare experimental measurements against numerical calculation and further support our conclusions by rigorous uncertainty quantification of the estimated mean and variance of the strain distribution.
Angle dependent field-driven reorientation transitions in uniaxial antiferromagnet MnBi2Te4 single crystal
Authors: Cao Ning , Chen Xue , Mi Xinrun , Qiao Saisai , Zhang Liyu , Peng Kunling , He Mingquan , Wang Aifeng , Chai Yisheng , Zhou Xiaoyuan
Published: April 2022

MnBi2Te4, a two-dimensional magnetic topological insulator with a uniaxial antiferromagnetic structure, is an ideal platform to realize quantum anomalous Hall effects. However, the strength of magnetic interactions is not clear yet. We performed systematic studies on the magnetization and angle dependent magnetotransport on MnBi2Te4 single crystals. The results show that the direction of the magnetic field has significant effects on the critical field values and the magnetic structure of this compound, which lead to different magnetotransport behaviors. The field-driven reorientation transitions can be utilized to estimate the antiferromagnetic interlayer exchange interaction coupling Jc and uniaxial magnetic anisotropy D. The obtained Hamiltonian can well explain the experimental data by Monte Carlo simulations. Our comprehensive studies on the field-driven magnetic transition phenomenon in MnBi2Te4 provide a general approach for other topological systems with antiferromagnetism.
Machine-learning flow control with few sensor feedback and measurement noise
Authors: Castellanos R. , Cornejo Maceda G. Y. , de la Fuente I. , Noack B. R. , Ianiro A. , Discetti S.
Published: April 2022

A comparative assessment of machine-learning (ML) methods for active flow control is performed. The chosen benchmark problem is the drag reduction of a two-dimensional Kármán vortex street past a circular cylinder at a low Reynolds number (Re = 100). The flow is manipulated with two blowing/suction actuators on the upper and lower side of a cylinder. The feedback employs several velocity sensors. Two probe configurations are evaluated: 5 and 11 velocity probes located at different points around the cylinder and in the wake. The control laws are optimized with Deep Reinforcement Learning (DRL) and Linear Genetic Programming Control (LGPC). By interacting with the unsteady wake, both methods successfully stabilize the vortex alley and effectively reduce drag while using small mass flow rates for the actuation. DRL has shown higher robustness with respect to different initial conditions and to noise contamination of the sensor data; on the other hand, LGPC is able to identify compact and interpretable control laws, which only use a subset of sensors, thus allowing for the reduction of the system complexity with reasonably good results. Our study points at directions of future machine-learning control combining desirable features of different approaches.
A geometrical criterion for the dynamic snap-off event of a non-wetting droplet in a rectangular pore–throat microchannel
Authors: Li Zhang , Gu Zhaolin , Li Ran , Wang Chen , Chen Chungang , Yu Chunlei , Zhang Yigen , Shu Qinglin , Cao Weidong , Su Junwei
Published: April 2022

In porous media, non-wetting phase droplets snapping off in a constricted microchannel are one of the most common phenomena in two-phase flow processes. In this paper, the application range of the classic quasi-static criterion in rectangular cross section microchannels is obtained. For three different droplet breakup phenomena—total breakup, partial breakup, and non-breakup—observed in experiments when a non-wetting phase droplet passes through a microchannel constriction, the breakup is caused by the droplet neck snapping off in a channel constriction. A critical criterion for the dynamic snap-off event in a two-phase flow is proposed considering the effect of viscous dissipation by mechanical analysis, energy dissipation analysis, and many microfluidic experiments. When the droplet front flows out of the constriction, snap-off will occur if the surface energy release exceeds the required energy for viscous dissipation and kinetic energy conversion. The unique partial breakup phenomenon is affected by droplet surfactant distribution and the acceleration effect in the constriction center. This partial breakup phenomenon in experiments is an essential evidence for the non-uniform distribution of surfactants in the droplet surface. The results of this study contribute to understanding pore-scale mass transfer and flow pattern changes within porous media.
Aging or DEAD: Origin of the non-monotonic response to weak self-propulsion in active glasses
Authors: Klongvessa Natsuda , Ybert Christophe , Cottin-Bizonne Cécile , Kawasaki Takeshi , Leocmach Mathieu
Published: April 2022

Among amorphous states, glass is defined by relaxation times longer than the observation time. This nonergodic nature makes the understanding of glassy systems an involved topic, with complex aging effects or responses to further out-of-equilibrium external drivings. In this respect, active glasses made of self-propelled particles have recently emerged as a stimulating systems, which broadens and challenges our current understanding of glasses by considering novel internal out-of-equilibrium degrees of freedom. In previous experimental studies we have shown that in the ergodicity broken phase, the dynamics of dense passive particles first slows down as particles are made slightly active, before speeding up at larger activity. Here, we show that this nonmonotonic behavior also emerges in simulations of soft active Brownian particles and explore its cause. We refute that the deadlock by emergence of active directionality model we proposed earlier describes our data. However, we demonstrate that the nonmonotonic response is due to activity enhanced aging and thus confirm the link with ergodicity breaking. Beyond self-propelled systems, our results suggest that aging in active glasses is not fully understood.
Development of subgrid-scale model for LES of Burgers turbulence with large filter size
Authors: Tabe Jamaat A. Golsa , Hattori B. Yuji
Published: April 2022

A neural network (NN) with one hidden layer is implemented to establish a relationship between the resolved-scale flow field and the subgrid-scale (SGS) stress for large eddy simulation (LES) of the Burgers equation. Five sets of input are considered for the neural network by combining the velocity gradient and the filter size. The training datasets are obtained by filtering the direct numerical simulation (DNS) results of the Burgers equation with random forcing function. The number of modes is sufficiently large (N = 65 536) to resolve extremely small scales of motion. In the a priori test, a correlation coefficient over 0.93 is achieved for the SGS stress between the NN models and the filtered DNS data. The results of the a posteriori test reveal that the obtained solutions are stable for all NN models without applying any stabilization techniques. However, not all NN models have a reasonable performance when embedded in the LES code. The applicability of the NN models to the Burgers equation with higher and lower viscosity is also investigated, and it is indicated that the most reliable NN models obtained in this paper can be applied to a set of parameters which are different from those used in training. The results of the SGS models constructed using the neural network are also compared with the existing models, and it is shown that the best obtained NN models outperform the Smagorinsky model and the gradient model, and are comparable to the dynamic Smagorinsky model. However, the NN models have an advantage over the dynamic Smagorinsky model in numerical cost.
Organic photoredox catalysts for CO2 reduction: Driving discovery with genetic algorithms
Authors: Kron Kareesa J. , Rodriguez-Katakura Andres , Regu Pranesh , Reed Maria N. , Elhessen Rachelle , Mallikarjun Sharada Shaama
Published: April 2022

This work implements a genetic algorithm (GA) to discover organic catalysts for photoredox CO2 reduction that are both highly active and resistant to degradation. The lowest unoccupied molecular orbital energy of the ground state catalyst is chosen as the activity descriptor and the average Mulliken charge on all ring carbons is chosen as the descriptor for resistance to degradation via carboxylation (both obtained using density functional theory) to construct the fitness function of the GA. We combine the results of multiple GA runs, each based on different relative weighting of the two descriptors, and rigorously assess GA performance by calculating electron transfer barriers to CO2 reduction. A large majority of GA predictions exhibit improved performance relative to experimentally studied o-, m-, and p-terphenyl catalysts. Based on stringent cutoffs imposed on the average charge, barrier to electron transfer to CO2, and excitation energy, we recommend 25 catalysts for further experimental investigation of viability toward photoredox CO2 reduction.
Quantum phonon transport through channels and molecules—A Perspective
Authors: Gotsmann Bernd , Gemma Andrea , Segal Dvira
Published: April 2022

Phonon transport is a dominant mechanism of thermal conduction in solids that has been studied for decades. A good understanding of many transport regimes in micro- and nanostructures has been established, including ballistic and diffusive transport, mode softening, or band structure engineering in phononic crystals. However, the limit of quantized transport and the engineering of single transport channels is much less explored. In this Perspective, we discuss concepts and theoretical and experimental progress in the field of quantized phonon transport in channels, such as molecular systems. We particularly highlight open questions and research opportunities that should be within experimental reach. Challenges in experimental sensitivity and control hinder fast experimental progress. Recently, however, heat transport measurements through quantum channels and single molecules have become available at room temperature using break junction techniques. These techniques are well established in the molecular electronics community and have recently been expanded to the measurement of heat transport on the single-molecule level. Given the new experimental capabilities, it is now inviting to address the rather unexplored area of molecular phonon-engineering. Several interesting theoretical predictions concern the realization of the phonon quantum interference effect, suppression of phonon current via the introduction of side groups to molecules, and the construction of a phonon diode device based on molecular anharmonicity and asymmetry. This Perspective should serve the experimental and theory community by listing key challenges, thus a roadmap for making progress in the field of quantized phonon transport.
Perspective on phase-controlled currents in semiconductors driven by structured light
Authors: Sederberg Shawn , Corkum Paul B.
Published: April 2022

Controlling electrons with ever-greater precision is central to both classical and quantum electronics. Since the invention of the laser, virtually every property of coherent light has been tamed, making it one of the most precise tools available to science, technology, and medicine. Coherent control involves the transduction of an exquisitely defined property of light to an electronic system, imparting coherence to an attribute of its constituent electrons. Early developments in coherent control utilized Gaussian laser beams and spatially averaged measurements. The spatial structure and orbital angular momentum of laser light provide additional degrees of freedom for steering electronic and quasiparticle excitations in condensed matter systems. In this Perspective, we first introduce the concept of coherent control in semiconductors. We then proceed to discuss the application of structured light beams to coherent control and the requirement for spatially resolved current detection. Subsequently, we present an overview of recent experiments that were performed using cylindrical vector beams and laser beams with structured phase fronts. Finally, we provide an outlook on the horizons that have emerged with these developments and future directions of interest.
Molecular orbital projectors in non-empirical jmDFT recover exact conditions in transition-metal chemistry
Authors: Bajaj Akash , Duan Chenru , Nandy Aditya , Taylor Michael G. , Kulik Heather J.
Published: April 2022

Low-cost, non-empirical corrections to semi-local density functional theory are essential for accurately modeling transition-metal chemistry. Here, we demonstrate the judiciously modified density functional theory (jmDFT) approach with non-empirical U and J parameters obtained directly from frontier orbital energetics on a series of transition-metal complexes. We curate a set of nine representative Ti(III) and V(IV) d1 transition-metal complexes and evaluate their flat-plane errors along the fractional spin and charge lines. We demonstrate that while jmDFT improves upon both DFT+U and semi-local DFT with the standard atomic orbital projectors (AOPs), it does so inefficiently. We rationalize these inefficiencies by quantifying hybridization in the relevant frontier orbitals. To overcome these limitations, we introduce a procedure for computing a molecular orbital projector (MOP) basis for use with jmDFT. We demonstrate this single set of d1 MOPs to be suitable for nearly eliminating all energetic delocalization and static correlation errors. In all cases, MOP jmDFT outperforms AOP jmDFT, and it eliminates most flat-plane errors at non-empirical values. Unlike DFT+U or hybrid functionals, jmDFT nearly eliminates energetic delocalization and static correlation errors within a non-empirical framework.
MicroRNA-29a attenuates CD8 T cell exhaustion and induces memory-like CD8 T cells during chronic infection
Authors: Stelekati Erietta , Cai Zhangying , Manne Sasikanth , Chen Zeyu , Beltra Jean-Christophe , Buchness Lance Alec , Leng Xuebing , Ristin Svetlana , Nzingha Kito , Ekshyyan Viktoriya , Niavi Christina , Abdel-Hakeem Mohamed S. , Ali Mohammed-Alkhatim , Drury Sydney , Lau Chi Wai , Gao Zhen , Ban Yuguang , Zhou Simon K. , Ansel K. Mark , Kurachi Makoto , Jordan Martha S. , Villarino Alejandro V. , Ngiow Shin Foong , Wherry E. John
Published: April 2022

Significance

CD8 T cell exhaustion is a key underlying factor limiting immunity in chronic infections and cancer. Persistent antigen exposure antagonizes formation of functional memory CD8 T cells that provide long-term protection and, instead, drives the development of exhausted CD8 T cells (T
EX
). Improving T
EX
persistence and function is a major goal for reinvigorating immune responses against chronic infections and tumors. Here, we identify miR-29a as a molecule that attenuates exhaustion and enhances persistence and function of T
EX
. Enforced expression of miR-29a alters T
EX
transcriptome, resulting in robust changes in molecular pathways governed by fundamental transcription factors and epigenetic modulators. Thus, enforced miR-29a expression enhances T
EX
responses, attenuates exhaustion, and represents a target for improving the outcome of immunotherapy.
Climate transition at the Eocene–Oligocene influenced by bathymetric changes to the Atlantic–Arctic oceanic gateways
Authors: Straume Eivind O. , Nummelin Aleksi , Gaina Carmen , Nisancioglu Kerim H.
Published: April 2022

Significance

The results show that dynamic variations in the Earth’s interior could have played a key role in the Eocene–Oligocene climatic transition (∼33.9 Ma) and the inception of glaciations. Pulsations in the Iceland mantle plume modified the bathymetry of the Greenland–Scotland Ridge, which affected deep water formation in the North Atlantic. Our model simulations show that the changes in the Atlantic–Arctic oceanic gateways cooled the Southern Hemisphere, and later the Northern Hemisphere, paving the way for the growth of major land-based ice sheets. This supplements the current view that decreasing atmospheric CO
2
concentrations and/or changes to the Southern Ocean gateways or the Tethys Seaway dominated climate changes and the inception of glaciations at the time.
Stabilizing microbial communities by looped mass transfer
Authors: Li Shuang , Abdulkadir Nafi'u , Schattenberg Florian , Nunes da Rocha Ulisses , Grimm Volker , Müller Susann , Liu Zishu
Published: April 2022

Significance

The population ecology of microbial communities is still poorly understood and their notorious instability makes them impossible to control. Much of the instability is caused by the stochastic assembly of microorganisms, especially in highly diverse microbiomes where structural and hence functional changes occur rapidly due to the short generation time of their members. Usually, to maintain organismic proportions in communities, their niches are deterministically reinforced, but stochasticity strongly counteracts this. Based on metacommunity theory, a looped mass transfer was developed that uses the rescue effect to stabilize communities. This study fills a long-standing gap and enables continuous and proportionally equal growth of community members using an unprecedented operational design that addresses an acute need in the healthcare and biotechnology industries.
Three world wars: Fiscal–monetary consequences
Authors: Hall George J. , Sargent Thomas J.
Published: April 2022

Significance

We detect common forces that impinged on US monetary and fiscal policies during two 20th century world wars and now during the War on COVID-19 and then compare government and market responses to these forces. The US government had to finance large wartime surges in its expenditures by taxing, borrowing, or printing money. We document and interpret consequences of the choices that the government made in these three world wars.
Religiosity, abortion stigma and the mediating effect of gender attitudes. A study in the Chilean population (Religiosidad, estigma del aborto, y el efecto mediador de las actitudes de género. Un estudio en población chilena)
Authors: Pérez-Sánchez Beatriz , Concha-Salgado Andrés , Aburto-González Valeria , Mandiola-Sandoval Catalina , Muñoz-Henríquez Christopher , Cerda-Muñoz Denisse
Published: April 2022

Abortion Stigma (AS) is a negative attribute ascribed to women who terminate a pregnancy that marks her as inferior to the ideals of femininity. Based on traditional normative gender codes, religious groups are identified in the literature as the most relevant source of AS. To analyse the influence of religiosity on AS and the mediating effect of stereotyped gender attitudes, we carried out a multivariate causal quantitative study. With a community sample of 360 Chileans, we used structural equation modelling to determine that religiosity influences AS directly and indirectly through stereotyped gender attitudes. This model showed adequate fit indices and explained 69.2% of the variance. We tested a second structural equation model with a control variable, and we discuss these findings’ implications for Chilean society, where religion occupies a significant place in power and decision-making centres. We propose gender equity education as a strategy to reduce AS.
Cytosolic Ca2+-dependent Ca2+ release activity primarily determines the ER Ca2+ level in cells expressing the CPVT-linked mutant RYR2
Authors: Kurebayashi Nagomi , Murayama Takashi , Ota Ryosaku , Suzuki Junji , Kanemaru Kazunori , Kobayashi Takuya , Ohno Seiko , Horie Minoru , Iino Masamitsu , Yamashita Fumiyoshi , Sakurai Takashi
Published: April 2022

Type 2 ryanodine receptor (RYR2) is a cardiac Ca2+ release channel in the ER. Mutations in RYR2 are linked to catecholaminergic polymorphic ventricular tachycardia (CPVT). CPVT is associated with enhanced spontaneous Ca2+ release, which tends to occur when [Ca2+]ER reaches a threshold. Mutations lower the threshold [Ca2+]ER by increasing luminal Ca2+ sensitivity or enhancing cytosolic [Ca2+] ([Ca2+]cyt)-dependent activity. Here, to establish the mechanism relating the change in [Ca2+]cyt-dependent activity of RYR2 and the threshold [Ca2+]ER, we carried out cell-based experiments and in silico simulations. We expressed WT and CPVT-linked mutant RYR2s in HEK293 cells and measured [Ca2+]cyt and [Ca2+]ER using fluorescent Ca2+ indicators. CPVT RYR2 cells showed higher oscillation frequency and lower threshold [Ca2+]ER than WT cells. The [Ca2+]cyt-dependent activity at resting [Ca2+]cyt, Arest, was greater in CPVT mutants than in WT, and we found an inverse correlation between threshold [Ca2+]ER and Arest. In addition, lowering RYR2 expression increased the threshold [Ca2+]ER and a product of Arest, and the relative expression level for each mutant correlated with threshold [Ca2+]ER, suggesting that the threshold [Ca2+]ER depends on the net Ca2+ release rate via RYR2. Modeling reproduced Ca2+ oscillations with [Ca2+]cyt and [Ca2+]ER changes in WT and CPVT cells. Interestingly, the [Ca2+]cyt-dependent activity of specific mutations correlated with the age of disease onset in patients carrying them. Our data suggest that the reduction in threshold [Ca2+]ER for spontaneous Ca2+ release by CPVT mutation is explained by enhanced [Ca2+]cyt-dependent activity without requiring modulation of the [Ca2+]ER sensitivity of RYR2.
Quick counting of probability distributions for the sum of multi-sided dice: a physical and didactic approach
Authors: Sánchez S Sergio , Cortés P Ernesto , Moreno O Victor I , Pacheco B Daniel , Aguilar A Francisco
Published: April 2022

There are many physical systems (with randomness) where the performance of the probability distribution is of great importance [for example the so-called radioactive dice (Murray and Hart 2012 Phys. Educ.
47 197–201)]. A relevant situation is when the value (positive integers) of the upper faces is added when rolling fair dice (unbiased), that is, balanced, regular or unshaven. It has been widely studied in the basic literature for one, two and a maximum of four dice. However, a generalization using these methods for many dice is too cumbersome to carry out. In this paper we explore a method that uses the moment generating function, already studied in Singh et al (2011 UNLV Gaming Res. Rev. J.), for five six-sided fair dice with positive integer values. We carry out the generalization of this method to study the performance of the probability distribution and make a quick counting without complications for the sum of n fair dice with s sides (s ⩾ 6), and real values. We also study the invariance of the distribution when we set the number of sides, that is, for s-fix. Therefore, we study the distributions for the outgoing total sum (random variable) of roll generalized dice, for combinations of n multi-sided dice.
Photoluminescence intensity of Cu-doped ZnO modulated via defect occupancy by applying electric bias
Authors: Ho Lok-Ping , Younas Muhammad , Borgersen Jon , Khan Rao Tahir Ali , Rezvani Seyed Javad , Pollastri Simone , Akhtar Muhammad Javed , Nadeem Muhammad , Huang Dong , Shi Ying-Li , Kuznetsov Andrej , Ling Francis Chi-Chung
Published: April 2022

Discovering multifunctional materials is of paramount importance for advancing the science and technology. Herein, we report on an optical phenomenon modulated by an electrical process that happened at the metal–ZnO:Cu junction, for which the light emission intensity from the photoluminescence is tuned reversibly by applying electric bias to the junction. Importantly, these observations were correlated with the x-ray absorption measurements, detecting prominent flips in Cu+/Cu2+ oxidation state occupations in ZnO:Cu film as a function of the resistive switching. Moreover, further analysis of the x-ray absorption data revealed an additional prominent correlation—the signals interpreted as the Zn–O bond fingerprints also exhibited the modulations. By considering the whole set of data, we propose a scenario explaining the modulation phenomena.
Frustration, strain and phase co-existence in the mixed valent hexagonal iridate Ba3NaIr2O9
Authors: Garg Charu , Cervellino Antonio , Nair Sunil
Published: April 2022

Using detailed synchrotron diffraction, magnetization, thermodynamic and transport measurements, we investigate the relationship between the mixed valence of Ir, lattice strain and the resultant structural and magnetic ground states in the geometrically frustrated triple perovskite iridate Ba3NaIr2O9. We observe a complex interplay between lattice strain and structural phase co-existence, which is typically not observed in this family of compounds. The low temperature magnetic ground state is characterized by the absence of long-range magnetic order, and points towards the condensation of a cluster glass state from an extended regime of short range magnetic correlations.
Phase-controlled synthesis of SnS2 and SnS flakes and photodetection properties
Authors: Luo Jiaqi , Song Xiaohui , Lu Yingying , Hu Yanjie , Lv Xiaojing , Li Lin , Li Xueping , Deng Jianping , Yan Yong , Jiang Yurong , Xia Congxin
Published: April 2022

Two-dimensional (2D) layered tin sulfide compounds including SnS2 and SnS have attracted increasing attention due to their great potential application in the fields of optoelectronics and energy storage. However, device development has been delayed by the lack of capabilities to synthesize large-scale and high-quality 2D tin sulfide. Here, a phase-controlled synthesis of SnS2 and SnS flakes with lateral size over 100 μm was successfully realized via a facile chemical vapor deposition method. The lateral size of flakes and phase transformation of SnS2 to SnS can be tuned via changing the synthesis temperature. Compared to the formation of the SnS2 phase at relative low temperature (<750 °C), the SnS phase is favorable at higher temperature. The phototransistor based on the as-prepared SnS2 and SnS exhibits excellent photoresponse to 405 nm laser, including a high responsivity (1.7 × 106 mA W−1), fast response rates (rise/decay time of 13/51 ms), an outstanding external quantum efficiency (5.3 × 105%), and a remarkable detectivity (6.24 × 1012 Jones) for SnS2-based phototransistor, and these values are superior to the most reported SnS2 based photodetectors. Although the responsivity (3390 mA W−1) and detectivity (1.1 × 1010 Jones) of SnS-based device is lower than that of the SnS2 phototransistor, it has a faster rise/decay time of 3.10/1.59 ms. This work provides a means of tuning the size and phase of 2D layered tin sulfide, and promotes the application of SnS2 in high-performance optoelectronic devices.
Quantum simulation of fermionic systems using hybrid digital–analog quantum computing approach
Authors: Guseynov N M , Pogosov W V
Published: April 2022

We consider a hybrid digital–analog quantum computing approach, which allows implementing any quantum algorithm without standard two-qubit gates. This approach is based on the always-on interaction between qubits, which can provide an alternative to such gates. We show how digital–analog approach can be applied to simulate the dynamics of fermionic systems, in particular, the Fermi–Hubbard model, using fermionic SWAP network and refocusing technique. We concentrate on the effects of connectivity topology, the spread of interaction constants as well as on errors of entangling operations. We find that an optimal connectivity topology of qubits for the digital–analog simulation of fermionic systems of arbitrary dimensionality is a chain for spinless fermions and a ladder for spin 1/2 particles. Such a simple connectivity topology makes digital–analog approach attractive for the simulation of quantum materials and molecules.
A study on the real-time compensation system based on Abbe principle for range accuracy of submicron measuring instrument
Authors: Tianci Feng , Chengjun Cui , Shan Wang , Dengfeng Dong , Weihu Zhou , Jianli Li
Published: April 2022

Range accuracy is an important parameter to evaluate the performance of laser tracker. However, the different field-testing methods of laser tracker influenced the range accuracy. In this paper, we propose a universal scheme for correcting range accuracy of laser tracker based on Abbe principle. The reasons for the Abbe error have been analyzed and the theoretical calculation and simulation verification have been done. Finally, we built Abbe error compensation system by using the autocollimator to compensate the distance accuracy error of home-made laser tracker. The experimental results show that the ranging accuracy after compensation can be improved from 1.828 ppm to 0.496 ppm. The method proposed in this paper is also applicable to the range accuracy calibration of other submicron measuring instruments.
Volumetric particle tracking velocimetry with improved algorithms using a two-view shadowgraph system
Authors: Wu Y , Zhao C Y , Wang Q
Published: April 2022

Determining the time-resolved three-dimensional (3D) three-component (3C) velocity is essential for complex turbulent flow measurements. The current study is an extension of a recently developed temporal-spatial three-dimensional particle tracking velocimetry (TS 3D-PTV) technique established for two-view imaging systems. Two improvements have been embedded in TS 3D-PTV algorithm to improve the accuracy at high particle image densities (up to 0.03 ppp). One is using the neighboring particle information to correct the predicted positions and select the temporal particles with higher probability; the other is to iteratively optimize the 2D particle positions during the tracking process using the temporal and image information. The synthetic particle tests indicate that the correctness can be increased by 4.7%–5.8%, to reach a value about 92% with the improved algorithm around 0.03 ppp. The comparative results also indicate that using an advanced particle identification algorithm can improve the correctness over 20%. Two experiments, including a buoyancy jet in water and a transient droplet splashing process, have been conducted with a two-view shadowgraph imaging system. Different tracking algorithms have been conducted to determine the 3D trajectories of seeding particles or secondary droplets comparatively. The new algorithm has shown the best performance with much longer and more reliable trajectories, which indicates the tracking interruption caused by particle overlapping is reduced. The newly developed algorithms have further improved the performance under high seeding density conditions, which makes the two-view shadowgraph 3D PTV system adaptable to more experimental conditions.
Investigation of textured sensing skin for monitoring fatigue cracks on fillet welds
Authors: Liu Han , Laflamme Simon , Li Jian , Bennett Caroline , Collins William N , Eisenmann David J , Downey Austin R J , Ziehl Paul , Jo Hongki
Published: April 2022

Load-induced fatigue cracking in welds is a critical safety concern for steel transportation infrastructure, and the automation of their detection using commercial sensing technologies remains challenging due to the randomness in crack initiation and propagation. The authors have previously proposed a corrugated soft elastomeric capacitor (cSEC), which is a flexible and ultra-compliant thin-film strain gauge that transduces strain into a measurable change in capacitance. The cSEC technology has been successfully demonstrated for measuring bending strain as well as angular rotation in a folded configuration. This study builds on prior discoveries to characterize the sensor’s capability at monitoring fatigue cracks in corner welds, for which the sensor needs to be installed in a folded configuration. A crack monitoring algorithm is developed to fuse the cSEC data into actionable information. Experimental work is conducted on an orthogonal welded connection, mimicking a plate-to-web joint in steel bridges, with cSECs folded over the fillet welds. The sensor’s electromechanical behavior is characterized, and results confirm that the cSEC is capable of fatigue crack detection and quantification. In particular, results show that the cSEC can detect a minimum crack length of 0.48 mm and that its overall sensing performance, including signal linearity, resolution, and accuracy, is adequate under no damage, yet decreases with increasing crack size, likely attributable to the simplification of the electromechanical model and higher noise produced by the loading equipment under smaller applied displacement.
MoS2/MXene pillared nanocomposite for ultrafast photonics applications
Authors: Guo Lihao , Lei Jingjing , Zhang Yongfeng , Duan Xinghao , Wang Xiaoli , Zhang Zihao , Wei Zhiyi , Li Lan , Guo Qiyun , Liu Xiaoyao , Ning Ruizhi , Wang Junli , Hu Wenwen , Wu Weiwei
Published: April 2022

In this work, we used nanocomposite saturable absorbers (SAs) in order to precisely design and modulate the process of compositing the light absorption by band gap engineering. Due to the higher absorption intensity of our MoS2/MXene nanocomposite, we have successfully shortened the pulse duration (1.2 μs) of SA with enhancing saturable absorption intensity (7.22 MW cm−2), and the ultra-fast fiber laser based on this nanocomposite SA has shown wider Q-switching stable range in the case of high pump power. This strategy can efficiently improve the performance of SA and shows the potential application prospect of nanocomposites in nonlinear optics.
Photocatalytic hydrogen evolution based on carbon nitride and organic semiconductors
Authors: Zhang Hantang , Liu Jie , Jiang Lang
Published: April 2022

Photocatalytic hydrogen evolution (PHE) presents a promising way to solve the global energy crisis. Metal-free carbon nitride (CN) and organic semiconductors photocatalysts have drawn intense interests due to their fascinating properties such as tunable molecular structure, electronic states, strong visible-light absorption, low-cost etc. In this paper, the recent progresses of photocatalytic hydrogen production based on organic photocatalysts, including CN, linear polymers, conjugated porous polymers and small molecules, are reviewed, with emphasis on the various strategies to improve PHE efficiency. Finally, the possible future research trends in the organic photocatalysts are prospected.
Millisecond speed deep learning based proton dose calculation with Monte Carlo accuracy
Authors: Pastor-Serrano Oscar , Perkó Zoltán
Published: April 2022

Objective. Next generation online and real-time adaptive radiotherapy workflows require precise particle transport simulations in sub-second times, which is unfeasible with current analytical pencil beam algorithms (PBA) or Monte Carlo (MC) methods. We present a deep learning based millisecond speed dose calculation algorithm (DoTA) accurately predicting the dose deposited by mono-energetic proton pencil beams for arbitrary energies and patient geometries. Approach. Given the forward-scattering nature of protons, we frame 3D particle transport as modeling a sequence of 2D geometries in the beam’s eye view. DoTA combines convolutional neural networks extracting spatial features (e.g. tissue and density contrasts) with a transformer self-attention backbone that routes information between the sequence of geometry slices and a vector representing the beam’s energy, and is trained to predict low noise MC simulations of proton beamlets using 80 000 different head and neck, lung, and prostate geometries. Main results. Predicting beamlet doses in 5 ± 4.9 ms with a very high gamma pass rate of 99.37 ± 1.17% (1%, 3 mm) compared to the ground truth MC calculations, DoTA significantly improves upon analytical pencil beam algorithms both in precision and speed. Offering MC accuracy 100 times faster than PBAs for pencil beams, our model calculates full treatment plan doses in 10–15 s depending on the number of beamlets (800–2200 in our plans), achieving a 99.70 ± 0.14% (2%, 2 mm) gamma pass rate across 9 test patients. Significance. Outperforming all previous analytical pencil beam and deep learning based approaches, DoTA represents a new state of the art in data-driven dose calculation and can directly compete with the speed of even commercial GPU MC approaches. Providing the sub-second speed required for adaptive treatments, straightforward implementations could offer similar benefits to other steps of the radiotherapy workflow or other modalities such as helium or carbon treatments.
Low energy non-volatile look-up table using 2 bit ReRAM for field programmable gate array
Authors: Chee Hock Leong , Kumar T Nandha , Almurib Haider A F
Published: April 2022

A low energy non-volatile look-up table (NV-LUT) consisting of 2 bit resistive random-access memories (2 bit ReRAMs) for field-programmable gate arrays (FPGAs) is investigated in this paper. The multi-bit (MB) LUT configuration reduces the number of array cells by half compared to single-bit (SB) ReRAM-based arrays. A comparison of WRITE and READ delay time, energy consumption, and energy delay product (EDP) is carried out between the SB-NVLUT and MB-NVLUT. Different 2, 4, 6, and 8-input LUT configurations were compared. For WRITE 0 and 1 conditions, the MB-NVLUT is 2× faster than the SB-NVLUT and has an average of 1.22× and 2× lower energy consumption and 2.46× and 4.6× lower EDP respectively. For 01 → 10 switching, the MB-NVLUT write delay remains 2× quicker while having 1.03× lower energy consumption and 2.05× lower EDP. The MB-NVLUT is 9.2× lower in write delay, 128× lower in energy consumption, and 153× lower in EDP compared to the SB-NVLUT in 10 → 01 switching. SB-NVLUTs and MB-NVLUTs are then evaluated on Virtex 4 and Virtex 5 FPGA benchmark circuits with the average EDP for SB-NVLUTs greater than that of the MB-NVLUTs and both NVLUTs demonstrating performance matching conventional static RAM LUTs. A LUT controller circuit specifically designed for MB-NVLUT arrays is proposed. The reduction in the MB-NVLUT array cells leads to reduction in components in the controller circuit and improved performances over SB-NVLUTs.
Numerical investigation of the mechanical properties of 2D and 3D auxetic structures
Authors: Orhan Süleyman Nazif , Erden Şeydanur
Published: April 2022

Auxetic materials and structures have a negative Poisson’s ratio and it is this unique property that differentiates them from traditional materials. In recent years, three-dimensional (3D) auxetic structures have attracted considerable interest with the emergence of advanced manufacturing technologies. Many studies have been carried out to determine the mechanical properties of the existing 3D structures or improve and develop new ones, and extensive research is ongoing. This paper presents a comparative numerical study of two-dimensional (2D) and 3D geometries of four different auxetic structures, namely: elliptic holes, lozenge grids, re-entrant and arrowhead. Among these structures, elliptic holes and lozenge grids are designed and studied in 3D for the first time in this study. The structures are analysed under axial tension and the Poisson’s ratio, Young’s modulus and stiffness values are obtained from linear finite element model analysis. In addition, the unit cells of the 3D structures are examined. The findings showed that the elliptical holes structure exhibits a higher negative Poisson’s ratio than other auxetics and the 3D re-entrant and 2D arrowhead structures outperform the other auxetics with respect to the Young’s modulus and stiffness values.
Research on the vibration transmission characteristics of quasi-periodic impedance layered structure constructed by magnetorheological fluid
Authors: Si Qianqian , Wang Lei , Sun ZeBang
Published: April 2022

In this work, the theoretical and experimental study on vibration transmission in quasi-periodic impedance layered structures built by magnetorheological (MR) fluid is conducted. Based on the MR effect of MR fluid, the quasi-periodic layered structures formed by low and high impedance layers following Fibonacci, Thue–Morse and multiperiodic sequences are constructed, respectively. These different quasi-periodic patterns can be flexibly obtained by controlling the arrangement style and magnetic field strength of electromagnets outside the MR fluid. The vibration transfer model is established based on the transfer matrix method and the trends of vibration level difference with different parameters are analyzed. Furthermore, experiments are performed to estimate the vibration transmissivity of the proposed structures. It indicates that the developed quasi-periodic impedance layered structures can exhibit greater damping effect on vibrations by appropriately increasing the magnetic field strength and thickness ratio of low to high impedance layers. Moreover, there exist quasi-periodic impedance patterns whose attenuation effect on vibration is better than that of periodic pattern in the frequency range studied in this paper (20–200 Hz). This means that the introducing of the particular quasi-periodicity increases the transmission loss of vibrations in a certain frequency range. This investigation is conducive to further expand the application of MR materials and quasi-periodic structures in the field of vibration control.