bluuebunny/crossref_metadata_2025 huggingface dataset:
Statistics for an object actively driven by spontaneous symmetry breaking into reversible directions
Authors: Menzel Andreas M.
Published: July 2022

Propulsion of otherwise passive objects is achieved by mechanisms of active driving. We concentrate on cases in which the direction of active drive is subject to spontaneous symmetry breaking. In our case, this direction will be maintained until a large enough impulse by an additional stochastic force reverses it. Examples may be provided by self-propelled droplets, gliding bacteria stochastically reversing their propulsion direction, or nonpolar vibrated hoppers. The magnitude of active forcing is regarded as constant, and we include the effect of inertial contributions. Interestingly, this situation can formally be mapped to stochastic motion under (dry, solid) Coulomb friction, however, with a negative friction parameter. Diffusion coefficients are calculated by formal mapping to the situation of a quantum-mechanical harmonic oscillator exposed to an additional repulsive delta-potential. Results comprise a ditched or double-peaked velocity distribution and spatial statistics showing outward propagating maxima when starting from initially concentrated arrangements.
High-frequency permeability of porous media with thin constrictions. II. Porous media containing thin holed membranes
Authors: Langlois V. , Nguyen C. T. , Perrot C.
Published: July 2022

In this series of publications, the high-frequency behavior of the dynamic permeability of porous media with thin constriction is investigated. In Paper I, the classical theory of Johnson et al. [J. Fluid Mech. 176, 379 (1987)] for soft-curved pore geometries is recalled. For wedge-shaped pore geometries, numerical computations (by the finite element method) and analysis by Cortis et al. [Phy. Fluids 15, 1766 (2003)] are revisited and confirmed, while leading to important new conclusions. Because the electric field is singular at the tip of wedges, the original model developed by Johnson et al., which links the viscous fluid flow problem to the electrical conduction problem, is inappropriate for describing the high-frequency behavior of the viscous fluid flow through wedge-shaped porous media. In particular, in the case of small wedge angles, we show that the real part of the dynamic permeability behaves in the high-frequency regime as ℜ(k(ω))∝ω−(3/2)(ln (ω)+constant), which differs from the predictions of the Johnson et al. model [ℜ(k(ω))∝ω−(3/2)]. However, our results show that the classical Johnson et al. high frequency limit can be a good approximation of the viscous fluid flow if the electrical conduction problem is solved over a fluid domain truncated by a boundary layer having a thickness comparable to the viscous skin depth. In Paper II, we consider foam with perforated membranes involving different microstructural characteristic lengths: pore size, membrane aperture size, and membrane thickness. We assess the validity domain of the Johnson et al. approximation and test our modified high-frequency approximation for such porous materials.
Discovery of the zeroth law of helicity spectrum in the pre-inertial range of wall turbulence
Authors: Ali Sk Zeeshan , Dey Subhasish
Published: July 2022

We report an unprecedented existence of the zeroth law of helicity spectrum (i.e., the helicity spectrum becomes independent of the wavenumber) in the transition from production range to inertial range, herein termed the pre-inertial range, of wall turbulence. The zeroth law is explained by the superposition effect of the forward joint cascade of energy and helicity caused by twisting and stretching of wall-attached superstructures in an equilibrium layer. The phenomenological model perfectly predicts the zeroth law in the pre-inertial range. Experimental data support the existence of the zeroth law.
Non-iterative method for constructing valence antibonding molecular orbitals and a molecule-adapted minimum basis
Authors: Aldossary Abdulrahman , Head-Gordon Martin
Published: July 2022

While bonding molecular orbitals exhibit constructive interference relative to atomic orbitals, antibonding orbitals show destructive interference. When full localization of occupied orbitals into bonds is possible, bonding and antibonding orbitals exist in 1:1 correspondence with each other. Antibonding orbitals play an important role in chemistry because they are frontier orbitals that determine orbital interactions, as well as much of the response of the bonding orbital to perturbations. In this work, we present an efficient method to construct antibonding orbitals by finding the orbital that yields the maximum opposite spin pair correlation amplitude in second order perturbation theory (AB2) and compare it with other techniques with increasing basis set size. We conclude the AB2 antibonding orbitals are a more robust alternative to the Sano orbitals as initial guesses for valence bond calculations due to having a useful basis set limit. The AB2 orbitals are also useful for efficiently constructing an active space, and they work as good initial guesses for valence excited states. In addition, when combined with the localized occupied orbitals, and relocalized, the result is a set of molecule-adapted minimal basis functions that is built without any reference to atomic orbitals of the free atom. As examples, they are applied to the population analysis of halogenated methane derivatives, H–Be–Cl, and SF6, where they show some advantages relative to good alternative methods.
Total, state-selective, and angular-differential cross sections for electron capture in He2++H collisions in warm dense plasmas
Authors: Chen C. , Zhao G. P. , Qi Y. Y. , Liu L. , Chen Z. B. , Wang J. G.
Published: July 2022

The total, state-selective, and angular-differential cross sections for He2++H collision system in warm dense plasmas are studied by using the two-center atomic orbital close-coupling method in the energy range 0.1–300 keV/u. The calculations are performed for plasma density and temperature ranges ne ∼1018 to ∼1021 cm−3, Te = 0.3 eV–1.2 eV, typical for the H- and He-rich white dwarfs. The plasma environments are described by a unified screened potential involving electron degeneracy, finite-temperature gradient, and exchange-correlation effects. The results for H++H cases with the same plasma parameters are also presented for comparison to elucidate the discrepancies of plasma screening effects on the electron capture dynamics for collision systems with different nuclear symmetries. Moreover, classical Debye screening results are also given for comparison to clarify the effects of quantum correlations in warm dense plasmas on the electron capture dynamics. The present work is expected to provide theoretical and data support for the astrophysical plasmas.
Interfacial layers between ion and water detected by terahertz spectroscopy
Authors: Singh Abhishek K. , Doan Luan C. , Lou Djamila , Wen Chengyuan , Vinh Nguyen Q.
Published: July 2022

Dynamic fluctuations in the hydrogen-bond network of water occur from femto- to nanosecond timescales and provide insight into the structural/dynamical aspects of water at ion–water interfaces. Employing terahertz spectroscopy assisted with molecular dynamics simulations, we study aqueous chloride solutions of five monovalent cations, namely, Li, Na, K, Rb, and Cs. We show that ions modify the behavior of the surrounding water molecules and form interfacial layers of water around them with physical properties distinct from those of bulk water. Small cations with high charge densities influence the kinetics of water well beyond the first solvation shell. At terahertz frequencies, we observe an emergence of fast relaxation processes of water with their magnitude following the ionic order Cs > Rb > K > Na > Li, revealing an enhanced population density of weakly coordinated water at the ion–water interface. The results shed light on the structure breaking tendency of monovalent cations and provide insight into the properties of ionic solutions at the molecular level.
Effects of aromatic molecules inside argon clusters on the formation of multiply charged atomic ions in moderately intense nanosecond laser fields
Authors: Yao Yuzhong , Zhang Jie , Kong Wei
Published: July 2022

We report the effect of two molecular species, fluorene (C13H10, Fl) and 1, 3, 5-trichlorobenzene (C6H3Cl3, 3ClB), embedded in atomic argon clusters, on the generation of multiply charged atomic ions (MCAIs) in moderately intense nanosecond laser fields at 532 nm. The near resonant-enhancement of two photon absorption in the two aromatic species produces only a few low charge state (+2) atomic ions in a neat molecular cluster, but the enclosure of the same cluster with layers of Ar can significantly increase the charge state of MCAIs. The yields of singly charged atomic ions from the molecular species, such as H+, C+, and Cl+, are positively correlated with the number of molecules inside the Ar cluster, but the yields of the MCAI and Ar+ demonstrate opposite behaviors. A higher number of aromatic molecules are actually detrimental to the production of Ar+ and MCAIs. The results of exponential fittings of the yields of MCAIs at different laser intensities reveal a systematic change for the exponent of Ar+: with increasing concentrations of 3ClB in Ar clusters, the exponent decreases and eventually reaches the same value as those of MCAIs. These results are consistent with our previous hypothesis that the formation mechanism of MCAIs may be different from that of singly charged species and that the strong resonance of Ar3+ may play an important role in the overall energy absorption. Moreover, the effect of the molecular core seems to change the formation mechanism of Ar+ to that of MCAIs.
Top electrode modulated W/Ag/MgO/Au resistive random access memory for improved electronic synapse performance
Authors: Aziz Izzat , Ciou Jing-Hao , Kongcharoen Haruethai , Lee Pooi See
Published: July 2022

Resistive random access memory (ReRAM) is touted to replace silicon-based flash memory due to its low operating voltage, fast access speeds, and the potential to scale down to nm range for ultra-high density storage. In addition, its ability to retain multi-level resistance states makes it suitable for neuromorphic computing application. Here, we develop a cationic ReRAM with a sputtered MgO as the insulating layer. The resistive switching properties of the Ag/MgO/Au ReRAM stack reveal a strong dependence on the sputtering conditions of MgO. Due to the highly stable sputtered MgO, repeatable resistive switching memory is achieved with a low ON voltage of ∼0.7 V and a memory window of ∼1 × 105. Limiting Ag diffusion through a modified top electrode in the W/Ag/MgO/Au stack significantly reduces the abruptness of resistive switching, thereby demonstrating analog switching capability. This phenomenon is evident in the improved linearity and symmetry of potentiation and depression weight modulation pulses, demonstrating ideal Hebbian synaptic learning rules.
Analytical investigation of transient free convection and heat transfer of a hybrid nanofluid between two vertical parallel plates
Authors: Roy Nepal Chandra , Pop Ioan
Published: July 2022

Flow and heat transfer of transient free convection of a hybrid nanofluid between two parallel plates are theoretically investigated. Effects of a magnetic field, thermal radiation, and a heat source or a sink are considered. Laplace transforms are used to solve the dimensionless governing equations. Analytical expressions of velocity and temperature profiles and shear stress and rate of heat transfer are presented. Moreover, the correlations between the parameters and the shear stress and the rate of heat transfer have been derived. Increasing alumina and copper nanoparticle volume fractions reduces the velocity and temperature. However, the converse is seen for increasing heat source or sink parameter. For increasing radiation parameter, the temperature decreases but the velocity first increases. When 5% and 10% alumina nanoparticles are mixed with 5% copper nanoparticle, the heat transfer through the left wall increases about 14% and 30% and that through the right wall enhances about 21% and 44% in comparison to the heat transfer of pure fluid. For 5% and 10% copper nanoparticles with 5% alumina nanoparticle, the corresponding values are 15% and 31% and 22% and 45%, respectively. The heat source or sink intensity also plays an important role in the thermal field and heat transfer.
Multi-objective co-optimization of the guide vane closure law and rotor inertia in pumped-storage power system
Authors: Fu Xiaolong , Li Deyou , Wang Hongjie , Wei Xianzhu
Published: July 2022

Improving the transition safety and stability of pumped-storage hydropower plants supports the penetration of intermittent renewable energy into the grid. This paper presents the multi-objective optimization of the guide vane closure law and rotor inertia to reduce the rotational speed, water hammer pressure, and draft-tube vacuum by adopting genetic algorithms and a one-dimensional method of characteristic during load rejection transients. To reduce the increase in rotational speed to indirectly suppress pressure pulsations, a co-optimization of the guide vane closure law and rotor inertia is proposed. Results suggest that the above-mentioned co-optimization scheme can significantly reduce the increase in the rotational speed, water hammer pressure, and draft-tube vacuum and suppress the influence of pressure pulsations on the extreme pressure heads at the volute inlet and draft-tube inlet. Additionally, it can significantly reduce the transformation number of operation modes during pump-turbine load rejection transients.
Upconversion semiconductor interfaces by wafer bonding for photovoltaic applications
Authors: Sano Naoki , Nishigaya Kosuke , Tanabe Katsuaki
Published: July 2022

Efficient use of incident sunlight is an important key issue for the improvement of solar cell performance. Here, we propose and experimentally demonstrate photon upconversion material mediated semiconductor bonding as a concept of interfacial functionalization. Our wavelength-converting semiconductor interface comprises rare earth doped upconversion nanoparticles embedded in a hydrogel matrix. Advantageously, the bonding process is conducted at room temperature in ambient air. As a proof of principle, photocurrent enhancement in bonded Si solar cells is demonstrated. Our technical scheme could be useful to improve the performance and structural flexibility of various optoelectronic devices by delivering the preferred frequency to each of the optical components.
Effects of wear and shaft-shape error defects on the tribo-dynamic response of water-lubricated bearings under propeller disturbance
Authors: Cai Jianlin , Han Yanfeng , Xiang Guo , Wang Jiaxu , Wang Liwu
Published: July 2022

This study explores the effects of wear and shaft-shape error defects on the tribo-dynamic responses of water-lubricated bearings under nonlinear propeller disturbance using a numerical model. The model proposed in this paper is verified by comparing the results from experiments and simulations in published studies. Numerical simulation studies reveal the effects of nonlinear propeller disturbance on the dynamic behavior and lubrication performance, such as hydrodynamic force, contact force, and journal trajectory, of the water-lubricated bearings with wear and shaft-shape errors. In addition, the effects of the critical factors for wear and shaft-shape errors, including wear depth, deviation angle, magnitude, and waviness order, on the tribo-dynamic responses of water-lubricated bearings are identified. The results of numerical spectrum analyses show that the nonlinear disturbance significantly affects the dynamic behavior (shown as the fluctuation range of the journal trajectory increases), and reasonable wear parameters can improve the lubrication performance of the water-lubricated bearing. Moreover, the effects of shaft-shape errors on the transient hydrodynamic force, contact force, film thickness, pressure, and journal trajectory are greater than that of wear.
A complex network framework for studying particle-laden flows
Authors: Shri Vignesh K. , Tandon Shruti , Kasthuri Praveen , Sujith R. I.
Published: July 2022

Studying particle-laden flows is essential for understanding diverse physical processes such as rain formation in clouds, pathogen transmission, and pollutant dispersal. This work introduces a framework of complex networks to analyze the particle dynamics through a Lagrangian perspective. To illustrate this method, we study the clustering of inertial particles (small heavy particles) in Taylor–Green flow, where the dynamics depend on the particle Stokes number (St). Using complex networks, we can obtain the instantaneous local and global clustering characteristics simultaneously. Furthermore, from the complex networks derived from the particle locations, we observe an emergence of a giant component through a continuous phase transition as particles cluster in the flow field, thus providing novel insight into the spatiotemporal dynamics of particles such as the rate of clustering. Finally, we believe that complex networks have a great potential for analyzing the spatiotemporal dynamics of particle-laden flows.
Large-eddy simulation of Rayleigh–Bénard convection at extreme Rayleigh numbers
Authors: Samuel Roshan , Samtaney Ravi , Verma Mahendra K.
Published: July 2022

We adopt the stretched spiral vortex sub-grid model for large-eddy simulation (LES) of turbulent convection at extreme Rayleigh numbers. We simulate Rayleigh–Bénard convection (RBC) for Rayleigh numbers ranging from 106 to 1015 and for Prandtl numbers 0.768 and 1. We choose a box of dimensions 1:1:10 to reduce computational cost. Our LES yields Nusselt and Reynolds numbers that are in good agreement with the direct-numerical simulation (DNS) results of Iyer et al. [“Classical 1/3 scaling of convection holds up to Ra=1015,” Proc. Natl. Acad. Sci. U. S. A. 117, 7594–7598 (2020)] albeit with a smaller grid size and at significantly reduced computational expense. For example, in our simulations at Ra=1013, we use grids that are 1/120 times the grid resolution as that of the DNS [Iyer et al., “Classical 1/3 scaling of convection holds up to Ra=1015,” Proc. Natl. Acad. Sci. U. S. A. 117, 7594–7598 (2020)]. The Reynolds numbers in our simulations span 3 orders of magnitude from 1000 to 1 700 000. Consistent with the literature, we obtain scaling relations for Nusselt and Reynolds numbers as Nu∼Ra0.321 and Re∼Ra0.495. We also perform LES of RBC with periodic side walls, for which we obtain the corresponding scaling exponents as 0.343 and 0.477, respectively. Our LES is a promising tool to push simulations of thermal convection to extreme Rayleigh numbers and, hence, enable us to test the transition to the ultimate convection regime.
The effect of boundary conditions on the stability of two-dimensional flows in an annulus with permeable boundary
Authors: Ilin K. , Morgulis A.
Published: July 2022

Our aim is to study the effect of the outflow boundary conditions on the stability of incompressible flows in a domain with a permeable boundary. For this purpose, we examine the stability of the Couette flow with the radial throughflow between permeable cylinders. Most earlier studies of this flow employed the boundary conditions that prescribe all components of the flow velocity on both cylinders. Taking these boundary conditions as a reference point, we investigate the effect of imposing different outflow boundary conditions. These conditions prescribe the normal stress and either the tangential velocity or the tangential stress. It turns out that both sets of boundary conditions make the corresponding steady flows more unstable. In particular, it is shown that even the classical (purely azimuthal) Couette flow becomes unstable to two-dimensional perturbations if one of the cylinders is permeable and the normal stress (rather than normal velocity) is prescribed on that cylinder.
Modulation property of flexural-gravity waves on a water surface covered by a compressed ice sheet
Authors: Slunyaev A. V. , Stepanyants Y. A.
Published: July 2022

We study the nonlinear modulation property of flexural-gravity waves on a water surface covered by a compressed ice sheet of given thickness and density in a basin of a constant depth. For weakly nonlinear perturbations, we derive the nonlinear Schrödinger equation and investigate the conditions when a quasi-sinusoidal wave becomes unstable with respect to amplitude modulation. The domains of instability are presented in the planes of governing physical parameters; the shapes of the domains exhibit fairly complicated patterns. It is shown that, under certain conditions, the modulational instability can develop from shorter groups and for fewer wave periods than in the situation of deep-water gravity waves on a free water surface. The modulational instability can occur at the conditions shallower than that known for the free water surface kh = 1.363, where k is the wavenumber and h is the water depth. Estimates of parameters of modulated waves are given for the typical physical conditions of an ice-covered sea.
A simple improved low temperature correction for the hierarchical equations of motion
Authors: Fay Thomas P.
Published: July 2022

The study of open system quantum dynamics has been transformed by the hierarchical equations of motion (HEOM) method, which gives the exact dynamics for a system coupled to a harmonic bath at arbitrary temperature and system–bath coupling strength. However, in its standard form, this method is only consistent with the weak-coupling quantum master equation at all temperatures when many auxiliary density operators are included in the hierarchy, even when low temperature corrections are included. Here, we propose a new low temperature correction scheme for the termination of the hierarchy based on Zwanzig projection, which alleviates this problem and restores consistency with the weak-coupling master equation with a minimal hierarchy. The utility of the new correction scheme is demonstrated on a range of model systems, including the Fenna–Matthews–Olson complex. The new closure is found to improve convergence of the HEOM even beyond the weak-coupling limit and is very straightforward to implement in existing HEOM codes.
Green fluorescent cAMP indicator of high speed and specificity suitable for neuronal live-cell imaging
Authors: Kawata Seiko , Mukai Yuki , Nishimura Yumi , Takahashi Tomoyuki , Saitoh Naoto
Published: July 2022

Cyclic adenosine monophosphate (cAMP) is a canonical intracellular messenger playing diverse roles in cell functions. In neurons, cAMP promotes axonal growth during early development, and mediates sensory transduction and synaptic plasticity after maturation. The molecular cascades of cAMP are well documented, but its spatiotemporal profiles associated with neuronal functions remain hidden. Hence, we developed a genetically encoded cAMP indicator based on a bacterial cAMP-binding protein. This indicator “gCarvi” monitors [cAMP]iat 0.2 to 20 µM with a subsecond time resolution and a high specificity over cyclic guanosine monophosphate (cGMP). gCarvi can be converted to a ratiometric probe for [cAMP]iquantification and its expression can be specifically targeted to various subcellular compartments. Monomeric gCarvi also enables simultaneous multisignal monitoring in combination with other indicators. As a proof of concept, simultaneous cAMP/Ca2+imaging in hippocampal neurons revealed a tight linkage of cAMP to Ca2+signals. In cerebellar presynaptic boutons, forskolin induced nonuniform cAMP elevations among boutons, which positively correlated with subsequent increases in the size of the recycling pool of synaptic vesicles assayed using FM dye. Thus, the cAMP domain in presynaptic boutons is an important determinant of the synaptic strength.
Evolved interactions stabilize many coexisting phases in multicomponent liquids
Authors: Zwicker David , Laan Liedewij
Published: July 2022

Phase separation has emerged as an essential concept for the spatial organization inside biological cells. However, despite the clear relevance to virtually all physiological functions, we understand surprisingly little about what phases form in a system of many interacting components, like in cells. Here we introduce a numerical method based on physical relaxation dynamics to study the coexisting phases in such systems. We use our approach to optimize interactions between components, similar to how evolution might have optimized the interactions of proteins. These evolved interactions robustly lead to a defined number of phases, despite substantial uncertainties in the initial composition, while random or designed interactions perform much worse. Moreover, the optimized interactions are robust to perturbations, and they allow fast adaption to new target phase counts. We thus show that genetically encoded interactions of proteins provide versatile control of phase behavior. The phases forming in our system are also a concrete example of a robust emergent property that does not rely on fine-tuning the parameters of individual constituents.
The effect of figurative thought on basic level categorization
Authors: Győri Gábor
Published: July 2022

The definition for basic level categories relies on perceptual attributes, mostly on the perception of particular shape characteristics (Rosch, 1978). However, as is well known, there are cross-linguistic differences in basic level categorization with regard to the scope of the categories designated by the respective terms. Since word meanings do not directly correspond to perceptually definable basic level categories, these words do not designate the same range of referents, even though the attributes themselves do not necessarily differ cross-culturally. The same objects may belong to totally different linguistic categories, or even be assigned to levels above or below the perceptually basic one of the category system in different languages. The present theoretical study will explore why objects exhibiting similar perceptual characteristics come to be assigned to different linguistic categories. I suggest that the diversity originates in the figurative construals and ensuing conceptualizations underlying the lexicalization processes of these categories.
Physical and communicative force in Caused-Motion constructions
Authors: Panther Klaus-Uwe
Published: July 2022

Folk models of “mere” talk and “real” action shape the inferential properties of Transitive Caused-Motion (TCM) constructions with a human Patient as direct object. Physical action verbs like force into/out of semantically entail motion of the Patient into/out of a location. In contrast, constructions with speech act verbs like order into/out of pragmatically implicate motion of the Patient. Notwithstanding, cases like boo out of show that strong communicative pressure can result in entailed motion of the Patient. Finally, the contrast between constructional pairs like order somebody out of the car (stronger implicature of motion) vs. order somebody to get out of the car (weaker implicature of motion) supports the hypothesis of an iconic relationship between syntactic closeness and implicational strength.
“I think I belong over there”
Authors: Groff Cynthia , Mattar Daniela Vicherat
Published: July 2022

Experiences of belonging and unbelonging are constructed in multiple ways. Two young women share their stories of moving from north to south and their experiences of (un)belonging in the United States and Mexico. Analysis of the semi-structured interviews through interdisciplinary lenses highlights the contested nature of borders and the breaking down of pre-established categories. Beyond territorial borders, the experiences of these two US citizens of Mexican heritage reveal an ongoing negotiation of spatial, social and linguistic border spaces, blurring the distinctions between the two nationalities, multiple social groups, and the linguistic traditions to which they (choose to) belong. Different layers of identity and grounds for belonging intersect in the stories they tell. While family priorities and financial realities condition their choices and their mobility, the stories reveal agency and active (un)bordering on multiple scales, also exemplifying the potential of (un)bordering across academic disciplines.
Genre in World Englishes
Authors: Mühleisen Susanne
Published: July 2022

World Englishes and English in postcolonial contexts have been curiously neglected in an otherwise abundant research literature on text types and genres in English. This volume looks at the adaptation, transformation and emergence of genres in the particular cultural context of the Anglophone Caribbean. A comprehensive framework for the investigation of text production in postcolonial and global English communities is followed by empirically based case studies on specific text formats such as recipes, death notices and obituaries, letters to the editor, newspaper advice columns, radio phone-in programmes, online forums and the music genre calypso. Influences from oral versus literate culture as well as status and function of English versus Creole are considered by highlighting written, spoken and digital genres. All chapters present surveys from a historical and cross-cultural perspective before exploring specific linguistic and cultural features in the Caribbean texts. This volume will be highly relevant for researchers in World Englishes and Caribbean studies, postcolonial pragmatics, genre and media studies as well as linguistic anthropology.
Epithelial HNF4A shapes the intraepithelial lymphocyte compartment via direct regulation of immune signaling molecules
Authors: Lei Xuqiu , Ketelut-Carneiro Natalia , Shmuel-Galia Liraz , Xu Weili , Wilson Ruth , Vierbuchen Tim , Chen Yongzhi , Reboldi Andrea , Kang Joonsoo , Edelblum Karen L. , Ward Doyle , Fitzgerald Katherine A.
Published: July 2022

Hepatocyte nuclear factor 4 α (HNF4A) is a highly conserved nuclear receptor that has been associated with ulcerative colitis. In mice, HNF4A is indispensable for the maintenance of intestinal homeostasis, yet the underlying mechanisms are poorly characterized. Here, we demonstrate that the expression of HNF4A in intestinal epithelial cells (IECs) is required for the proper development and composition of the intraepithelial lymphocyte (IEL) compartment. HNF4A directly regulates expression of immune signaling molecules including butyrophilin-like (Btnl) 1, Btnl6, H2-T3, and Clec2e that control IEC–IEL crosstalk. HNF4A selectively enhances the expansion of natural IELs that are TCRγδ+ or TCRαβ+CD8αα+ to shape the composition of IEL compartment. In the small intestine, HNF4A cooperates with its paralog HNF4G, to drive expression of immune signaling molecules. Moreover, the HNF4A–BTNL regulatory axis is conserved in human IECs. Collectively, these findings underscore the importance of HNF4A as a conserved transcription factor controlling IEC–IEL crosstalk and suggest that HNF4A maintains intestinal homeostasis through regulation of the IEL compartment.
A scorpion toxin takes the sting out of T cell activation
Authors: Short Ben
Published: July 2022

JGP study identifies a novel peptide in scorpion venom that inhibits KV1.2 and KV1.3 channels and could form the basis for new treatments for autoimmune diseases.
Effect of gas flow on a helium/oxygen endoscopic plasma jet
Authors: Thulliez Max , Bastin Orianne , Remy Antoine , Nonclercq Antoine , Devière Jacques , Delchambre Alain , Reniers François
Published: July 2022

This experimental study characterized the effect of carrier gas flow on an endoscopic plasma jet. This system generates and transports helium plasma in a tube over several meters, along with a separate channel transporting oxygen to enhance plasma reactivity on site. The resulting plasma plume exiting the tube allows treatment of tissue surfaces in an endoscopic setting with a view to perform therapeutic operations in the gastrointestinal tract. In a closed cavity simulating the tract, the carrier gas flow was studied by a combined approach investigating plasma plume chemistry, fluid dynamics, and plasma effects on the surface of a hydrogel tissue model reporting oxidation. These three aspects are shown to be closely inter-related. Plasma plume length, intensity, and shape strongly depend on helium content, velocity, turbulence, and environment. Optical emission spectroscopy was used to show that the helium gas flow rate increases the amount of helium and reactive oxygen species (ROS) in the plume. Schlieren imaging was used to visualize the transition of the fluid from buoyant to laminar and finally turbulent depending on flow rate, with a backflow in a closed cavity. Finally, the frontal and radial treatment of the cavity was assessed by measuring ROS delivery to a KI-starch agarose gel model. Helium flow rate had a noticeable effect on the treatment distribution profile and treatment intensity, with different maxima for frontal and radial treatments. This combined approach, in an accurate simulation of the target configuration (i.e. a closed, cylindrical cavity), is necessary to optimize treatment, as its outcome depends on a balance between ROS production, transport, and distribution.
Promoting perpendicular magnetic anisotropy and Curie temperature in Cr2Ge2Te6/PtTe2 heterostructures
Authors: Qu Shuixian , Li Aolin , Jiang Nan , Zhang Dehe , Ouyang Fangping
Published: July 2022

The weak magnetic anisotropy and low Curie temperature of two-dimensional Cr2Ge2Te6 greatly restrict its application in spintronics. In this work, a simple but effective strategy has been proposed to promote the perpendicular magnetic anisotropy and Curie temperature of monolayer Cr2Ge2Te6, via stacking into van der Waals heterostructure with monolayer PtTe2. Based on first-principles calculations, the Cr2Ge2Te6/PtTe2 heterostructures are demonstrated to significantly enhance the magnetic anisotropy, which is improved from −0.06 meV Cr−1 for the monolayer into 0.24 meV Cr−1 for the heterostructure. By analyzing the orbit-resolved magnetic anisotropy and the projected density of states, it is revealed that the enhancement of magnetic anisotropy energy is closely related to interface Te atoms of monolayer Cr2Ge2Te6. The Curie temperature of the heterostructure is estimated to be 90 K by Monte Carlo simulation, increased by 300% compared with the value of 30 K for monolayer Cr2Ge2Te6. These results suggest the magnetic performance of Cr2Ge2Te6 can be significantly improved by van der Waals engineering. Compared with other methods, such as doping atoms or applying strain, this stacking-strategy is more convenient and controllable. Although there are still important challenges toward the room-temperature ferromagnetism of two-dimensional Cr2Ge2Te6 and other semiconductors, our work has proved a new approach to solve this problem and is of reference value for the design of novel magnetic heterostructures.
A formalism to assess the accuracy of nuclear-structure weak interaction effects in precision β-decay studies
Authors: Glick-Magid Ayala , Gazit Doron
Published: July 2022

Multiple high precision β-decay measurements are being carried out these days on various nuclei, in search of beyond the Standard Model (SM) signatures. These measurements necessitate accurate SM theoretical predictions to be compared with. Motivated by the experimental surge, we present a formalism for such a calculation of β-decay observables, with controlled accuracy, based on a perturbative analysis of the theoretical observables related to the phenomena, including high order nuclear recoil and shape corrections. The accuracy of the corrections is analyzed by identifying a hierarchy of small parameters, related to the low-momentum transfer characterizing β-decays. Furthermore, we show that the sub-percent uncertainties, targeted by ongoing and planned experiments, entail an accuracy of the order of 10% for the solution of the nuclear many-body problem, which is well within the reach of modern nuclear theory for light to medium mass nuclei.
Fusion of 12C + 24Mg at extreme sub-barrier energies
Authors: Montagnoli G , Stefanini A M , Jiang C L , Hagino K , Niola F , Brugnara D , Čolović P , Colucci G , Corradi L , Depalo R , Fioretto E , Goasduff A , Pasqualato G , Scarlassara F , Szilner S , Zanon I
Published: July 2022

A recent experiment on 12C + 24Mg sub-barrier fusion was performed. Standard coupled-channels calculations clearly over-estimated the low energy cross sections and there was indication of a maximum of the astrophysical S factor vs energy. In the present work further measurements have been performed on the same system, and we extended the excitation function to lower energies down to σ ≃ 4 μb, confirming the existence of the hindrance phenomenon. Additional energy points near the barrier were added as well. In agreement with the result of previous experiment, the hindrance energy threshold is observed to correspond to a remarkably large cross section. The present new data allow to better define the S-factor maximum, that is well fitted using two parametrizations of either the hindrance or the adiabatic model. We also performed coupled-channels calculations using a Woods–Saxon potential. Far below the barrier we observe that the coupling strengths decrease and tend to vanish, indeed one-dimensional tunnelling calculations well reproduce the excitation function. Further precise cross section measurements at slightly lower energies are needed to discriminate between the adiabatic and hindrance models. This would give a reliable guidance for the extrapolation to the systems of astrophysical interest, like 12C + 12C and 16O + 16O.
Cr2XTe4 (X = Si, Ge) monolayers: a new type of two-dimensional high-T
C Ising ferromagnetic semiconductors with a large magnetic anisotropy
Authors: Bai Yihang , Shi Rui , Wu Yaxuan , Wang Bing , Zhang Xiuyun
Published: July 2022

Two-dimensional (2D) ferromagnetic semiconductor (FMS) provides the ideal platform for the development of quantum information technology in nanoscale devices. However, most of them suffer from low Curie temperature and small magnetic anisotropic energy (MAE), severely limiting their practical application. In this work, by using first-principles calculations, we predicted two stable 2D materials, namely, Cr2SiTe4 and Cr2GeTe4 monolayers. Interestingly, both of them are intrinsic direct band gap FMSs (∼1 eV) with a large magnetization (8 µ
B f.u.−1) and sizable MAE (∼500 μ
eV Cr−1). Monte Carlo simulations based on Heisenberg model suggest markedly high Curie temperatures of these monolayers (∼200 K). Besides, their high mechanical, dynamical, and thermal stabilities are further verified by elastic constants, phonon dispersion calculations, and ab initio molecular dynamics simulations. The outstanding attributes render Cr2XTe4 (X = Si, Ge) monolayers broadening the candidates of 2D FMS for a wide range of applications.
Spin–phonon dispersion in magnetic materials
Authors: Gu Mingqiang , Bai Y H , Zhang G P , George Thomas F
Published: July 2022

Microscopic coupling between the electron spin and the lattice vibration is responsible for an array of exotic properties from morphic effects in simple non magnets to magnetodielectric coupling in multiferroic spinels and hematites. Traditionally, a single spin–phonon coupling constant is used to characterize how effectively the lattice can affect the spin, but it is hardly enough to capture novel electromagnetic behaviors to the full extent. Here, we introduce a concept of spin–phonon dispersion to project the spin moment change along the phonon crystal momentum direction, so the entire spin change can be mapped out. Different from the phonon dispersion, the spin–phonon dispersion has both positive and negative frequency branches even in the equilibrium ground state, which correspond to the spin enhancement and spin reduction, respectively. Our study of bcc Fe and hcp Co reveals that the spin force matrix, that is, the second-order spatial derivative of spin moment, is similar to the vibrational force matrix, but its diagonal elements are smaller than the off-diagonal ones. This leads to the distinctive spin–phonon dispersion. The concept of spin–phonon dispersion expands the traditional Elliott-Yafet theory in nonmagnetic materials to the entire Brillouin zone in magnetic materials, thus opening the door to excited states in systems such as CoF2 and NiO, where a strong spin-lattice coupling is detected in the THz regime.
Anomalous photoluminescence of InAs surface quantum dots: intensity enhancement and strain control by underlying quantum dots
Authors: Mohammadi H , Roca R C , Kamiya I
Published: July 2022

Strain control and photoluminescence (PL) enhancement of InAs surface quantum dots (SQDs), exposed to ambient conditions, have been achieved by introducing underlying buried quantum dots (BQDs). The PL wavelength has been tuned from 1270 to as long as 1780 nm, redshifted as the size of the SQDs is reduced. This is in strong contrast to standard QDs, in which blueshift is observed from smaller QDs following basic quantum mechanics. Here, smaller SQDs, both in height and base area, as observed by atomic force microscopy, were obtained with wider GaAs spacer thickness between the SQDs and BQDs. The result strongly suggests that strain and related effects dominate the electronic properties of the SQDs rather than their size, and that a change in the complex strain field occurs through the spacer. The underlying BQDs also serve as effective carrier reservoirs. A PL intensity enhancement of 17 fold was observed as the GaAs spacer thickness was reduced from 150 to 10 nm. A large portion of the photoexcited carriers is initially captured and stored in the BQDs. When sufficient carriers are transferred to fill non-radiative surface states, the excess may be transferred to the SQDs enhancing the luminescence.
Co-doped CeO2/N–C nanorods as a bifunctional oxygen electrocatalyst and its application in rechargeable Zn-air batteries
Authors: Xiang Wenjuan , Li Yanling , Wu Mengxue , Ma Jinfu , Sheng Zhilin
Published: July 2022

The development of electrocatalysts for both oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) with high-activity and atability still remain great challenges for rechargeable Zn-air batteries. Herein, a new type of Co-doped Ce–N–C bifunctional electrocatalyst has been synthesized through a simple two-step method, which realizes the high dispersion of Co3O4 on the CeO2 carbon frame and stabilizes its specific surface area. Benefiting from the synergistic interaction between Co3O4 and CeO2, the conductivity of the electrocatalyst is improved and the oxygen reduction reaction/oxygen storage properties are promoted. The resultant Co3O4-CeO2@N–C catalyst shows remarkable ORR activity with the high initial potential (E
0 = 0.8 V), the large limiting current density (j
L = 6 mA cm−2), and a low Tafel slope (81 mV dec−1). In full cell tests, Co3O4-CeO2@NC as the oxygen electrode exhibites superior charge/discharge capacity and excellent cycle stability. The assembled Zn-air battery achieves a maximum power density of 110 mW cm−2 at a current density of 180 mA cm−2, and a high specific capacity of 780 mAh g−1 at a discharge current density of 10 mA cm−2.
The noble metals M (M = Pd, Ag, Au) decorated CeO2 catalysts derived from solution combustion method for efficient low-temperature CO catalytic oxidation: effects of different M loading on catalytic performances
Authors: Cui Xiuxiu , Zhang Xu , Yang Yaqi , Chen Ting , Wang Yude
Published: July 2022

The noble metal nanoparticles have attracted attention due to their excellent catalytic performance for CO oxidation at low temperatures. M-CeO2 (M = Pd, Ag, Au) catalysts with different atomic ratios of M/Ce were deposited via solution combustion method. Among them, 3 at% Pd-CeO2, 5 at% Ag-CeO2 and 1 at% Au-CeO2 catalysts have better catalytic performances. Especially, 5 at% Ag-CeO2 catalyst shows better low-temperature CO oxidation performance. The catalytic activity for CO oxidation follows the follows the following sequence: 5 at% Ag-CeO2 (T50 = 69 °C) > 3 at% Pd-CeO2 (T50 = 99 °C) >1 at% Au-CeO2 (T50 = 115 °C). Meanwhile, the catalysts are characterized by means of powder x-ray diffraction, scanning electron microscope, transmission electron microscopy, Raman spectroscopy, x-ray photoelectron spectroscopy, Brunauer–Emmett–Teller and H2-TPR. The characterization results show that the 5 at% Ag-CeO2 catalyst has excellent catalytic activity due to the good dispersion of Ag nanoparticles, the specific surface area of the material, and the reduction catalyst between different valence ions. Moreover, the surface of the catalyst enhances the mutual synergy, effectively promotes the generation of oxygen vacancies, and increases the active oxygen content of the catalyst surface. Finally, the catalytic mechanism of M-CeO2 catalysts is summarized.
All electrospun fabrics based piezoelectric tactile sensor
Authors: Luo Yunyun , Zhao Libo , Luo Guoxi , Li Min , Han Xiangguang , Xia Yong , Li Ziping , Lin Qijing , Yang Ping , Dai Liyan , Niu Gang , Wang Xiaozhang , Wang Jiuhong , Lu Dejiang , Jiang Zhuangde
Published: July 2022

Tactile sensors have been widely used in the areas of health monitoring and intelligent human-machine interface. Flexible tactile sensors based on nanofiber mats made by electrospinning can meet the requirements of comfortability and breathability for wearing the body very well. Here, we developed a flexible and self-powered tactile sensor that was sandwich assembled by electrospun organic electrodes and a piezoelectric layer. The metal-free organic electrodes of thermal plastic polyurethane (PU) nanofibers decorated with multi-walled carbon nanotubes were fabricated by electrospinning followed by ultrasonication treatment. The electrospun polyvinylidene fluoride-trifluoroethylene (PVDF-TrFE) mat was utilized as the piezoelectric layer, and it was found that the piezoelectric performance of PVDF-TrFE nanofiber mat added with barium titanate (BaTiO3) nanoparticles was enhanced about 187% than that of the pure PVDF-TrFE nanofiber mat. For practical application, the as-prepared piezoelectric tactile sensor exhibited an approximative linear relationship between the external force and the electrical output. Then the array of fabricated sensors was attached to the fingertips of a glove to grab a cup of water for tactile sensing, and the mass of water can be directly estimated according to the outputs of the sensor array. Attributed to the integrated merits of good flexibility, enhanced piezoelectric performance, light weight, and efficient gas permeability, the developed tactile sensor could be widely used as wearable devices for robot execution end or prosthesis for tactile feedback.