bluuebunny/crossref_metadata_2025 huggingface dataset:
Direct biexciton generation in Si nanocrystal by a single photon
Authors: Fomichev S. A. , Burdov V. A.
Published: June 2024

It has been shown theoretically that a strong quantum confinement regime in Si nanocrystals promotes highly efficient simultaneous excitation of two electron–hole pairs (biexciton) by a single photon. The rate (inverse lifetime) of biexciton generation has been calculated analytically as a function of the nanocrystal radius. The size-dependence of the rate in Si nanocrystal turns out to be sharp enough—in fact, it is inversely proportional to the sixth power of the radius. At radii values approaching a nanometer, the lifetime of biexciton generation falls into the nanosecond range. The threshold energy of this process in Si nanocrystals is exactly equal to twice the nanocrystal gap in contrast to the case of nanocrystals formed of direct-bandgap semiconductors, where the direct photon-induced creation of a biexciton with such an energy is, in fact, suppressed.
Mixed-mode oscillations of an atomic force microscope in tapping mode
Authors: Song Peijie , Li Xiaojuan , Cui Jianjun , Chen Kai , Chu Yandong
Published: June 2024

In the phenomenon of mixed-mode oscillations, transitions between large-amplitude and small-amplitude oscillations may lead to anomalous jitter in the probe of a tapping mode atomic force microscope (TM-AFM) during the scanning process, thereby affecting the accuracy and clarity of the topographical images of the tested sample’s surface. This work delves deeply into various mixed-mode oscillations and the corresponding formation mechanisms in TM-AFM under low-frequency resonant excitation. Through a detailed analysis of bifurcation sets of the fast subsystem, we found that the system’s mixed-mode oscillations encompass the typical two coexisting branches and the novel three coexisting branches of equilibrium point attractors. In the stable case, a certain transition pattern in phase trajectory can be observed involving two jumps and four jumps, switching between quiescent and spiking states. In the bi-stable case, the trajectory undergoes distinct transitions decided by whether to pass through or crossover the middle branch of attractors when bifurcation occurs. By applying basin of attraction and fast–slow analysis methods, we unfold the dynamic mechanism of mixed-mode oscillations with distinct switching patterns. Our research contributes to a better understanding of complex oscillations of TM-AFM and provides valuable insights for improving image quality and measurement precision while mitigating detrimental oscillations.
Formation dynamics of branching structure in the slippery DLCA model
Authors: Hirata Koichi , Araki Takeaki
Published: June 2024

We numerically investigated the aggregation dynamics and resulting network structures of colloidal gels using the slippery diffusion-limited cluster aggregation (DLCA) model. In this model, bonds are irreversibly formed upon the particle contacts, but the angles among them are not fixed, unlike the conventional DLCA. This allows clusters to be deformed in the process of aggregation. By characterizing the aggregation dynamics and using a reduced network scheme, our simulation revealed two distinct branching structure formation routes depending on the particle volume fraction ϕ. In lower volume fraction systems (ϕ ≤ 8%), the deformations of small-size clusters proceed prior to the percolation. When the Maxwell criterion is satisfied and the clusters become mechanically stable, the formation of the branching structure is nearly completed. After forming the branching structures, they aggregate and form a larger percolating network. Then, the aggregation proceeds through the elongation and straightening of the chain parts of the network. In higher volume fraction systems (ϕ > 8%), on the other hand, the clusters percolate, and a fine and homogeneous branching structure is formed at the early stage of the aggregation. In the aging stage, it collapses into a denser and more heterogeneous structure and becomes more stable. Our quantitative analyses of the branching structure will shed light on a new strategy for describing the network formation and elasticity of colloidal gels.
Weak antilocalization and sign inversion of magnetoresistance on CaRuO3 epitaxial films
Authors: Alagoz H. S. , Egilmez M. , Hamdan N. , Mustafa F. , Jung J. , Chow K. H. , El-Khatib S.
Published: June 2024

CaRuO3 is a prototypical perovskite oxide among the Ruddlesden–Popper series with multi-exotic physical properties on the verge of quantum criticality. Unlike the case of the well-known ferromagnetic SrRuO3, the literature on the physical properties of the CaRuO3 system is scarce with no consensus about its magnetic and transport ground states. This work provides a detailed study of the magnetotransport properties of 300 nm CaRuO3 epitaxial films grown on single crystalline SrTiO3 and LaAlO3 substrates. The magnetic and electronic ground states in tensile strained CaRuO3/SrTiO3 films and compressively strained CaRuO3/LaAlO3 films are found to be distinctly different. In particular, in zero magnetic field, the high-temperature resistivity of both films show a T1/2 non-Fermi liquid behavior. Cooling below 30 K, CaRuO3/SrTiO3 undergoes metal–insulator-transition ascribed by 3D weak localization, with signs of weak ferromagnetic-like domains. By contrast, the transport data of the nonmagnetic CaRuO3/LaAlO3 film below 30 K, show T3/2 non-Fermi liquid type behavior. Magnetoresistance in CaRuO3/SrTiO3 shows combination of weak antilocalization and weak localization behaviors deep in the insulating side, emphasizing the existence of spin–orbit coupling and the strong influence of ferromagnetic impurities. Moreover, the nonlinearity signals in CaRuO3/SrTiO3 Hall measurements could be described by anomalous Hall effects. Interestingly, below 30 K, magnetoresistance and Hall in CaRuO3/LaAlO3 change sign, indicating an inversion from hole-like to electron-like behavior. We discuss the sensitivity of the 300 nm CaRuO3/SrTiO3 and CaRuO3/LaAlO3 films to the 30 K temperature, an additional quantum critical feature to the ruthenate oxides.
Orientational dynamics of the water layer adjacent to Au surface accelerated by polarization effect
Authors: Zhai Zhidong , Chen Qun , Wang Yin , Ren Wei , Guo Pan
Published: June 2024

The orientation and rearrangement of water on a gold electrode significantly influences its physicochemical heterogeneous performance. Despite numerous experimental and theoretical studies aimed at uncovering the structural characteristics of interfacial water, the orientational behavior resulting from electrode-induced rearrangements remains a subject of ongoing debate. Here, we employed molecular dynamics simulations to investigate the adaptive structure and dynamics properties of interfacial water on Au(111) and Au(100) surfaces by considering a polarizable model for Au atoms in comparison with the non-polarizable model. Compared to the nonpolarizable systems, the polarization effect can enhance the interaction between water molecules and the gold surface. Unexpectedly, the rotational dynamics directly associated with the orientational behavior of water adjacent to the gold surface is accelerated, thereby reducing the hydrogen bond lifetime. The underlying mechanism for this anomalous phenomenon originates from the polarization effect, which induces the attraction of the positive hydrogen atoms to the surface by the negative image charge. This leads to a change in orientation that disrupts the hydrogen bonds in the first water layer and subsequently accelerates reorientation dynamics of water molecules adjacent to the gold surface. These results shed light on the intricate interplay between polarization effects and water molecule dynamics on metal surfaces, establishing the foundation for the rational regulation of the orientation of interfacial water.
Helium aggregation and surface morphology near grain boundaries in plasma-facing tungsten
Authors: Hammond Karl D. , Maroudas Dimitrios , Wirth Brian D.
Published: June 2024

We conduct molecular dynamics simulations of helium in tungsten to study the interaction of helium with grain boundaries. Model systems with grain boundary planes perpendicular to the surface and parallel to the surface are considered. The net attraction of mobile helium to the grain boundary results in a “depleted region” within approximately 3.5 nm of the grain boundary plane at low fluence, and once on the plane of the grain boundary, helium transport slows considerably. Helium retention is also strongly affected by the grain boundaries and their density: grain boundary planes approximately 6 nm beneath the plasma-facing surface and parallel to the surface tend to reduce the maximum bubble size due to the attraction of mobile clusters to the grain boundary plane, which lowers the concentration of helium near the surface (where it is being implanted); grain boundaries perpendicular to the surface tend to increase retention due to retention on the grain boundary plane. For grain boundaries parallel to the surface, the strong gettering effect of the grain boundaries on helium results in essentially no helium penetration through the grain boundary during the first 1.5 μs of plasma exposure at a flux of 1.6×1025 m−2s−1, corresponding to fluences on the order of 1020 m−2. Coarse-grained simulations capable of capturing the long-term dynamics of helium aggregation near grain boundaries would be required to determine whether these effects would have any measurable impact on phenomena, such as tungsten fuzz growth.
Chiral perovskite-CdSe/ZnS QDs composites with high circularly polarized luminescence performance achieved through additive-solvent engineering
Authors: Zhu Hongmei , Wang Qingqian , Chen Wei , Sun Kun , Zhong Huaying , Ye Taikang , Wang Zhaojin , Zhang Wenda , Müller-Buschbaum Peter , Sun Xiao Wei , Wu Dan , Wang Kai
Published: June 2024

Chiral perovskite materials are being extensively studied as one of the most promising candidates for circularly polarized luminescence (CPL)-related applications. Balancing chirality and photoluminescence (PL) properties is of great importance for enhancing the value of the dissymmetry factor (glum), and a higher glum value indicates better CPL. Chiral perovskite/quantum dot (QD) composites emerge as an effective strategy for overcoming the dilemma that achieving strong chirality and PL in chiral perovskite while at the same time achieving high glum in this composite is very crucial. Here, we choose diphenyl sulfoxide (DPSO) as an additive in the precursor solution of chiral perovskite to regulate the lattice distortion. How structural variation affects the chiral optoelectronic properties of the chiral perovskite has been further investigated. We find that chiral perovskite/CdSe–ZnS QD composites with strong CPL have been achieved, and the calculated maximum |glum| of the composites increased over one order of magnitude after solvent-additive modulation (1.55 × 10−3 for R-DMF/QDs, 1.58 × 10−2 for R-NMP-DPSO/QDs, −2.63 × 10−3 for S-DMF/QDs, and −2.65 × 10−2 for S-NMP-DPSO/QDs), even at room temperature. Our findings suggest that solvent-additive modulation can effectively regulate the lattice distortion of chiral perovskite, enhancing the value of glum for chiral perovskite/CdSe–ZnS QD composites.
Utilizing topological invariants for encoding and manipulating chiral phonon devices
Authors: Li Xiaozhe , Long Yang , Wang Tingting , Zhou Yan , Zhang Lifa
Published: June 2024

As a fundamental degree of freedom, phonon chirality is expected to promote the development of quantum information technology just like electron spin. Currently, central to this area is the realization of efficient transmission and control of chiral information. In this paper, we propose an approach by integrating topological theory, leveraging topologically invariant Chern numbers, to encode hexagonal lattice systems. Our investigation reveals the presence of topologically protected chiral interface states within the shared band gaps of both trivial and non-trivial system units. By precisely modulating the magnetic field distribution within the encoding system, we can effectively manipulate the topological pathways. Building upon this framework, we design and implement a chiral phonon three-port device. Through dynamic calculations, we demonstrate the transmission process of chiral information, showcasing the chiral phonon switching effect and logical OR operation. Our findings not only establish a fundamental mechanism for the manipulation and control of phonon chiral information but also provide a promising direction for research in harnessing chirality degrees of freedom in practical applications.
Probing the electric and thermoelectric response of ferroelectric 2H and 3R α-In2Se3
Authors: Rahimi M. , Sobnath K. , Chen L. , Mallet F. , Lafarge P. , Barraud C. , Alekhin A. , Brochard-Richard C. , Bouaziz M. , Chaste J. , Ouerghi A. , Della Rocca M. L.
Published: June 2024

Two-dimensional van der Waals ferroelectric materials play an important role in a wide spectrum of semiconductor technologies and device applications. Integration of ferroelectrics into 2D-layered material-based devices is expected to offer intriguing working principles and add desired functionalities for next-generation electronics. Here, we investigate the electric and thermoelectric properties of thin layers of the 2H and 3R polymorphs of α-In2Se3 embedded in solid-state three-terminal devices. Charge transport measurements reveal a hysteretic behavior that can be ascribed to the effect of ferroelectric polarization at the metal electrode/2D semiconductor interfaces. The thermoelectric investigation of the same devices unveils a well-defined negative signal of the order of 100–200 μV/K in absolute value for the 2H polymorph, showing a slight modulation as a function of the gate voltage. An analogous but noisy thermoelectric voltage is measured for devices based on the 3R polymorph, where indeed a constant finite transversal offset in the 100 μV-few mV range is detected, which does not depend on the applied temperature gradient. We argue that these experimental observations are related to a strong residual in-plane ferroelectric polarization in the 3R α-In2Se3 polymorph thin layer. Our results show that the thermoelectric response is a fine probe of the ferroelectric character of 2D layered α-In2Se3.
Similarity study of low-pressure microwave argon plasma based on numerical simulation
Authors: Wang Lin , Wu Jiamin , Liao Changjiang , Gao Jinwei
Published: June 2024

This article mainly proposes a similarity analysis method for the breakdown process of microwave argon plasma, which can easily obtain high-power microwave (HPM) breakdown features for argon plasma in microwave components with extremely large- or small-scale. The electromagnetic-plasma fluid model is proposed and solved by the finite element method. The preconditions for a similarity principle of gas breakdown in a microwave frequency band are proposed. In plasma breakdown regions with a proportional size, the ratio of incident microwave frequency f to gas pressure p (f/p) and reduced electric field (E/p) in them remain the same. Numerical results show that in the microwave frequency band, the breakdown process between similar structures also conforms to the similarity principle, especially after the argon plasma breakdown region is stabilized, numerical results are in good agreement with the theoretical values. The intensity of electric field is directly proportional to scale-down factor k, electron density is directly proportional to the square of scale-down factor k2, and electron energy is almost independent of scale-down factor k. Meanwhile, the distribution trends of electric field, electron density, and electron energy during the microwave argon breakdown process are also roughly the same, respectively. This research method can provide theoretical guidance for analyzing the HPM breakdown effect in extremely large or extremely small microwave components.
Double perovskite Bi2FeMnO6/TiO2 thin film heterostructure device for neuromorphic computing
Authors: Li Dong-Liang , Zhong Wen-Min , Tang Xin-Gui , He Qin-yu , Jiang Yan-Ping , Liu Qiu-Xiang
Published: June 2024

Multiferroic materials have important research significance in the fields of magnetic random-access memory, ferroelectric random-access memory, resistive random-access memory, and neuromorphic computing devices due to their excellent and diverse physical properties. In this work, a solution of Bi2FeMnO6 was prepared using a solution-based method, and an Au/Bi2FeMnO6/TiO2 heterostructure device was fabricated on a Si substrate. X-ray diffraction and transmission electron microscopy data indicate that the Bi2FeMnO6 films have hexagonal R3c symmetry structures. The Bi2FeMnO6 film exhibits ferroelectricity with a fine remanent polarization. In addition, the Bi2FeMnO6-based devices have excellent switching ratios of 6.37 × 105. A larger switching ratio can provide a multi-resistance state for the device, which is beneficial for the simulation of synapses. Hence, it effectively emulates excitatory postsynaptic currents, paired-pulse facilitation, and long-term plasticity of synapses and achieves recognition accuracy of 95% in neuromorphic computing. We report a promising material for the development of various nonvolatile memories and neuromorphic synaptic devices.
The effects of different anode manufacturing methods on deep levels in 4H-SiC p+n diodes
Authors: Alfieri G. , Bolat S. , Nipoti R.
Published: June 2024

The manufacture of bipolar junctions is necessary in many 4H-SiC electronic devices, e.g., junction termination extensions and p+in diodes for voltage class >10 kV. However, the presence of electrically active levels in the drift layer that act as minority charge carrier lifetime killers, like the carbon vacancy (VC), undermines device performance. In the present study, we compared p+n diodes whose anodes have been manufactured by three different methods: by epitaxial growth, ion implantation, or plasma immersion ion implantation (PIII). The identification of the electrically active defects in the drift layers of these devices revealed that a substantial concentration of VC is present in the diodes with epitaxial grown or ion implanted anode. On the other hand, no presence of VC could be detected when the anode is formed by PIII and this is attributed to the effects of strain in the anode region. Our investigation shows that PIII can be a useful technique for the manufacture of bipolar devices with a reduced concentration of lifetime killer defects.
Comparative study of photo-induced electronic transport along ferroelectric domain walls in lithium niobate single crystals
Authors: Ding L. L. , Beyreuther E. , Koppitz B. , Kempf K. , Ren J. H. , Chen W. J. , Rüsing M. , Zheng Y. , Eng L. M.
Published: June 2024

Ferroelectric domain wall conductivity (DWC) is an intriguing and promising functional property that can be elegantly controlled and steered through a variety of external stimuli such as electric and mechanical fields. Optical-field control, as a noninvasive and flexible tool, has rarely been applied so far, but it significantly expands the possibility for both tuning and probing DWC. On the one hand, as known from second-harmonic or Raman micro-spectroscopy, the optical approach provides information on DW distribution and inclination, while simultaneously probing the DW vibrational modes; on the other hand, photons might be applied to directly generate charge carriers, thereby acting as a functional and spectrally tunable probe to deduce the local absorption properties and bandgaps of conductive DWs. Here, we report on investigating the photo-induced DWC (PI-DWC) of three lithium niobate crystals, containing a very different number of DWs, namely: (A) none, (B) one, and (C) many conductive DWs. All three samples are inspected for their current–voltage behavior in darkness and for different illumination wavelengths swept from 500 nm down to 310 nm. All samples show their maximum PI-DWC at 310 nm; moreover, sample (C) reaches PI-DWCs of several microampere. Interestingly, a noticeable PI-DWC is also observed for sub-bandgap illumination, hinting toward the existence and decisive role of electronic in-gap states that contribute to the electronic charge transport along DWs. Finally, complementary conductive atomic force microscopy investigations under illumination proved that the PI-DWC indeed is confined to the DW area and does not originate from photo-induced bulk conductivity.
Improving photodetection response time of ReS2 devices through double-sided oxidation
Authors: Zhou Leyun , Qi Renxian , Wang Chenglin , Guo Xitao , Lin Liangliang , Cai Zhengyang , Xiao Shaoqing , Gu Xiaofeng , Nan Haiyan
Published: June 2024

Response time is a crucial factor limiting the performance of two-dimensional material-based photodetectors. The underlying mechanisms of response have recently garnered significant attention in the ongoing research. Supported ReS2 on substrates has been found to be predominantly governed by the photofloating gate effect, known to be slower compared to photoelectric effects. In this study, we present findings demonstrating suspended ReS2 devices. Removing the substrate results in a substantial enhancement in optical response by an order of magnitude compared to substrate-supported devices. Deep trap states induced by inherent defects are identified as the primary contributors to prolonged response times. Engineering these ReS2 trap states through defect manipulation can significantly improve response times. Here, we effectively modulate the response speed of ReS2 through gentle oxygen plasma treatments. The response speed of ReS2 is improved by two orders of magnitude. Under the optimal processing conditions of 50 W, 30 Pa, and 10 s, we observed rising and falling response times of 45 and 106 ms, respectively, under illumination at a wavelength of 637 nm. Additionally, we demonstrate that the input–output characteristic of photocurrent provides valuable insights into the underlying opto-physical processes responsible for generating photocurrent.
On the increased interfacial resistance of hydrogen in carbon nanotube arrays and its effect on gas mixture separation
Authors: Kratzer Matthew M. , Bhatia Suresh K. , Klimenko Alexander Y.
Published: June 2024

We outline a surface scattering kernel for rarefied gas flows through ideally ordered nanomaterials, such as high aspect ratio carbon nanotubes. The derived model allows for a comparison of the tangential momentum accommodation coefficient, and, hence, the total effective friction, for different species of gases as a function of the particle diameter. This surface kernel is incorporated with a Fokker–Planck model as an approximation to transport of a rarefied gas through ideally ordered carbon nanotubes. The results of this analysis predict that H2 experiences higher friction in such systems in comparison with larger molecules such as CH4. The results are proposed as a potential explanation of the reduced gas transport of hydrogen gas in nanoporous systems.
Analytical investigation of vesicle dynamics via the modified Riemann–Liouville fractional derivative: Mittag-Leffler function solution and comparative analysis with Caputo’s derivative
Authors: Azroul Elhoussine , Diki Ghizlane
Published: June 2024

The solution of fractional differential equations is a significant focus of current research, given their prevalence in various fields of application. This paper introduces an innovative exploration of vesicle dynamics using Jumarie’s modified Riemann–Liouville fractional derivative within a five-dimensional fractional rigid sphere model. The study reveals an exact solution through the Mittag-Leffler function, providing a deep understanding of intricate vesicle dynamics, including alternative motions, such as tank-treading with over-damped and under-damped vesicle oscillations, respectively, TT-OD and TT-UD. A comparative analysis with Caputo’s derivative emphasizes the effectiveness of these fractional derivatives, contributing not only to theoretical insights but also practical implications in applied mathematics and biophysical systems. The findings advance our understanding of complex vesicle behaviors, particularly in mimicking real cell-like behaviors, and pave the way for further research and applications in the field.
The direct role of nuclear motion in spin–orbit coupling in strongly correlated spin systems
Authors: Willatt M. J. , Alavi A.
Published: June 2024

The interaction between the magnetic moment of an electron and the magnetic field generated by a moving charge is one component of the spin–orbit interaction. The nuclei in a molecule or solid are charged, are generally in vibrational motion, and so contribute to this interaction, but the direct coupling between nuclear momentum and electron spin is normally ignored in discussions of spin-forbidden phenomena such as transitions between states of different spin, even when the nuclei are recognized as playing a fundamental role (spin–vibronic coupling). Here, we investigate the spin–orbit interaction in a Heisenberg model interacting with vibrating point charges representing nearby bridging ligands. To reach the model, we apply second order perturbation theory to the Hubbard model with the spin–orbit interaction. In contrast to the other components of the spin–orbit interaction, the part that directly couples the momentum of the charge and electron spin appears at first order as an effective magnetic field at each site. We find that the inclusion of this nuclear-motion induced spin–orbit coupling can increase the rate of otherwise spin-forbidden transitions between different spin states of the Heisenberg model by many orders of magnitude. This overlooked interaction may, therefore, play a significant role in spin-forbidden phenomena such as spin relaxation in coupled spin-qubits.
Atomic imaging and optical properties of InAs/In0.5Ga0.5As0.5Sb0.5 type II superlattice
Authors: Shi Chao , Wang Dengkui , Li Weijie , Fang Xuan , Zhang Bin , Wang Dongbo , Hao Yu , Fang Dan , Zhao Hongbin , Du Peng , Li Jinhua
Published: June 2024

High-quality III–V quantum structures, advanced epitaxial technologies, and characterization methods are essential to drive the development of infrared optoelectronic materials and devices. As an important component of type II superlattices, InAs/InxGa1−xAsySb1−y would play an important role in the field of high-performance infrared detectors due to their excellent luminescence efficiency and high crystal quality. However, their interfacial characteristics and the associated minority carrier lifetime are still difficult to identify. In this paper, an atomic imaging technique was used to identify the arrangement and distribution of elements of the InAs/In0.5Ga0.5As0.5Sb0.5 superlattice. Our results confirm the epitaxy mechanism that the quaternary alloy consists of two kinds of ternary alloy in one monolayer. Moreover, by separating the cation and anion columns in the elementally resolved atomic images of the InAs/In0.5Ga0.5As0.5Sb0.5 superlattice, we demonstrate that the interfacial atomic intermixing is less than one molecular layer thickness. Therefore, benefiting from excellent interface quality, InAs/In0.5Ga0.5As0.5Sb0.5 superlattice exhibited high radiation recombination efficiency in the long-wave infrared band (∼8.5 μm), and longer minority carrier lifetime (∼810 ns at 90 K).
Influence of particle stacking modes on the fluidization characteristics of biomass particles in binary particle systems
Authors: Wang Bo , Bai Ling , Yu Haihan , Agarwal Ramesh , Zhou Ling
Published: June 2024

Spouted bed is widely used in biomass combustion and other industrial production due to the advantages of good heat transfer performance and sufficient gas–solid mixing. In order to achieve higher heat and mass transfer performance and conversion efficiency, inert particles are often added to assist in the fluidization of biomass particles. However, the stacking patterns of different particles in a binary particle system can have some effects on particle flow, distribution, and bed stability. Therefore, in this study, the computational fluid dynamics–discrete element method was used to analyze the particle fluidization characteristics under four different particle stacking modes in a spouted bed. The results show that the average bed height of larger spherocylindrical particles is prioritized in binary particle systems. The void fraction of spherocylindrical particles tends to increase in the near-wall region, whereas spherical particles tend to decrease. When the binary particles are mixed at the initial moment, the change rule of vertical velocity of the two particles remains consistent. In addition, the vertical velocities of two kinds of particles when layered stacking is used are gradually close to each other only after a period of time. In addition, the orientation angle of the spherocylindrical particles in the spouted bed tends to be horizontal for both the single-component spherocylindrical particle system and the wall effect attenuates this phenomenon.
Solvent effect in H-BEA catalyzed cyclohexanol dehydration reaction
Authors: Li Sha , Chen Huimin
Published: June 2024

The solvent effect on H-BEA catalyzed cyclohexanol dehydration was investigated in water, dioxane, and cyclohexanol. The dynamic evolution of the Brønsted acid site of zeolite and its interaction with reactant molecules in different solvents were explored with ab initio molecular dynamics simulations, providing reliable configuration sampling to obtain configurations at equilibrium. Solvent profoundly changes the adsorption as well as the dehydration reaction of cyclohexanol in H-BEA, where the reaction is determined to follow the E2 mechanism in water and dioxane but the E1 mechanism in cyclohexanol untill saturation uptake. Near saturation uptake, all three solvents significantly reduce the cyclohexanol dehydration rates in H-BEA. Cyclohexanol loading also dramatically affects the kinetics of the dehydration reaction, displaying an overall decreasing trend with a local minimum present at intermediate loading of 6 molecules per unit cell, which is a result of the entropic effect associated with greater freedom of motion of the transition state. Rigorous quantification of enthalpy and entropy contributions to cyclohexanol adsorption and activation shed light on the solvent effect of zeolite-catalyzed alcohol dehydration.
Optimization study of a Z-type airflow cooling system of a lithium-ion battery pack
Authors: Argade Santosh , De Ashoke
Published: June 2024

The present study aims to optimize the structural design of a Z-type flow lithium-ion battery pack with a forced air-cooling system known as BTMS (battery thermal management system). The main goal is to minimize Tmax (maximum temperature) and ΔTmax (maximum temperature difference) while ensuring an even airflow distribution within the battery module. The present study thoroughly investigates critical factors, such as the inlet air velocity, tapered inlet manifold, and the number of secondary outlets, to evaluate their impact on thermal performance and airflow uniformity within the battery module. Increasing the inlet air velocity from 3 to 4.5 m/s significantly improves the thermal cooling performance of the BTMS, resulting in a decrease of 4.57 °C (10.05%) in Tmax and 0.29 °C (9.79%) in ΔTmax compared to the original 3 m/s velocity. Further, the study assesses the significance of a tapered inlet manifold as a critical factor, revealing its substantial impact on cooling performance and temperature reductions in battery cells 3–9. It also facilitates a more uniform airflow distribution, decreasing the velocity difference between channel 9 and channel 1 from 3.32 to 2.50 m/s. Incorporating seven secondary outlets significantly improves the heat dissipation ability of the BTMS, resulting in a decrease of 0.894 °C (2.18%) in Tmax and 2.23 °C (72.84%) in ΔTmax compared to the configuration with 0 secondary outlets. By optimizing these parameters, the aim is to enhance BTMS's capabilities, improving LIB (lithium-ion battery) packs' performance and reliability. The optimized structural design parameters proposed in this study yield practical applications that extend beyond theoretical insights, impacting diverse fields reliant on lithium-ion battery technology. Through enhanced thermal management systems, applications in electric vehicles and portable electronics are poised to experience improved performance and longevity. Furthermore, these advancements inform the development of next-generation battery packs, promising reduced overheating risks and extended battery life. Such innovations are critical in energy storage systems for renewable energy applications and electric vehicle technology, facilitating faster charging times and increased driving range. Moreover, the implications extend to aerospace applications, ensuring the reliability of batteries in extreme environmental conditions.
Quantum linear magnetoresistance and magnetic-field-induced metal–insulator transition in the Weyl semimetal candidate HgSe
Authors: Lonchakov A. T. , Bobin S. B.
Published: June 2024

In ultrapure single HgSe crystal, a large linear magnetoresistance with a record magnitude of 15 000% in mercury chalcogenides was discovered in a quantum limit at the magnetic field of 12 T in the temperature range of 20–40 K. The effect was described in terms of Abrikosov's theory of quantum linear magnetoresistance, thus providing its first experimental confirmation. In the temperature range of 0.4–4.2 K, a magnetic field-induced metal–insulator transition appeared in the ultrapure HgSe. Estimates show that the critical magnetic field of this transition of 6.8 T satisfies the criterion for stabilization of a condensed Wigner phase in the quantum limit.
Determination of band offsets at the interfaces of NiO, SiO2, Al2O3, and ITO with AlN
Authors: Wan Hsiao-Hsuan , Li Jian-Sian , Chiang Chiao-Ching , Xia Xinyi , Hays David C. , Al-Mamun Nahid Sultan , Haque Aman , Ren Fan , Pearton Stephen J.
Published: June 2024

The valence and conduction band offsets at the interfaces between NiO/AlN, SiO2/AlN, Al2O3/AlN, and ITO/AlN heterointerfaces were determined via x-ray photoelectron spectroscopy using the standard Kraut technique. These represent systems that potentially would be used for p-n junctions, gate dielectrics, and improved Ohmic contacts to AlN, respectively. The band alignments at NiO/AlN interfaces are nested, type-I heterojunctions with a conduction band offset of −0.38 eV and a valence band offset of −1.89 eV. The SiO2/AlN interfaces are also nested gap, type-I alignment with a conduction band offset of 1.50 eV and a valence band offset of 0.63 eV. The Al2O3/AlN interfaces are type-II (staggered) heterojunctions with a conduction band offset of −0.47 eV and a valence band offset of 0.6 eV. Finally, the ITO/AlN interfaces are type-II (staggered) heterojunctions with conduction band offsets of −2.73 eV and valence band offsets of 0.06 eV. The use of a thin layer of ITO between a metal and the AlN is a potential approach for reducing contact resistance on power electronic devices, while SiO2 is an attractive candidate for surface passivation or gate dielectric formation on AlN. Given the band alignment of the Al2O3, it would only be useful as a passivation layer. Similarly, the use of NiO as a p-type layer to AlN does not have a favorable band alignment for efficient injection of holes into the AlN.
Sequence dependence of critical properties for two-letter chains
Authors: Panagiotopoulos Athanassios Z.
Published: June 2024

Histogram-reweighting grand canonical Monte Carlo simulations are used to obtain the critical properties of lattice chains composed of solvophilic and solvophobic monomers. The model is a modification of one proposed by Larson et al. [J. Chem. Phys. 83, 2411 (1985)], lowering the “contrast” between beads of different types to prevent aggregation into finite-size micelles that would mask true phase separation between bulk high- and low-density phases. Oligomeric chains of lengths between 5 and 24 beads are studied. Mixed-field finite-size scaling methods are used to obtain the critical properties with typical relative accuracies of better than 10−4 for the critical temperature and 10−3 for the critical volume fraction. Diblock chains are found to have lower critical temperatures and volume fractions relative to the corresponding homopolymers. The addition of solvophilic blocks of increasing length to a fixed-length solvophobic segment results in a decrease of both the critical temperature and the critical volume fraction, with an eventual slow asymptotic approach to the long-chain limiting behavior. Moving a single solvophobic or solvophilic bead along a chain leads to a minimum or maximum in the critical temperature, with no change in the critical volume fraction. Chains of identical length and composition have a significant spread in their critical properties, depending on their precise sequence. The present study has implications for understanding biomolecular phase separation and for developing design rules for synthetic polymers with specific phase separation properties. It also provides data potentially useful for the further development of theoretical models for polymer and surfactant phase behavior.
Improving equitable access to publicly funded bariatric surgery in Queensland, Australia
Authors: Cross Megan , Paxton Jody , Wykes Katie , Chikani Viral , Hopkins George , Teppala Srinivas , Scuffham Paul ,   on behalf of the Clinical and Operational Reference Group
Published: June 2024

Background People living in regional Queensland, Australia, have less access to health care than their metropolitan neighbours; a gap that is wider if they are also of Aboriginal and Torres Strait Islander ethnicity. The Bariatric Surgery Initiative (BSI) aims to provide metabolic bariatric surgery as a public service accessible to all Queenslanders for patients with morbid obesity according to need, regardless of location or ethnicity. Methods We investigated the BSI’s progress in closing the metro-regional gap by comparing the distribution of referrals for surgery with the geographic and ethnic spread of obesity across Queensland in 2017–2019. Results Regional Queensland is home to 59.8% of Queensland’s individuals with obesity, whereas 40.2% live in metropolitan Brisbane. In contrast, 47.8% of referrals were from regional areas, with 52.2% received from Brisbane. We found that more patients from metropolitan than regional areas underwent metabolic bariatric surgery, probably due to a paucity of referrals from regional locations. Aboriginal and Torres Strait Islander peoples were able to access the service and all patients realised significant health benefits after surgery. Conclusions The BSI improved access to this service, and inequities in metro-regional access may depend on patient choice and healthcare provider awareness of the BSI. Trial registration This initiative was a quality improvement study focused on providing access to care rather than a clinical trial; as such it was not registered as a clinical trial.
Identification of two archaeal GDGT lipid–modifying proteins reveals diverse microbes capable of GMGT biosynthesis and modification
Authors: Garcia Andy A. , Chadwick Grayson L. , Liu Xiao-Lei , Welander Paula V.
Published: June 2024

Archaea produce unique membrane-spanning lipids (MSLs), termed glycerol dialkyl glycerol tetraethers (GDGTs), which aid in adaptive responses to various environmental challenges. GDGTs can be modified through cyclization, cross-linking, methylation, hydroxylation, and desaturation, resulting in structurally distinct GDGT lipids. Here, we report the identification of radical SAM proteins responsible for two of these modifications—a glycerol monoalkyl glycerol tetraether (GMGT) synthase (Gms), responsible for covalently cross-linking the two hydrocarbon tails of a GDGT to produce GMGTs, and a GMGT methylase (Gmm), capable of methylating the core hydrocarbon tail. Heterologous expression of Gms proteins from various archaea inThermococcus kodakarensisresults in the production of GMGTs in two isomeric forms. Further, coexpression of Gms and Gmm produces mono- and dimethylated GMGTs and minor amounts of trimethylated GMGTs with only trace GDGT methylation. Phylogenetic analyses reveal the presence of Gms homologs in diverse archaeal genomes spanning all four archaeal superphyla and in multiple bacterial phyla with the genetic potential to synthesize fatty acid–based MSLs, demonstrating that GMGT production may be more widespread than previously appreciated. We demonstrate GMGT production in three Gms-encoding archaea, identifying an increase in GMGTs in response to elevated temperature in twoArchaeoglobusspecies and the production of GMGTs with up to six rings inVulcanisaeta distributa.The occurrence of such highly cyclized GMGTs has been limited to environmental samples and their detection in culture demonstrates the utility of combining genetic, bioinformatic, and lipid analyses to identify producers of distinct archaeal membrane lipids.
3.3 million years of stone tool complexity suggests that cumulative culture began during the Middle Pleistocene
Authors: Paige Jonathan , Perreault Charles
Published: June 2024

Cumulative culture, the accumulation of modifications, innovations, and improvements over generations through social learning, is a key determinant of the behavioral diversity across
Homo sapiens
populations and their ability to adapt to varied ecological habitats. Generations of improvements, modifications, and lucky errors allow humans to use technologies and know-how well beyond what a single naive individual could invent independently within their lifetime. The human dependence on cumulative culture may have shaped the evolution of biological and behavioral traits in the hominin lineage, including brain size, body size, life history, sociality, subsistence, and ecological niche expansion. Yet, we do not know when, in the human career, our ancestors began to depend on cumulative culture. Here, we show that hominins likely relied on a derived form of cumulative culture by at least ~600 kya, a result in line with a growing body of existing evidence. We analyzed the complexity of stone tool manufacturing sequences over the last 3.3 My of the archaeological record. We then compare these to the achievable complexity without cumulative culture, which we estimate using nonhuman primate technologies and stone tool manufacturing experiments. We find that archaeological technologies become significantly more complex than expected in the absence of cumulative culture only after ~600 kya.
StaufenC facilitates utilization of the ERAD pathway to transport dsRNA through the endoplasmic reticulum to the cytosol
Authors: Koo Jinmo , Palli Subba Reddy
Published: June 2024

RNA interference (RNAi) is more efficient in coleopteran insects than other insects. StaufenC (StauC), a coleopteran-specific double-stranded RNA (dsRNA)-binding protein, is required for efficient RNAi in coleopterans. We investigated the function of StauC in the intracellular transport of dsRNA into the cytosol, where dsRNA is digested by Dicer enzymes and recruited by Argonauts to RNA-induced silencing complexes. Confocal microscopy and cellular organelle fractionation studies have shown that dsRNA is trafficked through the endoplasmic reticulum (ER) in coleopteran Colorado potato beetle (CPB) cells. StauC is localized to the ER in CPB cells, and StauC-knockdown caused the accumulation of dsRNA in the ER and a decrease in the cytosol, suggesting that StauC plays a key role in the intracellular transport of dsRNA through the ER. Using immunoprecipitation, we showed that StauC is required for dsRNA interaction with ER proteins in the ER-associated protein degradation (ERAD) pathway, and these interactions are required for RNAi in CPB cells. These results suggest that StauC works with the ERAD pathway to transport dsRNA through the ER to the cytosol. This information could be used to develop dsRNA delivery methods aimed at improving RNAi.
汉语句子的基本单位刍议
Authors: Li Jinman
Published: June 2024

抽象的

汉语中“词”的界定一直是个棘手的话题。本文从广受国内外学者关注的汉语关系从句的加工单位说起，综合多源证据，探讨汉语句子的基本分析单位是否是“词”的问题。文章首先基于前期汉语关系从句自定速阅读加工研究中的相关实验刺激材料，对比分析同一实验、同一研究、同类研究之间采用的加工单位情况；然后综合来自眼动实验、容错现象、自然语言处理、汉英构词对比等多个研究领域中的证据，进一步审视汉语句子基本单位的问题。最后，我们从语言学视角，梳理国内外学者对汉语中“字”、“词”看法的演变，认为可以将汉语句子单位纳入类型学视野下进行考量，探索更合理普适的解决方案，促进语言相关领域的研究。
The relationship between teachers’ pedagogical practices in CLIL and the development of students’ foreign language oral proficiency
Authors: Sato Takanori
Published: June 2024

This study investigated the relationship between foreign language (FL) oral proficiency development and teachers’ pedagogical practices in content and language integrated learning (CLIL). A one-group pretest-posttest design was employed to analyze changes in Japanese university students’ FL proficiency over time, alongside classroom observations and interviews that captured their teachers’ classroom pedagogies in CLIL courses. The results generally indicated that students improved their capacity to achieve communicative goals but failed to exhibit progress in oral linguistic competence. The former outcome was attributed to predominantly meaning-focused instruction, the use of dialogic pedagogy, and ample opportunities to practice FL speaking. In contrast, the absence of explicit language instruction and limited practice of fluency development tasks was perceived to lead to the latter outcome. These findings not only contribute to understanding the effects of CLIL on FL learning, but also shed light on the specific pedagogy-related factors that contribute to FL proficiency development.
Influence of light source modulation on detection performance of trace-level SF6 fault gas using photoacoustic spectroscopy
Authors: Zhu Kexin , Zeng Fuping , Huang Zujian , Jiang Xinghai , Chao Xianzong , Feng Xiaoxuan , Tang Ju
Published: June 2024

Photoacoustic spectroscopy (PAS) is highly valued in gas detection for its outstanding sensitivity and rapid response. Addressing its limited precision in trace gas analysis, scholars have taken numerous measures to optimize structural and modify the size of acoustic sensors and photoacoustic cells (PACs). Nevertheless, advancements in laser modulation remain understudied due to technical difficulties. This paper theoretically examines the effects of intensity modulation with square wave signals and wavelength modulation involving sawtooth and sinusoidal. In this paper, a theoretical approach is proposed to examine the effects of intensity modulation with square wave signals and wavelength modulation involving sawtooth and sinusoidal signals. Experimental measurements were performed using parameters obtained in preliminary experiments. We constructed an experimental setup with varied-length PACs to bolster experimental dependability, focusing on H2S as the target gas to compare the two laser modulation techniques. The results exhibited that at low frequencies, intensity modulation outperforms wavelength modulation. At resonance frequencies, however, wavelength modulation could provide stronger signals’ intensity. Modulation frequency considerations are therefore crucial when choosing a modulation method for PAS gas detection. Without specific frequency requirements, a second harmonic modulation at resonance is recommended. This study provides guidance on selecting laser modulation methods for PAS, potentially refining the technique’s application in trace gas analysis.