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Screw dislocation is important not only for understanding plastic deformation of crystals but also for optical and electrical properties of materials. However, characterizations of screw dislocations are still challenging since there is almost no atom distortion when viewed along the dislocation line. In particular, although it is theoretically known that shear strains in heteroepitaxy systems may be relaxed via screw dislocation grids, the specific structures and thickness-dependent evolutions of these grids are still largely unknown. Here, by using orthorhombic [001]-oriented DyScO

Flexoelectricity is an effective tool in modulating the crystallographic structures and properties of oxides for multifunctional applications. However, engineering the nonuniform strain to obtain tunable flexoelectric behaviors at the atomic scale remains an ongoing challenge in conventional substrate-imposed ferroelectric films. Here, the regulatable flexoelectric behaviors are demonstrated at atomic scale in [110]-oriented BiFeO3 thin films, which are triggered by the strain-field coupling of high-density interfacial dislocations. Using aberration-corrected scanning transmission electron microscopy, the asymmetric polarization rotation around the single dislocation is revealed, which is induced by the gradient strain fields of the single dislocation. These strain fields are highly correlated to generate huge strain gradients between neighboring dislocations, and thereby, serial flexoelectric responses are engineered as a function of dislocation spacings in thicker BiFeO3 films. This work opens a pathway for the modulation of flexoelectric responses in ferroelectrics, which could be extended to other functional materials to create exotic phenomena.

SrTiO3 is generally paraelectric with centrosymmetric structure exhibiting unique quantum fluctuation related ferroelectricity. Here we reveal highly polar and periodic polarization waves in SrTiO3 at room temperature, which is stabilized by periodic tensile strains in a sandwiched PbTiO3/SrTiO3/PbTiO3 structure. Scanning transmission electron microscopy reveals that periodic a/c domain structures in PbTiO3 layers exert unique periodic tensile strains in the ultrathin SrTiO3 layer and consequently make the highly polar and periodic states of SrTiO3. The as-received polar SrTiO3 layer features peak polar ion displacement of ∼0.01 nm and peak tetragonality of ∼1.07. These peak values are larger than previous results, which are comparable to that of bulk ferroelectric PbTiO3. Our results suggest that it is possible to integrate large and periodic strain state in oxide films with exotic properties, which in turn could be useful in optical applications and information addressing when used as memory unit.

Depleting regulatory T cells from the tumor microenvironment is an attractive strategy for enhancing immunotherapy. Here we developed a humanized antibody against CD25 (H11E11-2V1) with Treg-biased binding. This antibody has a medium affinity to CD25 (KD=8.9nM), weaker than Daclizumab (KD=1.5nM) and RG6292 (KD=4.5nM). Primary T cells activated with CD3 and CD28 beads had increased CD25 expression. H11E11-2V1 bound to Treg (CD4+Foxp3+) with a concentration as low as 0.07nM, similar to RG6292, while it has no detectable binding to activated Teff (CD4+Foxp3-) with a concentration below 2nM (vs. RG6292 below 0.7nM). In addition, H11E11-2V1 did not block IL-2 signaling in NK-92 cells, which expressed CD25 on the cell surface, while Daclizumab blocked the IL-2 signaling. Daclizumab inhibited T cell proliferation (ki67+%) and activation (Granzyme B+%), but not by RG6292 and H11E11-2V1. In vitro cytotoxicity assay indicated that H11E11-2V1 with modified Fc to enhance ADCC specifically depletes Treg from activated primary T cells at a minimal concentration of 0.07nM (vs. RG6292 at 0.14nM) while leaving 90% of Teff intact. In the in vivo MC38 murine tumor model with mice whose CD25 was replaced with human CD25, H11E11-2V1 given by I.P. injection suppressed tumor growth with higher efficiency than RG6292. These results suggested that H11E11-2V1 was an excellent candidate therapeutical antibody against CD25 for cancer therapy. Citation Format: Yuxuan Gao, Feng He, Hao Peng, Kefei Wu, Hui Zhao, Yanpeng Feng, Feng Hao, Guojin Wu, Jinying Ning. Depletion of regulatory T cells without interruption of IL-2 signaling by antibody against CD25 for enhancing antitumor immunity [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 574.

In order to achieve high resolution in Successive Approximation Register (SAR) Analog to Digital Converter (ADC), a novel noncoupling capacitor split capacitor array structure is proposed, which solves the coupling capacitor mismatch problem in the traditional split capacitor array structure. This paper analyzes the structure and its capacitor array mismatch. Based on the structure and analysis, a 12-bit SAR ADC is designed and implemented in GSMC 0.11 [Formula: see text]m CMOS process. The measured results show that the Signal to Noise Ratio (SNR) is 72.61 dB and Effective Number Of Bits (ENOB) is 11.77 bit, which prove the advantages of this structure in the design of high resolution SAR ADC.

The physical properties of perovskite oxides are very sensitive to oxygen vacancy structures, and an unambiguous acquaintance of vacancy structures of thin films is the precondition for application...

In the present study, a ternary combination of graphitic carbon nitride (g-C3N4), carbon nanodots (CDs), and ferrous ion (Fe(II)) was proposed. The g-C3N4/CDs/Fe(II) composite was prepared through ...

SrTiO

Periodic arrays of electric dipole waves in ferroelectric oxides can be stabilized at room temperature by quenching., A dipole wave is composed of head-to-tail connected electric dipoles in the form of sine function. Potential applications in information carrying, transporting, and processing are expected, and logic circuits based on nonlinear wave interaction are promising for dipole waves. Although similar spin waves are well known in ferromagnetic materials for their roles in some physical essence, electric dipole wave behavior and even its existence in ferroelectric materials are still elusive. Here, we observe the atomic morphology of large-scale dipole waves in PbTiO3/SrTiO3 superlattice mediated by tensile epitaxial strains on scandate substrates. The dipole waves can be expressed in the formula of y = Asin (2πx/L) + y0, where the wave amplitude (A) and wavelength (L) correspond to 1.5 and 6.6 nm, respectively. This study suggests that by engineering strain at the nanoscale, it should be possible to fabricate unknown polar textures, which could facilitate the development of nanoscale ferroelectric devices.

Common pursuits of developing nanometric logic and neuromorphic applications have motivated intensive research studies into low-dimensional resistive random-access memory (RRAM) materials. However, fabricating resistive switching medium with inherent stability and homogeneity still remains a bottleneck. Herein, we report a self-assembled uniform biphasic system, comprising low-resistance 3 nm-wide (Bi0.4,La0.6)FeO3-δ nanosheets coherently embedded in a high-resistance (Bi0.2,La0.8)FeO3-δ matrix, which were spinodally decomposed from an overall stoichiometry of the (Bi0.24,La0.76)FeO3-δ parent phase, as a promising nanocomposite to be a stable and endurable RRAM medium. The Bi-rich nanosheets accommodating high concentration of oxygen vacancies as corroborated by X-ray photoelectron spectroscopy and electron energy loss spectroscopy function as fast carrier channels, thus enabling an intrinsic electroforming-free character. Surficial electrical state and resistive switching properties are investigated using multimodal scanning probe microscopy techniques and macroscopic I-V measurements, showing high on/off ratio (∼103) and good endurance (up to 1.6 × 104 cycles). The established spinodal decomposition-driven phase-coexistence BLFO system demonstrates the merits of stability, uniformity, and endurability, which is promising for further application in RRAM devices.

In this research, high strength fiber reinforced concrete (HSFRC) was used to replace the normal strength concrete (NSC) in steel-concrete composite beams to improve their working performance, which might change the static performance of stud connectors. Firstly, push-out tests were conducted to investigation on the static performance of stud connectors in steel-HSFRC composite beams and compared with steel-NSC composite beams. Studs of 8 sizes, 13 mm, 16 mm, 19 mm and 22 mm in diameter and 80 mm and 120 mm in height were adopted to study the influence of stud dimension. The test phenomenon shown that the crack resistance of HSFRC was better than that of NSC, and there were some splitting cracks on NSC slabs whereas no visible cracks on HSFRC slabs when specimens failed. Next, the load-slip curves of studs were analyzed and a typical load-slip curve was proposed which was divided into four stages. In addition, the effects of test parameters were analyzed according to the characteristic points of load-slip curve. Compared with NSC slab, HSFRC slab could provide greater restraining force to the studs, which improved the shear capacity and stiffness of studs while suppressed the ductility of studs. The shear capacity, stiffness and ductility of studs would significantly increase with the increasement of stud diameter and the studs with large diameter were more suitable for steel-HSFRC composite beams. The stud height had no obvious influence on the static performance of studs. Finally, based on the test results, the empirical formulas for load-slip curve and shear capacity of stud connectors embedded in HSFRC were developed which considered the influence factors more comprehensively and had better accuracy and applicability than previous formulas.

The multiple polarization states driven by polarization rotation could trigger giant piezoelectric responses in electromechanical sensors. Theoretically and experimentally, polarization rotation in...

Topological defects showing exotic properties and diverse functionalities provide us a potential utilization in nanoscale electronic devices. However, the formation mechanism and density manipulati...

Controlling domain width, orientation, and patterns in oxide ferroelectrics are not only important for fundamental research but also for potential electronic application. Here, a series of PbTiO3 thin films under various cooling rates were deposited on (110)-oriented NdScO3 substrates by pulsed laser deposition and investigated by using conventional transmission electron microscopy, Cs-corrected scanning TEM and piezoresponse force microscopy. Contrast analysis and electron diffraction revealed that PbTiO3 films are a1/a2 domain patterns under large tensile strains with different cooling rates. The a1/a2 domains distribute periodically and the domain width increases with decrease in the cooling rates. Upon increasing the cooling rate, the domain density increases and the domain configurations become complicated. There are special square frame-like domain patterns with charged domain walls found in the PTO films with the fast cooling rate. PFM measurement shows that the PTO films with high cooling rate exhibit enhanced piezoresponse behavior which is ascribed to the high density domain/domain walls and special domain configurations. The formation mechanism of the different domain configurations is discussed in terms of the effect of cooling rates, defects and thermal kinetics. These results are expected to provide useful information for domain/domain wall control and thus facilitate further modulation of the properties for potential applications.

High-index ferroelectric thin films show excellent dielectricity, piezoelectricity and switching behaviors. Understanding the misfit strain relaxation behavior may prove beneficial to gaining insights into the high-quality growth of high-index ferroelectric films. In this study, ferroelectric PbTiO3 thin films were deposited on the (101)-oriented (La, Sr)(Al, Ta)O3 substrate by pulsed laser deposition and were investigated using (scanning) transmission electron microscopy. Two types of misfit dislocations with line directions of and [010] were found at the interface. The dislocation exhibited Burgers vectors of a [011] or [01 $\overline{1}$ 1], while the [010] dislocation featured Burgers vectors of a[ $\overline{1}$ 01]. The former might be generated by gliding, and the latter by climbing. We propose that the misfit strain relaxation in this film system basically results from the formation of dislocations and the residual misfit strain is relaxed via the formation of 90° ac domains.

Strongly correlated oxides exhibit multiple degrees of freedoms, which can potentially mediate exotic phases with exciting physical properties, such as the polar vortex recently found in ferroelectric oxide films. A polar vortex is stabilized by competition between charge, lattice, and/or orbital degrees of freedom, which displays vortex–ferroelectric phase transitions and emergent chirality, making it a potential candidate for designing information storage and processing devices. Here, by a combination of controlled film growth and aberration-corrected scanning transmission electron microscopy, we obtain nanoscale vortex arrays in [110]-oriented BiFeO3 films. These vortex arrays are stabilized in ultrathin BiFeO3 layers sandwiched by two coherently grown orthorhombic scandate layers, exhibiting a ferroelectric morphotropic phase boundary constituted by a mixed-phase structure of polar orthorhombic BiFeO3 and rhombohedral BiFeO3. Clear polarization switching and piezoelectric signals were observed in thes...

A sufficient understanding of mechanical performance of self-anchored suspension bridge with double-sided steel box girder is essential for design and normal use as such bridges are widely built in urban bridge. Using the Yunlongwan Bridge which is a suspension bridge with ultra-wide double-sided steel box girder as an example, this paper investigates its deformation and mechanical performance under vehicle load. Firstly, based on the field test results, the deformation performance of the bridge and the stress distribution of the main girder are analysed, with emphasis on the shear lag effect of double-sided steel box girder. Then, a multiscale model of the bridge was built, and the accuracy of the model was verified by comparison with the test data. Finally, the influence of design parameters on the mechanical behaviour of double-sided steel box girder is studied by numerical simulation. The results show that the deformation of the bridge has good symmetry, there is obvious shear lag effect on the main girder, and the U-rib thickness, diaphragm spacing, and vehicle load could significantly affect the stress of the main girder top plate. The obtained analytical results lead to a better understanding of the mechanical performance and provide reference for the design of self-anchored suspension bridge with double-sided steel box girder.

This article takes a rotorcraft crash accident as an example. Through multi-angle analysis, it is judged that the accident was caused by breaking the tail beam in the air. The reason why the main rotor swings excessively against the tail beam is analyzed. Finally, the preventive measures for the main rotor excessive swing and impacting the tail beam are discussed.

For antenna of aircraft, which play a very importance role for communication safety, Once the failure of antenna, the aircraft will lost necessary guidance or without connecting with ground and support center. For mechanical failure for antennas of Boeing and Airbus, the installation structure was many important. In this case, one VHF2 fault was found in the A330 aircraft of one China Airline after flight. To investigation the root cause of the failure antenna, the surface of the antenna was observation by fluorescence detection, but no animal muscle tissue or blood was found. The fracture, macrostructure and microstructure were analysis by optical, scanning electron microscope, result show the fracture was fatigue. The fracture process of VHF2 of the aircraft VHF antenna may be that the bonding layer cracks first, and then fatigue fracture of the metal part of the leading edge of the antenna base occurs under the vibration stress and stress concentration. The causes of rubber cracking and metal fatigue fracture may be vibration or abnormal external load.

The hinge on the landing gear door is a very small part, but it’s a significant part. Hinge failures can cause doors to fail to close and, in severe cases, prevent aircraft from landing wheels. The hinge is a welded structure, and the weld is located in the stress sensitive area. This paper analyzes and discusses the failure parts of light trainer aircraft hinge from the stress state, crack characteristics and mechanism modification scheme, so as to provide technical support for ensuring safe flight.

As a typical material of the insert in high-level radioactive waste (HLW) geological disposal canisters, iron-based materials will directly contact with groundwater after the failure of a metallic canister, acting as a chemical barrier to prevent HLW leaking into groundwater. In this paper, anoxic groundwater was simulated by mixing 10 mM NaCl and 2 mM NaHCO3 purged by Ar gas (containing 0.3% CO2) with different added ions (Ca2+, CO32&minus, and SiO32&minus, ) and operation temperatures (25, 40 and 60 &deg, C). An electrochemical measurement, immersion tests and surface characterization were carried out to study the corrosion behavior of pure iron in the simulated groundwater. The effects of Ca2+ on the corrosion behavior of iron is negligible, however, Cl&minus, plays an important role in accelerating the corrosion activity with the increased concentration and temperature. With increased concentrations of CO32&minus, the corrosion resistance of iron is largely improved, which is attributed to the formation of a uniform passivation film. The independent effects of temperature on the corrosion behavior of iron are resulted from the repeated passivation&ndash, dissolution processes in the formation of the passivation film, resulting from the synergistic effects of CO32&minus, /SiO32&minus, and Cl&minus, The formation of ferric silicate is dominant in the passivation film with the addition of SiO32&minus, which effectively protects the iron surface from corrosion.

The classic Fenton reaction, which is driven by iron species, has been widely explored for pollutant degradation, but is strictly limited to acidic conditions. In this work, a copper-based Fenton-like catalyst Cu/Al2O3/g-C3N4 was proposed that achieves high degradation efficiencies for Rhodamine B (Rh B) in a wide range of pH 4.9&ndash, 11.0. The Cu/Al2O3 composite was first prepared via a hydrothermal method followed by a calcination process. The obtained Cu/Al2O3 composite was subsequently stabilized on graphitic carbon nitride (g-C3N4) by the formation of C&minus, O&minus, Cu bonds. The obtained composites were characterized through FT-IR, XRD, TEM, XPS, and N2 adsorption/desorption isotherms, and the immobilized Cu+ was proven to be active sites. The effects of Cu content, g-C3N4 content, H2O2 concentration, and pH on Rh B degradation were systematically investigated. The effect of the catalyst dose was confirmed with a specific reaction rate constant of (5.9 0.07) &times, 10&minus, 9 m&middot, s&minus, 1 and the activation energy was calculated to be 71.0 kJ/mol. In 100 min 96.4% of Rh B (initial concentration 20 mg/L, unadjusted pH (4.9)) was removed in the presence of 1 g/L of catalyst and 10 mM of H2O2 at 25 &deg, C, with an observed reaction rate constant of 6.47 &times, 4 s&minus, 1. High degradation rates are achieved at neutral and alkaline conditions and a low copper leaching (0.55 mg/L) was observed even after four reaction cycles. Hydroxyl radical (HO&middot, ) was identified as the reactive oxygen species by using isopropanol as a radical scavenger and by ESR analysis. HPLC-MS revealed that the degradation of Rh B on Cu/Al2O3/CN composite involves N-de-ethylation, hydroxylation, de-carboxylation, chromophore cleavage, ring opening, and the mineralization process. Based on the results above, a tentative mechanism for the catalytic performance of the Cu/Al2O3/g-C3N4 composite was proposed. In summary, the characteristics of high degradation rate constants, low ion leaching, and the excellent applicability in neutral and alkaline conditions prove the Cu/Al2O3/g-C3N4 composite to be a superior Fenton-like catalyst compared to many conventional ones.

High-index ferroelectric films as (101)-orientated ones exhibit enhanced dielectric responses, piezoelectric responses, and exotic ferroelectric switching behaviors, which are potential candidates for applications in memories and capacitors. However, possible domain patterns and domain wall structures in (101)-oriented ferroelectric thin films are still elusive, which results in difficulties in understanding the origin and further modulating their special properties. In this work, a series of PbTiO3 (PTO) thin films with 35, 50, 60, and 70 nm in thickness were grown on (101)-oriented (LaAlO3)0.29(SrTa1/2Al1/2O3)0.71 (LSAT(101)) substrates by pulsed laser deposition and investigated by both piezoresponse force microscopy (PFM) and (scanning) transmission electron microscopy ((S)TEM). PFM measurements reveal that periodic stripe domains are dominant in 50 nm thick PTO films. Besides stripe domains, a/c domains appear in films with thickness more than 60 nm. A thickness-dependent evolution of piezoresponse a...

The sensor scheduling for energy-efficient target tracking with high performance in wireless sensor networks (WSNs) is a dilemma problem. By analyzing the intrinsic relationship between tracking performance and energy consumption, we cast the scheduling problem of WSN as the optimal policy problem of partially observable Markov decision process (POMDP), and propose a dynamic cluster members scheduling (DCMS) algorithm to solve the tradeoff between tracking performance and energy consumption. First, we exploit an election method, based on the optimal mixed weights of the signal strength and the residual energy of node, to choose the cluster head node. Then, we seem each cluster members an agent, and model the scheduling problem of cluster members by POMDP. At last, a point-based online value iteration algorithm is presented to solve the DCMS to generate the collaboration strategy of sensor cluster members dynamically. The simulation results show that the proposed approach can improve the accuracy of target tracking, decrease the energy consumption of sensor nodes, and prolong the lifetime of sensor networks.

Controlling domain width, orientation, and patterns in oxide ferroelectrics are not only important for fundamental research but also for potential electronic application. Here, a series of PbTiO

Strongly correlated oxides exhibit multiple degrees of freedoms, which can potentially mediate exotic phases with exciting physical properties, such as the polar vortex recently found in ferroelectric oxide films. A polar vortex is stabilized by competition between charge, lattice, and/or orbital degrees of freedom, which displays vortex-ferroelectric phase transitions and emergent chirality, making it a potential candidate for designing information storage and processing devices. Here, by a combination of controlled film growth and aberration-corrected scanning transmission electron microscopy, we obtain nanoscale vortex arrays in [110]-oriented BiFeO

Landing gear system is one of the critical systems of an aircraft and is configured along with the aircraft structure because of its substantial influence on the aircraft structural configuration itself. Landing gear and its attachments are one of the principal structural elements and are useful for aircraft during taxiing, take-off and landing. In this research, A MLG sliding tube from one airline operated A320 aircraft, was returned by user, after a crack indication was discovered at one end of the axle arm. The part had completed about 25,000 cycles since new and 8,000 cycles since overhaul. The mode of crack propagation was intergranular, the crack surface was heavily corroded. A region on the outer diameter encompassing the crack had been blended prior to the receipt. No specific initiation site could be found, it was suspected based on the shape of the crack that initiation occurred from the outer diameter. Deformation was observed on the unblended inner diameter, suggesting that this location suffered a significant impact which imparted residual stress into the component. The Barkhausen noise inspection results support this.

High-index ferroelectric films as (101)-orientated ones exhibit enhanced dielectric responses, piezoelectric responses, and exotic ferroelectric switching behaviors, which are potential candidates for applications in memories and capacitors. However, possible domain patterns and domain wall structures in (101)-oriented ferroelectric thin films are still elusive, which results in difficulties in understanding the origin and further modulating their special properties. In this work, a series of PbTiO

Bayesian reinforcement learning provides an elegant solution to the optimal tradeoff between exploration and exploitation of the uncertainty in learning. Unfortunately, the size of the learning parameters grows exponentially with the problem horizon. In this paper, we propose a novel Monte Carlo tree search for Bayesian reinforcement learning approach using a compact factored representation, to solve the Bayesian reinforcement learning problem online. At first, we exploit a factored representation to describe the states and transition function to reduce the size of learning parameters. Then, we can formulate model-based Bayesian reinforcement learning as a partially observable Markov decision processes. At last, we we apply the partially observable Monte-Carlo planning method as an online solver for Bayesian reinforcement learning. The experimental results show that the proposed approach is an effective way for improving the learning efficiency in large-scale Bayesian reinforcement learning.

Learning and planning in partially bservable Markov decision processes (POMDPs) is computationally intractable in real-time system. In order to address this problem, this paper proposes a belief policy reuse (BPR) method to avoid repeated computation. Firstly, the policy reuse evaluation mechanism based on belief Kullback¨CLeibler divergence is presented as a similarity metric between beliefs in the belief-policy library. If the current belief is similar to any of the past ones, the policy in the belief-policy library is reused. Otherwise, BPR exploits Monte-Carlo particle method to explore a new policy, and stores the new policy with belief in the belief-policy library, so it can be reused in the future. The experimental results show that the proposed approach is an effective way for improving the learning efficiency in large-scale partially observable Markov decision processes.