Browse Articles

Development of a model for detection and analysis of inclusions in tomographic images of iron castings using decision trees

High-strength elastomer separator for high-current-density-charging lithium metal batteries

Utilizing lithium metal as an anode in batteries has been expected to replace conventional lithium-ion batteries. However, the mechanical properties and electrochemical performance of current separators do not meet the requirements for practical applications of lithium metal batteries (LMBs). Here, we report an elastomer separator with an interconnected structure of plastic-crystal-embedded and garnet-conductor-regulated thermoplastic polystyrene-b-poly(ethylene-r-butylene)-b-polystyrene elastomer integrated with the polyethylene matrix. The 14-micron-thick elastomer separators show a combination of excellent elongation of ∼115.2% and sufficiently high tensile strength of ∼56 MPa. The elastomer separators accommodate volume changes and block dendrites for high-current-density cycling of LMBs. As a demonstration, the elastomer separators enable stable operation of LMBs under stringent conditions, a practical high loading of 18 mg cm−2 LiNi0.8Co0.1Mn0.1O2 (NCM811) cathode at an extremely high charging/discharging current density of 1.8 mA cm−2, delivering a high reversible capacity of 164 mAh g−1 and capacity retention of 88% after 140 cycles.

Purification of arsenic-contaminated drinking water by Fe-Al-CO3 layered double hydroxide derived from secondary aluminum dross: adsorption and stabilization studies

Spin transfer torque switching in double magnetic tunnel junctions based on dual MgO layers

We report fabrication and characterization of double magnetic tunnel junction (DMTJ) magneto-resistive random access memory cells that exhibit characteristic about 2X reduction of switching current compared to single reference layer junctions, but maintain high tunneling magnetoresistance ratio exceeding 120 %, high coercive fields of the free layer of more than 2 kOe for 65 nm cells, and magnetically stable reference layers with pinning fields above 6 kOe. Switching analysis performed for two different relative magnetization orientations of the reference layers shows that the net switching current is the result of combined spin transfer torque effects of the individual reference layers, with tunneling and spin-valve-like contributions adding constructively. Our work shows that efficient reduction of switching current can be achieved in double magnetic tunnel junctions with dual MgO layers where one of the layers has significantly lower resistance-area product to enable high magnetoresistance ratio.

Bending behavior and influence parameter optimization of connection joints of disc-buckle type formwork support

Multi-functional terahertz nano-metasurface for beam-splitting and nonlinear resonance frequency shifting

The emergence of terahertz (THz) nanoscale resonance metasurface devices represents an innovative method for modulating THz waves by utilizing the intense, high-frequency alternating electric field in THz radiation. However, compared to traditional modulation methods that employ electrical, optical, and other techniques, the potential of these devices still necessitates further exploration. In this work, we achieved THz beam-splitting and field-induced nonlinear frequency shifting functions within a single THz nano-metasurface device. The device consists of single split-ring resonators (s-SRRs) with a nanogap on GaAs substrate. The pattern design based on the Pancharatnam–Berry (P-B) phase principle can split the incident wave into three beams. Meanwhile, its frequency shifting capability, which varies with the E-field, has been thoroughly investigated. The device performance was experimentally evaluated by an angle-resolved THz time-domain spectroscopy (THz-TDS) system and a strong-field THz-TDS system. This device could serve as a promising research platform for integrating THz with nano-optics and holds the potential for ultrafast modulation, offering application prospects in radar, wireless communication, and electromagnetic protection.

High throughput method for simultaneous screening of membrane permeability and toxicity for discovery of new cryoprotective agents

Enhanced perovskite crystallinity via short-term ultraviolet irradiation

Despite the recent rapid development in the organic–inorganic halide perovskite solar cells (PSCs), the crystalline stability of the perovskite (PVK) material, particularly of the MAPbI3, remains a significant impediment to PSC applications. We proposed that short-term ultraviolet (UV) irradiation under air conditions can stabilize the PVK phase and increases the film crystallinity. Detailed investigations indicated that the electrons can be released from the bridging hydroxyls (OHB) bonds under UV irradiation to generate a small amount of active oxygen (O2−) on the TiO2 film surface, forming stable Pb–O bonds and α phase PVK. A 25% increases in photovoltaic conversion efficiency with a considerable stability, and the device maintains over 90% efficiency after 400 h of storage in N2. This study provides a simple and effective method to produce efficient and stable PSC devices at low cost.

Research on spatial prediction technology for mitigating tunnel inrush disasters under complex geological conditions in China’s Hengduan Mountain Range

Boosting thermoelectric properties of n-type PbS across a broad temperature range through doping with trace amounts of InBi

Lead sulfide (PbS) is a promising thermoelectric material due to its high availability, thermal stability, and cost-efficiency, with research predominantly aiming to enhance its carrier concentration through heavy doping for optimal ZT values at high temperatures. However, this approach often results in suboptimal performance at ambient temperature, significantly constraining its applicability in thermoelectric cooling technologies. In this work, the carrier concentration of n-type PbS is optimized by incorporating trace amounts of InBi. Due to the low carrier concentration, PbS retains a high Seebeck coefficient and carrier mobility, resulting in a high average power factor (PFave) of 15.4 μW·cm−1·K−2 within the temperature range from 300 to 773 K. In addition, the introduction of In/Bi interstitial atoms and dislocation defects enhances phonon scattering, effectively reducing the lattice thermal conductivity of PbS. The peak ZT value of Pb0.999(InBi)0.001S at 773 K reaches ∼1.0, while an average ZT value (ZTave) of ∼0.6 is achieved between 300 and 773 K in Pb0.9995(InBi)0.0005S. This study demonstrates that trace element doping is an effective strategy for optimizing the thermoelectric performance of PbS across a wide temperature range, which is vital in the thermoelectric power generation and refrigeration application.

Dentoskeletal effects of aesthetic and conventional twin block appliances in the treatment of skeletal class II malocclusion: a randomized controlled trial

Superconducting flip-chip devices using indium microspheres on Au-passivated Nb or NbN as under-bump metallization layer

Superconducting flip-chip interconnects are crucial for the three-dimensional integration of superconducting circuits in sensing and quantum technology applications. We demonstrate a simplified approach for a superconducting flip-chip device using commercially available indium microspheres and an in-house-built transfer stage for bonding two chips patterned with superconducting thin films. We use a gold-passivated niobium or niobium nitride layer as an under-bump metallization (UBM) layer between an aluminum-based superconducting wiring layer and the indium interconnect. At millikelvin temperatures, our flip-chip assembly can transport a supercurrent with tens of milliamperes, limited by the smallest geometric feature size and critical current density of the UBM layer and not by the indium interconnect. We show that the pressed indium interconnect itself can carry a supercurrent exceeding 1 A due to its large size of about 500 μm diameter. Our flip-chip assembly does require neither electroplating nor patterning of indium. The assembly process does not need a flip-chip bonder and can be realized with a transfer stage using a top chip with transparency or through-vias for alignment. These flip-chip devices can be utilized in applications that require few superconducting interconnects carrying large currents at millikelvin temperatures.

Resurgence of common respiratory viruses and mycoplasma pneumoniae after ending the zero-COVID policy in Shanghai

A synaptic transistor with a stacked layer of SiNx and SiO2 deposited from hexamethyldisiloxane/O2

Herein, we employed inductively coupled plasma enhanced chemical vapor deposition using a hexamethyldisiloxane/O2 precursor to deposit SiO2 with electrical double layer capacitance on SiNx forming SiO2/SiNx stacked films as a dielectric layer, achieving high-performance synaptic transistors. The effect of O2 concentration during SiO2 deposition on the transistor performance was investigated. The results of Fourier transform infrared spectroscopy and x-ray photoemission spectroscopy confirm that increasing O2 concentration during deposition boosts the amounts of protons moving between the bridging oxygen in the Si–O–Si network, improving the electrical double layer capacitance of SiO2. Furthermore, SiNx in the stacked structure exhibits a higher relative permittivity than SiO2, resulting in a more concentrated electric field within the SiO2 layer, facilitating proton ionization. SiO2/SiNx stacked film with SiO2 deposited at the oxygen flow rate of 150  sccm exhibited the maximum capacitance of 2.87 μF/cm2 at 4 Hz. The transistor with SiO2 deposited at the oxygen flow rate of 150  sccm achieved the maximum paired pulse facilitation index of 132.9% and the maximum A50/A1 index of 155.4%. This work demonstrates that SiO2 deposited via inductively coupled plasma enhanced chemical vapor deposition using a hexamethyldisiloxane/O2 precursor for application potential in artificial neuromorphic computing.

Temperature dynamics and mechanical properties analysis of carbon fiber epoxy composites radiated by nuclear explosion simulated light source

Geometric effects in the measurement of the remanent ferroelectric polarization at the nanoscale

A resurgence of research on ferroelectric materials has recently occurred due to their potential to enhance the performance of memory and logic. For the design and commercialization of such technologies, it is important to understand the physical behavior of ferroelectrics and the interplay with device size, geometry, and fabrication processes. Here, we report a study of geometric factors that can influence the measurement of the remanent ferroelectric polarization, an important measurement for understanding wakeup, retention, and endurance in ferroelectric technologies. The areal size scaling of W/Hf0.5Zr0.5O2/W capacitors is compared in two typical structures: an island top electrode with a continuous ferroelectric layer and an island top electrode/ferroelectric layer (etched ferroelectric layer). Error in the evaluation of the switched area leads to anomalous scaling trends and increasing apparent remanent polarization as capacitor sizes decrease, most strongly in continuous ferroelectric layer capacitors. Using TEM and electric field simulations, this is attributed to two effects: a processing artifact from ion milling that creates a foot on the top electrode and a fringe electric field penetrating outside of the capacitor area. With the correction of the switching area, the 2Pr for both samples agree (∼32 μC cm−2) and is invariant in the capacitor sizes used (down to 400 nm diameter). Our work demonstrates that the determination of the actual capacitor structure and local electric field is needed to evaluate the intrinsic ferroelectric behavior at the nanoscale.

Incorporation of recombinant proteins into extracellular vesicles by Lactococcus cremoris

Abstract Extracellular vesicles (EVs) are nanosized lipid bilayer particles released by various cellular organisms that carry an array of bioactive molecules. EVs have diagnostic potential, as they play a role in intercellular interspecies communication, and could be applied in drug delivery. In contrast to mammalian cell-derived EVs, the study of EVs from bacteria, particularly Gram-positive bacteria, received less research attention. This study aimed to investigate the production of EVs by lactic acid bacterium Lactococcus cremoris NZ9000 and to examine the impact of recombinant protein expression on their formation and protein content. Four different recombinant proteins were expressed in L. cremoris NZ9000, in different forms of expression and combinations, and the produced EVs were isolated using the standard ultracentrifugation method. The presence of vesicular structures (50–200 nm) in the samples was confirmed by transmission electron microscopy and by flow cytometry using membrane-specific stain. Mass spectrometry analyses confirmed the presence of recombinant proteins in the EVs fraction, with amounts ranging from 13.17 to 100%, highlighting their significant incorporation into the vesicles, together with intrinsic L. cremoris NZ9000 proteins that were either more abundant in the cytoplasm (ribosomal proteins, metabolic enzymes) or present in the membrane. The presence of the most abundant lactococcal proteins in EVs fraction suggests that protein cargo-loading of EVs in L. cremoris NZ9000 is not regulated. However, our data suggests that L. cremoris NZ9000 genetically engineered to express recombinant proteins can produce EVs containing these proteins in scalable manner. As L. cremoris NZ9000 is considered safe bacterium, EVs from L. cremoris NZ9000 could have several advantages over EVs from other bacteria, implying possible biotechnological applications, e.g. in therapeutic protein delivery.

Magnon signatures of multidimensional reconfigurations in multilayer square artificial spin ices

We present an all-electrical, broadband spin-wave spectroscopy study of three-dimensional square artificial spin ices composed of dipolarly coupled ferromagnetic layers of varying thicknesses separated by a non-magnetic spacer. Our experiments, in the saturated regime, reveal that the spin-wave spectra exhibit a strong dependence on both the angle of the applied magnetic field and the geometrical aspect ratio of the ferromagnetic layers. Micromagnetic simulations and analytical calculations, utilizing the Smit–Beljers formalism, demonstrate good agreement with our experimental findings. In the magnetic switching regime, the spin-wave spectra indicate an antiparallel alignment between the two ferromagnetic layers. This configuration is highly sensitive to the field angle, suggesting the presence of multidimensional reconfigurations within the multilayer artificial spin ice. Furthermore, employing a minor loop field protocol, we show that the spin-wave modes associated with the antiparallel alignment remain reproducible, even after 100 minor loop cycles, providing intriguing possibilities for magnonic engineering.

A combinatory approach of non-chain ring and henon map for image encryption application

Design of spike-timing-dependent plasticity synapses based on CoPt-SOT device and its application in all-spin spiking neural network

Spintronic could be used to simulate synapses or neurons due to its multistate storage characteristics. In this work, a reliable design of all-spin spiking neural networks (SNN) based on spin–orbit torque (SOT) devices has been proposed in A1 CoPt single layer. The CoPt-SOT devices exhibited field-free SOT switching, and the magnetization reversal mechanism was inferred to be a combination of domain nucleation and domain-wall propagation as observed through magneto-optical Kerr microscopy images. Moreover, the current-induced SOT switching process of the device exhibited stable multistate magnetic switching behavior, which can be controlled by varying the amplitude and pulse width of the current pulse. Meanwhile, the spike-timing-dependent plasticity (STDP) curve was inverted when the SOT switching polarity was reversed by different magnetic fields, and the change in anomalous Hall resistances (ΔRH) in the STDP curve was linearly related to the SOT switching ratio. In addition, at the zero magnetic field, we constructed an all-spin SNN using STDP synapses and leaky integrate-and-fire neurons of CoPt-SOT devices. The handwritten digits recognition rate of this all-spin SNN network was 89.9%. These results substantiate that the CoPt single layer represents a promising hardware solution for high-performance neuromorphic computing, with applicability in the domain of SNN.