Browse Articles

Multifunctional complementary field-effect transistors based on MoS2/SWNTs heterostructures

The rapid evolution of devices based on low-dimensional materials such as MoS2 and single-walled carbon nanotubes (SWNTs) has garnered significant interest for high-performance field-effect transistor (FET) applications. We present a multifunctional MoS2/SWNT device exhibiting non-monotonic current modulation with a rectifying ratio of up to 600. The device also demonstrates remarkable optoelectronic memory performance, including fast erasing/writing times (20.1/1.9 ms), a high erasing/writing ratio (104), multilevel data storage, robust retention (10 000 s), and excellent endurance (1000 cycles). Additionally, we demonstrate ternary inverters combining SWNTs FETs with MoS2/SWNTs heterostructure FETs, highlighting their potential in advanced logic applications.

Synergetic effects of nano-boehmite and Y nano-zeolite on catalytic cracking of residue oil

Efficient optical trapping force tuning for cusp-catastrophe autofocusing beams using deep neural networks

Structured light adjusts optical trapping forces through flexible structure design. However, it is challenging to evaluate optical forces on microscopic particles in structured light due to high computational hardware requirements, prolonged computation times, and data inefficiencies associated with solving optical trapping forces using generalized Lorenz–Mie theory. We propose the use of deep neural networks for predicting and tuning the optical trapping force of cusp-catastrophe autofocusing beams on Mie particles. Inputs include beam's structural parameters, laser power, and the size of captured particle, while the output is the optical trapping force. Following iterative training, the neural network achieved a mean square error of 1.5×10−5. Evaluation using 150 sets of test data revealed that 95.3% of the predictions had a relative error of less than 1.8%, indicating a high prediction accuracy. In contrast to traditional computational methods, the neural network model demonstrates a remarkable efficiency improvement—104 times faster in optimizing beams for optical trapping. This advancement demonstrates the advantage of deep learning neural networks for the application of structured light including autofocusing beams in optical tweezers.

Exploring novel solitary wave phenomena in Klein–Gordon equation using $$\phi ^{6}$$ model expansion method

Observation of uncommon elastic wave group velocity in common honeycomb structure and its potential for debonding detection

We report wave propagation with an uncommon negative group velocity (NGV) feature in the common honeycomb structure. Theoretical analysis indicates that the NGV feature arises from the repulsion between skin's localized resonance modes in the same family, influenced by the relative parameters between the core and skin, such as skin thickness. Experimental results show that the NGV feature in honeycomb structure is unlike in isotropic plates, and it only appears in the front half of the hexagon hollow unit, which is surrounded by the honeycomb core. More notably, the NGV feature disappears in the skin–core debonding area and reappears in the intact area, suggesting potential applicability for detecting debonding defects.

Designing of a wide-area power system stabilizer using an exponential distribution optimizer and fuzzy controller considering time delays

Kinetic inductance and non-linearity of MgB2 films at 4K

We report on the fabrication and characterization of superconducting magnesium diboride (MgB2) thin films intended for quantum-limited devices based on non-linear kinetic inductance (NLKI) such as parametric amplifiers with either elevated operating temperatures or expanded frequency ranges. In order to characterize the MgB2 material properties, we have fabricated coplanar waveguide (CPW) transmission lines and microwave resonators using ≈40 nm thick MgB2 films with a measured kinetic inductance of ∼5.5 pH/□ and internal quality factors Qi≈3×104 at 4.2 K. We measure the NLKI in MgB2 by applying a DC bias to a 6 cm long by 4 μm wide CPW transmission line and measuring the resulting phase delay caused by the current dependent NLKI. We also measure the current dependent NLKI through CPW resonators that shift down in frequency with increased power applied through the CPW feedline. Using these measurements, we calculate the characteristic non-linear current parameter, I*, for multiple CPW geometries. We find values for corresponding current density, J*=12–22 MA/cm2, and a ratio of the critical current to the non-linear current parameter, IC/I*=0.14–0.26, similar to or higher than values for other superconductors such as NbTiN and TiN.

Strong immune responses and robust protection following a novel protein in adjuvant tuberculosis vaccine candidate

Abstract BCG remains the only licensed vaccine for tuberculosis (TB), but its efficacy wanes over time. Subunit vaccines, aim to improve BCG immunity and protection, by inducing responses to a few mycobacterial antigens delivered with a specific platform. Since the platform shapes the immune response induced, selecting the right platform has been challenging due to the lack of immune correlates of protection. Recently, the protein-adjuvated subunit vaccine. M72/AS01E, demonstrated 49.7% efficacy in preventing active TB in latently infected adults, indicating that protective immunity through subunit vaccines is possible. In this study we evaluated the immunogenicity and efficacy of the promising mycobacterial antigen PPE15, formulated with five adjuvants developed by the Vaccine Formulation Institute. While all adjuvants were immunogenic, PPE15 with LMQ protected vaccinated mice against an in vivo Mycobacterium tuberculosis challenge, both as a standalone vaccine and as a boost to BCG. Vaccinated mice had enriched lung parenchymal antigen-specific CD4 + CXCR3 + KLRG1− T cells previously associated with TB protection. Heterologous vaccination strategies were also explored by combining intranasal ChAdOx1.PPE15 viral vector, with intramuscular PPE15-LMQ resulting in improved protection compared to individual vaccines. These findings support the progression of this vaccine candidate to the next stages of development.

GaO<i>x</i> interlayer-originated hole traps in SiO2/<i>p</i>-GaN MOS structures and their suppression by low-temperature gate dielectric deposition

In this study, we investigated the impact of SiO2 deposition temperature during plasma-enhanced chemical vapor deposition on the generation of fast hole traps, which cause surface potential pinning, in p-type GaN MOS structures. The thickness of a gallium oxide (GaOx) layer at the SiO2/GaN interface was estimated and correlated with the hole trap generation. The 200 °C-deposited SiO2/GaN MOS structures exhibited a smaller amount of fast hole traps and a thinner GaOx interlayer than the 400 °C-deposited samples. In the 200 °C-deposited samples, annealing at a temperature below 600 °C did not lead to an increase in the fast hole trap and GaOx layer thickness, while the amount of fast traps significantly increased just after 800 °C-annealing in O2 ambient, accompanied by the growth of the GaOx interlayer. These findings suggest that the major origin of fast hole traps in SiO2/GaN MOS structures is a thermally induced defect existing inside a GaOx interlayer and that the low-temperature SiO2 deposition is effective in reducing the fast traps.

Artificial intelligence-enhanced diagnosis of degenerative joint disease using temporomandibular joint panoramic radiography and joint noise data

Manipulation of field-effect transistors by flexoelectric effect

Flexoelectric field-effect transistors (FE-FETs) hold significant potential for applications in biomedical and healthcare sensing fields. While existing piezoelectric FETs sense physiological signals based on pressure or compressive strain, movements such as bending of the elbow or knee joints are more common in physiological activities than external pressure. To address this, this study innovatively introduces FE-FETs that are regulated through the flexoelectric effect induced by bending. In this study, MoS2 with flexoelectric properties is utilized as the channel region. By bending the FE-FETs, the flexoelectric effect is induced, generating a flexoelectric response voltage that alters the Schottky barrier. The results confirm that varying the bending angle of the FE-FETs effectively modulates their transconductance and carrier mobility. Remarkably, the combination of traditional gate voltage and the flexoelectric effect results in a maximum carrier mobility of 49.63 cm2/V · s within a drain voltage range of 0–1 V, which is approximately 10.6 times higher than the carrier mobility of 4.68 cm2/V·s under traditional gate voltage alone. This study provides an effective approach to regulating FE-FETs and expands the possibilities for their application in wearable technology.

The prognostic value of the platelet-to-lymphocyte ratio in multiple myeloma patients treated with a bortezomib-based regimen

Enhanced performance and long-term stability of 2D photodetectors through hexagonal boron nitride encapsulation

Two-dimensional (2D) semiconductor materials, such as molybdenum disulfide (MoS2), demonstrate considerable potential for optoelectronic applications, largely due to their atomic thickness, tunable bandgap, and capacity for heterostructure integration. Nevertheless, the development of 2D photodetectors that can achieve high responsivity, a fast response time, and long-term stability remains a significant challenge. The present study is a systematic investigation of the effects of top and bottom encapsulation with hexagonal boron nitride (h-BN) on the performance and stability of 2D photodetectors. By employing a dry transfer process to fabricate a high-quality h-BN/MoS2/h-BN structure, we provide effective protection against environmental degradation. The encapsulated devices exhibited a responsivity increase of one to two orders of magnitude under 532 nm laser illumination, in comparison to those without encapsulation. Additionally, the rise and decay times were markedly reduced, by approximately two orders of magnitude, from 0.538 and 3.43 ms to 23.1 and 99.6 μs, respectively. Moreover, the devices demonstrated sustained performance over a 60-day storage period, with response times remaining faster than pre-encapsulation levels. This study highlights the potential of h-BN encapsulation for enhancing both the performance and stability of 2D photodetectors, advancing the development of more reliable optoelectronic devices.

Fine tuning enzyme activity assays for monitoring the enzymatic hydrolysis of PET

Impurity-induced step pinning and recovery in MOVPE-grown (100) β-Ga2O3 film

This study focuses on the impact of high-doping impurities (&amp;gt;1018 cm−3) on the morphology of homoepitaxially grown (100) 4° off β-Ga2O3 film, as well as incorporating insights from the Cabrera–Vermilyea model (C–V model). Using atomic force microscopy imaging, we reveal that under low-supersaturation conditions, dopant-induced impurities lead to irregular step formation and growth stalling, inducing the step-bunching formation consistent with C–V model predictions. Conversely, higher supersaturation conditions restore desired step-flow morphology, resembling low-impurity growth states. It is also shown that the step-bunching formed under lower supersaturation conditions and high-impurity concentration might induce unwanted structural defects and compensate the free carriers. These findings underscore the delicate interplay between dopant concentrations, growth morphology, and supersaturation in metalorganic vapor phase epitaxy-grown (100) β-Ga2O3 films, providing a comprehensive understanding of optimizing their electrical properties with respect to power electronics applications.

Health risk assessment via ingestion of disinfection by-products in drinking water

Impact of a RbF post-deposition treatment on the chemical structure of wide-gap CuIn0.1Ga0.9Se2 thin-film solar cell absorber surfaces

A detailed characterization of the impact of a RbF post-deposition treatment (RbF-PDT) on the chemical structure of a wide-gap Cu(In, Ga)Se2 thin-film solar cell absorber surface with a high Ga/(Ga + In) (GGI) ratio of 0.9 is presented. Using synchrotron- and lab-based x-ray photoelectron spectroscopy, as well as x-ray-excited Auger electron spectroscopy, we observe distinct differences to RbF-PDT on absorber surfaces with the common GGI of ∼0.3. In particular, RbF-PDT reduces sodium and oxide content at the surface, while the copper concentration at the surface is not affected. We find no spectral evidence for the formation of a distinct Rb–In–Se surface layer. In addition, we observe that the GGI ratio at the surface is slightly decreased due to a reduction of the Ga and an increase in the In concentration, which may explain the observed improvement in the power conversion efficiency after the PDT (from 6.8% to 7.3%).

Biosynthesized ZnO NPs loaded-electrospun PVA/sodium alginate/glycine nanofibers: synthesis, spinning optimization and antimicrobial activity evaluation

Deposition of plasmonic ITO nanoparticles by near-infrared laser ablation

Compound nanoparticles (NPs) attract attention because of their unique electrical, optical, and catalytic properties. Among them, plasmonic tin-doped indium oxide (ITO) NPs are characterized by transparency in the visible wavelength range and tunable localized surface plasmon resonance (LSPR) in the near-infrared (NIR) range due to high electronic conductivity. To date, they have been usually synthesized by a chemical solution process. However, the chemically synthesized ITO NPs are capped with organic protecting agents, which often block exchange of charge carriers and access of chemical species to the NPs, limiting some applications. In the present study, we propose a method for direct deposition of ITO NPs on a glass or plastic substrate using commercially available ITO-coated glass via NIR laser ablation. The LSPR characteristics of the ITO NPs, thus, prepared were controlled by changing the ablation conditions such as laser power. In addition, the potential applications of the ITO NPs were also investigated through measurements of their refractive index sensitivity and magnetic circular dichroism.

Porous carbons with complex 3D geometries via selective laser sintering of whey powder

Abstract In addition to the inherent limitations of carbons to melt or flow, a vast majority of carbon precursors deforms during carbonisation, with stereolithography of thermoset resins being the preferred technology for 3D printing of carbons. An alternative is now presented with the possibility of using a melting-based technology, selective laser sintering (SLS), to fabricate 3D structures that withstand carbonisation. The key factor that makes this happen is whey powder, a natural, abundant and cheap by-product of the dairy industry. When heating the whey powder with a laser at 180–200 ºC for a few seconds, whey particles sinter, and 3D structures are obtained layer-by-layer. Carbonisation of the sintered whey structures brings about 3D porous carbons with excellent mechanical properties that preserve the SLS printed form albeit an isotropic shrinkage (approx. 23%). Melanoidins are identified as responsible for both the sintering and the thermoset behaviour during carbonisation of the whey powder.