Nanoscale Research Letters最新文献

Twisted van der Waals (t-vdW) heterostructures (HSs), where the electronic and optical properties can be modulated by the interlayer twist angle, have led to the emerging field of “Twistronics.” By precisely controlling the twist angle in stacked vdW materials, researchers are uncovering novel properties and quantum phenomena such as superconductivity, magnetism, and unique charge transport behaviors. This review presents recent advancements in the growth and synthesis of t-vdW HSs focusing mostly on chemical vapor deposition (CVD) and mechanical exfoliation (ME) along with some other techniques including Metal Organic CVD (MOCVD) and molecular beam epitaxy (MBE). We discuss various methods used to control the twist angles, including mechanical stacking and rotational assembly. Each technique’s strengths and limitations are evaluated, particularly in the context of producing high-quality HSs with tunable properties. Special attention is given to optimizing CVD processes to achieve reproducible growth of twisted HSs with precise twist angles. Additionally, this review also explores the theoretical and experimental insights into the influence of twist angles on physical, optical, and electronic properties of vdW HSs. By examining the progress and challenges in this field, we highlight future directions and the potential of t-vdW HSs in advancing next-generation opto-electronic and quantum devices.

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Inefficient thermal transmission in heat exchangers requires creative solutions. Ternary hybrid nanofluids have evolved to offer improved thermal efficiency compared to standard nanofluids. The current study involves a ternary hybrid nanofluid of copper oxide (CuO), titanium dioxide (TiO₂), and silver (Ag) nanoparticles suspended in a base fluid of water-ethylene glycol (50–50%) (H₂O–C₂H₆O₂) to enhance thermal efficiency. This comprehensive analysis aims to provide insights into the heat transfer behaviour of a ternary hybrid nanofluid flow through a porous medium, considering the magnetic field effects in the momentum equation, exothermic/endothermic (Thermochemical) reactions in the energy equation, and activation energy in the concentration equation, respectively, on a rotating stretching sheet. Partial differential equations (PDEs) govern the flow problem. PDEs are converted to Ordinary differential equations (ODEs) using a suitable similarity transformation to aid solution. The linearised equations are solved numerically using MATLAB’s “bvp4c” boundary value problem solver. Variations in the velocity, temperature and concentration profiles due to various parameters are presented graphically. The results show that increasing M and Fr values increases (theta ) profile by 1.2% and 0.85% respectively. Whereas the overall increase in the heat transfer is 6.65% and mass transfer is 1.86%, making this a substantial contribution to our work. This research will benefit manufacturers of cosmetics, hydraulic fluids, and fibreglass. Furthermore, the findings are supported by the available literature in specific instances, and they exhibit a strong concordance.

The intestine is an important organ in radiotherapy of the abdominal region, and radiation-induced intestinal injury (RIII) is an undesirable biological response to radiotherapy. Radiotherapy is known to induce oxidative stress associated with the generation of reactive oxygen species (ROS), which in turn plays an important role in RIII. However, these effects cannot be detected or predicted early using conventional imaging techniques such as computed tomography and magnetic resonance imaging (MRI). In this study, an intestinal redox imaging method using dynamic nuclear polarization (DNP) MRI and carbamoyl PROXYL (CmP) was designed. The probe was prepared in a solution of increased viscosity of the CmP solution that is not affected by peristalsis. This redox imaging method enabled noninvasive redox imaging of the intestine and detection of RIII at an early stage of progression. Our findings suggest that redox imaging can aid in monitoring early metabolic changes that occur during the pathogenesis of this condition.

The inherent catalytic efficiency of Fe₃O₄ nanoparticles (Fe₃O₄ NPs) for water splitting is unsatisfactory owing to its limited electronic conductivity and inadequate active sites necessary for both oxygen and hydrogen evolution processes (OER and HER). These issues have prompted the investigation of diverse approaches for Fe₃O₄ NPs, including doping with transition metals. Herein, the Co-doped Fe₃O₄ NPs were loaded on Ni-foam using a microwave-assisted method, and characterized by various analytical techniques. The electrochemical investigations demonstrated that Co-doped Fe₃O₄ NPs exhibit exceptional OER and HER performance, with minimal overpotentials of 146 mV and 210 mV at a current density of 10 mA/cm², in contrast to Fe₃O₄ NPs, which showed overpotentials of 278 mV and 245 mV at the same current density. Theoretical investigations indicated that Co-doping substantially altered the electronic structure and optimised the active sites of Fe₃O₄ NPs, hence enhancing overall catalytic efficiency. This study presents an innovative approach for the synthesis of highly efficient, economical electrocatalysts for water splitting, with potential applications in clean energy generation and sustainable hydrogen production.

The present study is focused on the biosynthesis of silver nanoparticles derived from Sapindus mukorossi pericarp extract. Silver nanoparticles were synthesized successfully by employing biological methods. In the present research, silver nitrate was used as a precursor and Sapindus mukorossi pericarp extract was used as a reducing agent for synthesis. The obtained nanoparticles were characterized using UV–Vis spectroscopy, X-ray diffraction (XRD), Fourier transform electron microscopy (FTIR) and High-resolution transmission electron microscopy (HR-TEM). The UV–Vis spectra and visual observation showed that the color of pericarp extract of S. mukorossi turned from golden yellow to dark brown after the addition of AgNO₃ precursor and showed the highest absorption peak at 410 nm. In addition, XRD pattern revealed the face-centered cubic structure of silver nanoparticles. The FTIR measurements confirmed the presence of different functional groups within the extract that were directly involved in the reduction and stability of biosynthesized silver nanoparticles. HR-TEM images revealed the particles to be nearly spherical with a few irregular shapes and particles size ranging from 5 to 50 nm. The study highlights the antimicrobial activity and MIC of biosynthesized nanoparticles that were tested against gram negative bacterium viz., Pseudomonas aeruginosa, Escherichia coli and gram-positive bacterium Staphylococcus aureus, Bacillus subtilis. The results confirmed that the nanoparticles showed better antimicrobial potential against all the tested microorganisms as compared to control. The antioxidant potential of aqueous extract and biosynthesized silver nanoparticles was evaluated using DPPH (2,2-diphenyl-1-picrylhydrazyl) method and revealed that S.mukorossi nanoparticles exhibit significant antioxidant activity.

Molecular electronics has received considerable attention because molecular devices can provide several unique properties, such as giant magnetoresistance, a large Seebeck effect, and nonvolatile switching properties. These unique properties, including enhanced performances, have been observed in molecular nanoscale devices. Therefore, the miniaturization of molecular devices is a key issue for their practical use as well as for the development of fundamental science. In a previous study, we proposed a new nanojunction fabrication method using thin-film edges and successfully fabricated Ni₇₈Fe₂₂/2,7-dioctyl[1]benzothieno[3,2-b][1]benzothiophene (C8-BTBT)/Ni₇₈Fe₂₂ nanojunctions with a junction area of 42 × 42 nm². In this study, toward the realization of a smaller junction area, we fabricate Ni₇₈Fe₂₂/C8-BTBT/Ni₇₈Fe₂₂ nanojunctions using our advanced method. As electrodes in our nanojunctions, 7-nm-thick Ni₇₈Fe₂₂ thin films sandwiched between low-softening-point glasses can be fabricated using the thermal pressing technique. The area of the nanojunctions is determined from the thickness of the Ni₇₈Fe₂₂ thin film. Using these electrodes, we have successfully fabricated Ni₇₈Fe₂₂/C8-BTBT/Ni₇₈Fe₂₂ nanojunctions with a junction area of 7 × 7 nm², which is the minimum value ever reported for edge-to-edge nanodevices, and observed electrical conduction through C8-BTBT molecules in the devices. Our study provides a novel nanofabrication technique and opens new opportunities for research in molecular nanoelectronics.

Green synthesis approaches to produce silver nanoparticles (AgNPs) have gained considerable attention recently due to their eco-friendliness and diverse applications in biotechnology, healthcare and environmental management. The present study explores the biogenic synthesis of AgNPs using aqueous extracts of Cinchona calisaya Wedd. and Cinchona pubescens Vahl. The research focuses on the physicochemical characterisation of AgNPs using several analytical techniques such as UV-visible spectroscopy, transmission electron microscopy (TEM), dynamic light scattering, Fourier transform infrared spectroscopy, powder X-ray diffraction (PXRD), and energy dispersive X-ray spectroscopy. The obtained nanoparticles exhibited diverse sizes ranging from 23 ± 3 to 50 ± 9 nm, with a spherical shape observed on TEM images and with elemental composition containing Ag, N, C, O, etc. FTIR data indicated that chemicals containing carboxylic, hydroxyl, alkanes and carbonyl groups are bonded on the surface of AgNPs, while PXRD data indicated that the AgNPs were crystalline. Furthermore, a deep evaluation of the biological activities of the AgNPs was conducted. AgNPs exhibited moderate antioxidant, antibacterial and antifungal activities. Additionally, the produced AgNPs exhibited a dose-dependent potency for environmentally friendly vector control (larvicidal action) at the concentrations ranging from 200 to 400 ppm. The total phenolic content of C. calisaya and C. pubescens extracts and AgNPs was between 288.73 ± 20.42 mg/100 mL and 464.47 ± 16.44 mg/100 mL. This comprehensive investigation provides valuable insights into the potential of C. ledgeriana and C. pubescens leaf extracts as reducing and capping agents for AgNPs synthesis. The outcomes of this study have far-reaching implications for green nanotechnology, eco-friendly materials science and biomedicine. The diverse properties of AgNPs facilitate innovative healthcare and environmental sustainability applications, highlighting their potential to tackle significant global issues.

To improve charge extraction and address UV-induced degradation in perovskite solar cells, we propose and numerically evaluate a TiO₂/SnO₂ bilayer electron transport layer (ETL) architecture. Using physics-based simulation, we systematically analyze the influence of individual and combined ETL thicknesses on key parameters. The results identify an optimal configuration of 100 nm TiO₂ and 20 nm SnO₂, which minimizes interfacial recombination and enhances electron transport. Furthermore, CH₃NH₃SnI₃ is employed as a lead-free absorber layer. Simulation results demonstrate a notable efficiency improvement upto 20.80%. The experimental results verified that the bi-layer Sn-based perovskite can achieve a conversion efficiency of 10.3%. This study highlights the potential of simulation-guided design in optimizing multilayer ETL structures and advancing environmentally friendly, high-efficiency perovskite photovoltaics.

Micronutrients, including vitamins and minerals, are essential for maintaining normal health. Micronutrient deficiency can lead to various health complications. Assessing micronutrient levels is crucial, as early and routine micronutrient assessment and supplementation can help prevent deficiencies. Current assessment methods, such as Immunoassays, high-performance liquid chromatography (HPLC)-ultra-violet (UV) spectroscopy/fluorescence detection (FLD), liquid chromatography coupled with mass spectrometry (LC–MS), and similar techniques, are sophisticated, expensive, time-consuming, and require trained professionals. These limitations have prompted the development of point-of-care (POC) micronutrient screening devices that are simple, quick, reliable, and cost-effective. Electrochemical biosensors are one of the most promising analytical platforms for healthcare and other applications. This review focuses on the recent advances in electrochemical biosensors for vitamin sensing. It covers various types of electrochemical biosensors, including amperometric, potentiometric, and impedimetric biosensors, and discusses challenges associated with biosensors for potential use in healthcare as a routine vitamin assessment method.