We investigate phase-coherent quantum transport in nanoscale Al-Bi2Se3-Al nanoribbon Josephson junctions by combining normal-state conductance spectroscopy with a junction-length-dependent study of Josephson transport. Differential conductance maps versus bias and gate voltage reveal Fabry-Pérot interference, whose periodicity matches the nanoribbon width, consistent with transverse quantization and quasi-ballistic surface-state trajectories in 430 nm wide devices. A systematic investigation of the characteristic voltage I c R n as a function of junction length L exhibits a clear plateau for L ≤ 500 nm, indicative of a short ballistic contribution to the Josephson transport, and decreases for longer junctions as diffusive transport dominates. Together, Fabry-Pérot interference and Josephson transport measurements provide complementary, channel-selective evidence for quasi-ballistic surface-state transport persisting over several hundred nanometers in hybrid topological insulator nanostructures. These results demonstrate the potential of Bi2Se3 nanoribbon Josephson junctions as a nanoscale platform for phase-coherent superconducting electronics, topological quantum computing architectures, and topological spintronic devices.

We investigate phase-coherent quantum transport in nanoscale Al-Bi2Se3-Al nanoribbon Josephson junctions by combining normal-state conductance spectroscopy with a junction-length-dependent study of Josephson transport. Differential conductance maps versus bias and gate voltage reveal Fabry-Perot interference, whose periodicity matches the nanoribbon width, consistent with transverse quantization and quasi-ballistic surface-state trajectories in 430 nm wide devices. A systematic investigation of the characteristic voltage I c R n as a function of junction length L exhibits a clear plateau for L <= 500 nm, indicative of a short ballistic contribution to the Josephson transport, and decreases for longer junctions as diffusive transport dominates. Together, Fabry-Perot interference and Josephson transport measurements provide complementary, channel-selective evidence for quasi-ballistic surface-state transport persisting over several hundred nanometers in hybrid topological insulator nanostructures. These results demonstrate the potential of Bi2Se3 nanoribbon Josephson junctions as a nanoscale platform for phase-coherent superconducting electronics, topological quantum computing architectures, and topological spintronic devices.

We study quantum interference effects in hybrid devices consisting of topological insulator Bi2Se3 nanoribbons contacted by two Al electrodes. Conductance oscillations as a function of bias and gate voltage reveal a distinct crossover in transport behavior. For junctions narrower than 500 nm, the oscillation periodicity matches the junction width, consistent with Fabry-Perot interference and quasi-ballistic transport over nearly micrometer scales. In contrast, wider devices exhibit irregular, quasi-periodic oscillations that we attribute to universal conductance fluctuations, signaling a transition to diffusive transport as the junction width becomes too large for transverse quantization to govern the interference pattern. Complementary Josephson current measurements confirm that ballistic modes persist over long distances, far beyond what magnetotransport suggests. These findings highlight the sensitivity of Fabry-Perot interference and Josephson current probes to ballistic transport channels.

In recent years much progress has been made in realizing topological insulator (TI) nanostructures where the reduced dimensions should help to diminish the contributions from bulk carriers and enhance quantum confinement. Though nm thick 3D-TI nanoribbons exhibiting topological properties are still difficult to reproducibly synthesize. Here we demonstrate the growth of ultrathin Bi2Se3 nanoribbons by a simple catalyst-free physical-vapour deposition, where the tuning of the material evaporation time plays a crucial role in determining the ultimate thickness of the nanoribbons. Magnetotransport and Hall effect measurements show that at thicknesses close to 10 nm the transport features are affected by Altshuler-Aronov-Spivak like coherent orbits at low magnetic fields, while Shubnikov-de Haas oscillations take over at high fields. The observed phenomena originate from the topological surface states and dominate the nanoribbon transport. Ultrathin nanoribbons also show pronounced conductance oscillations as a function of gate voltage, that can be attributed to ballistic transport and quantized sub-bands. The results highlight the importance of material growth to exploit the unique properties of topological surface states, establishing 3D-TI nanoribbons as a promising platform for a variety of novel applications.

In recent years much progress has been made in realizing topological insulator (TI) nanostructures where the reduced dimensions should help to diminish the contributions from bulk carriers and enhance quantum confinement. Though nm thick 3D-TI nanoribbons exhibiting topological properties are still difficult to reproducibly synthesize. Here we demonstrate the growth of ultrathin [Formula: see text] nanoribbons by a simple catalyst-free physical-vapour deposition, where the tuning of the material evaporation time plays a crucial role in determining the ultimate thickness of the nanoribbons. Magnetotransport and Hall effect measurements show that at thicknesses close to 10 nm the transport features are affected by Altshuler-Aronov-Spivak like coherent orbits at low magnetic fields, while Shubnikov-de Haas oscillations take over at high fields. The observed phenomena originate from the topological surface states and dominate the nanoribbon transport. Ultrathin nanoribbons also show pronounced conductance oscillations as a function of gate voltage, that can be attributed to ballistic transport and quantized sub-bands. The results highlight the importance of material growth to exploit the unique properties of topological surface states, establishing 3D-TI nanoribbons as a promising platform for a variety of novel applications.

Room-temperature thermoelectric properties of heterostructures fabricated by direct physical vapor deposition of Bi2Se3 nanostructures on n-type nitrogen-doped multiwalled carbon nanotubes (nMWCNTs) were studied as a function of nMWCNT wt% and compared with the properties of similar heterostructures fabricated using conventional undoped MWCNTs having p-type conductance (pMWCNTs). Bi2Se3-nMWCNT heterostructures exhibited n-type conductance and showed maximal Seebeck coefficient values of-120 +/- 10 mu V/K and power factor of- 14 +/- 1 mu W/mK2 at nMWCNT concentration below 3 wt%, which exceeded previously reported Seebeck coefficient and power factor of Bi2Se3-pMWCNT heterostructures by a factor 2 and 3 respectively. This effect was found to be related to the contribution of a topologically protected 2D interface conducting channel to the total Seebeck coefficient of the Bi2Se3-nMWCNT heterostructures in addition to contributions of nMWCNT and Bi2Se3 components. Formation of the topologically protected 2D conducting channel at the interface between Bi2Se3 and nMWCNTs was revealed as a result of the analysis of magnetotransport measurements of Bi2Se3- nMWCNT heterostructures and their individual components in the temperature range 2-300 K and confirmed by the observation of a well-pronounced weak anti-localization cusp in the temperature range of 2 - 10 K. Encapsulation of the Bi2Se3-nMWCNT heterostructures in polyvinyl alcohol preserved the structure of the samples and resulted in the increase of their power factor by 2-30 %, which was attributed to the filtering-out of lower energy charge carriers via additional potential barriers introduced in the conduction band of heterostructure components due to the presence of polymer.

Novel core shell nanofibers, their magneto-optical properties, and degradation of APCs.

Room-temperature thermoelectric properties of heterostructures prepared by direct physical vapor deposition of Bi2Se3 nanostructures on carbon fullerenes (C60)-multiwalled carbon nanotubes (MWCNT) substrates were studied in relation to the C60/MWCNT wt % ratio in the substrate and compared with the properties of similar heterostructures fabricated using bare untreated p-type MWCNTs and nitrogen-doped n-type MWCNTs (nMWCNTs). It is found that Bi2Se3-C60-MWCNT heterostructures exhibit n-type conductance when the total wt % of the C60-MWCNT component does not exceed 10 wt %, and at optimal C60/MWCNT ratios the maximal power factor of similar to 58 mu W/mK2 is reached, which exceeds previously reported maximal power factor values exhibited by Bi2Se3-MWCNT and Bi2Se3-nMWCNT heterostructures, as well as by C60-based hybrid thermoelectric materials, by factors of similar to 11, similar to 4, and similar to 2, respectively. This effect was attributed to the cluster-like growth mechanism of Bi2Se3 on C60-MWCNT substrates different from that on bare MWCNTs, which was supported by the magnetoresistance studies of the Bi2Se3-C60-MWCNT heterostructures in the 2-300 K temperature range, and to the charge transfer between the Bi2Se3 and C60 molecules, resulting in the formation of a Bi2Se3-dominated heterostructure with enhanced Seebeck coefficient, reaching similar to-110 to -150 mu V/K and electrical resistivity not exceeding 1 m Omegam for optimal C60/MWCNT ratios, which is similar to or lower than that of Bi2Se3-MWCNT and Bi2Se3-nMWCNT heterostructures. In addition, bending tests performed for Bi2Se3-C60-MWCNT heterostructures with the best power factor showed that these structures are stable during 100 consecutive bending cycles down to a 4 mm radius. This work opens the path for significant improvement of thermoelectrical properties of topological insulator-carbon allotrope heterostructures by tuning their charge transport mechanism using different types and concentrations of carbon allotropes and for their application in flexible thermoelectrics.

In recent years much progress has been made in realizing topological insulator (TI) nanostructures where the reduced dimensions should help to diminish the contributions from bulk carriers and enhance quantum confinement. Though nm thick 3D-TI nanoribbons exhibiting topological properties are still difficult to reproducibly synthesize. Here we demonstrate the growth of ultrathin $${\mathbf {{{Bi}_{2}}}\mathbf {{Se}_{3}}}$$ nanoribbons by a simple catalyst-free physical-vapour deposition, where the tuning of the material evaporation time plays a crucial role in determining the ultimate thickness of the nanoribbons. Magnetotransport and Hall effect measurements show that at thicknesses close to 10 nm the transport features are affected by Altshuler-Aronov-Spivak like coherent orbits at low magnetic fields, while Shubnikov-de Haas oscillations take over at high fields. The observed phenomena originate from the topological surface states and dominate the nanoribbon transport. Ultrathin nanoribbons also show pronounced conductance oscillations as a function of gate voltage, that can be attributed to ballistic transport and quantized sub-bands. The results highlight the importance of material growth to exploit the unique properties of topological surface states, establishing 3D-TI nanoribbons as a promising platform for a variety of novel applications.

Coaxial electrospinning is a facile and versatile method for the fabrication of core-shell metal oxides for environmental applications. The use of core-shell metal oxide nanofibers with a magnetic core and photocatalytic shell is a new approach for the photocatalytic degradation of active pharmaceutical compounds (APCs) in water and the removal of photocatalysts by a magnetic field. In the present work, we report the fabrication and characterization of novel Fe3O4-Fe2NiO4/NiO core-shell nanofibers with advanced structural, optical, magnetic and photocatalytic properties via co-axial electrospinning. The aim of this work is to investigate the photocatalytic degradation of acetaminophen by the novel metal oxide core-shell nanofibers with different structural properties. The core-shell nanofibers were fabricated using constant core solution parameters (PAN 7.55% w/w and Fe nitrate 5.5% w/w) and variable shell solution parameters (PVP 11.4-11.1% w/w and Ni acetate 5.29-8.51% w/w). The phase transition of Fe3O4 → Fe2NiO4 was observed in the core. The Fe3O4-Fe2NiO4/NiO nanofibers exhibit a high optical absorption in the visible range (band gaps of 2 eV and 2.2 eV), significant magnetization (15 A m2 kg-1) and high efficiency for the degradation of methylene blue (80%) and acetaminophen (45%). The photocatalytic properties of the Fe3O4-Fe2NiO4/NiO nanofibers significantly depended on their core and shell chemical composition. The formation of spinel Fe2NiO4 in the core was one of the factors that limited the photocatalytic performance of the core-shell nanofibers. Thus, their photocatalytic performance could be improved by adjusting the core and shell fabrication parameters. The advanced properties of the Fe3O4-Fe2NiO4/NiO core-shell nanofibers highlight their applications for the efficient degradation of active pharmaceutical compounds in water resources.

This study utilized atomic force microscopy (AFM) to analyze intraoperative frozen histology samples from 26 patients with non-small cell lung cancer tissue, specifically adenocarcinoma and squamous cell carcinoma. Clear and measurable structural differences were identified between tumor cell regions and stroma of the two subtypes. Nuclear region morphologies varied among cell groups - ranging from indistinct nuclear regions in stromal tumor cells to partially torn nuclei in non-cancerous bronchial epithelial cells. This observation may indicate differences in nuclear structure characteristics. Compared to control samples, stromal regions of both cancer types exhibited denser coverage of striated fibrils with a 67 nm periodicity characteristic to collagen. Standard surface roughness tests on randomly selected sites within sections (tumor and non-malignant) suggest potential for distinguishing malignant from control histology samples. Combining atomic force microscopy with histopathological analysis may offer additional structural insight into lung tissue alterations associated with malignancy.

In the present work, we performed the comprehensive study of real-time interaction between a hybridised DNA aptamer that consists of three self-assembling oligonucleotides (anti-VEGF aptamer) and its target analyte of vascular endothelial growth factor (VEGF). VEGF is responsible for the growth of new blood vessels and is also abundantly present in tumours, making VEGF a prime biomarker for cancer detection. Time-resolved complex formation kinetics was analysed using a sensitive and non-destructive total internal reflection ellipsometry (TIRE) method. The real-time interaction kinetics of VEGF and the anti-VEGF aptamer were optimised, yielding a KD of 0.1 nM, demonstrating high binding affinity. The hybridized DNA structure contributed to a 5-fold enhanced binding affinity compared to the original SL2B aptamer. A comparison with a nonspecific GCSF-SCF dimer binding to anti-VEGF aptamer showed that the binding of VEGF was highly specific and strong, with a significant change in ellipsometric parameters, whereas the GCSF-SCF interaction resulted in a lower signal change. Thermodynamic analysis revealed a Gibbs free binding energy of -56 +/- 2.8 kJ/mol, indicating a thermodynamically favourable interaction of VEGF and anti-VEGF aptamer. The thickness of the VEGF monolayer was calculated to be 5.75 +/- 0.16 nm, consistent with the physical dimensions of VEGF, and the surface mass density was determined to be 62 +/- 2.5 ng/cm2. The study confirms that the immobilization and orientation of aptamer on the sensing surface play a critical role in enhancing VEGF binding efficiency and stability, making such an analytical system highly suitable for biosensing applications.

Bi2Se3, MXenes, and SWCNTs are promising potential alternatives to replace the conventional graphite in the anodes of lithium-ion batteries (LIBs) and enhance their performance. However, all these materials have drawbacks, such as large volume expansion and Se dissolution (Bi2Se3), large irreversible capacity (SWCNTs), and poor specific capacity (MXenes). In this work, a combination of nanostructured Bi2Se3 and MXenes with SWCNTs in Bi2Se3/MXene/SWCNT heterostructures is used as a novel architecture for binder-free anode material in non-aqueous LIBs. Bi2Se3/MXene/SWCNT heterostructures with different Bi2Se3 : MXene : SWCNT mass ratios were fabricated by direct physical vapour deposition of Bi2Se3 nanostructures onto MXene/SWCNT networks. Bi2Se3/MXene/SWCNT heterostructures showed improved electrochemical performance in comparison with the individual components of the heterostructures. This enhancement can be attributed to the high electrode/electrolyte contact area provided by the nanostructured materials, leading to a substantial capacitive contribution to charge storage. In addition, the formation of Se-C bonds on SWCNT surfaces prevented the dissolution of Se. The best performance was shown by Bi2Se3/MXene/SWCNT heterostructures with the mass ratio of 1 : 1 : 2, which reached capacity of 738 mA h g(-1) at 0.1 A g(-1) after 100 cycles. Moreover, after 900 cycles at 10.0 A g(-1) current density, these heterostructures retained an excellent capacity of 320 mA h g(-1). This performance indicates significant potential for Bi2Se3/MXenes/SWCNTs heterostructures as binder-free anodes for high-rate-performance lithium-ion batteries.

The dynamics of coherent acoustic phonons in the Bi2Se3 layered crystal system are investigated. The findings reveal that the frequency evolution of breathing modes with the number of the material quintuple layers and the dispersion relation both can be explained by a modified chain model with a nonuniform coupling force.

Porous anodic aluminum oxide (PAAO), sometimes referred to as nanoporous anodic alumina, serves as a cost-effective template for nanofabrication in many fields of science and engineering. However, production of ultrathin PAAO membranes with precise thickness in the optical sub-wavelength range remains challenging because of difficulties regarding process control at the initial stage of anodic oxidation. In this study, we demonstrate a technique for consistently manufacturing PAAO with the targeted thickness. An electrochemical cell with an optical window was designed for reflectance spectroscopy of PAAO during anodization. Real-time fitting of spectra to a transfer-matrix model enabled continuous monitoring of the thickness growth of the PAAO layer. Automation software was designed to terminate the anodization process at preset PAAO thickness values. While the concept was illustrated using the widely used method of anodization in a 0.3 M oxalic acid electrolyte with a 40 V potential, it can be readily customized for other protocols. PAAO layers with effective thickness below 300 nm could be produced with a few nanometers accuracy using single-crystal aluminum substrates. The results were confirmed using spectroscopic ellipsometry. The method for controlling the thickness during anodization eliminates the necessity of sample sectioning for electron microscopy and is particularly valuable for the small-scale production of PAAO-based functional optical coatings.

This study focuses on the surface engineering of binder-free anodes composed of Bi, Se, Cu, and carbon nanotubes to enhance lithium-ion batteries. The anodes synthesized in this study showed promising electrochemical properties. However, issues with cycle stability, operational speed, and solid electrolyte interface (SEI) formation affected their overall performance. To address these challenges, the study applied different conductive polymers, namely PEO, CMC, and PEGDA-co-VC, to form artificial SEI layers. The application of these polymers altered the stability and efficiency of the electrodes, with the PEGDA-co-VC-coated electrodes demonstrating significant stability and consistent capacity over numerous cycles. The best way to improve the efficiency of lithium-ion batteries without using binders is by creating hybrid anodes. To enhance the stability and performance of these new hybrid anodes, it can be achieved through the development of artificial solid electrolyte interface layers based on conductive polymerimage

Developing vascular endothelial growth factor (VEGF) protein is essential for early cancer diagnosis and cancer treatment monitoring. This study presents the design and characterisation of an electrochemical sensor utilising a self-assembling DNA aptamer structure for the sensitive and selective detection of VEGF. The aptamer structure comprises three different parts of single-stranded DNA that are assembled prior to integration into the sensor. Polypyrrole (Ppy)-based layers were deposited onto screen-printed carbon electrodes (SPCEs) using an electrochemical deposition technique, followed by the entrapment of a self-assembled DNA aptamer structure within electrochemically formed Ppy matrix ((DNA aptamer)/Ppy). The response to the sensor toward VEGF was measured by the pulsed amperometric detection (PAD), highlighting the enhanced performance of DNA aptamer/Ppy configuration compared to bare Ppy. The sensor exhibited high sensitivity, achieving a limit of detection (LOD) of 0.21 nM for VEGF. The interaction behaviour between VEGF in the solution and the immobilise DNA aptamer/Ppy-based structure was analysed using Langmuir isotherm model. The developed electrochemical biosensor is promising for in vitro applications in early cancer diagnostics and treatment monitoring, enabling rapid screening of patient samples.

Bi2Se3 has shown potential for implementation as an anode material for lithium-ion batteries (LIBs), however, the significant volume expansion and dissolution of selenium pose major challenges. In this work, Bi2Se3 nanostructures are synthesized by physical vapor deposition directly on top of a single-wall carbon nanotube (SWCNT) network to fabricate a binder-free Bi2Se3@SWCNT anode materials with different Bi2Se3/SWCNT ratios. Nanostructuring the Bi2Se3 directly on the top of the SWCNT network provides a large accessible contact area and improves mechanical and electrical contact. The heterostructures exhibit capacity, that is beyond the theoretical of pristine Bi2Se3, which can be attributed to the binding of the Se to C, resulting in the resilience against the dissolution of Se, while providing additional electron transport pathways and increased capacitive contribution. A Bi2Se3@SWCNT anode with a mass ratio of (1:1) has the highest capacity in a half-cell after 100 cycles (523 mAh g-1 at 0.1 A g-1) and shows excellent capacity retention after 500 cycles at large current densities (2 A g-1 and 5 A g-1): 1080 mAh g-1 and 809 mAh g-1 respectively. In addition, in a full-cell system Bi2Se3@SWCNT (1:1) delivers high reversible capacity after 150 cycles (484 mAh g-1) at 0.4 A g- 1.

The rapid growth of portable electronic devices, electric vehicles, and grid-scale energy storage systems has accelerated the demand for enhancing existing materials and innovating new materials in rechargeable battery technologies. Li -ion batteries have dominated the energy storage field among the various battery systems. Na -ion batteries have emerged as promising candidates due to their similarities to Li -ion battery chemistry, low cost, and environmental sustainability. This study explores the potential advantages of synthesizing the binder -free Cu 1.9 Bi 0.1 Se@SWCNT heterostructure directly on the copper collector surface. A crucial aspect of this research is the intentional use of nanostructuring during synthesis. This technique capitalizes on the benefits of greater surface area, enhanced electron transport, and superior ionic conductivity. The synthesis method not only ensures excellent electrical and mechanical contact with the collector but also omits the need for a binder, offering a potential for improved overall performance in Li -ion and Na -ion batteries. The electrodes were synthesized using a simple and cost-effective physical vapor deposition method. The structural, morphological, and electrochemical properties of the electrodes were characterized. The binder -free Cu 1.9 Bi 0.1 Se@SWCNT electrode with 25 % SWCNT content exhibits excellent performance in Li -ion half cells, maintaining a high energy capacity of 556 mAh g -1 at 0.1 A g -1 over 100 cycles and 244 mAh g -1 at 0.5 A g -1 over 750 cycles. However, in the Naion battery system, the performance is notably poorer, revealing challenges and limitations. Most likely, the larger size of sodium ions posed difficulties in intercalation within the anode material structure.

Nanodevices consisting of the suspended and supported parts of topological insulator Bi2Se3 nanowires were fabricated and measured at low and room temperatures. Probing of topological surface states, accompanied by the electrostatic field effect used to dynamically manipulate bending deformation, was carried out to monitor the external strain introduced into the suspended and supported parts within the same Bi2Se3 nanowire. Depending on the device geometry, pure elastic and elastoplastic types of concave deformation, as well as convex buckling deformation, were realized in the suspended parts of the nanowires. For various types of observed deformations, different magnitudes of increase in the Source-Drain resistance of the deformed part compared to the relaxed part of the same devices were determined. All suspended devices exhibit external strain-sensitive Shubnikov-de Haas oscillation frequencies representing the carriers of top and bottom surface states and bulk, whereas, in the case of supported devices, the bottom surface states are masked by a trivial 2DEG. The obtained results may be useful for strain engineering of TI materials, as well as for applications in NEMS and other areas related to suspended nanostructures.