Point-contact Andreev reflection spectroscopy at low temperatures and high magnetic fields has been performed on a noncentrosymmetric La3Se4 superconductor with a critical temperature T c = 8 K. Two superconducting energy gaps A 1 and A 2 , with 2A1/kBTc similar to 5.8 and 2A2/kBTc similar to 2.3, are directly observed in some of the spectra. The temperature and magnetic field effects help to resolve a two-gap structure even on the most frequent spectra where at low temperatures only a single gap is apparent, reflected in a pair of maxima around the zero bias. Two-gap superconductivity consistently with the point contact Andreev reflection spectroscopy is also supported by the heat capacity and the Hall probe magnetization measurements.

One of the major functions of the larval salivary glands (SGs) of many Drosophila species is to produce a massive secretion during puparium formation. This so-called proteinaceous glue is exocytosed into the centrally located lumen, and subsequently expectorated, serving as an adhesive to attach the puparial case to a solid substrate during metamorphosis. Although this was first described almost 70 years ago, a detailed description of the morphology and mechanical properties of the glue is largely missing. Its main known physical property is that it is released as a watery liquid that quickly hardens into a solid cement. Here, we provide a detailed morphological and topological analysis of the solidified glue. We demonstrated that it forms a distinctive enamel-like plaque that is composed of a central fingerprint surrounded by a cascade of laterally layered terraces. The solidifying glue rapidly produces crystals of KCl on these alluvial-like terraces. Since the properties of the glue affect the adhesion of the puparium to its substrate, and so can influence the success of metamorphosis, we evaluated over 80 different materials for their ability to adhere to the glue to determine which properties favor strong adhesion. We found that the alkaline Sgs-glue adheres strongly to wettable and positively charged surfaces but not to neutral or negatively charged and hydrophobic surfaces. Puparia formed on unfavored materials can be removed easily without leaving fingerprints or cascading terraces. For successful adhesion of the Sgs-glue, the material surface must display a specific type of triboelectric charge. Interestingly, the expectorated glue can move upwards against gravity on the surface of freshly formed puparia via specific, unique and novel anatomical structures present in the puparial’s lateral abdominal segments that we have named bidentia.

After deposition of gold layers by evaporation, granular droplets ranging in size from one to several tens of nanometers commonly remain on the surface. In such metal nanostructures, localized surface plasmons can be formed upon interaction with light, similar to the case of gold nanoparticle layers. We have proposed a parametric material model that describes the effective refractive index of a 5 nm thick Au layer on Si substrate with roughness of a few nanometers based on the multioscillator Lorentz permittivity model.

In a previous study (2017 Phys. Rev. B 96 144501), a strong variation in the superconducting transition temperature T c of YB 6 differing by a factor of two has been explained by a change in the density of yttrium and boron vacancies tuning the electron–phonon interaction. Here, by using an array of miniature Hall probes, we address the penetration of the magnetic field, pinning, and critical current density on a series of YB 6 single crystals with T c variation between 4.25 and 7.35 K. The analysis of the superconducting and normal-state specific heat characteristics allowed us to determine T c and the stoichiometry of our samples. We observed almost no pinning in the most stoichiometric YB 6 crystal with the lowest T c . Upon increasing the number of vacancies weak pinning appears, and the critical current density is enhanced following the increased transition temperature in a linear variation. We argue that such an increase is, within weak collective pinning theory, consistent with the increasing number of vacancies that serve as pinning centers.

We study magnetic force microscopy tips with a ferromagnetic disk-shaped apex (FMD tip). We find that it behaves as a paramagnetic-like tip when scanning large domains, i.e., it visualizes only the domain boundaries. Moreover, it significantly reduces the perturbation of soft magnetic samples and provides a longer probe lifetime compared to commercial low-moment probes. FMD tip was tested on a Co-based sample with out-of-plane magnetization and on a longitudinal magnetic media with in-plane recording. We prepared two FMD tips with disk diameters of 150 and 325 nm in order to analyze how the disk diameter affects the probe sensitivity and the measured width of the domain wall. Experimental results are supported by analytical calculations and numerical simulations.

We theoretically study the performance and limitations of the magnetic vortex probe for magnetic force microscopy (MFM). In the ideal case, the only magnetically active part of the probe is the magnetic vortex core (VC) existing in the center of a Permalloy (Py) disk located at the apex of a nonmagnetic tip. Such VC can be effectively characterized as a point dipole with the magnetic moment of the order of $10^{-17}\text {Am}^{2}$ embedded about 20 nm inside the disk, which is similar to the commercial text low-momentum MFM probes. In addition to the standard probes, the ideal VC probe offers high durability and a text well-controlled magnetic moment suitable for quantitative MFM. However, since the VC probe is made of magnetically soft material its magnetization profile and the resulting MFM image can be deformed by the stray field of the sample. Therefore, the VC probe is suited for imaging the samples with small domain sizes which generate low stray fields. We numerically examine VC imaging of typical magnetic samples, i.e., domain arranged as a single circular dot, stripe patterns, and the chessboard. We determine the limiting dimensions of the domains that can be correctly imaged by the VC tip of optimal parameters. In general, we can conclude that MFM imaging by VC probes gives reasonable results for the samples with domains with lateral dimensions up to 100 nm.

A deep eutectic solvent Ethaline, composing of choline chloride (vitamin B 4) and ethylene glycol, is pre-sented as electrochemical surface modification agent for Ti6Al4V alloy. The possibility of creation of highly rough topography with cell-sized micropits for successful bioinspiration by electrochemical etch-ing is demonstrated and probed in depth. STEM-EDS investigation is clarifying the dissolution process of a and 0-Ti phases in the alloy and the formation of amorphous nano-sized TiOx tubular units as the dis-solution products. EELS plasmon mapping and MLLS fitting is used to attest the absence of hydrides that could lead to severe material degradation. Outermost layer, which consists mainly of Cl and O with a thickness of ti 50 nm, is detected only after electrochemical etching of Ti6Al4V alloy in Ethaline.(c) 2023 Elsevier B.V. All rights reserved.

This study investigates the impact of a combined approach involving sandblasting and electrochemical surface treatment using a deep eutectic solvent Ethaline, a eutectic mixture of choline chloride and ethylene glycol, on the surface characteristics of Ti–6Al–4V biomedical substrates fabricated through direct selective laser melting (DSLM). Research has focused on surface morphology, topography, chemical composition, and cell adhesion. The novel approach demonstrated the ability to create a hierarchical surface structure with both micro and nanopatterns. The rough edges resulting from the sandblasting process were effectively smoothed through subsequent electrochemical processing. Additionally, the issue of residual sand particles, which commonly arise in sandblasting procedures, was successfully addressed with the new method. The results indicated that Ti alloy samples subjected to sandblasting and electrochemical treatment in Ethaline exhibited improved surface hydrophilicity. In-vitro cell adhesion tests confirmed the potential for bio-inspired properties of DSLM-printed Ti–6Al–4V biomedical substrates achieved through the combination of sandblasting and electrochemical processing in Ethaline.

Mordellistena A. Costa, 1854, the most species-rich genus of tumbling flower beetles comprises more than 800 species worldwide and more than 150 reported from Europe. Here, a new species Mordellistena (s. str.) platypoda is described from the island of Ischia in Italy. The species hypothesis is based primarily on morphological characters which are visualised using scanning electron microscopy images, high-resolution photographs, and drawings. The species hypothesis is supported by analysis of a 658 bp fragment of cytochrome c oxidase subunit I (COI). Divergences in the COI gene are evaluated using maximum likelihood and Bayesian inference analyses. The species delimitation is assessed using Assemble Species by Automatic Partitioning (ASAP) and Poisson Tree Processes (PTP) methods. Genetic distances are visualised using multidimensional scaling. Mordellistena platypoda Selnekovič, Goffová & Kodada, sp. nov. is recovered as a well-separated species by both molecular and morphological analyses. Our results show that M. platypoda Selnekovič, Goffová & Kodada, sp. nov. is most closely related to M. tarsata Mulsant, 1856, although the two species differ significantly in vestiture colouration, presence of lateral ctenidia on the third metatarsomere, and presence of sexual dimorphism on the protibia. The results indicate that such morphological differences, which were traditionally used to distinguish between species groups, may in fact be present between closely related species. Interestingly, examination of the numerous museum material did not reveal additional specimens of the new species, and therefore M. platypoda Selnekovič, Goffová & Kodada, sp. nov. is currently known only from the Italian island of Ischia.

This study demonstrates the possibility of the design of Ti-6Al-4V alloy surface properties by galvanostatic electrochemical treatment in a deep eutectic solvent Ethaline (a eutectic mixture of choline chloride and ethylene glycol in molar ratio 1:2, respectively) at the temperature of 25 degrees C. A short-time anodic treatment in Ethaline in a wide range of current densities (2-50 mA cm(-2)) provides formation of surface oxide films with controllable chemical composition, roughness and wettability, improved corrosion resistance and with biologically-inspired topography. It was found that a unique feature of this electrolyte in comparison with traditional acidic ones is that oxidation is not observed during electrochemical processing of titanium alloy. It was shown that formation of microrough structure on Ti-6Al-4V alloy surfaces is observed at relatively low current densities (2-15 mA cm(-2)) of the electrochemical treatment; formation of nanorough structure occurs at higher current densities (20-50 mA cm(-2)). It was found that all treated samples did not demonstrate any cytotoxic effect and have good cells adhesion and cells viabilities. Bacterial resistance of Ti-6Al-4V alloy samples can be controllably adjusted and increased by the surface leveling in Ethaline at high current densities.

Vortex-Core magnetic force microscopy (VC MFM) promises magnetic tip durability and long-term calibration of its magnetic moment that is crucial for quantitative scanning. It uses the vortex core of a ferromagnetic disk located at the tip apex as a magnetic probe. However, our experience showed that MFM images might be distorted when scanning magnetic objects larger than 100 nm due to a VC shift generated by the stray field of the scanned sample. We addressed the problem by changing the tip geometry and introducing artificial VC pinning at the disk center. These steps are essential for improving the VC tip for quantitative scanning. The scanning experiments with the optimized VC tip showed improved characteristics of the magnetic images - spatial resolution of the tip was on the level of commercial MFM tip with certain details depicted even better.

This paper reports the results of the study on electrochemical polishing of Ti-based alloy using an ecologically friendly deep eutectic solvent, Ethaline. The electropolishing treatment was performed in a potentiostatic mode (E=+3.0 V and E=+4.0 V) at the temperature of 25 °C for 30–40 min. It was shown that the electropolishing in Ethaline ensured the removal of surface defects, thereby providing surface smoothing and decreasing surface roughness. The atomic-force microscopy revealed that the electrochemical polishing of titanium alloy in Ethaline yielded formation of specific surface patterns with nanoscale irregularities in the form of prolonged hemispheres. The correlations between surface roughness coefficients and wettability parameters were established and discussed. The electrochemical processes occurring during electrochemical polishing of Ti-based alloy in Ethaline were examined. The adjustment of processing time and electrode potential of electropolishing allows controllably and flexibly tuning the surface roughness and wettability of titanium-containing alloy. It issuggested that the electropolishing of the surfaces of Ti-based alloys in deep eutectic solvent can be successfully used for the processing of different biomedical products.

The magnetization properties of the endohedral cluster superconductor Mo 8 Ga 41 are studied by sensitive Hall-probe magnetometry. The temperature dependence of the lower critical magnetic field H c 1 is obtained and compared to theoretical models accounting for single-gap and two-gap superconductivity. Data can be described by both models with minor differences. These results are confronted with our previous measurements which evidence that the system is inherently single-gap s -wave superconductor but minor additional phases are present also in seemingly perfect samples. We discuss how presence of such additional phases with varying size of the penetration depth and H c 1 field is reflected in magnetization measurements which could lead to misinterpretation of the multigap superconductivity in Mo 8 Ga 41 .

Understanding the stability of magnetic textures in multilayer patterned dots would constitute a significant step toward skyrmion-based applications. Here, we report the observation of skyrmions in patterned nanodots composed of multilayers. We examine the stabilization of various magnetic states such as single-domain states, skyrmion states, horseshoe-like domain structures, and worm-like domain structures in submicrometer dots (diameters 150–525 nm). Dots are fabricated from Pt/Co/Au multilayer structures that exhibit the interfacial Dzyaloshinskii–Moriya interaction and perpendicular magnetic anisotropy. In particular, we show that a stack of six repetitions of Pt/Co/Au layers suffices to stabilize the skyrmion state inside a dot at room temperature. A micromagnetic simulation determines the regime of skyrmion stability. The results reveal a correlation between the magnetic-force microscopy measurements and the micromagnetic simulation. Furthermore, we explain the development of the magnetic state with increasing dot diameter. We envision that nanopatterning of multilayer magnetic films could serve as a versatile way of creating magnetic skyrmion states.

Transparent conducting Al-doped ZnO films were grown by atomic layer deposition (ALD). Al-doping was introduced by inserting 1 Al2O3 cycle per 28 ZnO cycles. The x-ray photoelectron spectroscopy showed that the density of the Al donors is 2×1021–3×1021 cm−3, while the Hall-effect measurements showed a ten times lower electron density. This low doping efficiency is a well-known inherent problem of the ALD method, and we wanted to explain its origin. We have found that the electron density is reduced by electron traps at the grain surface; however, the effect was too weak to explain the low doping efficiency. Therefore, the mechanism of the Al2O3 doping was analyzed. We have proposed that each Al2O3 molecule ideally provides two single-electron Al donors accompanied by one Zn vacancy, which acts as a two-electron acceptor. This would cause a perfect compensation; however, the compensation is in reality not perfect, which results in weakly efficient doping. Calculations also showed that each Zn vacancy creates a bound pair with an Al donor. To verify our doping model experimentally, it was inserted into the metallic transport theory and compared with the electron transport measurements. A good agreement was found for a broad range of experimental conditions. In the regime of weak localization, the conductivity showed the temperature dependence σ(T)=a+bT3/4, which is a signature of weak localization and electron–electron scattering in a 3D dirty metal.

We report on the properties of metal-insulator-semiconductor (MIS) photoanodes for water oxidation employing a thin RuO2-(IrO2) film as a top catalytic layer. In this study, MIS photoanodes with the configurations RuO2/SiO2/n-Si and IrO2-RuO2/SiO2/n-Si were prepared and their photoelectrochemical (PEC) oxygen evolution under solar irradiation has been discussed. The thin SiO2 layers were prepared by the atomic layer deposition method and the RuO2-(IrO2) thin layers were deposited by the metal-organic chemical vapor deposition method. The photocurrent and photovoltage of these MIS photoanodes were studied in 1 M aq. H2SO4 (pH = 0), 0.5 M aq. Na2SO4 (pH = 6), and 1 M aq. KOH (pH = 14) electrolytes showing the trend acidic > alkaline > near-neutral pH conditions for both RuO2- and IrO2-RuO2-based structures. The RuO2/SiO2/n-Si photoanode exhibited a photovoltage of 0.49 V and was able to generate a photocurrent of similar to 10 mA/cm(2) at a thermodynamic water oxidation potential (1.23 V vs the normal hydrogen electrode, NHE) in 1 M aq. H2SO4 solution under 1 Sun intensity with AM 1.5 spectrum. A photovoltage of 0.42 V and a photocurrent of similar to 4 mA/cm(2) were achieved for the IrO2-RuO2/SiO2/n-Si photoanode under acidic conditions. The stability of the photoanodes was examined in 1 M aq. H2SO4 and 1 M aq. KOH solutions. Chronoamperometry measurements on the RuO2/SiO2/n-Si photoanode in acidic solution under an applied voltage of 1.23 V versus NHE showed the deterioration of the photoanode after 2 h of operation. Similarly, stability measurements were performed on IrO2-RuO2/SiO2/n-Si photoanodes in 1 M aq. H2SO4 solution. Under acidic conditions, at an applied bias of 1.23 V versus NHE, a photocurrent of similar to 2 mA/cm(2) was observed, which was stable for 24 h for the IrO2-RuO2-based photoanodes. The preparation, PEC activity, stability, and characterization of the RuO2/SiO2/n-Si and IrO2-RuO2/SiO2/n-Si have been discussed in our study.

We demonstrated numerically the skyrmion formation in ultrathin nanodisks using a magnetic force microscopy tip. We found that the local magnetic field generated by the magnetic tip significantly affects the magnetization state of the nanodisks and leads to the formation of skyrmions. Experimentally, we confirmed the influence of the local field on the magnetization states of the disks. Micromagnetic simulations explain the evolution of the magnetic state during magnetic force microscopy scanning and confirm the possibility of skyrmion formation. The formation of the horseshoe magnetic domain is a key transition from random labyrinth domain states into the skyrmion state. We showed that the formation of skyrmions by the magnetic probe is a reliable and repetitive procedure. Our findings provide a simple solution for skyrmion formation in nanodisks.

We have developed a vortex-core magnetic force microscope (VC MFM) for magnetic field imaging at the nanoscale for many research fields-physics, biology, materials science, and metrology. The method solves principally quantitative scanning by increasing magnetic tip durability and introducing its calibration. We show that nature itself gives us a sharp, durable, and calibrated magnetic probe. It is represented by a narrow magnetic vortex core located in the center of a ferromagnetic disk placed at the apex of a scanning tip. Such a tip offers potentially high spatial resolution-the vortex core is magnetically sharp (the vortex diameter is<20nm for Permalloy), but at the same time, the disk is geometrically blunt and therefore durable. The magnetic moment of the vortex core is independent of the disk diameter and can be tuned smoothly by the disk thickness. We describe here the basic properties of the VC tip, its technology, and sensitivity to the magnetic field and show its durability. The first results obtained on hard disk drive are promising-from the analysis of data tracks, the spatial resolution of the VC tip is only a bit worse than the one of the standard MFM tips. We believe that the VC tip could be a sensor of choice for magnetic field imaging for scientific areas mentioned above.