Non-destructive low-temperature contacts to MoS2\textrm{MoS}_2 nanoribbon and nanotube quantum dots

Molybdenum disulfide nanoribbons and nanotubes are near-one dimensional semiconductors with strong spin-orbit interaction, a nanomaterial highly promising for quantum electronic applications. Here, we demonstrate that a bismuth semimetal layer between the contact metal and this nanomaterial strongly improves the properties of the contacts. Two-point resistances on the order of $100\textrm{k}\Omega$ are observed at room temperature. At cryogenic temperature, Coulomb blockade is visible. The resulting stability diagrams indicate a marked absence of trap states at the contacts and the corresponding disorder, compared to previous devices using low-work function metals as contacts. Single level quantum transport is observed at temperatures below 100mK.Comment: 7 pages, 5 figure

Coulomb Blockade Spectroscopy of a MoS2 Nanotube

Low-temperature transport spectroscopy measurements on a quantum dot lithographically defined in a multiwall MoS2 nanotube are demonstrated. At T = 300 mK, clear Coulomb blockade is observed, with charging energies in the range of 1 meV. In single-electron tunneling, discrete conductance resonances are visible at finite bias. Additionally, a magnetic field perpendicular to the nanotube axis reveals clear indications of quantum state transitions, with effective g factors consistent with published theoretical predictions

Comparative analysis of prognostic histopathologic parameters in subtypes of epithelioid pleural mesothelioma

Aims: Malignant pleural mesothelioma (MPM) is a rare malignancy with a dismal prognosis. While the epithelioid type is associated with a more favourable outcome, additional factors are needed to further stratify prognosis and to identify patients who can benefit from multimodal treatment. As epithelioid MPM shows remarkable morphological variability, the prognostic role of the five defined morphologies, the impact of the nuclear grading system and the mitosis-necrosis score were investigated in this study. Methods and results: Tumour specimens of 192 patients with epithelioid MPM from five European centres were histologically subtyped. Nuclear grading and mitosis-necrosis score were determined and correlated with clinicopathological parameters and overall survival (OS). Digital slides of 55 independent cases from The Cancer Genome Atlas (TCGA) database were evaluated for external validation. Histological subtypes were collapsed into three groups based on their overlapping survival curves. The tubulopapillary/microcystic group had a significantly longer OS than the solid/trabecular group (732 days versus 397 days, P = 0.0013). Pleomorphic tumours had the shortest OS (173 days). The solid/trabecular variants showed a significant association with high nuclear grade and mitosis-necrosis score. The mitosis-necrosis score was a robust and independent prognostic factor in our patient cohort. The prognostic significance of all three parameters was externally validated in the TCGA cohort. Patients with tubulopapillary or microcystic tumours showed a greater improvement in OS after receiving multimodal therapy than those with solid or trabecular tumours. Conclusions: Histological subtypes of epithelioid MPM have a prognostic impact, and might help to select patients for intensive multimodal treatment approaches

Električne, optične in strukturne lastnosti nizko-dimenzionalnih materialov na osnovi volframa

Substoichiometric tungsten oxides are an interesting class of materials, where defects form periodic structures. These defects are called crystallographic shear (CS) planes and depending on the type of the CS plane and the distance between them, they can form tungsten suboxides with different stoichiometries. In this Thesis quasi-two-dimensional substoichiometric tungsten oxide structures, which nucleate by epitaxial growth on the W$_{19}$O$_{55}$ nanowires and grow as thin platelets, were identified. Both the nanowires and the platelets accommodate oxygen deficiency by formation of crystallographic shear planes. High resolution electron microscopy, x-ray photoelectron spectroscopy and x-ray diffraction were used for structural determination, Raman spectroscopy for vibrational analysis, and optical absorption, Kelvin microscopy and scanning tunnelling spectroscopy for elucidation of electric properties. The used experimental techniques are discussed in the Methods chapter, in the Publication overview chapter an overview of the literature is presented and in the Results and discussion chapter the results are presented and discussed. Stoichiometric phases, W$_{18}$O$_{53}$ (WO$_{2.944}$), W$_{17}$O$_{50}$ (WO$_{2.941}$), W$_{16}$O$_{47}$ (WO$_{2.938}$), W$_{15}$O$_{44}$ (WO$_{2.933}$), W$_{14}$O$_{41}$ (WO$_{2.929}$), W$_{9}$O$_{26}$ (WO$_{2.889}$), and W$_{10}$O$_{29}$ (WO$_{2.9}$), syntactically grow inside a single platelet. Six of the seven identified phases were observed for the first time which were predicted more than 70 years ago. These platelet-like crystals represent a new kind of polycrystallinity, where crystallographic shear planes accommodate oxygen deficiency and at the same time stabilize this multi-stoichiometric structure.Podstehiometrični volframovi oksidi predstavljajo zanimivo vrsto materialov, kjer se defekti uredijo v periodične strukture. Omenjenim periodičnim strukturam pravimo kristalografske strižne ravnine. Glede na tip kristalografske strižne ravnine in razdalje med njimi, te lahko tvorijo volframove okside z različnimi stehiometrijami. V sklopu disertacije so bili identificirani kvazi dvodimenzionalni podstehiometrični volframovi oksidi, ki epitaksialno rastejo na nanožicah W$_{19}$O$_{55}$ kot tanke ploščice. Tako nanožice kot ploščice odpravljajo pomanjkanje kisika s tvorbo kristalografskih strižnih ravnin. Transmisijska elektronska mikroskopija, rentgenska fotoelektronska spektroskopija in rentgenska praškovna difrakcija so bile uporabljene za določitev strukture, Ramanska spektroskopija za analizo nihajnih načinov snovi, UV-Vis spektroskopija, Kelvinova tipalna mikroskopija in vrstična tunelska mikroskopija za določitev električnih lastnosti. Uporabljene metode so predstavljene v poglavju Metode. V poglavju Publikacije so predstavljena zadnja dognanja v literaturi glede omenjenih materialov, v poglavju Rezultati in diskusija pa so predstavljeni rezultati skupaj z diskusijo. Stehiometrične faze, W$_{18}$O$_{53}$ (WO$_{2.944}$), W$_{17}$O$_{50}$ (WO$_{2.941}$), W$_{16}$O$_{47}$ (WO$_{2.938}$), W$_{15}$O$_{44}$ (WO$_{2.933}$), W$_{14}$O$_{41}$ (WO$_{2.929}$), W$_{9}$O$_{26}$ (WO$_{2.889}$) in W$_{10}$O$_{29}$ (WO$_{2.9}$) sintaktično rastejo znotraj ene same ploščice. Šest od sedmih stehiometrij je bilo prvič eksperimentalno opaženih, čeprav so bile predvidene že pred skoraj 70 leti. Ploščicam podobni kristali predstavljajo novo vrsto polikristaliničnosti, kjer kristalografske strižne ravnine odpravljajo pomanjkanje kisika in hkrati stabilizirajo to več stehiometrično strukturo

SEM-EDS datasets of titanium alloy wear debris in periprosthetic tissue

SEM-EDS images and datasets of titanium alloy wear debris found in periprosthetic tissue obtained at revision surgery of a fractured titanium-alloy modular neck of a patient with hip osteoarthritis

The potential of macroporous silica—nanocrystalline cellulose combination for formulating dry emulsion systems with improved flow properties

The objective of this study was to explore the possible use of a new combination of two excipients, i.e., nanocrystalline cellulose (NCC) and macroporous silica (MS), as matrix materials for the compounding of dry emulsion systems and the effects these two excipients have on the characteristics of dry emulsion powders produced by the spray drying process. A previously developed liquid O/W nanoemulsion, comprised of simvastatin, 1-oleoyl-rac-glycerol, Miglyol 812 and Tween 20, was employed. In order to comprehend the effects that these two matrix formers have on the spray drying process and on dry emulsion powder characteristics, alone and in combination, a DoE (Design of Experiment) approach was used. The physicochemical properties of dry emulsion samples were characterised by atomic force microscopy, scanning electron microscopy, mercury intrusion porosimetry, energy-dispersive X-ray spectroscopy and laser diffraction analysis. Additionally, total release and dissolution experiments were performed to assess drug release from multiple formulations. It was found that the macroporous silica matrix drastically improved flow properties of dry emulsion powdershowever, it partially trapped the oil—drug mixture inside the pores and hindered complete release. NCC showed its potential to reduce oil entrapment in MS, but because of its rod-shaped particles deposited on the MS surface, powder flowability was deteriorated

Silicon crystallinity control during laser direct microstructuring with bursts of picosecond pulses

Laser ablation and modification using bursts of picosecond pulses and a tightly focused laser beam are used to manufacture structures in the bulk silicon. We demonstrate precise control of the surface crystallinity as well as the structure depth and topography of the processed areas, achieving homogeneous surface properties. The control is achieved with a combination of a well -defined pulse energy, systematic pulse positioning on the material, and the number of pulses in a burst. A custom designed fiber laser source is used to generate bursts of 1, 5, 10, and 20 pulses at a pulse repetition rate of 40 MHz and burst repetition rate of 83.3 kHz allowing for a fast and stable processing of silicon. We show a controlled transition through different laser -matter interaction regimes, from no observable changes of the silicon at low pulse energies, through amorphization below the ablation threshold energy, to the ablation with either complete, partial or nonexistent amorphization. Single micrometer - sized areas of desired shape and crystallinity were defin ed on the silicon surface with submicron precision, offering a promising tool for applications in thAbstract: Laser ablation and modification using bursts of picosecond pulses and a tightly focused laser beam are used to manufacture structures in the bulk silicon. We demonstrate precise control of the surface crystallinity as well as the structure depth and topography of the processed areas, achieving homogeneous surface properties. The control is achieved with a combination of a well -defined pulse energy, systematic pulse positioning on the material, and the number of pulses in a burst. A custom designed fiber laser source is used to generate bursts of 1, 5, 10, and 20 pulses at a pulse repetition rate of 40 MHz and burst repetition rate of 83.3 kHz allowing for a fast and stable processing of silicon. We show a controlled transition through different laser -matter interaction regimes, from no observable changes of the silicon at low pulse energies, through amorphization below the ablation threshold energy, to the ablation with either complete, partial or nonexistent amorphization. Single micrometer - sized areas of desired shape and crystallinity were defin ed on the silicon surface with submicron precision, offering a promising tool for applications in the field of optics

Size- and time-dependent aerosol removal from a protective box during simulated intubation and extubation procedures

Because the SARS-CoV-2 virus primarily spreads through droplets and aerosols, a protective box could provide adequate protection by shielding medical professionals during the intubation and extubation procedures from generated droplets and aerosols. In this study, size- and timedependent aerosol concentrations were measured inside and outside the protective box in the particle size ranging from 14 nm to 20 µm during simulated intubation and extubation procedures. An improved protective box with active ventilation was designed based on a plastic bag with armholes covered with latex sheets that utilizes a supportive frame. Coughing during the intubation and extubation procedure was simulated using an aerosol generator which dispersed the aerosol powder into the protective box. During the intubation and extubation procedure, the concentration of particles increased inside the protective box but, due to the high negative airflow, quickly dropped to background levels. The particle concentration of all measured particle sizes decreased within the same time frame. No leakage of particles was observed through the armhole openings. The presented protective box design provides excellent protection against generated droplets and aerosols. The decrease in concentration does not depend on the particle size. Outside the box, particle concentration did not change with time

Single-layer and double-layer filtration materials based on polyvinylidene fluoride-co-hexafluoropropylene nanofibers coated on melamine microfibers

In this work, we demonstrate selected optimization changes in the simple design of filtration masks to increase particle removal efficiency (PRE) and filter quality factor by combining experiments and numerical modeling. In particular, we focus on single-layer filters fabricated from uniform thickness fibers and double-layer filters consisting of a layer of highly permeable thick fibers as a support and a thin layer of filtering electrospun nanofibers. For single-layer filters, we demonstrate performance improvement in terms of the quality factor by optimizing the geometry of the composition. We show significantly better PRE performance for filters composed of micrometer-sized fibers covered by a thin layer of electrospun nanofibers. This work is motivated and carried out in collaboration with a targeted industrial development of selected melamine-based filter nano- and micromaterials