Benedykt R. Jany

Synthesis of new metastable nanoalloys of immiscible metals with a pulse laser technique

The generation of nanoalloys of immiscible metals is still a challenge using conventional methods. However, because these materials are currently attracting much attention, alternative methods are needed. In this article, we demonstrate a simple but powerful strategy for the generation of a new metastable alloy of immiscible metals. Au1−xNix 3D structures with 56 at% of nickel in gold were successfully manufactured by the pulsed laser irradiation of colloidal nanoparticles. This technology can be used for preparing different metastable alloys of immiscible metals. We hypothesise that this technique leads to the formation of alloy particles through the agglomerations of nanoparticles, very fast heating, and fast cooling/solidification. Thus, we expect that our approach will be applicable to a wide range of inorganic solids, yielding even new metastable solids that fail to be stable in the bulk systems, and therefore do not exist in Nature.

Preformulation Studies on Solid Self-Emulsifying Systems in Powder Form Containing Magnesium Aluminometasilicate as Porous Carrier

The influence of alkaline and the neutral grade of magnesium aluminometasilicate as a porous solid carrier for the liquid self-emulsifying formulation with ibuprofen is investigated. Ibuprofen is dissolved in Labrasol, then this solution is adsorbed on the silicates. The drug to the silicate ratio is 1:2, 1:4, and 1:6, respectively. The properties of formulations obtained are analyzed, using morphological, porosity, crystallinity, and dissolution studies. Three solid self-emulsifying (S-SE) formulations containing Neusilin SG2 and six consisting of Neusilin US2 are in the form of powder without agglomerates. The nitrogen adsorption method shows that the solid carriers are mesoporous but they differ in a specific surface area, pore area, and the volume of pores. The adsorption of liquid SE formulation on solid silicate particles results in a decrease in their porosity. If the neutral grade of magnesium aluminometasilicate is used, the smallest pores, below 10 nm, are completely filled with liquid formulation, but there is still a certain number of pores of 40–100 nm. Dissolution studies of liquid SEDDS carried out in pHu2009=u20091.2 show that Labrasol improves the dissolution of ibuprofen as compared to the pure drug. Ibuprofen dissolution from liquid SE formulations examined in pH of 7.2 is immediate. The adsorption of the liquid onto the particles of the silicate causes a decrease in the amount of the drug released. Finally, more ibuprofen is dissolved from S-SE that consist of the neutral grade of magnesium aluminometasilicate than from the formulations containing the alkaline silicate.

Protocol of single cells preparation for time of flight secondary ion mass spectrometry.

There are several techniques like time of flight secondary ion mass spectrometry (ToF SIMS) that require a special protocol for preparation of biological samples, in particular, those containing single cells due to high vacuum conditions that must be kept during the experiment. Frequently, preparation methodology involves liquid nitrogen freezing what is not always convenient. In our studies, we propose and validate a protocol for preparation of single cells. It consists of four steps: (i) paraformaldehyde fixation, (ii) salt removal, (iii) dehydrating, and (iv) sample drying under ambient conditions. The protocol was applied to samples with single melanoma cells i.e. WM115 and WM266-4 characterized by similar morphology. The surface and internal structures of cells were monitored using atomic force, scanning electron and fluorescent microscopes, used to follow any potential protocol-induced alterations. To validate the proposed methodology for sample preparation, ToF SIMS experiments were carried out using C60(+) cluster ion beam. The applied principal component analysis (PCA) revealed that chemical changes on cell surface of melanoma cells were large enough to differentiate between primary and secondary tumor sites. Subject category: Mass spectrometry.

Probing the electronic transport on the reconstructed Au/Ge(001) surface

Summary By using scanning tunnelling potentiometry we characterized the lateral variation of the electrochemical potential µec on the gold-induced Ge(001)-c(8 × 2)-Au surface reconstruction while a lateral current flows through the sample. On the reconstruction and across domain boundaries we find that µec shows a constant gradient as a function of the position between the contacts. In addition, nanoscale Au clusters on the surface do not show an electronic coupling to the gold-induced surface reconstruction. In combination with high resolution scanning electron microscopy and transmission electron microscopy, we conclude that an additional transport channel buried about 2 nm underneath the surface represents a major transport channel for electrons.

Controlled growth of hexagonal gold nanostructures during thermally induced self-assembling on Ge(001) surface

Nano-sized gold has become an important material in various fields of science and technology, where control over the size and crystallography is desired to tailor the functionality. Gold crystallizes in the face-centered cubic (fcc) phase, and its hexagonal closed packed (hcp) structure is a very unusual and rare phase. Stable Au hcp phase has been reported to form in nanoparticles at the tips of some Ge nanowires. It has also recently been synthesized in the form of thin graphene-supported sheets which are unstable under electron beam irradiation. Here, we show that stable hcp Au 3D nanostructures with well-defined crystallographic orientation and size can be systematically created in a process of thermally induced self-assembly of thin Au layer on Ge(001) monocrystal. The Au hcp crystallite is present in each Au nanostructure and has been characterized by different electron microscopy techniques. We report that a careful heat treatment above the eutectic melting temperature and a controlled cooling is required to form the hcp phase of Au on a Ge single crystal. This new method gives scientific prospects to obtain stable Au hcp phase for future applications in a rather simple manner as well as redefine the phase diagram of Gold with Germanium.

Defect-Assisted Hard-X-Ray Microscopy with Capillary Optics.

Polycapillary x-ray focusing devices are built from hundreds of thousands of bent microcapillaries that are stacked into hexagonal arrays. We show that intrinsic point defects of the optics (e.g., missing or larger capillaries) lead to the formation of multiple x-ray images of an object positioned in the focal plane. These images can be recorded in parallel, and can provide spatial resolution that is limited by the defect size and not by the focal spot size. In a proof-of-principle experiment, we demonstrate submicron resolution, which has not yet been achieved with polycapillary focusing optics. Tailored optics with a controlled distribution of defects could be used for multimodal nanoscale x-ray imaging with laboratory setups.

Urinary Extracellular Vesicles: Potential Biomarkers of Renal Function in Diabetic Patients

The aim of this study was to check the relationship between the density of urinary EVs, their size distribution, and the progress of early renal damage in type 2 diabetic patients (DMt2). Patients were enrolled to this study, and glycated hemoglobin (HbA1c) below 7% was a threshold for properly controlled diabetic patients (CD) and poorly controlled diabetic patients (UD). Patients were further divided into two groups: diabetic patients without renal failure (NRF) and with renal failure (RF) according to the Glomerular Filtration Rate. Density and diameter of EVs were determined by Tunable Resistive Pulse Sensing. Additionally, EVs were visualized by means of Transmission and Environmental Scanning Electron Microscopy. Nano-liquid chromatography coupled offline with mass spectrometry (MALDI-TOF-MS/MS) was applied for proteomic analysis. RF had reduced density of EVs compared to NRF. The size distribution study showed that CD had larger EVs (mode) than UD (115 versus 109u2009nm; p < 0.05); nevertheless the mean EVs diameter was smaller in controls than in the CD group (123 versus 134u2009nm; p < 0.05). It was demonstrated that EVs are abundant in urine. Albumin, uromodulin, and number of unique proteins related to cell stress and secretion were detected in the EVs fraction. Density and size of urinary EVs reflect deteriorated renal function and can be considered as potential renal damage biomarkers.

Dynamics of thermally induced assembly of Au nanoislands from a thin Au layer on Ge(001)

The dynamics of morphology changes upon post-deposition annealing of a thin film of 6 ML Au deposited on a (2 × 1) reconstructed Ge(001) surface was studied in a systematic way by scanning electron and atomic force microscopy. It has been found that annealing of the initial, continuous Au layer leads to the development of nanoislands which are crystalline and epitaxial to the Ge(001) substrate surface. The nanoislands formed at annealing temperatures lower than the bulk eutectic temperature for the Au–Ge system (634 K) are rectangular, with a flat top, while the nanoislands developed by annealing at temperatures higher than the bulk eutectic temperature have more complex, octagonal shapes. Moreover, the octagonal Au nanoislands are nearly half-buried in the Ge substrate and surrounded by a crystalline Ge rim.

Multipoint-projection x-ray microscopy

Point projection is a mature geometry of x-ray imaging that is implemented in scientific and industrial applications. Objects to be imaged are placed near a microscopic x-ray source, and the magnification is accomplished by x-ray propagation towards a distant detector. The source size is a trade-off between the signal level and the spatial resolution. In this work, we demonstrate multipoint-projection x-ray imaging realized with an x-ray tube and compound structured microcapillary optics that generates nearly one thousand submicrometer secondary x-ray sources. The generated microbeams are multiplexed at the object. Demultiplexing of the transmitted beams, magnification, and phase contrast are achieved by the free-space propagation. A massive improvement in the signal-to-noise ratio, relative to a single secondary source, was achieved without a loss in spatial resolution. Hence, x-ray projections of highly absorbing samples at submicrometer spatial resolution could be recorded with only a few photons per detector pixel. For weakly absorbing samples, the multipoint-projection method enabled us to record, in a parallel way, replicated in-line x-ray holograms with incoherent radiation from an x-ray tube. Our method may enrich the panel of x-ray nanoscale imaging techniques and may be adopted for on-chip x-ray photonic devices.

Tailoring of Magnetic Properties of NiO/Ni Composite Particles Fabricated by Pulsed Laser Irradiation

We present NiO/Ni composite particles with face-centered cubic (fcc) structure prepared by a pulsed laser irradiation of NiO nanoparticles dispersed in liquid. The sizes of particles and the Ni content in NiO/Ni composites were controlled by tuning the laser parameters, such as laser fluence and irradiation time. We found that the weight fraction of Ni has a significant impact on magnetic properties of composite particles. Large exchange bias (HEB) and coercivity field (HC) were observed at 5 K due to the creation of heterojunctions at interfaces of ferromagnetic Ni and antiferromagnetic NiO. For the NiO/Ni composites with 80% of NiO we have observed the largest values of exchange bias (175 Oe) and coercive field (950 Oe), but the increase of Ni weight fraction resulted in the decrease of both HC and HEB values.