Investigations of Electron Properties of Carbon Nanotubes Decorated with Platinum Nanoparticles with Their Varying Fraction

The paper presents the outcomes of investigations into electron properties and a qualitative and quantitative analysis of the chemical composition of unmodified carbon nanotubes with comparison to nanotubes decorated with platinum nanoparticles. The fabricated nanocomposite materials of the CNT-Pt type differed in a varying mass concentration of platinum nanoparticles (5, 10, and 20% of Pt). X-ray photoelectron spectroscopy (XPS) was employed to examine the structure and to analyse chemical composition. Survey spectra measurements within a wide range of the binding energy of 0-1400 eV were performed in the first phase of the investigations. The core lines of C1s carbon, Pt4f platinum, and O1s oxygen and a valence band were then measured. The chemical composition of the studied materials was determined based on the measured spectra of the core lines. The purpose of the investigations is to determine the effect of platinum nanoparticles on the structure and electron properties of the fabricated CNT-Pt nanocomposites

Photofunctionalization of titanium: an alternative explanation of its chemical-physical mechanism

Objectives To demonstrate that titanium implant surfaces as little as 4 weeks from production are contaminated by atmospheric hydrocarbons. This phenomenon, also known as biological ageing can be reversed by UVC irradiation technically known as photofunctionalization. To propose a new model from our experimental evidence to explain how the changes in chemical structure of the surface will affect the adsorption of amino acids on the titanium surface enhancing osteointegration. Methods In our study XPS and AES were used to analyze the effects of UVC irradiation (photofunctionalization) in reversing biological ageing of titanium. SEM was used to analyze any possible effects on the topography of the surface. Results UVC irradiation was able to reverse biological ageing of titanium by greatly reducing the amount of carbon contamination present on the implant surface by up to 4 times, while the topography of the surface was not affected. UVC photon energy reduces surface H2 O and increases TiOH with many -OH groups being produced. These groups explain the superhydrophilic effect from photofunctionalization when these groups come into contact with water. Significance Photofunctionalization has proven to be a valid method to reduce the amount of hydrocarbon contamination on titanium dental implants and improve biological results. The chemisorption mechanisms of amino acids, in our study, are dictated by the chemical structure and electric state present on the surface, but only in the presence of an also favourable geometrical composition at the atomical level

Synthesis and characterisation of PEG-peptide surfaces for proteolytic enzyme detection

Peptide surfaces were obtained by the covalent immobilisation of fluorescently labelled pentapeptides carboxyfluorescein–glycine–arginine–methionine–leucine–glycine, either directly or through a poly(ethylene glycol) (PEG) linker on modified silicon wafers. Each step during the preparation of the peptide surfaces was confirmed by several surface characterisation techniques. Time-of-flight secondary ion mass spectrometry (ToF-SIMS) and X-ray photoelectron spectroscopy were used to determine the surface composition, the wafers philicity was measured by contact angle and atomic force microscopy was used to investigate the surface morphology. Exposure of the peptide surfaces to trypsin resulted in the release of a fluorescently labelled peptide product, which allowed the kinetics of the enzymatic reaction to be followed with the aid of fluorescence spectroscopy. The electrospray ionisation mass spectrometry analysis of the post-digestion solution confirmed that the pentapeptides attached to the solid support undergo specific trypsin hydrolysis at the C-terminus of the arginine residues. Detailed surface analyses before and after the enzyme action was performed using ToF-SIMS. Because of the limited accessibility of the short peptide directly attached to the surface, a quantitative yield of enzymatic hydrolysis was observed only in case when the peptide was bound through the PEG linker. The insertion of the PEG linker increased the number of immobilised peptides and the rate of enzymatic digestion which consequently improved the quality of the enzyme assays. The described approach may be used for different peptide sequences designed for other proteases. Figure Monitoring of trypsin hydrolysis on PEG-peptide surfac

Dielectric and electromagnetic interference shielding properties of high entropy (Zn,Fe,Ni,Mg,Cd) Fe2O4 ferrite

The new (Zn,Mg,Ni,Fe,Cd)Fe2O4 high entropy ferrite with average crystallite size 11.8 nm was synthesized in two stages by annealing of co-precipitated amorphous precursor. The dielectric spectroscopy confirms, that the electrical conductivity and polarization processes are associated with the mobility of electrons in the structure of ferrite. It was concluded, that the both, high frequency complex dielectric permittivity as well as complex magnetic permeability are strongly temperature and frequency dependent. The AC electrical conductivity is associated with quantum mechanical tunneling of electrons and related to the transfer of charge carriers between Fe2+ and Fe3+ ions. Moreover, the microwave absorption properties were determined. The best microwave absorption properties have been confirmed in the frequency range 1.9 to 2.1 GHz for a layer which is 0.8–1 cm thick. For this range, reflection loss (RL) is lower than −25 dB and shielding effectiveness (SE) lower than −50 dB

Evaluation of Bacterial Adhesion to the ZrO2 Atomic Layer Deposited on the Surface of Cobalt-Chromium Dental Alloy Produced by DMLS Method

The main purpose of the research was to analyze the influence of surface modification of the cobalt-based alloy used in dental prosthetics by applying zirconium oxide (ZrO2) layers using the ALD (Atomic Layer Deposition) method. The samples were made using the DMLS (Direct Metal Laser Sintering) technique, and their surfaces were prepared in accordance with the principles of removable partial dentures (RPDs). A 50 nm-thick zirconium oxide coating was applied to the prepared substrates. This paper deals with the issues of prosthetic stomatopathy, which is a complex of pathological changes occurring in approx. 40% of the Polish population using removable dentures. Often, these changes, occurring on the mucosa, are related to improper performance, allergic reactions or the multiplication of bacteria on the surface of partial dentures. An innovative method of surface modification was proposed, together with the analysis of its influence on the physicochemical properties of the alloy and the adhesion of bacteria to the surface

Effect of graphene material structure and iron oxides deposition method on morphology and properties of graphene/iron oxide hybrids

In this work, various facile approaches were applied to prepare hybrids of graphene nanoplatelets (GNPs) and graphene oxide (GO) with iron oxides (IO) nanoparticles (NPs). The IO NPs were synthesized and deposited on the graphene surfaces via: (1) co-precipitation using Fe (II) and Fe (III) salts, (2) homogeneous precipitation of Fe2O3 from FeCl3 solution, (3) the attaching of Fe2O3 NPs functionalized with 3-aminopropyltrimethoxysilane to graphene surfaces of GO and GNPs. The effects of the graphene material and preparation procedure on the structural characteristics of the hybrids were studied. Their morphology was studied by scanning electron microscopy and transmission microscopy. Lattice parameters and crystallite sizes of the synthesized hybrid materials were assessed by X-ray diffraction. Raman spectroscopy was used to determine the change of order degree of graphene structures as a results of IO NPs deposition and interactions IO NPs with graphene sheets. Binding energy for IO NPs and graphene structures were determined by photoelectron X-ray spectroscopy. Thermogravimetric analysis was applied to find differences in the thermal stability of hybrids. The hybrids are proposed as nanofillers to polymer composites, however they have large potential applications as supercapacitors, advanced anode materials for lithium-ion batteries, magnetically targeted drug delivery, and magnetic resonance imaging

Pd decorated Co-Ni nanowires as a highly efficient catalyst for direct ethanol fuel cells

The storage and conversion of energy necessitates the use of appropriate electrochemical systems and chemical reaction catalysts. This work presents newly developed catalysts for electrooxidation of ethanol in an alkaline medium. Nanocatalysts composed of Co–Ni nanowires (Co–Ni NWs) decorated with Pd nanoparticles (Pd NPs) were made at varying metal ratios and their chemical composition and structure was investigated in detail. The synthesis involved a wet chemical reduction assisted by a magnetic field, which led to the generation of NWs, followed by the deposition of spherical Pd NPs on their surface. The best catalytic activity was obtained for the catalyst made of Co3–Ni7 decorated with Pd NPs, which exhibited EOR of 8003 mA/mgPd for only 0.86 wt% of Pd loading. The results can be explained by the synergistic effect between the morphology of the bimetallic support and the favorable interaction of oxophilic Co, Ni with catalytic Pd

Nanolayers of Poly(N,N’-Dimethylaminoethyl Methacrylate) with a Star Topology and Their Antibacterial Activity

In this paper, we focus on the synthesis and characterization of novel stable nanolayers made of star methacrylate polymers. The e ect of nanolayer modification on its antibacterial properties was also studied. A covalent immobilization of star poly(N,N0-dimethylaminoethyl methacrylate) (PDMAEMA) to benzophenone functionalized glass or silicon supports was carried out via a “grafting to” approach using UV irradiation. To date, star polymer UV immobilization has never been used for this purpose. The thickness of the resulting nanolayers increased from 30 to 120 nm with the molar mass of the immobilized stars. The successful bonding of star PDMAEMA to the supports was confirmed by surface sensitive quantitative spectroscopic methods. Next, amino groups in the polymer layer were quaternized with bromoethane, and the influence of this modification on the antibacterial properties of the obtained materials was analyzed using a selected reference strain of bacteria. The resulting star nanolayer surfaces exhibited higher antimicrobial activity against Bacillus subtilis ATCC 6633 compared to that of the linear PDMAEMA analogues grafted onto a support. These promising results and the knowledge about the influence of the topology and modification of PDMAEMA layers on their properties may help in searching for new materials for antimicrobial applications in medicine

An innovative method of fibrous flax harvesting and processing the raw material into one-type (homomorphic) fibre

W Instytucie Włókien Naturalnych i Roślin Zielarskich opracowano efektywną technologię zbioru lnu włóknistego z przeznaczeniem na włókno jednopostaciowe z jednoczesnym pozyskaniem nasion. Len włóknisty jest rośliną, która wymaga stosowania drogich, specjalistycznych maszyn do wyrywania, pielęgnacji i zbioru słomy. W miejsce specjalistycznych maszyn, zaproponowano wykorzystanie kombajnów zbożowych. Celem wydobycia włókna, słomę po skoszeniu trzeba wyrosić. Zabieg roszenia polega na wyściełaniu słomy na plantacji. Na wyściełaną słomę działają mikroorganizmy grzybowe, które powodują rozkład pektyn łączących włókno z drewnikiem. Aby proces roszenia przebiegał równomiernie, wyściełaną słomę należy odwracać. Do odwracania słomy wykorzystano dostępne w większości gospodarstw rolnych maszyny, zbiór wyroszonej słomy prowadzony był przy wykorzystaniu pras rolujących. W artykule przedstawiono prace adaptacyjne mające na celu dostosowanie wytypowanych kombajnów zbożowych do koszenia lnu. Przedstawiono również wyniki doświadczenia polowego. Słomę lnianą przerabiano wykorzystując opracowaną linię. Otrzymane włókno jednopostaciowe poddano ocenie metrologicznej a następnie wyprodukowano doświadczalne partie przędzy lnianej, którą także przebadano laboratoryjnie.At the Institute of Natural Fibres and Medicinal Plants in Poznań, an effective technology of fibrous flax harvesting intended for one-type (homomorphic) fibre with simultaneous seed production has been developed. Fibrous flax is a plant that requires the use of expensive, specialized machines for pulling, maintaining and harvesting straw. Instead of specialized machines, it was proposed to use cereal combine harvesters. In order to extract the fiber, the straw must be dew retted after it is mowed. The retting procedure consists in padding the straw in the field in the plantation. The retted straw is affected by fungal microorganisms and in the process of degumming, fibres are separated from adhesive substances like hemicelluloses, pectin, and partially from lignin, waxes and fats. To ensure that the retting process is even, the retted straw should be turned over at least twice. The machines available in most farms were used to turn the straw over, while the harvest of the retted straw was conducted with the use of round balers. The article presents adaptation works aimed at adjustment of selected cereal combine harvesters to flax mowing. The results of the field experiment are also presented. Flax straw was processed using the developed line. The obtained homomorphic fibre was subjected to metrological evaluation, and then experimental batches of linen yarn were produced, which were also tested in the laboratory