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Mateusz Wierzbicki,1 Katarzyna Zawadzka,1 Barbara Wójcik,1 Sławomir Jaworski,1 Barbara Strojny,1 Agnieszka Ostrowska,1 Artur Małolepszy,2 Marta Mazurkiewicz-Pawlicka,2 Ewa Sawosz1 1Department of Nanobiotechnology, Institute of Biology, Warsaw University of Life Sciences, Warsaw, 02-786, Poland; 2Faculty of Chemical and Process Engineering, Warsaw University of Technology, Warsaw, 00-654, PolandCorrespondence: Mateusz Wierzbicki, Department of Nanobiotechnology, Institute of Biology, Warsaw University of Life Sciences, Ciszewskiego 8, Warsaw, 02-786, Poland, Tel +48 22 5936676, Email mateusz_wierzbicki@sggw.edu.plIntroduction: Diamond nanoparticles are considered to be one of the most cytocompatible carbon nanomaterials; however, their toxicity varies significantly depending on the analysed cell types. The aim was to investigate the specific sensitivity of endothelial cells to diamond nanoparticles dependent on exposure to nanoparticles.Methods: Diamond nanoparticles were characterized with Raman spectroscopy, Fourier-transform infrared spectroscopy (FTIR) and dynamic light scattering (DLS). Toxicity of diamond nanoparticles was assessed for endothelial cells (HUVEC), human mammary epithelial cells (HMEC) and HS-5 cell line. The effect of diamond nanoparticles on the level of ROS, NO, NADPH and protein synthesis of angiogenesis-related proteins of endothelial cells was evaluated.Results and Discussion: Our studies demonstrated severe cell type-specific toxicity of diamond nanoparticles to endothelial cells (HUVEC) depending on nanoparticle surface interaction with cells. Furthermore, we have assessed the effect on cytotoxicity of the bioconjugation of nanoparticles with a peptide containing the RGD motive and a serum protein corona. Our study suggests that the mechanical interaction of diamond nanoparticles with the endothelial cell membranes and the endocytosis of nanoparticles lead to the depletion of NADPH, resulting in an intensive synthesis of ROS and a decrease in the availability of NO. This leads to severe endothelial toxicity and a change in the protein profile, with changes in major angiogenesis-related proteins, including VEGF, bFGF, ANPT2/TIE-2, and MMP, and the production of stress-related proteins, such as IL-6 and IL-8.Conclusion: We confirmed the presence of a relationship between the toxicity of diamond nanoparticles and the level of cell exposure to nanoparticles and the nanoparticle surface. The results of the study give new insights into the conditioned toxicity of nanomaterials and their use in biomedical applications.Keywords: diamond nanoparticles, endothelial cells, nanotoxicity, oxidative toxicity

In order to ensure the highest level of maritime travel safety, standards and rules are applied aimed at eliminating potential risks. In view of changes in the environment – as a result of, among others, the Covid-19 pandemic and Russia’s aggression against Ukraine – it has become necessary to verify expec-tations and preferences towards the provision of maritime transport services from the perspective of its users, representing generation Y. A key factor for evaluating cruise maritime service in the situation of current threats was identi-fied to achieve the objective of this study. At the same time, groups of factors responsible for the emergence of threats to travelers were identified, and pro-posals for measures to increase confidence in maritime transportation were evaluated from the perspective of the surveyed participants.

Reprezentanci pokolenia Y podejmują decyzje konsumenckie w rzeczywistości VUCA. Wykazują silne preferencje w zakresie przygotowania i organizacji podróży, dla których wzory realizacji oparte zostały o własne poczucie bezpieczeństwa. Skutki trwającej pandemii Covid-19 oraz wojny w Ukrainie stały się impulsem dla weryfikacji oczekiwań i preferencji osób urodzonych w latach 1982-2002 w zakresie świadczenia handlowej usługi lotniczej. Na podstawie opinii respondentów przynależących do pokolenia Y, potwierdzono redefinicję bezpieczeństwa wybranych środków transportu wobec otaczającej rzeczywistości i zidentyfikowano zależność pomiędzy oceną jakości pasażerskiego transportu lotniczego a poczuciem bezpieczeństwa.

To reduce emissions of exhaust particles, using oils with improved properties has been proposed. Nanoadditives can be used to enhance lubricating properties of engine oils. Although many additives have been developed, molybdenum disulfide and carbon nanotubes have attracted significant attention. In this study, we demonstrate that hybrid nanostructures based on these unique materials (MoS2/CNTs) positively affect lubricating properties of the engine oil. Hybrid nanostructures were produced via wet chemical synthesis in impinging jet reactor. This method is characterized by easy scalability and possible continuous operation, which are crucial in material commercialization. Various concentrations of the oil nanoadditives were tested. The application of 0.5 wt% suspension produced the best results, reducing the friction factor at the engine operating temperature by up to 26%. Nanoadditives protected the lubricated parts, causing their wear to be considerably lower than the base oil. The effect of nanoadditives on the quality of exhaust gases was also investigated. The application of the oil with MoS2/CNT reduced the emissions of solid particles in the exhaust gas of a gasoline engine. This research showed that MoS2/CNTs can be successfully used as nanoadditives in engine oils for improving tribological properties, enhancing anti-wear performance, and reducing particle emissions in exhaust gas.

Nucleic acid extraction and purification are crucial steps in sample preparation for multiple diagnostic procedures. Routine methodologies of DNA isolation require benchtop equipment (e.g., centrifuges) and labor-intensive steps. Magnetic nanoparticles (MNPs) as solid-phase sorbents could simplify this procedure. A wide range of surface coatings employs various molecular interactions between dsDNA and magnetic nano-sorbents. However, a reliable, comparative evaluation of their performance is complex. In this work, selected Fe3O4 modifications, i.e., polyethyleneimine, gold, silica, and graphene derivatives, were comprehensively evaluated for applications in dsDNA extraction. A family of single batch nanoparticles was compared in terms of morphology (STEM), composition (ICP-MS/MS and elemental analysis), surface coating (UV-Vis, TGA, FTIR), and MNP charge (ζ-potential). ICP-MS/MS was also used to unify MNPs concentration allowing a reliable assessment of individual coatings on DNA extraction. Moreover, studies on adsorption medium (monovalent vs. divalent ions) and extraction buffer composition were carried out. As a result, essential relationships between nanoparticle coatings and DNA adsorption efficiencies have been noticed. Fe3O4@PEI MNPs turned out to be the most efficient nano sorbents. The optimized composition of the extraction buffer (medium containing 0.1 mM EDTA) helped avoid problems with Fe3+ stripping, which improved the validity of the spectroscopic determination of DNA recovery.

The influence of preparation conditions of the graphene foams on their physicochemical properties is shown. Different graphene aerogels were obtained from various graphene oxide water suspensions using the hydrothermal method (with or without the addition of acrylic microemulsion and varying in drying time—24 and 48 h). Prolonged drying of the hydrogels resulted in smaller pores in the foams. The composition of graphene oxide (GO) and acrylic polymer water suspensions leads to the smallest surface area which is due to the closing of the pores of the composite structure. Thermal treatment of samples at 950 °C removed the polymer residues. The heating process increased the surface area and the total pore volume of all samples, which were used to test the graphene foams (GFs) for adsorption of n-hexane. These tests have shown that the most effective samples for n-hexane adsorption were the samples where for the preparation of the composite GO and acrylic resin were used. The best of obtained samples adsorbed 415 mg g−1 of n-hexane which is a better result than for activated carbon manufactured from natural cork. Further preparation and modification of graphene foams could result in a significant increase in their sorption properties and could be used for contaminated air purification in the nearest future.

Developing functional materials from biomass is a significant research subject due to its unique structure, abundant availability, biodegradability and low cost. A series of chitosan–lignin (CL) composites were prepared through a hydrothermal method by varying the weight ratio of chitosan and lignin. Subsequently, these CL composites were combined with titania (T) to form a nanocomposite (T/CL) using sol–gel and hydrothermal based methods. T/CL nanocomposites exhibited improved photocatalytic performance in comparison with sol–gel and hydrothermally prepared pristine titania (SGH-TiO2), towards the selective oxidation of benzyl alcohol (BnOH) to benzaldehyde (Bnald) under UV (375 nm) and visible light (515 nm). More specifically, the 75T/CL(25 : 75) nanocomposite (a representative photocatalyst from the 75T/CL nanocomposite series) showed very high selectivity (94%) towards Bnald at 55% BnOH conversion under UV light. Whereas, SGH-TiO2 titania exhibited much lower (68%) selectivity for Bnald at similar BnOH conversion. Moreover, the 75T/CL(25 : 75) nanocomposite also showed excellent Bnald selectivity (100%) at moderate BnOH conversion (19%) under visible light. Whereas, SGH-TiO2 did not show any activity for BnOH oxidation under visible light. XPS studies suggest that the visible light activity of the 75T/CL(25 : 75) nanocomposite is possibly related to the doping of nitrogen into titania from chitosan. However, according to UV-visible-DRS results, no direct evidence pertaining to the decrease in band-gap energy of titania was found upon coupling with the CL composite and the visible light activity was attributed to N-doping of titania. Overall, it was found that T/CL nanocomposites enhanced the photocatalytic performance of titania via improved light harvesting and higher selectivity through mediation of active radical species.

This work is focused on determining whether two graphene derivatives: graphene oxide (GO) and reduced graphene oxide (RGO) can be used alone as a component of anticancer therapy. In this paper, we present the synthesis GO and RGO, their physicochemical characterization as well as an evaluation of their cytotoxic properties on cancer (HepG2 and MCF-7) and non-malignant (clone-9 and HMF) cells. We demonstrated that both tested graphene derivatives have a high affinity to cancer cells. We showed that cytotoxic properties of GO and RGO were different depending on the type of solvent in which they were prepared. Additionally, we observed that cytotoxic properties of GO and RGO were different depending on the origin of the cells (liver and breast) and the form of graphene material (GO and RGO). We showed that GO and RGO can be potential, selectively materials which in future can found application in anticancer therapy.

Anodes consisting of Pd and bimetallic PdCu catalysts deposited directly on a carbon cloth by magnetron sputtering have been tested in a direct formic acid fuel cell. Current-voltage measurements showed that a bimetallic Pd-based catalyst temperature-treated to 300 °C exhibits the highest catalytic activity. Chemical and structural information from the surface of the catalysts was revealed by X-ray photoelectron spectroscopy (XPS) and by scanning electron microscopy (SEM). Increasing the temperature of the anode together with hydrogen peroxide (H2O2) treatment of the catalyst surface was proposed as an additional treatment method. In this method, the highest catalytic activity was achieved (P = 56 mW mg−1) for a monometallic Pd catalyst. The enhanced catalytic efficiency after these methods had been applied was attributed to the decrease in the content of metal oxide forms, carbon-oxygen groups, and PdCx surface contamination, where the PdCx surface content played a major role.

Background: Graphene oxide (GO) has unique physical and chemical properties that can be used in anticancer therapy - especially as a drug carrier. Graphene oxide, due to the presence of several hybrid layers of carbon atoms (sp2), has a large surface for highly efficient drug loading. In addition, GO with a large number of carboxyl, hydroxyl and epoxy groups on its surface, can charge various drug molecules through covalent bonds, hydrophobic interactions, hydrogen bonds and electrostatic interactions. Objective: The aim of our work was to evaluate the possibility of future use of graphene oxide as an anticancer drug carrier. Method: In this paper, we present GO synthesis and characterization, as well as a study of its biological properties. The cytotoxic effect of well-defined graphene oxide was tested on both carcinoma and non-malignant cells isolated from the same organ, which is not often presented in the literature. Results: The performed research confirmed that GO in high concentrations (> 300 µgmL-1) selectively decreased the viability of cancer cell line. Additionally, we showed that the GO flakes have a high affinity to cancer cell nucleus which influences their metabolism (inhibition of cancer cell proliferation). Moreover, we have proved that GO in high concentrations can cause cell membrane damage and generate reactive oxygen species on a low level mainly in cancer cells. Conclusion: The proposed GO could be useful in anticancer therapy. A high concentration of GO selectively causes the death of tumor cells, whereas GO with low concentration could be a potential material for anticancer drug loading.

In this study, an electrochemical sensor toward mercury ion was developed. As the sensing material directly-thiolated graphene (G-SH) was used. After the graphene synthesis and its characterization (elemental analysis, FT-IR and Raman spectroscopy, scanning electron microscopy), the best measurement conditions were chosen and working parameters of the sensor were evaluated. The G-SH thin film was formed on the glassy carbon electrode surface by drop-casting. Mercury ion concentration was determined with the use of voltammetric techniques by comparison of current change of redox indicator hexaammineruthenium(III) chloride. As was found, the sensor response is strictly dependent on the G-SH amount deposited at the electrode surface and the pH of the sample. The prepared sensor demonstrated linear response within the range of 5 × 10−9 to 5 × 10−7 mol L−1 and high selectivity towards Hg(II) ion over other examined cations (e.g. Sr2+, Fe3+, Co2+, Pb2+, Mg2+ and for Ca2+).

Lepidoptera together with its sister group Trichoptera belongs to the superorder Amphiesmenoptera, which is closely related to the Antliophora, comprising Diptera, Siphonaptera, and Mecoptera. In the lepidopteran Pieris napi, a representative of the family Pieridae, the ovaries typical of butterflies are polytrophic and consist of structural ovarian units termed ovarioles. Each ovariole is composed of a terminal filament, germarium, vitellarium, and ovariole stalk. The germarium houses developing germ cell clusters and somatic prefollicular and follicular cells. The significantly elongated vitellarium contains linearly arranged ovarian follicles in successive stages of oogenesis (previtellogenesis, vitellogenesis, and choriogenesis). Each follicle consists of an oocyte and seven nurse cells surrounded by follicular epithelium. During oogenesis, follicular cells diversify into five morphologically and functionally distinct subpopulations: (1) main body follicular cells (mbFC), (2) stretched cells (stFC), (3) posterior terminal cells (pFC), (4) centripetal cells (cpFC), and (5) interfollicular stalk cells (IFS). Centripetal cells are migratorily active and finally form the micropyle. Interfollicular stalk cells derive from mbFC as a result of mbFC intercalation. Differentiation and diversification of follicular cells in Pieris significantly differ from those described in Drosophila in the number of subpopulations and their origin and function during oogenesis.

Palladium catalysts deposited on carbon nanotubes are used as the anode material in a direct formic acid fuel cell (DFAFC). In this paper we propose a simple method for enhancing the catalytic activity of Pd deposited on carbon nanotubes for formic acid electrooxidation by using ammonia solution. Multiwall carbon nanotubes (MWCNTs) used as the catalyst support are oxidized with concentrated nitric acid for 6 and 50 h. During the oxidation polynuclear aromatic compounds (PACs) are formed. We propose the use of ammonia solution after the oxidation process to remove the PACs from the carbon nanotubes surface. The properties of differently functionalized MWCNTs are studied and the results show that the use of ammonia solution removes the PACs formed during the oxidation process. The oxidation time of the carbon nanotubes has also a significant effect on the properties of the obtained catalysts. The palladium catalysts deposited on MWCNTs oxidized for a shorter time and rinsed with ammonia solution exhibit the highest initial activity in electrooxidation of formic acid in DFAFC (P = 216 mW mgPd−1).

Municipal waste management is one of the most serious challenges that the municipality must face. The article presents the most important rules as well as legal regulations regarding municipal waste management. An assessment of the present state of municipal waste management was undertaken based on the example of the municipality of Żagań. Conclusions were drawn on the basis of decision-making, retrospective and estimated analyzes. They include the answer to the question: “Is it possible to optimize the costs of municipal waste management keeping good waste management results?” Waste prevention methods have been proposed. The need to implement recycling of biodegradable waste was considered. The author of the article focuses his attention on the economic aspect of waste management, shows possible solutions in the field of waste management, and also underlines the signifiant role of public education in this respect. Gospodarka odpadami komunalnymi należy do poważniejszych wyzwań, którym stara się sprostać gmina. W artykule przedstawiono najważniejsze podstawy i uregulowania prawne dotyczące gospodarki odpadami komunalnymi. Na przykładzie gminy Żagań podjęto próbę oceny stanu gospodarki odpadami komunalnymi. W tym celu poddano analizie trzy inne gminy. Na podstawie przeprowadzonych analiz: decyzyjnej, retrospektywnej, zgromadzonych dokumentów sformułowano wnioski i odpowiedź na pytanie: „Czy jest możliwe optymalizowanie kosztów gospodarki odpadami komunalnymi przy dobrych wynikach zagospodarowania odpadów?”. Zaproponowano sposoby zapobiegania powstawaniu odpadów. Rozważono potrzebę wdrożenia recyklingu odpadów biodegradowalnych. Autorka artykułu koncentruje się na aspekcie ekonomicznym zagospodarowania odpadów, przytacza możliwe rozwiązania w sferze gospodarki odpadami, a także podkreśla znaczącą rolę edukacji społeczeństwa w tej kwestii.

On the ventral tube of males of Onychiuroides granulosus (Stach, 1934) there is a male ventral organ, which consists of two groups of four setae that are thickened, slightly flattened and bent. All setae of the male ventral organ are inserted in a richly sculptured cuticle. At the base of each seta there are a few large cells (basal cells) that have large irregular nuclei that contain a large amount of heterochromatin. In the cytoplasm of the basal cells there are numerous mitochondria, ribosomes and a rich system of endoplasmic reticulum. The plasma membrane of the basal cells forms richly folded, deep invaginations, filled with a dense material, which also occurs in particular setae and on their surface. The present study indicates that the male ventral organ is secretory and does not confirm its previously suggested sensory function.

Owing to its low friction coefficient, nanosized MoS2 is as an excellent lubricant additive that can enhance the durability and efficiency of internal combustion engines. Herein, we investigate the application of MoS2-based materials as additives for a 10W-40 engine under different working conditions. To improve rheological and tribological properties, the heterogeneous nucleation was used to deposit MoS2 nanoparticles on surface of different carbon nanomaterials, such as graphene oxide, reduced graphene oxide, and carbon nanotubes, using an impinging jet reactor. Adding MoS2-based nanomaterials enhanced the rheological and tribological properties of the engine oil. At temperatures above 0 °C, adding hybrid materials decreased the friction factor between the engine oil and nanosuspension by up to 55%.

This paper describes the relationship between the arrangement of dermal chromatophores in tokay gecko (Gekko gecko) skin and the formation of wild-type colouration, with emphasis on the ultrastructure of chromatophores. The samples of the tokay gecko skin were collected from wild-type colouration adult specimens. Morphology and distribution of chromatophores was determined by using light microscopy and transmission electron microscopy. The present study revealed that orange/red coloured skin of G. gecko contained erythrophores, which were located under basement membrane, and usually comprised deeper situated iridophores and melanophores which were form single layer with iridophores or were occupying the deepest region of dermis. In orange/red coloured skin, erythrophores were the predominant chromatophores. However in blue areas these cells occurred in small numbers or were not noticed at all. In blue pigmented areas predominated iridophores and melanophores. Iridophores were found just under basement membrane, but this superficial location of iridophores occured only in areas without erythrophores. Distribution of erythrophores, melanophores, and iridophores determines the characteristic blue colour of the tokay gecko skin with orange/red dots on the whole body.

Infrared (IR) shielding materials are commonly used for different applications, such as smart windows or optical filters. Infrared radiation is responsible for about 50% of the energy coming from the sun. During a hot summer or cold winter a lot of energy is needed to keep the optimal temperature inside buildings and means of transport. To reduce the heat transmission and save energy IR shielding materials can be used as coatings made of polymer composites. Graphene oxide (GO) and its reduced forms have interesting IR absorption properties and might be used as a filler in a polymer matrix for IR shielding applications. Graphene oxide can be reduced by different methods. Depending on the reduction method reduced graphene oxide (rGO) with a different content of oxygen can be obtained exhibiting different properties. In this work we propose new polymer nanocomposites with poly(vinyl alcohol) as the matrix and 0.1 wt.% addition of graphene materials with different oxygen content to be used for IR shielding applications. The results show that the properties of the graphene filler strongly influence the infrared shielding properties of the obtained nanocomposites. The best IR shielding properties were obtained for the composites where rGO with the lowest oxygen content was used.

Non-covalent nanohybrids composed of cationic 5,10,15,20-tetra(4-trimethylammoniophenyl)porphyrin tetra(p-toluenesulfonate) (TMAP) and the graphene oxide sheets were prepared under two pH values (6.2 vs. 1.8). The TMAP molecule was positively charged, regardless of the pH value during preparation. However, protonation of the imino nitrogens increased the overall charge of the porphyrin molecule from +4 to +6 (TMAP4+ and TMAP6+ ). It was found that at acidic pH, interaction of TMAP6+ with GO was largely suppressed. On the other hand, results of FTIR, Raman spectroscopy, thermogravimetric analysis, atomic force microscopy (AFM) and elemental analysis confirmed effective non-covalent functionalization of graphene oxide with cationic porphyrin at pH 6.2. The TMAP4+ -GO hybrids exhibited well defined structure with a monolayer of TMAP4+ on the GO sheets as confirmed by AFM. Formation of the ground-state TMAP4+ -GO complex in solution was monitored by the red-shift of the porphyrin Soret absorption band. This ground-state interaction between TMAP4+ and GO is responsible for the static quenching of the porphyrin emission. Fluorescence was not detected for the nanohybrid which indicated that a very fast deactivation process had to take place. Ultrafast time-resolved transient absorption spectroscopy clearly demonstrated the occurrence of electron transfer from the photoexcited TMAP4+ singlet state to GO sheets, as proven by the formation of a porphyrin radical cation.

Noncovalent nanohybrids between meso-(p-hydroxyphenyl)porphyrin (TPPH) and graphene oxide (GO)sheets were studied as a function of pH. The overall charge of theTPPH molecule changes between negative (−4), neutral, and positive (+2) depending on the pH of the solution. Results of Fourier transform infrared spectroscopy, thermogravimetricanalysis, and elemental analysis confirm successful noncovalent functionalization of GO sheets with TPPH. We applied a numberof methods to probe the ground-state as well as the excited-state interaction between the components of the new material. The experimental results were additionally supported by theoretical calculations that included optimizations of the ground-state structures of TPPH and TPPH2+and their complexes with amolecular model of GO. It was demonstrated that both TPPHand TPPH2+molecules can be assembled onto the surface of GO, but it was clearly shown that the stronger interaction with GO occurs for TPPH2+. The stronger interaction in the acidic environment can be rationalized by the electrostatic attraction between positively charged TPPH2+ and negatively charged GO, whereas the interaction between TPPH4−and GO at basic pH was largely suppressed. Our comprehensive analysis of the emission quenching led to the conclusion that it was solely attributed to static quenching of the porphyrin by GO. Surprisingly,fluorescence was not detected for the nanohybrid, which indicates thata very fast deactivation process must take place. Ultrafast time-resolved transient absorption spectroscopy demonstrated that although the singlet excited-state lifetime of TPPH2+adsorbed on the GO sheets was decreased in the presence of GO from 1.4ns to 12 ps, no electron-transfer products were detected. It is highly plausible that electron transfer takes place and is followed by fast back electron transfer.

One of the drawbacks of low-temperature fuel cells is high price of platinum-based catalysts used for the electroreduction of oxygen at the cathode of the fuel cell. The aim of this work is to develop the palladium catalyst that will replace commonly used platinum cathode catalysts. A series of palladium catalysts for oxygen reduction reaction (ORR) were prepared and tested on the cathode of Direct Formic Acid Fuel Cell (DFAFC). Palladium nanoparticles were deposited on the carbon black (Vulcan) and on multiwall carbon nanotubes (MWCNTs) surface by reduction of palladium(II) acetate dissolved in ethanol. Hydrazine was used as a reducing agent. The effect of functionalization of the carbon supports on the catalysts physicochemical properties and the ORR catalytic activity on the cathode of DFAFC was studied. The supports were functionalized by treatment in nitric acid for 4 h at 80 °C. The structure of the prepared catalysts has been characterized by thermogravimetric analysis (TGA), X-ray diffraction (XRD), transmission electron microscope (TEM) and cyclic voltammetry (CV). Hydrophilicity of the catalytic layers was determined by measuring contact angles of water droplets. The performance of the prepared catalysts has been compared with that of the commercial 20 wt.% Pt/C (Premetek) catalyst. The maximum power density obtained for the best palladium catalyst, deposited on the surface of functionalized carbon black, is the same as that for the commercial Pt/C (Premetek). Palladium is cheaper than platinum, therefore the developed cathode catalyst is promising for future applications.

Impact of Pd/MWCNTs catalysts preparation method on the catalysts morphology and activity in a formic acid electrooxidation reaction was investigated. Three reduction methods of Pd precursor involving reduction in a high pressure microwave reactor (Pd1), reduction with NaBH4 (Pd2) and microwave-assisted polyol method (Pd3) were used in this paper. Crystallites size and morphology were studied using the scanning transmission electron microscopy (STEM), X-ray diffraction (XRD), whereas elemental composition, Pd chemical state and functional groups content by the X-ray photoelectron spectroscopy (XPS). The prepared catalysts were tested in a direct formic acid fuel cell (DFAFC) as an anode material. The catalytic activity was correlated with a mean fraction of the total Pd atoms exposed at the surface (FE). The value of FE was calculated from the crystallites size distribution determined by the STEM measurements. Non-linear dependence of a current density versus FE, approaching the maximum at FE≈0.25 suggests that the catalytic process proceeded at Pd nanocrystallites faces, with inactive edges and corners. Pd2 catalyst exhibited highest activity due to its smallest Pd crystallites (3.2 nm), however the absence of Pd crystallites aggregation and low content of carbon in PdCx phase, i.e. x = 4 at.% may also affect the observed.

The presented studies aimed at investigation of the effect of CdSeS/ZnS quantum dots (QDs) stabilized with hyperbranched polyglycidol and its carboxylated derivative on adenocarcinomic human alveolar basal epithelial cells (A549). The first stage of studies concerned the modification of quantum dots with both types of the tested polymers with the use of pyridine as an intermediate agent. Subsequently, cytotoxic effect of the prepared nanoparticles was examined after various incubation time using MTT test (cell metabolic activity assay). Our studies revealed that CdSeS/ZnS with a diameter of 6nm, which were stabilized with hyperbranched polymers do not penetrate into cells, even after prolonged incubation time. Moreover, the cytotoxic effect of the tested QDs was observed over a range of tested concentrations (5-90μM of Cd(2+)). It was confirmed that tested nanoparticles had significant influence on cell culture viability. The examined cytotoxic effect of the tested quantum dots was dependent on the type of polymer applied and the experiments indicated, that the one bearing carboxylic moieties is more toxic to A549 cells.

In a psychodid, Tinearia alternata, the initial differentiation of the polytrophic ovary occurs during the early larval stages. Early in development, each ovary anlage is a solid organ subdivided into three distinct zones: the cortex houses germ cells and somatic interstitial tissue, while two other somatic regions will give rise to the oviduct calyx and anterior part of the lateral oviduct. Germ cell cluster formation precedes the development of ovarioles. Each ovariole houses only one functional egg chamber. All ovarioles within paired ovaries are developmentally synchronized. In the larval ovaries, the newly formed egg chambers and then the ovarioles are intermingeled with and surrounded by the somatic interstitial tissue of the ovary cortex. The interstitial cells give rise to all the somatic elements of the ovarioles. In the pupal ovaries, the remaining interstitial tissue degenerates; thus, the ovarioles protrude into the body cavity. The ovaries in psychodids develop relatively large and swollen oviduct calyxes that are equivalent to receptaculum seminis (spermatheca). The morphological differentiation of germ cells within the egg chambers starts during late larval/early pupal stages. Nurse cell nuclei contain prominent nucleoli and polytene chromosomes. Oocyte growth results from accumulation of yolk and then, in the final stages of oogenesis, from an inflow of cytoplasm from the nurse cells. J. Morphol. 236:167-177, 1998. © 1998 Wiley-Liss, Inc.

One of the main problems of palladium based catalysts for a direct formic acid fuel cell (DFAFC) is their low stability during a long-term operation. In these studies, the Pd-ZrO2 catalyst supported on the multiwall carbon nanotubes (MWCNTs) was prepared and thermo-chemically treated. These catalysts were tested in a fuel cell for formic acid electrooxidation, and their chemical composition and structure were characterised by the XPS, STEM, HR-TEM and XRD techniques. It was found that the Pd-ZrO2/MWCNTs catalyst after synthesis causes oscillations of the cell voltage during operation resulting in significantly higher deactivation resistance than that of Pd/MWCNTs. This may be attributed to the "self-cleaning" mechanism of poisoned Pd catalyst by carbon monoxide through the electrochemical oxidation of COads (adsorbed) to CO2 (gas).

The aim of this study was to describe the ultrastructure and arrangement of pigment cells in the leopard gecko (Eublepharis macularius) skin to explain how wild-type coloration is formed. The study also attempted to explain, on a morphological level, how skin colour changes occur. Samples of leopard gecko skin were collected from wild-type coloration adult specimens. The morphology of pigmented cells was determined using light microscopy on haematoxylin and eosin (H&E) stained sections and in transmission electron microscopy. These studies indicate that skin of E. macularis contains xanthophores and melanophores but lacks iridophores and that this is probably related to nocturnal activity. The number and distribution of xanthophores and melanophores determines the skin colour and pigmentation pattern. The colour changes depend on the arrangement of characteristic protrusions of melanophores and the degree of filling them with melanosomes.

Diamond powder with an average particle size of 200 μm was coated with tungsten and tungsten carbide coatings of thickness 260 nm. Pulse Plasma Sintering (PPS) was then used to fabricate copper/diamond composites with a 1:1 volume ratio. The composition and structure of the composites, their components and interfacial phases were studied by XRD, SEM, X-ray, FTIR and Raman spectroscopy. The methods to assess the thermal conductivity of diamond based on nitrogen impurity content determined from FTIR spectrum were examined. The ITC was calculated from the measured composite conductivity using comparatively the Differential Effective Medium (DEM) model and the Hasselman–Johnson (H–J) equation. The composite with W coated diamond particles had the thermal conductivity of 690 W/(m K) and the ITC of 45 MW/(m2 K). The PPS process induced chemical reactions – carbidization of the coatings on diamond W → W2C → WC – when forming the filler/matrix interface within the composite. Raman spectroscopy was able to detect the formation of a thin (∼10–100 nm) restructured sublayer of carbon which is transitional from diamond to graphite in result of the deposition of the tungsten coating on the facets of the diamond particles, a sublayer of turbostratic carbon being formed in result of subsequent sintering.

The aim of the present work is to study the magnetic properties of ZrO2(Fe) nanocrystals prepared by the wet chemistry method. The microwave assisted hydrothermal synthesis was used. The detailed structural characterization was performed by means of X-ray diffraction and TEM studies. 57 Fe Mossbauer spectra were recorded at room temperature for all samples. The isomer shift and quadrupole splitting indicate the presence of Fe 3+ ions. The systematic measurements of AC magnetic susceptibility up to 350 K and magnetization as a function of magnetic field (up to 9 T) and temperature were performed. Depending on the nominal concentration of magnetic dopant different types of magnetic behavior, were observed. 2015 Elsevier B.V. All rights reserved.

The effect of laser wavelength on single-wall carbon nanotubes synthesis yield and their properties was studied. A double-pulse Nd:YAG laser, working at a wavelength of 355 or 1064 nm, was used for carbon nanotubes production. The synthesized carbon nanotubes (CNTs) were investigated using the SEM/STEM microscopy and Raman spectroscopy. The results show that the useful range of UV laser radiation fluence is narrower and the properties of synthesized CNTs depend much more on the laser fluence than in the case of infrared laser radiation.

The electrooxidation of formic acid was performed on Pd-based catalysts supported on hybrid TiO2-C materials prepared from different carbon origins by solvothermal and slurry synthesis. It has been found that carbonized hybrid TiO2-C supports with mesopore texture and high anatase:rutile ratio in the TiO2 framework led to about three times higher activity per Pd mass unit than the catalyst prepared on a commercial Vulcan XC-72 carbon black, which will allow to reduce considerably the amount of expensive noble metal at the anode of DFAFC. The conductivities of raw TiO2/C supports are several orders of magnitude lower than that for carbon Vulcan XC-72. However, the hybrid TiO2-C supports acquire high conductivity during palladium deposition. The rate of electrooxidation of formic acid on Pd/TiO2-C catalysts, calculated per one surface Pd atom (TOF), is for TOF

One of the most promising methods against drug-resistant bacteria can be surface-modified materials with biocidal nanoparticles and nanocomposites. Herein, we present a nanocomposite with silver nanoparticles (Ag-NPs) on the surface of graphene oxide (GO) as a novel multifunctional antibacterial and antifungal material. Ultrasonic technologies have been used as an effective method of coating polyurethane foils. Toxicity on gram-negative bacteria (Escherichia coli), gram-positive bacteria (Staphylococcus aureus and Staphylococcus epidermidis), and pathogenic yeast (Candida albicans) was evaluated by analysis of cell morphology, assessment of cell viability using the PrestoBlue assay, analysis of cell membrane integrity using the lactate dehydrogenase assay, and reactive oxygen species production. Compared to Ag-NPs and GO, which have been widely used as antibacterial agents, our nanocomposite shows much higher antimicrobial efficiency toward bacteria and yeast cells.

The commercial and synthesised few-layer graphene oxide, prepared using oxidation reactions, and few-layer reduced graphene oxide samples were structurally and chemically investigated by the X-ray diffraction (XRD), transmission electron microscopy (TEM) and electron spectroscopy methods, i.e. X-ray photoelectron spectroscopy (XPS) and reflection electron energy loss spectroscopy (REELS). The commercial graphene oxide (FL-GOc) shows a stacking nanostructure of about 22 × 6 nm average diameter by height with the distance of 0.9 nm between 6-7 graphene layers, whereas the respective reduced graphene oxide (FL-RGOc)—about 8 × 1 nm average diameter by height stacking nanostructure with the distance of 0.4 nm between 2-3 graphene layers (XRD). The REELS results are consistent with those by the XRD indicating 8 (FL-GOc) and 4 layers (FL-RGOc). In graphene oxide and reduced graphene oxide prepared from the graphite the REELS indicates 8–11 and 7–10 layers. All graphene oxide samples show the C/O ratio of 2.1–2.3, 26.5–32.1 at% of C sp3 bonds and high content of functional oxygen groups (hydroxyl—C OH, epoxy—C O C, carbonyl—C O, carboxyl—C OOH, water) (XPS). Reduction increases the C/O ratio to 2.8–10.3, decreases C sp3 content to 11.4–20.3 at% and also the content of C O C and C O groups, accompanied by increasing content of C OH and C OOH groups. Formation of additional amount of water due to functional oxygen group reduction leads to layer delamination. Removing of functional oxygen groups and water molecules results in decreasing the distance between the graphene layers.

In apoikogenic scorpions, growing oocytes protrude from the gonad (ovariuterus) and develop in follicles exposed to the mesosomal (i.e. hemocoelic) cavity. During subsequent stages of oogenesis (previtellogenesis and vitellogenesis), the follicles are connected to the gonad surface by prominent somatic stalks. The aim of our study was to analyze the origin, structure and functioning of somatic cells accompanying protruding oocytes. We show that these cells differentiate into two morphologically distinct subpopulations: the follicular cells and stalk cells. The follicular cells gather on the hemocoelic (i.e. facing the hemocoel) surface of the oocyte, where they constitute a cuboidal epithelium. The arrangement of the follicular cells on the oocyte surface is not uniform; moreover, the actin cytoskeleton of these cells undergoes significant modifications during oocyte growth. During initial stages of the stalk formation the stalk cells elongate and form F-actin rich cytoplasmic processes by which the stalk cells are tightly connected to each other. Additionally, the stalk cells develop microvilli directed towards the growing oocyte. Our findings indicate that the follicular cells covering hemocoelic surfaces of the oocyte and the stalk cells represent two distinct subpopulations of epithelial cells, which differ in morphology, behavior and function.

Graphene oxide was prepared from commercial graphene powder (G) platelets of 8 nm thickness by oxidation in ozone (G-O3) and low-energy (cold) glow air plasma in a pink region (G-PP). X-ray photoelectron spectroscopy (XPS) was applied for chemical characterisation of the atomic content and for obtaining quantitative information on C hybridisation. Reflection electron energy loss spectroscopy (REELS) was used for characterising the surface structure including the content of surface and bulk carbon atoms of sp 2 and sp 3 hybridisation. The G-O3 and G-PP graphene oxide samples contain a low amount of C sp 3 bonds and carbon–oxygen groups in comparison to graphene oxide prepared by the “wet” chemical methods. Oxidation of commercial graphene platelets powder, especially in air plasma, leads to increasing surface C sp 3 and significantly bulk C sp 3 contributions, indicating intercalation by oxygen groups. The intensity ratio of the REELS π + σ C sp 2 bulk to the C sp 2 surface energy loss peaks, decreasing in the order G>G-O3>G-PP, indicates exfoliation of layers in G-O3 and G-PP by oxygen functional groups and water with decreasing average number of layers in graphene oxide nanostructures due to oxidation. Although, the “wet” chemical methods are more effective for oxidation leading to a larger amount of C sp 3 and oxygen groups, the proposed methods of oxidation by ozonation and in air plasma are inexpensive, safe, effective, environmentally friendly and do not result in toxic chemical waste products.

An inventive, fast and straight-forward approach for the direct preparation of fuel cell electrodes has been developed and tested. Our approach avoids long catalyst preparation and post-synthesis treatment. It reduces the use of chemicals and thereby concomitantly lowers the environmental impact and improves cost efficiency. It combines decoration of the support by palladium nanoparticles with electrode preparation through a simple one-step ink-painting and annealing process. Composites have been investigated by high resolution transmission electron microscopy, scanning electron microscopy, and Xray diffraction. Crystalline particles are well-attached and well-distributed on the support. Particles are of few nanometers in size and spherical for decorated Vulcan whereas they are larger and irregularly shaped for decorated helical carbon nanofibers (HCNFs). Electrodes with a metal loading of 0.8 mg cm(-2) have been tested in a direct formic acid fuel cell. Both the Vulcan and the HCNF electrodes show a similar and high power output of up to 120 mW mg(-1). They also show similar performances in deactivation experiments conducted at 200 mA cm(-2) even when using only high purity grade formic acid. After deactivation the electrodes show no structural damage, making them superior to most commercial catalysts. The electrodes can be completely regenerated to initial activity by simple treatment with water. The easy regeneration process indicates that CO-adsorption on the fuel cell anode catalyst is not the main poisoning mechanism responsible for electrode degeneration.

We investigated Fe-phases of iron complexes embedded in nonfunctionalized (as-prepared) and functionalized multi-wall carbon nanotubes (MWCNTs). Mossbauer spectroscopy is a very sensitive tool to study chemical states of iron compounds embedded in MWCNTs. It showed that the chemical treatment of the as-prepared MWCNTs caused release of about 84% of iron and modification of the remaining iron compounds. In as-prepared and carboxylated MWCNTs almost 80 and 75% of iron complexes in a form of Fe3C exhibited magnetic ordering even at room temperature, respectively. In MWCNT-COONH4 only 50% of such iron compounds showed local magnetic ordering. In all cases about 2% of magnetic α-Fe fraction was detected. Through the dc magnetization and transmission electron microscopy (TEM) measurements it was proved that cementite nanoparticles formed agglomerates and their sizes were larger than 10 nm. STM measurements indicated increased homogeneity of the surface electric properties in the case of chemically treated carbon nanotubes.