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The proof-of-principle of metal recovery by using the microbial electrochemical snorkel (MES) is provided for the first time. Copper electrodes were short-circuited with the bioanodes of sediment microbial fuel cells (MFC). Two MES setups with and without separation of the compartments by proton exchange membrane (PEM) were developed and their performance was compared with that of an MFC loaded by 510 Ω external resistance. A copper removal of 97.8 ± 4.5% and 98.3 ± 4.8% was achieved for 10 days by MES with PEM and MFC, respectively, while by using MES without PEM a removal of over 95% was obtained for only 2 days. In both operation modes, Cu2O coatings were deposited on the cathodes. The highest cathodic efficiency of 61.7 ± 6.9% was achieved with the MES without PEM, while the highest copper recovery of 42.4 ± 4.9% was obtained with the MES with PEM. The regeneration of copper reached by using MES is over 10% higher than that gained by the MFC. The obtained results show the applicability of MES for water purification from copper without additional energy input.

Purpose: The aim of this study was to investigate if repeated use of pilot and depth drills for implant site preparation in combination with resterilization leads to any significant changes in cutting edges or in preparation times. Materials and methods: With drills of different lengths and widths (pilot, parallel, and tapered), osteotomies were performed under constant conditions in pig jaws. After each osteotomy, the drills were processed and sterilized. The required time for finishing the osteotomy was noted and analyzed. At the end of each osteotomy cycle, consisting of 10 osteotomies and 10 sterilizations, the cutting edge wear of the drill was analyzed using scanning electron microscopy. Unused but sterilized drills served as a control group. Results: There was no statistically significant difference in the evaluated wear between pilot drills and depth drills as well as between the test and the control group. After 60 osteotomies, implant drills showed considerable signs of wear at the major cutting edge (P > .05). Osteotomy led to a significant increase in the drilling time. While pilot drills showed an increase of drilling time of the factor 33.3, and the tapered drills of the factor 5.37, the parallel drills remained constant in their performance. Conclusion: Within the limitations of this study, it can be concluded that the process of sterilization as well as the number of performed osteotomies play a major role in the wear of the cutting edge and the performance of implant drills.

Materials with cation ratio Cu:Ni:Fe = 0.5:0.5:2 were prepared by sol-gel auto-combustion technique using corresponding metal nitrates and citric acid as complexating/fuel agent and ammonia for pH adjustment. For comparison, one sample was synthesised by the same method, but without pH adjustment, and one sample with nominal composition Cu0.5Ni0.5Fe2O4 was synthesised by co-precipitation method. The methods of X-Ray Diffraction, Mossbauer spectroscopy at room (RT) and liquid nitrogen (LNT) temperature, UV-Vis, FTIR, nitrogen physisorption, and H2-TPR were applied for structural characterization of the materials. X-Ray Diffraction and Mossbauer spectroscopy proved formation of spinel phase, Fe4-xNixN and minor quantity CuO phase. Presence of doublets with high quadrupole splitting (Δ = 1.02–1.07 mm/s) at RT Mossbauer spectra, which are partly preserved at LNT is evidenced that nitride phase has high nickel content. Specific surface of oxide/nitride samples was determined in the range 19–24 m2/g. The catalytic behaviour of the Cu-Ni-Fe- oxide/nitride materials is studied in reaction of methanol decomposition. Mossbauer spectra reveal significant phase transformations of the samples to Hagg carbide (χ-Fe5C2) and Fe,Ni-alloy under the reaction medium, which ensures good catalytic activity and selectivity to H2 and CO. The photocatalytic oxidation activity of samples was tested in degradation of Alizarin model contaminant dissolved in water under visible light and UV-C light irradiation.

International audience; The twisted structures of the chitin-based cuticle of beetles confer specific optical characteristics on them. Intrigued by the observation of Bragg gratings with a depth-dependent periodicity in the cuticle of Chrysina beetles, we determine the experimental conditions leading to their transcription into cholesteric liquid-crystal oligomers. We correlate the optical properties of reflectors thus produced with their internal morphology, as observed by transmission electron microscopy. With the use of a single parameter, thermal annealing time, the reflection color is made time-tunable. Different spectral bands and reflection colors from golden yellow to NIR are available, and the irreversibility of the final color is reached at the end. On the basis of the design concept and these properties, these hybrid chiral–achiral materials inspire the fabrication of smart reflective labels. When encapsulated in the package of a product to be kept under cold conditions, the label records the history of the product conservation. Two kinds of information based on color changes are recorded as follows: qualitative information reporting that the product was kept outside of the specified storage temperature and quantitative information giving an indication of the time elapsed since the temperature exceeded the storage temperature of the product.

This study is aimed at the development of intelligent approach for clean energy production via valorization of industrial waste by-products. The proposed scheme is based on the preparation of activated carbon based catalysts for methanol decomposition as a source of hydrogen. Peach stones from the canning industry and by-products from low-rank coals treatment, all of them widely available in the Balkan region, are used as activated carbon precursors. The specific effect of carbon support on the formation of the loaded active NixZn1-xFe2O4 (x = 0; 0.2; 0.8; 1) ferrite phase are studied by nitrogen physisorption, XRD, HRTEM, FTIR, Moessbauer spectroscopy, TPR with hydrogen and Boehm method. To precise the discussion, analogues KIT-6 silica modifications are used as reference samples. It was found that the hosted in the activated carbon metal containing phase represents a complex mixture of Ni and/or Zn substituted magnetite, NiFe alloys, metallic Fe and ZnO. Its composition and dispersion is controlled by the variation of the Ni/Zn ratio and the texture peculiarities of the carbon support, the latter being easily tuned by the waste precursor used. The NixZn1-xFe2O4 modified activated carbons obtained from peach stones and coal treatment by-products possess a significant potential for sustainable environmental protection as cheap and effective catalysts for hydrogen production.

International audience; Twisted cholesteric liquid crystal patterns are found in the iridescent chitin-containing cuticles of many insects. They may exhibit spatial variation in the helical pitch and in the orientation of the helix axis, as in the two-band, green and silver cuticle of the scarab beetle, Chrysina gloriosa, which is the focus of the present study. The silver bands are pattern-free, whereas the green bands exhibit an array of microcells. By hyperspectral microscopy with 6 nm spectral resolution in the range of 400 nm-1000 nm, we investigated the topography of twisted cuticular structures under various orientations of the helical axis, from an orientation close to the normal to the cuticle surface in the silver bands to a spatially varying orientation in the microcells. We deal with two aspects of the topography: the shape of the surface at the interface between the transparent wax layer and the chitin-protein matrix, which is a challenging task since the cuticle is covered by the wax layer preventing direct topographic measurements by standard techniques, and the features of the deep layers in the cuticle, by addressing the distribution of the helical pitch of the twisted structure at a variable depth. We demonstrate that both types of topographic information are embedded in the hyperspectral data. Specifically, we show that the spatial distribution of the spectral center of mass portrays the geometrical shape of the hexagonal microcells. Furthermore, we evidence the spectral signature of the structural patterns located at the edges of the microcells.

Materials with nominal composition Cu0.5Ni0.5Fe2O4 were prepared by sol-gel auto-combustion technique using corresponding metal nitrates and citric acid as complexating agent/fuel agent. Different ratios between citric acid and metal ions were used to control the combustion reaction. For comparison, Cu0.5Ni0.5Fe2O4 ferrite was also synthesised by co-precipitation. Mossbauer spectroscopy was used for analysis of synthesised samples both at room temperature and liquid nitrogen boiling temperature. Iron distribution in tetrahedral and octahedral positions of spinel lattice was determined. Different degrees of agglomeration of the ferrite phase were estimated by super-paramagnetic behaviour of samples. In addition, methods of X-Ray Diffraction, UV-Vis, FTIR, nitrogen physisorption, TPR with hydrogen were applied for structural characterization of the materials. Some quantities of secondary phases (Cu, Cu-Ni alloy and hematite) were found out in samples prepared by auto-combustion method. The catalytic activities of the samples in ethyl acetate oxidation reaction strongly depended on the variations in the structural and texture characteristics of the samples. The sample synthesized at the highest ratio of citric acid to metal ions is characterized by the smallest ferrite crystallite size, the higher surface area and the best catalytic activity.

Replicating biological patterns is promising for designing materials with multifaceted properties. Twisted cholesteric liquid crystal patterns are found in the iridescent tessellated cuticles of many insects and a few fruits. Their accurate replication is extremely difficult since discontinuous patterns and colors must coexist in a single layer without discontinuity of the structures. Here, a solution is demonstrated by addressing striped insect cuticles with a complex twisted organization. Geometric constraints are met by controlling the thermal diffusion in a cholesteric oligomer bilayer subjected to local changes in the molecular anchoring conditions. A multicriterion comparison reveals a very high level of biomimicry. Proof-of-concept prototypes of anti-counterfeiting tags are presented. The present design involves an economy of resources and a high versatility of chiral patterns unreached by the current manufacturing techniques such as metallic layer vacuum deposition, template embossing and various forms of lithography which are limited and often prohibitively expensive., Replicating biological patterns is promising for designing materials with multifaceted properties but replication of twisted cholesteric liquid crystal patterns found in insects is extremely difficult. Here, the authors use liquid crystal oligomers to reproduce the textural, structural and color properties of biological liquid crystals.

Biological systems inspire the design of multifunctional materials and devices. However, current synthetic replicas rarely capture the range of structural complexity observed in natural materials. Prior to the definition of a biomimetic design, a dual investigation with a common set of criteria for comparing the biological material and the replica is required. Here, we deal with this issue by addressing the non-trivial case of insect cuticles tessellated with polygonal microcells with iridescent colours due to the twisted cholesteric organization of chitin fibres. By using hyperspectral imaging within a common methodology, we compare, at several length scales, the textural, structural and spectral properties of the microcells found in the two-band cuticle of the scarab beetleChrysina gloriosawith those of the polygonal texture formed in flat films of cholesteric liquid crystal oligomers. The hyperspectral imaging technique offers a unique opportunity to reveal the common features and differences in the spectral-spatial signatures of biological and synthetic samples at a 6-nm spectral resolution over 400 nm–1000 nm and a spatial resolution of 150 nm. The biomimetic design of chiral tessellations is relevant to the field of non-specular properties such as deflection and lensing in geometric phase planar optics.

The manufacturing of double curved surfaces in architecture is a time consuming and laborious process. There are many ways to fabricate double curved surfaces, however, most of these approaches require special molds, which is expensive for individual production. To create freeform surfaces from planar sheet materials, several design-to-fabrication strategies based on bending and forming processes have been developed in the past few years. Such strategies are based on certain mechanical or geometrical properties of the material, such as elasticity or thickness. In this research we focus on investigating design for the purpose of manufacturing double curved architectural panels, based on geometry and material processing. We propose a cost-efficient design-to-fabrication approach based on kerf bending, a manufacturing strategy which bends materials using a series of cuts called ‘kerfs’, to form planar sheet materials, often used in standard construction. Planar sheet materials, such as wood based or gypsum boards which can be applied in such a fabrication strategy, are widely used for interior wall finishing. For testing and evaluating this approach a full scale double curved panel is fabricated.

Introduction: Patients with advanced bone resorption, non-resilient mucosa or presence of exostoses, require specific methods of prosthetic treatment with complete or partial dentures, namely the use of soft materials for lining. Their porous structure is a prerequisite for bacterial and fungal colonization, that creates conditions for the occurrence of denture stomatitis. The purpose of the present in vivo study is to explore the species and quantity of Candida spp. in the saliva of patients with complete dentures lined with two types of silicone-based elastic materials after a six-month period of observation. Material and methods: The research was conducted upon 45 completely edentulous patients at the age from 48 to 90 (67,9 ± 9,99 years on the average). They were divided into three groups (A, B, C). For the identification and quantity assessment of the presence of Candida spp. in saliva, the researchers used Chrom agar Candida (BioMerieux) and MALDI TOF spectrophotometric analysis – VITEK MS (BioMerieux). Results: The screening of the patients before denture delivery demonstrated absence of Candida spp. in the saliva of 44.4% and Candida albicans – 24.4%. After denture delivery, on the third and the sixth month, we found an increased quantity of C.tropicalis in the patients of groups A and B. In the saliva of the patients with denture stomatitis, the predominantly present species was C.tropicalis (54%) isolated in quantities over 104 CFU/ml. Conclusion: The presence of C. tropicalis in the saliva related to this type of treatment is a prerequisite for the development of hard-to-treat candidoses.

Copper-manganese ferrites with nominal compositions Cu 1-х Mn х Fe 2 O 4 , where x = 0; 0.2; 0.4; 0.6; 0.8 and 1 are synthesized by sol-gel auto-combustion method. Formation of ferrites with cubic spinel structure and crystallite size of 11–26 nm was observed. A decrease of iron located in tetrahedral positions with the increase of Mn content in ferrite structure was found. The prepared ferrite materials are tested as catalysts in water-gas shift reaction (WGSR) and methanol decomposition (MD). The samples are arranged according the WGS activity in following order: Cu 0.8 Mn 0.2 Fe 2 O 4 > Cu 0.5 Mn 0.5 Fe 2 O 4 > CuFe 2 O 4 > Cu 0.2 Mn 0.8 Fe 2 O 4 > MnFe 2 O 4 . All mixed copper-manganese ferrites exhibit higher catalytic activity in methanol decomposition as compared to single CuFe 2 O 4 and MnFe 2 O 4 ones. A significant phase transformation with ferrites under the reduction reaction medium which influences the formation of real catalytic active phase is registered. Formation of magnetite or Mn-substituted magnetite is registered during the WGSR, while iron carbides and Mn-rich oxides are the dominant phases during the MD reaction.

The cholesteric liquid crystal (CLC) phase exhibits a helical structure with a twist axis perpendicular to the local molecular director [1]. Because of the periodic change in refractive index, CLC exhibit 1-D photonic bandgap characteristics, through selective polarization-dependent Bragg reflection. These optical properties open some interesting prospects for dispersion management, for instance slow light or ultrafast laser modulation [2]. The experimental demonstration of femtosecond pulse compression has been recently proposed, thanks to the combination of a thick and highly birefringent CLC with a strong nonlinearity [2].

The cholesteric liquid crystal (CLC) phase exhibits a helical structure with a twist axis perpendicular to the local molecular director. When light propagates in the Bragg regime through a CLC slab with a planar texture, the medium gives rise to Bragg reflection, selective in wavelength and in polarization. The characteristics of the Bragg band are tunable by acting on the following structural parameters: the pitch, the helicity sense and the helix orientation. Tuning the latter parameter produces polygonal textures (Fig. 1, center). Such a texture is made of an array of micrometer-scale polygonal cells, acting a network of microlenses with wavelength-tunable focusing properties [1]. Polygonal textures can be found in biological CLCs (for instance, multiwavelength micromirrors the cuticle of scarab beetle Chrysina gloriosa [2]).

International audience; Ongoing research on chiral liquid crystals takes advantage of the peculiar behavior of twisted structures subject to curvature. We demonstrate the fine tunability of the characteristics of the bandgap of a cholesteric structure in which the orientation of the helix axis spatially changes. To date, the spectral resolution of the order of 6 nm, herein reached by hyperspectral imaging, has not been solved in tilted helices. A correlation between spectral shifts and spatial twists is thus made possible.

International audience; We demonstrate the ability to manipulate ultrashort pulses in cholesteric liquid crystals in the linear regime. We present an extensive analysis of the spectral changes undergone by 20fs pulses when propagating through band edges of cholesteric liquid crystals. The accurate quantification of the introduced optical dispersion opens the way to controlled stretching and compression of ultrashort pulses. The behaviors of cholesteric liquid crystal films with different thickness, bandgap and structural parameters (monotonic pitch versus pitch-gradient films) are compared. A statistical approach is disclosed to fidelize and deepen the set of experimental investigations.

The development of cost-effective cathodes, operating at neutral pH and ambient temperatures, is a crucial challenge for the practical application of microbial electrolysis cell (MEC) technology. In this study, NiW and NiMo co-deposits produced by electroplating on Ni-foam are explored as cathodes in MEC. The fabricated electrodes exhibit higher corrosion stability and enhanced electrocatalytic activity towards hydrogen evolution reaction in neutral electrolyte compared to the bare Ni-foam. NiW/Ni-foam electrodes possess six times higher intrinsic catalytic activity, estimated from data obtained by linear voltammetry and chronoamperometry. The newly developed electrodes are applied as cathodes in single-chamber membrane-free MEC reactors, inoculated with wastewater and activated sludge from a municipal wastewater treatment plant. Cathodic hydrogen recovery of 79% and 89% by using NiW and NiMo cathodes, respectively, is achieved at applied voltage of 0.6 V. The obtained results reveal potential for practical application of used catalysts in MEC.

To increase the efficacy of radiation, iron oxide nanoparticles can be utilized for their ability to produce reactive oxygen species (ROS). Radiation therapy promotes leakage of electrons from the electron transport chain and leads to an increase in mitochondrial production of the superoxide anion which is converted to hydrogen peroxide by superoxide dismutase. Iron oxide nanoparticles can then catalyze the reaction from hydrogen peroxide to the highly reactive hydroxyl radical. Therefore, the overall aim of this project was to utilize iron oxide nanoparticles conjugated to a cell penetrating peptide, TAT, to escape lysosomal encapsulation after internalization by cancer cells and catalyze hydroxyl radical formation. It was determined that TAT functionalized iron oxide nanoparticles and uncoated iron oxide nanoparticles resulted in permeabilization of the lysosomal membranes. Additionally, mitochondrial integrity was compromised when A549 cells were treated with both TAT-functionalized nanoparticles and radiation. Pre-treatment with TAT-functionalized nanoparticles also significantly increased the ROS generation associated with radiation. A long term viability study showed that TAT-functionalized nanoparticles combined with radiation resulted in a synergistic combination treatment. This is likely due to the TAT-functionalized nanoparticles sensitizing the cells to subsequent radiation therapy, because the nanoparticles alone did not result in significant toxicities.

The aim of the current investigation is to follow the formation of iron phase in mesoporous nanocrystalline titania and Hf-doped titania powders and its influence on the physicochemical and catalytic properties of the obtained materials. The parent host matrices were synthesized by using either template-assisted hydrothermal approach or homogeneous precipitation with urea. The iron modifications were prepared by incipient wetness impregnation with Fe(NO3)3.9H2O. Nitrogen physisorption, X-ray diffraction, TEM analysis, Moessbauer spectroscopy, UV–Vis spectroscopy and TPR with hydrogen were the techniques used for samples characterization and their catalytic behaviour was studied in methanol decomposition and ethyl acetate oxidation as catalytic tests. The hydrothermal treatment, the iron modification and the doping with Hf lead to the appearance of a significant absorption in the visible region for the studied samples, which together with the red shift of the absorption edge could be advantageous because of increased yield of photogenerated electron–hole pairs. The presence of very highly dispersed and uniform iron oxide particles with sizes below 4 nm and superparamagnetic behaviour are most beneficial for the catalytic activity in ethyl acetate total oxidation. On the other hand, the iron introduction retards the methanol conversion by blocking some of the supports active sites and alone or together with Hf changes the selectivity to predominant methane formation.

This paper presents a roughness measurement of zirconia ceramics, widely used for dental applications. Surface roughness variations caused by the most commonly used dental instruments for intraoral grinding and polishing are estimated. The applied technique is simple and utilizes the speckle properties of the scattered laser light. It could be easily implemented even in dental clinic environment. The main criteria for roughness estimation is the average speckle size, which varies with the roughness of zirconia. The algorithm used for the speckle size estimation is based on the normalized autocorrelation approach.

Over the past decade, anodic aluminium oxide (AAO) has become one of the most widely used materials as a platform for developing new types of devices in micro- and nanotechnology. Due to the potential use of highly ordered honeycomb porous AAO membranes in many engineering applications, considerable attention is being paid to the mechanical characterization of such thin films. In this study, the mechanical properties and deformation behavior of a nanoporous alumina film were investigated by nanoindentation. AAO films with an average pore diameter of 40 nm were fabricated electrochemically. The morphology and the mechanical properties of AAO were studied using scanning electron microscopy and nanoindentation, respectively. The force-displacement dependences obtained revealed that in the case of a freestanding AAO membrane the sample demonstrates extremely high elasticity. The indentation modulus and the hardness were found to decrease nonlinearly with an increase in the applied force.

International audience; The carapace of insects can generate optical information with vivid structural colors, which may be of paramount importance in the life and the evolution of most day-living animals. A cholesteric liquid crystal organization of chitin fibrils is recurrently at the origin of optical properties. We summarize some recent results on the carapace of scarab beetles with possible functions related to optical information and thermoregulation. In the case of Chrysina gloriosa, green bands include wavelength-selective micromirrors and silver stripes play the role of flat metallic reflector operating over the visible spectrum and into the NIR-IR spectrum. Bio-inspired materials might address broadband reflectors for energy savings, stealthiness, cryptography or wavelength-specific light modulators in routing technologies.

Twisted liquid-crystalline organizations are ubiquitous in living matter [1] , [2] . Many insects own a tessellated carapace with bumps, pits, indentations, stripes or spots ( Fig. 1 ). These geometric variation often exhibit iridescent colors, which are the consequence of a complex twist of chitin macromolecules. Such optical information with vivid structural colors might be of paramount importance in the life and the evolution of most day-living insects. Many biological functions are yet debated. They are related to conspecific or intra-species communication, thermoregulation, camouflage, survival or navigation [1] , [3] . For example, the cuticle of the scarab beetle Chrysina gloriosa exhibits two bands ( Fig. 2 ). The green band serves as a wavelength-selective (green) diffuser due to the set of polygons arranged on a curved surface and, at the mesoscopic scale, it behaves as an array of wavelength-selective micromirrors [4] . The silver stripe plays the role of a flat metallic reflector operating over the visible spectrum and into the infrared spectrum [4] . The orientation of the helicoidal structure varies in green stripes ( Fig. 3 ), whereas it is fixed in silver stripes. The outermost part of insect cuticles is very often covered with wax, which restricts water loss, prevents desiccation, may lend superhydrophobic and self-cleaning properties to the cuticle, and serves for chemical communication in many species. While cuticular waxes are considered isotropic, the wax layer of the cuticle of C. gloriosa exhibits an intriguing nanoscale laminate texture, as revealed by electron microscopy of the transverse sections [5] . Micro-textured cuticles of scarabs may inspire researchers and engineers to make their replicas as optical materials. Potential applications are in the field of wavelength-specific light modulators in routing technologies, broadband reflectors for energy savings, coatings for cryptography purposes (wavelength-dependent and polarization-dependent micro- and nanoscale patterns), camouflage (suits with a broad reflection in the IR spectrum identical to the one of the background) or thermoregulation for buildings.

Ordered mesoporous silica of SBA-15 type and activated carbon, prepared from waste biomass (peach stones), are used as host matrix of nanosized iron and cobalt particles. The effect of preparation procedure on the state of loaded nanoparticles is in the focus of investigation. The obtained materials are characterized by Boehm method, low temperature physisorption of nitrogen, XRD, UV–Vis, FTIR, Mossbauer spectroscopy and temperature programmed reduction with hydrogen. The catalytic behaviour of the samples is tested in methanol decomposition. The dispersion, oxidative state and catalytic behaviour of loaded cobalt and iron nanoparticles are successfully tuned both by the nature of porous support and the metal precursor used during the samples preparation. Facile effect of active phase deposition from aqueous solution of nitrate precursors is assumed for activated carbon support. For the silica based materials the catalytic activity could be significantly improved when cobalt acetylacetonate is used during the modification. The complex effect of pore topology and surface functionality of different supports on the active phase formation is discussed.

Nanocrystalline copper–cobalt ferrites with composition Cu1−x Co x Fe2O4, where x = 0.2 and 0.8, were synthesized by mechanochemical treatment of co-precipitated precursors. The ferrite powders were characterized by XRD and Mossbauer spectroscopy. Results proved obtaining of spinel ferrites with crystallite size smaller than 10 nm. Increasing of crystallite size of samples with increasing of mechanochemical treatment duration was established, too. Catalytic properties of obtained ferrites were tested in reactions of oxidation of CO, methanol and dimethyl ether. High catalytic activity of nanocrystalline copper–cobalt ferrites toward CO and CH3OH (about 100% conversions of CO and CH3OH at 160 °C) and moderate activity toward (CH3)2O oxidation were established. The results obtained revealed that the Co/Cu atomic ratio is an important factor determinant the behavior of catalysts toward methanol and DME oxidation.

A comparison between highly neutron irradiated samples from the region of weld № 4 and low irradiated samples from weld № 1 taken from the pressure vessel of the WWER-440 Unit № 1 of the Kozloduy NPP has been performed. Measurements of the residual activity of samples from the outer surface of the reactor pressure vessel bottom corpus reveal very low activity of 60Co. Insofar as there the base and weld metal appear to be exposed to a very low neutron fluence, the samples from these locations can be considered as practically not affected and may serve as a reference basis for comparison with highly irradiated pressure vessel regions. The Mossbauer parameters isomer shift (IS) and quadrupole splitting (QS) were found to be absolutely irradiation insensitive. A stepwise reduction of the internal hyperfine magnetic field Bhf, each by about 2.6 T, was observed. This can be attributed to the replacement of one or two surrounding iron atoms as first nearest neighbors by non-iron alloying atoms. The Mossbauer experimental line widths for irradiated and non-irradiated samples are practically the same, which is a quite unexpected result. The area fraction ratio for the three main Zeeman sextet subspectra S1:S2:S3 shows very high irradiation sensitivity. For the bottom low irradiated region of the reactor vessel the values are S1:S2:S3 = 50.1:40.0:9.4. After seven years of operation between the pressure vessel annealing in 1989 and the autumn of 1996 when the samples from weld № 4 were taken the ratio changes strongly to S1:S2:S3 = 56.4:34.7:8.5. A possible explanation of this result is that neutron irradiation gives rise to a precipitation process involving predominantly alloying atoms as Ni, Mn, Cr, Mo and V which become mobile and precipitate in the form of carbides and/or P-rich phases and alloying atom aggregates. This “refinement” process lowers the partial area of subspectra S2 and S3 where alloying atoms are involved and leads to a higher area fraction of the pure iron component S1, which is the major experimental result. For a more complete Mossbauer investigation on the processes of generation of structure defects caused by the neutron fluence, a new series of measurements will be performed by using a set of so-called surveillance specimens with different irradiation histories which are available only for the WWER-1000 reactors of the Kozloduy NPP.

The present work aims to evaluate the influence of synthesis conditions and gold addition on structural and functional characteristics of copper-manganese ferrites. Object of the investigation is spinel ferrite with composition Cu0.5Mn0.5Fe2O4, thermally treated at different conditions. The influence of gold deposition on structure of ferrites and catalytic properties in water-gas shift reaction (WGSR) is studied on the ferrite sample obtained at 300 ∘C. Structural characteristics of samples are determined by Mossbauer spectroscopy and X-Ray diffraction. The Mossbauer spectra of treated at different temperature ferrite samples consist of sextet and doublet components. A comparative assessment of crystallite size of ferrite phase was accomplished from the calculated value of the hyperfine fields. It was established well expressed tendency of ferrite crystallite growth with increasing of thermal treatment temperature. Increasing of the ferrite crystallite size in presence of gold in the sample is established, too. The analysis of catalytic activity in WGSR shows unexpected result i.e. the activity of gold-modified ferrite sample is lower than that of the sample without gold. Probably this is due to complex factors, including recrystallization of the ferrite phase due to additional thermal treatment at higher temperature, addition of gold, changes of the structural features and phase composition during catalytic test.

A combination of thermal and mechanical (high energy ball milling) treatment was applied in an attempt to obtain polycrystalline mixed metal binary and ternary oxides of the type Co x Zn 1-x Fe 2 O 4 (x=0; 0.25; 0.5; 0.75; 1). The synthetic procedure used successfully produced single-phased, homogeneous ZnFe 2 O 4 , CoFe 2 O 4 , and Co 0.75 Zn 0.25 Fe 2 O 4 , as well as mixed oxides, whose composition depended both on the duration of the high energy ball milling and the ratio Zn(II)/Co(II). The formation of spinel-like structures was proved by XRD, Mossbauer spectroscopy and Raman spectroscopy. For the characterization of the samples low-temperature N 2 adsorption, UV/Vis spectroscopy and transmission electron microscopy were applied. The energy band gap of the samples was calculated, suggesting they are promising photocatalysts. The decomposition of the Malachite Green in model water solutions under UV-light irradiation was successfully achieved in the presence of the samples as photocatalysts. The highest rate constant was obtained for the sample synthesized at longer milling time in combination with higher Zn(II)/Co(II) ratio. The photocatalytic activity of the ternary mixed oxides was compared with the pure hematite, α-Fe 2 O 3 , and the binary ZnFe 2 O 4 and CoFe 2 O 4 ferrites with spinel structure that were treated in the same way. A synergetic effect of α-Fe 2 O 3 and the spinel-like structure on the photocatalytic properties of ternary mixed metal oxide was detected.

High quality micro-mesoporous activated carbon was prepared from waste bio-mass (peach shells) and used as a host matrix of cobalt ferrite nanoparticles. The obtained materials were characterized by N 2 physisorption, XRD, FTIR and Moessbauer spectroscopy and tested as catalysts for hydrogen production from methanol. Depending on the Co/Fe ratio formation of pure CoFe 2 O 4 or a mixture of CoO and ferrite phases were observed for carbon supported bi-component materials, while under the same condition the silica support provides the formation of non-stoichiometric ferrite phase. The catalytic active phase which is formed by the influence of the reaction medium represents a complex mixture of non-changed ferrite, magnetite, Co–Fe alloy and/or Fe 3 C in different proportions.

The effect of the transverse motion behavior on contact heat transfer was experimentally investigated in an indirectly heated batch rotary drum. Inside the drum, one rotating and one stationary measuring rod were installed, each assembled with 16 K-type thermocouples to measure temperatures. Thus, the radial and circumferential temperature gradients within the solid bed were measured, and the contact heat transfer was determined. As test materials, quartz sand, alumina, and cement powder were used, and the parameters filling degree (10–20%) and rotational speed (1–6 rpm) were varied.

Activated carbons were prepared from waste coal treatment by-products by different preparation and activation procedures and applied as a host matrix of nanodispersed cobalt and iron species. Thus obtained composites were characterized by nitrogen physisorption, XRD, UV–Vis, FTIR, TPR and tested as catalysts in methanol decomposition to hydrogen and CO. It was established that the activated carbon, prepared from waste coal treatment by-products could be successfully used for the preparation of highly active catalysts for methanol decomposition. The facilitated effect of surface functionality decrease on the dispersion and catalytic activity of loaded metal species was demonstrated.

The aim of presented paper was to study preparation of catalytic materials for water purification. Iron oxide (Fe3O4) samples supported on activated carbon were prepared by wet impregnation method and low temperature heating in an inert atmosphere. The as-prepared, activated and samples after catalytic test were characterized by Mossbauer spectroscopy and X-ray diffraction. The obtained X-ray diffraction patterns of prepared samples show broad and low-intensity peaks of magnetite phase and the characteristic peaks of the activated carbon. The average crystallite size of magnetite particles was calculated below 20 nm. The registered Mossbauer spectra of prepared materials show a superposition of doublet lines or doublet and sextet components. The calculated hyperfine parameters after spectra evaluation reveal the presence of magnetite phase with nanosize particles. Relaxation phenomena were registered in both cases, i.e. superparamagnetism or collective magnetic excitation behavior, respectively. Low temperature Mossbauer spectra confirm this observation. Application of materials as photo-Fenton catalysts for organic pollutions degradation was studied. It was obtained high adsorption degree of dye, extremely high reaction rate and fast dye degradation. Photocatalytic behaviour of a more active sample was enhanced using mechanochemical activation (MCA). The nanometric size and high dispersion of photocatalyst particles influence both the adsorption and degradation mechanism of reaction. The results showed that all studied photocatalysts effectively decompose the organic pollutants under UV light irradiation. Partial oxidation of samples after catalytic tests was registered. Combination of magnetic particles with high photocatalytic activity meets both the requirements of photocatalytic degradation of water contaminants and that of recovery for cyclic utilization of material.

Copper zinc ferrites (Cu1−xZnxFe2O4) with different composition (x = 1; 0.2; 0.5; 0.8) were prepared by conventional thermal method. Formation of well crystallized ferrite phase with cubic structure and crystallites size of about 19.08–24.39 nm was observed by Powder X-ray diffraction and Mossbauer spectroscopy. The ferrite materials were tested as catalysts in methanol decomposition to CO and H2. A strong dependence of the catalytic behaviour of Cu1−xZnxFe2O4 ferrites of their composition and the phase transformations which occurred under the reaction medium was established.

Two series of Cu0.5Co0.5Fe2O4 ferrites were obtained by thermal or mechanochemical treatment of hydroxide carbonate precursor. The effect of the annealing temperature and the milling time, respectively, on the formation of the mixed ferrite phase was studied by DSC, XRD, Mossbauer spectroscopy and TPR with hydrogen. The catalytic behavior of the samples was tested in methanol decomposition to CO and H2. The initial phase composition of the obtained ferrites and the formation of the catalytic active phase under the reaction medium could be controlled by the preparation procedure used.

The paper reports results from Langmuir probe current-voltage (IV) characteristic measurements in argon and oxygen low-gas-pressure magnetized plasma. The plasma was produced in a stainless steel discharge tube with length 1.5 m and diameter 0.17 m with a hot filaments cathode. The wall of the discharge tube was grounded. An axial magnetic field B was created by a solenoid. A platinum cylindrical Langmuir probe with radius R = 5· 10−5 m and length L = 5· 10−3 m was placed axially and radially at the center of the discharge tube in order to perform measurements along and across the magnetic field. Using the second derivatives of the measured IV probe characteristics, the EEDF in argon and oxygen was evaluated. The derivatives were taken numerically. Measurements in an argon (i.e., in the absence of negative ions) were performed to obtain results for comparison with the measurements in an oxygen gas discharge, where a high density of negative ions is expected. In the measurements of the second derivatives of the IV characteristics with the probe parallel to the magnetic field in oxygen, a peak appears close to the plasma potential due to the registration of negative ions. In the same time, the electron part of the second derivative was substantially suppressed relatively to the case with the probe oriented perpendicular to the magnetic field. Thus using the appropriate orientation of the probe and a low magnetic field, when the electron part of the second derivative is suppressed, since the negative ion part is not affected by the low magnetic field applied, we can evaluate precisely the negative ion density. The results from the plasma parameters evaluation (plasma potential, electron and negative ion densities and electron temperatures) are presented and discussed (© 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Six types of stainless steels (SS) were studied for changes in its structure and magnetic properties under mechanical treatment. Depending on intensity and duration of the process of plastic deformation and the SS type the paramagnetic austenite structure transforms partially to completely into ferrite structure with ferromagnetic behaviour. Some of the SS tested were found slightly modified yet in the process of its manufacturing. Only one SS type with high Ni content preserved its structure and paramagnetic properties even after very intense mechanical treatment.

Spinel ferrites with nominal composition Cu 0.5Mn 0.5Fe 2 O 4 and different distribution of the ions are obtained by auto-combustion method. Mossbauer spectroscopy, X-ray Diffraction, Thermogravimetry-Differential Scanning Calorimetry, Scanning Electron Microscopy and catalytic test in the reaction of methanol decomposition is used for characterization of synthesized materials. The spectral results evidence that the phase composition, microstructure of the synthesized materials and the cation distribution depend on the preparation conditions. Varying the pH of the initial solution microstructure, ferrite crystallite size, cation oxidation state and distribution of ions in the in the spinel structure could be controlled. The catalytic behaviour of ferrites in the reaction of methanol decomposition also depends on the pH of the initial solution. Reduction transformations of mixed ferrites accompanied with the formation of Hagg carbide χ-Fe 5 C 2 were observed by the influence of the reaction medium.

The spinel-type ferrites NiFe2O4 and Zn0.5Ni0.5Fe2O4 modified by lanthanide ions Eu3+ and Tb3+ were prepared by a sol—gel process with propylene oxide as a gelating agent. The phase homogeneity of the samples was tested by XRD and Mossbauer spectroscopy. Transmission electronic microscopy used for characterisation of the morphology of the samples revealed nanosized powdered samples with a narrow distribution of particle sizes. It was noted that the presence of Ln3+ ions influenced the magnetic properties of nanosized NiFe2O4 and Ni0.5Zn0.5Fe2O4 ferrites. The dependence of the magnetic properties of the samples on the rare-earth doping may be explained by the different grain sizes. The saturation magnetisation tends to decrease with increasing rare-earth doping and decreasing crystallite size. A similar trend was observed for the coercive field, with the exception of the Tb3+-doped Zn0.5Ni0.5Fe2O4 where it remained the same as in the pure ferrite.

The heat transfer by contact between the covered inner wall surface and the solid bed in a rotary drum was experimentally investigated. An indirectly heated batch rotary drum with a diameter of D =600 mm and a length of L =450 mm has been used. Inside the drum, a rotating and stationary measuring rod was installed, each assembled with 16 k-type thermocouples to measure the temperatures. Thus, the radial and circumferential temperature gradients within the solid bed were measured, and the contact heat transfer was determined from the heating of the bed. The operating parameters, rotational speed and filling degree of the drum were varied in the range of n =1, 3, 6 rpm and F =10, 15, 20% and the effect on the contact heat transfer coefficient was estimated. Quartz sand with a mean particle diameter of d P =0.2 mm was used as the testing material. The measured heat transfer coefficients were compared with theoretical calculations of four model approaches from the recent literature. A good agreement between the measurements and three model approaches could be achieved.

The aim of this in vitro study was to evaluate the influence of different finishing procedures on the wear behavior of zirconia against natural enamel.64 quadratic specimens (10 mm × 10 mm × 2 mm) were cut from a commercial hipped dental Y-TZP ceramic. Four different groups with 16 specimens each were formed according to the following finishing procedures: PZ (polished), RR (fine-grit diamond), GR (coarse-grit diamond), GZ (glazed). Polished specimens of a leucite-reinforced glass ceramic (Empress CAD) were used as a control (GC). The materials were subjected to the Ivoclar wear method (Willytec chewing simulator, 120,000 cycles, 5kg weight) with 80 natural caries-free cusps of first upper molars as antagonists. Wear was analyzed for both the enamel cusps and test specimens by measurement of the vertical substance loss with a laser scanner. Surface roughness was measured by means of a white-light interferometer.The surface roughness was significantly different among the polished, diamond-finished, and glazed ceramic specimens (ANOVA, post hoc Bonferroni p0.05). The results of the one-way ANOVA indicated that the finishing technique significantly affected enamel wear (p0.05). The post hoc test indicated that the specimens finished with the coarse diamond caused significantly higher antagonist wear than the polished ones. Polished zirconia showed the lowest wear of the antagonist enamel, with a mean value of 171.74 (SD = 121.68), and resulted in enamel wear that was not significantly different from that of the glass ceramic control group. No significant linear correlation could be found between pre-testing surface roughness and abrasive wear.If zirconia is used without veneering material for crowns and fixed dental prostheses (FDPs), the surface must be well-polished if occlusal adjustments with coarse diamonds are performed. The polishing step reduces the wear of the opposing enamel.

Experimental study of the behaviour of the shape of vesicles with long tubular protrusions (tethers), connected to them in non-symmetrical isoosmolar and non isoosmolar environment was performed. I...

The improvement of the electron transfer from the microorganisms to the anode is considered to be one of the most important factors for increasing the biofuel cell efficiency. In our recent study, a significant improvement of the yeast-biofuel cell output was achieved by application of Ni-modified carbon felt anodes. In this study, the electrocatalytic properties of new nanomodified carbon materials were investigated. Nickel–iron and nickel–iron–phosphorous nanostructures were electrodeposited on carbon felt by means of pulse plating technique. The produced materials were analyzed for cytotoxicity and applied as anodes in a double-chamber mediatorless yeast-biofuel cell. The use of all modified electrodes resulted in increase of the biofuel cell outputs in comparison with those obtained with non-modified carbon felt; however, higher maximum power density values, exceeding up to 5-folds that of the control, have been achieved with NiFeP-carbon felt anodes. The observed electrocatalytic effects were connected with the particular elemental content, size distribution, and morphology of modified materials as well as with a hypothesis for switching on adaptive mechanisms as a response to Ni and Fe presence, resulting in facilitated electron transfer across the cell membrane.

Gold catalysts supported on ceria doped with FeOx were studied. The mixed supports were synthesized by two methods: co-precipitation (CP) or mechanochemical activation (MA). Depending on the preparation method, the structure of the mixed supports was different: using CP, only a Fe-modified ceria phase exists, while supplementary to ceria, a second hematite phase presents in the case of MA preparation. The reduction behavior of the gold catalysts and the initial supports was commented on the basis of hydrogen consumption and kinetic parameters of the individual reduction process. Their assignment was proposed using also the data of Mossbauer measurements. It was established that the existing separate Fe-containing phase could participate in a redox process at relatively low temperatures (LTs) and it could be promising for improvement of the catalytic performance of the mechanochemically prepared gold catalyst.

Objectives The aim of this study was to evaluate the mechanical properties and the subcritical crack growth behavior of a presintered dental Y-TZP (Kavo Everest ZS) and a hot isostatic pressed Y-TZP (Kavo Everest ZH) and to perform life data analysis. Methods For each material 150 bending bars were produced. The initial fracture strength was determined in a four-point bending test. The subcritical crack growth parameters n and A were determined in a dynamic fatigue method at four decreasing loading rates from 110 MPa/s to 0.11 MPa/s in distilled water at 38 °C. For each loading rate Weibull statistics were performed and the Weibull moduli m and characteristic strengths σ 0 were calculated. Using these data, strength–fracture probability–life time (SPT) predictions were derived for 1 day, 1 year, 5 years and 10 years, based on a static crack growth mechanism. Results The “hipped” Y-TZP ceramic exhibited a higher initial strength ( σ c = 1618.18), characteristic strength ( σ 0 = 837.15) and fracture toughness ( K IC = 4.52 MPa/m 1/2 ) than the pre-sintered ceramic ( σ c = 1431, σ 0 = 745.46 and K IC = 3.17 MPa/m 1/2 , respectively). Fatigue parameters, n and A , were 28.5 and 7.97 × 10 −24 for Everest ZH and 30.15 and 5.47 × 10 −20 for Everest ZS. The predicted fracture stress at 5% failure probability for a lifetime of 10 years was 259.34 MPa for Everest ZH and 263.2 MPa for Everest ZS. Conclusions Although the “hipped” Y-TZP showed favorable initial mechanical properties, no significant difference could be found in the susceptibility of both ceramics to subcritical crack growth and their long-term strength.

Nanodimensional powders of cubic copper ferrite are synthesized by two-steps procedure of co-precipitation of copper and iron hydroxide carbonates, followed by mechanochemical treatment. X-ray powder diffraction, Mossbauer spectroscopy and temperature-programmed reduction are used for the characterization of the obtained materials. Their catalytic behavior is tested in methanol decomposition to hydrogen and CO and total oxidation of toluene. Formation of nanosized ferrite material is registered even after one hour of milling time. It is established that the prolonging of treatment procedure decreases the dispersion of the obtained product with the appearance of Fe 2 O 3 . It is demonstrated that the catalytic behavior of the samples depends not only on their initial phase composition, but on the concomitant ferrite phase transformations by the influence of the reaction medium.

Powdery NiFe2O4 has been obtained by mechanothermal treatment. Nickel and iron hydroxides are used as initial compounds. For comparison the initial compounds are calcinated without mechanical treatment (samples obtained by direct heating). The characterization of the samples is carried out by XRD analysis and Mossbauer spectroscopy. It is established that single phase NiFe2O4 is formed after mechanical activation (5 h) and calcination at 773 K. The ferrite synthesized at this temperature contains a smaller quantity of Fe3+ ions in tetrahedral position (31%) than is the case of conventional nickel ferrite (50%). The number of tetrahedrally coordinated iron ions increases with enhancement of the synthesis temperature, approaching the distribution of the tetrahedral and octahedral positions typical of conventional NiFe2O4. The samples obtained by direct heating contain unreacted NiO and α-Fe2O3 even after calcinations at 1073 K.

In this study, a methodology for electrodeposition of nickel nanostructures on carbon felt was developed on the base of pulse plating technique. Different in size, shape, and distribution, Ni-island nanostructures were deposited varying the potential, current, pulse duration, and cycle reiteration. The biocompatibility and nontoxicity of the newly created materials toward Candida melibiosica yeast cells was proven. The prepared Ni-nanomodified carbon felts were investigated as anodes in a two-chamber mediatorless yeast−biofuel cell. Maximum power density values of 720 and 390 mW/m2 were achieved with the electrodes modified under galvanostatic and potentiostatic conditions, respectively, against 36 mW/m2 for the nonmodified ones. The better biofuel cell performance obtained with the Ni-modified electrodes is assigned to an improved electron transfer.

Nanosized copper ferrites were prepared by thermal method from the corresponding hydroxide carbonate precursors varying the temperature of synthesis. The phase composition of the obtained materials was characterized by XRD, Mossbauer spectroscopy, DSC and TPR analysis. Their catalytic properties were tested in total oxidation of toluene and methanol decomposition to CO and hydrogen. The relation between the synthesis parameters, phase composition of the samples and their transformation under the oxidation or reduction reaction medium was investigated in turns to understand the catalytic behavior of the obtained materials.