Effect of Rutile on Modulus of Rupture in Ceramic Glaze

The study was focused on the performance of rutile addition in glaze composition for antibacterial application. Rutile powder in micro size (ξηзm) were added in the glaze composition at different weight percentage (5 wt%, 7 wt%, 9 wt%, 10 wt% and 15 wt%). Glazing was performed by dipping technique for 10 seconds. Glazed tile was then sintered at 1200 °C for 1 hour. Characterizations used to observe the properties of produced tiles were physical observation, scanning electron microscopy (SEM) and modulus of rupture. Results show that cracking occurred in glazed tile which could be related to the viscosity of the glaze mixture during dipping. The relation between viscosity and the occurrence of crack depend on the amount of rutile The amount of crack appearance increases with increasing glaze viscosity. However, modulus of rupture increased when the tile was glazed.     

Preparation of CoNi high surface area porous foams by substrate controlled electrodeposition

We demonstrate that nanofabrication of 3D dendritic CoNi alloy foams with an open porous structure can be achieved by electrodeposition onto a single-crystalline Cu(111) substrate at ambient conditions. The very low wettability of this substrate caused by its low surface energy allows tailoring the CoNi deposit morphology. This is concluded from a comparison of polycrystalline Cu substrates with single-crystalline ones of different orientations. The advantages of the present CoNi alloy foams are low internal stresses and good mechanical stability on the substrate. In a second step, by comparing the catalytic properties of the achieved foam with those of CoNi layers obtained on polycrystalline Cu substrates, it is shown that the morphology of the CoNi layers has a decisive influence on the kinetics of the surface redox reaction. The higher reaction rate makes the open foam suitable as catalyst for oxygen evolution in electrolysers. The reversibility of the redox process provides great potential for the achieved porous layers to be used as positive material in alkaline batteries.     

Laser-induced breakdown spectroscopy for semi-quantitative and quantitative analyses of artworks—application on multi-layered ceramics and copper based alloys

In the present work, we report on the analyses of different types of artworks, such as medieval glazed Umbrian pottery and copper based alloys from Roman and modern periods, performed by means of Laser Induced Breakdown Spectroscopy (LIBS). The semi-quantitative analyses on the multi-layered ceramic findings regard glaze, luster and pigment decorations present on the surface. The composition for each decorative layer was determined by estimating the contribution of the ceramic layer beneath the examined one to the whole plasma emission. Two types of ancient luster have been considered: red and gold, while the pigments examined include painted decorations of different blue tonalities. The measured elemental composition of the decorative layers resulted partially correlated with the color of the painted surface, measured by a standard UV-VIS spectrometer. In LIBS analyses of bronze samples, a procedure was developed, which improves data repeatability and extends quantitative measurements to minor elemental constituents. Results of the quantitative analyses gave indications about the manufacturing process of the artwork, its actual degree of conservation and the presence of residual surface decorations.     

X-ray emission fluorescence (XRF) analysis of origin of raw materials of light dark reddish brown porcelain and porcelain with black flower on a white background of Dangyangyu kiln

Dangyangyu kiln was an important civil porcelain production place in the North China during the Song Dynasty. In order to find out the source of raw materials of the porcelain body and glaze and their classification relationship so as to correctly distinguish them, we have used XRF to determine the major chemical elements of some porcelain samples with light brown and samples with black flower on a white background. Dynamic fuzzy cluster analysis was applied to the data. Results indicate that the origin of raw materials of light brown porcelain body samples is comparatively more concentrated, while that of the porcelain with black flower on a white background is scattered about. The origin of the body materials of those two kinds of porcelain samples is obviously different. The origin of raw materials of light brown porcelain samples is comparatively concentrated and stable, while that of the porcelain with black flower on a white background is scattered about, moreover, the origin of glaze raw materials and the formula of the two kinds are obviously different. The origin and formula of the light brown porcelain with white glaze in the interior are close to those of the white glaze of porcelain with black flower on a white background, but they are not entirely identical.     

Study of kinetics of reaction of titanium raw materials with sulphuric acid

The reaction of ilmenite titanium raw materials with sulphuric acid has been studied in a non-isothermal-non-adiabatic type calorimeter. The influence of different starting conditions, temperature and ilmenite particle-size distribution on the thermo-kinetics of the reaction was investigated. A kinetic model is presented for this heterogeneous system for a specified ilmenite particle-size distribution and starting temperature. On the basis of this model and experimentally determined parameters it it possible to analyse by simulation the autothermic reaction of digestion of different titanium ores with sulphuric acid.     

Magnetic digital microfluidics on a bioinspired surface for point‐of‐care diagnostics of infectious disease

Magnetic digital microfluidics uses magnetic force to manipulate droplets on a Teflon‐coated substrate through the added magnetic particles. To achieve a wide range of droplet manipulation, hydrophilic patterns, known as surface energy traps, are introduced onto the Teflon‐coated hydrophobic substrate. However, the Teflon‐coated substrate is difficult to modify because it is nonwettable, and existing techniques for patterning surface energy traps have many limitations. Inspired by the mussel adhesion mechanism, we use polydopamine, a bioinspired substance that adheres strongly to almost any materials, to pattern surface energy traps on the Teflon‐coated substrate with a great ease. We have optimized the polydopamine coating protocol and characterized the surface properties of the polydopamine surface energy traps. Droplet operations including particle extraction, liquid dispensing, liquid shaping, and cross‐platform transfer have been demonstrated on the polydopamine surface energy trap‐enabled magnetic digital microfluidic platform in both single‐plate and two‐plate configurations. Furthermore, the detection of hepatitis B surface antigen using ELISA has been demonstrated on the new magnetic dgitial microfluidic platform. This new bioinspired magnetic digital microfluidic platform is easy to fabricate and operate, showing a great potential for point‐of‐care applications.     

Chemical and mineralogical characterization on glazes of ceramics from Coimbra (Portugal) from the sixteenth to nineteenth centuries

Chemical, mineralogical and textural characterizations were performed on glazed pieces prepared in laboratory as well as on faiences fragments collected from the existing remains in “Santa Clara-a-Velha” monastery (Coimbra, Portugal). The chemical investigation was carried out using micro X-ray fluorescence (μ-EDXRF) and wavelength dispersive X-ray fluorescence (WDXRF); the mineralogical results using X-ray diffraction (XRD) and the textural profile was obtained by scanning electron microscopy coupled with an energy dispersive spectroscopy system (SEM-EDS). Attention has been drawn to the glaze mineralogical changes during the firing temperature process, where three different types of glazes were submitted to three different firing temperatures (800 °C, 900 °C and 1,000 °C). Under these conditions, it is possible to relate the mineralogical content of the fragments to their firing temperature. Furthermore, we focused our purposes on identifying the technological aspects of the ceramic production in Coimbra, such as the raw materials, manufacture techniques and firing temperature adopted for the glaze. The latter aspect is highly dependent on the ceramic materials. In the framework of a more general project, this survey has as premise the recognition of a pattern, which is thought to be exclusively typical from the region of Coimbra. The perspective developed in the present work is towards reliable archaeometric criteria, which can be used to characterise scientifically the ceramics from Coimbra.     

Surface‐Coated Thermally Expandable Microspheres with a Composite of Polydisperse Graphene Oxide Sheets

Surface‐modified thermally expandable microcapsules (TEMs) hold potential for applications in various fields. In this work, we discussed the possible surface coating mechanism and reported the properties of TEMs coated with polyaniline (PANI) and polydisperse graphene oxide sheets (ionic liquid‐graphene oxide hybrid nanomaterial (ILs‐GO)). The surface coating of PANI/ ILs‐GO increased the corresponding particle size and its distribution range. The morphologies analyzed by scanning electron microscopy indicated that no interfacial gap was observed between the microspheres ink and substrate layer during the substrate application. The thermal properties were determined by thermogravimetric and differential thermal analyses. The addition of ILs‐GO to the polyaniline coating significantly improved the thermal expansion and thermal conductivity of the microcapsules. The evaporation of hexane present in the core of TEMs was not prevented by the coating of PANI/ ILs‐GO. The printing application of TEMs showed excellent adaptability to various flexible substrates with great 3D appearance. By incorporating a flame retardant agent into TEMs coated by PANI/ILs‐GO, finally, these TEMs also demonstrated a great flame retardant ability. We expect that these TEM‐coated PANI/ ILs‐GO are likely to have the potential to improve the functional properties for various applications.     

Thermal conductivity of lightweight aggregate based on coal fly ash

The article presents the results of physical and chemical properties of lightweight aggregates (LWA) obtained by the thermal treatments of raw composition based on fly ash, supplied by electric plants from Serbia. The production process of LWA consists of raw material preparation, plastic shaping?Cextrusion, granulation, and thermal treatment at three temperatures: 1100, 1150, and 1200?°C. The final firing temperature (T?=?1150?°C) is chosen based on the mechanical and physical properties of the designed aggregates. The particle-size distribution of the LWAs is unimodal (d????16?mm) while the density value varies from 0.98 to 1.99?g/cm³. The water absorption values are determined by use of two methods: 24?h of soaking in cold water and 5?h of boiling. The thermal conductivity of unbound, fired LWA particles is determined by measuring the amount of axially transferred heat in the stationary state. The obtained value of the LWA thermal conductivity (???=?0.0872?W/mK, T?=?1150?°C) is suitable for the production of structural concrete blocks with improved thermal insulating properties. Because of their high-porosity and -compressive strength values, the designed LWA could be used instead of the conventional aggregates in the production of concrete blocks. Consequently, a real valorization of the waste material such as fly ash in Serbia was established.     

Characterization of the surface properties of persimmon leaves by FT-Raman spectroscopy and wicking technique

To fit the request of developing new biomaterials using persimmon leaves as raw material, this paper reported the surface free energy and related components, e.g. the Lifshitz-van der Waals and Lewis acid-base components for persimmon leaves estimated by means of the column wicking technique. Considering this natural material might be varied of its properties with growing area, a characterization of it was initially performed by applying the FT-Raman spectroscopy. Based on the determined results, persimmon leaves have greater surface free energy, gammaS, than cellulose though it has been found rich in this component, e.g. of about 68.28%. Moreover, it was further observed that the persimmon leaves have great Lewis acid-base interactions component, gammaS(AB), contributed by the Lewis acid component, gammaS+. This suggests that the persimmon leaves are available to convert to new biomaterials expected forms.     

The surface trans effect: influence of axial ligands on the surface chemical bonds of adsorbed metalloporphyrins

The chemical bond between an adsorbed, laterally coordinated metal ion and a metal surface is affected by an additional axial ligand on the metal ion. This surface analogon of the trans effect was studied in detail using monolayers of various M(II)-tetraphenylporphyrins (MTTPs, M = Fe, Co, Zn) and their nitrosyl complexes on a Ag(111) surface. X-ray photoelectron spectroscopy (XPS) shows that the oxidation state of the Fe and Co (but not Zn) ions in the MTPP monolayers is reduced because of the interaction with the substrate. This partial reduction is accompanied by the appearance of new valence states in the UV photoelectron and scanning tunneling spectra (UPS and STS), revealing the covalent character of the ion-substrate bond. Subsequent coordination of nitric oxide (NO) to the metal ions (Fe, Co) reverses these surface-induced effects, resulting in an increase of the oxidation states and the disappearance of the new valence states. Removal of the NO ligands by thermal desorption restores the original spectroscopic features, indicating that the described processes are fully reversible. The NO coordination also changes the spin state and thus the magnetic properties of the metal ions. Density-functional theory (DFT) calculations on model systems provide structural and energetic data on the adsorbed molecules and the surface chemical bond. The calculations reveal that competition effects, similar to the trans effect, play a central role and lead to a mutual interference of the two axial ligands, NO and Ag, and their bonds to the metal center. These findings have important implications for sensor technology and catalysis using supported planar metal complexes, in which the activity of the metal center is sensitively influenced by the substrate.     

Study of perovskite compounds

Perovskites belong to the great group of the inorganic pigments and thanks to their excellent properties they have been widely used in an industry. CaTiO₃, BaTiO₃ and SrTiO₃ with the perovskite structure were prepared in this work. These compounds were synthesized with using the solid state reaction by calcination in temperature region 1000–1200°C. The thermal analysis was used for characterization of thermal behaviour and formation of tested perovskites. The main aim of this work was studied the influence of calcination temperature on colour properties of perovskites. Colour properties of powdered compounds and samples applied into ceramic transparent glaze P 07491 were also studied. The tested compounds can be described by different light colour hues and that depending on calcining temperature. The structures of the powdered compounds were studied by X-ray diffraction analysis.     

Aging of a medical device surface following cold plasma treatment: Influence of low molecular weight compounds on surface recovery

The surface of medical devices is of great importance for biocompatibility. Surface properties can evolve with a material treatment, time, and storage conditions. In this work, poly(urethane) catheters sterilised by cold nitrogen plasma treatment, were subjected to air and temperature aging in order to evaluate the influence of humidity and temperature on surface recovery. The surface of catheters was analysed by contact angle measurements and XPS. Faster surface changes upon aging were observed at high temperature (45 °C) and relative humidity (90%). For the commercial poly(urethane) catheters analysed in this work, the importance of the nature and polymorphism of additives added to the polymer (lubricant, antioxidant) in the recovery process was demonstrated. Indeed, DSC and TSC showed that additive transitions (relaxation, melting…) could govern the aging process.     

Heat-induced alterations in the surface population of metal sites in bimetallic nanoparticles

The ability to alter the surface population of metal sites in bimetallic nanoparticles (NPs) is of great interest in the context of heterogeneous catalysis. Here, we report findings of surface alterations of Pt and Ru metallic sites in bimetallic carbon-supported (PtRu/C) NPs that were induced by employing a controlled thermal-treatment strategy. The thermal-treatment procedure was designed in such a way that the particle size of the initial NPs was not altered and only the surface population of Pt and Ru was changed, thus allowing us to deduce structural information independent of particle-size effects. X-ray absorption spectroscopy (XAS) was utilized to deduce the structural parameters that can provide information on atomic distribution and/or extent of alloying as well as the surface population of Pt and Ru in PtRu/C NPs. The PtRu/C catalyst sample was obtained from Johnson Matthey, and first the as-received catalyst was reduced in 2 % H2 and 98 % Ar gas mixture at 300 degrees C for 4 h (PtRu/C as-reduced). Later this sample was subjected to thermal treatment in either oxygen (PtRu/C-O2-300) or hydrogen (PtRu/C-H2-350). The XAS results reveal that when the as-reduced PtRu/C catalyst was exposed to the O2 thermal-treatment strategy, a considerable amount of Ru was moved to the catalyst surface. In contrast, the H2 thermal-treatment strategy led to a higher population of Pt on the PtRu/C surface. Characterization of the heat-treated PtRu/C samples by X-ray diffraction and transmission electron microscopy reveals that there is no significant change in the particle size of thermally treated samples when compared to the as-received PtRu/C sample. The electrochemical properties of the as-reduced and heat-treated PtRu/C catalyst samples were confirmed by cyclic voltammetry, CO-adsorption stripping voltammetry, and linear sweep voltammetry. Both XAS and electrochemical investigations concluded that the PtRu/C-H2-350 sample exhibits significant enhancement in reactivity toward methanol oxidation as a result of the increased surface population of the Pt when compared to the PtRu/C-O2-300 and PtRu/C as-reduced samples.     

Integrated investigations for the characterisation of Roman lead-glazed pottery from Pompeii and Herculaneum (Italy)

A multi-analytical approach was used to investigate Roman lead-glazed ceramic artefacts from archaeological excavations at Pompeii and Herculaneum (Italy) aiming at defining the production technology of both glaze and ceramic body, by way of integrated investigations. The chemical, structural, and micro-morphological characterisations were performed using a combination of laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS), optical microscopy (OM), scanning electron microscopy (SEM), and micro-Raman spectroscopy. Fragments of artefacts (skyphoi, oil lamps, bowls, askoi, amphorae, krateres) of great historical and archaeological interest were sampled. LA-ICP-MS was used to determine the elemental composition by virtue of its effective lateral resolution, its ability to detect most elements and also to analyse comparably small samples. All the archaeological objects were coated with a lead-based glaze produced using a lead oxide-plus-quartz mixture, with sodium/potassium feldspars added as a flux and two different metals used: copper and iron. Two types of ceramic pastes have been identified, but chemometric techniques support the hypothesis of a Campanian provenance for the raw materials. Degradation phenomena such as the partial devitrification of the glaze, i.e. the slow structural reorganisation towards stable crystalline phases, and the leaching by mineral dissolution in the soil, were determined.     

Study of thermal behaviour and stability of Co-doped malayaite ceramic pigments

This contribution deals with the preparation and characterization of Co-doped malayaite pigments. Pigment samples were prepared by solid-state reaction at different firing temperatures (1200–1400 °C). For characterization of thermal behaviour, pigment formation and thermal stability were studied by the methods of thermal analyses. The compounds were evaluated from standpoint of their phase composition and particle size distribution. The XRD analysis of samples prepared at 1,300–1,400 °C indicates the occurrence of two-phase compounds, i.e. the malayaite and the cassiterite. Average value of mean particle size of tested malayaites is moved ~10 μm. The great attention was focused on determination of impact of firing temperature on the pigment-application properties. Because the malayaite compounds belong into ceramic pigments, the pigment-application properties were observed after application into organic matrix in mass tone and middle-temperature glaze in different pigment amounts. Generally, the colour appearance of tested malayaites is dependent on the firing temperature and it moves in different shades of blue colour. From pigmentary point of view, it is possible to recommend 15 % of mass pigment for sufficient colouring of middle-temperature glaze. The higher firing temperature provides the formation of pigment samples with the higher saturation and the higher values of hue angle. For preparation of Co-doped malayaite pigments with the excellent colour properties, the firing temperature 1,350 °C is necessary.     

载体表面性质对Cu/ZrO2催化剂CO加氢反应行为的影响

用XRD、LRS、NH₃-TPD、CO₂-TPD和CO-FTIR等表征手段考察了不同温度焙烧的氧化锆表面性质的差别,特别是表面酸碱性的差异对Cu/ZrO₂催化剂CO加氢反应行为的影响。结果表明,不同温度焙烧的氧化锆表面酸碱性具有较大的差异,其中以450℃焙烧的氧化锆具有较高的表面碱性和最低酸性。这些表面性质的差异对于Cu/ZrO₂催化剂的CO吸附行为产生较大的影响,进而影响CO的加氢反应活性。以450℃焙烧的氧化锆为载体时,Cu/ZrO₂催化剂具有较好的反应活性。     

Influence of the particle-size reduction by ultrasound treatment on the dehydroxylation process of kaolinites

Kaolinites from well-known sources (KGa-1 and KGa-2) were used to study the influence of the particle-size reduction on the dehydroxylation process. Size reduction of particles was obtained by ultrasound treatment to avoid the effect of the progressive amorphization of the structure, which takes place with the traditional grinding treatment.The particle-size reduction causes an increase of the mass loss between 140 and 390°C attributed to the loss of the hydroxyl groups exposed on the external surface of kaolinite; a shift to lower temperatures of the endothermic effect related with the mass loss between 390 and 600°C and a shift of the end of dehydroxylation to lower temperatures. The first modification can be explained by an increase of the number of hydroxyls exposed on the external surface of kaolinite which is proportional to the new surface generated in the particle reduction process, whereas the shift of the dehydroxylation to lower temperatures is related to the reduction of the dimensions of the particles which favour the diffusion controlled mechanisms.Comparing between the DTA curves to the TG curves of the studied samples shows that the observed modifications in the thermal properties induced by the particle-size reduction are greater for the low-defect kaolinite. The intensity of these modifications depends on the effectiveness of the ultrasound treatment.The authors are grateful to S. Yariv, I. Lapides and S. Shoval for carefully reviewing this paper and making helpful comments. This research has been supported by Research Project MAT 2002-03774 from the Spanish Ministry of Science and Technology and Research Groups FQM-187 and RNM-0199 of the Junta de Andalucia.     

Patterning the surface cytophobicity of an albumin-physisorbed substrate by electrochemical means

Spatiotemporal control of surface properties under physiological conditions such as those found in culture media is an important technique in fundamental cell biology, tissue engineering, and cell-based bioelectronics. To this end, we have developed a mild, wet cellular micropatterning technique. The principle of the technique is based on the fact that the cell-repellant property of the albumin-coated substrate rapidly switches to cell-adhesive upon exposure to the reactive oxidizing agent, electrochemically generated hypobromous acid. Herein, we report the effect of the hypobromous acid on serum albumin physisorbed on a hydrophobic substrate. It was found that albumin molecules detach from the substrate by application of the oxidizing agent, resulting in exposure of the underlying hydrophobic surface to the liquid phase. The adsorption of extracellular matrix proteins such as fibronectin onto the hydrophobic surface induces cell adhesion and growth.