Much research has been done on bone cells, but only a few studies deal with biomaterial-induced effects on human osteoclasts, which may take on an important role in the successful regeneration of bone. In order to highlight such effects, human peripheral blood mononuclear cells (PBMCs) were extracted from venous blood, differentiated to osteoclasts and then cultured in, the presence of five particulate hydroxyapatite (HA)/β-tricalcium phosphate (TCP) biomaterials, on bovine bone slices and glass cover slips. The biomaterials, AlgOSS 50/50 (50 % HA/50 % TCP), AlgOSS 20/80 (20 % HA/80 % TCP), Algipore (98 % HA), Cerasorb (100 % TCP) and Bio-Oss (100 % HA) were chosen to assess their influence on cell morphology and numbers. Light microscopic evaluation was performed during ongoing cell culture. After 21 d of cultivation, the biomaterial-induced effects on osteoclastic resorption of the bone slices were evaluated by scanning electron microscopy (SEM). Osteoclast-like cells were identified by TRAP staining. All five biomaterials showed larger area fractions of resorbed bone than the control (5.6 ± 6.8 %), as measured on SEM images. The purely hydroxyapatite-based Algipore (9.8 ± 9.7 %) and Bio-Oss (7.9 ± 8.8 %) showed significantly elevated area fraction rates (p ≤ 0.05) of bone resorption. Light microscope evaluation revealed a significant, but inhibiting effect of Cerasorb (p = 0.05). These data indicated that introducing of small biomaterial hydroxyapatite particles may have improved the performance of bone substitute materials.

Powders of hexagonal (W,Ta)C were produced following a two-step carburization process with (W,Ta)2C powder as an intermediate product. XRD measurements indicate that higher temperatures during the first carburization step increase the fraction of Ta in the (W,Ta)2C structure where lower temperatures during the second carburization step seems to increase the fraction of Ta in the (W,Ta)C structure. Lower temperatures during the carburization steps increase the fraction of Σ2 WC/WC grain boundaries and cause the formation of what is interpreted as Σ4 boundaries. The (W,Ta)C powders can be successfully used to produce fine grained WC-Co based cemented carbides. The pre-alloying with Ta appears to have a softening effect on the material.

WC powder with increased Ta doping has been produced. Tungsten and tantalum metal powders were cocarburized to yield a mixture of cubic and hexagonal carbide. The carburization was made through a two-step carburization process with (W,Ta)(2)C powder as an intermediate product. X-ray diffraction analysis showed that the lattice parameters of the hexagonal phase in the fully carburized powder were larger than those of pure WC indicating the formation of a mixed crystal carbide, (W,Ta)C. The powder with the largest lattice parameters was investigated in detail. A method to produce atom probe tomography specimens of this powder was developed. The largest Ta solubility, expressed as Ta/(Ta + W), was 0.086 which is more than four times higher than what previously has been observed. In addition, it was found with electron backscatter diffraction that the (W,Ta)C grains had a large fraction of Sigma 2 grain boundaries as well as a small fraction of what was suggested as Sigma 4 grain boundaries. (C) 2015 Elsevier Ltd. All rights reserved.

Based on our earlier work on the formation of a hexagonal (W,Cr)C mixed crystal carbide, the formation of (W,Me)C (Me=Ti, Ta, V, V+Cr) solid solutions was studied in the temperature range of 1450°C to 1950°C. A two step carburization procedure was used for their preparation: In a first step, (W,Me)2C was formed, which in a second carburization step was then transformed into the (W,Me)C carbide.

In micro-/nanomachined devices and systems, aluminum nitride (AlN) thin films are widely used due to their piezoelectric properties. This work evaluates the potential of modifying the interface between the AlN thin film and the silicon (Si) wafer serving as bottom electrode for optimized crystallographic orientation and, hence, improved electrical and piezoelectric properties. The films were analyzed using temperature-dependant leakage current measurements, transmission electron microscopy, and x-ray diffraction. By preconditioning of the Si substrate surface applying sputter etching prior to film deposition, leakage current levels are substantially decreased and an increased (002) orientation of the AlN grains is observed.

Zinc metal nanowires have been oxidized at temperatures of 200–500 °C in ambient air in order to obtain ZnO nanowires. X-ray diffraction investigations reveal a complete transformation from Zn to ZnO at a temperature of ≥300 °C within 30 min. Temperature-induced grain growth attains saturation at about 350 °C. Scanning electron microscopy studies show a pronounced morphology change from smooth, unidirectional to rough, bursted nanorods at a temperature of >250 °C. The corresponding transformation mechanism is discussed.

The research on bioceramics during the last decades has proved that the bioactivity of inorganic bone grafts depends fundamentally on an optimal combination of chemistry and structural porosity. This study presents a comparison of a resorbable monophasic hydroxyapatite (HA) and several newly developed resorbable biphasic hydroxyapatite – ß‐tricalcium phosphate (HA/TCP) composites both derived from naturally grown red marine algae with respect to the phase composition, microstructure and porosity. The highly porous three dimensional mineral scaffold of the native alga is maintained in the final products all investigated materials and possesses a pronounced interconnecting microporous structure. There are generally high values of specific porosity calculated for all tested materials: 1.07 cm3/g for pure phycogenic HA and between 0.65 cm3/g and 1.04 cm3/g for phycogenic biphasic HA/TCP composites with various HA/TCP ratios. The ultrastructure of the phycogenic HA/TCP composites changes significantly with the building and the increase of the ß‐TCP phase due to the bigger polyedric ß‐TCP crystals compared to the finer polycrystalline HA. Despite these structural changes the interconnected porous scaffold is kept throughout the production process. In all investigated materials the porosity is mainly based on pores with pore sizes between 1 and 10 μm in diameter, which is given by the structure of the natural alga. The specific chemistry combined with the structural porosity is decisive for the high in‐vivo bioactivity of the studied materials.

The influence of the Pt and sulfate concentration on the activity of Pt containing sulfated zirconia for n -heptane conversion was investigated. Pt was deposited on the support by impregnation and by photocatalytic deposition. The amount deposited was 2.5 and 0.4 wt% respectively. For comparison a hybrid catalyst consisting of sulfated zirconia and Pt on SiO 2 was prepared. As supports a commercial sulfated zirconia with a fixed sulfate concentration, a commercial and self synthesized Zr(OH) 4 were used. The sulfate content varied between 20 and 60% of a monolayer. The shifts to higher frequency in the IR spectra of CO adsorbed on Pt correlate with the increasing amounts of sulfates on zirconia and are attributable to the changes in the electron density of the supported metal, i.e. the electron deficiency of Pt increases with increasing concentration of acid sites. After activation in air and reduction in hydrogen two SO 2 peaks were detected by a temperature programmed heating procedure (TPE—temperature programmed evolution). The lower the desorption temperature of the first SO 2 peak, the higher the activity. The shift to lower temperature is connected with a higher Pt and sulfate concentration, furthermore with the proximity of the metal to acid sites. The catalysts with a low sulfate concentration possess only Lewis acid sites and are inactive for n -heptane conversion. At higher sulfate concentration, Brønsted acid sites are present and the catalysts are active. The concentration of these acid sites is related to the concentration of sulfates, which desorb at lower temperature.

Active, inactive, coked and resulfated SZ and Pt/SZ samples were investigated by XRD, TG, TPE, TPD and IR measurements. As test reaction conversion of n-heptane at 200 degrees C and atmospheric pressure was chosen. The active catalysts exhibit the pure tetragonal phase, have a sulfate content corresponding to a surface coverage of more than half a monolayer and show Bronsted acidity. It is assumed that the active species consist of pyrosulfate groups, which can oxidize hydrogen (alkanes) to water (and alkenes) by decomposing into sulfate groups and adsorbed SO2.The atmosphere of the first activation step of Pt/SZ does not seem to have any influence on the performance of Pt/SZ. For regeneration an oxidative atmosphere, a temperature of 500 degrees C and reduction in hydrogen at 200 degrees C is necessary to restore the catalytic activity of Pt/SZ completely. If, however, regeneration of PUSZ is done in He or N-2, a remarkable loss of SO, was observed and the catalyst became irreversibly inactive. The sulfur species, which are more weakly bonded to the surface after a reductive step are evolved at lower temperatures (between 300 and 600 degrees C) in an inert gas atmosphere. This species are essential for catalytic activity, whereas the sulfate groups, which are removed at temperatures higher than 600 degrees C, are inactive for n-alkane conversion.The inactive SZ and PUSZ samples exhibit the tetragonal and monoclinic structure, have lost approximately 40% of their sulfate groups and possessed only Lewis acid sites. If an inactive Pt/SZ sample was resulfated Bronsted acidity was regenerated and the sample was active, however to a lesser extent than a fresh catalyst.The changes occurring during coking did not affect the textural properties; no changes of the crystal structure were detected by XRD. Almost all coking was observed in the first minutes of reaction. Regeneration in air reestablished the activity whereas regeneration in an inert atmosphere led to a loss of sulfate groups and therefore to inactivity. (c) 2005 Elsevier B.V. All rights reserved.

K3.6Na8.4[Ge2O7]2, M(r) = 848.22, monoclinic, P2(1)/c, a = 5.939 (1), b = 15.062 (3), c = 19.904 (3) angstrom, beta = 93.31 (1)-degrees, V = 1777.5 (5) angstrom 3, Z = 4, D(x) = 3.170 g cm-3, lambda(Mo K-alpha) = 0.71069 angstrom, mu = 77 cm-1, F(000) = 1604, T = 298 K, R = 0.033, wR = 0.038 for 3184 independent reflections. The structure is made up of ditetrahedral Ge2O7 groups linked by Na and K atoms. Two of the twelve alkali metal sites were found to have mixed Na/K occupancies.

AbstractThe title compound (III), synthesized by reaction of K2GeO3 and KOH under the conditions indicated in the scheme, crystallizes in the monoclinic system (Pc, Z=2).

AbstractA reevaluation of already known data con‐ firms the isotypism of the two crystal structures.

The crystal structure of K 2Ge0 3 has been determined by single crystal X-ray diffraction. The compound crystallizes in the orthorhombic space group Pbca with a = 23,033(5), b = 32,887(8), c = 5,453(1) Ä and Z=40. Least-squares refinement of the structure using 2600 data with 3σ(/) gave R = 0.090. The crystal contains infinite single chains with two [Ge04] tetrahedra in the repeat unit. The symmetry relation between the substructure of K2Ge03 (cell dimensions a/2, b/5, c ; symmetry Cmcm) and the structure of Na2Ge03 is discussed.

The crystal structure of N a K G e 0 3 has been determined from single crystal X-ray data and refined to R = 0.048. The unit cell is orthorhombic, space group Pbnlt (No. 33), a = 10.675(5), 6=6.895(3), c=4.803(l ) A and Ζ = 4 . The crystal contains infinite zweier single chains of composition [Ge03]n ~ that are parallel to the c axis. The projection of the chains on (001) reveals pseudohexagonal symmetry, very much like N a 2 G e 0 3 where this symmetry results from the approximately close-packed arrangement of the oxygen atoms. In N a K G e 0 3 , however, close-packing is restricted to ribbonlike portions of the structure.