Biocompatibility of Lithium Disilicate and Zirconium Oxide Ceramics with Different Surface Topographies for Dental Implant Abutments

Gingivafibroblasts were cultured on lithium disilicate, on zirconia dioxide, and on titanium with two different surface roughnesses (0.2 µm and 0.07 µm); Proliferation (MTT), Living/Dead staining, cytotoxicity (LDH), proliferation (FGF2), and inflammation (TNFα) were analyzed after 1 day and 21 days. Furthermore, alteration in cell morphology (SEM) was analyzed. The statistical analysis was performed by a Kruskal–Wallis test. The level of significance was set at p < 0.05. There were no distinct differences in cellular behavior between the tested roughness. There were slight differences between tested materials. Cells grown on zirconia dioxide showed higher cytotoxic effects. Cells grown on lithium disilicate showed less expression of TNFα compared to those grown on zirconia dioxide or titanium. These effects persisted only during the first time span. The results indicate that the two tested high-strength ceramics and surface properties are biologically suitable for transmucosal implant components. The findings may help clinicians to choose the most appropriate biomaterial as well as the most appropriate surface treatment to use in accordance with specific clinical dental applications.     

Inelastic Neutron Scattering of Hydrogen and Butyronitrile Adsorbed on Raney-Co Catalysts

Inelastic Neutron Scattering (INS) spectroscopy was used to characterize the catalytic hydrogenation of butyronitrile on the surface of parent and LiOH-modified Raney-Co. At low pressure hydrogen is mainly adsorbed on 3-fold sites. Co-adsorbed butyronitrile and hydrogen react on the unmodified Raney-Co sample to several partially hydrogenated products that contain N-H bonds. The nature of the species suggests that bi-molecular condensation leading to N-Butylidene-1-butanamine is feasible.     

Impact of breakfast on daily energy intake - an analysis of absolute versus relative breakfast calories

Objective  

The role of breakfast energy in total daily energy intake is a matter of debate. Acute feeding experiments demonstrated that high breakfast energy leads to greater overall intake supported by cross-sectional data of a free-living population. On the other hand, a large intraindividual analysis has indicated that a high proportion of breakfast to overall intake is associated with lower daily energy intake. To evaluate these apparently contradictory results in greater detail both ways of analysis were applied to the same data set of dietary records.     

A Highly Active and Selective Manganese Oxide Promoted Cobalt-on-Silica Fischer�CTropsch Catalyst

A highly active and selective manganese oxide-promoted silica-supported cobalt catalyst for the Fischer?CTropsch reaction is reported. Co/MnO/SiO₂ catalysts were prepared via impregnation of a cobalt nitrate and manganese nitrate precursor, followed by drying and calcination in an NO/He flow. The catalysts were studied with STEM?CEELS, infrared spectroscopy measurements of adsorbed CO and Steady-State Isotopic Transient Kinetic Analysis experiments. Based on those experiments, a relation between C₅₊-selectivity and surface-coverages of CH _x -intermediates on cobalt was found.     

Activity-based profiling of retaining β-glucosidases: a comparative study

Activity-based protein profiling (ABPP) is a versatile strategy to report on enzyme activity in vitro, in situ, and in vivo. The development and use of ABPP tools and techniques has met with considerable success in monitoring physiological processes involving esterases and proteases. Activity-based profiling of glycosidases, on the other hand, has proven more difficult, and to date no broad-spectrum glycosidase activity-based probes (ABPs) have been reported. In a comparative study, we investigated both 2-deoxy-2-fluoroglycosides and cyclitol epoxides for their utility as a starting point towards retaining β-glucosidase ABP. We also investigated the merits of direct labeling and two-step bio-orthogonal labeling in reporting on glucosidase activity under various conditions. Our results demonstrate that 1) in general cyclitol epoxides are the superior glucosidase ABPs, 2) that direct labeling is the more efficient approach but it hinges on the ability of the glucosidase to be accommodated in the active site of the reporter (BODIPY) entity, and 3) that two-step bio-orthogonal labeling can be achieved on isolated enzymes but translating this protocol to cell extracts requires more investigation.     

Isotopic composition of soil,vegetation or cattle hair no suitable indicator of nitrogen balances in permanent pasture

Stable isotope signatures of cattle tail switch hair or meadow vegetation have been found to be related to nitrogen (N) surpluses of whole farms and of meadows, respectively. Permanent pastures are more patchy in terms of nutrient inputs and outputs and N balances for the whole plot do not necessarily give correct impressions of losses. We here investigated correlations between isotopic signatures and N balances calculated for different spatial and temporal scales in permanent pastures. N concentrations and δ¹⁵N values of cattle tail switch hair, vegetation and soil samples were measured in an experiment with different grazing intensities started in 2002. Results were compared to soil surface balances calculated for the whole plot or for plot areas affected by either dung, urine, grazing without excreta input, or the pasture area without dung pats. There were no significant correlations between plant or cattle hair isotopic signatures and any of the balances. N fixation probably influenced vegetation signatures, making the isotopic values less dependent on soil and more on atmospheric N. The cattle preferred short mixed vegetation with more legume biomass, which also influenced the ¹⁵N values of their hair. The ¹⁵N signatures of soil samples were the best indicators of partial N balances in these heterogeneous pastures, probably because soil values are most directly influenced by N inputs and outputs. Still, soil signatures only explained between 15 and 35% of the variation in balance results. Thus, none of the tested parameters can be used as a reliable indicator of N balance results in this heterogeneous system with small differences in budgets among treatments and potentially small plot-scale N losses.     

Polydisperse granular flows in a bladed mixer: Experiments and simulations of cohesionless spheres

The flow and segregation of polydisperse, spherical particle mixtures in a bladed mixer was investigated using experimental and computational techniques. Discrete element simulations were able to reproduce the qualitative segregation profiles and surface velocities observed experimentally. For a binary system with a 2:1 size ratio, segregation by size occurs due to a sieving mechanism. Segregation in the binary system is fast, with a fully segregated system observed after just 5 revolutions. However, the numerical simulations showed that the extent of segregation in the bladed mixer can be reduced by introducing intermediate particle sizes in between the smallest and the largest particles. Addition of intermediate particle sizes increases convective and diffusive particle motion promoting a mixing mechanism that reduces segregation via the sieving mechanism. Void fraction within the bladed mixer increases as the degree of polydispersity is increased allowing the particles to move more freely throughout the particle bed. Higher void fractions also increase the ability of large particles to penetrate deeper into the particle bed. Normal and shear stresses are also affected by particle size distributions, with lower average values obtained for the system with the largest number of particle species. Differences in the amount of stress generated by each particle species were observed. However, the difference in stresses is reduced as the number of particle species in the system is increased.     

Dynamics of diffusion with reversible binding in microscopically heterogeneous membranes: General theory and applications to dermal penetration

Essentially all biological membranes and tissues exhibit microscopic heterogeneity in the form of cellular, lamellar or other organization, and molecular diffusion in these materials is frequently slowed by binding to elements of the microstructure (“trapping”). This paper addresses situations where binding is describable as a linear reversible process at the microscale, with forward (“on”) and reverse (“off”) rate constants k_f(x) and k_r(x) that vary with position. Very commonly it is tacitly assumed that the macroscopically observable binding behavior should follow the same rate law with the substitution of appropriate effective (tissue-average) rate constants and . This assumption is probed theoretically for spatially periodic microstructures using a judicious application of numerical calculations and asymptotic analysis to prototypical one-dimensional transport problems. We find that smooth microscopic variations produce an anomalous macroscopic exchange between free and bound solute populations that is not well described by a single pair of forward and reverse rate constants, i.e., violates the usual paradigm. In contrast, discontinuous variations (as in two-phase composite media) are evidently well described by the usual paradigm. For the latter case we derive simple and general algebraic equations giving and , and generalize them to any three-dimensional unit cell representing the tissue microstructure. Validity of the formulas is demonstrated with reference to a concrete example describing molecular diffusion through the stratum corneum (barrier) layer of skin, comprising lipid (intercellular) and corneocyte (cellular) phases. Our analysis extends coarse-graining (homogenization, effective transport) theory for irreversible trapping systems to the reversible case.