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.     

Oxidative Coupling of Poly (2-Vinylthiophene) Chains by FeCl3

Summary Poly(2-vinylthiophene) (PVT) can be cross linked with FeCl₃ either in dichloromethane solution or when immobilized on silica particles. Extend of cross linking is strongly dependent on the FeCI₃/PVT ratio used for the reaction as shown by GPC plots and gravimetric analyses of the formed insoluble polymer fraction. A stoichiometric FeCl₃/PVT ratio of about four is necessary to achieve complete conversion, because consecutive formations of thiophene H⁺FeCl₄ ^- and bisthiophene H⁺FeCl₄ ^- sigma complexes take place. PVT can be also cross linked when adsorbed on silica using the same procedure. The cross-linking is proved by IR and ¹³C CPiMAS NMR spectroscopy.     

(R)-acetoin-female sex pheromone of the summer chafer Amphimallon solstitiale (L.)

Extracts of Amphimallon solstitiale (L.), a well known, widely distributed and rather common European scarab beetle, were analyzed by GC-MS and GC-EAD. Acetoin -(R):(S) < 9:1 - as well as 2,3-butanediol -(2R,3R):(2S,3S) :meso = 1:1:9 - were present in extracts of both males and females. Although (2S,3S)-butanediol did not show any EAD activity, the other compounds elicited strong responses exclusively with male antennae. In contrast, several EAD active green leaf volatiles were detected equally well by male and female antennae. During preliminary field bioassays, (R)-acetoin was highly attractive to swarming males, whereas neither rac-acetoin nor the 2,3-butanediols showed activity. Therefore, (R)-acetoin is the female sex pheromone of A. solstitiale.     

Butyltin(IV) Benzoates: Inhibition of Thioredoxin Reductase,Tumor Cell Growth Inhibition,and Interactions with Proteins

Thioredoxin reductase (TrxR) is overexpressed in cancer cells and is therefore a putative cancer target. Inhibition of this enzyme is considered an important strategy for the development of new chemotherapeutic agents with a specific mechanism of action. Organotin compounds have been described as experimental antitumor agents, yet their mechanism of action remains largely unknown. Based on the outcome of a virtual screening study, various di‐ and tri‐n‐butyltin(IV) carboxylates were synthesized, and their biological properties were evaluated. All synthesized compounds were able to inhibit TrxR selectively within the micromolar range and showed potent antitumor activity against HT‐29 and MCF‐7 cancer cell lines. Moreover, tin(IV) organometallics were found to strongly induce apoptosis in the BJAB lymphoma cell line. Mass spectrometry and atomic absorption spectroscopy experiments revealed metal binding to proteins, and efficient cellular uptake was observed using a di‐n‐butyltin(IV) complex as an example.     

Spectroscopic and Theoretical Study on Electronically Modified Chromophores in LOV Domains: 8‐Bromo‐ and 8‐Trifluoromethyl‐Substituted Flavins

Two chemically synthesized flavin derivatives, 8‐trifluoromethyl‐ and 8‐bromoriboflavin (8‐CF₃RF and 8‐BrRF), were photochemically characterized in H₂O and studied spectroscopically after incorporation into the LOV domain of the blue light photoreceptor YtvA from Bacillus subtilis. The spectroscopic studies were paralleled by high‐level quantum chemical calculations. In solution, 8‐BrRF showed a remarkably high triplet quantum yield (0.97, parent compound riboflavin, RF: 0.6) and a small fluorescence quantum yield (0.07, RF: 0.27). For 8‐CF₃RF, the triplet yield was 0.12, and the fluorescence quantum yield was 0.7. The high triplet yield of 8‐BrRF is due to the bromine heavy atom effect causing a stronger spin–orbit coupling. Theoretical calculations reveal that the decreased triplet yield of 8‐CF₃RF is due to a smaller charge transfer and a less favorable energetic position of T₂, required for intersystem crossing from S₁ to T₁, as an effect of the electron‐withdrawing CF₃ group. The reconstitution of the LOV domain with the new flavins resulted in the typical LOV photochemistry, consisting of triplet state formation and covalent binding of the chromophore, followed by a thermal recovery of the parent state, albeit with different kinetics and photophysical properties.     

Minimizing Concentration Effects in Water-Based,Laminar-Flow Condensation Particle Counters

Concentration effects in water condensation systems, such as used in the water-based condensation particle counter, are explored through numeric modeling and direct measurements. Modeling shows that the condensation heat release and vapor depletion associated with particle activation and growth lowers the peak supersaturation. At higher number concentrations, the diameter of the droplets formed is smaller, and the threshold particle size for activation is higher. This occurs in both cylindrical and parallel plate geometries. For water-based systems, we find that condensational heat release is more important than vapor depletion. We also find that concentration effects can be minimized through use of smaller tube diameters, or more closely spaced parallel plates. Experimental measurements of droplet diameter confirm modeling results.

© 2013 American Association for Aerosol Research     

Comparison of Sampling Methods for Carbonaceous Aerosols in Ambient Air

Measurement methods for fine particle carbon were compared under field sampling conditions. Sampling methods included filtration, impaction, and adsorption-corrected filtration. Systems were operated side-by-side for nine consecutive days in the Los Angeles Basin. Analytical methods were compared separately. For organic carbon and total carbon, ambient measurements showed greater variability than could be accounted for by differences in analytical methods, and these differences are attributed to sampling methodology. The highest reported concentrations were obtained by quartz filter sampling; the lowest were from the sum of the impactor stages (excluding the quartz afterfilters). Positive artifact from the adsorption of gaseous vapors on quartz fiber filters was significant. However, correction for vapor adsorption by subtraction of the carbon value on the second of two filters in series did not completely eliminate the dependence of the apparent total aerosol carbon concentration on filter face velocity or sample duration     

A Method for Particle Size Amplification by Water Condensation in a Laminar,Thermally Diffusive Flow

A new method is presented for the enlargement of particle size through condensation of water vapor in a laminar, thermally diffusive flow. The method involves the introduction of an air flow at temperature T _i into a wet-walled tube at a temperature T_w > T_i . This approach yields higher supersaturation values than either mixing or cold-walled condensers when operating between the same temperature extremes. Model results for the saturation profiles within the condensing region show that the peak supersaturations are reached along the centerline of the flow, and that the activation efficiency curves are steeper for large temperature differences when the cutpoint diameter is smaller. Experiments conducted with three types of aerosol, oleic acid (a water-insoluble oil), a mixture of oxalic acid and sulfate, and with ambient laboratory aerosol confirmed that condensational growth is achieved with this approach, although experimental cutpoints are somewhat higher than predicted for wettable particles.     

Comparison of Particle Size Distributions at Urban and Agricultural Sites in California's San Joaquin Valley

As part of the California Regional PM _2.5 and PM ₁₀ Air Quality Study (CRPAQS) particle size distributions were measured simultaneously at two sites; the city of Fresno and the agricultural site of Angiola. Reported here are data obtained by scanning mobility analysis over the size range from 10 nm to 400 nm for the intensive study period from December 1, 2000 through February 6, 2001. These high time resolution data show variability in the character of the distributions, as well as the in the total number concentrations. The most pronounced feature of the data set is a consistent, nighttime maxima in particle number concentrations with a modal diameter near 80 nm during the evening hours at the urban Fresno site. Although these maxima are correlated with CO, NO, and black carbon, the particle size is larger than the 30–40 nm modal diameters observed for traffic aerosols during the commute hours, and is attributed to a non-vehicle source. At the agricultural site, the morning maxima particle number concentration coincides with the maxima in NO concentration, but often precedes the morning maxima in black carbon. Values for the geometric mean particle diameter varied from day to day, but are correlated between the two sites, with somewhat larger particle sizes at Angiola during periods of stagnation.     

Using Regional Data and Building Leakage to Assess Indoor Concentrations of Particles of Outdoor Origin

Time-resolved fine particle concentrations of nitrate, sulfate, and black carbon were examined to assess the appropriateness of using regional data and calculated air exchange rates to model indoor concentrations of particles from outdoor sources. The data set includes simultaneous, sub-hourly aerosol composition measurements at three locations: a regional monitoring site in Fresno, California, inside of an unoccupied residence in Clovis, California, located 6 km northeast of the regional site, and immediately outside of this same residence. Indoor concentrations of PM_2.5 nitrate, sulfate, and black carbon were modeled using varying sets of inputs to determine the influence of three factors on model accuracy: the constraints of the simplified indoor-outdoor model, measured versus modeled air exchange rates, and local versus regional outdoor measurements.

Modeled indoor concentrations captured the lag and attenuation in indoor concentrations as well as the differences among chemical constituents in the indoor-outdoor concentration relationships. During periods when the house was closed and unoccupied, use of air exchange rates calculated from the LBNL infiltration model in place of those directly measured did not contribute significantly to the error in the estimated indoor concentrations. Differences between ambient concentrations at the regional monitoring site and the immediate neighborhood contributed to estimation errors for sulfate and black carbon. Evaporation was the dominant factor affecting indoor nitrate concentrations. Even when limiting the model inputs to concentrations and meteorological parameters measured at the regional monitoring station, the modeled concentrations were more highly correlated with measured indoor concentrations than were the regional measurements themselves.