The in vitro toxicology of Swedish snus

Three commercial brands of Swedish snus (SWS), an experimental SWS, and the 2S3 reference moist snuff were each tested in four in vitro toxicology assays. These assays were: Salmonella reverse mutation, mouse lymphoma, in vitro micronucleus, and cytotoxicity. Water extractions of each of the 5 products were tested using several different concentrations; the experimental SWS was also extracted using dimethyl sulfoxide (DMSO). Extraction procedures were verified by nicotine determinations. Results for SWS in the mutagenicity assays were broadly negative: there were occasional positive responses, but these were effectively at the highest concentration only (concentrations well above those suggested by regulatory guidelines), and were often associated with cytotoxicity. The 2S3 reference was unequivocally positive in one of the three conditions of the micronucleus assay (MNA), at the highest concentration only. Positive controls produced the expected responses in each assay. The SWS data are contrasted with data reported for combusted tobacco in the form of cigarettes, where strongly positive responses have been routinely reported for mutagenicity and cytotoxicity. These negative findings in a laboratory setting concur with the large amount of epidemiological data from Sweden, data showing that SWS are associated with considerably lower carcinogenic potential when compared with cigarettes

Potential applications of nanotechnology in thermochemical conversion of microalgal biomass

The rapid decrease in fossil reserves has significantly increased the demand of renewable and sustainable energy fuel resources. Fluctuating fuel prices and significant greenhouse gas (GHG) emission levels have been key impediments associated with the production and utilization of nonrenewable fossil fuels. This has resulted in escalating interests to develop new and improve inexpensive carbon neutral energy technologies to meet future demands. Various process options to produce a variety of biofuels including biodiesel, bioethanol, biohydrogen, bio-oil, and biogas have been explored as an alternative to fossil fuels. The renewable, biodegradable, and nontoxic nature of biofuels make them appealing as alternative fuels. Biofuels can be produced from various renewable resources. Among these renewable resources, algae appear to be promising in delivering sustainable energy options. Algae have a high carbon dioxide (CO2) capturing efficiency, rapid growth rate, high biomass productivity, and the ability to grow in non-potable water. For algal biomass, the two main conversion pathways used to produce biofuel include biochemical and thermochemical conversions. Algal biofuel production is, however, challenged with process scalability for high conversion rates and high energy demands for biomass harvesting. This affects the viable achievement of industrial-scale bioprocess conversion under optimum economy. Although algal biofuels have the potential to provide a sustainable fuel for future, active research aimed at improving upstream and downstream technologies is critical. New technologies and improved systems focused on photobioreactor design, cultivation optimization, culture dewatering, and biofuel production are required to minimize the drawbacks associated with existing methods. Nanotechnology has the potential to address some of the upstream and downstream challenges associated with the development of algal biofuels. It can be applied to improve system design, cultivation, dewatering, biomass characterization, and biofuel conversion. This chapter discusses thermochemical conversion of microalgal biomass with recent advances in the application of nanotechnology to enhance the development of biofuels from algae. Nanotechnology has proven to improve the performance of existing technologies used in thermochemical treatment and conversion of biomass. The different bioprocess aspects, such as reactor design and operation, analytical techniques, and experimental validation of kinetic studies, to provide insights into the application of nanotechnology for enhanced algal biofuel production are addressed

Effect of the silane concentration on the selected properties of an experimental microfilled composite resin

The aim of present study was evaluate the effect of different percentages of an organo-functionalized silane monomer as adhesion promoter between barium borosilicate glass fillers and (co)monomer blend in experimental dental composite resin. Gamma-methacryloxypropyltrimethoxysilane (γ-MPS) was assessed in an experimental luting cement, at the concentrations of 0, 1, 3, 5, 7 and 10 (wt%). The experimental resin without fillers was used as control group. The flexural strength (FS) and elastic modulus (E) were obtained by mini-flexural test and expressed in MPa and GPa, respectively. Water sorption (WS) and solubility (SL) were determined based on ISO standard 4049:2000. Kruskal–Wallis and Student–Newman–Keuls test were used for comparisons of FS, E and WS. The comparisons of SL means were performed using one-way ANOVA and Tukey's method (α = 5 %). The treatment with 3 % silane revealed statistically higher FS, while the group treated with 1 % silane showed statistically higher E than 3 % silane (p < 0.05) and E similar to control. The experimental composite without filler content showed the highest SL (p < 0.05) while the control composite showed the highest WS (p < 0.05). Based on present findings, flexural strength and elastic modulus can sometimes be improved with lower concentrations (1–3 %) rather than higher concentrations (5–7 %) of the silane (γ-MPS) used as coupling agent on barium borosilicate glass filler microparticles of the dental composite resin