Mitosis is thought to be triggered by the activation of Cdk-cyclin complexes. Here we have used RNA interference (RNAi) to assess the roles of three mitotic cyclins, cyclins A2, B1, and B2, in the regulation of centrosome separation and nuclear-envelope breakdown (NEB) in HeLa cells. We found that the timing of NEB was affected very little by knocking down cyclins B1 and B2 alone or in combination. However, knocking down cyclin A2 markedly delayed NEB, and knocking down both cyclins A2 and B1 delayed NEB further. The timing of cyclin B1-Cdk1 activation was normal in cyclin A2 knockdown cells, and there was no delay in centrosome separation, an event apparently controlled by the activation of cytoplasmic cyclin B1-Cdk1. However, nuclear accumulation of cyclin B1-Cdk1 was markedly delayed in cyclin A2 knockdown cells. Finally, a constitutively nuclear cyclin B1, but not wild-type cyclin B1, restored normal NEB timing in cyclin A2 knockdown cells. These findings show that cyclin A2 is required for timely NEB, whereas cyclins B1 and B2 are not. Nevertheless cyclin B1 translocates to the nucleus just prior to NEB in a cyclin A2-dependent fashion and is capable of supporting NEB if rendered constitutively nuclear.

This paper describes an economic analysis of the GoBiGas plant, which is a first‐of‐its‐kind industrial installation for advanced biofuel production (ABP) via gasification, in which woody biomass is converted to biomethane. A previous technical evaluation of the demonstration unit confirmed that it is technically feasible to construct advanced biofuel production plants, using commercially available and widely used components. Thus, significant cost reductions for equipment cannot be expected as a consequence of learning effects. However, the equipment itself accounted for <20% of the total investment cost at GoBiGas and there exists the potential to reduce the production cost through learning how to assemble the process and reduce project‐specific costs. The analysis shows that a plant with capacity of 200 MW of biomethane is an attractive scale for future stand‐alone ABP plants with respect to limiting the production cost. For a 200‐MW ABP plant operated using forest residues as fuel, the production cost for biomethane is estimated at approximately 600 SEK/MWh, (60€/MWh, 75US$/MWh), which is equivalent to 5.4 SEK/liter gasoline [0.54 €/liter, or 2.5USD per gallon (9.9 SEK/€, 8 SEK/USD)], where the feedstock accounts for about 36% of the production cost. The most significant uncertainty factors pertaining to the estimated production costs are expected to relate to: trade conditions; the location of the installation; and the local price of feedstock. Thus, there is some potential for implementing cost‐competitive ABP systems of smaller capacity if low‐grade feedstocks (eg, waste‐derived woody biomass) can be utilized, and/or if the unit can be integrated with the already existing infrastructure.

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Evaluation and analysis of environmentally sustainable extraction of betulin from birch bark with a focus on large-scale industrial feasibility.

Flash pyrolysis of biomass yields a liquid applicable as a fuel oil substitute and as a basis for production of chemicals and fuels. Biomass, being a renewable resource, is foreseen to be in increasing demand. An increased usage may lead to scarcity of biomass and emphasizes the need for high-efficiency conversion processes. In this study, the efficiency and capacity aspects of an integration of pyrolysis oil production with a district heating plant by means of dual fluidized-bed technology has been modeled. Further, fractional condensation of the pyrolysis vapors has been applied, enabling part of the condensation energy to be recovered. The concept shows potential for significant pyrolysis oil production while keeping the delivered power and heat constant. The use of excess heat from the pyrolysis production in the district heating net results in a 10% higher overall efficiency than production without heat supply to the district heating net.