ABSTRACT
The article presents the methodology and applicable data for the generation of life cycle inventory for conventional and alternative processes for base chemical production by process simulation. Addressed base chemicals include lower olefins, BTX aromatics, methanol, ammonia and hydrogen. Assessed processes include conventional chemical production processes from naphtha, LPG, natural gas and heavy fuel oil; feedstock recycling technologies via gasification and pyrolysis of refuse derived fuel; and power-to-X technologies from hydrogen and CO2. Further, process variations with additional hydrogen input are covered. Flowsheet simulation in Aspen Plus is applied to generate datasets with conclusive mass and energy balance under uniform modelling and assessment conditions with available validation data. Process inventory data is generated with no regard to the development stage of the respective technology, but applicable process data with high technology maturity is prioritized for model validation. The generated inventory data can be applied for life cycle assessments. Further, the presented modelling and balancing framework can be applied for inventory data generation of similar processes to ensure comparability in life cycle inventory data.
ABSTRACT
OBJECTIVE: To assess migration of CD34(+) human stem cells to the bone marrow of athymic mice by using magnetic resonance (MR) imaging and Resovist, a contrast agent containing superparamagnetic iron oxide (SPIO) particles. METHODS: All animal and human procedures were approved by our institution's ethics committee, and women had given consent to donate umbilical cord blood (UCB). Balb/c-AnN Foxn1(nu)/Crl mice received intravenous injection of 1 x 10(6) (n=3), 5 x 10(6) (n=3) or 1 x 10(7) (n=3) human Resovist-labelled CD34(+) cells; control mice received Resovist (n=3). MR imaging was performed before, 2 and 24 h after transplantation. Signal intensities of liver, muscle and bone marrow were measured and analysed by ANOVA and post hoc Student's t tests. MR imaging data were verified by histological and immunological detection of both human cell surface markers and carboxydextrancoating of the contrast agent. RESULTS: CD34(+) cells were efficiently labelled by Resovist without impairment of functionality. Twenty-four hours after administration of labelled cells, MR imaging revealed a significant signal decline in the bone marrow, and histological and immunological analyses confirmed the presence of transplanted human CD34(+) cells. CONCLUSION: Intravenously administered Resovist-labelled CD34(+) cells home to bone marrow of mice. Homing can be tracked in vivo by using clinical 1.5-T MR imaging technology.
