THE SUPPORTED GOLD CATALYSTS FOR CLOSED CYCLE CO_2 LASER

Sealed-off carbon dioxide lasers encounter problem of dissociation of CO2, Which causes the output power to fall. Reformation of CO2 is therefore essential for long life CO2 lasers. Au/Fe2O3 and Au/NiFe2O4 are promising candidates for this application.

Dynamic simulation of a space gas-cooled reactor power system with a closed Brayton cycle

Space nuclear reactor power(SNRP)using a gas-cooled reactor(GCR)and a closed Brayton cycle(CBC)is the ideal choice for future high-power space missions.To investigate the safety characteristics and develop the control strategies for gas-cooled SNRP,transient models for GCR,energy conversion unit,pipes,heat exchangers,pump and heat pipe radiator are established and a system analysis code is developed in this paper.Then,analyses of several operation conditions are performed using this code.In full-power steady-state operation,the core hot spot of 1293 K occurs near the upper part of the core.If 0.4$reactivity is introduced into the core,the maximum temperature that the fuel can reach is 2059 K,which is 914 K lower than the fuel melting point.The system finally has the ability to achieve a new steady-state with a higher reactor power.When the GCR is shut down in an emergency,the residual heat of the reactor can be removed through the conduction of the core and radiation heat transfer.The results indicate that the designed GCR is inherently safe owing to its negative reactivity feedback and passive decay heat removal.This paper may provide valuable references for safety design and analysis of the gas-cooled SNRP coupled with CBC.

A concept to support the transformation from a linear to circular carbon economy:net zero emissions,resource efficiency and conservation through a coupling of the energy,chemical and waste management sectors

Coal and carbon-containing waste are valuable primary and secondary carbon carriers.In the current dominant linear economy,such carbon resources are generally combusted to produce electricity and heat and as a way to resolve a nation’s waste issue.Not only is this a wastage of precious carbon resources,which can be chemically utilized as raw materials for production of other value-added goods,it is also contrary to international efforts to reduce carbon emissions and increase resource efficiency and conservation.This article presents a concept to support the transformation from a linear‘one-way cradle to grave manufacturing model’toward a circular carbon economy.The development of new and sustainable value chains through the utilization of coal and waste as alternative raw materials for the chemical industry via a coupling of the energy,chemical and waste management sectors offers a viable and future-oriented perspective for closing the carbon cycle.Further benefits also include a lowering of the carbon footprint and increasing resource efficiency and conservation of primary carbon resources.In addition,technological innovations and developments that are necessary to support a successful sector coupling will be identified.To illustrate our concept,a case analysis of domestic coal and waste as alternative feedstock to imported crude oil for chemical production in Germany will be presented.Last but not least,challenges posed by path dependency along technological,institutional and human dimensions in the sociotechnical system for a successful transition toward a circular carbon economy will be discussed.

Comment： Closing phosphorus cycle from natural waters： re-capturing phosphorus through an integrated water-energy-food strategy

Phosphorus （P） reserve, largely derived from phosphate rock, is essential for crop growth to support the growing world population. However, a significant proportion of phosphorus used as a fertilizer runs into natural waters, causing eutro- phication and ecological damage. Moreover, most P in the food is eventually discharged as waste after being digested by human and animals. Thus, industrial activities have created a one-way flow of non-renewable P from rocks to farms to lakes, rivers and oceans.