Spatially Explicit Life Cycle Assessment: Opportunities and challenges of wastewater-based algal biofuels in the United States

This work presented a Spatially-Explicit-High-Resolution Life Cycle Assessment (SEHR-LCA) model for wastewater-based algal biofuel production, by integrating life cycle assessment, GIS analysis, and site-specific Wastewater Treatment Plants (WWTPs) data analysis. Wastewater resources, land availability, and meteorological variation were analyzed for algae cultivation. Three pathways, Microwave Pyrolysis, hydrothermal liquefaction, and lipid extraction were modeled for bio-oil conversion. This model enables the assessment of seasonal and site-specific variations in productivity and environmental impacts of wastewater-based algal bio-oil across the whole U.S. Model results indicate that wastewater-based algal bio-oil can provide an opportunity to increase national biofuel output. The potential production of algal bio-oil can reach to 0.98 billion gallon/yr, nearly 20% of advanced biofuel projection as outlined in the U.S. Energy Independence and Security Act (EISA) of 2007. LCA results shows significant variations among different locations, WWTPs, and operational seasons. Although not competitive to conventional fossil fuel in energy efficiency, wastewater-based algal biofuel could offer significant benefit in controlling GHG emissions. However, spatial analysis shows that only 61% of the total wastewater could be used, based on current land use efficiency for algae cultivation and land availability around each WWTP in a radius where algal biofuel production is energy positive (energy output N energy input). These results indicate that land availability could be a significant challenge for wastewater-based algal biofuels that have not been considered in previous studies. They also suggest that improvement should be made in technological development and system design to increase energy and land use efficiency for full potential of wastewater as a promising resource for algal biofuel production. Although focusing on the U.S. as the case study, the developed methodology could be used for spatially explicit analysis of algal biofuel integrated with wastewater on macro-scale in other regions as well

Single DNA conformations and biological function

From a nanoscience perspective, cellular processes and their reduced in vitro imitations provide extraordinary examples for highly robust few or single molecule reaction pathways. A prime example are biochemical reactions involving DNA molecules, and the coupling of these reactions to the physical conformations of DNA. In this review, we summarise recent results on the following phenomena: We investigate the biophysical properties of DNA-looping and the equilibrium configurations of DNA-knots, whose relevance to biological processes are increasingly appreciated. We discuss how random DNA-looping may be related to the efficiency of the target search process of proteins for their specific binding site on the DNA molecule. And we dwell on the spontaneous formation of intermittent DNA nanobubbles and their importance for biological processes, such as transcription initiation. The physical properties of DNA may indeed turn out to be particularly suitable for the use of DNA in nanosensing applications.Comment: 53 pages, 45 figures. Slightly revised version of a review article, that is going to appear in the J. Comput. Theoret. Nanoscience; some typos correcte

Changes in Relative Ability as a Determinant of the U.S. College Premium

We develop a macroeconomic framework to estimate the importance of fluctuations in relative ability in accounting for trends in the college premium in the United States since 1965. The theoretical scaffolding is a heterogeneous agent model with two dimensions of ability and endogenous schooling choice, with exogenous skill-biased technological change (SBTC), college tuition, and noneconomic social forces. We solve for conditions under which SBTC reduces the relative ability of college educated workers, and show that these conditions are met in the data. We attribute the drop in the college premium over the 1970s to a 25.5% drop in the mean relative quality of college-educated workers from 1968 to 1977. We find that SBTC explains about two thirds of the increase in college attendance since 1965, and that absent both supply shifts and a supply response to SBTC, the relative wage of highly educated workers would have been 77.1% larger in 2013

Identification of Structural Parameters Based on HHT and NExT

Signal processing approaches are widely used in the field of earthquake engineering, especially in the identification of structural modal parameters. Hilbert-Huang Transformation (HHT) is one new signal processing approach, which can be used to identify the modal frequency, damping ratio, mode shape, even the interlayer stiffness of the shear-type structure, incorporating with Natural Excitation Technique (NExT) method to take information from the response records of the structure. The stiffness of the structure is of great importance to judge the loss of its bearing capacity after earthquake. However, all of modal parameters are required to calculate the stiffness of the structure by use of HHT and NExT, which means that the response records shall contain all of modal information. However, it has been found that the responses of the structure recorded only contain the former order modal information; even it is excited by earthquake. Therefore, it is necessary to found a formula (formulas) to calculate the stiffness only using limited modal parameters. In this paper, the calculation formulas of the interlayer stiffness of shear-type structure are derived by using of the flexibility method, which indicate that all of interlayer stiffnesses could be worked out as long as any one set of modal parameters is obtained. After that, Taking Sheraton-Universal Hotel subjected to North Bridge earthquake in 1994 as an example, HHT and NExT are used to identify its modal parameters, the derived formulas are used to calculate the interlayer stiffnesses, and their applicability and accuracy are verified

Identifying hotspots and management of critical ecosystem services in rapidly urbanizing Yangtze River Delta Region, China

Rapid urbanization has altered many ecosystems, causing a decline in many ecosystem services, generating serious ecological crisis. To cope with these challenges, we presented a comprehensive framework comprising five core steps for identifying and managing hotspots of critical ecosystem services in a rapid urbanizing region. This framework was applied in the case study of the Yangtze River Delta (YRD) Region. The study showed that there was large spatial heterogeneity in the hotspots of ecosystem services in the region, hotspots of supporting services and regulating services aggregately distributing in the southwest mountainous areas while hotspots of provisioning services mainly in the northeast plain, and hotspots of cultural services widespread in the waterbodies and southwest mountainous areas. The regionalization of the critical ecosystem services was made through the hotspot analysis. This study provided valuable information for environmental planning and management in a rapid urbanizing region and helped improve China's ecological redlines policy at regional scale

Genuine nonlocality of generalized GHZ states in many-partite systems

A set of orthogonal multipartite quantum states is said to be distinguishability-based genuinely nonlocal (also genuinely nonlocal, for abbreviation) if the states are locally indistinguishable across any bipartition of the subsystems. In this work, we study the (distinguishability-based) genuine nonlocality of the generalized GHZ states, primarily for the case when a large number of partites are considered. For the N-qubit case, we show that genuinely nonlocal subsets of the GHZ basis with cardianlity {\Theta}(2^(N/2)) exist. We also generalize this result to the cases when d > 2 is an even number