Prototypes for automating product system model assembly.

INTRODUCTION: The flexibility of life cycle inventory (LCI) background data selection is increasing with the increasing availability of data, but this comes along with the challenge of using the background data with primary life cycle inventory data. To relieve the burden on the practitioner to create the linkages and reduce bias, this study aimed at applying automation to create foreground LCI from primary data and link it to background data to construct product system models (PSM). METHODS: Three experienced LCA software developers were commissioned to independently develop software prototypes to address the problem of how to generate an operable PSM from a complex product specification. The participants were given a confidential product specification in the form of a Bill of Materials (BOM) and were asked to develop and test prototype software under a limited time period that converted the BOM into a foreground model and linked it with one or more a background datasets, along with a list of other functional requirements. The resulting prototypes were compared and tested with additional product specifications. RESULTS: Each developer took a distinct approach to the problem. One approach used semantic similarity relations to identify best-fit background datasets. Another approach focused on producing a flexible description of the model structure that removed redundancy and permitted aggregation. Another approach provided an interactive web application for matching product components to standardized product classification systems to facilitate characterization and linking. DISCUSSION: Four distinct steps were identified in the broader problem of automating PSM construction: creating a foreground model from product data, determining the quantitative properties of foreground model flows, linking flows to background datasets, and expressing the linked model in a format that could be used by existing LCA software. The three prototypes are complementary in that they address different steps and demonstrate alternative approaches. Manual work was still required in each case, especially in the descriptions of the product flows that must be provided by background datasets. CONCLUSION: The study demonstrates the utility of a distributed, comparative software development, as applied to the problem of LCA software. The results demonstrate that the problem of automated PSM construction is tractable. The prototypes created advance the state of the art for LCA software.

Environmental Benefits of Novel Nonhuman Food Inputs to Salmon Feeds.

Global population growth and changing diets increase the importance, and challenges, of reducing the environmental impacts of food production. Farmed seafood is a relatively efficient way to produce protein and has already overtaken wild fisheries. The use of protein-rich food crops, such as soy, instead of fishmeal in aquaculture feed diverts these important protein sources away from direct human consumption and creates new environmental challenges. Single cell proteins (SCPs), including bacteria and yeast, have recently emerged as replacements for plant-based proteins in salmon feeds. Attributional life cycle assessment is used to compare salmon feeds based on protein from soy, methanotrophic bacteria, and yeast ingredients. All ingredients are modeled at the industrial production scale and compared based on seven resource use and emissions indicators. Yeast protein concentrate showed drastically lower impacts in all categories compared to soy protein concentrate. Bacteria meal also had lower impacts than soy protein concentrate for five of the seven indicators. When these target meals were incorporated into complete feeds the relative trends remain fairly constant, but benefits of the novel ingredients are dampened by high impacts from the nontarget ingredients. Particularly, primary production requirements (PPR) are about equal and constant across all feeds for both analyses since PPR was driven by fishmeal and oil. The bacteria-based feed has the highest climate change impacts due to the use of methane to feed the bacteria who then release carbon dioxide. Overall, the results of this study suggest that incorporating SCP ingredients into salmon feeds can help reduce the environmental impacts of salmon production. Continued improvements in SCP production would further increase the sustainability of salmon farming.

LCA Capability Roadmap: Product System Model Description and Revision.

Life cycle assessment (LCA) practitioners face many challenges in their efforts to describe, share, review, and revise their product system models; and to reproduce the models and results of others. Current Life cycle inventory modeling techniques have weaknesses in the areas of describing model structure; documenting the use of proxy or non-ideal data; specifying allocation; and including modeler's observations and assumptions -- all affecting how the study is interpreted and limiting the reuse of models. Moreover, LCA software systems manage modeling information in different and sometimes non-compatible ways. Practitioners must also deal with licensing, privacy / confidentiality of data, and other issues around data access which impact how a model can be shared. The aim of this SETAC North America working group is to define a roadmap of the technical advances needed to achieve easier LCA model sharing and improve replicability of LCA results among different users in a way that is independent of the LCA software used to compute the results and does not infringe on any licensing restrictions or confidentiality requirements.

Highest risk abandoned, lost and discarded fishing gear.

Derelict abandoned, lost and discarded fishing gear have profound adverse effects. We assessed gear-specific relative risks from derelict gear to rank-order fishing methods based on: derelict gear production rates, gear quantity indicators of catch weight and fishing grounds area, and adverse consequences from derelict gear. The latter accounted for ghost fishing, transfer of microplastics and toxins into food webs, spread of invasive alien species and harmful microalgae, habitat degradation, obstruction of navigation and in-use fishing gear, and coastal socioeconomic impacts. Globally, mitigating highest risk derelict gear from gillnet, tuna purse seine with fish aggregating devices, and bottom trawl fisheries achieves maximum conservation gains. Locally, adopting controls following a sequential mitigation hierarchy and implementing effective monitoring, surveillance and enforcement systems are needed to curb derelict gear from these most problematic fisheries. Primary and synthesis research are priorities to improve future risk assessments, produce the first robust estimate of global derelict gear quantity, and assess the performance of initiatives to manage derelict gear. Findings from this first quantitative estimate of gear-specific relative risks from derelict gear guide the allocation of resources to achieve the largest improvements from mitigating adverse effects of derelict gear from the world's 4.6 million fishing vessels.

Modulation of fluidic resistance and capacitance for long-term, high-speed feedback control of a microfluidic interface.

Existing microfluidic systems can control local chemical environments by directing the interface between laminar flowing streams for applications ranging from subcellular stimulation to fuel cells. However, conventional flow modulation methods have not yet provided a robust and reliable way to dynamically control laminar flow interfaces for very long time periods. Such control is important in biological investigations, since response times for living cells and tissues can be as long as several days. Here, we describe a novel long-term, high-speed approach that employs modulation of fluidic resistance and fluidic capacitance between a fluid reservoir and a microfluidic network with feedback control to enable long-term dynamic control of a microfluidic interface in time and space. Our method involves constricting a narrow tube through a pinching approach to modulate fluidic resistance while also controlling a small variable reservoir in the fluidic network through a squeezing approach to modulate fluidic capacitance. We designed a well-tuned proportional-integral-derivative (PID) controller for the closed-loop control system that resulted in control of pressure for short-term (2 s) and long-term (15 h) experiments. Further, we integrated a pressure-based feedback control approach into this method, which enables both long-term spatiotemporal control of our microfluidic interface at frequencies greater than 1 Hz and a reservoir capacity to enable experiments for longer than 60 days. This long-term and high-speed control is not possible with standard microfluidic laboratory practices. Our system has a diversity of potential applications including long-term cellular studies in cancer metastasis or embryonic development.

Pressure-driven spatiotemporal control of the laminar flow interface in a microfluidic network.

We describe a system for dynamically adjusting the position of the laminar interface between two fluids flowing inside a microfluidic channel, with a time response of less than 0.1 s, through feedback control of the channel inlet pressure.

Probing cellular dynamics with a chemical signal generator.

Observations of material and cellular systems in response to time-varying chemical stimuli can aid the analysis of dynamic processes. We describe a microfluidic "chemical signal generator," a technique to apply continuously varying chemical concentration waveforms to arbitrary locations in a microfluidic channel through feedback control of the interface between parallel laminar (co-flowing) streams. As the flow rates of the streams are adjusted, the channel walls are exposed to a chemical environment that shifts between the individual streams. This approach can be used to probe the dynamic behavior of objects or substances adherent to the interior of the channel. To demonstrate the technique, we exposed live fibroblast cells to ionomycin, a membrane-permeable calcium ionophore, while assaying cytosolic calcium concentration. Through the manipulation of the laminar flow interface, we exposed the cells' endogenous calcium handling machinery to spatially-contained discrete and oscillatory intracellular disturbances, which were observed to elicit a regulatory response. The spatiotemporal precision of the generated signals opens avenues to previously unapproachable areas for potential investigation of cell signaling and material behavior.