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Most students enter college without any exposure to polymer science, which leads to the poor understanding and slow implementation of plastics recycling programs in the United States. To address the knowledge gap in chemical recycling, we introduce a 2-part laboratory experiment that was conducted in multiple high schools and public outreach events to demonstrate the depolymerization of PET via aminolysis and the remanufacturing of cleaved PET fragments into a new aramid polymer. Student experiences were evaluated with two post-lab assignments. 

We introduce MechSense, 3D-printed rotary encoders that can be fabricated in one pass alongside rotational mechanisms, and report on their angular position, direction of rotation, and speed. MechSense encoders utilize capacitive sensing by integrating a floating capacitor into the rotating element and three capacitive sensor patches in the stationary part of the mechanism. Unlike existing rotary encoders, MechSense does not require manual assembly but can be seamlessly integrated during design and fabrication. Our MechSense editor allows users to integrate the encoder with a rotating mechanism and exports files for 3D-printing. We contribute a sensor topology and a computational model that can compensate for print deviations. Our technical evaluation shows that MechSense can detect the angular position (mean error: 1.4°) across multiple prints and rotations, different spacing between sensor patches, and different sizes of sensors. We demonstrate MechSense through three application examples on 3D-printed tools, tangible UIs, and gearboxes. 

Abstract Despite the availability of Cas9 variants with varied protospacer-adjacent motif (PAM) compatibilities, some genomic loci—especially those with pyrimidine-rich PAM sequences—remain inaccessible by high-activity Cas9 proteins. Moreover, broadening PAM sequence compatibility through engineering can increase off-target activity. With directed evolution, we generated four Cas9 variants that together enable targeting of most pyrimidine-rich PAM sequences in the human genome. Using phage-assisted noncontinuous evolution and eVOLVER-supported phage-assisted continuous evolution, we evolved Nme2Cas9, a compact Cas9 variant, into variants that recognize single-nucleotide pyrimidine-PAM sequences. We developed a general selection strategy that requires functional editing with fully specified target protospacers and PAMs. We applied this selection to evolve high-activity variants eNme2-T.1, eNme2-T.2, eNme2-C and eNme2-C.NR. Variants eNme2-T.1 and eNme2-T.2 offer access to N₄TN PAM sequences with comparable editing efficiencies as existing variants, while eNme2-C and eNme2-C.NR offer less restrictive PAM requirements, comparable or higher activity in a variety of human cell types and lower off-target activity at N₄CN PAM sequences. 

Water quality analysis of Philadelphia County surface waters have indicated that storm events alter the concentrations of pollutants such as polycyclic aromatic hydrocarbons (PAHs), antibiotics, heavy metals, and other pollutants, which could impact aquatic organisms' diversity as well as human health. However, there is limited knowledge regarding the microbial communities in these environments and their responses to these pollutants. To address this knowledge gap, culturing and analysis of genomes isolated from surface water samples was carried out at two different time points: one under average conditions (SW1) and another three days after a storm event (SW2). Colorimetric water quality assays were also employed to assess the levels of common pollutants in waterways and observe alterations in the relative concentrations of various chemicals in the Schuylkill River after storm events. Gram staining, and culture analysis of isolated colonies from surface waters in Philadelphia County waterways was performed to understand microbial diversity and the principles of bacterial identification. Genomic DNA was extracted from bacteria concentrated via filtration. PCR amplification of the 16s rRNA gene was performed in preparation for genomic sequencing. Genomic sequencing of samples from various waterways was performed and analyzed using bioinformatics software to identify microorganisms and classify taxa. The results demonstrate that storm events influence the diversity of microorganisms in the Delaware River Watershed. Further analysis of pollutant levels and the metagenomic data will be needed to further elucidate the correlation between specific pollutants and potential pathogens as well as the influence of said pollutants on microbial diversity. 

“Smart” water systems are transforming the field of stormwater management by enabling real-time monitoring and control of previously static infrastructure. While the localized benefits of active control are well-established, the potential for system-scale control of watersheds is poorly understood. This study shows how a real-world smart stormwater system can be leveraged to shape streamflow within an urban watershed. Specifically, we coordinate releases from two internet-controlled stormwater basins to achieve desired control objectives downstream—such as maintaining the flow at a set-point, and generating interleaved waves. In the first part of the study, we describe the construction of the control network using a low-cost, open-source hardware stack and a cloud-based controller scheduling application. Next, we characterize the system’s control capabilities by determining the travel times, decay times, and magnitudes of various waves released from the upstream retention basins. With this characterization in hand, we use the system to generate two desired responses at a critical downstream junction. First, we generate a set-point hydrograph, in which flow is maintained at an approximately constant rate. Next, we generate a series of overlapping and interleaved waves using timed releases from both retention basins. We discuss how these control strategies can be used to stabilize flows, thereby mitigating streambed erosion and reducing contaminant loads into downstream waterbodies. 

Leveraging recent advances in technologies surrounding the Internet of Things , “smart” water systems are poised to transform water resources management by enabling ubiquitous real-time sensing and control. Recent applications have demonstrated the potential to improve flood forecasting, enhance rainwater harvesting, and prevent combined sewer overflows. However, adoption of smart water systems has been hindered by a limited number of proven case studies, along with a lack of guidance on how smart water systems should be built. To this end, we review existing solutions, and introduce open storm —an open-source, end-to-end platform for real-time monitoring and control of watersheds. Open storm includes (i) a robust hardware stack for distributed sensing and control in harsh environments (ii) a cloud services platform that enables system-level supervision and coordination of water assets, and (iii) a comprehensive, web-based “how-to” guide, available on open-storm.org, that empowers newcomers to develop and deploy their own smart water networks. We illustrate the capabilities of the open storm platform through two ongoing deployments: (i) a high-resolution flash-flood monitoring network that detects and communicates flood hazards at the level of individual roadways and (ii) a real-time stormwater control network that actively modulates discharges from stormwater facilities to improve water quality and reduce stream erosion. Through these case studies, we demonstrate the real-world potential for smart water systems to enable sustainable management of water resources. 

The goal of this project is to conduct the first geographically distributed, low-frequency skywave propagation measurements during a solar eclipse. There is a lack of knowledge about how radio waves below frequencies of 500 kHz are affected by a total eclipse and a lack of experimental data reflecting these low-frequency radio wave transmissions at geographically diverse locations during an eclipse. A low-frequency band receiver system for people across the United States to assemble and use is designed, allowing for a crowd-sourced collection of measurements of relative signal strength of the WWVB and Dixon low-frequency station signals during the eclipse over North America on August 21, 2017.