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Two types of catalytic sites of In2O3-Co3O4/CeO2 and their synergy for highly selective CO2 hydrogenation to methanol
No full textThe increasing concentration of greenhouse gases, specifically CO2, requires innovative mitigation approaches. Catalytic CO2 reduction shows potential for producing high-value-added products from CO2, but the poor catalyst activity and product selectivity remain significant challenges. Oxygen vacancies and the interaction between the support and active components significantly influence the catalytic reactivity of a catalyst. Herein, we demonstrated a novel strategy to design highly efficient catalysts; namely, the reducibility of CeO2 was exploited to tune the In2O3-Co3O4 catalyst for CO2 hydrogenation, creating synergetic double-type active sites that the OV1 oxygen defects (generated by hydrogen reduction) on CeO2 surface as active sites for CO2 adsorption and the In-Co-Ce interfaces as active sites for hydrogenation of the adsorbed CO2 to methanol via formate intermediates. Consequently, an excellent methanol selectivity of 74 % was achieved for CO2 hydrogenation, leading to a very high methanol space–time yield of 276.8 mg∙h−1∙gIn-Co−1 under mild reaction conditions (3 MPa, 280 °C, 2400 mL∙gcat−1∙h−1), which is 4.8-fold higher than that without CeO2. This study highlights the highly synergistic effects of two types of catalytic sites of the CeO2 supported In2O3-Co3O4 catalyst and reveals a new pathway for designing new catalysts for more efficient CO2 hydrogenation to methanol (CHTM)
Accurate computation of scattering poles of acoustic obstacles with impedance boundary conditions
No full textWe propose a computation method for scattering poles of impedance obstacles. Boundary integral equations are used to formulate the problem. It is shown that the scattering poles are the eigenvalues of some integral operator. Then we employ the Nyström method to discretize the integral operator and obtain a nonlinear matrix eigenvalue problem. The eigenvalues are computed using a multistep parallel spectral indicator method. Numerical examples demonstrate the high accuracy of the proposed method and can serve as the benchmarks. Our study provides a practical approach and can be extended to other scattering problems. This paper continues our previous study on the computation method for scattering poles of sound-soft obstacles
RSVP Keyboard with Inquiry Preview: mixed performance and user experience with an adaptive, multimodal typing interface combining EEG and switch input
No full textOBJECTIVE: The RSVP Keyboard is a non-implantable, event-related potential-based brain-computer interface (BCI) system designed to support communication access for people with severe speech and physical impairments. Here we introduce Inquiry Preview, a new RSVP Keyboard interface incorporating switch input for users with some voluntary motor function, and describe its effects on typing performance and other outcomes. APPROACH: Four individuals with disabilities participated in the collaborative design of possible switch input applications for the RSVP Keyboard, leading to the development of Inquiry Preview and a method of fusing switch input with language model and electroencephalography (EEG) evidence for typing. Twenty-four participants without disabilities and one potential end user with incomplete locked-in syndrome took part in two experiments investigating the effects of Inquiry Preview and two modes of switch input on typing accuracy and speed during a copy-spelling task. MAIN RESULTS: For participants without disabilities, Inquiry Preview and switch input tended to worsen typing performance compared to the standard RSVP Keyboard condition, with more consistent effects across participants for speed than for accuracy. However, there was considerable variability, with some participants demonstrating improved typing performance and better user experience with Inquiry Preview and switch input. Typing performance for the potential end user was comparable to that of participants without disabilities. He typed most quickly and accurately with Inquiry Preview and switch input and gave favorable user experience ratings to those conditions, but preferred standard RSVP Keyboard. SIGNIFICANCE: Inquiry Preview is a novel multimodal interface for the RSVP Keyboard BCI, incorporating switch input as an additional control signal. Typing performance and user experience and preference varied widely across participants, reinforcing the need for flexible, customizable BCI systems that can adapt to individual users. CLINICALTRIALS: gov Identifier: NCT04468919
Metal-rich lacustrine sediments from legacy mining perpetuate copper exposure to aquatic-riparian food webs
Get PDFHistoric copper mining left a legacy of metal-rich tailings resulting in ecological impacts along and within Torch Lake, an area of concern in the Keweenaw Peninsula, Michigan, USA. Given the toxicity of copper to invertebrates, this study assessed the influence of this legacy on present day nearshore aquatic and terrestrial ecosystems. We measured the metal (Co, Cu, Ni, Zn, Cd) and metalloid (As) concentrations in sediment, pore water, surface water, larval and adult insects, and two riparian spider taxa collected from Torch Lake and a nearby reference lake. Overall, elevated metal and metalloid concentrations, particularly Cu, were measured in all sediment samples and some surface and pore water samples collected from Torch Lake. For instance, Cu concentrations in the Torch Lake sediment were ∼200% higher than the reference lake and all measured concentrations exceeded predicted effects concentrations by at least ninefold. Within larval insect tissues, we observed 160% higher Cu concentrations than measured in the reference lake, and Cu was the only measured element above predicted effects concentrations in Torch Lake. Adult insects collected at both lakes had similar metal concentrations irrespective of exposure levels. Yet we found 100% higher copper concentrations in Torch Lake riparian spiders, demonstrating elevated exposure risk to insectivores across the aquatic-terrestrial boundary. Our results highlight that other metals in the mixture may not be as concerning to adjacent riparian ecosystems, but copper remains a contaminant of concern in Torch Lake 60 years after mining ceased
Towards Developing GLUT2 Specific Probes for Biochemical and Biomedical Applications
No full textFacilitated Glucose transporters (GLUTs) are membrane proteins responsible for the uptake of simple sugars and other structurally similar metabolites in all mammalian cells. One of the hallmarks of cancer is dysfunctional sugar metabolism, known as the Warburg effect, and one of the manifestations of that effect is abnormal GLUT expression. There are 14 known GLUT proteins with different expression patterns in different tissues, and tumors tend to express certain GLUTs that are not present in surrounding healthy tissue. Therefore, selective targeting of GLUTs presents a potentially powerful tool for diagnostics and treatment of cancer and other diseases. This has been an active research area since the 1950s, and recently, selective targeting of GLUT5 was achieved, due to its unique substrate preference. GLUT2 also has a distinct substrate preference, which we attempted to exploit to achieve selective targeting. First, we ran computational models of GLUT2 taking up its highest affinity substrate, glucosamine, to understand which residues play a key role in the substrate recognition and uptake. Next, we screened several fluorescent conjugated glucosamine derivatives in silico to determine the structure activity relationship. And then we synthesized those derivatives in the lab to measure their uptake on live tumor cells that overexpress GLUT2. Those measurements allowed us to verify the validity of our computational model findings and the validity of our hypothesized GLUT2 binding preference, a key step towards achieving GLUT2 selectivity. Additionally, during the glucosamine derivative synthesis process, the limited number of modifications that were possible on existing glucosamine molecules, and the prohibitive cost of other glucosamine-like amino sugars and derivatives inspired the development of a novel viii synthetic pathway to sugars and amino sugars. This synthesis builds the sugar molecule one carbon atom at a time while controlling stereochemistry and substitution, enabling the synthesis of hundreds of possible sugars with different substitution, stereochemistry, and length. The utility of this synthetic approach to sugars potentially extends far beyond the scope of this investigation into GLUT2, and combined with selective targeting of GLUT2, opens the potential for many different biochemical and biomedical applications in the field of oncology and beyond
Cloud microphysical response to entrainment of dry air containing aerosols
Get PDFImpacts of aerosol particles on clouds, precipitation, and climate remain one of the significant uncertainties in climate change. Aerosol particles entrained at cloud top and edge can affect cloud microphysical and macrophysical properties, but the process is still poorly understood. Here we investigate the cloud microphysical responses to the entrainment of aerosol-laden air in the Pi convection-cloud chamber. Results show that cloud droplet number concentration increases and mean radius of droplets decreases, which leads to narrower droplet size distribution and smaller relative dispersion. These behaviors are generally consistent with the scenario expected from the first aerosol-cloud indirect effect for a constant liquid water content (L). However, L increases significantly in these experiments. Such enhancement of L can be understood as suppression of droplet sedimentation removal due to small droplets. Further, an increase in aerosol concentration from entrainment reduces the effective radius and ultimately increases cloud optical thickness and cloud albedo, making the clouds brighter. These findings are of relevance to the entrainment interface at stratocumulus cloud top, where modeling studies have suggested sedimentation plays a strong role in regulating L. Therefore, the results provide insights into the impacts of entrainment of aerosol-laden air on cloud, precipitation, and climate
Overview of biodegradable materials for bone repair and osteosarcoma treatment: From bulk to scaffolds
No full textOsteosarcoma, the most common type of malignant bone tumor that affects growing bones in teenagers and children, has become a significant challenge for medical science. The combination of chemotherapy and surgery has been the standard treatment strategy for decades. However, concerns about tumor recurrence and the toxic effects of the drugs continue to drive materials scientists to develop multifunctional scaffolds that can simultaneously support bone regeneration and prevent tumor recurrence. Emergent multifunctional scaffolds have the potential to foster essential and dynamic cellular communication, which can directly target, signal, stimulate, and enhance the body\u27s natural bone repair response. This review emphasizes the mechanisms involved and highlights various technologies and manufacturing processes that align with the capability of these scaffolds to effectively promote bone repair, especially in the presence of osteosarcoma. Additionally, the review summarizes the current state of knowledge regarding scaffolds based on magnesium (Mg), zinc (Zn), and iron (Fe), as well as the antitumor properties of their corrosion products. The review also discusses the therapeutic potential of Mg-, Zn-, and Fe-based materials in inhibiting osteosarcoma cell proliferation. The article elaborates on the main research challenges and prospects of biodegradable materials for bone repair and osteosarcoma treatment
CHARACTERIZATION OF KRYPTON PERFORMANCE IN A LABORATORY 300 W MAGNETICALLY SHIELDED HALL-EFFECT THRUSTER
Get PDFXenon has long been the propellant of choice in Hall Thrusters; however, significant work has been performed to produce thrusters capable of utilizing alternate propellants due to xenon’s price and scarcity. Krypton is the most similar alternative propellant to xenon. This work examines the performance of a sub-kilowatt magnetically shielded Hall Thruster operating on both xenon and krypton. Krypton produced lower thrust, specific impulse, and was less efficient than xenon. Specifically, the absolute xenon-krypton efficiency gap was 6 to 24 % . Krypton’s inferior efficiency is primarily attributable to differences in mass utilization and beam divergence losses. The impacts of elevating discharge voltage and current were explored. These efforts showed elevated discharge voltage minimally improves krypton performance, whereas elevated discharge current significantly improves krypton performance. However, neither closes the xenon-krypton efficiency gap. This work also suggests that cathode propellant influences the thruster’s cathode coupling, voltage utilization, and divergence efficiencies
Utilizing Biometrics and Blockchain for Enhanced Security of Remote Patient Monitoring (RPM) Data Sharing
Get PDFAdvancements in Artificial Intelligence (AI) and Internet of Medical Things (IoMT) technologies have significantly revolutionized the conventional healthcare systems. Through the integration of smart devices, medical sensors, and communication technology, IoMT provides real-time patient’s monitoring data for healthcare providers, thus promoting accurate and timely clinical decisions for patient-centric care. The current healthcare sector is evolving to a connected ecosystem with connectivity and intelligence. While it also incurs increasing security and privacy concerns as integrating IoMT generated patient monitoring data into healthcare information systems. Both blockchain and biometrics are measures that have established reputable names in the security realm. When evaluating a market known to be especially vulnerable to cyber attacks, such as healthcare, it is imperative to devise solutions that have multiple layers of trusted security mechanisms.
This thesis explores and verifies the security of combining both biometrics and blockchain being utilized to protect remote patient monitoring (RPM) data, one of healthcare\u27s most vulnerable sectors of information. The proposed framework combines the immutability of data hashing and biometric authentication to verify the identity of the patient as the sender of the data to ensure the integrity of the source. The data owners (patients) rely on smart contract-based tokens to record hash values of their biometric information (e.g, fingerprint), which provides a decentralized identity authentication. In addition, data owners leverage a merkle tree based data batch validation to verify integrity and authenticity for storage and sharing of patient monitoring data (e.g., 7-days rest heart rate). The merkle root is stored on the distributed ledger and can later be retrieved by an authorized party by way of tokens. This framework also integrates access control token to address the concerns of unauthorized users that manipulate RPM data in transit and at rest. A proof-of-concept prototype is implemented and test on a private Ethereum network. Experimental results demonstrate the feasibility of the proposed framework to provide a decentralized and trustworthy data sharing platform for IoMT-based RPM applications
CLIMATE PLANNING, ENERGY SOVEREIGNTY, AND ELECTRIC VEHICLE PERCEPTIONS AMONG MICHIGAN’S TRIBAL NATIONS
Get PDFClimate change will especially impact marginalized communities and communities with less government support for funding climate adaptation actions. The first chapter of this report focuses on climate change responses, specifically Tribal Nations in the state of Michigan. In the current U.S. context, funding for large climate change mitigation and adaptation projects in Tribal Nations can be achieved through federal funding from the CPRG (Climate Pollution Reduction Grant), which requires an established PCAP (Priority Climate Action Plans) to guide decision making in alignment with identified priorities. I discuss the importance of Tribal sovereignty, the potential implications of its inclusion and exclusion within climate planning documentation, and the direct and indirect mentions of sovereignty, Traditional Ecological Knowledge (TEK), and Nature-based Solutions (NbS) within PCAPs developed by the Tribal Nations in the state of Michigan. The second chapter of my report focuses on a survey that was created and deployed to two Tribal Nations in the colonial state of Michigan located near Michigan Technological University that noted that they would like to implement EV (electric vehicle) infrastructure in the first cohort of the WGLEN (Western Great Lakes Electric Nation) project; this chapter of the report will go over the findings from using an engagement form to better understand perceptions of EVs and will focus solely on the Tribal Nations in the state of Michigan, as this is where the engagement forms were deployed. Results indicate that the rurality of Tribal Nations in the Upper Peninsula of Michigan may contribute to the lack of knowledge, negative perceptions and opinions of EVs