Thermal Management for High Power Cubesats

Thermal management systems for small satellites have traditionally been neglected entirely or only considered as an afterthought. This approach to small satellite systems design is no longer acceptable as technology has matured over the past decade and payload operational power has increased. Higher power leads to an increase in waste heat generated on-orbit. Trends in industry indicate that power demand for small satellite class (10-100 kg) can reach up to kilowatt range in the near future. A scalable Thermal Management System (TMS) has been developed which is applicable to small satellites ranging from CubeSats to ESPA class spacecraft. The TMS can handle up to 1 kW of waste heat. The TMS solution leverages breakthroughs in additive manufacturing, flexible heat pipes, and material science to dissipate extremely large quantities of waste heat in a small SWaP system. The system consists of: A rollout deployable radiator maximizing radiation of heat into space. Structurally integrated heat pipes for efficient heat transport; Energy storage based on a Phase Change Material (PCM) for mitigation of extreme temperature excursions to peak power The TMS is a modular system, flexible to be customized to particular mission requirements and spacecraft form factor. The paper discusses the TMS concept, components, and challenges. Performance evaluation is demonstrated. The TMS development has been sponsored by the United States Air Force Research Laboratory

Significantly Enhanced DNA Thermal Stability Resulting from Porphyrin H-Aggregate Formation in the Minor Grove of the Duplex

(Figure Presented) Too groovy: The covalent attachment of up to four porphyrins to complementary strands led to the formation of DNA porphyrin zippers with significantly increased DNA duplex stability. This is a result of H-aggregate formation in the minor groove. To the best of our knowledge this is the first report showing such a significant thermal duplex stabilization

Three-Dimensional Nanostructured Palladium with Single Diamond Architecture for Enhanced Catalytic Activity

Fuel cells are a key new green technology that have applications in both transport and portable power generation. Carbon-supported platinum (Pt) is used as an anode and cathode electrocatalyst in low-temperature fuel cells fueled with hydrogen or low-molecular-weight alcohols. The cost of Pt and the limited world supply are significant barriers to the widespread use of these types of fuel cells. Comparatively, palladium has a 3 times higher abundance in the Earth’s crust. Here, a facile, low-temperature, and scalable synthetic route toward three-dimensional nanostructured palladium (Pd) employing electrochemical templating from inverse lyotropic lipid phases is presented. The obtained single diamond morphology Pd nanostructures exhibited excellent catalytic activity and stability toward methanol, ethanol, and glycerol oxidation compared to commercial Pd black, and the nanostructure was verified by small-angle X-ray scattering, scanning tunneling electron microscopy, and cyclic voltammetry

Prevalence of frailty among kidney transplant candidates and recipients in the United States: Estimates from a National Registry and Multicenter Cohort Study

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/154612/1/ajt15709.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/154612/2/ajt15709_am.pd

'Parametric Matter':Pushing’ Updates into Materials and theImplications of Legacy and Lag

This paper discusses an ongoing interdisciplinary research project that develops a design and fabrication approach termed; tunable environments. This is an explorative approach, which enables updates from a digital parametric interface to be ‘pushed' into a 2D, 18x18 cm material sample, by modulating stimuli, so multi properties can be updated/tuned at high resolutions. Our prototype explores how iterative updates can be achieved, which can be temporarily frozen in time. This opens up the idea of creating Parametric Matter/circular materials, which could reduce waste that can be attributed to typical linear processes. Additionally, highly bespoke, ‘time-based’ structures could be achieved. However new implications for design and fabrication arise based on: time-lag of materials, a legacy of interactions, resetting materials as well as challenges of determining associations and desirable material properties

Using geographically weighted regression to explore the spatially heterogeneous spread of bovine tuberculosis in England and Wales

An understanding of the factors that affect the spread of endemic bovine tuberculosis (bTB) is critical for the development of measures to stop and reverse this spread. Analyses of spatial data need to account for the inherent spatial heterogeneity within the data, or else spatial autocorrelation can lead to an overestimate of the significance of variables. This study used three methods of analysis—least-squares linear regression with a spatial autocorrelation term, geographically weighted regression (GWR) and boosted regression tree (BRT) analysis—to identify the factors that influence the spread of endemic bTB at a local level in England and Wales. The linear regression and GWR methods demonstrated the importance of accounting for spatial differences in risk factors for bTB, and showed some consistency in the identification of certain factors related to flooding, disease history and the presence of multiple genotypes of bTB. This is the first attempt to explore the factors associated with the spread of endemic bTB in England and Wales using GWR. This technique improves on least-squares linear regression approaches by identifying regional differences in the factors associated with bTB spread. However, interpretation of these complex regional differences is difficult and the approach does not lend itself to predictive models which are likely to be of more value to policy makers. Methods such as BRT may be more suited to such a task. Here we have demonstrated that GWR and BRT can produce comparable outputs

Toward a stoichiometric framework for evolutionary biology. Oikos

2005. Toward a stoichiometric framework for evolutionary biology. Á/ Oikos 109: 6 Á/17. Ecological stoichiometry, the study of the balance of energy and materials in living systems, may serve as a useful synthetic framework for evolutionary biology. Here, we review recent work that illustrates the power of a stoichiometric approach to evolution across multiple scales, and then point to important open questions that may chart the way forward in this new field. At the molecular level, stoichiometry links hereditary changes in the molecular composition of organisms to key phenotypic functions. At the level of evolutionary ecology, a simultaneous focus on the energetic and material underpinnings of evolutionary tradeoffs and transactions highlights the relationship between the cost of resource acquisition and the functional consequences of biochemical composition. At the macroevolutionary level, a stoichiometric perspective can better operationalize models of adaptive radiation and escalation, and elucidate links between evolutionary innovation and the development of global biogeochemical cycles. Because ecological stoichiometry focuses on the interaction of energetic and multiple material currencies, it should provide new opportunities for coupling evolutionary dynamics across scales from genomes to the biosphere