Polymers and other oxidizable materials used on the exterior of spacecraft in the low Earth orbit (LEO) space environment can be eroded away by reaction with atomic oxygen (AO). For spacecraft design, it is important to know the LEO AO erosion yield, Ey (volume loss per incident oxygen atom), of materials susceptible to AO erosion. The Stressed Polymers Experiment was developed and flown as part of the Materials International Space Station Experiment 6 (MISSE 6) to compare the AO erosion yields of stressed and non-stressed polymers to determine if erosion is dependent upon stress while in LEO. The experiment contained 36 thin film polymer samples that were exposed to ram AO for 1.45 years. This paper provides an overview of the Stressed Polymers Experiment with details on the polymers flown, the characterization techniques used, the AO fluence, and the erosion yield results. The MISSE 6 data are compared to data for similar samples flown on previous MISSE missions to determine fluence or solar radiation effects on erosion yield.

关键词：地球轨道环境；航天环境；氧原子；侵蚀；辐射效应

查看摘要 索取原文[30页]

Olefin polymerization catalysts containing redox-active moieties that may be tuned in situ via electrochemical or chemical oxidation and reduction were synthesized and examined. The redox capable functionalities were incorporated into specifically chosen ligand frameworks and metallated using organometallic reagents so as to produce precatalysts that could be activated using methylaluminoxane, borane, or boronate-based activators. Those catalysts were shown to be active toward olefin polymerizations,their electrochemistry studied, and their in situ switchability is currently underway yielding many promising results.

关键词：催化；烯烃；催化剂；中性镍催化剂；高分子材料

查看摘要 索取原文[15页]

关键词：有机材料；聚合物；高分子材料；嵌段共聚物；碳纳米管

查看摘要 索取原文[32页]

A platform technology to prepare enzyme sensitive nanomedicine (ESNM), which integrates the imaging and treatment capability, has been developed to report and cure diseases. ESNM is prepared with multiple layers of polyelectrolytes, sequentially assembled on an inert gold nanoparticle, using alternating charged polymers. Potentially the release kinetics could be controlled by varying polyelectrolytes with different properties, such as length, ionic strength and bond stability. Upon incubation with cells, the assembled ESNMs are taken up efficiently. The tight packing and layered assembly of the quenched polyelectrolytes slow subsequent intracellular degradation, and then result in a prolonged intracellular fluorescence signal and therapeutic effect for up to 3 weeks with no noticeable toxicity.

关键词：医疗服务；肽水解酶；核糖核酸；蛋白酶

查看摘要 索取原文[51页]

A summary ot three years of work is difficult to reduce to a tew sentences. We have applied Hadamard transform mass spectrometry to stop-flow kinetics and shown how this technique can complement previous stop-flow studies that rely instead on spectroscopic signatures. We have also examined hypergolic reactions. In particular, we performed electrospray ionization mass spectrometry (ESI-MS) and MS/MS fragmentation studies to determine the composition ot a previously unknown precipitate. We discovered that the precipitate consisted of melamine oligomers and polymers. However, the majority ot the effort involved an ambient ionization method that can be carried out at atmospheric pressure at room temperature-- desorption electrospray ionization (DESI). Here charged droplets are fired at some surface and the resulting splash ot smaller droplets enter a mass spectrometer. We applied this technique to show how to overcome adverse effects from salt and detergent in electrokinetic separations using a spinning disk. We also applied this technique, we believe with great success, to study reaction intermediates and to demonstrate the potential of using DESI for mass spectrometric imaging.

关键词：动力学；质谱；流量；碎裂；电离

查看摘要 索取原文[9页]

We have performed extensive experimental and theoretical studies of interfacial friction, relaxation dynamics, and thermodynamics of polymer chains tethered to points, planes, and particles. A key result from our tribology studies using lateral force microscopy (LFM) measurements of polydisperse brushes of linear and branched chains densely grafted to planar substrates is that there are exceedingly low friction coefficients for these systems. Specific project achievements include: (1) Synthesis of three-tiered lubricant films containing controlled amounts of free and pendent PDMS chains, and investigated the effect of their molecular weight and volume fraction on interfacial friction. (2.) Detailed studies of a family of hairy particles termed nanoscale organic hybrid materials (NOHMs) and demonstration of their use as lubricants.

关键词：润滑油；混合动力系统；界面摩擦；分子量；聚合物

查看摘要 索取原文[6页]

The main goal of this project has been to demonstrate the existence of novel extended solids at high pressures and temperatures and establish the viability of new functional, high energy density materials such as high- strength, insensitive CN polymers and super-oxidizing extended fluorides. There has been no major change to this original goal, and significant progresses have been made in both discoveries of the proposed functional, high-energy density candidates and developments of enabling technologies for bulk synthesis and characterization of energetic materials.

关键词：聚合物；能量性质；氟化物；高压；高分子材料

查看摘要 索取原文[30页]

The US Department of Energy (DOE) is responsible for risk reduction and cleanup of its nuclear weapons complex. DOE maintains the largest cleanup program in the world, currently spanning over a million acres in 13 states. The inventory of contaminated materials includes 90 million gallons of radioactive waste, 6.4 trillion liters of groundwater, and 40 million cubic meters of soil and debris. It is not feasible to completely restore many sites to predisposal conditions. Any contamination left in place will require monitoring, engineering controls and/or land use restrictions to protect human health and environment. Research and development efforts to date have focused on improving characterization and remediation. Yet, monitoring will result in the largest life-cycle costs and will be critical to improving performance and protection. Through an inter-disciplinary effort, DOE is addressing a need to advance monitoring approaches from sole reliance on cost- and labor-intensive point-source monitoring to integrated systems-based approaches such as flux-based approaches and the use of early indicator parameters. Key objectives include identifying current scientific, technical and implementation opportunities and challenges, prioritizing science and technology strategies to meet current needs within the DOE complex for the most challenging environments, and developing an integrated and risk-informed monitoring framework.

关键词：环境评估；监控；清洁；污染

查看摘要 索取原文[15页]

Polymer-Electrolyte-Fuel-Cells (PEFCs) are promising candidates for powering vehicles and portable devices using renewable-energy sources. The core of a PEFC is the solid electrolyte membrane that conducts protons from anode to cathode, where water is generated. The conductivity of the membrane, however, depends on the water content of the membrane, which is strongly related to the cell operating conditions. The membrane and other cell components are typically compressed to minimize various contact resistances. Moreover, the swelling of a somewhat constrained membrane in the cell due to the humidity changes generates additional compressive stresses in the membrane. These external stresses are balanced by the internal swelling pressure of the membrane and change the swelling equilibrium. It was shown using a fuel-cell setup that compression could reduce the water content of the membrane or alter the cell resistance. Nevertheless, the effect of compression on the membranes transport properties is yet to be understood, as well as its implications in the structure-functions relationships of the membrane. We previously studied, both experimentally and theoretically, how compression affects the water content of the membrane. However, more information is required the gain a fundamental understanding of the compression effects. In this talk, we present the results of our investigation on the in-situ conductivity of the membrane as a function of humidity and cell compression pressure. Moreover, to better understand the morphology of compressed membrane, small-angle X-ray-scattering (SAXS) experiments were performed. The conductivity data is then analyzed by investigating the size of the water domains of the compressed membrane determined from the SAXS measurements.

关键词：燃料电池；能源；固体电解质；聚合物

查看摘要 索取原文[7页]

 

关键词：纤维增强复合材料；聚合物；复合材料；高分子材料

查看摘要 索取原文[7页]