ALBERT

Description: Lithium-oxygen (Li-O2) batteries have the highest theoretical energy density of all the Li-based energy storage systems, but many challenges prevent them from practical use. A major obstacle is the sluggish performance of the air cathode, where both oxygen reduction (discharge) and oxygen evolution (charge) reactions occur. Recently there have been significant advances in the development of graphene-based air cathode materials with a large surface area and high catalytic activity for both oxygen reduction and evolution reactions. However, most studies reported so far have examined air cathodes with a limited areal mass loading rarely exceeding 1 mg/cm2. Despite the high gravimetric capacity values achieved, therefore, the actual (areal) capacities of those batteries were far from sufficient for practical applications. Here, we present the fabrication, performance, and mechanistic investigations of high mass loading (up to 10 mg/cm2) graphene-based air electrodes for high-performance Li-O2 batteries. Such air electrodes could be easily prepared within minutes under solvent-free and binder-free conditions by compression molding holey graphene because of the unique dry compressibility of this graphene structural derivative with in-plane holes. High mass loading Li-O2 batteries prepared in this manner exhibited excellent gravimetric capacity and thus ultrahigh areal capacity (as high as ~40 mAh/cm2). The batteries were also cycled at a high curtailing areal capacity (2 mAh/cm2), with ultrathick cathodes showing a better stability during cycling than thinner ones. Detailed postmortem analyses of the electrodes clearly revealed the battery failure mechanisms under both primary and secondary modes, which were the oxygen diffusion blockage and the catalytic site deactivation, respectively. The results strongly suggest that the dry-pressed holey graphene electrodes are a highly viable architectural platform for high capacity, high performance air cathodes in Li-O2 batteries of practical significance.

Description: Our growing awareness of the microbial world’s importance and diversity contrasts starkly with our limited understanding of its fundamental structure. Despite recent advances in DNA sequencing, a lack of standardized protocols and common analytical frameworks impedes comparisons among studies, hindering the development of global inferences about microbial life on Earth. Here we present a meta-analysis of microbial community samples collected by hundreds of researchers for the Earth Microbiome Project. Coordinated protocols and new analytical methods, particularly the use of exact sequences instead of clustered operational taxonomic units, enable bacterial and archaeal ribosomal RNA gene sequences to be followed across multiple studies and allow us to explore patterns of diversity at an unprecedented scale. The result is both a reference database giving global context to DNA sequence data and a framework for incorporating data from future studies, fostering increasingly complete characterization of Earth’s microbial diversity.

Description: Calculations are performed to determine the dynamic effects of mechanical power transmission from the nacelle of a horizontal axis wind machine to the ground or to an intermediate level. It is found that resonances are likely at 2 or 4/REV, but they occur at low power only, and seem easily correctable. Large reductions are found in the harmonic torque inputs to the generator at powers near rated.

Description: The National Aeronautics and Aerospace Administration (NASA) relies in the security and protection of the information and information systems to know the devices that are connected to the Agency networks whether these are business, mission, research, or engineering devices. The Agency uses different Information Technology resources in order to do this process automatically, however, there are some devices that need to be reported manually. As a result of this, every month the Agency distributes among its Information System Owners (ISOs) the Manual Asset Inventory, a document that consists of a Microsoft Excel spreadsheet with twenty field descriptions cells that has to be filled out by the ISO of every Security Plan in the Center [fifty three in total] and uploaded into the IT Security Enterprise Data Warehouse (ITSEC-EDW).

Description: Context. The nearby and young M star AU Mic is surrounded by a debris disk in which we previously identified a series of large-scale arch-like structures that have never been seen before in any other debris disk and that move outward at high velocities. Aims. We initiated a monitoring program with the following objectives: (1) track the location of the structures and better constrain their projected speeds, (2) search for new features emerging closer in, and ultimately (3) understand the mechanism responsible for the motion and production of the disk features. Methods. AU Mic was observed at 11 different epochs between August 2014 and October 2017 with the IR camera and spectrograph of SPHERE. These high-contrast imaging data were processed with a variety of angular, spectral, and polarimetric differential imaging techniques to reveal the faintest structures in the disk. We measured the projected separations of the features in a systematic way for all epochs. We also applied the very same measurements to older observations from the Hubble Space Telescope (HST) with the visible cameras STIS and ACS. Results. The main outcomes of this work are (1) the recovery of the five southeastern broad arch-like structures we identified in our first study, and confirmation of their fast motion (projected speed in the range 412 km/s); (2) the confirmation that the very first structures observed in 2004 with ACS are indeed connected to those observed later with STIS and now SPHERE; (3) the discovery of two new very compact structures at the northwest side of the disk (at 0.40 and 0.55 in May 2015) that move to the southeast at low speed; and (4) the identification of a new arch-like structure that might be emerging at the southeast side at about 0.4 from the star (as of May 2016). Conclusions. Although the exquisite sensitivity of SPHERE allows one to follow the evolution not only of the projected separation, but also of the specific morphology of each individual feature, it remains difficult to distinguish between possible dynamical scenarios that may explain the observations. Understanding the exact origin of these features, the way they are generated, and their evolution over time is certainly a significant challenge in the context of planetary system formation around M stars.

Description: This report covers the entire effort of GE Global Research's NASA Prime Contract NNC15CA02C "Evaluation of Low Noise Integration Concepts and Propulsion Technologies for Future Supersonic Civil Transports". GE Global Research was supported by GE Aviation and Lockheed Martin in exploring the potential of wing shielding, flight path optimization, and jet noise technology to target aggressive community noise levels of 10 EPNdB lower than Chapter 14 for a future (mid-term) commercial supersonic transport aircraft.

Description: The linear rocket engine is shown to be a viable candidate propulsion system for post-Space Shuttle single-stage-to-orbit systems. The linear engine system has been developed and fired demonstrating high performance and long life with firing durations exceeding 500 seconds. The application of the split or dual combustor to the linear engine permits the uses of two different propellant combinations in a single engine system. The split combustor possesses the advantages of the two position extendible bell nozzle in a fixed nozzle configuration. Engine power cycles and applications to typical vehicles are discussed.

Description: We requested and have been approved for 5 Hayabusa samples in order definitively establish the degree of shock experienced by the regolith of asteroid Itokawa, and to devise a bridge between shock determinations by standard light optical petrography, crystal structures as determined by synchrotron X-ray diffraction (SXRD), and degree of crystallinity as determined by electron back-scattered diffraction (EBSD) [1,2]. As of the writing of this abstract we are awaiting the approved samples. We propose measurements of astromaterial crystal structures and regolith processes. The proposed research work will improve our understanding of how small, primitive solar system bodies formed and evolved, and improve understanding of the processes that determine the history and future of habitability of environments on other solar system bodies. The results of the proposed research will directly enrich the ongoing asteroid and comet exploration missions by NASA, JAXA and ESA, and broaden our understanding of the origin and evolution of small bodies in the early solar system, and elucidate the nature of asteroid and comet regolith.

Description: No abstract available