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Johnson, Christopher

Publications and source records attributed to Johnson, Christopher.

29 records · Page 2
All sourcesNASA NTRSDOE OSTI
DOE OSTI2019

Controlling internal degrees: general discussion

Temperature is a very important concept in ion spectroscopy and its control has seen tremendous advances in recent years. Cryogenic ion traps are now found in many experiments and serve as thermostats, reaction vessels, clustering sources and spectroscopic sample chambers. The control over internal degrees of freedom provides routes to forming ions that are relevant at cryogenic temperatures such as in the interstellar medium and to control and lock-in conformations. It also provides a condensing environment and allows weakly bound clusters to be formed, which in turn provides new routes to action spectroscopy. This session will discuss the most recent developments in cryogenic spectroscopy and the research it enables and how new theoretical methods allow the prediction of experimental spectra as a function of temperature. The main discussion topics will cover: the best cooling methods; how temperature can be used to form exotic clusters and weakly interacting systems; and the possibilities for probing conformational locking and metastable structures.

Ahmed, Musahid↗
DOE OSTI2019

Going large(r): General Discussion

With the introduction of new ion sources and advanced mass-spectrometric techniques coupled to spectroscopy, ever larger complexes are being probed. This increase in size is coupled with an increase in complexity requiring new methodologies (both experimental and theoretical) but also providing new opportunities. This session will primarily focus on the application of ion spectroscopy of non-covalent interactions in clusters and biological systems. These include solvent clusters, secondary and tertiary structure of proteins, and weakly-bound molecular clusters. Topics covered will include: structural probes for weak interactions; advances in action spectroscopy; and conformationally selective spectroscopy. A key discussion point will concern the marriage of mass-spectrometery with optical spectroscopy. The interpretation of experimental data obtained for these larger systems demands concomitant developments in theoretical methods, and the session will provide an opportunity for comparative discussions of new theoretical approaches in this field.

Ahmed, Musahid↗
DOE OSTI2019

Electrode materials for rechargeable battery

A positive electrode is disclosed for a non-aqueous electrolyte lithium rechargeable cell or battery. The electrode comprises a lithium containing material of the formula NayLixNizMn1-z-z′Mz′Od, wherein M is a metal cation, x+y > 1, 0 < z < 0.5, 0 ≤ z′<0.5, y+x+1 is less than d, and the value of d depends on the proportions and average oxidation states of the metallic elements, Li, Na, Mn, Ni, and M, if present, such that the combined positive charge of the metallic elements is balanced by the number of oxygen anions, d. The inventive material preferably has a spinel or spinel-like component in its structure. The value of y preferably is less than about 0.2, and M comprises one or more metal cations selected preferably from one or more monovalent, divalent, trivalent or tetravalent cations, such as Mg2+, Co2+, Co3+, B3+, Ga3+, Fe2+, Fe3+, Al3+, and Ti4+. The electrode material can be synthesized using an ion-exchange reaction with a lithium salt in an organic-based solvent to partially replace sodium ions of a precursor material with lithium ions.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Thermally conductive lithium ion electrodes and batteries

A thermally conductive electrochemical cell comprises a lithium ion-containing liquid electrolyte contacting a cathode and anode. The cathode and anode are in the form of electroactive sheets separated from each other by a membrane that is permeable to the electrolyte. One or more of the cathode and anode comprises two or more layers of carbon nanotubes, one of which layers includes electrochemically active nanoparticles and/or microparticles disposed therein or deposited on the nanotubes thereof. The majority of the carbon nanotubes in each of the layers are oriented generally parallel to the layers. Optionally, one or more of the layers includes an additional carbon material such as graphene, nanoparticulate diamond, microparticulate diamond, and a combination thereof.

25 ENERGY STORAGE↗
DOE OSTI2017

Enabling the high capacity of lithium-rich anti-fluorite lithium iron oxide by simultaneous anionic and cationic redox

Anionic redox reactions in cathodes of lithium-ion batteries are allowing opportunities to double or even triple the energy density. However, it is still challenging to develop a cathode, especially with Earth-abundant elements, that enables anionic redox activity for real-world applications, primarily due to limited strategies to intercept the oxygenates from further irreversible oxidation to O 2 gas. Here in this paper, we report simultaneous iron and oxygen redox activity in a Li-rich anti-fluorite Li 5 FeO 4 electrode. During the removal of the first two Li ions, the oxidation potential of O 2- is lowered to approximately 3.5 V versus Li + /Li 0 , at which potential the cationic oxidation occurs concurrently. These anionic and cationic redox reactions show high reversibility without any obvious O 2 gas release. Furthermore, this study provides an insightful guide to designing high-capacity cathodes with reversible oxygen redox activity by simply introducing oxygen ions that are exclusively coordinated by Li + .

25 ENERGY STORAGE↗
DOE OSTI2017

Implementing an Information Security Program

The threats to information security have dramatically increased with the proliferation of information systems and the internet. Chemical, biological, radiological, nuclear, and explosives (CBRNe) facilities need to address these threats in order to protect themselves from the loss of intellectual property, theft of valuable or hazardous materials, and sabotage. Project 19 of the European Union CBRN Risk Mitigation Centres of Excellence Initiative is designed to help CBRN security managers, information technology/cybersecurity managers, and other decision-makers deal with these threats through the application of cost-effective information security programs. Project 19 has developed three guidance documents that are publically available to cover information security best practices, planning for an information security management system, and implementing security controls for information security.

blended attack↗
NASA NTRS2014

The NASA High Speed ASE Project: Computational Analyses of a Low-Boom Supersonic Configuration

A summary of NASA's High Speed Aeroservoelasticity (ASE) project is provided with a focus on a low-boom supersonic configuration developed by Lockheed-Martin and referred to as the N+2 configuration. The summary includes details of the computational models developed to date including a linear finite element model (FEM), linear unsteady aerodynamic models, structured and unstructured CFD grids, and discussion of the FEM development including sizing and structural constraints applied to the N+2 configuration. Linear results obtained to date include linear mode shapes and linear flutter boundaries. In addition to the tasks associated with the N+2 configuration, a summary of the work involving the development of AeroPropulsoServoElasticity (APSE) models is also discussed.

Silva, Walter A.↗
NASA NTRS2013

Cryogenic Liquid Sample Acquisition System for Remote Space Applications

There is a need to acquire autonomously cryogenic hydrocarbon liquid sample from remote planetary locations such as the lakes of Titan for instruments such as mass spectrometers. There are several problems that had to be solved relative to collecting the right amount of cryogenic liquid sample into a warmer spacecraft, such as not allowing the sample to boil off or fractionate too early; controlling the intermediate and final pressures within carefully designed volumes; designing for various particulates and viscosities; designing to thermal, mass, and power-limited spacecraft interfaces; and reducing risk. Prior art inlets for similar instruments in spaceflight were designed primarily for atmospheric gas sampling and are not useful for this front-end application. These cryogenic liquid sample acquisition system designs for remote space applications allow for remote, autonomous, controlled sample collections of a range of challenging cryogenic sample types. The design can control the size of the sample, prevent fractionation, control pressures at various stages, and allow for various liquid sample levels. It is capable of collecting repeated samples autonomously in difficult lowtemperature conditions often found in planetary missions. It is capable of collecting samples for use by instruments from difficult sample types such as cryogenic hydrocarbon (methane, ethane, and propane) mixtures with solid particulates such as found on Titan. The design with a warm actuated valve is compatible with various spacecraft thermal and structural interfaces. The design uses controlled volumes, heaters, inlet and vent tubes, a cryogenic valve seat, inlet screens, temperature and cryogenic liquid sensors, seals, and vents to accomplish its task.

Mahaffy, Paul↗