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DOE OSTI2025

Influence of Steric and Electronic Properties of P2 Groups on Covalent Inhibitor Binding to SARS-CoV-2 Main Protease

The main protease (MPro) of SARS-CoV-2 is a critical enzyme required for viral replication, making it a prime target for antiviral drug development. Covalent inhibitors, which form a stable interaction with the catalytic C145, have demonstrated strong inhibition of MPro, but the influence of steric and electronic properties of P2 substituents, designed to engage the S2 substrate-binding subsite within the MPro active site, on inhibitor binding affinity remains underexplored. Here, in this study, we design and characterize two hybrid covalent inhibitors, BBH-3 and BBH-4, and present their X-ray crystallographic structures in complex with MPro, providing molecular insights into how their distinct P2 groups, a dichlorobenzyl moiety in BBH-3 and an adamantyl substituent in BBH-4, affect binding conformation and active site adaptability. Comparative structural analyses with previously characterized inhibitors, including BBH-2 and Mcule-5948770040, reveal how the P2 bulkiness and electronic properties influence active site dynamics, particularly through interactions with the S2 and S5 subsites. The P2 group of BBH-3 induces conformational shifts in the S2 helix and the S5 loop, while BBH-4 displaces M49, stabilizing its binding through hydrophobic interactions. Isothermal titration calorimetry further elucidates the impact of P2 modifications on inhibitor affinity, revealing a delicate balance between enthalpic and entropic contributions. The data demonstrate that BBH-3 exhibits less favorable binding, affirming that dichlorobenzyl substitution at the P2 position has a more negative impact on the affinity for MPro than bulky saturated cyclic groups. This underscores the feature that MPro active site malleability may be accompanied by a conformational strain.

SARS-CoV-2↗

DOE OSTI2023

Evolutionary consequences of nascent multicellular life cycles

A key step in the evolutionary transition to multicellularity is the origin of multicellular groups as biological individuals capable of adaptation. Comparative work, supported by theory, suggests clonal development should facilitate this transition, although this hypothesis has never been tested in a single model system. We evolved 20 replicate populations of otherwise isogenic clonally reproducing ‘snowflake’ yeast (Δace2/∆ace2) and aggregative ‘floc’ yeast (GAL1p::FLO1 /GAL1p::FLO1) with daily selection for rapid growth in liquid media, which favors faster cell division, followed by selection for rapid sedimentation, which favors larger multicellular groups. While both genotypes adapted to this regime, growing faster and having higher survival during the group-selection phase, there was a stark difference in evolutionary dynamics. Aggregative floc yeast obtained nearly all their increased fitness from faster growth, not improved group survival; indicating that selection acted primarily at the level of cells. In contrast, clonal snowflake yeast mainly benefited from higher group-dependent fitness, indicating a shift in the level of Darwinian individuality from cells to groups. Through genome sequencing and mathematical modeling, we show that the genetic bottlenecks in a clonal life cycle also drive much higher rates of genetic drift—a result with complex implications for this evolutionary transition. Our results highlight the central role that early multicellular life cycles play in the process of multicellular adaptation.

Life Sciences & Biomedicine - Other Topics↗

NASA NTRS1994

Ionospheric corrections to precise time transfer using GPS

The free electrons in the earth's ionosphere can retard the time of reception of GPS signals received at a ground station, compared to their time in free space, by many tens of nanoseconds, thus limiting the accuracy of time transfer by GPS. The amount of the ionospheric time delay is proportional to the total number of electrons encountered by the wave on its path from each GPS satellite to a receiver. This integrated number of electrons is called Total Electron Content, or TEC. Dual frequency GPS receivers designed by Allen Osborne Associates, Inc. (AOA) directly measure both the ionospheric differential group delay and the differential carrier phase advance for the two GPS frequencies and derive from this the TEC between the receiver and each GPS satellite in track. The group delay information is mainly used to provide an absolute calibration to the relative differential carrier phase, which is an extremely precise measure of relative TEC. The AOA Mini-Rogue ICS-4Z and the AOA TurboRogue ICS-4000Z receivers normally operate using the GPS P code, when available, and switch to cross-correlation signal processing when the GPS satellites are in the Anti-Spoofing (A-S) mode and the P code is encrypted. An AOA ICS-Z receiver has been operated continuously for over a year at Hanscom AFB, MA to determine the statistics of the variability of the TEC parameter using signals from up to four different directions simultaneously. The 4-channel ICS-4Z and the 8-channel ICS-4000Z, have proven capabilities to make precise, well calibrated, measurements of the ionosphere in several directions simultaneously. In addition to providing ionospheric corrections for precise time transfer via satellite, this dual frequency design allows full code and automatic codeless operation of both the differential group delay and differential carrier phase for numerous ionospheric experiments being conducted. Statistical results of the data collected from the ICS-4Z during the initial year of ionospheric time delay in the northeastern U.S., and initial results with the ICS-4000Z, will be presented.

Snow, Robert W.↗

NASA NTRS1995

Line group techniques in description of the structural phase transitions in some superconductors

The main features of the theory of line groups, and their irreducible representations are briefly discussed, as well as the most important applications of them. A new approach in the general symmetry analysis of the modulated systems is presented. It is shown, that the line group formalism could be a very effective tool in the examination of the structural phase transitions in High Temperature SUperconductors. As an example, the material YBa2Cu3O(7-x) is discussed briefly.

Meszaros, CS.↗

DOE OSTI2021

An automated procedure built on MTEX for reconstructing deformation twin hierarchies from electron backscattered diffraction datasets of heavily twinned microstructures

Here we present a set of algorithms built on the MTEX and MATLAB graph toolboxes for automatic reconstruction of deformation twin hierarchies from Electron Backscatter Diffraction (EBSD) datasets with a focus on developing methods for heavily twinned microstructures (twin fractions >0.5). The algorithms address key issues arising at large strains, mainly: missing twin relationships, grouping of heavily deformed grain fragments into families of similar orientation originating from a single initial grain, identification of parent fragments for large twin volume fractions, and classification of families having twin relationships with multiple families. To facilitate the development of these algorithms, large-grained ultra-high purity α-Ti deformed in compression along two directions is investigated. Graphs are utilized to handle non-local geometric merging and to represent relationships throughout the reconstruction process. When determining if a grain fragment is from the undeformed microstructure, the combined metrics of the fragment's orientation volume fraction in the initial texture and the directed graph centrality measure of out-closeness (the number of nodes reached in a graph from a given node) are essential. To address automation in reconstructing the sequence of twinning and relating fragments originating from a single grain in the initial microstructure, the twin family tree is formulated as a minimum spanning tree emanating from the initial grain family. A scheme constructing the distances associated with twin relationship comprising the spanning tree is developed, and a novel quasi-directional Prim spanning tree algorithm is used to determine the twin family tree. The procedure is demonstrated to significantly improve the level of automation in reconstructing twin hierarchies in heavily twinned microstructure compared to other methodologies in literature. The procedure can readily be applied to analyses of twinning in metals, as well as provide an approach for routinely extracting twin statistics at larger deformation levels than previously possible. Significantly, the procedure is demonstrated to be capable of identifying third generation twinning in α-Ti microstructures.

36 MATERIALS SCIENCE↗

DOE OSTI2020

HarDWR - Raw Water Rights Records

A dataset within the Harmonized Database of Western U.S. Water Rights (HarDWR). For a detailed description of the database, please see the meta-record v2.0. Changelog v2.0 - Switched source data from collecting records from each state independently to using the WestDAAT dataset v1.0 - Initial public release Description In order to hold a water right in the western United States, an entity, (e.g., an individual, corporation, municipality, sovereign government, or non-profit) must register a physical document with the state's water regulatory agency. State water agencies each maintain their own database containing all registered water right documents within the state, along with relevant metadata such as the point of diversion and place of use of the water. All western U.S. states have digitized their individual water rights databases, as well as geospatial data defining the areas in which water rights are managed. Each state maintains and provides their own water rights data in accordance with individual state regulations and standards. In addition, while all states make their water rights publicly available, each provides their records in unique formats, meaning that file types, field availability, and terms vary from state to state. This leads to additional challenges to managing resources which cross state lines, or conducting consistent multi-state water analyses. For the first version of HarDWR, we collected the water rights databases from 11 Western States of the United States. In order to preform regional analyses with the collected data, the raw records had to be harmonized into one single format. The Water Data Exchange (WaDE) is a program dedicated to the sharing of water-related data for the Western U.S. in a singular consistent format. Created by the Western States Water Council (WSWC) to facilitate the collection and dissemination of water data among WSWC's member states and the public, WaDE provides an important service for those interested in water resource planning and management in their focus region. Of the services which WaDE provides, the one of the most interesting is the WestDAAT dataset, which is a collection of water rights data provided by the 18 WSWC member states that have been standardized into a single format, much like we had done on a more limited scale with HarDWR v1. For this version of HarDWR we decided to use WestDAAT, specifically a snapshot created in Feburary 2024, as our water rights source data. A full explanation of the benefits gained from this switch can be found in the description of the updated Harmonized Water Rights Records v2.0, but in short it has allowed us to focus more of our efforts on answering research questions and gaining a more realistic understanding of how water rights are allocated. For more information on how the data for WestDAAT was collected, please see the WaDE data summary. Terms of Use While WaDE works directly with the state agencies to collect and standardize the water rights records, the ultimate authority for the water rights data remains the individual states. Each state, and their respective water right authorities, have made their water right records available for non-commercial reference uses. In addition, the states make no guarantees as to the completeness, accuracy, or timeliness of their respective databases, let alone the modifications which we, the authors of this paper, have made to the collected records. None of the states should be held liable for using this data outside of its intended use. As several of the states update their water rights databases daily, the information provided here is not the latest possible, and should not be used for legal purposes. WestDAAT itself has irregular updates. Additional questions about the data the source states provided should be directed to the respective state agencies (see methods.csv and organization.csv files described below). In addition, although data was presented here was not collected directly from the states, several states requested specifically worked disclaimers when sharing their data. These disclaimers are included here as an acknowledgement from where the water rights data is primarily sourced. Colorado: "The data made available here has been modified for use from its original source, which is the State of Colorado. THE STATE OF COLORADO MAKES NO REPRESENTATIONS OR WARRANTY AS TO THE COMPLETENESS, ACCURACY, TIMELINESS, OR CONTENT OF ANY DATA MADE AVAILABLE THROUGH THIS SITE. THE STATE OF COLORADO EXPRESSLY DISCLAIMS ALL WARRANTIES, WHETHER EXPRESS OR IMPLIED, INCLUDING ANY IMPLIED WARRANTIES OF MERCHANTABILITY, OR FITNESS FOR A PARTICULAR PURPOSE. The data is subject to change as modifications and updates are complete. It is understood that the information contained in the Web feed is being used at one's own risk." Montana: "The Montana State Library provides this product/service for informational purposes only. The Library did not produce it for, nor is it suitable for legal, engineering, or surveying purposes. Consumers of this information should review or consult the primary data and information sources to ascertain the viability of the information for their purposes. The Library provides these data in good faith but does not represent or warrant its accuracy, adequacy, or completeness. In no event shall the Library be liable for any incorrect results or analysis; any direct, indirect, special, or consequential damages to any party; or any lost profits arising out of or in connection with the use or the inability to use the data or the services provided. The Library makes these data and services available as a convenience to the public, and for no other purpose. The Library reserves the right to change or revise published data and/or services at any time." Oregon: "This product is for informational purposes and may not have been prepared for, or be suitable for legal, engineering, or surveying purposes. Users of this information should review or consult the primary data and information sources to ascertain the usability of the information." File Descriptions The unmodified February, 2024 WestDAAT snapshot is composed of nine files. Below is a brief description of each file, as well as how they were utilized for HarDWR. WaDEDataDictionaryTerms.xlsx: As the file's name implies, this is a data dictionary for all of the below named files. This file describes the column names for each of the following files, with the exception of citation.txt which does not have any columns. The descriptions for each file are divided by tab,with the same name as their associated file, within this document. allocationamount.csv: The "main" file of the group, it contains the water right records for each state. Of particular note, each water right is broken down into one or more water allocations. Allocations may be withdrawn from one or more locations, or even multiple allocations associated with a particular location. This is a more subtle and realistic representation of how water is used than what was available in the first version of HarDWR. For the records from some states, this can mean that multiple allocations listed under a single right will appear as rows within this file. citation.txt: A combination of contact information for WaDE personnel, disclaimer about how the data should be used, and guidelines for citing WestDAAT. methods.csv: A file describing the source and method by which WaDE collected water rights data from each state. organization.csv: A file listing the water rights authoritative agencies for each state. sites.csv: This file provides the geographic, and other descriptors, of the physical location of allocations, called 'sites'. To reiterate, it is possible for one allocation to be associated with multiple sites, as well as one site to be associated with multiple allocations. The two descriptors which we were most interested in where the site's coordinates, as well as whether the site was classified as a Point of Diversion (POD) or a Place of Use (POU). As a general rule, PODs are geographic points, while POUs are areas typically represented as property boundaries or irregularly shaped polygons. sites_pouGeometry.csv: For those allocations with a POU site, this file contains the defining points for the associated polygons. variables.csv: A file describing the units in which an allocation's water amount is reported within WestDAAT. This information is essentially a repeat of the 'AllocationFlow_CFS' and 'AllocationVolume_AF' columns within allocationamount.csv, at least for our purposes. watersources: This file describes the source of water from which each site extracts from. For our purposes, this table was used to determine whether the water came from Surface Water, Groundwater, or Unspecified Water.

Lisk, Matthew↗

NASA NTRS1982

CAD/CAM approach to improving industry productivity gathers momentum

Recent results and planning for the NASA/industry Integrated Programs for Aerospace-Vehicle Design (IPAD) program for improving productivity with CAD/CAM methods are outlined. The industrial group work is being mainly done by Boeing, and progress has been made in defining the designer work environment, developing requirements and a preliminary design for a future CAD/CAM system, and developing CAD/CAM technology. The work environment was defined by conducting a detailed study of a reference design process, and key software elements for a CAD/CAM system have been defined, specifically for interactive design or experiment control processes. Further work is proceeding on executive, data management, geometry and graphics, and general utility software, and dynamic aspects of the programs being developed are outlined

Fulton, R. E.↗

NASA NTRS1984

Cockpit resource management training

Cockpit resource management which is a multifaceted concept is outlined. The system involves the effective coordination of many resources: aircraft systems, company, air traffic control, equipment, navigational aids, documents, and manuals. The main concept, however, is group interaction. Problems which arise from lack of coordination, decision making, and lack of communication are pointed out. Implementation by the regional airline industry of cockpit resource management, designed to deal with human interactions problems in the most cost effective manner, is discussed.

Yocum, M.↗

NASA NTRS1985

Spectroscopic analysis of radiation-generated changes in tensile properties of a polyetherimide film

The effects of electron radiation on Ultem, a polyetherimide were studied for doses from 2 x 10 to the 9th power to 6 x 10 to the 9th power rad. Specimens were studied for tensile property testing and for electron paramagnetic resonance and infrared spectroscopic measurements of molecular structure. A Faraday cup design and a method for remote temperature measurement were developed. The spectroscopic data show that radiation caused dehydrogenation of methyl groups, rupture of main-chain ether linkage, and opening of imide rings, all to form radicals and indicate that the so-formed atomic hydrogen attached to phenyl radicals, but not to phenoxyl radicals, which would have formed hydroxyls. The observed decays of the radiation-generated phenoxyl, gem-dimethyl, and carbonyl radicals were interpreted as a combining of the radicals to form crosslinking. This crosslinking is the probable cause of the major reduction in the elongation of the tensile specimens after irradiation. Subsequent classical solubility tests indicate that the irradiation caused massive crosslinking.

Long, E. R., Jr.↗

NASA NTRS1989

Distant asteroids and Chiron

Knowledge of the physical properties of distant asteroids (a greater than 3.3 AU) has grown dramatically over the past five years, due to systematic compositional and lighcurve studies. Most of these objects have red, dark surfaces, and their spectra show a reddening in spectral slope with heliocentric distance, implying a change in surface composition. Trojans for which near-opposition phase curve information is available appear to show little or no opposition effect, unlike any other dark solar system objects. The lightcurve amplitudes of Trojan and Hilda asteroids imply significantly more elongated shapes for these groups than for main-belt asteroids of comparable size. These recent observations are reviewed in the context of their implications for the formationan and subsequent evolution of the distant asteroids, and their interrelations with the main belt, Chiron, and comets.

French, Linda M.↗

NASA NTRS1993

Recommendations for future research in hypersonic instrumentation

An overview of the NATO Advanced Research Workshop is presented. It describes the process followed to obtain a group consensus on the main technical recommendations for each of the five technical sessions of the Workshop and presents the general conclusions and recommendations for future research agreed upon by the workshop participants.

Ocheltree, S. L.↗

NASA NTRS1994

Basic principles of flight test instrumentation engineering, volume 1, issue 2

Volume 1 of the AG 300 series on ´Flight Test Instrumentation´ gives a general introduction to the basic principles of flight test instrumentation. The other volumes in the series provide more detailed treatments of selected topics on flight test instrumentation. Volume 1, first published in 1974, has been used extensively as an introduction for instrumentation courses and symposia, as well as being a reference work on the desk of most flight test and instrumentation engineers. It is hoped that this second edition, fully revised, will be used with as much enthusiasm as the first edition. In this edition a flight test system is considered to include both the data collection and data processing systems. In order to obtain an optimal data flow, the overall design of these two subsystems must be carefully matched; the detail development and the operation may have to be done by separate groups of specialists. The main emphasis is on the large automated instrumentation systems used for the initial flight testing of modern military and civil aircraft. This is done because there, many of the problems, which are discussed here, are more critical. It does not imply, however, that smaller systems with manual data processing are no longer used. In general, the systems should be designed to provide the required results at the lowest possible cost. For many tests which require only a few parameters, relatively simple systems are justified, especially if no complex equipment is available to the user. Although many of the aspects discussed in this volume apply to both small and large systems, aspects of the smaller systems are mentioned only when they are of special interest. The volume has been divided into three main parts. Part 1 defines the main starting points for the design of a flight test instrumentation system, as seen from the points of view of the flight test engineer and the instrumentation engineer. In Part 2 the discussion is concentrated on those aspects which apply to each individual measuring channel, and in Part 3 the main emphasis is on the integration of the individual data channels into one data collection system and on those aspects of the data processing which apply to the complete system.

channels (data transmission)↗

NASA NTRS2004

Thin Film Solar Cells: Organic, Inorganic and Hybrid

Thin film solar cells are an important developing resource for hundreds of applications including space travel. In addition to being more cost effective than traditional single crystal silicon cells, thin film multi-crystaline cells are plastic and light weight. The plasticity of the cells allows for whole solar panels to be rolled out from reams. Organic layers are being investigated in order to increase the efficiency of the cells to create an organic / inorganic hybrid cell. The main focus of the group is a thin film inorganic cell made with the absorber CuInS2. So far the group has been successful in creating the layer from a single-source precursor. They also use a unique method of film deposition called chemical vapor deposition for this. The general makeup of the cell is a molybdenum back contact with the CuInS2 layer, then CdS, ZnO and aluminum top contacts. While working cells have been produced, the efficiency so far has been low. Along with quantum dot fabrication the side project of this that is currently being studied is adding a polymer layer to increase efficiency. The polymer that we are using is P3OT (Poly(3-octylthiopene-2,5-diyll), retroregular). Before (and if) it is added to the cell, it must be understood in itself. To do this simple diodes are being constructed to begin to look at its behavior. The P3OT is spin coated onto indium tin oxide and silver or aluminum contacts are added. This method is being studied in order to find the optimal thickness of the layer as well as other important considerations that may later affect the composition of the finished solar cell. Because the sun is the most abundant renewable, energy source that we have, it is important to learn how to harness that energy and begin to move away from our other depleted non-renewable energy sources. While traditional silicon cells currently create electricity at relatively high efficiencies, they have drawbacks such as weight and rigidness that make them unattractive especially for space applications. Thin film photovoltaics have the potential to alleviate these problems and create a cheap and efficient way to harness the power of the sun.

Dankovich, John↗

NASA NTRSDate not supplied

Identifying Information Needs and Tools to Support Interactions between Upper Class E Traffic Management (ETM) Operations and the Air Traffic System (ATS)

With the introduction of high-altitude long endurance (HALE) vehicles and balloons designed to operate above 60,000 feet, the frequency and duration of operations in Upper Class E airspace are expected to increase. In response to the need for scalable traffic management for these diverse operations at higher altitudes, the FAA introduced the Upper Class E Traffic Management (ETM) concept. Like the successful demonstration of Uncrewed Aircraft System (UAS) Traffic Management (UTM), the ETM concept is also designed as a community-based, industry-driven cooperative approach to traffic management. As these vehicles and balloons ascend to/descend from ETM Cooperative Areas in Upper Class E, they will transit through Class A controlled airspace where they will interact with various entities of the conventional Air Traffic System (ATS) (e.g., Air Traffic Control (ATC)). This work explores tools that will help support ETM-ATS interactions for users throughout the ATS, as well as ETM Operators. An information needs analysis using ETM-ATS interaction use cases, revealed that the needed functionalities generally grouped themselves into two main themes, the visualization of flights and airspace designations, and digital communication capabilities across various human users. In this paper, we describe two envisioned tools, 1) an Integrated Visualization Tool to display flight information and airspace designations, and 2) an Integrated Digital Communication Tool to facilitate two-way information exchange between users about vehicle position information, the coordination of airspace approvals, and notifications. The tools we describe create an integrated visual representation of vehicles and airspace designations with a set of communication capabilities to consolidate information into a single display interface. These tools may be used to guide the development of prototype tools for demonstrations at the National Aeronautics and Space Administration (NASA) Ames Research Center to further explore ETM-ATS interactions within the ETM concept.

Upper Class E Traffic Management (ETM)↗

NASA NTRSDate not supplied

Identifying Information Needs and Tools to Support Interactions between Upper Class E Traffic Management (ETM) Operations and the Air Traffic System (ATS)

Upper Class E Traffic Management (ETM)↗

DOE OSTI2023

Heliostat Consortium: Update on Resource, Training, and Education Development and Women+ in Concentrating Solar

One of the major barriers to Concentrating Solar Power (CSP) industry growth in the U.S. is the lack of accessibility of expert knowledge, a lack of a stable workforce pipeline, and little public awareness of the technology area. Improved Resource, Training, and Education (RTE) is needed to address these gaps, to draw workers into the field from diverse technology areas and backgrounds, and to reduce the learning curves of newcomers into the industry. As part of the RTE topic under the NREL-led Heliostat Consortium (HelioCon), a public online resource database has been created to support information sharing across the heliostat and CSP community. Here, information will be presented on the existing and planned database resources, including introductory information about CSP and heliostats, a reference library of texts and publications, educational videos, a CSP power tower plant database and case studies, a contact list of component suppliers and developers, and a list of available software/metrology tools. Women+ in Concentrating Solar is a newly created organization to promote the education, professional development, and advancement of underrepresented genders in the Concentrating Solar Power (CSP) community in a way that includes diverse backgrounds, attitudes, and perspectives. The main objectives of the groups are to provide the following opportunities for underrepresented genders: 1) organize events to provide networking opportunities and community building, 2) boost partnerships and scientific collaboration, 3) create resources to facilitate knowledge and experience sharing, 4) provide mentorship programs to support those new to the industry, 5) bring visibility to underrepresented genders and attract more to the field, and 6) promote Diversity, Equity, and Inclusion (DEI) and engage minorities and underrepresented groups. Initial activities being pursued by the group include creating an expert database to support event organizers in recruiting speakers with representation of all gender identities, hosting online networking and webinar events, organizing conference events including seminars and networking/social events, and establishing a mentorship program to connect members in the CSP community across the globe. The group is open to all genders and has grown to over 60 members in its first few months.

concentrating solar↗

DOE OSTI2022

Synthesis and Exploratory Catalysis of 3d Metals: Atom and Group-Transfer Reactions and the Activation and Functionalization of Small Molecules Including Greenhouse Gases

Determining ways to convert natural gas, with zero emissions, and to more value-added materials such as olefins is one of the main goals in my research group. Over this funding period, we explored the chemistry of early-transition metals with metal-nitrogen multiple bonds, specifically titanium and zirconium nitrides, and explored their redox properties, basicity and reactivity with small molecules including greenhouses gases such as carbon dioxide. Some of these work serve as inspiration for the chemistry of important materials such as uranium nitride along with its unprecedented basicity and ability to activate C-H bonds. Using robust chelating templates we also examined rare examples of trivalent group 4 transition metal ions, and studied these spectroscopically. Using early transition metal ions we also explored synthetic routes to new phosphide based products using the phosphaethynolate salt. In addition, we also explored the chemistry of ferrous systems, and redox active ligand that can allow us to reversibly break and make C-S as well as N-N bonds, activate dinitrogen forming unusual MNNM topologies. Our final component describes how we activate methane and dehydrocouple if with a carbene source to form ethylene. Using this information, we also discovered a simple to make iridium catalyst that activate and functionalize methane with 9:1 selectivity for mono-functionalization. We have established a pathway that leads to poisoning of the catalyst and have found optimal conditions for higher selectivity and with over 170 Turnovers.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

NASA NTRS1998

What Were the Major Factors That Controlled Mineralogical Similarities and Differences of Basaltic, Lherzolitic and Clinopyroxentic Martian Meteorites Within Each Group

Twelve martian meteorites that have been re- covered so far are classified into five groups (basalt, lherzolite, clinopyroxenite, dunite, and orthopyroxenite) mainly from petrology and chemistry. Among them, the dunite and orthopyroxenite groups consist of only one meteorite each (dunite: Chassigny, orthopyroxenite: ALH 84001). The basalt group is the largest group and consists of four meteorites (Shergotty, Zagani, EETA 79001, and QUE 94201). The lherzolitic and clinopyroxenitic groups include three meteorites each (Lherzolite: ALH 77005, LEW 88516, and Y793605, clinopyroxenite: Nakhla, Governador Valadares, and Lafayette). These meteorites within each group are generally similar to the others, but none of them is paired with the others. In this abstract, we discuss the major factors that controlled mineralogical similarities and differences of basaltic, lherzolitic, and clinopyroxenitic meteorites within each group. This may help in understanding their petrogenesis and original locations on Mars in general.

Mikouchi, T.↗