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All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on CuH4(ClO)2 by Materials Project

CuH4(OCl)2 crystallizes in the orthorhombic Pmna space group. The structure is zero-dimensional and consists of two 10125-13-0 molecules. Cu2+ is bonded in a distorted square co-planar geometry to two equivalent O2- and two equivalent Cl1- atoms. Both Cu–O bond lengths are 1.94 Å. Both Cu–Cl bond lengths are 2.29 Å. H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. O2- is bonded in a distorted trigonal planar geometry to one Cu2+ and two equivalent H1+ atoms. Cl1- is bonded in a distorted single-bond geometry to one Cu2+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Distinct Bimetallic Cooperativity Among Water Reduction Catalysts Containing [Co III Co III ], [Ni II Ni II ], and [Zn II Zn II ] Cores

We report three binuclear species [LCo III 2 (μ-Pz) 2 ](ClO 4 ) 3 (1), [LNi II 2 (CH 3 OH) 2 Cl 2 ]ClO 4 (2), and [LZn II 2 Cl 2 ]PF 6 (3) supported by the deprotonated form of the ligand 2,6-bis[bis(2-pyridylmethyl) amino-methyl]-4-methylphenol were synthesized, structurally characterized as solids and in solution, and had their electrochemical and spectroscopic behavior established. Species 1–3 had their water reduction ability studied aiming to interrogate the possible cooperative catalytic activity between two neighboring metal centers. Species 1 and 2 reduced H 2 O to H 2 effectively at an applied potential of -1.6 V Ag/AgCl , yielding turnover numbers of 2,820 and 2,290, respectively, after 30 minutes. Species 3 lacked activity and was used as a negative control to eliminate the possibility of ligand-based catalysis. Pre- and post-catalytic data gave evidence of the molecular nature of the process within the timeframe of the experiments. Species 1 showed structural, rather than electronic cooperativity, while species 2 displayed no obvious cooperativity. DFT methods complemented the experimental results determining plausible mechanisms.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2020

Materials Data on Ni(ClO)2 by Materials Project

NiCl2O2 crystallizes in the monoclinic C2/m space group. The structure is one-dimensional and consists of four hydrogen peroxide molecules and two NiCl2 ribbons oriented in the (0, 1, 0) direction. In each NiCl2 ribbon, Ni is bonded in a square co-planar geometry to four Cl atoms. All Ni–Cl bond lengths are 2.33 Å. There are two inequivalent Cl sites. In the first Cl site, Cl is bonded in an L-shaped geometry to two equivalent Ni atoms. In the second Cl site, Cl is bonded in an L-shaped geometry to two equivalent Ni atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Sr2Cu(ClO)2 by Materials Project

Sr2CuO2Cl2 crystallizes in the tetragonal P4/mmm space group. The structure is three-dimensional. Sr2+ is bonded to four O2- and two equivalent Cl1- atoms to form a mixture of edge and corner-sharing SrCl2O4 octahedra. The corner-sharing octahedral tilt angles are 0°. All Sr–O bond lengths are 2.47 Å. Both Sr–Cl bond lengths are 3.06 Å. Cu2+ is bonded in a square co-planar geometry to four Cl1- atoms. All Cu–Cl bond lengths are 2.47 Å. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a square co-planar geometry to four equivalent Sr2+ atoms. In the second O2- site, O2- is bonded in a square co-planar geometry to four equivalent Sr2+ atoms. There are two inequivalent Cl1- sites. In the first Cl1- site, Cl1- is bonded in a square co-planar geometry to two equivalent Sr2+ and two equivalent Cu2+ atoms. In the second Cl1- site, Cl1- is bonded in a square co-planar geometry to two equivalent Sr2+ and two equivalent Cu2+ atoms. Both Cl–Sr bond lengths are 3.06 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Structural Tuning of Self‐Conductive Polymer as Gas Diffusion Layer for Electrocatalytic Reactions at High Current

Electrocatalytic conversions offer a promising route for sustainable chemical production using renewable energy. Gas diffusion layers (GDLs) enable selective product formation at high current densities but suffer from electrolyte flooding, and polytetrafluoroethylene (PTFE)-based GDLs typically require metal conductive layers, which constrain catalyst development. A recently developed GDL configuration, electropolymerized poly(3,4-ethylenedioxythiophene) (PEDOT)-coated PTFE, demonstrates notable flooding resistance, but suffers from gas diffusion limitations at elevated currents due to limited gas diffusion through the PEDOT layer. Here, different dopants in PEDOT are exploited to modify the physical properties and enhance gas transport. ClO 4 − -doped PEDOT exhibits superior performance due to optimized physical structure, leading to increased gas permeance and faradaic efficiency (FE) for CO production during electrocatalytic CO 2 reduction. Further optimization of coverage and thickness achieved by adjusting charge density led to an optimal configuration at 33 mC cm −2 . This GDL supports various metal electrocatalysts and demonstrates FE CO of > 90% for over 150 h at −200 mA cm −2 using a commercial silver electrocatalyst. This work highlights the importance of GDL engineering in enhancing performance and durability for long-term electrocatalytic processes.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2020

Materials Data on Ca2Cu(ClO)2 by Materials Project

Ca2CuO2Cl2 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Ca2+ is bonded in a 9-coordinate geometry to four equivalent O2- and five equivalent Cl1- atoms. All Ca–O bond lengths are 2.51 Å. There are four shorter (3.00 Å) and one longer (3.27 Å) Ca–Cl bond lengths. Cu2+ is bonded in a distorted square co-planar geometry to four equivalent O2- and two equivalent Cl1- atoms. All Cu–O bond lengths are 1.94 Å. Both Cu–Cl bond lengths are 2.79 Å. O2- is bonded to four equivalent Ca2+ and two equivalent Cu2+ atoms to form a mixture of corner, edge, and face-sharing OCa4Cu2 octahedra. The corner-sharing octahedral tilt angles are 0°. Cl1- is bonded in a 6-coordinate geometry to five equivalent Ca2+ and one Cu2+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Sr2Cu(ClO)2 by Materials Project

Sr2CuO2Cl2 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Sr2+ is bonded in a 9-coordinate geometry to four equivalent O2- and five equivalent Cl1- atoms. All Sr–O bond lengths are 2.63 Å. There are four shorter (3.07 Å) and one longer (3.39 Å) Sr–Cl bond lengths. Cu2+ is bonded in a distorted square co-planar geometry to four equivalent O2- and two equivalent Cl1- atoms. All Cu–O bond lengths are 1.99 Å. Both Cu–Cl bond lengths are 2.93 Å. O2- is bonded to four equivalent Sr2+ and two equivalent Cu2+ atoms to form a mixture of corner, edge, and face-sharing OSr4Cu2 octahedra. The corner-sharing octahedral tilt angles are 0°. Cl1- is bonded in a 6-coordinate geometry to five equivalent Sr2+ and one Cu2+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on ZnC2N6(ClO)2 by Materials Project

ZnC2N6(OCl)2 is alpha structured and crystallizes in the monoclinic P2_1/c space group. The structure is zero-dimensional and consists of two ZnC2N6(OCl)2 clusters. Zn2+ is bonded in a distorted square co-planar geometry to two equivalent N+0.67-, two equivalent O2-, and two equivalent Cl1- atoms. Both Zn–N bond lengths are 2.88 Å. Both Zn–O bond lengths are 2.43 Å. Both Zn–Cl bond lengths are 2.16 Å. C4+ is bonded in a linear geometry to one N+0.67- and one O2- atom. The C–N bond length is 1.22 Å. The C–O bond length is 1.20 Å. There are three inequivalent N+0.67- sites. In the first N+0.67- site, N+0.67- is bonded in a single-bond geometry to one N+0.67- atom. The N–N bond length is 1.11 Å. In the second N+0.67- site, N+0.67- is bonded in a distorted bent 150 degrees geometry to one Zn2+ and one N+0.67- atom. In the third N+0.67- site, N+0.67- is bonded in a single-bond geometry to one C4+ atom. O2- is bonded in a 2-coordinate geometry to one Zn2+ and one C4+ atom. Cl1- is bonded in a single-bond geometry to one Zn2+ atom.

36 MATERIALS SCIENCE↗
NASA NTRS1988

Chemistry of the CO dimer at low temperatures

Researchers conducted a series of experiments on the chlorine-catalyzed photodecomposition of O sub 3 both in the gas and in inert solvents such as CF sub 4 and CO sub 2 in the temperature range about 190 to 225 K. The liquid medium was chosen in order to minimize possible surface loss of long-lived ClO dimer, and to aid in the stabilization of transient excited intermediates. The mechanism of dimer formation was as follows: (1) Cl sub 2 + hv yields Cl + Cl; (2) Cl + O sub 3 yields ClO + O sub 2; (3) ClO + ClO yields Cl sub 2 O sub 2. The experiments were done in cooled low temperature cells, with irradiation from an Osram high pressure mercury arc, filtered to remove radiation below 325 nm. Spectral analysis was by means of a Cary Model 2200 UV spectrometer. The principal objectives were: (1) to determine the lifetime of the dimer as a function of temperature; (2) to observe spectral changes in the mixtures which could be attributed to dimer or related products; and (3) to observe chemical or photochemical reactions of the dimer.

Demore, W. B.↗
DOE OSTI2020

Materials Data on CuH8C4N8(ClO)2 by Materials Project

CuC4H8(N4O)2Cl2 is Cyanogen Chloride-derived structured and crystallizes in the triclinic P-1 space group. The structure is zero-dimensional and consists of two hydrochloric acid molecules and one CuC4H8(N4O)2 cluster. In the CuC4H8(N4O)2 cluster, Cu2+ is bonded in a square co-planar geometry to two equivalent N+2.50- and two equivalent O2- atoms. Both Cu–N bond lengths are 1.84 Å. Both Cu–O bond lengths are 1.80 Å. There are two inequivalent C4+ sites. In the first C4+ site, C4+ is bonded in a linear geometry to two N+2.50- atoms. There is one shorter (1.18 Å) and one longer (1.27 Å) C–N bond length. In the second C4+ site, C4+ is bonded in a trigonal planar geometry to three N+2.50- atoms. There are a spread of C–N bond distances ranging from 1.33–1.36 Å. There are four inequivalent N+2.50- sites. In the first N+2.50- site, N+2.50- is bonded in a distorted bent 150 degrees geometry to one Cu2+ and one C4+ atom. In the second N+2.50- site, N+2.50- is bonded in a bent 120 degrees geometry to two C4+ atoms. In the third N+2.50- site, N+2.50- is bonded in a trigonal planar geometry to one C4+ and two H1+ atoms. Both N–H bond lengths are 1.02 Å. In the fourth N+2.50- site, N+2.50- is bonded in a trigonal planar geometry to one C4+ and two H1+ atoms. Both N–H bond lengths are 1.03 Å. There are four inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a single-bond geometry to one N+2.50- atom. In the second H1+ site, H1+ is bonded in a single-bond geometry to one N+2.50- atom. In the third H1+ site, H1+ is bonded in a single-bond geometry to one N+2.50- atom. In the fourth H1+ site, H1+ is bonded in a single-bond geometry to one N+2.50- atom. O2- is bonded in a single-bond geometry to one Cu2+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on NiSn(ClO)6 by Materials Project

NiSn(OCl3)2(O2)2 crystallizes in the triclinic P-1 space group. The structure is one-dimensional and consists of two hydrogen peroxide molecules and one NiSn(OCl3)2 ribbon oriented in the (1, 0, 0) direction. In the NiSn(OCl3)2 ribbon, Ni is bonded in a square co-planar geometry to two equivalent O and two equivalent Cl atoms. Both Ni–O bond lengths are 1.97 Å. Both Ni–Cl bond lengths are 2.35 Å. Sn is bonded in an octahedral geometry to two equivalent O and four Cl atoms. Both Sn–O bond lengths are 2.18 Å. There are two shorter (2.38 Å) and two longer (2.54 Å) Sn–Cl bond lengths. O is bonded in a trigonal planar geometry to one Ni, one Sn, and one Cl atom. The O–Cl bond length is 1.69 Å. There are three inequivalent Cl sites. In the first Cl site, Cl is bonded in an L-shaped geometry to one Ni and one Sn atom. In the second Cl site, Cl is bonded in a single-bond geometry to one O atom. In the third Cl site, Cl is bonded in a single-bond geometry to one Sn atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on BaHg2(ClO)2 by Materials Project

BaHg2(OCl)2 crystallizes in the tetragonal P4/mbm space group. The structure is three-dimensional. Ba2+ is bonded in a 9-coordinate geometry to four equivalent O2- and five Cl1- atoms. All Ba–O bond lengths are 2.80 Å. There are a spread of Ba–Cl bond distances ranging from 3.20–3.77 Å. Hg2+ is bonded in a distorted linear geometry to two equivalent O2- and four Cl1- atoms. There are one shorter (2.10 Å) and one longer (2.11 Å) Hg–O bond lengths. There are two shorter (3.10 Å) and two longer (3.17 Å) Hg–Cl bond lengths. O2- is bonded to two equivalent Ba2+ and two equivalent Hg2+ atoms to form a mixture of distorted edge and corner-sharing OBa2Hg2 tetrahedra. There are three inequivalent Cl1- sites. In the first Cl1- site, Cl1- is bonded in a distorted square co-planar geometry to four equivalent Ba2+ atoms. In the second Cl1- site, Cl1- is bonded in a 5-coordinate geometry to three equivalent Ba2+ and four equivalent Hg2+ atoms. In the third Cl1- site, Cl1- is bonded in a body-centered cubic geometry to eight equivalent Hg2+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CuH18C4N10(ClO)2 by Materials Project

(CuH14(C2N5)2)2(H2O)2(H2OCl)2Cl2 crystallizes in the triclinic P-1 space group. The structure is zero-dimensional and consists of two hydrochloric acid molecules; two hydrochloric acid, monohydrate molecules; two water molecules; and two CuH14(C2N5)2 clusters. In each CuH14(C2N5)2 cluster, Cu2+ is bonded in a square co-planar geometry to four N3- atoms. There is one shorter (1.95 Å) and three longer (1.96 Å) Cu–N bond length. There are four inequivalent C4+ sites. In the first C4+ site, C4+ is bonded in a trigonal planar geometry to three N3- atoms. There are a spread of C–N bond distances ranging from 1.31–1.38 Å. In the second C4+ site, C4+ is bonded in a trigonal planar geometry to three N3- atoms. There are a spread of C–N bond distances ranging from 1.31–1.37 Å. In the third C4+ site, C4+ is bonded in a trigonal planar geometry to three N3- atoms. There are a spread of C–N bond distances ranging from 1.31–1.38 Å. In the fourth C4+ site, C4+ is bonded in a trigonal planar geometry to three N3- atoms. There are a spread of C–N bond distances ranging from 1.31–1.37 Å. There are ten inequivalent N3- sites. In the first N3- site, N3- is bonded in a distorted trigonal planar geometry to one Cu2+, one C4+, and one H1+ atom. The N–H bond length is 1.02 Å. In the second N3- site, N3- is bonded in a trigonal planar geometry to one C4+ and two H1+ atoms. There is one shorter (1.01 Å) and one longer (1.02 Å) N–H bond length. In the third N3- site, N3- is bonded in a trigonal planar geometry to two C4+ and one H1+ atom. The N–H bond length is 1.05 Å. In the fourth N3- site, N3- is bonded in a trigonal planar geometry to one C4+ and two H1+ atoms. There is one shorter (1.01 Å) and one longer (1.02 Å) N–H bond length. In the fifth N3- site, N3- is bonded in a distorted trigonal planar geometry to one Cu2+, one C4+, and one H1+ atom. The N–H bond length is 1.02 Å. In the sixth N3- site, N3- is bonded in a distorted trigonal planar geometry to one Cu2+, one C4+, and one H1+ atom. The N–H bond length is 1.03 Å. In the seventh N3- site, N3- is bonded in a trigonal planar geometry to one C4+ and two H1+ atoms. Both N–H bond lengths are 1.02 Å. In the eighth N3- site, N3- is bonded in a trigonal planar geometry to two C4+ and one H1+ atom. The N–H bond length is 1.04 Å. In the ninth N3- site, N3- is bonded in a distorted trigonal planar geometry to one C4+ and two H1+ atoms. Both N–H bond lengths are 1.02 Å. In the tenth N3- site, N3- is bonded in a distorted trigonal planar geometry to one Cu2+, one C4+, and one H1+ atom. The N–H bond length is 1.03 Å. There are fourteen inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a single-bond geometry to one N3- atom. In the second H1+ site, H1+ is bonded in a single-bond geometry to one N3- atom. In the third H1+ site, H1+ is bonded in a single-bond geometry to one N3- atom. In the fourth H1+ site, H1+ is bonded in a single-bond geometry to one N3- atom. In the fifth H1+ site, H1+ is bonded in a single-bond geometry to one N3- atom. In the sixth H1+ site, H1+ is bonded in a single-bond geometry to one N3- atom. In the seventh H1+ site, H1+ is bonded in a single-bond geometry to one N3- atom. In the eighth H1+ site, H1+ is bonded in a single-bond geometry to one N3- atom. In the ninth H1+ site, H1+ is bonded in a single-bond geometry to one N3- atom. In the tenth H1+ site, H1+ is bonded in a single-bond geometry to one N3- atom. In the eleventh H1+ site, H1+ is bonded in a single-bond geometry to one N3- atom. In the twelfth H1+ site, H1+ is bonded in a single-bond geometry to one N3- atom. In the thirteenth H1+ site, H1+ is bonded in a single-bond geometry to one N3- atom. In the fourteenth H1+ site, H1+ is bonded in a single-bond geometry to one N3- atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CoC12N8(ClO5)2 by Materials Project

CoO4(C5N4)2(CO2)2(ClO)2 crystallizes in the triclinic P-1 space group. The structure is zero-dimensional and consists of two formic acid molecules, two C5N4 clusters, one ClO cluster, and one CoO4 cluster. In each C5N4 cluster, there are five inequivalent C+3.67+ sites. In the first C+3.67+ site, C+3.67+ is bonded in a single-bond geometry to one N3- atom. The C–N bond length is 1.30 Å. In the second C+3.67+ site, C+3.67+ is bonded in a bent 120 degrees geometry to two N3- atoms. There is one shorter (1.32 Å) and one longer (1.42 Å) C–N bond length. In the third C+3.67+ site, C+3.67+ is bonded in a bent 120 degrees geometry to two N3- atoms. There is one shorter (1.39 Å) and one longer (1.58 Å) C–N bond length. In the fourth C+3.67+ site, C+3.67+ is bonded in a bent 120 degrees geometry to two N3- atoms. There is one shorter (1.32 Å) and one longer (1.40 Å) C–N bond length. In the fifth C+3.67+ site, C+3.67+ is bonded in a bent 120 degrees geometry to two N3- atoms. There is one shorter (1.35 Å) and one longer (1.38 Å) C–N bond length. There are four inequivalent N3- sites. In the first N3- site, N3- is bonded in a bent 120 degrees geometry to two C+3.67+ atoms. In the second N3- site, N3- is bonded in a bent 120 degrees geometry to two C+3.67+ atoms. In the third N3- site, N3- is bonded in a 3-coordinate geometry to three C+3.67+ atoms. In the fourth N3- site, N3- is bonded in a water-like geometry to two C+3.67+ atoms. In the ClO cluster, O2- is bonded in a distorted L-shaped geometry to two equivalent Cl1- atoms. There is one shorter (1.56 Å) and one longer (2.33 Å) O–Cl bond length. Cl1- is bonded in a 2-coordinate geometry to two equivalent O2- atoms. In the CoO4 cluster, Co2+ is bonded in a square co-planar geometry to four O2- atoms. There is two shorter (1.64 Å) and two longer (1.88 Å) Co–O bond length. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a single-bond geometry to one Co2+ atom. In the second O2- site, O2- is bonded in a distorted single-bond geometry to one Co2+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on TeC4S4N8(ClO)2 by Materials Project

C4TeS2(N4Cl)2(SO)2 crystallizes in the monoclinic P2_1/c space group. The structure is zero-dimensional and consists of four sulfur monoxide molecules and two C4TeS2(N4Cl)2 clusters. In each C4TeS2(N4Cl)2 cluster, there are two inequivalent C4+ sites. In the first C4+ site, C4+ is bonded in a 3-coordinate geometry to two N1- atoms. There is one shorter (1.31 Å) and one longer (1.32 Å) C–N bond length. In the second C4+ site, C4+ is bonded in a linear geometry to two N1- atoms. There is one shorter (1.18 Å) and one longer (1.31 Å) C–N bond length. There are four inequivalent N1- sites. In the first N1- site, N1- is bonded in a bent 120 degrees geometry to one C4+ and one Te6+ atom. The N–Te bond length is 2.05 Å. In the second N1- site, N1- is bonded in a distorted single-bond geometry to one C4+ and one Cl1- atom. The N–Cl bond length is 1.70 Å. In the third N1- site, N1- is bonded in a bent 120 degrees geometry to one C4+ and one S2- atom. The N–S bond length is 1.59 Å. In the fourth N1- site, N1- is bonded in a single-bond geometry to one C4+ atom. Te6+ is bonded in a distorted square co-planar geometry to two equivalent N1- and two equivalent S2- atoms. Both Te–S bond lengths are 2.68 Å. S2- is bonded in a distorted single-bond geometry to one N1- and one Te6+ atom. Cl1- is bonded in a distorted single-bond geometry to one N1- atom.

36 MATERIALS SCIENCE↗
NASA NTRS1992

Venus lower thermosphere studies

Studies undertaken in this project have sought to understand lower thermospheric structure and dynamics (less than or equal to 145 km), particularly the processes responsible. This is a region just below the reach of in-situ instruments onboard PVO (Pioneer Venus Orbiter) during the first few diurnal cycles. PVO remote airglow observations (nitric oxide, O2, visible, O 1304A) have been coupled with ground-based observations (CO densities, winds, temperatures, O2 IR nightglow) to address the behavior of lower thermospheric winds and chemistry over 95 to 150 km. This interpretation of PVO and related data is accomplished by using the NCAR Venus thermospheric general circulation model (VTGCM) (Bougher et al., 1988; 1990). This model has been modified over the last two years to improve its ability to calculate O, CO, and O2 densities, temperatures, nightglow, and subsolar-to-antisolar and zonal winds over 95 to 150 km (Bougher and Borucki, 1992). Our VTGCM studies show that: (1) O2 visible and IR nightglow distributions can be used to trace lower thermosphere / upper mesosphere winds over 100-130 km. Typically, weak zonal winds (less than or equal to 25 m/sec) and nightglow maximum patches near 0100 LT prevail. Occasionally, strong zonal winds (30-60 m/sec) and airglow patches peaking near 0300 LT characterize the Venus lower thermosphere. (2) It is clear that the dynamics of the Venus 90-130 km region is highly variable on time scales as short as an hour. This is most likely due to the time variable nature of upward propagating gravity waves, which grow in amplitude and eventually break. The resulting turbulence gives rise to local time variable eddy diffusion and momentum drag, both of which strongly impact global density and nightglow distributions. (3) The oxygen chemistry (O, O2, etc.) over 90-120 km is strongly dependent on HO(x) and CLO(x) tracer species that must be properly included in any coupled chemical dynamical model. (4) The density profiles of light species (O, CO, N, He) are strongly affected by large-scale transport by the winds. Strong eddy diffusion is not a suitable model parameterization for approximating these light species, especially for extrapolation into the region below 140 km where PVO in-situ data is lacking. Instead, the fully coupled chemical dynamical VTGCM model should be used to improve estimates of densities within the VTS3 empirical model (Hedin et al., 1983) below 140 km.

Bougher, Stephen W.↗
NASA NTRS1999

High-Altitude Aircraft and Balloon-Borne Observations of OH, HO2, ClO, BrO, NO2, ClONO2, ClOOCl, H2O, and O3 in Earth's Stratosphere

Using observations from balloon-borne instruments and aircraft-borne instruments the investigation arrived at the following developments.: (1) Determination of the dominant catalytic cycles that destroy ozone in the lower stratosphere; (2) The partial derivatives of the rate limiting steps are observables in the lower stratosphere; (3) Recognition that the "Low NOx" condition is the regime that holds the greatest potential for misjudgement of Ozone loss rates; (4) Mapping of the Bromine radical contribution to the ozone destruction rate in the lower stratosphere; (5) Observation of OH, HO2 and ClO in the plume of the Concorde SST in the stratosphere; (6) Determination of the diurnal behavior of OH in the lower stratosphere; (7) Observed OH and H02 in the Troposphere and the interrelationship between Ozone and OH, HO2, CO and NO; (8) Analysis of the Catalytic Production of Ozone and Reactions that Couple OH and H02 in the Troposphere; (9) The continuing development of the understanding of the Tropopause temperatures, water vapor mixing ratios, and vertical advection and the mixing in of mid-latitude air; (10) Performed Multiple Tracer Analyses as a diagnostic of water vapor intrusion into the "Middle World" (i.e., the lowermost stratsophere); (11) Flight testing of a new instrument for the In Situ detection of ClON02 from the ER-2; (12) Laser induced fluorescence detection of NO2. There is included an in depth discussion of each of these developments and observations.

Anderson, James G.↗
DOE OSTI2024

Transport of metformin metabolites by guanidinium exporters of the small multidrug resistance family

Proteins from the small multidrug resistance (SMR) family are frequently associated with horizontally transferred multidrug resistance gene arrays found in bacteria from wastewater and the human-adjacent biosphere. Recent studies suggest that a subset of SMR transporters might participate in the metabolism of the common pharmaceutical metformin by bacterial consortia. Here, we show that both genomic and plasmid-associated transporters of the SMRGdx functional subtype export byproducts of microbial metformin metabolism, with particularly high export efficiency for guanylurea. We use solid-supported membrane electrophysiology to evaluate the transport kinetics for guanylurea and native substrate guanidinium by four representative SMRGdx homologs. Using an internal reference to normalize independent electrophysiology experiments, we show that transport rates are comparable for genomic and plasmid-associated SMRGdx homologs, and using a proteoliposome-based transport assay, we show that 2 proton:1 substrate transport stoichiometry is maintained. Additional characterization of guanidinium and guanylurea export properties focuses on the structurally characterized homolog, Gdx-Clo, for which we examined the pH dependence and thermodynamics of substrate binding and solved an x-ray crystal structure with guanylurea bound. Together, these experiments contribute in two main ways. By providing the first detailed kinetic examination of the structurally characterized SMRGdx homolog Gdx-Clo, they provide a functional framework that will inform future mechanistic studies of this model transport protein. Second, this study casts light on a potential role for SMRGdx transporters in microbial handling of metformin and its microbial metabolic byproducts, providing insight into how native transport physiologies are co-opted to contend with new selective pressures.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗