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The First Year of KOKEE12M-WETTZ13S VGOS Intensive Scheduling: Status and Efforts Towards Improvement

The KOKEE12M-WETTZ13S (K2-Ws) Intensive series began on January 4, 2021. Evaluation of the first year of schedules has shown that the series is performing reasonably weel, but the schedules could be improved. For example, the number of scheduled observations in a typical 2021 K2-Ws session is approximately half that of the first few MACGO12M-WETTZ13S Intensive sessions, and scheduling fewer observations negatively impats UT1 results. Also, preliminary analysis of the scheduled and achieve SNRs of the K2-Ws observations and the SNRs' ratios shows examples where the achieved SNRs are either too high, indicating long observations that could have been replaced by a greater number of shorter observations, or too low, indicating a lack of robustness that could lead to observation loss. In this poster, we describe key aspects of how the K2-Ws Intensives have been scheduled in 2021. Then we discuss the areas of concern and the status of efforts to make improvements in these areas.

Karen Baver↗

DOE OSTI2020

The performance evaluation of direct detection electron energy-loss spectroscopy at 200 kV and 80 kV accelerating voltages

Direct electron detectors (DeDs) have been widely used for imaging studies because of their higher beam sensitivity, lower noise, improved pixel resolution, etc. However, there have been limited studies related to the performance in spectroscopic applications for the direct electron detection. Hereby, taking the advantage of the DeD installed on a high-performance electron energy-loss spectrometer, we systematically studied the performance of a DeD (Gatan's K2 IS) fitted on an aberration-corrected transmission electron microscope (TEM) equipped with an electron monochromator. Using SrTiO3 as the model system, the point spread function in the zero-loss region of the spectrum and the performance for core loss spectroscopy have been investigated under both 200 kV and 80 kV operating conditions. We demonstrate that the K2 detector can achieve an overall better performance at 200 kV than a charge coupled device (CCD) detector. At 80 kV, the K2 DeD is still better than a CCD, except for the relative broad tails of the zero-loss peak. The signal-to-noise ratio is very close for DeD and CCD under 80 kV. Based on our data obtained at different operating voltages, it is clear that DeD will benefit the microscopy community and boost the development of cutting-edge materials science studies by pushing the frontiers in electron energy-loss spectroscopy.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗

DOE OSTI2016

Temperature dependent behavior of localized and delocalized electrons in nitrogen-doped 6H SiC crystals as studied by electron spin resonance

We have studied the temperature behavior of the electron spin resonance (ESR) spectra of nitrogen (N) donors in n-type 6H SiC crystals grown by Lely and sublimation sandwich methods (SSM) with donor concentration of 10{sup 17 }cm{sup −3} at T = 60–150 K. A broad signal in the ESR spectrum was observed at T ≥ 80 K with Lorentzian lineshape and g{sub ||} = 2.0043(3), g{sub ⊥} = 2.0030(3), which was previously assigned in the literature to the N donors in the 1s(E) excited state. Based on the analysis of the ESR lineshape, linewidth and g-tensor we attribute this signal to the conduction electrons (CE). The emergence of the CE ESR signal at T > 80 K was explained by the ionization of electrons from the 1s(A{sub 1}) ground and 1s(E) excited states of N donors to the conduction band while the observed reduction of the hyperfine (hf) splitting for the N{sub k1,k2} donors with the temperature increase is attributed to the motional narrowing effect of the hf splitting. The temperature dependence of CE ESR linewidth is described by an exponential law (Orbach process) with the activation energy corresponding to the energy separation between 1s(A{sub 1}) and 1s(E) energy levels for N residing at quasi-cubic sites (N{sub k1,k2}). The theoretical analysis of the temperature dependence of microwave conductivity measured by the contact-free method shows that due to the different position of the Fermi level in two samples the ionization of free electrons occurs from the energy levels of N{sub k1,k2} donors in Lely grown samples and from the energy level of N{sub h} residing at hexagonal position in 6H SiC grown by SSM.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗

DOE OSTI2012

SUBSTELLAR-MASS COMPANIONS TO THE K-GIANTS HD 240237, BD +48 738, AND HD 96127

We present the discovery of substellar-mass companions to three giant stars by the ongoing Penn State-Torun Planet Search conducted with the 9.2 m Hobby-Eberly Telescope. The most massive of the three stars, K2-giant HD 240237, has a 5.3 M{sub J} minimum mass companion orbiting the star at a 746 day period. The K0-giant BD +48 738 is orbited by a {>=}0.91 M{sub J} planet which has a period of 393 days and shows a nonlinear, long-term radial velocity (RV) trend that indicates a presence of another, more distant companion, which may have a substellar mass or be a low-mass star. The K2-giant HD 96127 has a {>=}4.0 M{sub J} mass companion in a 647 day orbit around the star. The two K2-giants exhibit a significant RV noise that complicates the detection of low-amplitude, periodic variations in the data. If the noise component of the observed RV variations is due to solar-type oscillations, we show, using all the published data for the substellar companions to giants, that its amplitude is anti-correlated with stellar metallicity.

79 ASTRONOMY AND ASTROPHYSICS↗

DOE OSTI2012

METALLICITY AND TEMPERATURE INDICATORS IN M DWARF K-BAND SPECTRA: TESTING NEW AND UPDATED CALIBRATIONS WITH OBSERVATIONS OF 133 SOLAR NEIGHBORHOOD M DWARFS

We present K-band spectra for 133 nearby (d < 33 ps) M dwarfs, including 18 M dwarfs with reliable metallicity estimates (as inferred from an FGK type companion), 11 M dwarf planet hosts, more than 2/3 of the M dwarfs in the northern 8 pc sample, and several M dwarfs from the LSPM catalog. From these spectra, we measure equivalent widths of the Ca and Na lines, and a spectral index quantifying the absorption due to H{sub 2}O opacity (the H{sub 2}O-K2 index). Using empirical spectral type standards and synthetic models, we calibrate the H{sub 2}O-K2 index as an indicator of an M dwarf's spectral type and effective temperature. We also present a revised relationship that estimates the [Fe/H] and [M/H] metallicities of M dwarfs from their Na I, Ca I, and H{sub 2}O-K2 measurements. Comparisons to model atmosphere provide a qualitative validation of our approach, but also reveal an overall offset between the atomic line strengths predicted by models as compared to actual observations. Our metallicity estimates also reproduce expected correlations with Galactic space motions and H{alpha} emission line strengths, and return statistically identical metallicities for M dwarfs within a common multiple system. Finally, we find systematic residuals between our H{sub 2}O-based spectral types and those derived from optical spectral features with previously known sensitivity to stellar metallicity, such as TiO, and identify the CaH1 index as a promising optical index for diagnosing the metallicities of near-solar M dwarfs.

79 ASTRONOMY AND ASTROPHYSICS↗

DOE OSTI2015

Two transiting earth-size planets near resonance orbiting a nearby cool star

Discoveries from the prime Kepler mission demonstrated that small planets (<3 R{sub ⊕}) are common outcomes of planet formation. While Kepler detected many such planets, all but a handful orbit faint, distant stars and are not amenable to precise follow up measurements. Here, we report the discovery of two small planets transiting K2-21, a bright (K = 9.4) M0 dwarf located 65±6 pc from Earth. We detected the transiting planets in photometry collected during Campaign 3 of NASA’s K2 mission. Analysis of transit light curves reveals that the planets have small radii compared to their host star, R{sub P}/R{sub ⋆} = 2.60±0.14% and 3.15±0.20%, respectively. We obtained follow up NIR spectroscopy of K2-21 to constrain host star properties, which imply planet sizes of 1.59 ± 0.43 R{sub ⊕} and 1.92 ± 0.53 R{sub ⊕}, respectively, straddling the boundary between high-density, rocky planets and low-density planets with thick gaseous envelopes. The planets have orbital periods of 9.32414 days and 15.50120 days, respectively, and a period ratio P{sub c}/P{sub b} = 1.6624, very near to the 5:3 mean motion resonance, which may be a record of the system’s formation history. Transit timing variations due to gravitational interactions between the planets may be detectable using ground-based telescopes. Finally, this system offers a convenient laboratory for studying the bulk composition and atmospheric properties of small planets with low equilibrium temperatures.

79 ASTRONOMY AND ASTROPHYSICS↗

DOE OSTI2020

Materials Data on K(BH)5 by Materials Project

K2(BH)9BH crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional and consists of four boranediylradical molecules and one K2(BH)9 framework. In the K2(BH)9 framework, there are two inequivalent K sites. In the first K site, K is bonded in a 8-coordinate geometry to eight H atoms. There are a spread of K–H bond distances ranging from 2.67–3.05 Å. In the second K site, K is bonded in a 8-coordinate geometry to eight H atoms. There are a spread of K–H bond distances ranging from 2.79–3.07 Å. There are nine inequivalent B sites. In the first B site, B is bonded in a distorted single-bond geometry to one H atom. The B–H bond length is 1.21 Å. In the second B site, B is bonded in a distorted single-bond geometry to one H atom. The B–H bond length is 1.21 Å. In the third B site, B is bonded in a distorted single-bond geometry to one H atom. The B–H bond length is 1.21 Å. In the fourth B site, B is bonded in a distorted single-bond geometry to one H atom. The B–H bond length is 1.21 Å. In the fifth B site, B is bonded in a distorted single-bond geometry to one H atom. The B–H bond length is 1.20 Å. In the sixth B site, B is bonded in a distorted single-bond geometry to one H atom. The B–H bond length is 1.20 Å. In the seventh B site, B is bonded in a distorted single-bond geometry to one H atom. The B–H bond length is 1.21 Å. In the eighth B site, B is bonded in a distorted single-bond geometry to one H atom. The B–H bond length is 1.21 Å. In the ninth B site, B is bonded in a distorted single-bond geometry to one H atom. The B–H bond length is 1.21 Å. There are nine inequivalent H sites. In the first H site, H is bonded in a distorted bent 120 degrees geometry to one K and one B atom. In the second H site, H is bonded in a single-bond geometry to two K and one B atom. In the third H site, H is bonded in a distorted single-bond geometry to two equivalent K and one B atom. In the fourth H site, H is bonded in a distorted single-bond geometry to two K and one B atom. In the fifth H site, H is bonded in a single-bond geometry to two equivalent K and one B atom. In the sixth H site, H is bonded in a distorted single-bond geometry to two equivalent K and one B atom. In the seventh H site, H is bonded in a distorted single-bond geometry to two K and one B atom. In the eighth H site, H is bonded in a distorted single-bond geometry to one K and one B atom. In the ninth H site, H is bonded in a single-bond geometry to two K and one B atom.

36 MATERIALS SCIENCE↗

DOE OSTI2020

Materials Data on K4Ru(NO2)6 by Materials Project

Ru(K2(NO2)3)2 crystallizes in the trigonal R-3 space group. The structure is three-dimensional and consists of three rutenio molecules and one K2(NO2)3 framework. In the K2(NO2)3 framework, there are two inequivalent K1+ sites. In the first K1+ site, K1+ is bonded in a 9-coordinate geometry to nine O2- atoms. There are a spread of K–O bond distances ranging from 2.85–3.25 Å. In the second K1+ site, K1+ is bonded in a 9-coordinate geometry to nine O2- atoms. There are three shorter (2.89 Å) and six longer (2.90 Å) K–O bond lengths. N+2.33+ is bonded in a bent 120 degrees geometry to two O2- atoms. Both N–O bond lengths are 1.27 Å. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted single-bond geometry to three K1+ and one N+2.33+ atom. In the second O2- site, O2- is bonded in a distorted single-bond geometry to three K1+ and one N+2.33+ atom.

36 MATERIALS SCIENCE↗

DOE OSTI2020

Materials Data on K2Hg3S3O10 by Materials Project

K2(SO3)3Hg3O crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional and consists of four Hg3O clusters and one K2(SO3)3 framework. In each Hg3O cluster, there are two inequivalent Hg2+ sites. In the first Hg2+ site, Hg2+ is bonded in a 1-coordinate geometry to one O2- atom. The Hg–O bond length is 2.15 Å. In the second Hg2+ site, Hg2+ is bonded in a 1-coordinate geometry to one O2- atom. The Hg–O bond length is 2.11 Å. O2- is bonded in a trigonal non-coplanar geometry to three Hg2+ atoms. In the K2(SO3)3 framework, K1+ is bonded in a 9-coordinate geometry to nine O2- atoms. There are a spread of K–O bond distances ranging from 2.87–3.40 Å. There are two inequivalent S4+ sites. In the first S4+ site, S4+ is bonded in a trigonal non-coplanar geometry to three O2- atoms. All S–O bond lengths are 1.49 Å. In the second S4+ site, S4+ is bonded in a trigonal non-coplanar geometry to three O2- atoms. There are a spread of S–O bond distances ranging from 1.47–1.49 Å. There are five inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted single-bond geometry to two equivalent K1+ and one S4+ atom. In the second O2- site, O2- is bonded in a distorted single-bond geometry to one K1+ and one S4+ atom. In the third O2- site, O2- is bonded in a distorted single-bond geometry to three equivalent K1+ and one S4+ atom. In the fourth O2- site, O2- is bonded in a distorted single-bond geometry to three equivalent K1+ and one S4+ atom. In the fifth O2- site, O2- is bonded in a distorted single-bond geometry to one S4+ atom.

36 MATERIALS SCIENCE↗

DOE OSTI2019

Materials Data on K2H14Rh2N12O17 by Materials Project

K2(NO2)7(Rh)2(NH3)4NO2H2O crystallizes in the triclinic P-1 space group. The structure is two-dimensional and consists of eight ammonia molecules; two hydroxylamine, n-hydroxy- molecules; four rhodium molecules; two water molecules; and one K2(NO2)7 sheet oriented in the (0, 0, 1) direction. In the K2(NO2)7 sheet, there are two inequivalent K1+ sites. In the first K1+ site, K1+ is bonded in a 9-coordinate geometry to nine O2- atoms. There are a spread of K–O bond distances ranging from 2.66–3.30 Å. In the second K1+ site, K1+ is bonded in a 10-coordinate geometry to ten O2- atoms. There are a spread of K–O bond distances ranging from 2.84–3.33 Å. There are seven inequivalent N1+ sites. In the first N1+ site, N1+ is bonded in a bent 120 degrees geometry to two O2- atoms. There is one shorter (1.24 Å) and one longer (1.26 Å) N–O bond length. In the second N1+ site, N1+ is bonded in a bent 120 degrees geometry to two O2- atoms. Both N–O bond lengths are 1.25 Å. In the third N1+ site, N1+ is bonded in a bent 120 degrees geometry to two O2- atoms. Both N–O bond lengths are 1.25 Å. In the fourth N1+ site, N1+ is bonded in a bent 120 degrees geometry to two O2- atoms. Both N–O bond lengths are 1.25 Å. In the fifth N1+ site, N1+ is bonded in a bent 120 degrees geometry to two O2- atoms. Both N–O bond lengths are 1.25 Å. In the sixth N1+ site, N1+ is bonded in a bent 120 degrees geometry to two O2- atoms. Both N–O bond lengths are 1.25 Å. In the seventh N1+ site, N1+ is bonded in a bent 120 degrees geometry to two O2- atoms. Both N–O bond lengths are 1.25 Å. There are fourteen inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted single-bond geometry to two K1+ and one N1+ atom. In the second O2- site, O2- is bonded in a single-bond geometry to one K1+ and one N1+ atom. In the third O2- site, O2- is bonded in a single-bond geometry to one K1+ and one N1+ atom. In the fourth O2- site, O2- is bonded in a single-bond geometry to one N1+ atom. In the fifth O2- site, O2- is bonded in a distorted single-bond geometry to two equivalent K1+ and one N1+ atom. In the sixth O2- site, O2- is bonded in a single-bond geometry to one N1+ atom. In the seventh O2- site, O2- is bonded in a distorted single-bond geometry to two K1+ and one N1+ atom. In the eighth O2- site, O2- is bonded in a distorted single-bond geometry to three K1+ and one N1+ atom. In the ninth O2- site, O2- is bonded in a single-bond geometry to one K1+ and one N1+ atom. In the tenth O2- site, O2- is bonded in a distorted single-bond geometry to one K1+ and one N1+ atom. In the eleventh O2- site, O2- is bonded in a distorted single-bond geometry to two K1+ and one N1+ atom. In the twelfth O2- site, O2- is bonded in a single-bond geometry to one K1+ and one N1+ atom. In the thirteenth O2- site, O2- is bonded in a distorted single-bond geometry to two K1+ and one N1+ atom. In the fourteenth O2- site, O2- is bonded in a distorted single-bond geometry to one K1+ and one N1+ atom.

36 MATERIALS SCIENCE↗

DOE OSTI2019

Materials Data on K2Re3TeC3(SN)3 by Materials Project

K2(CN)3Re3TeS3 crystallizes in the cubic Ia-3 space group. The structure is three-dimensional and consists of eight Re3TeS3 clusters and one K2(CN)3 framework. In each Re3TeS3 cluster, Re+3.67+ is bonded in a distorted rectangular see-saw-like geometry to one Te2- and three equivalent S2- atoms. The Re–Te bond length is 2.73 Å. There are a spread of Re–S bond distances ranging from 2.41–2.43 Å. Te2- is bonded in a 6-coordinate geometry to three equivalent Re+3.67+ atoms. S2- is bonded in a 5-coordinate geometry to three equivalent Re+3.67+ atoms. In the K2(CN)3 framework, there are two inequivalent K1+ sites. In the first K1+ site, K1+ is bonded in a distorted octahedral geometry to six equivalent N3- atoms. All K–N bond lengths are 2.98 Å. In the second K1+ site, K1+ is bonded in a 2-coordinate geometry to two equivalent N3- atoms. Both K–N bond lengths are 2.92 Å. C+1.33+ is bonded in a single-bond geometry to one N3- atom. The C–N bond length is 1.18 Å. N3- is bonded in a 1-coordinate geometry to two K1+ and one C+1.33+ atom.

36 MATERIALS SCIENCE↗

DOE OSTI2020

Materials Data on K2P3NO12 by Materials Project

(K2(PO4)3)2N2 crystallizes in the tetragonal I-42d space group. The structure is three-dimensional and consists of four ammonia molecules and one K2(PO4)3 framework. In the K2(PO4)3 framework, K is bonded in a 8-coordinate geometry to eight O atoms. There are a spread of K–O bond distances ranging from 2.81–2.99 Å. There are two inequivalent P sites. In the first P site, P is bonded in a tetrahedral geometry to four O atoms. There is two shorter (1.54 Å) and two longer (1.55 Å) P–O bond length. In the second P site, P is bonded in a tetrahedral geometry to four equivalent O atoms. All P–O bond lengths are 1.55 Å. There are three inequivalent O sites. In the first O site, O is bonded in a single-bond geometry to one K and one P atom. In the second O site, O is bonded in a distorted single-bond geometry to one K and one P atom. In the third O site, O is bonded in a distorted single-bond geometry to two equivalent K and one P atom.

36 MATERIALS SCIENCE↗

DOE OSTI2016

HUBBLE SPACE TELESCOPE CONSTRAINTS ON THE WINDS AND ASTROSPHERES OF RED GIANT STARS

We report on an ultraviolet spectroscopic survey of red giants observed by the Hubble Space Telescope , focusing on spectra of the Mg ii h and k lines near 2800 Å in order to study stellar chromospheric emission, winds, and astrospheric absorption. We focus on spectral types between K2 III and M5 III, a spectral type range with stars that are noncoronal, but possessing strong, chromospheric winds. We find a very tight relation between Mg ii surface flux and photospheric temperature, supporting the notion that all K2-M5 III stars are emitting at a basal flux level. Wind velocities ( V {sub w} ) are generally found to decrease with spectral type, with V {sub w} decreasing from ∼40 km s{sup −1} at K2 III to ∼20 km s{sup −1} at M5 III. We find two new detections of astrospheric absorption, for σ Pup (K5 III) and γ Eri (M1 III). This absorption signature had previously only been detected for α Tau (K5 III). For the three astrospheric detections, the temperature of the wind after the termination shock (TS) correlates with V {sub w} , but is lower than predicted by the Rankine–Hugoniot shock jump conditions, consistent with the idea that red giant TSs are radiative shocks rather than simple hydrodynamic shocks. A full hydrodynamic simulation of the γ Eri astrosphere is provided to explore this further.

79 ASTRONOMY AND ASTROPHYSICS↗

NASA NTRS1977

Kinetics of the reactions of ClO with O and with NO

The rate constants k1, k2, and k3 for the reactions Cl + O3 yields ClO + O2 (1), ClO + O yields Cl + O2 (2), and ClO + NO yields Cl + NO2 (3), respectively, were measured by the discharge-flow technique, in which chlorine atoms are added to a flow of O3 and either O or NO in a helium carrier gas. The conditions of the experiment were such that the steady-state concentration ratios of Cl to ClO are simply interpretable in terms of the rate constant ratios k2/k3 or k3/k1. These rate constant ratios were measured over the range 220 to 298 K and combined with the directly determined k1 value to yield k2 and k3. The results are: k1 = 2.12 x 10 to the -11th exp(-157/T); k2 = 3.38 x 10 to -11th exp(75 plus or minus 40/T); and k3 = 1.13 x 10 to the -11th exp(200 plus or minus 30/T) cu cm/sec.

Zahniser, M. S.↗

NASA NTRS1992

Determination of stress intensity factors for interface cracks under mixed-mode loading

A simple technique was developed using conventional finite element analysis to determine stress intensity factors, K1 and K2, for interface cracks under mixed-mode loading. This technique involves the calculation of crack tip stresses using non-singular finite elements. These stresses are then combined and used in a linear regression procedure to calculate K1 and K2. The technique was demonstrated by calculating three different bimaterial combinations. For the normal loading case, the K's were within 2.6 percent of an exact solution. The normalized K's under shear loading were shown to be related to the normalized K's under normal loading. Based on these relations, a simple equation was derived for calculating K1 and K2 for mixed-mode loading from knowledge of the K's under normal loading. The equation was verified by computing the K's for a mixed-mode case with equal and normal shear loading. The correlation between exact and finite element solutions is within 3.7 percent. This study provides a simple procedure to compute K2/K1 ratio which has been used to characterize the stress state at the crack tip for various combinations of materials and loadings. Tests conducted over a range of K2/K1 ratios could be used to fully characterize interface fracture toughness.

Naik, Rajiv A.↗

DOE OSTI2024

Resolving Discrepancies Between Theory and Experiment for the NCN + H Reaction

Flame modeling studies have highlighted the role of branching in the kinetics for the prompt NO switch reaction, NCN + H. In this reaction, there is strong competition between the CH + N2 (R1) and HCN + N (R2) product channels. Increased branching towards reaction R2 promotes the subsequent formation of Fenimore or Prompt NO. Recent direct shock tube studies on this complex reaction conclude that branching to reaction R2 is much more favorable than the predicted branching from theoretical studies. The experimentally predicted prompt NO switch temperature (TS), i.e., the temperature at which k2/(k1+k2) = 0.5, is at 1670 K, in contrast to theory that predicts Ts > 3200 K. The present theory/modeling work was initiated to highlight potential causes for this significant discrepancy between experiment and theory. Our analysis of the simulations reported in the experimental studies indicate that including a fall-off representation for C2H5 radical dissociation (with C2H5 produced from C2H5I dissociation and acting as an H-atom source) has a noticeable influence on the simulations for NCN decay and HCN formation in the shock tube studies. With the inclusion of a theory-based pressure fall-off representation for C2H5 dissociation, we show that this radical persists for much longer timescales even at the high-temperatures in the shock tube studies. This persistence then facilitates the rapid conversion of reactive H-atoms to CH3 radicals at the shock tube conditions via the H + C2H5 → CH3 + CH3 reaction. An updated theoretical analysis for this classic addition-elimination reaction is also provided in this work. The rapid formation of CH3 radicals necessitates the inclusion of additional reactions to adequately simulate the NCN and HCN data. Our simulations conclude that, with the inclusion of these additional reactions, the NCN and HCN profiles can be reasonably well simulated by the most recent theoretical predictions.

Ethyl Radicals↗

DOE OSTI2014

Dynamic nuclear renography kinetic analysis: Four-compartment model for assessing kidney function

Dynamic nuclear renography method produces TACs of kidneys and bladder. Multiple TACs data can be further analyzed to obtain the overview of urinary system's condition. Tracer kinetic analysis was performed using four-compartment models. The system's model consist of four irreversible compartment with four transport constants (k1, k2, k3 and k4). The mathematical expressions of tracer's distributions is fitted to experimental data (TACs) resulting in model constants. This transport constants represent the urinary system behavior, and later can be used for analyzing system's condition. Different intervals of kinetics parameter are clearly shown by abnormal system with respect to the normal one. Furthermore, the system with delayed uptake has 82% lower uptake parameters (k1 and k2) than normal one. Meanwhile, the system with prolonged clearance time has its kinetics parameters k3 or k4 lower than the others. This model is promising for quantitatively describe urinary system's function especially if supplied with more data.

60 APPLIED LIFE SCIENCES↗

DOE OSTI2025

Nonlocal effects on thermal transport in hydrodynamic simulations of unmagnetized MagLIF-relevant gaspipes on NIF

We present simulations of heat flow relevant to gaspipe experiments on the National Ignition Facility to investigate kinetic effects on transport phenomena. D 2 and neopentane (C 5 H 12 ) filled targets are used to study the laser preheat stage of a MagLIF scheme where an axial magnetic field is sometimes applied to the target. Simulations were done with the radiation-MHD code HYDRA with a collision-dominated fluid model and the SNB nonlocal electron thermal conduction model. Using the SNB model to evolve the electron temperature increased the heat front propagation of neopentane gas targets compared to a local model by limiting radial heat flow. This increases electron temperature near the axis, which decreases laser absorption. We find that the effect of heat flow models on temperature profiles and laser propagation is modest. Beyond the SNB model, we utilize HYDRA to initialize plasma conditions for the Vlasov–Fokker–Planck K2 code. We run K2 until a quasi-steady state is reached and examine the impact of kinetic effects on heat transport. Although axial heat flow is well predicted by fluid models, the fluid model consistently overpredicts radial heat flow up to 150% in regions with the largest temperature gradient of D 2 filled gaspipes. On the other hand, the SNB nonlocal electron conduction model is found to be adequate for capturing kinetic heat flow in gaspipes.

Lau, Ryan Y. [Univ. of Colorado, Boulder, CO (Unit↗