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Zr2TcGa crystallizes in the orthorhombic Immm space group. The structure is one-dimensional and consists of two Zr2TcGa ribbons oriented in the (1, 0, 0) direction. Zr is bonded in a linear geometry to one Tc and one Ga atom. The Zr–Tc bond length is 2.23 Å. The Zr–Ga bond length is 2.78 Å. Tc is bonded in a linear geometry to two equivalent Zr atoms. Ga is bonded in a linear geometry to two equivalent Zr atoms.
Zr2TcIr crystallizes in the orthorhombic Immm space group. The structure is one-dimensional and consists of two Zr2TcIr ribbons oriented in the (1, 0, 0) direction. Zr is bonded in a linear geometry to one Tc and one Ir atom. The Zr–Tc bond length is 2.22 Å. The Zr–Ir bond length is 2.37 Å. Tc is bonded in a linear geometry to two equivalent Zr atoms. Ir is bonded in a linear geometry to two equivalent Zr atoms.
Zr2TcCd crystallizes in the orthorhombic Immm space group. The structure is one-dimensional and consists of two Zr2TcCd ribbons oriented in the (1, 0, 0) direction. Zr is bonded in a linear geometry to one Tc and one Cd atom. The Zr–Tc bond length is 2.25 Å. The Zr–Cd bond length is 3.14 Å. Tc is bonded in a linear geometry to two equivalent Zr atoms. Cd is bonded in a linear geometry to two equivalent Zr atoms.
Zr2TcCu crystallizes in the orthorhombic Immm space group. The structure is one-dimensional and consists of two Zr2TcCu ribbons oriented in the (1, 0, 0) direction. Zr is bonded in a linear geometry to one Tc and one Cu atom. The Zr–Tc bond length is 2.28 Å. The Zr–Cu bond length is 2.69 Å. Tc is bonded in a linear geometry to two equivalent Zr atoms. Cu is bonded in a linear geometry to two equivalent Zr atoms.
NbW2Tc crystallizes in the orthorhombic Immm space group. The structure is one-dimensional and consists of two NbW2Tc ribbons oriented in the (1, 0, 0) direction. Nb is bonded in a linear geometry to two equivalent W atoms. Both Nb–W bond lengths are 2.32 Å. W is bonded in a linear geometry to one Nb and one Tc atom. The W–Tc bond length is 2.24 Å. Tc is bonded in a linear geometry to two equivalent W atoms.
Ti2MoTc crystallizes in the orthorhombic Immm space group. The structure is one-dimensional and consists of two Ti2MoTc ribbons oriented in the (1, 0, 0) direction. Ti is bonded in a linear geometry to one Mo and one Tc atom. The Ti–Mo bond length is 2.27 Å. The Ti–Tc bond length is 2.12 Å. Mo is bonded in a linear geometry to two equivalent Ti atoms. Tc is bonded in a linear geometry to two equivalent Ti atoms.
BeZr2Tc crystallizes in the orthorhombic Immm space group. The structure is one-dimensional and consists of two BeZr2Tc ribbons oriented in the (1, 0, 0) direction. Be is bonded in a linear geometry to two equivalent Zr atoms. Both Be–Zr bond lengths are 2.72 Å. Zr is bonded in a linear geometry to one Be and one Tc atom. The Zr–Tc bond length is 2.25 Å. Tc is bonded in a linear geometry to two equivalent Zr atoms.
Nb2TcNi crystallizes in the orthorhombic Immm space group. The structure is one-dimensional and consists of two Nb2TcNi ribbons oriented in the (1, 0, 0) direction. Nb is bonded in a linear geometry to one Tc and one Ni atom. The Nb–Tc bond length is 2.29 Å. The Nb–Ni bond length is 2.38 Å. Tc is bonded in a linear geometry to two equivalent Nb atoms. Ni is bonded in a linear geometry to two equivalent Nb atoms.
Zr2TcIr is Heusler structured and crystallizes in the cubic Fm-3m space group. The structure is three-dimensional. Zr is bonded in a body-centered cubic geometry to four equivalent Tc and four equivalent Ir atoms. All Zr–Tc bond lengths are 2.86 Å. All Zr–Ir bond lengths are 2.86 Å. Tc is bonded in a body-centered cubic geometry to eight equivalent Zr atoms. Ir is bonded in a body-centered cubic geometry to eight equivalent Zr atoms.
Zr2TcRu crystallizes in the orthorhombic Immm space group. The structure is one-dimensional and consists of two Zr2TcRu ribbons oriented in the (1, 0, 0) direction. Zr is bonded in a linear geometry to one Tc and one Ru atom. The Zr–Tc bond length is 2.31 Å. The Zr–Ru bond length is 2.29 Å. Tc is bonded in a linear geometry to two equivalent Zr atoms. Ru is bonded in a linear geometry to two equivalent Zr atoms.
TcNi crystallizes in the hexagonal P-6m2 space group. The structure is three-dimensional. Tc3- is bonded to six equivalent Tc3- and six equivalent Ni3+ atoms to form a mixture of edge, face, and corner-sharing TcTc6Ni6 cuboctahedra. All Tc–Tc bond lengths are 2.65 Å. All Tc–Ni bond lengths are 2.60 Å. Ni3+ is bonded in a 6-coordinate geometry to six equivalent Tc3- atoms.
Hf2TcNi is Heusler structured and crystallizes in the cubic Fm-3m space group. The structure is three-dimensional. Hf is bonded in a body-centered cubic geometry to four equivalent Tc and four equivalent Ni atoms. All Hf–Tc bond lengths are 2.80 Å. All Hf–Ni bond lengths are 2.80 Å. Tc is bonded in a body-centered cubic geometry to eight equivalent Hf atoms. Ni is bonded in a body-centered cubic geometry to eight equivalent Hf atoms.
Hf2TcCu crystallizes in the orthorhombic Immm space group. The structure is one-dimensional and consists of two Hf2TcCu ribbons oriented in the (1, 0, 0) direction. Hf is bonded in a linear geometry to one Tc and one Cu atom. The Hf–Tc bond length is 2.25 Å. The Hf–Cu bond length is 2.75 Å. Tc is bonded in a linear geometry to two equivalent Hf atoms. Cu is bonded in a linear geometry to two equivalent Hf atoms.
Occasionally large errors have occurred in some of the calorimeters used in the arc jet facilities. Some slug calorimeters would measure twice the expected heat flux and some Coaxial TC calorimeters would measure half the expected heat flux. While these errors in heat flux measurements are easy to identify and discard / dismiss, the concern is that less spectacular errors are difficult to detect. This inspired a critical look at the calorimetry used to measure stagnation heat flux in the NASA Ames Arc Jet facilities. Numerous sources of error were investigated, and the culprit in the case of slug calorimeters was determined to be leaks in the stagnation calorimeter assembly resulting in flow along the side of the slug. In the case of the coaxial TC calorimeter, it is hypothesized that in some calorimeters there is a partial electrical short circuit in the Coaxial TC sensor element somewhere in the middle of the calorimeter.
Abstract Three oleogelator molecules (Triacontane (TC), Stearic acid (SA), and Behenyl Lignocerate (BL)) were studied individually, in pairs, or all together to make an oleogel using triolein as the oil. WAXS, SAXS and USAXS were used to elucidate the solid structures from angstroms to a few micrometers. A two‐dimensional mapping of atomic positions for each molecule was carried out to understand the crystalline multilayer structures formed. We assumed that the molecules were rigidly extended and that they underwent no significant (hindered) rotations so that the free energy is determined by the Lennard‐Jones interactions of closely packed multilayers. TC molecules were predicted to form a tilt angle of , yielding a SAXS line at Å ─1 , in acceptable agreement with the measured . For SA crystals (predicted) yielding a SAXS line at compared to (observed). No mixed crystals were observed for any pair of molecules or when all three were used. USAXS data showed that SA forms large nanocrystals compared to TC and BL. All three combinations of molecular pairs showed basic scatterers smaller or similar to those of individual molecules. The theory presented here, together with the experimental results, showed why no mixed crystals are formed from two or all three molecules. Data from the USAXS region suggested that, when using all three molecules, a more compact fractal structure was obtained, compared with those if one or two of the molecules were used.
Abstract Recently, the significant improvements in the surface and contact passivation of silicon (Si) solar cells as well as their bulk quality have shifted their operating point to higher injections. Hence, they are less dependent on wafer doping. This shift opens an opportunity of using high‐resistivity wafers for practical photovoltaic applications, introducing a promising approach to push the cell efficiency towards the intrinsic limit and to improve the module reliability by increasing the cell breakdown voltage. Therefore, insights into the performance of Si solar cells using high‐resistivity wafers at various operating temperatures are of significant interest. In this study, we investigate the temperature‐ and illumination‐dependent performance of Si heterojunction (SHJ) solar cells using a wide range of wafer resistivities (between 3 and 1000 Ω⋅cm). Although a reduction in the passivation quality of the passivating contacts is observed at elevated temperature, the impact on the temperature coefficient of the open‐circuit voltage (TC V oc )—the dominant contributor to the temperature coefficient (TC) of the cell efficiency—is very limited. Their TC V oc are still dominated by the temperature dependence of the effective intrinsic carrier concentration. Furthermore, we also find that the investigated cells are more sensitive to temperature variation at lower illumination intensities. It is noteworthy that the efficiency of the cells fabricated using high‐resistivity wafers is comparable to that of the reference cells at any given temperature, highlighting the potential of using high‐resistivity wafers for solar cells.
Here, the Fluoride-salt-cooled High-temperature Reactor (FHR) is a promising Generation IV nuclear reactor due to its improved safety design, near atmospheric working pressure, and high electric power conversion efficiency. However, control of radioactive fission gases, such as tritium, is a critical issue in FHRs due to the significantly larger production rate and potentially larger leakage rate of tritium compared to those in Light Water Reactors (LWRs). Therefore, this study proposes two mitigation strategies for tritium in FHRs: Double-Wall Heat eXchanger with a Tritium Carrier (DWHX-TC) option and Single-Wall Heat eXchanger with a Tritium Barrier (SWHX-TB) option. For the DWHX-TC option, two tube surface configurations, i.e., plain and fluted tubes, and four tritium carriers, i.e., helium, FLiBe, FLiNaK, and KF-ZrF 4 , are initially considered, among which the best tube configuration and promising tritium carrier are then selected and used for design optimization of the DWHX. For the SWHX-TB option, two cases, tritium barriers with and without cracks, are investigated in this study. In addition, the two mitigation strategies are evaluated by an in-house, one-dimensional, coupled HEat and MAss Transfer (HEMAT) code developed to predict the leakage rate of tritium in nuclear systems. Our analysis shows that (1) a double-wall configuration using fluted tubes as both the inner and outer tubes is better than other double-wall configurations investigated; (2) helium, as a tritium carrier, is superior to other candidates, including FLiBe, FLiNaK, and KF-ZrF 4 ; (3) the leakage rate of tritium (into the atmosphere) is reduced from 3400 Ci/day, taking the Advanced High-Temperature Reactor (AHTR) as a reference, to 4.0 Ci/day for an optimum design of the DWHX-TC option using helium as the tritium carrier and 1.7 Ci/day for an optimum design of the SWHX-TB option using 30-µm thick silicon carbide (SiC) as the tritium barrier (no cracks); and (4) potential cracks in tritium barriers may significantly deteriorate mass transfer performance of the SWHX-TB option. For example, a cracking rate of 0.1% leads to an increase of 694.1% in the leakage rate under the conditions investigated.
How aerosols affect the weather and climate system has received increasing attention. This study finds a significant negative correlation between March–May eastern China aerosol optical depth (AOD) and July–November western North Pacific (WNP) tropical cyclone (TC) frequency during 2003–2020. This time period spans when several aerosol reanalyses are available and both Terra and Aqua Moderate Resolution Imaging Spectroradiometer AOD retrievals are assimilated therein. Composite analyses and budget analyses of dynamical genesis potential indices indicate the importance of large-scale environmental factors, especially vertical velocity and vertical wind shear, associated with changes in AOD that in turn modulate changes in WNP TC frequency. Increased eastern China AOD may facilitate negative Pacific meridional mode development via modulation of the westerly jet, which then forces an anticyclonic circulation over the WNP basin. Increased AOD can also directly decrease the inter-hemispheric temperature differential and increases the intra-hemispheric temperature differential between the equator and the mid-latitudes, thus weakening ascending motion and enhancing vertical wind shear over the WNP, especially the southeastern portion of the basin. Further, all of these large-scale environment changes induced by increased eastern China AOD tend to suppress WNP TCs. This study highlights the potential influence of eastern China aerosol loadings on WNP TCs, thus improving our understanding of TC climate variability over the WNP.