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Tc2Al crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Tc is bonded in a 8-coordinate geometry to four equivalent Tc and four equivalent Al atoms. All Tc–Tc bond lengths are 2.62 Å. All Tc–Al bond lengths are 2.66 Å. Al is bonded in a body-centered cubic geometry to eight equivalent Tc atoms.
K3Tc2O3Cl8 crystallizes in the trigonal P3_121 space group. The structure is three-dimensional. there are two inequivalent K1+ sites. In the first K1+ site, K1+ is bonded in a 8-coordinate geometry to two equivalent O2- and six Cl1- atoms. Both K–O bond lengths are 2.83 Å. There are a spread of K–Cl bond distances ranging from 3.23–3.43 Å. In the second K1+ site, K1+ is bonded in a 10-coordinate geometry to ten Cl1- atoms. There are a spread of K–Cl bond distances ranging from 3.25–3.82 Å. Tc+5.50+ is bonded in a 4-coordinate geometry to four Cl1- atoms. There are a spread of Tc–Cl bond distances ranging from 2.33–2.41 Å. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one K1+ and one O2- atom. The O–O bond length is 1.31 Å. In the second O2- site, O2- is bonded in a bent 120 degrees geometry to two equivalent O2- atoms. There are four inequivalent Cl1- sites. In the first Cl1- site, Cl1- is bonded in a distorted single-bond geometry to two equivalent K1+ and one Tc+5.50+ atom. In the second Cl1- site, Cl1- is bonded in a 1-coordinate geometry to four K1+ and one Tc+5.50+ atom. In the third Cl1- site, Cl1- is bonded in a 1-coordinate geometry to four K1+ and one Tc+5.50+ atom. In the fourth Cl1- site, Cl1- is bonded in a 1-coordinate geometry to three K1+ and one Tc+5.50+ atom.
Tc3Pb is beta Cu3Ti-like structured and crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. Tc+0.67- is bonded to eight equivalent Tc+0.67- and four equivalent Pb2+ atoms to form distorted TcTc8Pb4 cuboctahedra that share corners with four equivalent PbTc12 cuboctahedra, corners with fourteen equivalent TcTc8Pb4 cuboctahedra, edges with six equivalent PbTc12 cuboctahedra, edges with twelve equivalent TcTc8Pb4 cuboctahedra, faces with four equivalent PbTc12 cuboctahedra, and faces with sixteen equivalent TcTc8Pb4 cuboctahedra. There are a spread of Tc–Tc bond distances ranging from 2.72–3.10 Å. There are two shorter (2.89 Å) and two longer (2.91 Å) Tc–Pb bond lengths. Pb2+ is bonded to twelve equivalent Tc+0.67- atoms to form PbTc12 cuboctahedra that share corners with six equivalent PbTc12 cuboctahedra, corners with twelve equivalent TcTc8Pb4 cuboctahedra, edges with eighteen equivalent TcTc8Pb4 cuboctahedra, faces with eight equivalent PbTc12 cuboctahedra, and faces with twelve equivalent TcTc8Pb4 cuboctahedra.
WTc3 is Uranium Silicide-like structured and crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. W5+ is bonded to twelve equivalent Tc+1.67- atoms to form WTc12 cuboctahedra that share corners with six equivalent WTc12 cuboctahedra, corners with twelve equivalent TcTc8W4 cuboctahedra, edges with eighteen equivalent TcTc8W4 cuboctahedra, faces with eight equivalent WTc12 cuboctahedra, and faces with twelve equivalent TcTc8W4 cuboctahedra. There are six shorter (2.75 Å) and six longer (2.78 Å) W–Tc bond lengths. Tc+1.67- is bonded to four equivalent W5+ and eight equivalent Tc+1.67- atoms to form distorted TcTc8W4 cuboctahedra that share corners with four equivalent WTc12 cuboctahedra, corners with fourteen equivalent TcTc8W4 cuboctahedra, edges with six equivalent WTc12 cuboctahedra, edges with twelve equivalent TcTc8W4 cuboctahedra, faces with four equivalent WTc12 cuboctahedra, and faces with sixteen equivalent TcTc8W4 cuboctahedra. There are a spread of Tc–Tc bond distances ranging from 2.76–2.79 Å.
Tc3Ge is beta Cu3Ti-like structured and crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. Tc+1.33- is bonded to eight equivalent Tc+1.33- and four equivalent Ge4+ atoms to form TcTc8Ge4 cuboctahedra that share corners with four equivalent GeTc12 cuboctahedra, corners with fourteen equivalent TcTc8Ge4 cuboctahedra, edges with six equivalent GeTc12 cuboctahedra, edges with twelve equivalent TcTc8Ge4 cuboctahedra, faces with four equivalent GeTc12 cuboctahedra, and faces with sixteen equivalent TcTc8Ge4 cuboctahedra. There are a spread of Tc–Tc bond distances ranging from 2.69–2.79 Å. There are two shorter (2.72 Å) and two longer (2.74 Å) Tc–Ge bond lengths. Ge4+ is bonded to twelve equivalent Tc+1.33- atoms to form GeTc12 cuboctahedra that share corners with six equivalent GeTc12 cuboctahedra, corners with twelve equivalent TcTc8Ge4 cuboctahedra, edges with eighteen equivalent TcTc8Ge4 cuboctahedra, faces with eight equivalent GeTc12 cuboctahedra, and faces with twelve equivalent TcTc8Ge4 cuboctahedra.
MoTc3 is Uranium Silicide structured and crystallizes in the cubic Pm-3m space group. The structure is three-dimensional. Mo5+ is bonded to twelve equivalent Tc+1.67- atoms to form MoTc12 cuboctahedra that share corners with twelve equivalent MoTc12 cuboctahedra, edges with twenty-four equivalent TcTc8Mo4 cuboctahedra, faces with six equivalent MoTc12 cuboctahedra, and faces with twelve equivalent TcTc8Mo4 cuboctahedra. All Mo–Tc bond lengths are 2.77 Å. Tc+1.67- is bonded to four equivalent Mo5+ and eight equivalent Tc+1.67- atoms to form TcTc8Mo4 cuboctahedra that share corners with twelve equivalent TcTc8Mo4 cuboctahedra, edges with eight equivalent MoTc12 cuboctahedra, edges with sixteen equivalent TcTc8Mo4 cuboctahedra, faces with four equivalent MoTc12 cuboctahedra, and faces with fourteen equivalent TcTc8Mo4 cuboctahedra. All Tc–Tc bond lengths are 2.77 Å.
TcP2H18(C3Br)2 crystallizes in the monoclinic C2/c space group. The structure is zero-dimensional and consists of four TcP2H18(C3Br)2 clusters. there are two inequivalent Tc3- sites. In the first Tc3- site, Tc3- is bonded in a 5-coordinate geometry to one Tc3-, two equivalent P5+, and two equivalent Br1- atoms. The Tc–Tc bond length is 2.19 Å. Both Tc–P bond lengths are 2.46 Å. Both Tc–Br bond lengths are 2.56 Å. In the second Tc3- site, Tc3- is bonded in a 5-coordinate geometry to one Tc3-, two equivalent P5+, and two equivalent Br1- atoms. Both Tc–P bond lengths are 2.46 Å. Both Tc–Br bond lengths are 2.56 Å. There are five inequivalent C+3.83- sites. In the first C+3.83- site, C+3.83- is bonded to one P5+ and three H1+ atoms to form distorted corner-sharing CPH3 tetrahedra. The C–P bond length is 1.83 Å. All C–H bond lengths are 1.10 Å. In the second C+3.83- site, C+3.83- is bonded to one P5+ and three H1+ atoms to form distorted corner-sharing CPH3 tetrahedra. The C–P bond length is 1.82 Å. All C–H bond lengths are 1.10 Å. In the third C+3.83- site, C+3.83- is bonded to one P5+ and three H1+ atoms to form distorted corner-sharing CPH3 tetrahedra. The C–P bond length is 1.83 Å. All C–H bond lengths are 1.10 Å. In the fourth C+3.83- site, C+3.83- is bonded to one P5+ and three H1+ atoms to form distorted corner-sharing CPH3 tetrahedra. The C–P bond length is 1.82 Å. There is one shorter (1.09 Å) and two longer (1.10 Å) C–H bond length. In the fifth C+3.83- site, C+3.83- is bonded to one P5+ and three H1+ atoms to form distorted corner-sharing CPH3 tetrahedra. The C–P bond length is 1.82 Å. All C–H bond lengths are 1.10 Å. There are two inequivalent P5+ sites. In the first P5+ site, P5+ is bonded to one Tc3- and three C+3.83- atoms to form distorted corner-sharing PTcC3 tetrahedra. In the second P5+ site, P5+ is bonded to one Tc3- and three C+3.83- atoms to form distorted corner-sharing PTcC3 tetrahedra. The P–C bond length is 1.83 Å. There are eighteen inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a single-bond geometry to one C+3.83- atom. In the second H1+ site, H1+ is bonded in a single-bond geometry to one C+3.83- atom. In the third H1+ site, H1+ is bonded in a single-bond geometry to one C+3.83- atom. In the fourth H1+ site, H1+ is bonded in a single-bond geometry to one C+3.83- atom. In the fifth H1+ site, H1+ is bonded in a single-bond geometry to one C+3.83- atom. In the sixth H1+ site, H1+ is bonded in a single-bond geometry to one C+3.83- atom. In the seventh H1+ site, H1+ is bonded in a single-bond geometry to one C+3.83- atom. In the eighth H1+ site, H1+ is bonded in a single-bond geometry to one C+3.83- atom. In the ninth H1+ site, H1+ is bonded in a single-bond geometry to one C+3.83- atom. In the tenth H1+ site, H1+ is bonded in a single-bond geometry to one C+3.83- atom. In the eleventh H1+ site, H1+ is bonded in a single-bond geometry to one C+3.83- atom. In the twelfth H1+ site, H1+ is bonded in a single-bond geometry to one C+3.83- atom. In the thirteenth H1+ site, H1+ is bonded in a single-bond geometry to one C+3.83- atom. In the fourteenth H1+ site, H1+ is bonded in a single-bond geometry to one C+3.83- atom. In the fifteenth H1+ site, H1+ is bonded in a single-bond geometry to one C+3.83- atom. In the sixteenth H1+ site, H1+ is bonded in a single-bond geometry to one C+3.83- atom. The H–C bond length is 1.10 Å. In the seventeenth H1+ site, H1+ is bonded in a single-bond geometry to one C+3.83- atom. The H–C bond length is 1.10 Å. In the eighteenth H1+ site, H1+ is bonded in a single-bond geometry to one C+3.83- atom. The H–C bond length is 1.10 Å. There are two inequivalent Br1- sites. In the first Br1- site, Br1- is bonded in a single-bond geometry to one Tc3- atom. In the second Br1- site, Br1- is bonded in a single-bond geometry to one Tc3- atom.
Trapping is commonly used as the primary management tool in attempts to reduce invasive wild pigs (Sus scrofa), but traditional trapping techniques are often ineffective. However, recently developed traps permit the capture of entire social groups (sounders) of wild pigs, and the strategy of whole-sounder removal may achieve more effective control. Our objective was to experimentally compare traditional control (TC; primarily traditional trapping, but including hunting with dogs, and opportunistic shooting) and whole-sounder removal (WSR) strategies by assessing density reduction and removal rate after 1 and 2 years of treatment. After 1 year of trapping, average wild pig density on WSR units declined 53% and remained stable after the second year, whereas on TC units, pig density did not differ after trapping, although it declined 33% and remained stable after the second year of trapping. The median removal rate (percentage of uniquely marked pigs present at the beginning of each year that were removed) was 42.5% for WSR units and 0.0% for TC units during 2018 and were 29.6% from WSR units and 5.3% from TC units during 2019. WSR removal was more effective at reducing wild pig density than TC, but factors such as previous exposure of this population to traditional traps and the lack of barriers to recolonization from surrounding areas may have reduced WSR efficacy. WSR can effectively reduce wild pig density to a greater extent than TC, but managers should recognize the additional time and expense necessary for implementation.
The simultaneous removal of radionuclides technetium-99 and iodine-129 from an actual decontaminated Hanford tank waste sample (a mixture of decontaminated waste from tanks 241-AP-105 and 241-AP-107) was demonstrated for the first time in this work. A series of commercially available ion exchange resins were evaluated in batch contact tests in the tank waste, and all showed removal of both Tc and I. The highest Tc removal was observed for Purolite A530e while the highest iodine removal was observed for ResinTech SIR-110-MP. Batch tests in simulated tank waste with these two resins showed that the SIR-110-HP-MP had consistently higher K d for both pertechnetate and iodide and much higher K d than previous works on Tc removal from Hanford waste. As such, the SIR-110-MP was evaluated in a dual -column (lead/lag) test processing 5.2L of the tank waste mixture showing 60% breakthrough of Tc on the lead column and no significant breakthrough on the lag after 625 bed volumes (BV, 6 mL size) while significant iodine breakthrough (>50%) occurred after 28 BV. The limited iodine uptake was attributed to the column conditions generating mass transfer limitations. A fraction of the Tc and I was not captured by the resin (<10%) in either the batch tests or column tests. The iodine fraction was identified to be an iodide, likely organo-iodide. The fraction of the Tc was identified as a non-pertechnetate species, which is the first time non-pertechnetate has been identified in AP-105 and AP-107 tanks, although the exact species is still unknown.
A growing body of evidence indicates that RNA plays a critical role in orchestrating DNA double-strand break repair (DSBR). Recently, we showed that homologous nascent RNA can be used as a template for error-free repair of double-strand breaks (DSBs) in the transcribed genome and to restore the missing sequence at the break site via the transcription-coupled classical nonhomologous end-joining (TC-NHEJ) pathway. TC-NHEJ is a complex multistep process in which a reverse transcriptase (RT) is essential for synthesizing the DNA strand from template RNA. However, the identity of the RT involved in the TC-NHEJ pathway remained unknown. Here, we report that DNA polymerase eta (Pol η), known to possess RT activity, plays a critical role in TC-NHEJ. We found that Pol η forms a multiprotein complex with RNAP II and other TC-NHEJ factors, while also associating with nascent RNA. Moreover, purified Pol η, along with DSBR proteins PNKP, XRCC4, and Ligase IV can fully repair RNA templated 3'-phosphate-containing gapped DNA substrate. In addition, we demonstrate here that Pol η deficiency leads to accumulation of R-loops and persistent strand breaks in the transcribed genes. Finally, we determined that, in Pol η depleted but not in control cells, TC-NHEJ-mediated repair was severely abrogated when a reporter plasmid containing a DSB with several nucleotide deletion within the E. coli lacZ gene was introduced for repair in lacZ-expressing mammalian cells. Thus, our data strongly suggest that RT activity of Pol η is required in error-free DSBR.
Zero valent iron (ZVI) is a promising material for reductive removal of technetium from industrial waste streams. An example application of this method could be to treatment of low activity aqueous waste that is currently stored in tanks at the Hanford site. However, there is still a lack of understanding of the useful lifetime of ZVI for treatment and the changes in reductive removal of Tc over time. In this research, we studied the reductive removal of Tc from aqueous solutions by ZVI aged with up to 30 days by contact with 0.08 M NaCl solutions. These results show that ZVI could be used to remove Tc(VII) from aqueous solutions by its reduction to the less soluble and relatively immobile Tc(IV) with greater than 99% removal in three hours. Still, greater than 90% of Tc is removed with ZVI aging up to one week. However, after 10 days of aging of zero valent iron, a significant decrease in removal of Tc occurs (55% removal at three hours) followed by negligible removal after aging for two weeks or more which is consistent with formation of iron oxides on the surface. Further, these results correlate with XRD and FTIR analysis showing an increase in magnetite followed by maghemite and goethite with aging time.
Elemental iron Fe 0 is a promising reductant for removal of radioactive technetium-99 (Tc) from complex aqueous waste streams that contain sulfate, halides, and other inorganic anions generated during processing of legacy radioactive waste. The impact of sulfate on the kinetics of oxidation and reduction capacity of Fe 0 in the presence of Tc has not been examined. We investigated the oxidative transformation of Fe 0 and reductive removal of TcO 4 - in 0.1 M Na 2 SO 4 as a function of initial pH (i.e., pH i 4, 7, and 10) under aerobic conditions up to 30 days. Tc reduction was the fastest at pH i 7 and slowest at pHi 10 (Tc reduction rate pHi 7 > 4 > 10). Aqueous fraction of Tc was measured at 0.4% at pH i 7 within 6 h, whereas ≥ 97% of Tc was removed from solutions at pH i of 4 and 10 within 24 h. Solid phase characterization showed that magnetite was the only oxidized crystalline phase for the first 6 h regardless of initial pH. Lepidocrocite was the most abundant oxidized product for pH i 10 after 5 days, but was not observed at pH of 4 or 7.
This work presents an assessment of tropical cyclones (TCs) in the 25 km and 50 km resolution reanalysis-forced and baseline and future (RCP8.5) global climate model (GCM) forced simulations produced for the North American branch of the international Coordinated Regional climate Downscaling Experiment (NA-CORDEX) using the Weather Research and Forecasting (WRF) model. A set of complementary 12 km resolution simulations produced as a part of a different project is also included in this assessment. Before examining the projections from the GCM-driven simulations, the ability of the simulations to minimally produce a realistic spatial distribution of historical TC occurrence was assessed in simulations forced by reanalysis and the three different GCMs used herein. Then, projections for occurrence, TC related mean precipitation and precipitation intensity, storm duration, the intensity measured by minimum pressure and maximum wind speed, storm size, and translation speed were examined. Several of these characteristics show little to no change in the future in trend or in distribution across the ensemble. However, many simulations suggest a westward shift or increase in TC occurrence over the East Pacific basin and a decrease in occurrence over the Caribbean and Gulf of Mexico. Increases (decreases) in total storm-related precipitation are projected where TC occurrence increases (decreases). TC precipitation intensity is found to increase in all simulations over the East Pacific, but projections are mixed over the North Atlantic. Finally, the ensemble projects a distribution shift towards more intense TC over the East Pacific, and a shift toward faster translation speeds over the North Atlantic.
Abstract High‐resolution climate models (∼28 km grid spacing) can permit realistic simulations of tropical cyclones (TCs), thus enabling their investigation in relation to the climate system. On the global scale, previous works have demonstrated that the Community Atmosphere Model (CAM) version 5 presents a reasonable TC climatology under prescribed present‐day (1980–2005) forcing. However, for the Western North Pacific (WNP) region, known biases in simulated TC genesis frequency and location under‐represent the basin's dominant share in observations. This study addresses these model biases in WNP by evaluating WNP TCs in a decadal simulation, and exploring potential improvements through nudging experiments. Among the major environmental controls of TC genesis, the lack of mid‐level moisture is identified as the leading cause of the deficit in simulated WNP TC genesis over the Pacific Warm Pool. Subsequent seasonal experiments explore the effect of constraining the large‐scale environment on TC development by nudging WNP temperature field toward reanalysis at various strengths. Temperature nudging elicits a significant response in TC genesis and intensity development, as well as in moisture and convection over the Warm Pool. These responses are sensitive to the choice of nudging timescale. Overall, the nudging experiments demonstrate that improvements in the large‐scale environment can lead to improvements in simulated TCs, suggesting future model developments in relation to model physics. In this way, the potential improvements in model fidelity will contribute to the understanding of how the mean state of current or future climates may give rise to extremes such as TCs.
This study aims to quantify the impacts of atmosphere–ocean coupling on simulated and projected tropical cyclone (TC) precipitation globally. We used global climate model (GCM) simulations over 1950–2050 from the High Resolution Model Intercomparison Project (HighResMIP) and compared its fully coupled atmosphere–ocean GCMs (AOGCMs) with atmosphere-only GCMs (AGCMs). We find that ocean coupling generally leads to decreased TC precipitation over ocean and land. Large-scale sea surface temperature (SST) biases are critical drivers of the precipitation difference, with secondary contributions from local TC–ocean feedbacks via SST cold wakes. The two driving factors, attributed to ocean coupling in the AOGCMs, influence TC precipitation in association with decreased TC intensity and specific humidity. The AOGCMs and AGCMs consistently project TC precipitation increases in 2015–2050 relative to 1950–2014 over ocean for all basins, and for landfalling TCs in the North Atlantic and western North Pacific.
Abstract This study investigates global tropical cyclone (TC) activity trends from 1990 to 2021, a period marked by largely consistent observational platforms. Several global TC metrics have decreased during this period, with significant decreases in hurricane numbers and Accumulated Cyclone Energy (ACE). Most of this decrease has been driven by significant downward trends in the western North Pacific. Globally, short‐lived named storms, 24‐hr intensification events of ≥50 kt day −1 , and TC‐related damage have increased significantly. The increase in short‐lived named storms is likely due to technological improvements, while rapidly intensifying TC increases may be fueled by higher potential intensity. Damage increases are largely due to increased coastal assets. The significant decrease in hurricane numbers and global ACE are likely due to the trend toward a more La Niña‐like base state from 1990 to 2021, favoring North Atlantic TC activity and suppressing North and South Pacific TC activity.
As a major feature of tropical cyclones (TCs), controlling factors of TC outer size or size scaling remains a fundamental scientific question. The Rossby deformation radius and a natural extent associated with potential intensity have been proposed as two scalings of TC size. But neither of them satisfactorily captures the sensitivity of TC size to sea surface temperature (SST) in idealized f-plane simulations. Inspired by the studies of the Hadley circulation, here we proposed a new TC scaling based on an energetic diagnostic scaling. TC size is primarily a ratio of the secondary circulation strength to subsidence velocity, further determined by the total atmospheric heating in the ascending area, the gross moist stability, the diabatic cooling, and the dry static stability. The former two is based on the moist energetic budget applied to the whole storm structure, while the latter two is based on the dry thermodynamic budget applied to the subsidence areas. The new scaling well captured the sensitivity of TC size to SST in idealized f-plane simulations, partly resulted from expanded ascending area, increased surface moisture deficit, and weakened subsidence with increased SST.
Technetium (Tc) is a very important element that is encountered in many aspects, from its presence in radioactive waste and its potential environmental impact to its use as a medical radioisotope. Its detection and quantification in liquid samples is traditionally cumbersome, involving detailed sample preparation and analysis by mass spectrometry or scintillation. This article demonstrates the first comprehensive emission spectral analysis of Tc from a liquid sample by immobilization in a polymer and analysis by laser-induced breakdown spectroscopy (LIBS). A survey of LIBS spectra was completed to identify the strongest analytical lines for quantification of trace Tc in the presence of Mo. The quantification of Tc in a Mo-containing matrix was selected because Tc radioisotopes are the daughter products of Mo isotope decay. The first reported calibration curves by LIBS are provided with limits of detection and quantification down to 0.710 µg mL −1 and 1.39 µg mL −1 , respectively. Ultimately, this study demonstrated the feasibility of trace Tc quantification using LIBS and will serve as a reference for future research related to monitoring this radioactive species.