Rotation-aligned isomer and oblate collectivity in Pt 196

An oblate rotational sequence, built on an aligned, two-quasineutron isomeric state has been established in Pt196. The isomer has a half-life of 7.7(7) ns and is associated with the Iπ=12+,(i13/2)2 neutron configuration. Excited states, with angular momentum generated primarily through successive nucleon alignments, have been populated through 1p transfer from Au197. The nucleus Pt196 is the most neutron-rich Pt isotope for which high-spin states, beyond the 12+ isomeric state, have been established thus far. Cranked shell model calculations have been performed to understand shape evolution with spin, and the role of nucleons occupying specific Nilsson orbitals in generating aligned angular momentum for both prolate and oblate deformations has been explored

Isomers and oblate rotation in Pt isotopes: Delineating the limit for collectivity at high spins

Rotation-aligned isomeric states and associated oblate collective sequences are established in even Pt isotopes. Reduced E2 transition probabilities for the deexcitation of the 12+ isomers indicate an abrupt and unexpected quenching of oblate collectivity around neutron number N=120. Structure and shape evolution at high spin in the heaviest stable isotopes is found to be markedly different from observations in the lighter ones

Emergence of an island of extreme nuclear isomerism at high excitation near 208Pb

Metastable states with T1/2 = 8(2) ms in 205Bi and T1/2 = 0.22(2) ms in 204Pb, with ≈ 8 MeV excitation energy and angular momentum ≥ 22 ħ, have been established. These represent, by up to two orders of magnitude, the longest-lived nuclear states above an excitation energy of 7 MeV, ever identified in the nuclear chart. Additionally, the half-life of the 10.17 MeV state in 206Bi has been determined to be 0.027(2) ms, the next highest value in this highly excited regime. These observations indicate the emergence of an island of extreme nuclear isomerism arising from core-excited configurations at high excitation in the vicinity of the doubly closed-shell nucleus 208Pb. These results are expected to provide discriminating tests of the effective interactions used in current large-scale shell-model calculations

Isomers in Tl 203 and core excitations built on a five-nucleon-hole structure

Isomers with three- and five-nucleon-hole configurations have been established in Tl203. These include newly identified levels with a three-nucleon-hole structure: Iπ = (15/2-) with T1/2 = 7.9(5) ns and Iπ = (35/2-) with T1/2 = 4.0(5) ns. In addition, five-nucleon-hole states have also been established: Iπ = (39/2-) with T1/2 = 1.9(2) ns and Iπ = (49/2+) with T1/2 = 3.4(4) ns. The previously determined long-lived decay, T1/2 = 6.6(3) μs from this work, is associated with isomerism of the Iπ = (29/2+) state. Levels above this long-lived isomer have been identified through a delayed-prompt γ-γ coincidence measurement. Five-nucleon-hole states with excitation energies Ex≈ 7 MeV have been established as well as possible octupole excitations of the Pb208 core built on these levels. The level scheme of Tl203 is extended up to Ex≈ 11 MeV with the inclusion of 25 new transitions. Empirical and shell-model calculations have been performed to aid in the description of the observed states which are found to be of intrinsic character

Structure of odd- A Pt isotopes along the line of stability

The structure of the odd-A isotopes Pt193,195,197, which lie along the line of stability, has been studied up to high spin through multinucleon transfer reactions. Positive- and negative-parity sequences in Pt193,195 have been considerably extended and multiple band crossings established. An isomer with T1/2=5.0(5) ns and Iπ=25/2- is present in Pt195. The isotopes Pt193,195 are characterized by moderate oblate deformation, and angular momentum generation at high spin in the yrast, positive-parity sequences is attributed to the rotation alignment of i13/2 neutrons and h11/2 protons. A detailed understanding of the observed features is presented using calculations based on tilted axis cranking covariant density functional theory as well as others with the ultimate cranker code

Nanosecond isomers and the evolution of collectivity in stable, even-A Hg isotopes

Isomeric states and associated collective structures have been studied up to high spin in Hg198,200,202 using multinucleon transfer reactions and the Gammasphere array. A coupled rotational band, with possible four-quasiparticle character, is established in Hg198. Sequences built on two-quasiparticle, positive-and negative-parity levels are assigned to Hg202. New isomers in Hg202 with Iπ=(7-) and (9-), and T1/2 = 10.4(4) ns and 1.4(3) ns, respectively, have been identified. A half-life of 1.0(3) ns is established for the Iπ=12+ state in Hg200. B(E2) values deduced from isomeric transitions in Hg isotopes indicate that, while collectivity near the ground state gradually diminishes from N = 112 to N = 124, it is found to increase for the 12+ and 9-states up to N = 118, followed by a reduction for higher neutron numbers. Calculations using the ultimate cranker code provide insight into the variation of deformation with spin and allow for an understanding of observed band crossings. The evolution of collectivity with spin, and along the isotopic chain, is described

Metastable states from multinucleon excitations in Tl 202 and Pb 203

The excited level structures of Tl202 and Pb203, above the 7+ and 29/2- isomers, respectively, have been studied. An isomer with Iπ=20+ and T1/2=215(10)μs has been established in Tl202, and the level scheme extended from I=10 to 20ℏ with the placement of fifteen new transitions. In Pb203, the Iπ=37/2+ state is established to be metastable, with T1/2=2.5(3)ns. Levels in both nuclei arise from intrinsic excitations, with likely particle-hole character for the higher-lying states in Pb203. The 20+ isomer in Tl202 is most likely associated with a πh11/2-1 - ν(i13/2-2,f5/2-1) configuration, while the 37/2+ state in Pb203 results from the excitation of five neutrons. Calculations, using both an empirical approach and the oxbash code, have been performed to aid in the description of the excited level structure

Isomers and oblate rotation in Pt isotopes: Delineating the limit for collectivity at high spins

Rotation-aligned isomeric states and associated oblate collective sequences are established in even Pt isotopes. Reduced E2 transition probabilities for the deexcitation of the 12+ isomers indicate an abrupt and unexpected quenching of oblate collectivity around neutron number N=120. Structure and shape evolution at high spin in the heaviest stable isotopes is found to be markedly different from observations in the lighter ones

Streptomyces pactum addition to contaminated mining soils improved soil quality and enhanced metals phytoextraction by wheat in a green remediation trial

Streptomyces pactum (Act12), an agent of a gentle in situ remediation approach, has been recently used in few works in phytoextraction trials; however, the impact of Act12 on soil quality and metal phytoavailability has not been assessed in multi-metal contaminated soils. Consequently, here we assessed the potential impact of Act12 on the wheat (Triticum aestivum L.) growth, antioxidants activity, and the metal bioavailability in three industrial and mining soils collected from China and contained up to 118, 141, 339, and 6625 mg Cd, Cu, Pb, and Zn kg−1 soil, respectively. The Act12 was applied at 0 (control), 0.75 (Act-0.75), 1.50 (Act-1.5), and 2.25 (Act-2.25) g kg−1 (dry weight base) to the three soils; thereafter, the soils were cultivated with wheat (bio-indicator plant) in a pot experiment. The addition of Act12 (at Act-1.5 and Act-2.25) promoted wheat growth in the three soils and significantly increased the content of Cd, Cu, and Zn in the roots and shoots and Pb only in the roots (up to 121%). The Act12-induced increase in metals uptake by wheat might be attributed to the associated decrease in soil pH and/or the increase of metal chelation and production of indole acetic acid and siderophores. The Act12 significantly decreased the antioxidant activities and lipid peroxidation in wheat, which indicates that Act12 may mitigate metals stress in contaminated soils. Enhancing metals phytoextraction using Act12 is a promising ecofriendly approach for phytoremediation of metal-contaminated mining soils that can be safely utilized with non-edible plants and/or bioenergy crops. © 2021 Elsevier Lt