Investigation of bound state β− decay half-lives of bare atoms

2021 ◽  
Vol 104 (2) ◽  
Author(s):  
Shuo Liu ◽  
Chao Gao ◽  
Chang Xu
Keyword(s):  
Bound State ◽  
Β Decay

scholarly journals Bound-state double- β decay

2018 ◽  
Vol 98 (6) ◽  
Author(s):  
A. Babič ◽  
D. Štefánik ◽  
M. I. Krivoruchenko ◽  
F. Šimkovic
Keyword(s):  
Bound State ◽  
Β Decay ◽  
Double Β Decay

First observation of bound-state β− decay

1993 ◽  
Vol 553 ◽  
pp. 309-312 ◽  
Author(s):  
M. Jung ◽  
F. Bosch ◽  
K. Beckert ◽  
H. Eickhoff ◽  
H. Folger ◽  
...  
Keyword(s):  
Bound State ◽  
Β Decay

Atomic effects on β-decay

1988 ◽  
Vol 420 (1859) ◽  
pp. 277-321 ◽  
Keyword(s):  
Half Life ◽  
Electronic Configuration ◽  
Bound State ◽  
The Other ◽  
Initial State ◽  
Β Decay ◽  
Point Energy ◽  
Chemical Effects ◽  
Chemically Induced ◽  
Induced Changes

Factors leading to the dependence of the β-decay half-life on the atomic electron environment are discussed. An expression for the rate of allowed β-decay of a nucleus embedded in a multielectron atom having an arbitrary electronic configuration is derived. This is then used to obtain a new expression for the ratio of decay constants for bound and continuum decays from a general electron state. This expression fully incorporates exchange of the β-electron with the other bound electrons. It also includes the inhibition of the decay rate, which originates from the total or partial occupation of orbitals by electrons in the initial state. Specific expressions are presented for bound-state decay of an initial-state atomic system having open or closed s-shell configurations. The magnitudes of chemical effects on low-energy β-decays are demonstrated by calculations on 106 Ru. This isotope appears to represent a particularly favourable case for experimental study of chemical effects. Two main chemical effects are found. One arises from the change in bound-state decays, which, although they constitute a small fraction (less than 1%) of total decays, are very sensitive to chemical effects. The other factor arises from the effect on continuum decays of chemically induced changes in the end-point energy. For 106 Ru both effects lead to changes of order 0.1% in the total decay half-life when the ionicity is changed by one unit. However, both effects tend to partially cancel one another, with the result that the net difference in half-life is in the range 0.01–0.1%.

scholarly journals Bound-state β decay of a neutron in a strong magnetic field

2005 ◽  
Vol 72 (1) ◽  
Author(s):  
Konstantin A. Kouzakov ◽  
Alexander I. Studenikin
Keyword(s):  
Magnetic Field ◽  
Strong Magnetic Field ◽  
Bound State ◽  
Β Decay

Observation of bound-state β− decay of bare 187Re using magnetic analysis

1997 ◽  
Vol 626 (1-2) ◽  
pp. 215-222 ◽  
Author(s):  
E. Wefers ◽  
F. Bosch ◽  
T. Faestermann ◽  
B. Franzke ◽  
J. Friese ◽  
...  
Keyword(s):  
Bound State ◽  
Β Decay ◽  
Magnetic Analysis

CRYO-Electron Microscopy of the Acto-Myosin-ATP Complex

1990 ◽  
Vol 48 (1) ◽  
pp. 248-249
Author(s):  
John Trinickt ◽  
Howard White
Keyword(s):  
Electron Microscopy ◽  
Atp Hydrolysis ◽  
Myosin Head ◽  
Bound State ◽  
Cross Linking ◽  
Weakly Bound ◽  
Cryo Electron Microscopy ◽  
Myosin Subfragment 1 ◽  
Attached State ◽  
High Fraction

The primary force of muscle contraction is thought to involve a change in the myosin head whilst attached to actin, the energy coming from ATP hydrolysis. This change in attached state could either be a conformational change in the head or an alteration in the binding angle made with actin. A considerable amount is known about one bound state, the so-called strongly attached state, which occurs in the presence of ADP or in the absence of nucleotide. In this state, which probably corresponds to the last attached state of the force-producing cycle, the angle between the long axis myosin head and the actin filament is roughly 45°. Details of other attached states before and during power production have been difficult to obtain because, even at very high protein concentration, the complex is almost completely dissociated by ATP. Electron micrographs of the complex in the presence of ATP have therefore been obtained only after chemically cross-linking myosin subfragment-1 (S1) to actin filaments to prevent dissociation. But it is unclear then whether the variability in attachment angle observed is due merely to the cross-link acting as a hinge.We have recently found low ionic-strength conditions under which, without resorting to cross-linking, a high fraction of S1 is bound to actin during steady state ATP hydrolysis. The structure of this complex is being studied by cryo-electron microscopy of hydrated specimens. Most advantages of frozen specimens over ambient temperature methods such as negative staining have already been documented. These include improved preservation and fixation rates and the ability to observe protein directly rather than a surrounding stain envelope. In the present experiments, hydrated specimens have the additional benefit that it is feasible to use protein concentrations roughly two orders of magnitude higher than in conventional specimens, thereby reducing dissociation of weakly bound complexes.

Binding Mechanism and Structural Insights into the Identified Protein Target of Covid-19 with In-Vitro Effective Drug Ivermectin

2020 ◽  
Author(s):  
Parth Sarthi Sen Gupta ◽  
Satyaranjan Biswal ◽  
Saroj Kumar Panda ◽  
Abhik Kumar Ray ◽  
Malay Kumar Rana
Keyword(s):  
Ternary Complex ◽  
Bound State ◽  
Molecular Target ◽  
Cooperative Interaction ◽  
Effective Drug ◽  
Rna Dependent Rna Polymerase ◽  
Protein Target ◽  
Ternary Complex Formation ◽  
Structural Insights

<p>While an FDA approved drug Ivermectin was reported to dramatically reduce the cell line of SARS-CoV-2 by ~5000 folds within 48 hours, the precise mechanism of action and the COVID-19 molecular target involved in interaction with this in-vitro effective drug are unknown yet. Among 12 different COVID-19 targets studied here, the RNA dependent RNA polymerase (RdRp) with RNA and Helicase NCB site show the strongest affinity to Ivermectin amounting -10.4 kcal/mol and -9.6 kcal/mol, respectively. Molecular dynamics of corresponding protein-drug complexes reveals that the drug bound state of RdRp with RNA has better structural stability than the Helicase NCB site, with MM/PBSA free energy of -135.2 kJ/mol, almost twice that of Helicase (-76.6 kJ/mol). The selectivity of Ivermectin to RdRp is triggered by a cooperative interaction of RNA-RdRp by ternary complex formation. Identification of the target and its interaction profile with Ivermectin can lead to more powerful drug designs for COVID-19 and experimental exploration. </p>

Assessment of the volume activity of α-radioactive wastes on surface and specific contamination by portable γ-spectrometry method

2020 ◽  
pp. 468-473
Author(s):  
I. P. Korenkov ◽  
A. I. Ermakov ◽  
A. B. Mayzik ◽  
T. N. Laschenova ◽  
V. N. Klochkov ◽  
...  
Keyword(s):  
Specific Activity ◽  
Experimental Studies ◽  
Germanium Detector ◽  
Low Energy ◽  
Gamma Ray Spectrometry ◽  
Building Structures ◽  
Germanium Detectors ◽  
Volume Activity ◽  
Β Decay ◽  
Γ Spectrometry

The aim of the study is to evaluate the volume activity of radioactive waste (RW) by surface and specific alpha contamination using portable gamma-spectrometry.Materials and methods. Methods of rapid assessment of the content of α-emitting radionuclides in solid waste of various morphologies using gamma-spectrometers based on germanium detectors are considered. Computational methods for determining the effectiveness of radionuclide registration are presented.Results. The possibility of using portable gamma-ray spectrometry to assess the surface and specific activity of various materials contaminated with α-emitters (232Th, 235U, 238U, 237Np, 239Pu, 240Pu and 241Am) is shown. The calculated values of the registration efficiency of low-energy gamma-emitters obtained by modeling the spatial-energy parameters of the detector are given.To simplify the solution of this problem, the calculation program used 20 standard templates of various geometries (rectangular, cylindrical, conical, spherical, etc.). The main sources of error in the survey of contaminated surfaces, largesized equipment and building structures were investigated.Conclusions. The possibilities of portable γ-spectrometry for estimating the volume of RW based on the surface density of contamination of materials with radionuclides of uranium and transuranic elements are investigated. When using γ-spectrometer with a high-purity germanium detector with a range of γ-quanta extended in the low-energy region, radionuclides such as 232Th, 235U,238U, 237Np, 241Am were determined by their own radiation or by the radiation of their daughter products.The “problem” element is plutonium, for rapid evaluation of which it is proposed, in accordance with the radionuclide vector methodology, to use 241Am, which accumulates during the β-decay of 241Pu.According to calculations, the most likely value of the activity ratio 239Pu/241Am for the object where the work was performed (scaling factor) varies in the range from 5.0 to 9.0.Based on the results of calculations and experimental studies, the parameters of the efficiency of registration of various α-emitting radionuclides by portable γ-spectrometers. It has been found that for germanium detectors with an absolute efficiency of registering a point source of 7÷15%, it is n×10–5÷n×10–4%.

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