Semi-empirical formula for spontaneous fission half life time

2010 ◽  
Vol 832 (3-4) ◽  
pp. 220-232 ◽  
Author(s):  
K.P. Santhosh ◽  
R.K. Biju ◽  
Sabina Sahadevan
Keyword(s):  
Empirical Formula ◽  
Half Life ◽  
Spontaneous Fission ◽  
Life Time ◽  
Semi Empirical

Alpha decay and spontaneous fission in superheavy isotopes, Z = 124, using a density-dependent cluster model

2020 ◽  
pp. 2050096
Author(s):  
S. A. Seyyedi
Keyword(s):  
Empirical Formula ◽  
Half Life ◽  
Cluster Model ◽  
Spontaneous Fission ◽  
Alpha Decay ◽  
Nucleon Nucleon ◽  
Empirical Formulas ◽  
Density Dependent ◽  
Double Folding ◽  
Semi Empirical

Alpha decay (AD) and spontaneous fission (SF) half-lives of superheavy nuclei [Formula: see text] have been studied within the density-dependent cluster model. The alpha-nucleus potentials were calculated using the double-folding model with the realistic M3Y nucleon–nucleon interaction. To calculate nuclear half-lives, several semi-empirical formulas were used in addition to the Wentzel–Kramers–Brillouin (WKB) approximation. The calculated AD half-lives agree well with the values computed by the analytical formulas of Royer, the semi-empirical formula of Poenaru et al. and the Viola–Seaborg systematic. To identify the mode of decay of these nuclei, the SF half-lives were calculated using the semi-empirical formula given by Xu et al. The results show that among the isotopes studied, isotopes [Formula: see text] can be survived from the SF and have a half-life greater than [Formula: see text][Formula: see text](s). The study predicts [Formula: see text] chains from isotopes [Formula: see text], [Formula: see text] chains from isotopes [Formula: see text], [Formula: see text] chains from isotopes [Formula: see text] and an AD from [Formula: see text]. These isotopes have a half-life long enough to be synthesized in the laboratory. Also, in the decay chains of these isotopes, it is observed that the nuclei [Formula: see text] have higher half-lives than their neighbors. The neutron numbers corresponding to these isotopes are [Formula: see text] indicating the magical or semi-magical behavior of these numbers, which is in good agreement with the research results.

Examination of α-decay half-lives of undetected transfermium isotopes

2020 ◽  
Vol 29 (10) ◽  
pp. 2050085
Author(s):  
Nguyen Nhu Le ◽  
Nguyen Ngoc Duy
Keyword(s):  
Half Life ◽  
Spontaneous Fission ◽  
Theoretical Calculations ◽  
Q Value ◽  
Calculation Methods ◽  
Α Decay ◽  
Decay Modes ◽  
Predicted Values ◽  
Semi Empirical ◽  
Q Values

This study reports the [Formula: see text]-decay half-lives of 39 transfermium isotopes with [Formula: see text], most of which have not been observed. The half-lives were calculated using micro–macroscopic approaches and semi-empirical formulae, applying current [Formula: see text]-decay Q-values from the latest mass database, AME2016. These results were compared to predicted values in previous works to evaluate the efficiency of and difference between various calculation methods. We found that the [Formula: see text]-resonance approach used in a previous study is not appropriate to predict though most other approaches are mutually consistent. An uncertainty of 70% was observed in the present theoretical calculations, similar to that observed in measurements. A Q-value uncertainty of 10% can lead to a large variation of 3 orders of magnitude in predicted [Formula: see text]-decay half-life. We also found that the dominance of either [Formula: see text] decay or spontaneous fission is unclear for the isotopes with [Formula: see text]–[Formula: see text], whereas most of the nuclei of [Formula: see text]–[Formula: see text] can be clearly identified as [Formula: see text] emitters. Finally, we provide the updated [Formula: see text]-decay half-lives for the isotopes of interest, including their uncertainties and corresponding decay modes.

Covalent Complexes Between Low Molecular Weight Heparin Fragments and Antithrombin III – Inhibition Kinetics and Turnover Parameters

1983 ◽  
Vol 49 (02) ◽  
pp. 109-115 ◽  
Author(s):  
M Hoylaerts ◽  
E Holmer ◽  
M de Mol ◽  
D Collen
Keyword(s):  
Molecular Weight ◽  
Half Life ◽  
Low Molecular Weight Heparin ◽  
Antithrombin Iii ◽  
Factor Xa ◽  
Life Time ◽  
Low Molecular Weight ◽  
High Affinity ◽  
Plasma Half Life ◽  
Covalent Complex

SummaryTwo high affinity heparin fragments (A/r 4,300 and M, 3,200) were covalently coupled to antithrombin III (J. Biol. Chem. 1982; 257: 3401-3408) with an apparent 1:1 stoichiometry and a 30-35% yield.The purified covalent complexes inhibited factor Xa with second order rate constants very similar to those obtained for antithrombin III saturated with these heparin fragments and to that obtained for the covalent complex between antithrombin III and native high affinity heparin.The disappearance rates from plasma in rabbits of both low molecular weight heparin fragments and their complexes could adequately be represented by two-compartment mammillary models. The plasma half-life (t'/j) of both low Afr-heparin fragments was approximately 2.4 hr. Covalent coupling of the fragments to antithrombin III increased this half-life about 3.5 fold (t1/2 ≃ 7.7 hr), approaching that of free antithrombin III (t1/2 ≃ 11 ± 0.4 hr) and resulting in a 30fold longer life time of factor Xa inhibitory activity in plasma as compared to that of free intact heparin (t1/2 ≃ 0.25 ± 0.04 hr).

Simultaneous optimization of activity and stability of xylose reductase from D. nepalensis NCYC 3413 using statistical experimental design

2020 ◽  
Vol 27 ◽  
Author(s):  
Shwethashree Malla ◽  
Sathyanarayana N. Gummadi
Keyword(s):  
Half Life ◽  
Specific Activity ◽  
Enzyme Stability ◽  
Reductase Activity ◽  
Xylose Reductase ◽  
Life Time ◽  
Economic Feasibility ◽  
Simultaneous Optimization ◽  
Physical Parameters ◽  
Statistical Experimental Design

Background: Physical parameters like pH and temperature play a major role in the design of an industrial enzymatic process. Enzyme stability and activity are greatly influenced by these parameters; hence optimization and control of these parameters becomes a key point in determining the economic feasibility of the process. Objective: This study was taken up with the objective to optimize physical parameters for maximum stability and activity of xylose reductase from D. nepalensis NCYC 3413 through separate and simultaneous optimization studies and comparison thereof. Method: Effects of pH and temperature on the activity and stability of xylose reductase from Debaryomyces nepalensis NCYC 3413 were investigated by enzyme assays and independent variables were optimised using surface response methodology. Enzyme activity and stability were optimised separately and concurrently to decipher the appropriate conditions. Results: Optimized conditions of pH and temperature for xylose reductase activity were determined to be 7.1 and 27 ℃ respectively, with predicted responses of specific activity (72.3 U/mg) and half-life time (566 min). The experimental values (specific activity 50.2 U/mg, half-life time 818 min) were on par with predicted values indicating the significance of the model. Conclusion: Simultaneous optimization of xylose reductase activity and stability using statistical methods is effective as compared to optimisation of the parameters separately.

Radical Intermediates in Photochemical and Redox Initiated Decomposition of Thioazo Compounds(an EPR and Cyclovoltammetric Study)

1997 ◽  
Vol 62 (6) ◽  
pp. 855-865 ◽  
Author(s):  
Katarína Erentová ◽  
Vladimír Adamčík ◽  
Andrej Staško ◽  
Oskar Nuyken ◽  
Arming Lang ◽  
...  
Keyword(s):  
Decomposition Rate ◽  
Half Life ◽  
Spin Trap ◽  
Solvent Molecule ◽  
Life Time ◽  
Radical Intermediates ◽  
Reactive Radicals ◽  
Induced Decomposition

The cathodically and photochemically induced decomposition of thioazo compounds XC6H4-N2-S-C6H4CH3 and their polymers with X = NO2, COOH, and SO3H were investigated. The formation of carbon-centered XC6H4. and sulfur-centered .S-C6H4Y radicals was confirmed using spin-trap technique. These reactive radicals either abstract hydrogen from CH3CN solvent molecule forming .CH2CN radical or they recombine to cage products XC6H4-S-C6H4CH3 eliminating N2. The decomposition rate of the investigated thioazo compounds is characterized by a formal half-life time of 5 to 10 s.

scholarly journals Grasses and legumes as cover crop in no-tillage system in northeastern Pará Brazil

2014 ◽  
Vol 44 (4) ◽  
pp. 411-418 ◽  
Author(s):  
Renato Alves Teixeira ◽  
Tatiana Gazel Soares ◽  
Antonio Rodrigues Fernandes ◽  
Anderson Martins de Souza Braz
Keyword(s):  
Half Life ◽  
Dry Matter ◽  
C:N Ratio ◽  
Life Time ◽  
Dry Matter Production ◽  
Agricultural Systems ◽  
Climate Conditions ◽  
Jack Bean ◽  
No Till ◽  
Matter Production

Studies to select one or more species of coverage plants adapted to Amazonian soil and climate conditions of the Amazon are a promising strategy for the improvement of environmental quality, establishing no-till agricultural systems, and thereby reducing the impacts of monoculture farming. The aim of this study was to assess the persistence time, half-life time, macronutrient content and accumulation, and C:N ratio of straw coverage in a Ultisol in northeastern Pará. Experimental design was randomized blocks with five treatments and five replicates. Plants were harvested after 105 days, growth and biomass production was quantified. After 84 days, soil coverage was 97, 85, 52, 50, and 15% for signalgrass (Brachiaria brizantha) (syn. Urochloa), dense crowngrass (Panicum purpurascens), jack bean (Canavalia ensiformes), pearl millet (Pennisetum americanum) and sunn hemp (Crotalaria juncea,), respectively. Signalgrass yielded the greatest dry matter production (9,696 kg ha-1). It also had high C:N ratio (38.4), long half-life (86.5 days) and a high persistence in the field. Jack bean also showed high dry matter production (8,950 kg ha-1), but it had low C:N ratio (17.4) and lower half-life time (39 days) than the grasses. These attributes indicate that signalgrass and jack bean have a high potential for use as cover plants in no-till agricultural systems in the State of Pará.

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