Pairing effects on the fragment mass distribution of Th,U,Pu,and Cm isotopes

In this article,a comprehensive study of the fission process of Th,U,Pu,and Cm isotopes using a Yukawa-folded meanfield plus standard pairing model is presented.The study focused on analyzing the effects of the pairing interaction on the fragment mass distribution and its dependence on nuclear elongation.The significant role of pairing interactions in the fragment mass distributions of^(230)Th,^(234)U,^(240)Pu,and^(246)Cm was demonstrated.Numerical analysis revealed that increasing the pairing interaction strength decreased the asymmetric fragment mass distribution and increased the symmetric distribution.Furthermore,the odd-even mass differences at symmetric and asymmetric fission points were examined,highlighting their sensitivity to changes in the pairing interaction strength.Systematic analysis of the Th,U,Pu,and Cm isotope fragment mass distributions demonstrated the effectiveness of the model in reproducing the experimental data.In addition,the effects of the zero-point energy and half-width parameter on the fragment mass distribution for^(240)Pu were explored.Thus,this study provides valuable insights into the fission process by emphasizing the importance of pairing interactions and their relationship with nuclear elongation.

Crystal Structure and Mass Spectrometric Fragmentation Behavior of Eprosartan

The crystal structure determination and mass spectrometric fragmentation analysis of the medicinal ingredient eprosartan （4-[2-butyl-5-（2-carboxy-3-thiophen-2-yl-propenyl）-imidazol-l-ylmethyl]-benzoic acid） are presented. The single-crystal X-ray diffraction shows that the colorless transparent crystal of eprosartan is of monoclinic system, space group P2/c with a = 16.1861（15）, b = 10.9813（12）, c = 28.610（3） A, β = 118.452（2）°, Z = 4, V= 4471.1（8） A3, Dc = 1.288 g/cm3,μ（MoKα） = 0.178 mm^-1 and F（000） = 1831. The independent part of the unit cell contains two eprosartan molecules and one unordered H2O molecule in the crystal structure which is fixed by inter- and intramolecular hydrogen bonds. The product ions in electrospray ionization tandem mass spectrometry （ESI-MSn） displays the protonated eprosartan dissociated in three competitive pathways and the fragmentation mechanism is proposed and supported by the FTICRMSn results.

Specific Mass Spectrometric Fragmentations from the Dissociation of Intermediate Ion-Neutral Complexes

It is reported that two kinds of specific mass spectrometric fragmentations are generated from dissociations of the intermediates of both the ion-neutral complex and the proton-bound complex. Collision-induced dissociation, isotopic labelling, and semi-empirical AM1 calculations were used to investigate the formation mechanism of the ion of m/z 139 from ionized tetrahydroimidazole-substituted methylene beta-diketones and the unimolecular fragmentations pathway of 3-phenyl-1-butyn-3-ol upon electron impact.

Fracture behavior and mechanism of highly fragmented steel cylindrical shell under explosive loading

An in-depth understanding of the fracture behavior and mechanism of metallic shells under internal explosive loading can help develop material designs for warheads and regulate the quantity and mass distribution of the fragments formed.This study investigated the fragmentation performance of a new high-carbon silicon-manganese(HCSiMn)steel cylindrical shell through fragment recovery experiments.Compared with the conventional 45Cr steel shell,the number of small mass fragments produced by the HCSi Mn steel shell was significantly increased with a scale parameter of 0.57 g fitted by the Weibull distribution model.The fragmentation process of the HCSi Mn shell exhibited more brittle tensile fracture characteristics,with the microcrack damage zone on the outer surface being the direct cause of its high fragmentation.On the one hand,the doping of alloy elements resulted in grain refinement by forming metallographic structure of tempered sorbite,so that microscopic intergranular fracture reduces the characteristic mass of the fragments;on the other hand,the distribution of alloy carbides can exert a"pinning"effect on the substrate grains,causing more initial cracks to form and propagate along the brittle carbides,further improving the shell fragmentation.Although the killing power radius for light armored vehicles was slightly reduced by about 6%,the dense killing radius of HCSiMn steel projectile against personnel can be significantly increased by about 26%based on theoretical assessment.These results provided an experimental basis for high fragmentation warhead design,and to some extent,revealed the correlation mechanism between metallographic structure and shell fragmentation.

Rapid chemome profiling of Artemisia capillaris Thunb. using direct infusion-mass spectrometry

Background:As one of the most popular traditional Chinese medicines(TCMs)for the treatment of various liver diseases,virgate wormwood herb(Artemisia capillaris Thunb.)has a long application history in TCM practices.It has been well established that the chemical composition is responsible for the pronounced therapeutic spectrum of A.capillaris.Although they are comprehensive,the time-intensive liquid chromatography coupled to tandem mass spectrometry(LCeMS/MS)assays cannot fully satisfy the analytical measurement workload from many test samples.Direct infusion-MS/MS(DIeMS/MS)may be the optimal choice to achieve high-throughput analysis if the mass spectrometer can universally record MS2 spectra.Methods:According to the application of gas phase ion fractionation concept,the MS/MSALL program enables to gain MS2 spectrum for each nominal m/z value with a data-independent acquisition algorithm via segmenting the entire MS1 ion cohort into sequential ion pieces with 1 Da width,when sufficient measurement time is allowed by DI approach.Here,rapid clarification of the chemical composition was attempted for A.capillaris using DIeMS/MSALL.A.capillaris extract was imported directly into the electrospray ionization interface to obtain the MS/MSALL measurement.After the MS1-MS2 dataset was well organized,we focused on structural characterization through retrieving information from the available databases and literature.Results:Twenty-six compounds were found,including 12 caffeoyl quinic acid derivatives,7 flavonoids,and 7 compounds belonging to other chemical families.Among them,24 ones were structurally identified.Compared with the LCeMS/MS technique,DIeMS/MSALL has the advantages of low-costing,solvent-saving,and time-saving.Conclusions:Chemical profiling of A.capillaris extract was accomplished within 5 min by DIeMS/MSALL,and this technique can be an alternative choice for chemical profile characterization of TCMs due to its extraordinary high-throughput advantage.

A Mass Spectrometric Study of Kratom Compounds by Direct Infusion Electrospray Ionization Triple Quadrupole Mass Spectrometry

Mitragynine (MG) and its major metabolites 7-hydroxymitragynine (7-OH-MG) are two of the major components of the plant extract Kratom, which is a tree planted in Southeast Asia. Kratom has long been used by opioid-dependent individuals as an alternative to their unavailable opioid of choice and chronic pain medication, as a stealth-to-urine drug screening opiate substitute while in opioid recovery treatment and recreationally, alone or as a booster. In this study, a direct infusion method was utilized and electrospray ionization triple quadrupole mass spectrometer was used as the detector for data acquisition. Pharmacokinetic study was conducted to investigate the effect of mitragynine and 7-hydroxymitragynine and major fragments of both compounds were proposed.

Pre-neutron fragment mass yields for^(235)U(n,f)and^(239)Pu(n,f)reactions at incident energies from thermal up to 20 MeV

Pre-neutron fragment mass yields in the vicinity of the thermal neutron energy are highly important for applications because of the larger fission cross sections of the^(235)U(n,f)and^(239)Pu(n,f)reactions.In this paper,preneutron fragment mass yields at incident energies from thermal up to 20 MeV are systematically studied using an empirical fission potential(EFP)model,the potential parameters of which are obtained from the measured data.The energy dependences of the peaks and valleys of the pre-neutron fragment mass yields are described by exponential and linear functions for the^(235)U(n,f)and^(239)Pu(n,f)reactions,respectively.The energy dependences of the evaporation neutrons,which play a crucial role in the reasonable description of pre-neutron fragment mass yields,are also obtained from the fission cross sections.The pre-neutron fragment mass yields in this study are not only consistent with the results of previous studies in regions of several Me Vs but also agree well with existing measured data at incident energies from thermal up to 20 MeV.The results show that the feasibility of this EFP model is verified in this extended energy region.

Fission fragment mass yields of Th to Rf even-even nuclei

Fission properties of the actinide nuclei are deduced from theoretical analysis.We investigate potential energy surfaces and fission barriers and predict the fission fragment mass yields of actinide isotopes.The results are compared with experimental data where available.The calculations were performed in the macroscopic-microscopic approximation With the Lublin-Strasbourg Drop(LSD)for the macroscopic part,and the microscopic energy corrections were evaluated in the Yukawa-folded potential.The Fourier nuclear shape parametrization is used to describe the nuclear shape,including the non-axial degree of freedom.The fission fragment mass yields of the nuclei considered are evaluated within a 3D colletive model using the Borm-Oppenheimer approximation.

Systematics on fission fragment mass distribution of neutron induced ^(235)U fission

Based on the neutron induced fission fragment mass distribution data up to neutron energy 20 MeV measured with the double kinetic energy method （KEM） and the radio active method （RAM）, the systematics of fission fragment mass distribution was investigated by using 5 Gaussian model and the systematics parameters were obtained by fitting the experimental data. With the systematics, the yields of any mass A and at any energy in the region from 0 to 20 MeV of neutron energy can be calculated. The calculated results could well reproduce the experimental data measured with KEM, but show some systematical deviation from the data measured by RAM, which reflects some systematical deviations between the two kinds of measured data. The error of systematics yield was calculated in an exact error transformation way, including from the error of the experimental yield data to the error of the discrete parameters, then to the systematics parameters, and at last to the yield calculated with systematics.

Influence of the neck parameter on the fission dynamics within the two-center shell model parametrization

The influence of the neck parameter on the fission dynamics at low excitation energy is studied based on the three-dimensional Langevin approach,in which the nuclear shape is described with the two-center shell model(TCSM)parametrization,and the elongation,mass asymmetry,and fragment deformation are set to be the generalized coordinates of the Langevin equation.We first study the influence of the neck parameter on the scission configuration.We find that there is almost no obvious correlation between the neck parameter and mass asymmetryηat the scission point,indicating that has no evident impact on the fragment mass distribution.The elongation Z_(0)=R_(0) and its correlation with the mass asymmetryηat the scission point are clearly influenced by the neck parameter,which has a strong effect on the total kinetic energy(TKE)distribution of the fragments.The pre-neutron emission fragment mass distributions for 14 MeV n+^(233;235;238)U and^(239)Pu are calculated,and then,based on these results,the post-neutron emission fragment mass distributions are obtained by using the experimental data of prompt neutron emission.The calculated post-neutron emission fragment mass distributions can reproduce the experimental data well.The TKE distributions for 14 MeV n+^(235)U fission are calculated for ε=0.25,0.35,and 0.45,and the results show that the TKE distribution cannot be described very well for the three cases.However,the trend of the calculated TKE distribution withεis just as expected from the scission configuration calculations.The results with ε=0.35 present a better agreement with the experiment data compared with the other two cases.

Study of Cold Fusion Reactions Using Collective Clusterization Approach

Within the framework of the dynamical cluster decay model （DCM）, the in evaporation cross-sections （σ1n） of cold fusion reactions （Pb and Bi targets） are calculated for ZCN = 104-113 superheavy nuclei. The calculations are carried out in the fixed range of excitation energy ECN = 15 ± 1 MeV, so that the comparative analysis of reaction dynamics can be worked out. First of all, the fission barriers （Bf ） and neutron separation energies （S1n） are estimated to account the decreasing cross-sections of cold fusion reactions. In addition to this, the importance of hot optimum orientations of β24-deformed nuclei over cold one is explored at fixed angular momentum and neck-length parameters. The hot optimum orientations support all the target-projectile （t,p） combinations, which are explored experimentally in the cold fusion reactions. Some new target-projectile combinations are also predicted for future exploration. Further, the In cross-sections are addressed for ZCN = 104-113 superheavy nuclei at comparable excitation energies which show the decent agrement with experimental data upto ZCN = 109 nuclei. Finally, to understand the dynamics of higher-Z superheavy nuclei, the cross-sections are also calculated at maximum available energies around the Coulomb barrier and the effect of non-sticking moment of inertia （INS） is also investigated at these energies.