Nuclear Reactions Research Articles

In Silico Born Designed Anti-EGFR Aptamer Gol1 Has Anti-Proliferative Potential for Patient Glioblastoma Cells

The epidermal growth factor receptor (EGFR) is one of the key oncomarkers in glioblastoma (GB) biomedical research. High levels of EGFR expression and mutations have been found in many GB patients, making the EGFR an attractive target for therapeutic treatment. The EGFRvIII mutant is the most studied, it is not found in normal cells and is positively associated with tumor cell aggressiveness and poor patient prognosis, not to mention there is a possibility of it being a tumor stem cell marker. Some anti-EGFR DNA aptamers have already been selected, including the aptamer U2. The goal of this study was to construct a more stable derivative of the aptamer U2, while not ruining its functional potential toward cell cultures from GB patients. A multiloop motif in a putative secondary structure of the aptamer U2 was taken as a key feature to design a novel minimal aptamer, Gol1, using molecular dynamics simulations for predicted 3D models. It turned out that the aptamer Gol1 has a similar putative secondary structure, with G-C base pairs providing its stability. The anti-proliferative activities of the aptamer Gol1 were assessed using patient-derived GB continuous cell cultures, G01 and BU881, with different abundances of EGFR and EGFRvIII. The transcriptome data for the cell culture G01, after aptamer Gol1 treatment, revealed significant changes in gene expression; it induced the transcription of genes associated with neurogenesis and cell differentiation, and it decreased the transcription of genes mediating key nuclear processes. There were significant changes in the gene transcription of key pro-oncogenic signaling pathways mediated by the EGFR. Therefore, the aptamer Gol1 could potentially be an efficient molecule for translation into biomedicine, in order to develop targeted therapy for GB patients.

Appearance of the hindrance to complete fusion in heavy-ion collisions

The small cross-section of the synthesis of the superheavy elements (SHEs) is caused by the hindrance to complete fusion and small survival probability of the compound nucleus against fission. The hindrance to complete fusion is related with such peculiarities of the entrance channel as the mutual orientation angles of the axial symmetry of the colliding deformed nuclei, their mass (charge) asymmetry, the shell effects in their microscopic structure and orbital angular momentum. The appearance of the hindrance to complete fusion has been analyzed in the framework of the dinuclear system (DNS) model by the description of the experimental data obtained in the reactions of the SHE synthesis.

Cross sections of the 226Ra(p,xn) reactions relevant for 225Ac production.

Limited availability constrains the implementation of 225Ac, the most promising α emitter for targeted therapy, in clinical practice. Proton activation of 226Ra is one of few realistic solutions to this problem. We have therefore measured cross sections of relevant 226Ra(p,xn) nuclear reactions in the energy range of 12.0 to 17.2MeV. The obtained results allowed us to deduce the yield of 224Ac, 225Ac, and 226Ac. The consequences of our data to predictions of production capacity and radionuclidic purity of 225Ac are thoroughly discussed, and their comparison with previous measurements and with the prediction of the TALYS 1.96 nuclear reaction model code run with default parameters are provided.

Tetraneutron resonance and its isospin analogues

In this paper, we discuss isospin analogues of the tetraneutron resonance and their possible manifestations in nuclear structure and reactions.

Low-energy incomplete fusion: A systematic study of entrance channel parameters

Research into heavy-ion fusion, a key area of modern nuclear reaction physics, has flourished in recent decades pursuant to developments in accelerator technology. The primary goal of studying heavy-ion reactions is to gain knowledge about the underlying processes and how they are affected by entrance channel parameters, such as beam energy, angular momentum and mass asymmetry. The fusion mechanism of non-[Formula: see text]-cluster projectiles, such [Formula: see text]N and [Formula: see text]F, has been studied in the low-energy zone. It has been challenging to analyze the contributing degrees of freedom in such reactions due to the absence of experimental data. The present study reports the measurement of residual cross-sections from the [Formula: see text]F induced reaction on [Formula: see text]Nb within the energy range of 3–6 MeV/A. The stack foil activation technique followed by offline [Formula: see text] spectroscopy was employed to measure the cross-sections of residues populated in the reaction. The experimental data were compared with theoretical predictions from statistical model code PACE4 to probe the underlying reaction dynamics. The imitation of xn and pxn channel data grossly by model code suggests the production of residues via the complete fusion (CF) mode, while the enhancement observation in [Formula: see text]-channel cross-sections hints at the signatures of incomplete fusion (ICF) in addition to the dominant CF. Thus, the ICF strength fraction ([Formula: see text]) was calculated. Moreover, the estimated incomplete fusion fraction has been used to study the effect of several entrance channel parameters on incomplete fusion reaction dynamics. The present analysis shows the presence of strong clustering in the [Formula: see text]F projectile as [Formula: see text] and [Formula: see text]N.

FRET analysis of the unwrapping of nucleosomal DNA containing a sequence characteristic of the + 1 nucleosome

Sequence-dependent mechanical properties of DNA could play essential roles in nuclear processes by affecting histone-DNA interactions. Previously, we found that the DNA entry site of the first nucleosomes from the transcription start site (+ 1 nucleosome) in budding yeast enriches AA/TT steps, but not the exit site, and the biased presence of AA/TT in the entry site was associated with the transcription levels of yeast genes. Because AA/TT is a rigid dinucleotide step, we considered that AA/TT causes DNA unwrapping. However, our previous MNase-seq experiments with reconstituted nucleosomes left some doubt regarding this interpretation, owing to its high exonuclease activity. Furthermore, MNase cleavage did not provide direct evidence of its structural state. In this study, Förster resonance energy transfer (FRET) measurements were used to investigate salt-induced conformational changes in nucleosomal DNA containing AA/TT repeats at the entry site. We observed that the AA/TT region wrapped around the histone core was as likely as other DNA sequences at physiological salt concentrations. However, it unwrapped at a lower salt concentration, indicating weaker electrostatic interactions with the histone core. Ethidium-induced nucleosome disruption assay showed that the intercalator had greater access to DNA with AA/TT at the entry site. Taken together, these results suggest that AA/TT at the entry sites induces DNA unwrapping from the histone core on the promoter side, which may promote transcriptional activation in response to the approach of transcription-related proteins.

Nuclear interaction correction based on dual-energy computed tomography in carbon-ion radiotherapy.


Accurate dose predictions are crucial to maximizing the benefits of carbon-ion therapy. Carbon beams incident on the human body cause nuclear interactions with tissues, resulting in changes in the constituent nuclides and leading to dose errors that are conventionally corrected using conventional single-energy computed tomography (SECT). Dual-energy computed tomography (DECT) has frequently been used for stopping power estimation in particle therapy and is well suited for correcting nuclear reactions because of its detailed body-tissue elemental information. This study proposes a correction method for the absolute dose in carbon-ion therapy that considers changes in nuclide composition resulting from nuclear reactions with body tissues, as a novel application of DECT.
Approach:
The change in dose associated with nuclear reactions is determined by correcting each integrated depth dose component of the carbon beam using a nuclear interaction correction factor. This factor is determined based on the stopping power, mass density, and nuclear interaction cross-section in body tissue. The stopping power and mass density were calculated using established methods, whereas the nuclear interaction cross-section was newly defined through a conversion equation derived from the effective atomic number.
Main results:
Nuclear interaction correction factors and corrected doses were determined for 85 body tissues with known compositions, comparing them with existing SECT-based methods. The root-mean-square errors of the SECT- and DECT-based nuclear interaction correction factors relative to theoretical values were 0.66% and 0.39%, respectively.
Significance:
This indicates a notable enhancement in the estimation accuracy with DECT. The dose calculations in uniform body tissues derived from SECT showed slight over-correction in adipose and bone tissues, whereas those based on DECT were almost consistent with theoretical values. Our proposed method demonstrates the potential of DECT for enhancing dose calculation accuracy in carbon-ion therapy, complementing its established role in stopping power estimation.&#xD.

Evolutionary tracks, ejecta, and ionizing photons from intermediate-mass to very massive stars with PARSEC

Recent advancements in stellar evolution modeling offer unprecedented accuracy in predicting the evolution and deaths of stars. We present new stellar evolutionary models computed with the updated V2.0 code for a comprehensive and homogeneous grid of metallicities and initial masses. Nuclear reaction networks, mass loss prescriptions, and the treatment of elemental mixing have all been updated in V2.0. We computed models for thirteen initial metallicities spanning Z = to Z = 0.03, with masses ranging from 2.0 to 2000 consisting of a library of over 1,100 (∼ 2100 tracks including pure-He models) full stellar evolution tracks. For each track, the evolution is followed from the pre-main-sequence to the most advanced early-asymptotic-giant-branch or the pre-supernova phases (depending on the stellar mass). Here, we describe the properties of the tracks and their chemical and structural evolution. We computed the final fates and the remnant masses and built the mass spectrum for each metallicity, finding that the combined black hole (BH) pair-instability mass gap spans just between 100 and 130 Moreover, the remnant masses provide models consistent with observed BH masses, such as those from the primaries of GW190521, Cygnus X-1, and Gaia BH3 binary systems. We computed and provided the chemical ejecta from stellar winds and explosive final fates, along with the ionizing photon rates. We show how metallicity affects the evolution, fates, ejecta, and ionizing photon counts from these stars. Our results show strong overall consistency with other tracks computed with different codes, and the most significant discrepancies arise for very massive stars (Mz > 120 due to the different treatment of mixing and mass loss. A comparison with a large sample of observed massive stars in the Tarantula Nebula of the Large Magellanic Cloud shows that our tracks nicely reproduce the majority of stars that lie on the main sequence. All the models are publicly available and can be retrieved in the parsec database.

Nuclear Waste Tank Emission Contributions to Particle Size Distribution.

Pollutants from anthropogenic activities including industrial processes are ubiquitous to the environment. To understand the impact from industrial aerosol on climate and human health, industrial aerosol needs to be better characterized. In this study, particle number concentrations were used as a proxy for atmospheric pollutants, which include both particles and gases. Particle concentration and size distribution were measured using a scanning mobility particle sizer (SMPS) approximately 4.5 km from primary industrial areas at the Savannah River Site in Aiken, SC. Industrial areas include numerous nuclear waste storage and processing tanks. The SMPS data were divided into two groups depending on the wind direction measured onsite to categorize transport from the industrial area or from elsewhere. Industrial contributions were found to have a higher concentration of particles with sizes less than 200 nm, 859 ± 564 cm-3, in comparison to non-industrial attributed particles, 733 ± 495 cm-3 on average from March-July 2021. For sizes larger than 200 nm, industrial and non-industrial particles have a similar concentration, 89 ± 59 cm-3 and 99 ± 61 cm-3, with non-industrial concentrations being slightly larger. To confirm that industrial particles could travel to the sampling location, air dispersion modeling was completed for specific case studies during the sampling period. The atmospheric dispersion modeling results confirmed that particles released at the industrial areas reached the sampling location when the wind direction was favorable for transport from the industrial areas. The greater concentration of smaller-sized particles in industrial emissions has implications for typical particulate measurements (PM2.5), heath impacts, and climatological influences.

Impact of quadrupole and hexadecapole deformations and associated orientations on a variety of asymmetric nuclear reactions

Impact of quadrupole and hexadecapole deformations and associated orientations on a variety of asymmetric nuclear reactions

Nuclear N-WASP Induces Actin Polymerization in the Nucleus with Cortactin as an Essential Factor.

Nuclear actin polymerization was reported to control different nuclear processes, but its regulation is poorly understood. Here, we show that N-WASP can trigger the formation of nuclear N-WASP/F-actin nodules. While a cancer hotspot mutant of N-WASP lacking the VCA domain (V418fs) had a dominant negative function on nuclear F-actin, an even shorter truncation mutant found in melanoma (R128*) strongly promoted nuclear actin polymerization. Nuclear localization of N-WASP was not regulated by the cell cycle and increasing nuclear F-actin formation by N-WASP had no obvious influence on replication. However, nuclear N-WASP/F-actin nodules colocalized partially with RNA Pol II clusters. N-WASP-dependent actin polymerization promoted the maturation of RNA Pol II clusters, with the short truncation mutant R128* unexpectedly showing the strongest effect. Nuclear N-WASP nodules including V418fs colocalized with WIP and cortactin. Importantly, cortactin binding was essential but not sufficient for F-actin formation, while WIP binding was required for actin polymerization by R128*. These data reveal a cortactin-dependent role for N-WASP in the regulation of nuclear F-actin and indicate contrasting nuclear effects for N-WASP mutants found in cancer.

Novel Drug Delivery Particles Can Provide Dual Effects on Cancer "Theranostics" in Boron Neutron Capture Therapy.

Boron (B) neutron capture therapy (BNCT) is a novel non-invasive targeted cancer therapy based on the nuclear capture reaction 10B (n, alpha) 7Li that enables the death of cancer cells without damaging neighboring normal cells. However, the development of clinically approved boron drugs remains challenging. We have previously reported on self-forming nanoparticles for drug delivery consisting of a biodegradable polymer, namely, "AB-type" Lactosome® nanoparticles (AB-Lac particles)- highly loaded with hydrophobic B compounds, namely o-Carborane (Carb) or 1,2-dihexyl-o-Carborane (diC6-Carb), and the latter (diC6-Carb) especially showed the "molecular glue" effect. Here we present in vivo and ex vivo studies with human pancreatic cancer (AsPC-1) cells to find therapeutically optimal formulas and the appropriate treatment conditions for these particles. The biodistribution of the particles was assessed by the tumor/normal tissue ratio (T/N) in terms of tumor/muscle (T/M) and tumor/blood (T/B) ratios using near-infrared fluorescence (NIRF) imaging with indocyanine green (ICG). The in vivo and ex vivo accumulation of B delivered by the injected AB-Lac particles in tumor lesions reached a maximum by 12 h post-injection. Irradiation studies conducted both in vitro and in vivo showed that AB-Lac particles-loaded with either 10B-Carb or 10B-diC6-Carb significantly inhibited the growth of AsPC-1 cancer cells or strongly inhibited their growth, with the latter method being significantly more effective. Surprisingly, a similar in vitro and in vivo irradiation study showed that ICG-labeled AB-Lac particles alone, i.e., without any 10B compounds, also revealed a significant inhibition. Therefore, we expect that our ICG-labeled AB-Lac particles-loaded with 10B compound(s) may be a novel and promising candidate for providing not only NIRF imaging for a practical diagnosis but also the dual therapeutic effects of induced cancer cell death, i.e., "theranostics".

Fano test, clinical proton beams and nuclear reactions

Fano test, clinical proton beams and nuclear reactions

The improved BW model are optimized based on MLP neural network

<sec>The nuclear mass model has significant applications in nuclear physics, astrophysics, and nuclear engineering. The accurately predictions of binding energy are crucial for research on nuclear structure, reactions, and decay. However, traditional mass models exhibit large errors in double magic number regions and heavy nuclei regions. These models struggle to effectively describe shell effects and parity effects in nuclear structures, and also fail to capture the subtle differences observed in experimental results.</sec><sec>This study shows the strong modeling capabilities of MLP neural networks, which optimizes the parameters of the nuclear mass model, and reduces prediction errors in key regions and globally. The neural network takes the features as neutron number, proton number, and binding energy, and the labels as mass-model coefficients. The training set is the multiple sets of calculated nuclear mass model coefficients. Through extensive experimentation, the optimal parameters are determined to ensure model convergence speed and stability. The Adam optimizer is employed to adjust the weights and biases of the network, for reducing the mean squared error loss during training.</sec><sec>The trained neural network model with minimal loss was used to predict the optimal coefficients of the nuclear mass model based on the AME2020 dataset. The optimized BW2 model significantly reduces root-mean-square errors in double magic number and heavy nuclei regions. Specifically, the optimized model achieved reductions of approximately 28%, 12%, and 18% in root-mean-square errors near Z(N) = 50, Z(N) = 50 (82), and Z(N) = 82 (126), respectively. In heavy nuclei regions, the errors were reduced by 48%. The BW3 model, incorporating higher-order symmetry energy terms, reduced global root-mean-square errors from 1.86 MeV to 1.63 MeV after parameter optimization using the neural network.</sec><sec>This work reveals that the model with newly optimized coefficients not only exhibits significant error reductions near double magic numbers but also shows improvements in binding energy predictions for both neutron-rich and neutron-deficient nuclei. Furthermore, the model demonstrates good improvements in describing parity effects, accurately capturing parity-related differences in isotopic chains with varying proton numbers.</sec><sec>This study demonstrates the tremendous potential of MLP neural networks in optimizing nuclear mass model parameters and provides a novel method for optimizing parameters in more complex nuclear mass models. Moreover, the proposed method applies to nuclear mass models with implicit or nonlinear relationships, offering new perspectives for further development of nuclear mass models.</sec>

Modeling shear‐induced flow dynamics in a thermal Riga channel containing radioactive rGO‐magnetite‐mercury in an intense electromagnetic rotational setting

AbstractThe main goal of our study is to examine the shear‐induced flow dynamics of a hybrid nanofluid (HNF) composed of rGO/magnetite‐mercury within a thermal vertical Riga channel in an intense electromagnetic rotational framework, invoking the existence of Hall and ion‐slip currents. The model configuration involves a static right wall and a left wall undergoing either impulsive motion (IM) or accelerated motion (AM), initiating fluid movement, which is mathematically represented by unsteady partial differential equations. The Laplace transform (LT) method is harnessed to get a closed‐form solution for the flow‐regulating equations. Through graphical representations, we detail the dominance of critical parameters on model functions and quantities for both IM and AM scenarios. Our key findings admit that an upswing in rotation and the modified Hartmann number significantly diminishes velocity components in both IM and AM cases. The primary velocity experiences a notable diminution with an amplification in the Hall and ion‐slip parameters, while the secondary velocity's magnitude strengthens. Primary and secondary velocities are consistently higher in IM compared to AM. A heightened modified Hartmann number reduces shear stresses at the moving wall due to primary flow in both IM and AM scenarios. Additionally, the magnitude of shear stresses at the moving wall is consistently more pronounced in IM than in AM, with shear stresses notably higher in IM. As the radiation parameter grows, the rate of heat transfer RHT at both channel walls diminishes. Moreover, rate of heat transfer for the HNF consistently exceeds that for the nanofluid (NF). The novelty of the study lies in its unique combination of a radioactive HNF, the thermal Riga channel, and electromagnetic rotational effects, providing new insights into the flow dynamics under extreme conditions, with potential applications in energy systems, nuclear reactor technology, spacecraft propulsion, satellite operations, space exploration, aerospace engineering, chemical mixing, and materials processing.

Elastic scattering of Lithium induced nuclear reactions

Elastic scattering of Lithium induced nuclear reactions

Effect of single particle potential on total cross section of nuclear reaction

Effect of single particle potential on total cross section of nuclear reaction

Fabrication of thin carbon-backed target of 185Re by evaporation technique and self supporting target of 170Er by cold rolling technique for the study of nuclear reaction dynamics

Fabrication of thin carbon-backed target of 185Re by evaporation technique and self supporting target of 170Er by cold rolling technique for the study of nuclear reaction dynamics

Integral cross section measurement of the 19F( γ, n)18F reaction for 12-20 MeV bremsstrahlung photons.

18F radioactive isotope is widely used in PET imaging for nuclear medicine. Medical linear accelerators producing high-flux bremsstrahlung beams up to 20 MeV are commonly used in radiation therapy. Hence, the production of 18F through photon-induced channels will reduce many of the intricacies in transportation and handling. With this objective, the integral cross sections for 19F(γ, n)18F reaction, for bremsstrahlung endpoint energies of 12, 14.6, and 20 MeV, are measured employing the activation technique. The experimentally measured cross section was analysed using the nuclear reaction code TALYS 1.96. Parameters for level density models and gamma strength function models are optimized within the framework of a statistical approach.

Investigation of Lane-consistent dispersive optical-model potential for <sup>208</sup>Pb

Lead is an important alloy material nuclide. And lead eutectic is also an important coolant, which is applied in the construction of Lead-cooled Fast Reactor such as The European Lead-cooled System (ELSY) and the China Lead-based Research reactor (CLEAR-I), as well as in research related to Generation-IV reactor. The study and calculation of lead nuclear data have important theoretical value and application prospects. <sup>208</sup>Pb is the most stable and abundant isotope in lead nuclei, and high quality description of <sup>208</sup>Pb nuclear scattering data is the key to achieving theoretical calculations of nuclear reaction data for lead nuclei. Based on the dispersive optical model, this work describes nucleon scattering on <sup>208</sup>Pb by using the dispersive optical potential. The dispersive optical model potential is defined by energy-dependent real potentials, imaginary potentials, the corresponding dispersive contributions to the real potential which are calculated analytically from the corresponding imaginary potentials by using a dispersion relation, and isospin dependence is reasonably considered by introducing isovector component (i.e. Lane term) in the potential depth constants of the real Hartree-Fock potential <i>V</i><sub>HF</sub> and the surface imaginary potential <i>W</i><sub>s</sub>. Unlike K-D potential, which requires two different sets of parameters to describe neutron and proton induced scattering data, this optical potential uses the same set of parameters to simultaneously describe nucleon-nucleus scattering data. The derived potential in this work shows a very good description of nucleon-nucleus scattering data on <sup>208</sup>Pb up to 200 MeV. Calculated neutron total cross sections, neutron and proton elastic scattering angular distributions, as well as neutron and proton elastic analyzing powers are shown to be in good agreement with experimental data. Additionally, the difference in potential between the neutron and protons induced is described by the isovector term, a reasonable good prediction of quasielastic (p, n) scattering data is achieved.