Total Cross Sections Research Articles

The astrophysical [formula omitted] factor of [formula omitted]9Be radiative capture reaction in a potential model

In this work, we calculate the S-factor for p+9Be Radiative Capture Reaction according to a modified potential model. We consider the sum of all possible electrical and magnetic transitions as a total cross-section. The zero-energy S-factor results are in good agreement with previously theoretical studies and the experimentally reported data.

Uniformity of neutron absorber distribution in Gd-containing neutron absorber materials

For neutron absorber materials (NAMs), it is important to evaluate their neutron-absorption capability and quantitatively evaluate the uniformity of the distribution of neutron-absorbing elements within the materials. In this study, neutron attenuation testing with cold neutrons was conducted on Ti-based model alloys with Gd concentrations ranging from 1 to 10 wt%. The neutron attenuation coefficients (μ) of the Ti-Gd alloys were determined and compared with the total macroscopic cross sections (Σt), which were computed using the latest ENDF/B library. Although the measured μ increases with the Gd-content, the coefficients were not linearly proportional to the absorber amount, and the ratio of μ to Σt gradually decreased. This was caused by beam hardening, which is more significant for higher-absorbing and thicker NAMs. To examine the uniformity of the neutron absorbers (NAs) in plates, we propose a method for characterizing the degree of homogeneity by introducing a radial distribution function (RDF). After the optical microscopic images of the Ti-Gd alloys were converted to grayscale, the RDF of the Gd particles in the alloys was calculated under the assumption that a large particle is composed of many adjacent unit particles. A unit particle was regarded as one pixel in the digital image. For all Ti-Gd alloys, the RDF had a value of > 1 at short interparticle distances, which indicated a dense population of particles in a small area due to cluster formation. The method of using the RDF as a uniformity parameter was validated through a case study involving a fixed NA content with different distributions.

Single Electron Capture in Collisions of Fast Ions with Molecular Hydrogen in the Impact Parameter Representation

A theoretical method for evaluating the single-electron capture (SEC) cross sections in collisions of fast ions with a ground-state H2molecule is presented. The scattering problem for ion-molecule collisions is formulated in the impact parameter representation using the relation between the quantum-mechanical amplitude and quasi-classical impact parameter one. The capture amplitudes and corresponding probabilities of capture to (nlm) states of an incident ion are derived within the framework of the Brinkman–Kramers approximation. The general expressions for the SEC probability amplitudes ton-states, summed overlandmquantum numbers, are deduced, from which the corresponding SEC probabilities can be then calculated using a procedure of multichannel normalization. The dependence of the differential cross sections, integrated over projectile impact parameters, on the molecular orientation for charge exchange in H++ H2collisions is considered and compared with measurements and other calculations. Total SEC cross sections, integrated over the molecular orientations and summed overn-states for several bare and dressed ions, are calculated and compared with available experimental data and results of calculations by means of other theoretical methods.

Verification of T Invariance in the Total Interaction Cross Section of Neutrons with Unpolarized Nuclei Using the Polarization–Asymmetry Theorem

To date, the violation of T invariance (TI) has been experimentally established for the decays [J.H.Christenson et al., Phys. Rev. Lett.13, 138 (1964)] and oscillations [A. Angelopoulos et al., Phys. Lett. B444, 43 (1998)] of neutral kaons. Phenomenologically, TI violation in the system of neutral kaons is associated with the difference of the Kobayashi–Maskawa phase from zero (or from π) in the standard model of the electroweak interaction. For nucleon–nucleus interactions, this phase turns out to be very small [P.Herszeg, inSymmetries and Fundamental Interactions in Nuclei, World Scientific, Singapore (1995), p.89)]. Estimates of the nucleon–nucleon matrix element corresponding to TI violation in various models are given in [V. Gudkov, inFundamental Physics with Pulsed Neutron Beams, World Scientific, Singapore (2001), p. 117]. All these estimates are small and have a large spread. Therefore, the verification of TI in nuclear processes actually means a search for other mechanisms for its violation. Below is a description of the experimental methods for TI verification in the total interaction cross sections of low-energy resonance neutrons with unpolarized nuclei with the use of the polarization–asymmetry (PA) theorem.

Quantum-mechanical four-body versus semi-classical three-body theories for double charge exchange in collisions of fast alpha particles with helium targets

AbstractWithin the two-channel distorted wave second-order perturbative theoretical formalism, we study capture of both electrons from helium-like targets by heavy nuclei as projectiles at intermediate and high impact energies. The emphasis is on the four-body single-double scattering (SDS-4B) method and the three-body continuum distorted wave impact parameter method (CDW-3B-IPM). The SDS-4B method deals with the full quantum-mechanical correlative dynamics of all the four interactively participating particles (two electrons, two nuclei). The CDW-3B-IPM is a semi-classical three-body independent particle model (one electron, two nuclei), using a combinatorial calculus to describe double capture by a product of two uncorrelated probabilities, integrated over impact parameters. Both theories share a common feature in having altogether two electronic full Coulomb continuum wave functions. One such function is centered on the projectile nucleus in the entrance channel, whereas the other is centered on the target nucleus in the exit channel. These two methods satisfy the correct initial and final Coulomb boundary conditions in the asymptotic region of scattering, at infinitely large inter-particle separations. Yet, it is presently demonstrated that most of the available experimental data on total cross sections for the double capture from helium by alpha particles distinctly favor the SDS-4B method. This is especially true at intermediate energies. Such energies are critically important in versatile applications under the general umbrella of ion transport in matter, including thermonuclear fusion (plasma physics) and ion therapy (medicine).

Effect of T-Invariance Violation in Scattering of Polarized 3He Nuclei on Tensor-Polarized Deuterons

In the interaction of a transversely polarized nuclear beam with a tensor-polarized deuteron target, a nonzero value of the component of the total cross section corresponding to this combination of polarizations is an unambiguous signal ofT-invariance violation whileP-parity is preserved. The method developed earlier for calculating this component of the total cross section forpdscattering based on the Glauber theory has been generalized by us to the case of3Hedscattering, and its energy dependence in the range of beam energies 0.1–1 GeV/nucleon has been calculated. It is found that in3Hedcollisions, in contrast topdscattering, the contribution of only one type ofT-violating nucleon-nucleon forces dominates, which is essential for extraction of the unknown constant of this interaction from the corresponding data.

Electron-induced ionization cross-sections for C5H5N

The secondary electron energy-dependent partial differential ionization cross sections at fixed incident electron energies 100 and 200 eV and their integral or total ionization cross sections in the incident electron energy range ionization threshold to 5 keV for C5H5N Bio-molecule due to electron impact corresponding to the produced major cations are calculated by employing revisited Jain-Khare semiempirical approach. The averaged secondary electron energy and the ionization rate coefficients are calculated from the ionization threshold to 5 keV. The present results are compared with available experimental and theoretical results and are found to be in satisfactory agreement.

Global density-dependent α–nucleon interaction for α–nucleus elastic scattering

Abstract We provide a global density-dependent 4He–nucleon (DD-αN) interaction to construct the α–nucleus optical model potential (OMP) across a wide range of incident energies. The global parametrization for the DD-αN interaction is obtained based on the proton–4He OMP, which reproduces the elastic scattering cross-section data very well in the incident energies of 12.04–500 MeV per nucleon. Using the present DD-αN interaction, we derive the α–nucleus potential by a folding procedure with the point-nucleon density obtained by a microscopic mean-field model. The density dependence of the DD-αN interaction is fixed phenomenologically to reproduce the α–nucleus elastic scattering cross-section data obtained from 16O, 40Ca, 58Ni, 90Zr, and 208Pb targets at E/A = 10–342.5 MeV. We also show the total reaction cross sections, which are helpful in fixing one free parameter, the renormalization factor for the imaginary part of the α–nucleus potential. Lastly, we show some examples, which clearly demonstrate the validity and power of the present DD-αN approach.

Re-utilization of long lived 99Tc radio isotope via Photon induced nuclear reactions

Technetium-99 is a radioactive waste produced primarily in nuclear reactors. It is also left as radioactive waste in hospitals, directly from 99mTc isomeric state. To bring down the quantity of technetium-99 radioactive waste, the nuclear reactions using photon beam is explored. The integral cross section of the reaction 99Tc(γ,γ′)99mTc has been determined using the photo-nuclear activation method. The experiment was done using bremsstrahlung photons having endpoint energies viz. 6, 9, 12, 16, and 20 MeV. 115In(γ,γ′)115mIn reaction has been used as a monitor reaction, for the flux normalization of the bremsstrahlung spectrum. Theoretical model calculations have been done using the nuclear reaction code Talys 1.9. Theoretical parameter values are optimized with the presently obtained data. Total cross sections are estimated and investigated the feasibility of re-utilization of the technetium-99 radioactive isotope.

Development and evaluation of boron carbide-modified unsaturated polyester resin for use as neutron radiation Protection

Neutrons are electrically neutral particles that can penetrate through various materials and interact with atomic nuclei. Neutrons can emit radiation with varying degrees of energy, which can be harmful to both living organisms and the environment. The objective of this study is to evaluate the thermal neutron (0.025 eV) shielding properties of unsaturated polyester resin with boron carbide content ranging from 0 to 20 wt% for use as neutron shielding materials. The FLUKA Monte Carlo simulation was utilized to evaluate the interactions between thermal neutrons and materials with a thickness of 5 cm. The total cross-section, mean free path, and half-value thickness were calculated to assess the shielding properties of materials. The results indicated that as the boron carbide content increased, the total cross-section increased while the mean free path and half-value thickness decreased. In addition, the polyester resin with 20 wt% of boron carbide exhibited the best properties for shielding thermal neutrons. Thus, this study suggests that unsaturated polyester resin containing boron carbide can be used as an effective material for shielding thermal neutrons.

NUCLEAR STRUCTURE STUDY OF THE HALO NUCLEI

The existence of halo nuclei is one of the major important discoveries in the field of nuclear physics. These nuclei are treated as loosely bound system in which a core of normal nuclear density is surrounded by so-called neutron (or proton) halo of diluted nuclear matter. Many theoretical investigations have attempted to understand these nuclei, which exist at light to heavy masses. The phenomenon of nuclear halo is a quantum effect that occurs in nuclei due to the presence of valence nucleons with low separation energy and I = 0, 1 (low angular momentum), and is manifested by the extraordinarily large radii of these nuclei. The core plus halo model is commonly used to describe halo nuclei. This model recognizes the need to treat the core and the halo neutrons or protons separately. By considering different model spaces for the core and the halo nucleons, we can better explain the properties of halo nuclei. This separation is justified by the fact that the valence nucleons in a halo nucleus have different properties compared to the core. Halo nuclei at rest cannot be used as target due to their short-lived species and extraordinary ratio of neutrons and protons (either neutron-rich or proton-rich). Instead, they can be studied through direct reactions with a radioactive isotope beam, employing inverse kinematics where the role of the beam and target are exchanged. In order to investigate the charge and matter densities of these nuclei, total and differential reaction cross section analyses of proton scattering on halo nuclei have been carried out using various theoretical and phenomenological methods

L-MM Auger electron emission from chlorinated organic molecules under proton impact: Angular distribution and total cross section measurement

We have measured the absolute cross section for L-MM Auger electron emission in chlorinated methanes and benzene chloride molecules in collision with keV energy protons. The measurements have been performed with four different chlorine containing organic molecules viz CCl4, CHCl3, CH2Cl2 and C6H5Cl. We have measured the angular distribution of chlorine L-MM Auger electrons at backward emission angles (90° – 150°). The angular distribution shows an isotropic character. We also studied the projectile energy dependence of the total L-MM Auger yield for proton energy ranging from 125 keV to 275 keV. Carbon K-LL Auger yield was also obtained in the same experiments.

Atomic structure calculations, and electron impact ionization cross-sections of W LXI

The present study provides a wide range of calculations of atomic structure data for the tungsten ion W LXI, that belongs to the silicon isoelectronic sequence. The fully relativistic Multi-configuration Dira-Hartree–Fock (MCDHF) method including configuration interaction (CI) is applied to the current ion. Calculated results of energy levels, oscillator strengths, and radiative rates of W LXI are presented. A set of two configuration state lists including the configurations of 3s23p2, 3s3p3, 3s23p3d, and 3p4 at different angular momenta (J) and parity (P) are considered in the configuration interaction calculations of level energies and oscillator strengths. To increase the accuracy of the results, the electronic correlations from higher orbitals, i.e., 7l orbitals are included in the calculations. Quantum electrodynamics effects such as vacuum polarization and self-energy are recalled in the CI calculations. Many more transitions in the soft x-ray region (between 20 and 200 angstroms) have been identified. The flexible atomic code package has been used to compute the electron impact ionization cross-sections of 3s23p2 3P0,1, 1D2 levels in silicon-like tungsten. The cross-sections of the transitions from the ground level in W LXI to the first levels in the 61st ionization of tungsten have been computed using FAC code. The total ionization cross-sections of the 3s23p2 at electron energy range from 5–35 keV are evaluated as well.

Holographic description of elastic photon-proton and photon-photon scattering

We investigate the elastic photon-proton and photon-photon scattering in a holographic QCD model, focusing on the Regge regime. Considering contributions of the Pomeron and Reggeon exchange, the total and differential cross sections are calculated. While our model involves several parameters, by virtue of the universality of the Pomeron and Reggeon, for most of them the values determined in the preceding study on the proton-proton and proton-antiproton scattering can be employed. Once the two adjustable parameters, the Pomeron-photon and Reggeon-photon coupling constant, are determined with the experimental data of the total cross sections, predicting the both cross sections in a wide kinematic region, from the GeV to TeV scale, becomes possible. We show that the total cross section data can be well described within the model, and our predictions for the photon-proton differential cross section are consistent with the data.

Age-related changes in the microstructural organization of the human posterior associative cortex from birth to age 12 years

BACKGROUND: Human posterior associative cortex, including its temporoparietal–occipital subarea, is important in cognitive control, verbal activity, sensory stimuli processing, and attention regulation, visuomotor responses, and situational decision making. Despite data suggesting the prolonged formation of these higher mental functions during postnatal ontogeny, the posterior associative cortex has been insufficiently characterized with respect to microstructural transformations in its individual functionally specialized zones during childhood development.
 AIM: This study aimed to examine age-related changes in the cytoarchitecture of functionally differentiated zones of the posterior associative cortex in the temporal and occipital lobes of the cerebral hemispheres from birth to 12 years of age.
 MATERIALS AND METHODS: The study analyzed 73 left cerebral hemispheres of male children from birth to age 12 years who died because of an accident. Computerized morphometry was employed to measure cortical thickness, outer pyramidal plate thickness, and pyramidal neuron profile field area on Nissl-stained paraffin sections of the cortex taken in the temporoparietal–occipital subarea (subareas 37ac, 37a, and 37d) and area 19 of the occipital region. Quantitative data were analyzed at annual intervals.
 RESULTS: The thickness of the posterior associative cortex increased on the lateral surface of the temporal and occipital lobes at the ages of 1, 4, and 7 years; on the inferior medial surface of the temporal lobe at the ages of 1 and 6 years; and on its medial surface at the ages of 1 and 7 years. The layer III thickness in subareas 37ac, 37a, and 37d significantly increased synchronously with the increase in cortical cross-sectional area, and in area 19, it continued from the age of 4 to 7 years after the stabilization of the group-average indicators of cortical thickness in this field. All areas examined were characterized by a two-step growth of cortical thickness, which exceeded the growth rate of layer III thickness in relation to the total cortical cross-section. The size of the pyramidal neurons in subareas 37ac and 37d increased in two stages, whereas those in subarea 37a and area 19 increased in three stages of different durations.
 CONCLUSIONS: Microstructural changes in the posterior associative cortex in children are heterochronic, heterodynamic, and specialized not only in topographically and functionally distinct cortical areas but also in separate cytoarchitectonic fields, subfields, and level of cytoarchitectonic layers and intracortical microstructural components. The most significant morphofunctional transformations are observed during the first year of life and at the ages of 3–4, 6–7, and 10 years.

Ionization of CH[formula omitted] under fast He-like Si-ion impact

We have studied the absolute double differential cross section (DDCS) of electrons ejected from the methane molecule (CH4) under the impact of highly charged fast projectile ions. The energy and angular distributions of electrons have been measured in interactions with 70 MeV Si12+ ions. These DDCS data together with the derived single differential cross sections and the total cross section (TCS) have been compared with predictions of the continuum distorted wave-eikonal initial state model using different approaches for the molecular orbitals. It has been found that the theories overestimate the measured DDCS values at low ejection energies, which may indicate shortcomings of the model in the case of strong perturbation. At the same time, applying the model to a previous measurement using fast C ions having a lower perturbation strength, excellent agreements have been obtained with the experimental data. Considering the scaling properties, the available TCS data have been plotted with a scaled parameter, namely the perturbation strength, q/v (where q= charge state, v=velocity of the projectile). The KLL Auger e-emission as well as the KLL hyper-satellite peaks are analyzed for different emission angles. The double K-vacancy production shows a considerable enhancement i.e. 37% of the single production cross section which is consistent with some of the recent experiments on K-ionization using x-ray techniques.

Aromatic hydrocarbons as Molecular Propellants for Electric Propulsion Thrusters

The aromatic hydrocarbons (AHs) fluorobenzene, naphthalene, and 1-fluoronaphthalene are introduced as promising alternatives to xenon as propellant for in-space electric propulsion (EP). These storable molecules have similar mass, lower cost, and lower ionization energies compared to xenon, as well as the critical advantage of low post-ionization fragmentation compared to other molecular propellant candidates. The ionization characteristics of AHs are compared with those of xenon and the diamondoid adamantane, previously evaluated as a molecular propellant for EP. Quantum chemical calculations and BEB theory together with 25 eV electron ionization mass spectrometry (EI-MS) measurements have been used to predict the fragmentation of the AHs and adamantane when ionized in a plasma with an electron temperature of 7 eV (a typical electron temperature in EP plasmas). A high fraction (81 − 86%) of the detected AH ions originate from intact molecules, compared to 34% for adamantane, indicating extraordinarily low fragmentation for the selected AHs. The ionization potential of the AHs is similar to that of adamantane but lower compared to xenon (8.14–9.2 eV for the AHs, 9.25 for adamantane and 12.13 eV for xenon). BEB calculations have also been used to predict total ionization cross sections. The calculated ionization cross section of the AHs is comparable to that of adamantane but 3–5 times higher than that of xenon, which together with the low ionization potential can contribute to more efficient ionization. The AHs may have the potential to perform better than xenon, despite the absence of fragmentation in xenon.

Accurate Ab Initio Investigation of Electronic and Radiative Properties, and Cross Sections for Charged Diatomic Systems FrLi+ and FrNa.

This paper presents an extensive ab initio investigation of the electronic properties and elastic collisions of charged diatomic systems FrLi+ and FrNa+. We employ an accurate ab initio approach using nonempirical pseudopotentials for Li+, Na+, and Fr+ cores. We calculate the potential energy curves of the ground state and low-lying excited states of 2Σ+, 2Π, and 2Δ symmetries, identifying and interpreting avoided crossings between higher 2Σ+ and 2Π states. The spectroscopic parameters, transition dipole moments, and vibrational energies associated with 1-32Σ+ states are calculated, along with the radiative lifetimes of the vibrational states trapped in the 22Σ+ state. Using accurate potential energy data, we evaluate partial and total cross sections across a wide range of energies. At low energies (<1 mK), the elastic cross section follows the Wigner law threshold comportment, while at high energies, it scales as E-1/3. To the best of our knowledge, no theoretical or experimental data have been collected on these charged diatomic systems until now. Hence, we proceeded to analyze our findings by comparing them with data acquired from comparable systems. The information pertaining to electronic structures, spectroscopic parameters, transition properties, and collision data provided in this work is expected to serve as a valuable guideline for future theoretical and experimental research on each considered system.

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The production of the 180mHf\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$^{180\ extrm{m}}\ extrm{Hf}$$\\end{document} nuclei in the photoproton reaction 181Ta(γ,p)\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${^{181}\ extrm{Ta}}(\\gamma ,p)$$\\end{document} was studied at end-point bremsstrahlung energies Eγmax=35\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$E_{\\mathrm{\\gamma max}}=35$$\\end{document}–95 MeV. The experiment was performed at the electron linear accelerator LUE-40 NSC KIPT with the use of the γ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\gamma $$\\end{document} activation and off-line γ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\gamma $$\\end{document}-ray spectroscopy. The experimental values of the bremsstrahlung flux-averaged cross-sections ⟨σ(Eγmax)⟩m\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\langle {\\sigma (E_{\\mathrm{\\gamma max}})}\\rangle _{\ extrm{m}}$$\\end{document} for the 181Ta(γ,p)180mHf\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${^{181}\ extrm{Ta}}(\\gamma ,p)^{180\ extrm{m}}\ extrm{Hf}$$\\end{document} reaction were determined, and at Eγmax>55\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$E_{\\mathrm{\\gamma max}} > 55$$\\end{document} MeV obtained for the first time. The measured values, as well as the literature data, significantly (by more that an order of magnitude) exceed the theoretical flux-averaged cross-sections ⟨σ(Eγmax)⟩th\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\langle {\\sigma (E_{\\mathrm{\\gamma max}})}\\rangle _{\ extrm{th}}$$\\end{document}. 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A comparative analysis of the calculated total cross-sections from the TALYS computation for the reactions 181Ta(γ,p)180Hf\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${^{181}\ extrm{Ta}}(\\gamma ,p)^{180}\ extrm{Hf}$$\\end{document} and 181Ta(γ,n)180Ta\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${^{181}\ extrm{Ta}}(\\gamma ,n)^{180}\ extrm{Ta}$$\\end{document} was performed. It was shown that the photoproton (γ,p)\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$(\\gamma ,p)$$\\end{document} to photoneutron (γ,n)\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$(\\gamma ,n)$$\\end{document} strength ratio is consistent with the estimates based on the isospin selection rules and the value from the (e,e′p)\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$(e,e'p)$$\\end{document} experiment.

PbBPC4 involved in a xylem-deficient dwarf phenotype in pear by directly regulating the expression of PbXND1

Dwarfing is an important agronomic trait in fruit breeding. At present, dwarf cultivars or dwarfing rootstocks are used for high-density planting. Although some dwarf rootstocks have been used in the cultivation of pear (Pyrus bretschneideri Rehd), the breeding of dwarf pear rootstocks or cultivars is still sorely lacking. A previous study reported that PbXND1 results in a xylem-dwarf phenotype in pear trees. However, the regulatory mechanism upstream of PbXND1 is unclear. In this study, we identified PbBPC4 as an upstream regulatory factor of PbXND1 in yeast one-hybrid assays. In β-glucuronidase staining and dual-luciferase assays, PbBPC4 enhanced the activity of the PbXND1 promoter. Tobacco plants overexpressing PbBPC4 showed decreased plant height because of a reduced xylem size. Similar changes in the xylem was observed in transgenic pear roots; those overexpressing PbBPC4 showed reduced xylem size, and those with silencing PbBPC4 expression showed increased xylem size, greater density of xylem vessels, and a larger proportion of the xylem out of the total cross-section area. Expression analyses showed that PbBPC4 increases the transcription of PbXND1, leading to reduced transcript levels of genes involved in the positive regulation of xylem development, ultimately resulting in a xylem-deficient dwarf phenotype. Taken together, our results reveal the mechanism by which PbBPC4 participates in the regulation of xylem development via directly altering the expression of PbXND1, thus leading to the dwarf phenotype in pear. These findings have reference value for the breeding of dwarf pear trees.