Most theoretical approaches used in nuclear astrophysics to model the nucleosynthesis of heavy elements incorporate the so-called statistical model in order to describe the excitation and decay ...properties of atomic nuclei. One of the basic assumptions of this model is the validity of the Brink–Axel hypothesis and the related concept of so-called photon strength functions to describe γ-ray transition probabilities. We present a novel experimental approach that allows for the first time to experimentally determine the photon strength function simultaneously in two independent ways by a unique combination of quasi-monochromatic photon beams and a newly implemented γ–γ coincidence setup. This technique does not assume a priori the validity of the Brink–Axel hypothesis and sets a benchmark in terms of the detection sensitivity for measuring decay properties of photo-excited states below the neutron separation energy. The data for the spherical off-shell nucleus 128Te were obtained for γ-ray beam-energy settings between 3 MeV and 9 MeV in steps of 130 keV for the lower beam energies and in steps of up to 280 keV for the highest beam settings. We present a quantitative analysis on the consistency of the derived photon strength function with the Brink–Axel hypothesis. The data clearly demonstrate a discrepancy of up to a factor of two between the photon strength functions extracted from the photoabsorption and photon emission process, respectively. In addition, we observe that the photon strength functions are not independent of the excitation energy, as usually assumed. Thus, we conclude, that the Brink–Axel hypothesis is not strictly fulfilled in the excitation-energy region below the neutron separation threshold (Sn=8.78MeV) for the studied case of 128Te.
An austenitic stainless steel AISI 304 plate was functionally graded by interstitial alloying with nitrogen by high-temperature solution nitriding, resulting in a symmetrical nitrogen concentration ...profile over the plate thickness. The responses to plastic deformation and austenite stability were investigated by applying cold rolling up to 70 pct overall thickness reduction of the plate. Electron probe microanalysis, X-ray diffraction, electron microscopy, and hardness indentation were applied for characterization of the evolutions of nitrogen concentration profile, phase distribution, deformation microstructure, and hardness developing upon plastic deformation. The results demonstrate that the critical nitrogen content necessary to prevent deformation-induced martensite formation increases in the low-to-medium strain range, while it dramatically increases at high strain levels. With increasing nitrogen content, the dominant deformation mode evolves from deformation-induced martensite formation to a mixture of martensite and twin formation, and, eventually twinning and dislocation glide. The plastic strain regimes for the various deformation modes depend strongly on the nitrogen content. The results are discussed in relation to the effect of nitrogen content on the stacking fault energy of austenite in Fe–Cr–Ni alloys.
EURICA is a project at RIKEN Nishina Center aimed at studying a wide range of exotic nuclei through β-decay measurements and high-resolution γ-ray spectroscopy. The setup is located behind the ...BigRIPS fragment separator and the ZeroDegree spectrometer at the RIBF. EURICA consists of the HPGe cluster detectors from the previous Euroball and RISING projects, together with double-sided silicon-strip detectors for β-decay counting and lifetime measurements. In total, this setup provides us with the possibility to study several aspects of the exotic nuclei produced at the RIBF.
Histamine is a major mast cell mediator of immunoneural signalling in the gut and mast cells play a role in the pathophysiology
of functional and inflammatory bowel diseases. Histamine receptors are ...therefore promising drug targets to treat gut disorders.
We aimed to study the so far unknown effect of histamine on neural activity in the human enteric nervous system (ENS) and
to identify the pharmacology of histamine response. We used fast imaging techniques in combination with the potentiometric
dye di-8-ANEPPS to monitor directly membrane potential changes and thereby neuronal excitability in the human submucous plexus
from surgical specimens of 110 patients (2137 neurones, 273 ganglia). Local microejection of histamine resulted in action
potential discharge in 37% of neurones. This excitatory effect was mimicked by the H 1 agonist HTMT-dimaleat, H 2 agonist dimaprit, H 3 agonist ( R )-(â)-α-methylhistamine and H 4 agonist 4-methylhistamine. The excitatory actions of the agonists were specifically and selectively blocked by the H 1 , H 2 , H 3 or H 4 receptor antagonists pyrilamine, ranitidine, clobenpropit or J1-(5-chloro-1 H -indol-2-yl)carbonyl-4-methylpiperazine (JNJ 7777120), respectively. Clobenproprit reduced the excitatory response to histamine.
Unlike in the guinea-pig ENS ( R )-(â)-α-methylhistamine had no presynaptic actions in human submucous plexus. Application of agonists revealed receptor clustering
which was as follows: 29% H 1 /H 3 , 27% H 2 , 20% H 1 /H 2 /H 3 , 10% H 3 , 7% H 1 /H 2 and 7% H 2 /H 3 . Histamine excites human enteric neurones and this effect involves all four histamine receptors; most striking was the identification
of an excitatory H 3 mediated component and the discovery of H 4 mediated neuronal excitation. These data may form the basis of identification of new targets to treat inflammatory and functional
gut disorders.
Wilms tumor (WT) is the most common childhood renal cancer. Recent findings of mutations in microRNA (miRNA) processing proteins suggest a pivotal role of miRNAs in WT genesis. We performed miRNA ...expression profiling of 36 WTs of different subtypes and four normal kidney tissues using microarrays. Additionally, we determined the gene expression profile of 28 of these tumors to identify potentially correlated target genes and affected pathways. We identified 85 miRNAs and 2107 messenger RNAs (mRNA) differentially expressed in blastemal WT, and 266 miRNAs and 1267 mRNAs differentially expressed in regressive subtype. The hierarchical clustering of the samples, using either the miRNA or mRNA profile, showed the clear separation of WT from normal kidney samples, but the miRNA pattern yielded better separation of WT subtypes. A correlation analysis of the deregulated miRNA and mRNAs identified 13,026 miRNA/mRNA pairs with inversely correlated expression, of which 2844 are potential interactions of miRNA and their predicted mRNA targets. We found significant upregulation of miRNAs-183, -301a/b and -335 for the blastemal subtype, and miRNAs-181b, -223 and -630 for the regressive subtype. We found marked deregulation of miRNAs regulating epithelial to mesenchymal transition, especially in the blastemal subtype, and miRNAs influencing chemosensitivity, especially in regressive subtypes. Further research is needed to assess the influence of preoperative chemotherapy and tumor infiltrating lymphocytes on the miRNA and mRNA patterns in WT.
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On the brink of the phase transition from spherical to deformed Zr isotopes,
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Zr shows a co-existence of low-lying level structures with different degrees of quadrupole collectivity. Experimental ...data are available, but a coherent description of the measured properties is yet missing. This paper analyses available data and critically compiles the information relevant for the interpretation of the quadrupole-collective structure of
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Zr .
The dipole polarizability of stable even-mass tin isotopes 112,114,116,118,120,124Sn was extracted from inelastic proton scattering experiments at 295MeV under very forward angles performed at RCNP. ...Predictions from energy density functionals cannot account for the present data and the polarizability of 208Pb simultaneously. The evolution of the polarizabilities in neighboring isotopes indicates a kink at 120Sn while all model results show a nearly linear increase with mass number after inclusion of pairing corrections.
Direct proton-knockout reactions of Sc-55 at similar to 220 MeV/nucleon were studied at the RIKEN Radioactive Isotope Beam Factory. Populated states of Ca-54 were investigated through -ray and ...invariant-mass spectroscopy. Level energies were calculated from the nuclear shell model employing a phenomenological intemucleon interaction. Theoretical cross sections to states were calculated from distorted-wave impulse approximation estimates multiplied by the shell model spectroscopic factors, which describe the wave function overlap of the Sc-55 ground state with states in Ca-54. Despite the calculations showing a significant amplitude of excited neutron configurations in the ground-state of Sc-55, valence proton removals populated predominantly the ground state of Ca-54. This counterintuitive result is attributed to pairing effects leading to a dominance of the ground-state spectroscopic factor. Owing to the ubiquity of the pairing interaction, this argument should be generally applicable to direct knockout reactions from odd-even to even-even nuclei.
Neutron-rich nuclei in the vicinity of the N = 40 island of inversion are characterized by shell evolution and exhibit deformed ground states. In several nuclei isomeric states have been observed and ...attributed to excitations to the intruder neutron 1g(9/2) orbital. In the present paper we searched for isomeric states in nuclei around N = 40, Z = 22 produced by projectile fragmentation at the Radioactive Isotope Beam Factory. Delayed. rays were detected by the Euroball RIKEN Cluster Array germanium detector array gamma High statistics data allowed for an updated decay scheme of V-60. The lifetime of an isomeric state in V-64 was measured for the first time in the present experiment. A previously unobserved isomeric state was discovered in Sc-58. The measured lifetime suggests a parity changing transition, originating from an odd number of neutrons in the 1g(9/2) orbital. The nature of the isomeric state in Sc-58 is, thus, different from isomers in the less exotic V and Sc nuclei.
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