Studying interactions of radioactive ions with neutrons is particularly demanding and has been performed only in a few cases. Some of these interactions are crucial in several astrophysical contexts. ...In the present work, the case of the 7Be destruction induced by the (n, ) reaction is investigated at the energies typical of the primordial nucleosynthesis by means of the Trojan Horse Method applied to the 2H(7Be, )p quasi-free reaction. The 7Be(n, )4He cross-section has been measured in a single experiment from ∼2 MeV down to cosmological energies. The corresponding deduced reaction rate has been adopted to evaluate the impact on big bang nucleosynthesis and on the lithium problem.
The potent analgesic effects of cannabis-like drugs and the presence of CB1-type cannabinoid receptors in pain-processing areas of the brain and spinal cord indicate that endogenous cannabinoids such ...as anandamide may contribute to the control of pain transmission within the central nervous system (CNS). Here we show that anandamide attenuates the pain behaviour produced by chemical damage to cutaneous tissue by interacting with CB1-like cannabinoid receptors located outside the Palmitylethanolamide (PEA), which is released together with anandamide from a common phospholipid precursor, exerts a similar effect by activating peripheral CB2-like receptors. When administered together, the two compounds act synergistically, reducing pain responses 100-fold more potently than does each compound alone. Gas-chromatography/mass-spectrometry measurements indicate that the levels of anandamide and PEA in the skin are enough to cause a tonic activation of local cannabinoid receptors. In agreement with this possibility, the CB1 antagonist SR141716A and the CB2 antagonist SR144528 prolong and enhance the pain behaviour produced by tissue damage. These results indicate that peripheral CB1-like and CB2-like receptors participate in the intrinsic control of pain initiation and that locally generated anandamide and PEA may mediate this effect.
The endocannabinoid system may serve important functions in the central and peripheral regulation of pain. In the present study, we investigated the effects of the endocannabinoid transport inhibitor ...AM404 N-(4-hydroxyphenyl)-eicosa-5,8,11,14-tetraenamide on rodent models of acute and persistent nociception (intraplantar formalin injection in the mouse), neuropathic pain (sciatic nerve ligation in the rat), and inflammatory pain (complete Freund's adjuvant injection in the rat). In the formalin model, administration of AM404 (1-10 mg/kg i.p.) elicited dose-dependent antinociceptive effects, which were prevented by the CB(1) cannabinoid receptor antagonist rimonabant (SR141716A; 1 mg/kg i.p.) but not by the CB2 antagonist SR144528 (1 mg/kg i.p.) or the vanilloid antagonist capsazepine (30 mg/kg i.p.). Comparable effects were observed with UCM707 N-(3-furylmethyl)-eicosa-5,8,11,14-tetraenamide, another anandamide transport inhibitor. In both the chronic constriction injury and complete Freund's adjuvant model, daily treatment with AM404 (1-10 mg/kg s.c.) for 14 days produced a dose-dependent reduction in nocifensive responses to thermal and mechanical stimuli, which was prevented by a single administration of rimonabant (1 mg/kg i.p.) and was accompanied by decreased expression of cyclooxygenase-2 and inducible nitric-oxide synthase in the sciatic nerve. The results provide new evidence for a role of the endocannabinoid system in pain modulation and point to anandamide transport as a potential target for analgesic drug development.
Shell structure and magic numbers in atomic nuclei were generally explained by pioneering work that introduced a strong spin-orbit interaction to the nuclear shell model potential. However, knowledge ...of nuclear forces and the mechanisms governing the structure of nuclei, in particular far from stability, is still incomplete. In nuclei with equal neutron and proton numbers (N = Z), enhanced correlations arise between neutrons and protons (two distinct types of fermions) that occupy orbitals with the same quantum numbers. Such correlations have been predicted to favour an unusual type of nuclear superfluidity, termed isoscalar neutron-proton pairing, in addition to normal isovector pairing. Despite many experimental efforts, these predictions have not been confirmed. Here we report the experimental observation of excited states in the N = Z = 46 nucleus (92)Pd. Gamma rays emitted following the (58)Ni((36)Ar,2n)(92)Pd fusion-evaporation reaction were identified using a combination of state-of-the-art high-resolution γ-ray, charged-particle and neutron detector systems. Our results reveal evidence for a spin-aligned, isoscalar neutron-proton coupling scheme, different from the previous prediction. We suggest that this coupling scheme replaces normal superfluidity (characterized by seniority coupling) in the ground and low-lying excited states of the heaviest N = Z nuclei. Such strong, isoscalar neutron-proton correlations would have a considerable impact on the nuclear level structure and possibly influence the dynamics of rapid proton capture in stellar nucleosynthesis.
The elastic scattering in the reaction
7
Li+
208
Pb was investigated in the bombarding energy range from 25 to 39 MeV. The real and imaginary parts of the optical potential were analyzed by using a ...phenomenological potential. A dispersion relation analysis is presented in order to investigate the threshold anomaly effect. It is concluded that
7
Li has an intermediate behavior between the tightly bound nuclei such as
16
O and the loosely bound nuclei such as
6
Li where the lack of the threshold anomaly is unambiguously observed. Reaction cross sections are also extracted from the elastic scattering data and its comparison with the ones of other systems has been performed to draw hints on the effect of the breakup channel.
The endogenous fatty acid ethanolamide, palmitylethanolamide, alleviated, in a dose-dependent manner, pain behaviors elicited in mice by injections of formalin (5%, intraplantar), acetic acid (0.6%, ...0.5 ml per animal, intraperitoneal, i.p.), kaolin (2.5 mg per animal, i.p.), and magnesium sulfate (120 mg per kg, i.p.). The antinociceptive effects of palmitylethanolamide were prevented by the cannabinoid CB
2 receptor antagonist SR144528
N-(1
s-endo-1.3.3-trimethylbicyclo2.3.1heptan-2-yl)-5-(4-chloro-3-methylphenyl)-1-(4-methylbenzyl)-pyrazole-3-carboxamide, not by the cannabinoid CB
1 receptor antagonist SR141716A
N-(piperidin-1-yl)-5-(4-chlorophenyl)-1-(2,4-dichlorophenyl)-4-methyl-1
H-pyrazole-3-carboxamide·HCl. By contrast, palmitylethanolamide had no effect on capsaicin-evoked pain behavior or thermal nociception. The endogenous cannabinoid, anandamide (arachidonylethanolamide), alleviated nociception in all tests (formalin, acetic acid, kaolin, magnesium sulfate, capsaicin and hot plate). These effects were prevented by the cannabinoid CB
1 receptor antagonist SR141716A, not the cannabinoid CB
2 receptor antagonist SR141716A. Additional fatty acid ethanolamides (oleylethanolamide, myristylethanolamide, palmitoleylethanolamide, palmitelaidylethanolamide) had little or no effect on formalin-evoked pain behavior, and were not investigated in other pain models. These results support the hypothesis that endogenous palmitylethanolamide participates in the intrinsic control of pain initiation. They also suggest that the putative receptor site activated by palmitylethanolamide may provide a novel target for peripherally acting analgesic drugs.
Smoking marijuana or administration of its main active constituent, Δ
9-tetrahydrocannabinol (Δ9-THC), may exert potent
dilating effects on human airways. But the physiological
significance of this ...observation and its potential therapeutic value are obscured
by the fact that some asthmatic patients respond to these compounds with
a paradoxical bronchospasm. The mechanisms underlying these
contrasting responses remain unresolved. Here we show that the endogenous
cannabinoid anandamide exerts dual effects on bronchial responsiveness in
rodents: it strongly inhibits bronchospasm and cough evoked by the chemical
irritant, capsaicin, but causes bronchospasm when the constricting tone exerted
by the vagus nerve is removed. Both effects are mediated through peripheral
CB1 cannabinoid receptors found on axon terminals of airway nerves. Biochemical
analyses indicate that anandamide is synthesized in lung tissue on calcium-ion
stimulation, suggesting that locally generated anandamide participates in
the intrinsic control of airway responsiveness. In support of this conclusion,
the CB1 antagonist SR141716A enhances capsaicin-evoked bronchospasm and cough.
Our results may account for the contrasting bronchial actions of cannabis-like
drugs in humans, and provide a framework for the development of more selective
cannabinoid-based agents for the treatment of respiratory pathologies.
Shell structure and magic numbers in atomic nuclei were generally explained by pioneering work$^{1}$ that introduced a strong spin-orbit interaction to the nuclear shell model potential. However, ...knowledge of nuclear forces and the mechanisms governing the structure of nuclei, in particular far from stability, is still incomplete. In nuclei with equal neutron and proton numbers (N=Z), enhanced correlations arise between neutrons and protons (two distinct types of fermions) that occupy orbitals with the same quantum numbers. Such correlations have been predicted to favour an unusual type of nuclear superfluidity, termed isoscalar neutron- proton pairing $^{2,3,4,5,6}$, in addition to normal isovector pairing. Despite many experimental efforts, these predictions have not been confirmed. Here we report the experimental observation of excited states in the N =Z 46 nucleus $^{92}$Pd. Gamma rays emitted following the $^{58}Ni(^{36}Ar,2n) ^{92}$Pd fusion-evaporation reaction were identified using a combination of state-of-the-art high-resolution c-ray, charged-particle and neutron detector systems. Our results reveal evidence for a spin-aligned, isoscalar neutron-proton coupling scheme, different from the previous prediction $^{2,3,4,5,6}$. We suggest that this coupling scheme replaces normal superfluidity (characterized by seniority coupling$^{7,8}$ in the ground and low-lying excited states of the heaviest N =Z nuclei. Such strong, isoscalar neutron-proton correlations would have a considerable impact on the nuclear level structure and possibly influence the dynamics of rapid proton capture in stellar nucleosynthesis.
The elastic scattering process for the nuclear reactions induced by the Radioactive Ion Beams 7Be and 8B on a 208Pb target was measured for the first time in the energy range around the Coulomb ...barrier. Extensive theoretical calculations within the framework of the optical model were performed. An excellent agreement between experimental data and theoretical predictions was achieved for the reaction 7Be + 208Pb, while a comprehensive understanding of the reaction dynamics induced by the more exotic projectile 8B is still far to be reached. Predictions of the cross section for the breakup for both systems will also be given.
Nuclear viscosity is an indispensable ingredient of the nuclear fission collective dynamical models. It governs the exchange of energy between the collective variables and the thermal bath. Its ...dependence on the shape and temperature is a matter of controversy. By using systems of intermediate fissility we have demonstrated in a recent study that the viscosity parameters is larger for compact shapes, and decreases for larger deformations of the fissioning system, at variance with the conclusions of the statistical model modified to include empirically viscosity and time scales. In this contribution we propose an experimental scenario to highlight the possible dependence of the viscosity from the temperature.
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