scholarly journals Intermediate-Energy Fragmentation of Heavy-Element Beams: A Novel Approach Towards the Nuclear Drip-Lines

2019 ◽  
Vol 10 ◽  
pp. 179
Author(s):  
G. A. Souliotis
Keyword(s):  
Lower Energy ◽  
Heavy Element ◽  
Experimental Studies ◽  
Intermediate Energy ◽  
Projectile Fragmentation ◽  
Heavy Nuclei ◽  
Novel Approach ◽  
Proton Radioactivity ◽  
R Process ◽  
Neutron Dripline

The fragmentation of heavy beams at intermediate energy and the opportunities offered by this in the exploration of heavy nuclei near the drip lines will be discussed. First, a study of 1 9 7Au projectile fragmentation at 30 MeV/nucleon will be presented in which an appreciable number of new p-rich nuclei were observed. Perspectives of proton radioactivity studies using the fragmentation approach will be discussed. Second, a study of the fission of 2 3 8U projectiles at 20 MeV/nucleon will be presented, where a number of new neutron rich nuclei were identified. Production rates of extremely η-rich nuclides from a typical projectile-fragmentation facility are given. A large number of nuclei along the astrophysical r-process path can be investigated and approach of the neutron dripline in the region Z=45-50 may be possible. The ability to produce and study these either p-rich or η-rich nuclei at intermediate (and possibly lower) energy facilities may open a variety of possibilities for experimental studies of exotic heavy nuclei.

Distribution of R- and S-Process Elements in the Galactic Halo

1988 ◽  
Vol 132 ◽  
pp. 501-506
Author(s):  
C. Sneden ◽  
C. A. Pilachowski ◽  
K. K. Gilroy ◽  
J. J. Cowan
Keyword(s):  
Heavy Element ◽  
Galactic Halo ◽  
Low Noise ◽  
Heavy Elements ◽  
Process Synthesis ◽  
Element Abundances ◽  
Halo Stars ◽  
Abundance Patterns ◽  
R Process ◽  
Process Elements

Current observational results for the abundances of the very heavy elements (Z>30) in Population II halo stars are reviewed. New high resolution, low noise spectra of many of these extremely metal-poor stars reveal general consistency in their overall abundance patterns. Below Galactic metallicities of [Fe/H] Ã −2, all of the very heavy elements were manufactured almost exclusively in r-process synthesis events. However, there is considerable star-to-star scatter in the overall level of very heavy element abundances, indicating the influence of local supernovas on element production in the very early, unmixed Galactic halo. The s-process appears to contribute substantially to stellar abundances only in stars more metal-rich than [Fe/H] Ã −2.

scholarly journals 10. General Discussion

1960 ◽  
Vol 10 ◽  
pp. 677-679 ◽  
Keyword(s):  
Yield Curve ◽  
Fission Products ◽  
Heavy Elements ◽  
Sikhote Alin ◽  
Heavy Nuclei ◽  
Fission Yield ◽  
Element Abundances ◽  
The Earth ◽  
R Process ◽  
Nova Outburst

1. p. SELINOV: Anomalous abundances of Te and Xe isotopes in meteorites and in the Earth permit us to draw some conclusions concerning the age of uranium and the processes of nucleogenesis. According to the estimate by Hoyle the amount of 254Cf disintegrated during a super-nova outburst is of the order of io29 g or io~4 of the stellar mass. According to the fission-yield curve the isotopes of Te comprise about 1 % of the mass of fission products. The abundances of Te 128-131 are anomalously high, due to the fission of heavy nuclei. The element abundances do not permit us to draw any conclusions about the r-process. The isotopes of Te and Xe with even mass numbers give evidence in favour of the r-process (anomalously high abundances). But the amount of Te in meteorites and in Earth is about 1000 times less than it should be if formed during the outburst. The Sikhote- Alin meteorite shows the same anomaly. We may conclude that the heavy elements of the solar system have been formed not in a single super-nova outburst, but as a result of mixing from the totality of outbursts. According to Hoyle, this gives a definite estimate for the age of uranium.

scholarly journals Pros and Cons of the Cannabinoid System in Cancer: Focus on Hematological Malignancies

Molecules ◽  
2021 ◽  
Vol 26 (13) ◽  
pp. 3866
Author(s):  
Natasha Irrera ◽  
Alessandra Bitto ◽  
Emanuela Sant’Antonio ◽  
Rita Lauro ◽  
Caterina Musolino ◽  
...  
Keyword(s):  
Cannabinoid Receptors ◽  
Hematological Malignancies ◽  
Antitumor Agents ◽  
Control Cell ◽  
Experimental Studies ◽  
Endocannabinoid System ◽  
Chemotherapeutic Agents ◽  
Cancer Cell Growth ◽  
Cell Functions ◽  
Novel Approach

The endocannabinoid system (ECS) is a composite cell-signaling system that allows endogenous cannabinoid ligands to control cell functions through the interaction with cannabinoid receptors. Modifications of the ECS might contribute to the pathogenesis of different diseases, including cancers. However, the use of these compounds as antitumor agents remains debatable. Pre-clinical experimental studies have shown that cannabinoids (CBs) might be effective for the treatment of hematological malignancies, such as leukemia and lymphoma. Specifically, CBs may activate programmed cell death mechanisms, thus blocking cancer cell growth, and may modulate both autophagy and angiogenesis. Therefore, CBs may have significant anti-tumor effects in hematologic diseases and may synergistically act with chemotherapeutic agents, possibly also reducing chemoresistance. Moreover, targeting ECS might be considered as a novel approach for the management of graft versus host disease, thus reducing some symptoms such as anorexia, cachexia, fatigue, anxiety, depression, and neuropathic pain. The aim of the present review is to collect the state of the art of CBs effects on hematological tumors, thus focusing on the essential topics that might be useful before moving into the clinical practice.

Sign dependence of spin polarization for secondary fragments produced following intermediate-energy projectile fragmentation

1997 ◽  
Vol 55 (5) ◽  
pp. 2501-2505 ◽  
Author(s):  
P. F. Mantica ◽  
R. W. Ibbotson ◽  
D. W. Anthony ◽  
M. Fauerbach ◽  
D. J. Morrissey ◽  
...  
Keyword(s):  
Spin Polarization ◽  
Intermediate Energy ◽  
Projectile Fragmentation

Hypoxic mechanisms in primary headaches

Cephalalgia ◽  
2016 ◽  
Vol 37 (4) ◽  
pp. 372-384 ◽  
Author(s):  
Josefine Britze ◽  
Nanna Arngrim ◽  
Henrik Winther Schytz ◽  
Messoud Ashina
Keyword(s):  
Cluster Headache ◽  
High Altitude ◽  
Acute Mountain Sickness ◽  
Experimental Studies ◽  
Epidemiological Studies ◽  
Primary Headaches ◽  
Secondary Headaches ◽  
Novel Approach ◽  
Calcitonin Gene ◽  
Level Of Knowledge

Background Hypoxia causes secondary headaches such as high-altitude headache (HAH) and headache due to acute mountain sickness. These secondary headaches mimic primary headaches such as migraine, which suggests a common link. We review and discuss the possible role of hypoxia in migraine and cluster headache. Methods This narrative review investigates the current level of knowledge on the relation of hypoxia in migraine and cluster headache based on epidemiological and experimental studies. Findings Epidemiological studies suggest that living in high-altitude areas increases the risk of migraine and especially migraine with aura. Human provocation models show that hypoxia provokes migraine with and without aura, whereas cluster headache has not been reliably induced by hypoxia. Possible pathophysiological mechanisms include hypoxia-induced release of nitric oxide and calcitonin gene-related peptide, cortical spreading depression and leakage of the blood-brain barrier. Conclusion There is a possible link between hypoxia and migraine and maybe cluster headache, but the exact mechanism is currently unknown. Provocation models of hypoxia have yielded interesting results suggesting a novel approach to study in depth the mechanism underlying hypoxia and primary headaches.

scholarly journals R-Process Nucleosynthesis in MHD Jet Explosions of Core-Collapse Supernovae

2013 ◽  
Vol 2013 ◽  
pp. 1-13
Author(s):  
Motoaki Saruwatari ◽  
Masa-aki Hashimoto ◽  
Ryohei Fukuda ◽  
Shin-ichiro Fujimoto
Keyword(s):  
Magnetic Field ◽  
Heavy Element ◽  
Initial Conditions ◽  
Core Collapse ◽  
Combined Effects ◽  
Two Dimensional ◽  
The Third ◽  
R Process ◽  
Helium Star ◽  
Hydrodynamic Code

We investigate the r-process nucleosynthesis during the magnetohydrodynamical (MHD) explosion of a supernova in a helium star of 3.3 M⊙, where effects of neutrinos are taken into account using the leakage scheme in the two-dimensional (2D) hydrodynamic code. Jet-like explosion due to the combined effects of differential rotation and magnetic field is able to erode the lower electron fraction matter from the inner layers. We find that the ejected material of low electron fraction responsible for the r-process comes out from just outside the neutrino sphere deep inside the Fe-core. It is found that heavy element nucleosynthesis depends on the initial conditions of rotational and magnetic fields. In particular, the third peak of the distribution is significantly overproduced relative to the solar system abundances, which would indicate a possible r-process site owing to MHD jets in supernovae.

scholarly journals The quest for AMS of 182Hf – why poor gas gives pure beams

2020 ◽  
Vol 232 ◽  
pp. 02003
Author(s):  
Martin Martschini ◽  
Johannes Lachner ◽  
Silke Merchel ◽  
Alfred Priller ◽  
Peter Steier ◽  
...  
Keyword(s):  
Detection Efficiency ◽  
Ion Source ◽  
Negative Ion ◽  
Complete Suppression ◽  
Buffer Gas ◽  
Novel Approach ◽  
First Results ◽  
Ion Laser ◽  
R Process ◽  
Ion Yields

The long-lived radioisotope 182Hf (T1/2 = 8.9 Ma) is of high astrophysical interest as its potential abundance in environmental archives would provide insight into recent r-process nucleosynthesis in the vicinity of our solar system. Despite substantial efforts, it could not be measured at natural abundances with conventional AMS so far due to strong isobaric interference from stable 182W. Equally important is an increase in ion source efficiency for the anions of interest. The new Ion Laser InterAction Mass Spectrometry (ILIAMS) technique at VERA tackles the problem of elemental selectivity in AMS with a novel approach. It achieves near-complete suppression of isobar contaminants via selective laser photodetachment of decelerated anion beams in a gas-filled radio-frequency quadrupole (RFQ) ion cooler. The technique exploits differences in electron affinities (EA) within elemental or molecular isobaric systems neutralizing anions with EAs smaller than the photon energy. Alternatively, these differences in EA can also facilitate anion separation via chemical reactions with the buffer gas. We present first results with this approach on AMS-detection of 182Hf. With He +O2 mixtures as buffer gas in the RFQ, suppression of 182WF5− vs 180HfF 5− by >105 has been demonstrated. Mass analysis of the ejected anion beam identified the formation of oxyfluorides as an important reaction channel. The overall Hf-detection efficiency at VERA presently is 1.4% and the W-corrected blank value is 182Hf/180Hf = (3.4 ± 2.1)×10−14. In addition, a survey of different sample materials for highest negative ion yields of HfF 5− with Cs-sputtering has been conducted.

scholarly journals Multi-Channel-Based Microgrid for Reliable Operation and Load Sharing

Energies ◽  
2019 ◽  
Vol 12 (11) ◽  
pp. 2070 ◽  
Author(s):  
Ali Elrayyah ◽  
Sertac Bayhan
Keyword(s):  
Control System ◽  
Critical Loads ◽  
Experimental Studies ◽  
Load Sharing ◽  
Reliable Operation ◽  
Performance Simulation ◽  
Power Exchange ◽  
Novel Approach ◽  
Active Channels ◽  
Level Of Importance

This paper presents a novel approach to distribute available power among critical and non-critical loads in microgrids. The approach is based on supplying power over a number of channels with distinguishable frequencies where loads could be served by these channels according to their level of importance. The multi-channel scheme not only offers flexibility to supply loads but also to share power among adjacent microgrids. The control system, which can deal with multi-channel scheme, is presented and different applications that can be offered whereby are discussed. The number of channels that can be supplied by any inverter is determined based on the parameters of the used filter. Moreover, the power exchange efficiencies over the active channels at various power levels are determined and approximated formulas for quick evaluation are presented. To verify the proposed solution performance, simulation and experimental studies were performed. The obtained results demonstrate the effectiveness of using multi-channel scheme for power exchange in microgrid and also confirm the accuracy of the provided formula related to power exchange efficiencies.

scholarly journals QCD AND QED DYNAMICS IN THE EMC EFFECT

2012 ◽  
Vol 21 (04) ◽  
pp. 1230002 ◽  
Author(s):  
LEONID FRANKFURT ◽  
MARK STRIKMAN
Keyword(s):  
Structure Function ◽  
Degrees Of Freedom ◽  
Experimental Studies ◽  
Momentum Conservation ◽  
Light Nuclei ◽  
Heavy Nuclei ◽  
Fermi Motion ◽  
Nucleon Wave Function ◽  
Emc Effect ◽  
Bjorken X

Applying exact QCD sum rules for the baryon charge and energy–momentum conservation we demonstrate that if the only degrees of freedom in nuclei were nucleons, the structure function of a nucleus would be the additive sum of the nucleon distributions at the same Bjorken x = AQ2/2(pA⋅q)≤0.5 up to very small Fermi motion corrections if 1/2mN x is significantly less than the nucleus radius. Hence QCD implies that the proper quantity to reveal violation of the additivity due to presence of nonnucleonic degrees of freedom in nuclei is the ratio RA(x, Q2) = (2/A)F2A(x, Q2)/F2D(x, Q2). Use of variable xp = Q2/2q0mp in the experimental studies instead of x leads to the deviation of RA(xp, Q2) from one even if the nucleus would consist only of nucleons with small momenta. Implementation of QCD dynamics accounts in the case of the light nuclei for at least a half of the deviation of RA(xp, Q2) from one for x≤0.55. In the case of heavy nuclei account of the QCD dynamics and of light-cone momentum fraction carried by Fermi, Weizsacker, Williams equivalent photons are responsible for ≈ one half the deviation of RA(x, Q2) from one at x≤0.55. We argue that direct observation of large and predominantly nucleonic short-range correlations (SRCs) in nuclei impacts strongly on the understanding of the EMC effect for x≥0.6 posing a serious challenge for most of the proposed models of the EMC effect. The data are consistent with a scenario in which the hadronic EMC effect reflects suppression of rare quark–gluon configurations in nucleons belonging to SRC appears to be the only viable. The dynamic realization of this scenario is presented in which quantum fluctuations of the nucleon wave function with x≥0.5 parton have a weaker interaction with nearby nucleons, leading to suppression of such configurations in bound nucleons and to the significant suppression of nucleon Fermi motion effects at x≥0.55 giving a right magnitude of the EMC effect. Implications of discussed effects for the analyses of the neutron structure function and nuclear parton distributions are presented. The directions for the future studies and challenging questions are outlined.

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