834 research outputs found

    A SHORT DESCRIPTION OF SCORZONERA PLANT SPECIES PRESENT IN ALEXANDRU BELDIE HERBARIUM FROM I.N.C.D.S. BUCHAREST

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    The present paper reunites the morphological and ecological description of Scorzonera plant species present in the Al. Beldie Herbarium from Marin Drăcea National Institute for Research and Development in Forestry (INCDS) in Bucharest. Furthermore, this article organizes the herbarium exemplars based on species, harvest year, the place from where they were taken and the specialist that has gathered them. The first part of the article starts with a short description of the herbarium and its specific, followed by presenting the material and method used in elaborating the paper. As such, the material is represented by the 83 plates containing exemplars of some Scorzonera species. A very important aspect which must be specified is the fact that the herbarium has a significant number of rare endangered or endemic specimens. One example, the protect species Scorzonerarosea, is present in the herbarium with 26 plates that were mainly gathered in the year 1936 by Al. Beldie himself.  Another rare species, Scorzonera hispanica, is represented in 16 plates from within the herbarium and is of a high interest as it is the oldest species of the genre, being harvested in the year 1794. Beside the description of the gathered Scorzonera species, the present paper presents the gathering map of the species present in the herbarium at an European level, together with analyzing the gathering periods of these species. Some of the oldest gathered species are also presented in this article. The paper ends with some conclusions regarding the Scorzonera species’ analysis and exemplars present in the herbarium, while briefly presenting their most novel aspects and characteristics.

    Observing Nearby Nuclei on Paramagnetic Trityls and MOFs via DNP and Electron Decoupling

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    Dynamic nuclear polarization (DNP) is an NMR sensitivity enhancement technique that mediates polarization transfer from unpaired electrons to NMR-active nuclei. Despite its success in elucidating important structural information on biological and inorganic materials, the detailed polarization-transfer pathway from the electrons to the nearby and then the bulk solvent nuclei, and finally to the molecules of interest-remains unclear. In particular, the nuclei in the paramagnetic polarizing agent play significant roles in relaying the enhanced NMR polarizations to more remote nuclei. Despite their importance, the direct NMR observation of these nuclei is challenging because of poor sensitivity. Here, we show that a combined DNP and electron decoupling approach can facilitate direct NMR detection of these nuclei. We achieved an ∼80 % improvement in NMR intensity via electron decoupling at 0.35 T and 80 K on trityl radicals. Moreover, we recorded a DNP enhancement factor of urn:x-wiley:09476539:media:chem202202556:chem202202556-math-0001 ∼90 and ∼11 % higher NMR intensity using electron decoupling on paramagnetic metal-organic framework, magnesium hexaoxytriphenylene (MgHOTP MOF)

    Large scale shell model calculations for odd-odd 58−62^{58-62}Mn isotopes

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    Large scale shell model calculations have been carried out for odd-odd 58−62^{58-62}Mn isotopes in two different model spaces. First set of calculations have been carried out in full fp\it{fp} shell valence space with two recently derived fp\it{fp} shell interactions namely GXPF1A and KB3G treating 40^{40}Ca as core. The second set of calculations have been performed in fpg9/2{fpg_{9/2}} valence space with the fpgfpg interaction treating 48^{48}Ca as core and imposing a truncation by allowing up to a total of six particle excitations from the 0f7/2_{7/2} orbital to the upper fp\it{fp} orbitals for protons and from the upper fp\it{fp} orbitals to the 0g9/2_{9/2} orbital for neutron. For low-lying states in 58^{58}Mn, the KB3G and GXPF1A both predicts good results and for 60^{60}Mn, KB3G is much better than GXPF1A. For negative parity and high-spin positive parity states in both isotopes fpgfpg interaction is required. Experimental data on 62^{62}Mn is sparse and therefore it is not possible to make any definite conclusions. More experimental data on negative parity states is needed to ascertain the importance of 0g9/2_{9/2} and higher orbitals in neutron rich Mn isotopes.Comment: 5 pages, 4 figures, Submitted to Eur. Phys. J.

    Spectroscopy of the odd-odd fp-shell nucleus 52Sc from secondary fragmentation

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    The odd-odd fp-shell nucleus 52Sc was investigated using in-beam gamma-ray spectroscopy following secondary fragmentation of a 55V and 57Cr cocktail beam. Aside from the known gamma-ray transition at 674(5)keV, a new decay at E_gamma=212(3) keV was observed. It is attributed to the depopulation of a low-lying excited level. This new state is discussed in the framework of shell-model calculations with the GXPF1, GXPF1A, and KB3G effective interactions. These calculations are found to be fairly robust for the low-lying level scheme of 52Sc irrespective of the choice of the effective interaction. In addition, the frequency of spin values predicted by the shell model is successfully modeled by a spin distribution formulated in a statistical approach with an empirical, energy-independent spin-cutoff parameter.Comment: accepted for publication in PR

    Evolution of the E(1/21+)−E(3/21+)E(1/2^+_1)-E(3/2^+_1) energy spacing in odd-mass K, Cl and P isotopes for N=20−28N=20-28

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    The energy of the first excited state in the neutron-rich N=28 nucleus 45Cl has been established via in-beam gamma-ray spectroscopy following proton removal. This energy value completes the systematics of the E(1/2^+_1)-E(3/2^+_1) level spacing in odd-mass K, Cl and P isotopes for N=20-28. The results are discussed in the framework of shell-model calculations in the sd-fp model space. The contribution of the central, spin-orbit and tensor components is discussed from a calculation based on a proton single-hole spectrum from G-matrix and pi + rho meson exchange potentials. A composite model for the proton 0d_{3/2}-1s_{1/2} single-particle energy shift is presented.Comment: Phys. Rev. C, in pres

    One-neutron knockout in the vicinity of the N=32 sub-shell closure: 9Be(57Cr,56Cr+ gamma)X

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    The one-neutron knockout reaction 9Be(57Cr,56Cr + gamma)X has been measured in inverse kinematics with an intermediate-energy beam. Cross sections to individual states in 56Cr were partially untangled through the detection of the characteristic gamma-ray transitions in coincidence with the reaction residues. The experimental inclusive longitudinal momentum distribution and the yields to individual states are compared to calculations that combine spectroscopic factors from the full fp shell model and nucleon-removal cross sections computed in a few-body eikonal approach.Comment: PRC, in pres

    Z=50 shell gap near 100^{100}Sn from intermediate-energy Coulomb excitations in even-mass 106−−112^{106--112}Sn isotopes

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    Rare isotope beams of neutron-deficient 106,108,110^{106,108,110}Sn nuclei from the fragmentation of 124^{124}Xe were employed in an intermediate-energy Coulomb excitation experiment yielding B(E2,01+→21+)B(E2, 0^+_1 \to 2^+_1) transition strengths. The results indicate that these B(E2,01+→21+)B(E2,0^+_1 \to 2^+_1) values are much larger than predicted by current state-of-the-art shell model calculations. This discrepancy can be explained if protons from within the Z = 50 shell are contributing to the structure of low-energy excited states in this region. Such contributions imply a breaking of the doubly-magic 100^{100}Sn core in the light Sn isotopes.Comment: 4 pages, 4 figure

    Variation with mass of \boldmath{B(E3; 0_1^+ \to 3_1^-)} transition rates in A=124−134A=124-134 even-mass xenon nuclei

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    B(E3;01+→31−)B(E3; 0_1^+ \to 3_1^-) transition matrix elements have been measured for even-mass 124−134^{124-134}Xe nuclei using sub-barrier Coulomb excitation in inverse kinematics. The trends in energy E(3−)E(3^-) and B(E3;01+→31−)B(E3; 0_1^+ \to 3_1^-) excitation strengths are well reproduced using phenomenological models based on a strong coupling picture with a soft quadrupole mode and an increasing occupation of the intruder h11/2h_{11/2} orbital.Comment: 5 pages, 4 figures, PRC in pres
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