743 research outputs found
SHORT CHARACTERIZATION OF PLANT SPECIES FROM CENTAUREA GENUS PRESENT IN ”AL. BELDIE” HERBARIUM FROM ”MARIN DRĂCEA” NATIONAL INSTITUTE FOR RESEARCH AND DEVELOPMENT IN FORESTRY - BUCHAREST
”Al Beldie” herbarium from ”Marin Drăcea” National Institute for Research and Development in Forestry is an important herbarium with a significant role in the present research paper.This herbarium is ilisted in Index Herbaria and is composed of approximately 60.000 sheets with dried specimens of plants. From those 60.000 sheets, 71 belong to the genus Centaurea, with 19 species to be more precise. All of these species were collected by known personalities in the field of systematic botany, most of them being Romanian. The species were collected between 1855 and 1951 from the entire world, with a great majority from Romania. The aim of this article is to describe some species of Centaurea that are present in this herbarium. In this way it can be observed how important it is to collect, identify and preserve sheets with dried species in herbarium, given that these species of plants can be very hard to identify
A SHORT DESCRIPTION OF SCORZONERA PLANT SPECIES PRESENT IN ALEXANDRU BELDIE HERBARIUM FROM I.N.C.D.S. BUCHAREST
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
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)
Electron drift-mobility measurements in polycrystalline CuIn1-xGaxSe2 solar cells
We report photocarrier time-of-flight measurements of electron drift mobilities for the p-type CuIn1-xGaxSe2 films incorporated in solar cells. The electron mobilities range from 0.02 to 0.05 cm^2/Vs and are weakly temperature-dependent from 100–300 K. These values are lower than the range of electron Hall mobilities (2-1100 cm2/Vs) reported for n-type polycrystalline thin films and single crystals. We propose that the electron drift mobilities are properties of disorder-induced mobility edges and discuss how this disorder could increase cell efficiencies
Evolution of the energy spacing in odd-mass K, Cl and P isotopes for
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
Large scale shell model calculations for odd-odd Mn isotopes
Large scale shell model calculations have been carried out for odd-odd
Mn isotopes in two different model spaces. First set of calculations
have been carried out in full shell valence space with two recently
derived shell interactions namely GXPF1A and KB3G treating Ca
as core. The second set of calculations have been performed in
valence space with the interaction treating Ca as core and
imposing a truncation by allowing up to a total of six particle excitations
from the 0f orbital to the upper orbitals for protons and
from the upper orbitals to the 0g orbital for neutron. For
low-lying states in Mn, the KB3G and GXPF1A both predicts good results
and for Mn, KB3G is much better than GXPF1A. For negative parity and
high-spin positive parity states in both isotopes interaction is
required. Experimental data on 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 0g and higher
orbitals in neutron rich Mn isotopes.Comment: 5 pages, 4 figures, Submitted to Eur. Phys. J.
Two-neutron knockout from neutron-deficient Ar, S, and Si
Two-neutron knockout reactions from nuclei in the proximity of the proton
dripline have been studied using intermediate-energy beams of neutron-deficient
Ar, S, and Si. The inclusive cross sections, and also the
partial cross sections for the population of individual bound final states of
the Ar, S and Si knockout residues, have been determined
using the combination of particle and -ray spectroscopy. Similar to the
two-proton knockout mechanism on the neutron-rich side of the nuclear chart,
these two-neutron removal reactions from already neutron-deficient nuclei are
also shown to be consistent with a direct reaction mechanism.Comment: Phys. Rev. C, rapid communication, in pres
The isolated Erebia pandrose Apennine population is genetically unique and endangered by climate change
Climate change is causing shifts in the distribution of many species and populations inhabiting mountain tops are particularly vulnerable to these threats because they are constrained in altitudinal shifts. Apennines are a relatively narrow and low mountain chain located in Southern Europe, which hosts many isolated populations of mountain species. The butterfly Erebia pandrose was recorded for the last time in the Apennines in 1977, on the top of a single massif (Monti della Laga).
We confirmed the presence of a small, isolated population of E. pandrose in the Apennines, at a distance of more than 400 km to any other known populations. Then, we examined the cytochrome c oxidase subunit 1 mitochondrial DNA marker of this species across the Palaearctic area and estimated the potential decline over the Alps and the Apennines due to future climatic changes.
The Apennine population represents an endemic lineage characterised by eight mutations over the 658 bp analysed (1.2%). In the Alps and Apennines, this species has shifted uphill more than 3 m per year since the end of the 19th century and more than 22 m per year since 1995. Species distribution models suggested that these mountain populations will experience a generalised loss of climatic suitability, which, according to our projections, could lead to the extinction of the Apennine population in a few decades.
Erebia pandrose has the potential to become a flagship species for advertising the risk of losing unique fractions of genetic diversity for mountain species
Shell structure at N=28 near the dripline: spectroscopy of Si, P and S
Measurements of the N=28 isotones 42Si, 43P and 44S using one- and two-proton
knockout reactions from the radioactive beam nuclei 44S and 46Ar are reported.
The knockout reaction cross sections for populating 42Si and 43P and a 184 keV
gamma-ray observed in 43P establish that the d_{3/2} and s_{1/2} proton orbits
are nearly degenerate in these nuclei and that there is a substantial Z=14
subshell closure separating these two orbits from the d_{5/2} orbit. The
increase in the inclusive two-proton knockout cross section from 42Si to 44S
demonstrates the importance of the availability of valence protons for
determining the cross section. New calculations of the two-proton knockout
reactions that include diffractive effects are presented. In addition, it is
proposed that a search for the d_{5/2} proton strength in 43P via a higher
statistics one-proton knockout experiment could help determine the size of the
Z=14 closure.Comment: Phys. Rev. C, in pres
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