Search results for " Potassium"
showing 10 items of 101 documents
Spectroscopy of very neutron-deficient 187,189Bi isotopes
2003
Shape coexistence is well known to occur in nuclei, in particular near closed shells [1], where particle-hole excitations across the shell gap can create deformed intruder states. In the neutron-deficient lead isotopes (Z = 82), deformed structures appear at low excitation energy. The isotope 188Pb [2] shows for example a triple shape coexistence with oblate and prolate excited 0+ states that compete with the spherical ground state. The study of the odd-proton single-particle excitations in Bi isotopes allows to obtain information on the orbitals involved in the different shapes observed in this mass region.
Shell structure of potassium isotopes deduced from their magnetic moments
2014
\item[Background] Ground-state spins and magnetic moments are sensitive to the nuclear wave function, thus they are powerful probes to study the nuclear structure of isotopes far from stability. \item[Purpose] Extend our knowledge about the evolution of the $1/2^+$ and $3/2^+$ states for K isotopes beyond the $N = 28$ shell gap. \item[Method] High-resolution collinear laser spectroscopy on bunched atomic beams. \item[Results] From measured hyperfine structure spectra of K isotopes, nuclear spins and magnetic moments of the ground states were obtained for isotopes from $N = 19$ up to $N = 32$. In order to draw conclusions about the composition of the wave functions and the occupation of the …
Potassium deficiency and drought stress in grapevine cultivars
2014
Potassium availability affects drought responses in plants through several metabolic roles, among which stomatal regulation, cell growth and xylem hydraulics. Vitis vinifera L. is a highly valuable crop and several genotypes have been selected during its millennial cultivation. Varieties show differences in their adaptability to stress conditions, making them more or less suitable to certain climatic and edaphic conditions. The varieties cultivated in Sicily are characterized by high variability. We investigated the response of two Sicilian cultivars (Nero d'Avola and Catarratto) to potassium deficiency and drought stress. Two-year-old grafted plants were grown in agriperlite, with or witho…
Recovery from water stress in laurel plants: influence of short term potassium fertilization
2013
Plant xylem hydraulic conductance varies with changes in sap solute concentrations, particularly potassium, a phenomenon known as 'ionic effect'. In well-watered Laurus nobilis plants, short term potassium fertilization increased xylem sap potassium concentration, resulting in an increase in plant hydraulic conductance (Kplant), leaf-specific conductivity of the shoot (kshoot) and transpiration rate (Eplant). The ionic effect is enhanced in embolized stems, where it can compensate the cavitation-induced loss of hydraulic conductance. The aim of this work was to test if water-stressed potassium-starved laurel plants could recover earlier from stress when irrigated with a potassium solution i…
CCDC 947464: Experimental Crystal Structure Determination
2013
Related Article: Anssi Peuronen, Esa Lehtimäki, and Manu Lahtinen|2013|Cryst.Growth Des.|13|4615|doi:10.1021/cg401246n
CCDC 1996427: Experimental Crystal Structure Determination
2020
Related Article: Júlia Mayans, Constantinos C. Stoumpos, Mercé Font-Bardia, Albert Escuer|2020|Chem.-Eur.J.|26|11158|doi:10.1002/chem.202001900
CCDC 1996425: Experimental Crystal Structure Determination
2020
Related Article: Júlia Mayans, Constantinos C. Stoumpos, Mercé Font-Bardia, Albert Escuer|2020|Chem.-Eur.J.|26|11158|doi:10.1002/chem.202001900
Apigenin‐induced nitric oxide production involves calcium‐activated potassium channels and is responsible for antiangiogenic effects
2007
Summary. Background: The dietary flavonoid apigenin (Api) has been demonstrated to exert multiple beneficial effects upon the vascular endothelium. The aim of this study was to examine whether Ca2+-activated K+ channels (KCa) are involved in endothelial nitric oxide (NO) production and antiangiogenic effects.Methods: Endothelial NO generation was monitored using a cyclic guanosine monophosphate radioimmunoassay. KCa activity and changes of the intracellular Ca2+ concentration [Ca2+]i were analyzed using the fluorescent dyes bis-barbituric acid oxonol, potassium-binding benzofuran isophthalate, and fluo-3. The endothelial angiogenic parameters measured were cell proliferation, [3H]-thymidine…
Ion transport through membranes: A computer experiment
1983
Abstract Gramicidin-A is a linear pentadecapeptide antibiotic, which forms transmembrane channels; these have a number of interesting conductance characteristics [1, 2 and Refs. therein], as for example high specific ion fluxes (a single channel carries about 10 7 sodium ions/sec at 25 °C, 1 M NaCl and 100 mV transmembrane d.d.p.) have a remarkable ion selectivity among the monovalent cations. The permeability ratios with respect to sodium were found to be in following order H + (150) > NH 4 + (8.9) > Cs + (5.8) > Rb + (5.5) > K + (3.9) > Na + (1.0) > Li + (0.33). The channel is impermeable to anions and to divalent cations and it exhibits saturation and maxima in conductance as a function …
Effect of potassium fertilization on the hydraulic conductance of laurel plants
2009
The effect of potassium fertilization on hydraulic conductance was tested in 2-year-old potted laurel seedlings, grown in a greenhouse at the Botanical Garden of Palermo. Plants were divided into a control group (+K) and a potassium starved group (-K). A set of randomly chosen -K plants received irrigation with 25 mM KCl (KCl plants) 24 hours before measurements, to test the short term effect of potassium fertilization. Measurements were carried out in July and October 2008. Whole-plant hydraulic conductance was measured by the evaporative flux method; root and shoot hydraulic conductance were measured by the vacuum chamber. Potassium availability or season did not significantly affect leaf…