Cations such as Mg2+ regulate spillover of absorbed excitation energy mainly in favour of photosystem (PS) 2. Effect of low concentration (<10 mM) of the monovalent cation Na+ on chlorophyll (Chl) a fluorescence was completely overridden by divalent cation Mg2+ (5 mM). Based on Chl a fluorescence yield and 77 K emission measurements, we revealed the role and effectiveness of anions (Cl-, SO42-, PO43-) in lowering the Mg2+-induced PS2 fluorescence. The higher the valency of the anion, the lesser was the expression of Mg2+ effect. Anions may thus overcome Mg2+ effects up to certain extent in a valency dependent manner, thereby diverting more energy to PS1 even in the presence of MgCl2. They may do so by reversing Mg2+-induced changes. and Anjana Jajoo, Sudhakar Bharti.
Let G be an undirected connected graph with n, n\geqslant 3, vertices and m edges with Laplacian eigenvalues µ^{1}\geqslant µ_{2}\geq ...\geq µ_{n-1> µ_{n}}=0. Denote by {\mu _I} = {\mu _{{r_1}}} + {\mu _{{r_2}}} + \ldots + {\mu _{{r_k}}}, 1\leq k\leq n-2, 1\leq r_{1}< r_{2}< ...< r_{k} \leq n-1, the sum of k arbitrary Laplacian eigenvalues, with {\mu _{{I_1}}} = {\mu _1} + {\mu _2} + \ldots + {\mu _k} and {\mu _{{I_n}}} = {\mu _{n - k}} + \ldots + {\mu _{n - 1}}. Lower bounds of graph invariants {\mu _{{I_1}}} - {\mu _{{I_n}}} and {\mu _{{I_1}}}/{\mu _{{I_n}}} are obtained. Some known inequalities follow as a special case., Igor Ž. Milovanović, Emina I. Milovanović, Edin Glogić., and Obsahuje seznam literatury