No abstract

The sorption properties of modified hydrolysis lignin towards Cu[Formula: see text], Zn[Formula: see text], Ni[Formula: see text], Co[Formula: see text] ions in the pH range from 2 to 8 at temperature of 298.15 K solution are studied. The analysis of kinetic curves of ions sorption on modified lignin at pH 7 shows that sorption equilibrium in heterogenic system ion–metal–sorbent is attained in 30–60 min. Obtained results indicate good equilibrium kinetic properties of sorbent. Supposed that reaction between sorbate and functional group of sorbent are the second-order reaction and they interact between each other in ratio 1:1. The character of the obtained electrokinetic curve suggests that the zeta potential of modified lignin strongly depends on the pH. The dependencies of cations metals sorption coefficients on the pH value of water phase are S-shaped. Maximal extraction of studied cations is observed at pH values of equilibrium solutions close to neutral ones.

No abstract

In the paper, investigation results of the uptake efficiency of radionuclides 60Co, 90Sr, and 137Cs dissolved in water onto iron oxides α-Fe2O3 and Fe3O4 are presented. It was found that sorption efficiency increased for higher pH values. Independent of the oxide nature, the uptake characteristics are the best toward 60Co and the worst toward 137Cs, forming the row as follows: 60Co > 90Sr > 137Cs. The highest sorption ability at pH 9 was found for magnetite Fe3O4, which was 93%, 73%, and 26% toward 60Co, 90Sr, and 137Cs, respectively, while the respective percentages for hematite α-Fe2O3 were 85%, 41%, and 18%. It was assumed that the main sorption mechanism was ion exchange. That may explain some decrease of the sorption efficiency in drinking water due to the interfering presence of magnesium and calcium cations. The obtained results indicated the feasibility of the tested sorbents and their merits, especially in terms of relatively high uptake coefficients, low costs, availability, and lack of toxicity.

No abstract

In the dynamics of the annual cycle (January, April, June, October) for 35 men and 35 women aged 18-22, born and permanently residing in the European North (64° N), there were determined the electrocardiograms’ amplitude-time characteristics. It has been established that in the annual cycle, the myocardium highest electrobiological activity was observed in the mid-seasons (autumn, spring). Seasonal changes of the cardiac muscle electric activity touched on the left heart greater than the right heart.

The results of comprehensive experimental research on two model frustrated systems of dilute ferrimagnetic oxides—the slightly anisotropic cubic spinels Li0.5Fe2.5−xGaxO4 and the highly anisotropic hexagonal BaFe12−xGaxO19—are reviewed and summarized. The concentration x-T phase diagrams constructed for this class of magnets for the first time are discussed, the mechanisms of formation of disordered states of the spin-glass type (with the role of the exchange interaction and anisotropy taken into account) are examined, and the structure of the states and the influence of spatial inhomogeneity of the cluster type are considered. It is shown for the example of the Li–Ga spinels that in this class of anisotropic Heisenberg magnets with short-range exchange the form of the x-T diagram differs from the canonical form for spin-glass systems: in the reentrant region (0.9⩽x⩽1.5) one observes a new cooperative frustrated state and a line of first-order phase transitions T1(x) terminating in a critical point at x=0.8.

Reentrant spinels Li0.5Fe2.5−xGaxO4 with x=0.9 and 1.2 display peaks on the temperature dependences of heat capacity C at T1=13.4 K (x=0.9) and 14.2 K (x=1.2) respectively, which are typical of a first-order phase transition. This transition is identified with the transformation of the collinear ferrimagnetic structure into a noncollinear structure preceding on the temperature scale the state of ferrimagnetic spin glass existing in the temperature range 0 K⩽T⩽Tf, where transition temperatures Tf are 9 K (x=0.9) and 12 K (x=1.2).