SOUTHERN JOURNAL OF SCIENCES

During the construction of concrete structures of small cross-sections, the release of heat during cementhardening has no harmful effects. With the increasing temperature of the hardening cement mass, the rate ofcement hydration increases. This increases the rate of release of its heat of hydration of cement. Theconsequence of the accelerated process of hydration of the binder is a more intensive increase in the strengthof cement stone than in the case of hardening under normal conditions. This fact is widely used in practice forthe intensification of the hardening of concrete. When structures with small cross-sections are being built, theheat released during hardening is relatively quickly transferred to the surrounding space and does not cause asignificant increase in temperature. In structures made of massive concrete (with a large cross-section), thisheat is stored in the interior of the array for a long time, which causes a rather large rise in temperature and itsslow drop. This is due to the fact that heat transfer to the external environment is hampered here by theconsiderable thickness of the massif and the rapid rate of concreting, mechanized laying of large masses ofconcrete. As a result, a temperature difference is created between the internal and external parts of thestructure and harmful internal stresses arise that can cause cracking in the hardened concrete. This leads to aviolation of its solidity. The faster cement hydrates, the sooner and more heat is released. The types of cementswith a high content of tricalcium silicate and aluminate emit more heat and rather than types of cement with ahigh content of dicalcium silicate and tetra-calcium aluminoferrite. However, the latter has a lower strength. Theincrease in strength resulting from the hydration process is inevitably associated with the release of heat into theenvironment. C

Sugar beet is a crop able to resist high levels of soil salinity after emergence and establishment. Considering the significant difference in the effect of nitrogen forms on sugar beet performance under normal conditions, the form of nitrogen may affect the performance of sugar beet plants under abiotic stress, particularly salinity. Additionally, exploring the most appropriate type of nitrogen for sugar beet could mean optimizing sucrose content. Therefore, here using two lines, sugar beet was grown in pots (filled with 4 kg soil), salt-resistance (line 7233- p.29 x Mst), and salt-sensitive (line 3929-21939), the effect of two different forms of nitrate in the form of calcium nitrate (1 g per pot) and ammonium in the form of ammonium sulfate (1 g per pot) under normal and salt stress condition (40 Millimoles per liter sodium chloride) were evaluated. The result revealed the positive influence of nitrate over ammonium by indicating higher dry weight in both sensitive line: 19.2 and 13.6 g, and tolerance line: 20.4 and 13.6 g, respectively alone and in combination with salinity stress. Similarly, root yield levels positively influenced by nitrate treatment either alone or under salinity stress (sensitive line: 194.5 and 243.2 g and tolerance line: 207 and 249.5 g). The outcomes additionally showed the accumulation of proline aerial parts in both lines, and however, the proline accumulation of sensitive line was higher (3.9 mg/g dry weight). Moreover, induction of proline aggregation was considerably higher in nitrate nitrogen-treated sensitive line (9.3 mg/g dry weight). The absence of significant difference was obseved between nitrogen treatments in terms of extractable sucrose and root molasses sugar. Also, the root impurities increased in those treated with nitrate-nitrogen and salinity. It can be concluded that nitrate-nitrogen has improved the performance of both sugar beet lines against salinity stress, and its practical application is adviseable.

Background: A crucial aspect of electrochemical enzymatic biosensor development is the immobilization of the enzymes, as it directly influences the sensitivity of the bioelectrode. Among the different methods used to incorporate enzymes on the surface of the transducers, layer-by-layer (LbL) self-assembly based on electrostatic interaction with polyelectrolytes of opposite charge stands out due to its simplicity and reproducibility. Aims: The aim of the work was to develop an electrochemical glucose biosensor by LbL assembly of a new functionalized chitosan polycation and the enzyme glucose oxidase (GOx). Methods: Chitosan was chemically functionalized with glucose by the Maillard reaction. The resulting polycation, named G-Chit, is soluble in the medium compatible with the enzyme. The bioelectrode was obtained by alternating adsorption of G-Chit and GOx onto carbon paste electrodes. By selecting the number of bilayer of G-Chit/GOX, the enzyme concentration, and the pH, the electroanalytical performance of the biosensor was optimized. The electrochemical responses were characterized by cyclic voltammetry and chronoamperometry. Results: Under optimized experimental conditions, the biosensor exhibited a sensitivity of (0.81 ± 0.03) µA mM-1 in a glucose concentration range of (0.18 to 1.75) mM. Discussion: Results indicated that catalytic response increases both with the number of G-Chit/GOx bilayers and the enzyme concentration, obtaining the best responses for 3 bilayers and 2 mg mL-1, respectively, while the optimum working pH value was 7.0. Conclusions: The analytical response of the biosensor was tested in milk samples with negligible matrix effects, suggesting a potential application in other dairy products. Results show that G-Chit appears promising for the immobilization of enzymes.