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Actin is one of the most abundant proteins in nature. It is found in all eukaryotes and plays a fundamental role in many diverse and dynamic cellular processes. Also, actin is one of the most ubiquitous proteins because actin‐like proteins have recently been identified in bacteria. Actin filament (F‐actin) is a highly dynamic structure that can exist in different conformational states, and transitions between these states may be important in cytoskeletal dynamics and cell motility. These transitions can be modulated by various factors causing the stabilization or destabilization of actin filaments. In this review, we look at actin stabilization and destabilization as expressed by changes in the thermal stability of actin; specifically, we summarize and analyze the existing data on the thermal unfolding of actin as measured by differential scanning calorimetry. We also analyze in vitro data on the heat‐induced aggregation of actin, the process that normally accompanies actin thermal denaturation. In this respect, we focus on the effects of small heat shock proteins, which can prevent the aggregation of thermally denatured actin with no effect on actin thermal unfolding. As a result, we have proposed a mechanism describing the thermal denaturation and aggregation of F‐actin. This mechanism explains some of the special features of the thermal unfolding of actin filaments, including the effects of their stabilization and destabilization; it can also explain how small heat shock proteins protect the actin cytoskeleton from damage caused by the accumulation of large insoluble aggregates under heat shock conditions.

We have applied differential scanning calorimetry to investigate thermal unfolding of F-actin. It has been shown that the thermal stability of F-actin strongly depends on ADP concentration. The transition temperature, T(m), increases with increasing ADP concentration up to 1 mM. The T(m) value also depends on the concentration of F-actin: it increases by almost 3 degrees C as the F-actin concentration is increased from 0.5 to 2.0 mg/ml. Similar dependence of the T(m) value on protein concentration was demonstrated for F-actin stabilized by phalloidin, whereas it was much less pronounced in the presence of AlF4(-). However, T(m) was independent of protein concentration in the case of monomeric G-actin. The results suggest that at least two reversible stages precede irreversible thermal denaturation of F-actin; one of them is dissociation of ADP from actin subunits, and another is dissociation of subunits from the ends of actin filaments. The model explains why unfolding of F-actin depends on both ADP and protein concentration.

The goal of the work is to make a comparative analysis of the luminance, efficiency, and lifetime of some green and blue phosphors based on (Zn,Mg)O, ZnOLi20-Ba203, ZnGa204, ZnS etc.The optimal synthesis conditions for the ZnGa204:Mn phosphor have been designed. The CL efficiency of this phosphor has been found to reach 0.8 lm/W in the range 100-1000 eV. When excitation density is below 1 WIcm2, the luminance decrease does not exceed 10% per 2000 hours in the stationary mode as well as in the pulse one. Addition of some aluminum and ammonium halogenides at manganese activation raises efficiency up to 1 1".It should be noted that the efficiency drop of the green ZnS:Cu,Al phosphor is above 45-50% with other conditions being equal.A blue Z~G~~O~+ ( L~O . S G~O . S )~. Z~O . S G~~O~ phosphor was synthesized. Replacement of half zinc atoms by lithium and gallium atoms leads to an increase in CL efficiency up to 0.2 lm/W, doping with titanium improves the purity of colour. The blue ZnS:Ag,Cl phosphor at the mentioned excitation conditions looses up to 70% of its luminance during 2,000 hours (the stationary mode) while the oxide phosphor remains resistant to electron bombardment.A comparative study was made of the volt-ampere and volt-luminance curves of the green and blue phosphors based on oxide and sulphide matrices in pilot VFDs. The effect of saturation is shown to be mainly peculiar to the sulphide phosphors and to be dependent on the activator concentration and the content of the conductive additive In203 in CL screens in VFDs.