Photodynamic inactivation of isolated crayfish mechanoreceptor neuron: different death modes under different photosensitizer concentrations

To study the mechanism of photodynamic nerve cell killing, isolated crayfish mechanoreceptor neurons were photosensitized by the sulfonated aluminum ophthalocyanine Photosens. Neuron activity was continuously recorded until irreversible abolition. Intense (10(-5) M Photosens) or weak (10(-7) M Photosens) photosensitization induced different bioelectric neuron responses: firing activation followed by irreversible depolarization block or gradual inhibition until firing abolition, respectively. These bioelectric responses were accompanied by different biochemical and morphological changes. In the case of intense photosensitization, neuron nuclei swelled and then shrank. Succinate dehydrogenase (SDH) was inhibited, and the plasma membrane was compromised just after firing cessation. Weak photosensitization did not induce these changes but caused swelling of the endoplasmic reticulum and destruction of the matrix, cristae and membranes in some of the mitochondria. Other mitochondria, however, retained the normal structure. Plasma membrane damage, SDH inhibition, nucleus shrinkage and impairment of the nuclear border occurred after 2-4 h. It is concluded that intense photosensitization induced necrotic processes during irradiation, whereas weaker impact caused delayed necrosis 2-4 h later. The observed electrophysiological neuron responses to photodynamic therapy may be considered as early hallmarks of different modes of forthcoming cell death.     

Effective Synthesis of β-Ketophosphonate Derivatives of Calix[4]resorcinolarenes

An effective method for introduction of -phosphonate fragments to a calix[4]resorcinolarene matrix is presented octa(ketophosphonate)calix[4]resorcinolarenes are prepared. The effectiveness of 2,8,14,20-tetramethyl-4,6,10,12,16,18,22,24-octa[3-(dimethoxyphosphoryl)-2-oxopropyl]calix[4]-resorcinolarene for extraction of lanthanum ions from water to chloroform in the presence of picrate ions, accompanied by formation of a complex is demonstrated.     

Luminescence properties of acridine dyes in micellar sodium dodecyl sulfate solutions containing thallium ions

The effect of external heavy Tl^I ion on the luminescence properties of Trypaflavine, Acridine Yellow, and Acridine Orange solubilized in sodium dodecyl sulfate micelles was studied. An increase in the concentration of thallium ions results in a decrease in the intensity of prompt fluorescence, an increase in the intensity of delayed fluorescence, the appearance of phosphorescence at 20 °C, and a shortening of the triplet state lifetime of the dyes. The effective and micellar Stern—Volmer constants of fluorescence quenching of the dyes by thallium ions were determined. The effective and micellar quenching rate constants of triplet states of the dyes by Tl(i) ions and lifetimes of the triplet states of the dyes in the absence of thallium ions were calculated on the basis of kinetic measurements.     

Investigation of the dynamic characteristics of composites

The dynamic characteristics E and G and the damping capacity δ* of polymeric resins and composites based on glass, carbon, and boron fibers have been investigated. It is shown that the mechanical losses are correlated with the modulus of elasticity and the shear modulus of the resin and composites with different types of reinforcement. The vibrational strength of various structural materials is estimated.     

Synthesis,phase formation,and properties of nanomaterials based on the titanium dioxide−iron(III) oxide binary system

The properties of nanomaterials based on the titanium dioxide?iron(III) oxide binary system prepared by low-temperature coprecipitation from aqueous solutions are studied. The effect of thermal treatment conditions and other factors on the process of phase formation and the properties of the synthesized products is examined. It is demonstrated that these materials have a relatively low photocatalytic activity but a high sorption capacity.     

Features of the ELF/VLF Wave Generation and Propagation Processes during Ionospheric Modulated High-Frequency Heating

Radiophysics and Quantum Electronics - We consider the results of observations of the ELF/VLF horizontal magnetic field of the ionospheric source using a high-latitude network of PGI stations in...     

Asymptotics of the trajectory of an interval that contains the preimage of a periodic point

We consider dynamical systems defined by continuous maps of an interval I of the real axis into itself. We prove that if an interval J in I contains the preimage of a periodic point of period p of a map f ∈ C ⁰(I, I), then the sequence of intervals f ^2pn (J), n= 0, 1, 2,…, is convergent. Translated from Neliniini Kolyvannya, Vol. 12, No. 1, pp. 130–133, January–March, 2009.     

Dynamic Shear Model for Layered Plates

A variant of a geometrically nonlinear dynamic shear model for layered plates is offered, where the inertial forces are taken into account at the stage of formation of hypotheses. A closed-form solution to the problem of forced vibrations is obtained for layered plates clamped or hinge-supported on their contour. The amplitude-frequency characteristics for various kinds of external loads are constructed. The influence of layer distribution across the package thickness is analyzed.     

Stability of the critical behavior of weakly disordered systems against replica symmetry breaking

A field-theoretical approach is used to describe the critical behavior of weakly disordered systems with a p-component order parameter. Renormalization group (RG) analysis of the effective replica Hamiltonian of a model with replica-unsymmetrical interaction potential is carried out in a two-loop approximation directly for three-dimensional systems. The Padé-Borel summation technique is used to determine fixed points of the RG equations for the case of a single-step replica symmetry breaking (RSB). Analysis of their stability showed that the type of stable critical behavior of the disordered systems against the RSB effects remains as before.