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•Subchronic intoxications were induced in male rats by repeated IP injections of lead acetate and/or cadmium chloride.•Right ventricle trabecules and papillary muscle preparations ...were used for modeling the heart cycle.•Single twitch parameters in trabecules and papillary muscles respond to the intoxications differently.•Intoxications with Pb and Cd led to contra-directional effects on some mechanical parameters and the myosin isoform ratio.•Background administration of bioprotectors attenuated cardio-mechanical effects of Pb + Cd intoxication.
Subchronic intoxications induced in male rats by repeated intraperitoneal injections of lead acetate and cadmium chloride, administered either alone or in combination, are shown to affect the biochemical, cytological and morphometric parameters of blood, liver, heart and kidneys. The single twitch parameters of myocardial trabecular and papillary muscle preparations were measured in the isometric regime to identify changes in the heterometric (length-force) and chronoinotropic (frequency-force) contractility regulation systems. Differences in the responses of these systems in trabecules and papillary muscles to the above intoxications are shown. A number of myocardium mechanical characteristics changing in rats under the effect of a combined lead-cadmium intoxication and increased proportion of α-myosin heavy chains were observed to normalize fully or partially if such intoxication was induced against background administration of a proposed bioprotective complex. Based on the experimental results and literature data, some assumptions are suggested concerning the mechanisms of the cardiotoxic effects produced by lead and cadmium.
In addition to the current BGO-OD experimental program we propose to study nuclear media effects in photoproduction of mesons using a new experimental method based on measuring a recoil nucleon as a ...tagger of the selected partial channel. The principal goal is to learn how unstable mesons (
π
o
, π
+
,
π
−
,
η, ρ, ω
, etc.) interact with nuclear media. This approach continues previous GRAAL experiments to study nuclear excitation dynamics, including multifragmentation of nuclei by intermediate energy photons.
The physical reasons for observing the splitting of optical lines several orders of magnitude smaller than the spectral width of a laser pulse are investigated. A theory of coherent and incoherent ...photon echo (PE) in an external static magnetic field and in the presence of a pulsed magnetic field, which causes oscillations of the PE intensity, is elaborated. It is shown that the periods of oscillations in the echo intensity, the echo duration, and the dimensions of the regions in the inhomogeneous line, where the excited ions are coherent, do not depend on the degree of coherence of the laser pulse and on the external static magnetic field. As follows from the theory, in the case of the coherent excitation of the echo, the amplitude of the intensity oscillations is independent of the external static magnetic field if the inhomogeneous line is symmetric. It is shown that the amplitude of the oscillations at the incoherent excitation of the echo is equal to the autocorrelation function of the distribution function of the transition frequency along the inhomogeneous line with the argument equal to the Zeeman splitting of the optical line in the external magnetic field. In this case, the experimental values of the oscillation amplitude are in good agreement with the calculated values of the autocorrelation function for the total inhomogeneous line in LuLiF
4
:Er
3+
(
4
I
15/2
⇒F
9/2
transition). In the same way, the autocorrelation function has been obtained for YLiF
4
:Er
3+
on the same transition.
A novel scheme for determining the pseudo-Stark splitting of optical lines has been suggested and tested in experiment. The scheme allows one to observe the beating of a photon echo waveform under ...conditions of overlap in time between a weak electric pulse and its echo-pulse. The pseudo-Stark splitting is equal to the inverse average modulation period of the echo waveform. The photon echo beating of the R1-line in Ruby has been observed. The dependence of the inverse average modulation period of the echo waveform on the average value of the electric field over the optically excited volume has been found. The obtained values of the pseudo-Stark parameter are in good agreement with known literature data.
A method for testing threshold SiO
-aerogel Cherenkov detectors using cosmic radiation is described. The implementation requires a minimal amount of additional electronics and does not involve ...massive absorber layers (such as lead, etc.). The method allows for accurate determination of the efficiency of the investigated detectors and for the study of the detectors’ operation in different energy intervals for relativistic particles.
A new scheme of the definition of g-factors as ground and excited optical states of a paramagnetic ion in zero external constant magnetic field has been proposed and experimentally realized in ...optical systems in which the Zeeman effect is manifested. A pulse of a weak magnetic field leads to the occurrence of relative phase shifts of the excited dipoles and, as a consequence, to modulation of a photon echo wave form if the magnetic pulse overlaps in time with the echo pulse. The modulation periods of the wave form depend on polarization of the laser light which excites the photon echo. The values of these periods for σ - and π-laser light polarization have been measured and then the g-factors of the ground 4I15/2 and excited 4F9/2 states of the Er3+ ion in the LuLiF4 and the YLiF4 matrices have been determined. The g-factor values have been compared with the known literary data.
Purpose Analyze the various methods for determining the monitor doses in neutron therapy using the U-120 cyclotron and to choose the monitoring method that provides the highest accuracy in dose ...delivery to the tumor.
Material and methods The distributions of the absorbed dose of the therapeutic beam from the U-120 cyclotron were measured in a tissue-equivalent medium using the differential method, in which two ionization chambers with different sensitivity to neutron radiation were used. A comparison of radiation effects on tissues using various techniques of determining the monitor doses was made. The linear-quadratic model was used to assess responses to ionizing radiation.
Results Dosimetry studies revealed that the therapeutic beam of the U-120 cyclotron contains concomitant gamma radiation, the contribution of which to the total neutron-photon dose increases with increasing depth of the irradiated medium. The presence of gamma radiation in the neutron beam dictate the need to find the correct method for monitoring neutron therapy. A comparison of radiation effects on the tumor tissue using different techniques of determining the monitor doses was made. It was found that at equal neutron-photon doses, the neutron dose in the tumor changed depending on its depth. It can lead to an incorrect conclusion about the effectiveness of neutron therapy depending on a single dose as well as in relation to various dose fractionation schedules.
Conclusion The analysis of the results obtained showed that the problem can be most accurately solved using a technique in which the monitor coefficient and monitor doses are determined from the distribution of the neutron dose, taking into account the contribution of the gamma radiation dose to the total neutron-photon dose.
The coefficient of a linear Stark shift of the 4F9/2-4I15/2 transition of Er3+ ion in Y2SiO5 is measured (14.3 kHz V−1 cm) by splitting the upper and lower levels of the transition by a pulsed ...electric field and measuring the splitting frequency from the period of beatings of the temporal form of a photon echo signal (stark photon echo beating method). The linear Stark coefficients of Er3+ transitions in Y2SiO5 have not been measured before, and this is a valuable result for a number of applications such as gradient echo memory, group velocity control via spectral hole burning, etc.
An ultra high-resolution optical spectroscopy technique is proposed for measuring Zeeman and pseudo-Stark frequency splitting during optical transitions. This approach uses the change in the time ...shape of the echo signal upon a a weak pulse perturbation that splits the optical transition frequencies of two or more echo-active ion subgroups.
Optimization of dose fractionation regimens is an important way to increase the effectiveness of radiotherapy for malignant tumors. To choose the optimal radiotherapy regimen, it is necessary to know ...the nature of tumor regression in different dose fractionation schedules. The purpose of the study was to analyze the patterns of tumor regression in various dose fractionation regimens, while having the same level of normal tissue damage in cases when damage to normal and tumor tissues can be described using the lineal quadratic model. Material and methods. We developed the algorithm for calculating survival of tumor cells under dose fractionation regimes resulting in the same degree of damage to normal tissue. Using this algorithm, the tumor regression patterns were found at various quantitative ratios between the radiosensitivities of the normal and tumor tissues. Results. It was found that in the case of equality of the ratios of radiobiological parameters characterizing the tumor and normal tissues (αt /βt =αn /βn ), the efficacy of radiation therapy did not depend on the dose fractionation regimen at any ratio between the radiosensitivities of the tumor and normal tissues. In the case of , the efficacy of radiation therapy depended on the dose fractionation regimen and increased with decreasing the dose per fraction. On the contrary, in the case of , the efficacy of radiation therapy increased with increasing a single dose. Our theoretical results were consistent with other recent studies.
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