Laser-accelerated protons using density gradients in hydrogen plasma spheres

The effect of different density profiles on micron-sized hydrogen plasma spheres is investigated when the plasma gets irradiated with an ultrashort circularly polarized laser. In this study, we show that significant improvement in the characteristics of the accelerated protons viz. maximum proton energy, as well as their monoenergetic behaviour, is possible by using a plasma sphere having a tailored density profile. A linear-shaped density inhomogeneity is introduced in the plasma sphere such that the density is peaked at the centre and gradually dropping outwards. The density gradient is tuned by changing the peak density at the centre. The optimum regime of steepness is found for the maximum energy attained by the protons where the target is opaque enough for the radiation pressure to play its role, however not too opaque to inhibit efficient target heating. A novel Gaussian-shaped density profile is suggested which plays an important role in suppressing the sheath field. With a decreased rear-side field, a visible improvement of the monoenergetic feature of the protons is observed.

Methodological approaches to prevention of radiation-induced skin reactions in neutron-photon therapy for malignant neoplasms

The goal of radiotherapy is to maximize the radiation dose to abnormal cancer cells while preventing damage to healthy tissue. in neutron therapy, the optimum regime of treatment is uncertain to date.The purpose of the study to develop a set of methodological approaches that ensure the permissible frequency and severity of radiation-induced reactions in cancer patients subjected to neutron and neutron-photon therapy (NFt) using u-120 cyclotron.Material and methods. We used the dependence of the relative biological effectiveness (RBE) of neutrons on the dose and time-dose-fractionation model (tdF). the interaction of neutrons with various types of tissues was analyzed, and the algorithm for summing neutron and photon doses in neutronphoton therapy was developed.Results. Clinical studies of neutron-photon therapy showed that the developed approaches can predict and prevent serious damage to normal tissue with a satisfactory accuracy. the role of all factors influencing the nature of radiation reactions was taken into account in the computer program, which allowed the main characteristics of the planned courses of neutron-photon therapy to be obtained.

Влияние содержания корунда и температуры спекания на механические свойства керамических композитов CaO-ZrO-=SUB=-2-=/SUB=--Al-=SUB=-2-=/SUB=-O-=SUB=-3-=/SUB=-

We have studied the mechanical properties (Vickers microhardness H _V and fracture toughness K _C) of nanostructured CaO–ZrO_2–Al_2O_3 ceramic composites as dependent on the content of corundum (0 ≤ $$C_{Al_{2}O_{3}}$$ C A l 2 O 3 ≤ 25%) and the temperature of sintering (1250°C ≤ T _1 ≤ 1500°C). Optimum value of the corundum content ( $$C_{Al_{2}O_{3}}$$ C A l 2 O 3 = 5%) and optimum regime ( T _1 = 1300°C, 5 min; T _2 = 1200°C, 4 h) of two-stage sintering are established, which favor attaining the best mechanical characteristics of ceramic composites ( H _V = 12.25 GPa, K _C = 8.47 MPa m^1/2).

INTEGRATED SYNOPTICAL METHOD FOR CALCULATING ASSIMILATION CAPACITY OF SEA WATERS

Pollution of sea waters is one of major attributes of coastal industrial centers and the norming of such emissions is one of major countermeasures. The assimilation capacity of sea waters is a major factor relevant at norming and planning of outflows into sea waters. At present time the synoptical method has been developed, which doesn’t require carrying out long time and repeated observing of the level of pollution of sea waters. This method has formed the basis for developing the integrated synoptical method for calculating sea water assimilation capacity. The suggested method provides for division of the sea waters into separated homogenous water masses. The aim of the study is to develop an inverse integrated synoptical method allowing synthesizing of such an optimum order for loading separate water masses with pollutants upon, at which the calculated total value of assimilation capacity would reach its maximum. The article shows the possibility of utilization of known synoptical method for determining assimilation capacity of sea waters in the inverse order, i.e. for calculating the maximum value of pollutant put into the fixed zone of sea waters, upon a condition of reaching the given amount of assimilation capacity and absence of essential negative effect on ecosystem. The task of calculating an optimum regime function of discrete type, upon which the integrated value of assimilation capacity would reach the maximum value, has been formulated. The solution of analogue equivalent of the formed optimization task is carried out using the Euler equation for a non-conditional variation optimization task, taking into account the accepted limitation condition. The recommendations on optimum loading of different sea water zones with determined type of pollutant have been given.

Generalized Model of Atmospheric Aerosol for Optimal Processing of Remote In-process Control Colorimeter Signals

The paper briefly surveys regime functions of colorimetric systems and their realization featured by necessity to calculate the correlation between color channels’ signals. It suggests a generalized model of optical depth of atmospheric aerosol, which could be used to form the target functional for optimization of correlation calculator of color signals. The optimum regime of carrying out correlation calculations based upon the atmospheric factors is synthesizedas a result of optimization of the considered model of colorimeter.

Magnetic Drug Targeting in Partly Occluded Blood Vessels Using Magnetic Microspheres

Magnetic drug targeting can be used for treating stenosis and thrombosis in partly occluded blood vessels. Herein, a numerical investigation of magnetic drug targeting using functionalized magnetic microspheres in partly occluded blood vessels is conducted. An Eulerian-Lagrangian technique is adopted to resolve the hemodynamic flow and the motion of the magnetic particles in the flow. An implantable cylindrical permanent magnet insert is used to create the requisite magnetic field. Targeted transport of the magnetic particles in a partly occluded vessel differs distinctly from the same in a regular unblocked vessel. Parametric investigation is conducted, and the influence of the flow Re, magnetic insert diameter, and its radial and axial position on the “targeting efficiency” is reported. Analysis shows that there exists an optimum regime of operating parameters for which deposition of the drug-carrying magnetic particles in a predesignated target zone on the partly occluded vessel wall can be maximized. The results provide useful design bases for an in vitro setup for the investigation of magnetic drug targeting in stenosed blood vessels.