Gadolinium neutron capture therapy (GdNCT) is used for treatment of radioresistant malignant tumors. The absorbed dose in GdNCT can be divided into four primary dose components: thermal neutron, fast neutron, photon and natural gadolinium doses. The most signi cant is the dose created by natural gadolinium. The amount of gadolinium at the irradiated region is changeable and depends on the gadolinium delivery agent and on the structure of the location where the agent is injected. To dene the time dependence of the gadolinium concentration ρ(t) in the irradiated region the pharmacokinetics of gadolinium delivery agent (Magnevist) was studied at intratumoral injection in mice and intramuscular injection in rats. A polynomial approximation was applied to the experimental data and the in uence of ρ(t) on the relative change of the absorbed dose of gadolinium was studied.
Abstract:In the present work, based on publications dedicated to nat Gd natural gadolinium isotopes, characteristics of secondary particles are analysed in details for various neutron-induced reactions. Characteristics of the secondary particles produced in these reactions that make significant contribution to absorbed dose are estimated. It is also established that the main contribution to the absorbed dose is made by secondary particles produced in interactions of neutrons and 155 Gd and 157 Gd isotopes. From comparison of gamma-radiation spectra it is defined that the amount of -quanta with energies 0-400 keV (i.e. effective -quanta) produced in the (n,)-reaction by 155 Gd is higher than that by 157 Gd. Compared spectra of other particles (internal conversion electrons, Auger electrons,
The paper presents the results of studies on the production of thin-layer nanofiber non-woven materials based on silk fibroin and acrylonitrile copolymer by the electrospinning method. The dependence of anisotropy characterizing the structural states of the obtained thin-layer polymeric materials on deformation effects, their sorption and filtration properties has been studied. The broad possibility of using nanofiber nonwoven materials as nanofilters and the efficiency of the filtration process of nonwoven materials with an increase in the size of their nanopores are shown.Keywords: Polymer, Silk Fibroin, Acrylonitrile Copolymer, Electrospinning, Isotropic, Anisotropic, Orientation, Nanofiber, Nanomaterial, Formation, Structure, Deformation, Nanofilter.
An algorithm based on the spectral-difference method for numerical solution of the dynamic problem for porous media is proposed. We consider a linear two-dimensional problem in the form of dynamic equations in terms of displacement components described by three elastic parameters. The governing equations are based on conservation laws and consistent with the thermodynamics conditions. The medium is assumed to be isotropic and two-dimensional-inhomogeneous with respect to the spatial coordinates. To numerically solve the problem, we propose a method based on the joint use of the Laguerre integral transformation with respect to time and the finite difference approximation with respect to spatial coordinates. A description of the numerical implementation of the proposed method is given and its features are analyzed in the calculations. The efficiency of applying the Laguerre transformation and its difference from the Fourier transform for solving the direct dynamic seismic problems is discussed. Numerical results of the simulation of the seismic wave propagation fields for the test medium model are presented.
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