Optical methods and electron microscopy have been used to determine the size distribution and complex refractive index of magnetite (Fe 3 O 4 ) particles. The particles were synthesized as a component of magnetically controlled pills. The proposed algorithm for experimental data processing is intended for nano particle sizes from 1 to 100 nm.

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The problem of corrosion resistance of medical instruments is rather urgent. In addition to aesthetic characteristics, corrosion deteriorates functional parameters of medical instruments. The cutting and cleaving edges of the instruments become blunted. In extreme cases, corrosion may cause complete destruction of medical instruments, which is particularly dangerous during surgical operations.Medical instruments are mainly exposed to corrosive medium during chemical disinfection, presterilization cleaning, and sterilization. Chemical methods cannot be avoided completely because certain materials used in medical instruments do not withstand thermal sterilization.Therefore, development of new sterilization solutions with reduced corrosion activity to the materials used in medical instruments is of considerable practical importance.The goal of this work was to comparatively characterize corrosion activities of various disinfection solutions: and Pervomur [3]) and newly developed (Nebis [6] and Peronix [2]). TheNebis solution is based on diperoxyadipic acid, whereas the Peronix solution is a water-tretbutanol mixture of monoperoxycarbonic acids C7-C 9.Tests were carried out with samples of 12Cr18Ni10T and 4Cr13 metals (the first group of metals by OST 25.1-005-87 [5]). This group of metals withstand all methods of ster/2ization, which supports the correctness of the comparison.Corrosion activity of solutions was assessed by the method of fast electrochemical testing by two criteria: steady-state corrosion potential (Eeor) and kinematic characteristics of polarization curves (l--E). In addition, corrosion resistance was tested by the method of complete immersion of samples into aggressive media with further visual inspection and gravimetric analysis from the following equation:where V is the mean rate of corrosion averaged over the test period, mg/cm 2-h; Am is the corrosion losses, rag; S is the sample surface area, cruZ; ~ is the test time, h. Test samples were preliminarily prepared by a standard method [7]. Electrochemical tests were performed in a glass cell YaSE-2 using a PI-50-1.1 potemiostat and a chart recorder PDA1. The test samples were polarized in a potentiometric mode with a sweep rate of 1 mV/sec. An Ag/AgCI electrode EVLIM3.1 was used as a reference electrode. Potentials were measured relative to a standard hydrogen electrode.Experimental results were processed within the framework of the following assumptions. Steady-state corrosion potentials Eco r (Table 1) characterize the fundamental possibility of metal corrosion to occur in the tested system. According to this test, the Cr-Ni steel 12CrlSNi10T demonstrates higher corrosion resistance than the Cr steel 4Cr13 because the mean potential of the former is 0.2-0.3 V more positive than the mean potential of the latter. However, corrosion potentials do not represent the extent of aggression of different test solutions against specific metals because the partial pressure of O 2 and H 2 contributes to the cathode reaction. These values depend on solution ...