Kinetic parameters of the reaction of isobornylphenols with peroxy radicals

The stoichiometric factors of inhibition and the rate constants (k ₇) were measured for the reaction of isobornylphenols with peroxy radicals of ethylbenzene. The values of k ₇ of the compounds under study increase with an increase in the amount of alkyl substituents and OH groups on the aromatic ring. The introduction of the oxygen atom between the o-isobornyl substituent and the aromatic ring decreases k ₇ by a factor of 6.5. The inhibiting action of binary mixtures of sterically hindered phenols with 2-isobornyl-4-methylphenol and 2,6-diisobornyl-4-methylphenol in the initiated oxidation of ethylbenzene is close to additive.     

Contrast-Free FLIM Reveals Metabolic Changes in Pathological Islets of Langerhans

FLIM (Fluorescence Lifetime Imaging Microscopy) is a powerful tool that could be used in the future to diagnose islet cell recovery after therapy. The identification of appropriate FLIM parameters is required to determine islet quality and islet cell metabolism throughout the organ under various conditions of insulin deficiency. The aim of the work was to identify key FLIM parameters, changes of which are characteristic of pancreatic pathologies. The τm, τ1, τ2, α1, α2 and α1/α2 of free and bound forms of NAD(P)H of the islet cells of animals (rats and pigs) and of humans with and without pathologies were measured and analyzed. The data were confirmed by IHC and histological studies. We identified three FLIM parameters in islet cells from animals with streptozotocin (STZ)-induced diabetes mellitus (DM) and from humans with chronic pancreatitis + type 2 diabetes (T2D), which differ in the same way: τm and α2 take lower values compared to the nonpathological islet cells, while α1/α2 takes higher values. In islet cells from patients with adenocarcinoma (PDAC) and chronic pancreatitis, these parameters had reverse tendency relative to the norm or did not differ. Thus, minimally invasive and non-contrast FLIM methods may, in the future, be used to diagnose pathological islet cells.     

Neutron-kinetic code validation against measurements in the Moscow V-1000 zero-power facility

Measurements carried out in an original-size VVER-1000 mock-up (V-1000 facility, Kurchatov Institute, Moscow) were used for the validation of three-dimensional neutron-kinetic codes, designed for VVER safety calculations. The significant neutron flux tilt measured in the V-1000 core, which is caused only by radial-reflector asymmetries, was successfully modeled. A good agreement between calculated and measured steady-state powers has been achieved, for relative assembly powers and inner-assembly pin power distributions. Calculated effective multiplication factors exceed unity in all cases. The time behaviour of local powers, measured during two transients that were initiated by control rod moving in a slightly super-critical core, has been well simulated by the neutron-kinetic codes.     

Numerical simulation of structure transformation processes as the basis for regulating the properties of nanodisperse composition systems and materials

Using computer simulations, the regularities of structure formation in disperse systems under dynamic conditions that predetermine the nature of the structure formed and, hence, the properties of obtained nanodisperse composition materials (materials with a nanodisperse component) are considered. Phenomena of the appearance and the development of a macroscopic structural heterogeneity, namely, the break in continuity of the structure in highly concentrated systems are reproduced, as are the conditions for the removing the break using surface active substances and vibrational impacts, which allows one to control the properties of disperse materials synthesized based on highly disperse solid phases.     

Radiation consequences of seawater contamination during floating storage of reactor-compartment units from salvaged nuclear-powered submarines

The storage time before salvaging of decommissioned nuclear-powered submarines and the floating storage time of reactor units from salvaged submarines can total decades. During this time, radioactive contamination of seawater occurs as a result of the corrosion of the pressure hull in the region of the reactor system and rupturing of the pressure hull - as a result of corrosion of the components of the reactor system. A computational analysis shows that under standard storage conditions the specific activity of water is 10⁵–10⁶ times lower than the intervention level. In the case when the hull and the reactor system are destroyed even with remaining fuel, the specific activity of the sea water near the point of sinking also does not exceed the intervention level because of the slow emission of fission products and transuranium nuclides.Translated from Atomnaya Énergiya, Vol. 97, No. 3, pp. 210–218, September, 2004.     

Solving the Problems of High-Temperature Sulfur Corrosion in Primary Oil Refineries

Chemistry and Technology of Fuels and Oils - This article examines the effect of natural sulfur-containing oil compounds on the corrosion state of plant. It states that the main reason for the...