Using the simultaneous readings of the left ventricular remodeling model and the left ventricular weight to body weight ratio, the Gaasch and Zile classification was able to distinguish almost ...completely (95%) the dogs without pulmonary edema from those with pulmonary edema in cases of MMVD (myxomatous mitral valve disease) with an established limit for the left ventricular mass of 7.478 g/kg between the two groups. In one of the twenty animals surveyed, the classification failed. We assume that this is related to the exacerbation of the disease and the change of its chronic course due to an additional cause.
This article provides relevant information on the catalysts’ morphological characteristics that allow for the optimal combination of activity and durability of the materials for proton-exchange ...membrane fuel cells. The home-made Pt/C and PtCu/C catalysts have been established to have at least by 20% higher values of the mass activity in the oxygen reduction reaction than the commercial Pt/C analogue (HiSPEC 3000, Johnson Matthey). The detailed analysis of the microstructure by transmission electron microscopy and the electrochemical parameters by electrochemical surface-sensitive methods after the stress testing has allowed estimating the contribution of various mechanisms to the degradation process. After the stress testing, the residual activity in the oxygen reduction reaction of the home-made materials has proved to be at least more than double that of the commercial Pt/C catalyst. A specific feature of this work is the presented correlation between the morphology and the electrochemical behavior of the catalysts, with this interconnection appearing to be a valuable resource for a wide range of scientists.
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•The rapid and facile synthesis methods of the highly active catalysts are presented.•The PtCu/C catalyst is 2.5 times more active in the ORR than the commercial Pt/C.•The testing is conducted within the protocols with the long-term cycling and the potential hold.•The home-made materials are more robust against degradation than the commercial one.•The integrated approach to studying the catalysts' durability is presented.
Aim.
The paper proposes approaches to the organisation of testing of digital systems through malfunction imitation for the purpose of ensuring compliance of international and Russian failure and ...fault resistance standards for the purpose of efficient (in terms of time) detection of software defects as part of mass production of products. The paper proposes a structure and operating algorithm of a hardware and software test bed for malfunction simulation intended for testing a system’s devices. The test bed collects and processes data for fuzzing, hardware error identification, as well as defines the scope of testing.
Methods
. The paper used basic systems approach, classical methods of the probability theory and mathematical statistics, decision theory, methods of hardware and software testing and development, mathematical theory of fuzzy sets and fuzzy logic.
Results.
Malfunction simulation algorithms were developed for the purpose of testing hardware and software systems using fuzzing that ensure probabilistic estimation of the termination time of testing with a specified accuracy.
Conclusions.
The above set of algorithms allows detecting system defects in the process of software and hardware integration into a single system that cause new malfunctions (emergence) that cannot be taken into consideration at the design stage.
A synthetic photonic lattice (SPL) is a re-configurable test-bed for studying the dynamics of one-dimensional mesh lattices including the photonic implementations of discrete time quantum walks. ...Unlike other realizations of photonic lattices, SPL possesses easy and fast control of lattice parameters. Here we consider disordered SPL where the coupling ratio between the two fiber loops realizing the lattice is random but does not change between the round trips. We obtain a new analytical result for the localization length (inverse Lyapunov exponent) for a practical case of weak coupling disorder. We also numerically study the dynamics of the pulse train circulating within the loops and observe that despite delocalization transition at the band center the pulse spreading is arrested even at small values of the disorder.
The subject of mathematical study and modelling in this paper is an inbound call center that receives calls initiated by customers. A closed exponential queueing network with customer retrials and ...impatient customers is used as a stochastic model of call processing. A brief review of published results on the application of queueing models in the mathematical modeling of customer service processes in call centers is discussed. The network model is described. The possible customer states, customer routing, parameters, and customer service features are given. The allocation of customers by network nodes at a fixed time fully describes the situation in the call center at that time. The state of the network model under study is represented by a continuous-time Markov chain on finite state space. The model is studied in the asymptotic case under the critical assumption of a large number of customers in the queueing network. The mathematical approach used makes it possible to use the passage to the limit from a Markov chain to a continuous-state Markov process. It is proved that the probability density function of the model state process satisfies the Fokker - Planck - Kolmogorov equation. Using the drift coefficients of the Fokker - Planck - Kolmogorov equation, a system of ordinary differential equations for calculating the expected number of customers in each network node over time can be written. The solution of this system allows for predicting the dynamics of the expected number of customers at the model nodes and regulating the parameters of the call center operation. The asymptotic technique used is applicable both in transient and steady states. The areas of implementation of research results are the design of call centers and the analysis of their workload.
This paper shows how bubbling the reaction medium with CO affects the nucleation/growth of Pt nanoparticles under the synthesis using formic acid or formaldehyde as reducing agents. CO has been found ...to affect not only the dynamics of the Pt(IV) to
Pt
x
0
transformation but also the size of the formed particles (1.1–3.9 nm) deposited on the carbon support (ca. 20 wt% Pt). The dual role of CO due to combining the functions of a stabilizer and a reducing agent has been shown. The study demonstrates that the introduction of the dispersed carbon support to the reaction medium leads to the enhancement of the CO positive effect on the microstructure of Pt/C catalysts. In this case, the spatial distribution of Pt nanoparticles over the carbon support surface becomes more uniform that is conducive to increasing the electrochemical surface area. Thus, CO is a unique reagent used to control the microstructure of Pt nanoparticles during their wet synthesis.
The need to reduce platinum content in PEMFC catalyst layers has sparked a new wave of interest in ways to control the microstructure of Pt/C catalysts, which must combine high platinum surface area ...and activity. A comparative study of platinum nanoparticle nucleation/growth under a liquid-phase synthesis of Pt/C materials, with formaldehyde and formic acid being used as reducing agents, has been carried out. Analysis of the color change in the reaction medium and the in situ spectral-kinetic studies performed with absorption spectroscopy, were used as methods to study the reactions kinetics. The effect of the synthesis temperature on the features of the Pt(IV) reduction stages, nucleation/growth of Pt(0) nanoparticles, as well as on the size of the resulting Pt nanoparticles were studied. The role of the ethylene glycol and its derivatives, formed in the reaction medium at high pH, in the processes of Pt(IV) reduction and in the Pt(0) nanoparticles formation, is shown. The positive effect of the dispersed carbon support on the morphological characteristics of the resulting Pt/C catalysts is demonstrated, with carbon being introduced into the reaction medium in the initial stage of the synthesis. The roles of homogeneous and heterogeneous phase formation in the synthesis of Pt nanoparticles and Pt/C materials in the liquid phase are estimated.
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•Pt NPs nucleation/growth under a liquid-phase synthesis with formaldehyde and formic acid has been studied.•Analysis of the color change and the in-situ UV–vis studies were used to study the reactions kinetics.•The effect of temperature on the Pt NPs size and Pt/C morphology has been considered too.•The ethylene glycol plays a significant role in the Pt(IV) → Ptx(0) transformation.•C-powder being introduced into the reaction medium in the initial stage of the Pt NPs formation improve Pt/C morphology.
The article presents an analytical review of the methods for determining the activity of water in food products. This is necessary in order to select among several methods the most suitable, which ...can be taken as a basis for further development of the methodology for determining water activity for non-smoking tobacco and nicotine-containing products.Water activity is an indirect indicator of microbiological contamination and is particularly important for tobacco and non-tobacco products consumed directly without burning. When water activity values are relatively high in Non-tobacco nicotine-containing products of oral type (NTNCPOT), microflora can develop. Non-tobacco nicotine-containing oral consumption products are actively marketed and are partially replacing traditional nicotine “consumption” methods. A distinctive feature of this product is its method of consumption, which is that as a result of consumption there is no process of inhaling tobacco smoke, which has a negative impact on the human body. On this basis, this product is a less dangerous alternative to smoking cigarettes. Since the products are so widespread, it is necessary to establish quality control. Water activity is not a standard indicator for controlling tobacco products, but since these products are intended for oral consumption, this indicator should begin to be defined as one of the most important for consumer safety. For non-smoking tobacco and nicotine-containing oral products, the CORESTA CRM88 method is the most appropriate. In order to develop a methodology for determining water activity and establishing the necessary values, further study of smokeless tobacco products and non-smokeless nicotine-containing oral products is needed.
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