Scientific Research Institute of Metallurgical Technology (Russia)

ABSTRACTHalitosis is a condition associated with bad breath. Although halitosis is a disease in its own right, it is often a symptom of more serious diseases (diabetes mellitus, renal failure, azotemia, etc.). The currently used method for diagnosing halitosis is the organoleptic method, which relies on a trained specialist evaluating the patient's breath odor. This approach to diagnosing halitosis is subjective, uncomfortable for both patient and doctor, and necessitates the involvement of a specially trained professional. As an alternative, instrumental diagnostics employing metal oxide semiconductor (MOS) sensor arrays offer a promising avenue by enabling patient classification through predeveloped models. This paper considers the application of seven MOS sensors of different compositions at three different temperatures. Different methods of chemometric data analysis were applied: k‐nearest neighbors (kNN), decision trees (DT), support vector machine (SVM), logistic regression (LR), and projection on latent structures discrimination analysis (PLSDA). All applied methods demonstrated their effectiveness and achieved selectivity, sensitivity, and accuracy values exceeding 85%. Additionally, a combined classifier leveraging responses from all previously studied classifiers was explored, achieving near‐perfect classification accuracy.

Nowadays, the principle of balanced development of the machine building industry and, at the same time, the preservation of the natural environment is fundamental in the modern world. The processes used in the technological cycles of machine building enterprises should be safe both for humans and for the natural environment. One of the types of chemical and thermal treatment of metal is the process of liquid carbonitration, which allows improving the exploitation properties of treated pieces. As a result of this technology, two types of waste are generated. For a toxicological evaluation of the waste of carbonitration process, two test cultures were chosen as model organisms: Daphnia magna and Scenedesmus quadrcauda. In the course of the study, it was found that wastes from the process of carbonitration in certain concentrations have an acute toxic effect and belong to the 3rd and 4th hazard classes.

For many years an important task for metallurgical scientists is the search for alternative technologies of iron production from mineral raw materials without using expensive coke, natural gas and with the least pressure on ecology. Technologies are required with maximum extraction of iron from ore, and with the least pollution of the atmosphere using cheap and least scarce reducing agents, for example power generating coal. Recently in OAO VNIIMT a new method has been developed and proven under laboratory conditions for direct preparation of iron by reduction of fine-grained material with solid reducing agent in a direct current electric arc furnace, including ground ore, iron-bearing sludge, etc. This technology makes it possible to prepare cast iron containing 3–4% carbon in a molten condition that may be granulated, cast into pigs, and treated in a ladle-furnace unit with minimum specific yield of gas and slag.

Thermal strengthening of complex profiles by cooling in water jets is replacing the traditional technology: quenching in oil. This technology has been tested in laboratory conditions and introduced experimentally. It permits the attainment of optimal self-tempering temperature by regulating the cooling time. That permits the creation of metal structures with good mechanical properties and excellent performance.

A shop has been organized at the Nizhniy Tagil Metallurgical Combine to make slag-forming mixtures and a factory standard has been developed for its products. The quality of the mixtures is fully consistent with the requirements established for mixtures used in the continuous casting of steel. The mixtures reliably insulate the meniscus of the metal in the mold and provide the necessary degree of lubrication between the skin of the solidifying ingot and the walls of the mold. The technology used to prepare the mixtures makes it possible to change over from one type of slag-forming mixture to another without stopping production.