Iron polymorphism, as a basic phase transformation in the industrial technology of iron-carbon alloys, manifests itself in three forms in iron heating and cooling. An analysis of the literature data revealed a lack of information about the mechanism of pure iron polymorphic transformation. In this work, an experimental verification of the second polymorphic transformation α-Fe ↔ γ-Fe is carried out using high-resolution differential scanning calorimetry (DSC). The object of the study are samples made from wire of technically pure iron (TPI–99.88

Background: Microsporum canis (Bodin, 1902) is a dermatophyte, which is widely represented in the developing and the developed world alike. Commonly transmitted from domestic animals it is particularly dangerous for immunosuppressed patients due to AIDS, cancer or transplant surgery. Search for new perspective antimycotic derivatives becomes an urgent task in the disease containment. Previously, several quinolinium analogs were screened for their antibacterial activity (E. coli, St. aurous) by our research team. Furthermore, some N-phenylbenzoquinaldinium derivatives have shown antifungal activity against Candida albicans and Candida krusei. Aims: In this study, we sought to investigate fungicidal properties of N-arylbenzoquinaldinium derivatives against a clinical strain of Microsporum canis for future medicinal applications. Materials and Methods: N-phenyl-[f]-benzoquinaldinium salts were prepared by a variation of the previously described technique and tested against a clinical strain of the fungus of Microsporum canis 114 harvested from pathogenic material of a patient (Perm, Russia, 2014). Results: N-phenyl-[f]-benzoquinaldinium tetrafluoroborate has shown antifungal activity par to (or exceeding) that of commercially available medication. Moreover, this benzoquinaldinium analog can be potentially labelled with tritium by our nuclear-chemical method, making it amenable for the sensitive pharmacokinetic studies. Conclusions: N-phenyl-[f]-benzoquinaldinium tetrafluoroborate has been shown as a promising compound for the further development of potent antifungal agents as well as radiotracers for further elucidation of biological pathways of antifungal activity.

Differential scanning calorimetry was used to study the regularities of polymorphic α↔β-transformation in polycrystalline cobalt. The value of the activation energy of the α->β-transformation during heating of cobalt (290-50 kJ/mol), enthalpy and entropy, depending on the thermal history of the metal, is determined. It is shown that the mechanisms of recrystallization under heating are closer to the first-order I phase transformations. When cooling under conditions of limited diffusion mobility of cobalt atoms, recrystallization is apparently carried out due to the passage of several diffusion-free mechanisms of phase transformation, implemented in close temperature ranges. Keywords: activation energy, cobalt, calorimetry, polymorphism, enthalpy, entropy.

The regularities of the α ↔ β polymorphic transformation in VT 1-00 polycrystalline titanium are investigated using differential scanning calorimetry. The activation energies of the α → β transformation upon titanium heating (760 ± 30 and 1100 ± 100 kJ/mol) are determined and are found to be dependent on the thermal previous history of the metal. It is proposed that the transformation mechanisms during heating and cooling are controlled by nondiffusive and diffusive mechanisms realized in overlapping temperature intervals.

Differential scanning calorimetry was used to study the Co-C nanocomposite, which is an array of ultrathin carbon nanocages encapsulated cobalt nanoparticles. The activation energy of the α-β transformation of the nanocomposite and the value of its endothermic effect have been estimated. Thermal effect is much greater than those values ​​that correspond to the observation conditions for α-β transformations in massive cobalt samples. The idea was put forward that transitional transformation is assumed by a non-diffusion, massive mechanism.

Differential scanning calorimetry was used to study the Co-C nanocomposite, which is an array of ultrathin carbon nanocages encapsulated cobalt nanoparticles. The activation energy of the α-> β transformation of the nanocomposite and the value of its endothermic effect have been estimated. Thermal effect is much greater than those values that correspond to the observation conditions for α->β transformations in massive cobalt samples. The idea was put forward that transitional transformation is assumed by a non-diffusion, massive mechanism. Keywords: phase transitions, carbon nanocages, cobalt, activation energy.

Differential scanning calorimetry was used to study the regularities of polymorphic αβ transformation in polycrystalline cobalt. The value of the activation energy of the αβ transformation during heating of cobalt (29050 kJ/mol), enthalpy and entropy, depending on the thermal history of the metal, is determined. It is shown that the mechanisms of recrystallization under heating are closer to the first-order I phase transformations. When cooling under conditions of limited diffusion mobility of cobalt atoms, recrystallization is apparently carried out due to the passage of several diffusion-free mechanisms of phase transformation, implemented in close temperature ranges.

Based on the analysis of differential scanning calorimetry data, the possibility of classifying the observed endothermic or exothermic transformations as phase transformations of the first oder is considered. Two approaches have been implemented. The first is based on the correspondence between the temperatures of the maximum conversion rate and the temperatures of the extrema on the second derivative of the differential scanning calorimetry signal with respect to temperature. In the second approach, the phase transformation is considered as a kind of kinetic reaction of a chemical process with the determination of some parameters included in the kinetic equations. In this case, the order parameter of such reaction n is obtained from the analysis of the differential scanning calorimetry signal shape in the region of phase transformation registration temperatures. Using the example of experiments carried out during thermal cycling of titanium iodide samples, it is shown that both the first and second approaches make it possible to fairly adequately attribute the processes that cause calorimetric effects on the dependences of differential scanning calorimetry to first-order phase transitions. In particular, the obtained results of differential scanning calorimetry during heating and cooling of iodide titanium show that polymorphic transformations in it are realized by various mechanisms depending on the rate of thermal cycling and the thermal history of the metal.

Using differential scanning calorimetry, the regularities of polymorphic α↔β transformation in polycrystalline titanium WТ 1-00 were studied. The values of the activation energy of the α↔β transformation during heating of titanium (760±30 kJ/mol and 1100±100 kJ/mol) were determined, which were dependent on the thermal history of the metal. It is suggested that the recrystallization mechanisms during heating and cooling are controlled by diffusion-free and diffusion mechanisms implemented in overlapping temperature intervals.

С использрванием сканирующей дифференциальной калориметрии проведено исследование фазовых превращений в стали 38Х2МЮА и азотированном слое, полученном ионным азотировании. При нагреве стали в межкритическом интервале температур (между точками Ас1 и Ас3) можно выделить два эндотермических участка, Рh1 и Рh2. Первый из них относится к переходу перлита в аустенит. Второй – отвечает некоторому новому эффекту. В углеродистых сталях с близким содержанием углерода этот эндотермический эффект отсутствует. При охлаждении этой стали после аустенизации между точками Ar3 и Ar1 не фиксируются особенности, характерные для сталей с тем же содержанием углерода. При нагреве азотированного слоя обнаружено в нем пртекание фазовых переходов, обусловленных присутствием высокоазотистых фаз e и g’. В межкритическом интервале температур не наблюдается эффекты, характерные для этой стали в отсутствии азота. Однако при охлаждении в межкритическом интервале температур регистрируется заметный экзотермический эффект, отсутствующий в этой стали без азота. Показано, что даже после диссоциации фаз e и g’ и частичной эвакуации азота, при последующем термоциклтровании последствия введения азота сохраняются во всем межкритическом интервале температур.

Методами дифференциальной сканирующей калориметрии и термогравитационного анализа исследована термическая декомпозиция гидрида титана. Впервые экспериментально показано, что деструкция гидрида титана совершается в три этапа. Высказано предположение, что это связано с дискретным переходом от одной модификации гидрида титана с высокой концентрацией атомов водорода к другим, с более низким их содержанием

Differential scanning calorimetry belongs to a group of rather unique study methods, which makes it possible to investigate in situ the regularities of structural and phase transitions in metallic alloys within a broad range of temperatures (from –100 to 1600°C) at a sufficiently high precision of registering the heat effects of phase transitions. Our paper reviews the results of DSC studies for the alloys based on metals with polymorphism, the thermoelastic martensitic transitions, the decomposition and formation of solid solutions, and the crystallization of amorphous metallic metal-metal alloys. This review puts particular emphasis on considering phase transitions in hydrogen-containing alloys, both crystalline and amorphous.

Abstract Quinazoline derivatives are well known to have a diverse array of therapeutic activities. Unfortunately, “classic” chemical synthesis does not provide an opportunity for the formation of N-phenyl quaternary 1,3-diazinium compounds. A devised nuclear-chemical method of synthesis based on chemical effects of nuclear transformations enables a new way of the direct nitrogen atom phenylation by the nucleogenic (generated by tritium β-decay) phenyl cations in 1,3-diazines, furnishing, based on our prediction, formation of previously unknown derivatives with N-phenyl quaternary quinazolinium scaffold.

A study of ion-molecular reactions of fluoro-substituted phenyl cations with benzopyridine derivatives demonstrated the following: (a) at present only the nuclear-chemical method enables the reaction of a direct phenylation of the nitrogen atom in benzopyridine derivatives, which makes it possible to obtain previously unknown quaternized structures, and (b) generation of nucleogenic phenyl cations with various substituents leads to a simultaneous introduction of the required substituents into the aromatic ring at the nitrogen heteroatom. Quantum-chemical calculations additionally confirmed the assumption about the pathways of the ion-molecular reactions with nucleogenic phenyl cations.

Features of the polymorphic transformations in iron of different purity and zirconium iodide were studied using high-resolution calorimetry methods. It has been suggested that the polymorphic transformations in zirconium, in contrast to the polymorphic transformations in iron, were controlled by two mechanisms: diffusion-free and diffusion. The relationship between them depends on the rate of thermal cycling and the thermal background of zirconium.

Data on the calorimetric effects during the structural phase transformations in iron–carbon alloys (steels) are presented. No relationships are revealed between temperature points A 3 ( A m ) and the calorimetric effect temperatures during steel thermal cycling. The conclusions in favor of the mechanisms of the phase transformations resulting in the observation of these calorimetric effects are presented. The obtained results can be used to study the conditions of heat treatment with quenching of steels from the intercritical temperature range.

The results of the calorimetric studies of thermal dissociation of titanium, zirconium, magnesium, and palladium hydrides performed in recent years are presented. The multiplet character of thermal dissociation characteristic of all these hydrides is shown. A good correlation between the course of differential scanning calorimetry curves and the results of thermogravimetry has been demonstrated. The discrete nature of the decomposition processes is established. A sequence of mechanisms occurring during the heating of transition metal dihydrides in a medium with a low partial pressure of hydrogen has been proposed: rearrangement in the hydride phase; destruction of metal hydrogen bonds to form a solid solution supersaturated with hydrogen; diffusion of hydrogen to the interface of solid phase environment; molization of hydrogen at the exit from the solid phase. (C) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

Polymorphic transformations in iron of differing purity and zirconium iodide have been studied by the high-resolution calorimetry method. The hypothesis has been made that polymorphic transformations in zirconium, unlike those in iron, are governed by two mechanisms-diffusionless and diffusion. Which of them prevails depends on the temperature cycling rate and thermal history of the zirconium.