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Abstract—The acoustic emission signals that arise during the interaction of metal zirconium samples with hydrogen, as well as the changes that occur in hydrogenated samples and are sources of high-amplitude acoustic signals, are studied. Hydrogenation of pieces of compact zirconium iodide ranging in size from 5 to 10 mm, shavings obtained from compact zirconium iodide with a linear particle size from 2 to 3 mm and a thickness of ≈0.2 mm, “coarse” electrolytic zirconium powder with a fraction from 80 to 550 μm, and “fine” electrolytic zirconium powder with a particle size of less than 80 μm is carried out. It is established that the source of high-amplitude acoustic signals in all cases is the cracking of zirconium particles at the macro level, which leads to the formation of extended cracks and fractures on the surface of individual particles, as well as to the grinding of the initial materials. Cracking and grinding are caused by deformation and internal stresses that arise in the samples owing to an increase in the volume of the solid phase during hydrogenation. It is shown for the first time that the atomic ratio [H]/[Zr] in the solid phase corresponding to the maximum amplitude of the acoustic emission signal naturally increases in the series pieces of compact zirconium iodide–shavings of zirconium iodide–"coarse" electrolytic zirconium powder–"fine" electrolytic zirconium powder, which is in good agreement with the results of earlier similar studies carried out on the hydrogenation of titanium metal samples.

•Using carbon black from waste tires for catalyst production has positive result.•Metals/carbon black catalysts decrease the energy of activation by 13 %.•Tri-metallic catalysts provide the best decomposition interval narrowing.

Abstract: The surface properties of powder particles of 316L steel and Inconel 718 alloy applied in additive technologies have been studied, including interaction with hydrogen of specimens fabricated from these powders by selective laser melting.

Information about the surrounding atmosphere at a real timescale significantly relies on available gas sensors to be efficiently combined into multisensor arrays as electronic olfaction units. However, the array’s performance is challenged by the ability to provide orthogonal responses from the employed sensors at a reasonable cost. This issue becomes more demanded when the arrays are designed under an on-chip paradigm to meet a number of emerging calls either in the internet-of-things industry or in situ noninvasive diagnostics of human breath, to name a few, for small-sized low-powered detectors. The recent advances in additive manufacturing provide a solid top-down background to develop such chip-based gas-analytical systems under low-cost technology protocols. Here, we employ hydrolytically active heteroligand complexes of metals as ink components for microplotter patterning a multioxide combinatorial library of chemiresistive type at a single chip equipped with multiple electrodes. To primarily test the performance of such a multisensor array, various semiconducting oxides of the p-and n-conductance origins based on pristine and mixed nanocrystalline MnOx, TiO2, ZrO2, CeO2, ZnO, Cr2O3, Co3O4, and SnO2thin films, of up to 70 nm thick, have been printed over hundred μm areas and their micronanostructure and fabrication conditions are thoroughly assessed. The developed multioxide library is shown to deliver at a range of operating temperatures, up to 400 °C, highly sensitive and highly selective vector signals to different, but chemically akin, alcohol vapors (methanol, ethanol, isopropanol, and n-butanol) as examples at low ppm concentrations when mixed with air. The suggested approach provides us a promising way to achieve cost-effective and well-performed electronic olfaction devices matured from the diverse chemiresistive responses of the printed nanocrystalline oxides.

This review addresses various approaches to television projection imaging on large screens using lasers. Results are presented of theoretical and experimental studies of an acousto-optic projection system operating on the principle of projecting an image of an entire amplitude-modulated television line in a single laser pulse. We consider characteristic features of image formation in such a system and the requirements for its individual components. Particular attention is paid to nonlinear distortions of the image signal, which show up most severely at low modulation signal frequencies. We discuss the feasibility of improving the process efficiency and image quality using acousto-optic modulators and pulsed lasers. Real-time projectors with pulsed line imaging can be used for controlling high-intensity laser radiation.

The present study centres on room‐temperature ionic liquids (ILs) as entrainers in extractive distillation of chloromethane/isobutane mixtures. The binary system, chloromethane/isobutene, is an azeotropic system. In this study, IL entrainers are shown to be able to break the azeotrope and, thus, assure the separation in the whole range of chloromethane/isobutane ratios. ILs formed from different cations and anions are considered and their influence on chloromethane/isobutane separation is explored. Among the ILs studied, those containing the trifluoromethanesulfonate ([CF3SO3]–) or tricyanomethanide ([C(CN)3]–) anion are demonstrated to exhibit an enhanced potential for chloromethane/isobutane separation compared to the corresponding ILs based on the bis(trifluoromethylsulfonyl)imide ([Tf2N]–) anion. Moreover, the ILs enclosing these anions are cheaper than those with the [Tf2N]–anion. Thus, the separation ability, solubility of chloromethane/isobutane mixtures, and costs of IL entrainers can be adjusted by the right choice of cations and anions.

This paper presents an extensive study on the feasibility of ionic liquids (IL) for the extractive distillation of propene‐propane mixtures. A new experimental method for express screening of non‐volatile entrainers was elaborated. A series of ILs and their mixtures were screened at ambient temperature and low pressures. The screening results show that every tested IL turns a low boiler propene into a high boiler and the alkene‐to‐alkane separation factor can be as low as 0.28. The solubility and separation efficiency can be tuned by adjusting the chemical structures of the ions forming the IL. It was found that shortening of the alkyl substituents of the imidazolium ions leads to a decrease in capacity and to an increase in the separation factor. Interestingly, ILs containing nitrile functionalities in either the cation or the anion showed, in our experiments, enhanced separation ability combined with still good capacities. From our thermodynamic measurements, [EMIM][[B(CN)4] was proved to be the most promising candidate. Binary mixtures of ILs were also tested and resulted in separation factors and capacities between the values for the individual ILs. For the most promising candidates, also autoclave measurements at elevated temperatures and pressures were carried out. These experiments indicate that the separation ability decreases with growing temperature and loading. In general, our study definitely proves the high potential of ILs to act as entrainers in the extractive distillation of propene‐propane mixtures or for the separation of any other low‐boiling alkene‐alkane mixture.

Abstract: A combination of N-hydroxysuccinimide and p-toluenesulfonic acid is proposed as an efficient catalyst for the preparation of a great variety of imidazo[1,2-a]pyridine derivatives by three-component condensation of aromatic isocyanides, aldehydes, and 2-aminopyridine. The advantages of this procedure are high yields of the target products and the absence of side reactions.

Abstract: The reactions of β-naphthol with 5-diazoimidazoles and imidazolyl-5-diazonium salts containing chemically different carboxamide groups in position 4 were studied. Heterocyclization of 4-arylcarbamoyl-5-(2-hydroxynaphthylazo)imidazoles formed in these reactions was investigated. The presence of the NH fragment in the amide group prevents this process, the reaction giving instead 3-substituted 3,7-dihydroimidazo[4,5-d][1,2,3]triazin-4-ones, which is due to reversibility of C-azo coupling. Methods for modification of 1-ethoxycarbonyl group in the naphtho[2,1-e]imidazo[5,1-c][1,2,4]triazine system were developed and used to prepare substituted carboxamides inaccessible by other routes.

The density and porosity of synthetic opals with spheres 315 and 1000 nm in diameter were measured in relation to the annealing temperature. At annealing temperatures of up to 500°C, the seeming density and porosity remain almost unchanged. Then, at temperatures of up to 950°C, the density increases gradually and, accordingly, the porosity decreases due to the collapse of nanopores caused by the sphere substructure. As the annealing temperature increases further, the opal density increases sharply up to 2.22 g/cm3(which corresponds to the density of amorphous silica) and the open microporosity due to the voids between spheres disappears. Differential thermal and thermogravimetric analyses showed that SiO2powders with particles with average size of 315 and 1000 nm can have, respectively, two-and three-level systems of micro-and nanopores.

Abstract Preincubation of cultured slices of the olfactory cortex of rat brain with heat shock protein in a concentration of 1 µg/ml protected the pre- and postsynaptic mechanisms of glutamatergic synaptic transmission from glutamate excitotoxicity (50 mM) inducing blockade of excitatory postsynaptic function and reducing presynaptic processes. It was hypothesized that heat shock protein protects AMPA and NMDA receptor-mediated processes.

A modified version of the optical scheme for second harmonic generation in a copper vapour laser is proposed, in which mirror focusing optics mounted at an angle of 45° to the incident light beam is used instead of lens focusing optics. A mean radiation power 1.4 W at a wavelength of 255.3 nm is achieved with a conversion efficiency of 28%. A high-speed system for controlling the spectral and temporal parameters of the UV radiation is developed and studied for the first time. The use of such a system in technological setups will considerably extend the range of their application.

Abstract The comparative reactivity of heterocyclic diazo compounds and the corresponding diazonium salts in C-azo coupling reactions was studied using imidazole, pyrazole, and triazole derivatives as examples.The reactivities of pyrazole- and imidazole-derived diazonium salts are much lower than those of thiadiazole- and 1,2,4-triazole-derived diazonium salts but higher than those of pyrrole and indole diazo compounds.

Successive alkylation of 5-(3-phenylthioureido)-3H-imidazole-4-carboxamides with alkyl halides and chloroacetone gave (N-oxopropylimidazolyl)isothioureas, which were easily converted into derivatives of purine and imidazopyrazinone. In the case of ethyl 5-(3-phenylthioureido)-3H-imidazole-4-carboxylate, primary alkylation occurs at the N atom of the imidazole ring. Reactions of 5-(3-phenylthioureido)-3H-imidazole-4-carboxamides with haloketones afforded a number of 4-hydroxy-2-imidazolyliminothiazolidines and 2-imidazolylimino-Δ4-thiazolines.

A new convenient method for the synthesis of 1,4-benzothiazepin-5-ones by a one-pot procedure including condensation of thiosalicylic acid with chloroacetone and the reaction of the resulting 2-(acetoxythio)benzoic acid without isolation with primary amines and isocyanides is proposed. This method can be used for the combinatorial search of compounds with biological activities in the 1,4-benzothiazepine series.

Application of corticotropin-releasing factor (CRF) at concentrations of 10–9and 10–8M to living brain slices induced activation of the pre- and postsynaptic excitatory components of focal potentials recorded in the slices. The amplitudes and durations of the AMPA and NMDA components of EPSP increased during exposure to CRF, while the amplitude of the GABAB-mediated IPSP was suppressed. At the higher CRF concentration (10–8M), cells in slices showed epileptiform discharges. The effects of CRF were reversible and disappeared on washing. Long-term treatment with CRF (90 min) induced changes in cells in slices similar to those associated with long-term post-tetanic potentiation. These data provide evidence that CRF has marked activatory properties and influences the glutamatergic and GABAergic systems.

The protective effects of corticoliberin on living rat olfactory cortex slices during perfusion with “dysfunctins” extracted from cerebrospinal fluid of drug addicts were studied. Isolated perfusion of slices with medium containing “dysfunctins” led to irreversible suppression of the amplitude of individual components of focal potentials induced by electrical stimulation of the lateral olfactory tract. The maximum level of depression was seen for the AMPA and NMDA components of EPSP. Preliminary perfusion of slices with medium containing corticoliberin (100 nM) for 15 min partially, and for 30 min completely protected processes mediated by activation of AMPA and NMDA receptor mechanisms from the negative influences of “dysfunctins.” It is suggested that corticoliberin can induce its protective effects either via its own specific receptors or non-specifically via glutamate receptors. It is also possible that both of these mechanisms act in combination.

Living slices of Wistar-Kyoto rat brain olfactory cortex were used to study the effects of the thiol-oxidizing agent 5,5'-dithiobis(2-nitrobenzoic acid) (DTNB), which inhibits NMDA receptor activity, on changes in the generation of evoked focal potentials (NMDA and non-NMDA EPSP) in response to long-term and short-term anoxia, which induces functional damage and facilitates increases in the resistance of neurons to severe hypoxia respectively. These studies showed that DTNB (200 'M) efficiently prevented the suppression of focal EPSP generation due to long-term anoxia in most slices. In addition, DTNB partially reversed the protective effect of preconditioning with short-term anoxia on the impairment of focal EPSP generation induced by long-term anoxia. This affected the NMDA component of the EPSP to a greater extent than the non-NMDA component. The possible role of changes in the state of modulatory redox sites of NMDA receptors in the mechanisms of functional damage and increases in neuron resistance due to hypoxia is discussed.

Diazotization of 4-R-5-aminoimidazoles (R = CONHAr, CONHAlk, morpholinocarbonyl, or piperidinocarbonyl) with sodium nitrite in aqueous solutions of mineral acids afforded the corresponding 5-diazoimidazoles, whereas the reactions in concentrated tetrafluoroboric acid produced imidazolyl-5-diazonium salts. In the solid phase, diazonium salts are transformed into the corresponding diazo compounds.

Measurements of the angular correlation of annihilation radiation and infrared absorption spectra were conducted with porous silicon samples, containing capillary macropores with a diameter of about 1 μm. The set of data shows that a high proportion of Si–O bonds contribute to positron annihilation and IR absorption for porous silicon. Annihilation parameters and estimated values of the specific surface area point to the availability of a nanoporous system in the macroporous silicon. Most likely the macropore surface is covered by the nanoporous material to a thickness of 100–200 nm. The characteristic size of the nanopores is estimated at 1–2 nm. Si–O bonds are located at the nanopore surface and do not exceed one monolayer.

The reaction of ethyl 5-phenylthioureido-3H-imidazole-4-carboxylate with bromoacetic acid afforded (imidazolylimino)thiazolidinones, which were transformed into the corresponding 5-arylidene-4-thiazolidinones by the reactions with aldehydes. Under the conditions of the Knoevenagel reaction, the thiazolidine ring in derivatives of 4-(4-oxothiazolidin-2-ylideneamino)-3H-imidazole-4-carboxamides was opened to form substituted guanidines.

A preventive short-term hypoxia (preconditioning) increases neuronal resistance against subsequent strong hypoxic effects. Literature review and authors' own data on molecular-cellular mechanisms of the hypoxic preconditioning, are presented. Participation of intracellular signal transduction, genome, stress-proteins, and neuromodulating peptides in this process, is discussed. The role of glutamatergic as well as calcium and phosphoinositide regulatory systems and neuromodulating factors as the components of a “volume” signal transmission are analyzed in hypoxic precondition-associated induction of functional tolerance mechanisms against acute harmful effects in neurones of olfactory slices.

The nitro group at position 5 in 4,5-dinitroimidazole was substituted by reaction with ethylenediamine with the formation of 5-(2-aminoethylamino)-4-nitro-1H-imidazole. The acylation of the compound was studied; a new bicyclic derivative of imidazole containing a benzothiazole fragment was obtained.

Stability is discussed for methods of calibrating an optical-absorption gas analyzer on the basis of functions having completely monotone derivatives.

Using the model of long-term posttetanic potentiation (LTP) in slices of the olfactory cortex of rat brain, we have tested a hypothesis according to which activation of nerve cells results in a release of neuromodulatory factors into extracellular space; these factors, diffusing over significant distances, are capable of synchronously modifying the initial reactivity of neuronal populations. Using the technique of bioassay, i.e., transfer of perfusate from the tetanized donor slice to the recipient slice, in combination with pharmacological and neurochemical techniques, we found that in response to excitation, the cells of olfactory cortex slices secrete peptides. This observation confirms the above hypothesis. The spectrum of released peptides changes depending on the degree of cell excitation and, in addition, is frequency-dependent. It has been demonstrated that the key target of these peptides are N-methyl-D-aspartate glutamate receptors. We propose that two peptide pools are involved in the initial and late phases of LTP. The possible significance of peptide cell regulation in mechanisms of neuronal plasticity is discussed.

This review presents published data and results from our own studies providing evidence for the important role of volume, non-synaptic transmission of adaptogenic signals in the mechanisms forming the long-term adaptive reactions of the brain. The importance of chemical factors involved in volume transmission and secreted by cells in this process is discussed. Special attention is paid to peptides—possible mediators of volume transmission of adaptive-type signals. Evidence has been obtained for the presence of peptides and their role in the mechanism of development of adaptive brain reactions of different origins, especially those arising in response to tetanic stimulation of neurons and transient hypoxic stress. An original method for testing for the effects of neuromodulator factors released by cells in donor slices subjected to these treatments on recipient slices was used to show that these factors had pronounced effects on synaptic transmission and could induce long-term potentiation of synaptic transmission, protecting against functional derangements due to prolonged anoxia. Blockade of protein synthesis in donor slices subjected to adaptogenic treatments suppressed the appearance of these effects. The review concludes with a discussion of the mechanisms of interaction of the synaptic and volume transmission of signals involved in forming long-term adaptive brain reactions.

Based on a spectrokinetic study (simultaneous measurements of the concentrations of surface complexes and reaction rate usingin situIR spectroscopy), a hypothesis is proposed which explains synergism in the reaction of NO reduction by propane on a mechanical mixture of commercial oxide catalysts.

Cyclization of azo compounds, synthesized from 5-diazoimidazoles and 2-naphthol or p-substituted phenols, into naphth[2,1-e]imidazo[5,1-c]-1,2,4-triazines and benz[e]imidazo[5,1-c]-1,2,4-triazines occurs only in the presence of p-toluenesulfonic acid. Imidazo[4,5-d]-1,2,3-triazines are also formed in this reaction when an amide substituent is present in the imidazole ring.

In the reaction of NO reduction by propane in excess oxygen, the activity of a binary mixture of commercial oxide catalysts is higher than should be expected if it were proportional to the activities of separate catalyst components. This synergism reveals itself in the fact that the conversion of NO and C3H8is higher when the catalyst is a mechanical mixture than the sum of conversions over separate catalysts, all other conditions being the same. Based on the kinetic and thermal desorption measurements, the experimental conditions are found under which the synergism is observed. A hypothetical mechanism is proposed.

A series of N-alkyl- and N-aryl-2-cyano-2-diazoacetamides was synthesized by the reaction of 2-amino-2-cyanoacetamides with sodium nitrite in hydrochloric acid. The mechanism of their heteroclectrocyclization to 5-hydroxy-1,2,3-triazoles was investigated kinetically and theoretically by the B3LYP/6-31+G*method. The conclusion was made on the basis of the determined activation energy of the cyclization process. reaction parameters ϖ, and kinetic isotope effects, that there is a difference between the mechanisms of cyclization of the N-alkyl and N-aryl derivatives of 2-cyano-2-diazoacetamide; cyclization of the N-alkyl derivatives takes place by a monorotatory mechanism, while cyclization of the N-aryl derivatives takes place by a mechanism where one of the stages is heteroelectrocyclization of 2-diazoacetimidates.

2-(2-Carbethoxy-1-amino-1-thio)ethylenepyradinium(isoqunolinium) ylids were obtained by the reaction of carbethoxycyanomethylpyridinium(isoquinolinium) ylids with hydrogen sulfide. In an alkaline medium they cyclize into 5-mercaptosubstituted imidazo[1,2-a]pyridines(isoquinolines). The structure of the latter compounds was confirmed by PMR and IR spectroscopy.

The acylation of 5(4)-aminoimidazole derivatives was studied. It is shown that acylation by means of carboxylic acid anhydrides and chlorides takes place at the amino group, whereas acylation by means of chlorocarbonic acid esters takes place at the nitrogen atoms of the imidazole ring. Methods for the selective introduction of a carbomethoxy group in the 1, 3, and 5 positions of the 5(4)-aminoimidazole-4(5)-carboxamide molecule were developed.

Carbonyl-substituted derivatives of diazoacetonitrile have been obtained by the diazotization of amines and by diazo-group transfer which, under the action of hydrogen halide, have been converted into 4-carbonyl-substituted 5-halo-1H-1,2, 3-triazoles. The structures of these compounds have been confirmed by mass spectrometry and independent synthesis.

The synthetic methods for 1,3,4-thiadiazines and their intramolecular rearrangement reactions are reviewed.

The reaction of 5-amino-1,2,3-thiadiazol-4-carbothioamides with methyl iodide basically generates a-diazo-S-methylthioimidates and -carbothioimidolates. It is shown that the reactivity of the latter increases when either alkyl or aryl substituents are introduced at the nitrogen atom of the carbothioamide group

The reaction of derivatives of 5-hydroxy-1,2,3-triazole-4-carboxamide with phenyl isocyanate and phenyl isothiocyanate proceeds at the 4-carboxamide fragment of the first, leading to the formation of derivatives of N-phenyl-N'-(2-diazo-2-carbamoylacetyl)urea and -thiourea correspondingly.

Methods of synthesis and the physical, chemical, and biological properties of 1,2,3-thiadiazoles are systematized.

1,2,3-Triazol-5-olates are formed in the reaction of diazomalonodiamide and 2-diazo-2-cyanoacetic acid amide and N-methylamide with sodium ethoxide, triethylamine, and ammonia. The products of the reaction of 2-diazo-2-cyanoacetamide with primary amines are mixtures of 4-cyano-1,2,3-triazol-5-olates and 5-amino-1-alkyl-1,2,3-triazole-4-carboxamides.

The reactions of 4-chloroimidazo[4,5-d]-1,2,3-triazine with a number of nucleophilic reagents have been studied. Either replacement of the chlorine atom in position 4 of the 1,2,3-triazine ring or opening of the triazine ring with the formation of products of the interaction of the intermediate 5-diazoimidazole-4-carbonitrile with these nucleophiles occurs, depending on the nucleophilicity of the reagent.

A method for the synthesis of derivatives of 5 (or 4)-hydrazinoimidazole-4 (or 5)-carboxylic acid by reducing the corresponding diazoimidazoles with stannous chloride has been developed, and a number of hydrazones and semicarbazides have been synthesized. It has been shown that under the reduction conditions selected imidazo[4,5-d]-1, 2, 3-triazinone does not have cryptodiazonium properties.

The IR, UV, and PMR spectra of 5(4)-mercaptoimidazole-4(5)-carboxamide, 5(4)-hydroxyimldazole-4(5)-thiocarboxyamide, 5(4)-mercaptoimidazole-4(5)-thiocarboxamide, and the corresponding methyl derivatives were studied. It is shown that the mercaptoimidazoles obtained exist in the form of zwitterions in solution. The methylation of the mercapto- and hydroxyimidazoles with various methylating agents in solvents was investigated, and the reaction of the thioamides with hydrazine was carried out.