Analysis Of Reaction Products Research Articles

Low Temperature Methane Combustion Catalysts for Pellistors Investigated By Simultaneous Thermal Analysis

Introduction The early detection of explosive gas atmospheres is highly relevant for industrial process measurement technology and avoids the endangerment of people. In the field of safety technology, catalytic combustion sensors, so-called »pellistors«, are used to detect flammable gases such as hydrocarbons or hydrogen. Pellistor sensors measure the heat produced from catalytic oxidation of the gas by detecting the resistance alteration of a Pt-based heater induced by temperature changes using a Wheatstone bridge circuit. The heat generated is related to the kind and concentration of gas by specific combustion enthalpy [1]. The major advantages of catalytic sensors are simple operation principle, easy installation and calibration. However, state-of-the-art pellistors have some disadvantages, such as high operation temperatures of over 400°C, high-power consumption and high susceptibility to catalyst poisons. High-power consumption limits the usage of pellistors in mobile applications because of the short battery lifetime. Reducing operating temperature will contribute to decrease the power consumption.The primary gas recognition element of the pellistor is the catalytic layer. To reduce the operation temperature high active catalysts are required. Especially for detection of methane, which is one of the most inert combustible gases, catalysts of high activity or particularly high working temperatures of at least 450°C are mandatory. For this reason, a reliable detection of methane is the most important challenge. Catalysts implemented in nowadays pellistors were developed already in 1960s and contain Pd or/and Pt nanoparticles stabilized on a porous metal oxide support in its active chemical and physical state. Alumina and, to a lesser extent, zirconia are commonly used due to its high surface area and thermal stability [2]. However, some reports show that the application of metal oxides like CeO2 as support can lead to an improved sensor performance due to high oxygen storage and release ability [3]. The researches in the field of catalytic combustion provided many further evidences that especially metal oxides with spinel structures as Co3O4, NixCo3-xO4, Co3-xCuxO4, Co3-xZnxO4 etc., can contribute to catalytic combustion of methane and therefore considerably decrease the temperature for catalytic reaction [4]. New catalysts have the potential to considerably improve the performance of pellistors.This research focuses on the development of alternative, highly active catalysts based on spinels for catalytic detection of methane in the low-temperature range. Catalytic activity was investigated by Simultaneous Thermogravimetry-Differential Thermal Analysis (TG-DTA, termed as STA) coupled with Quadrupole Mass Spectrometer (STA-QMS). Method STA (NETZSCH, STA 409 CD-QMS 403/5 SKIMMER) is a calorimetric method to monitor the heat consumption (endothermic) or release (exothermic DTA signal) occurring by different processes. Heat release during exothermic oxidation reaction is measured by comparison the temperature of sample placed in an alumina crucible with that of reference crucible after calibration and signal normalization. In contrast to a pellistor, in which each element of the sensor including electronics, contacts and catalytic layer, etc. influences the formation of the sensing signal, STA shows unaffected thermal signal originating from catalytic reaction. Additionally, the complex preparation steps as in case of pellistor can be avoided. Thermal analysis like DSC [5] and DTA ensure comparable conditions for appropriate testing and investigation of different catalytic materials. QMS allows the analysis of gaseous residues and reaction products by ionization.For catalyst investigation, Co3O4 spinel doped with nickel (synth. NiCo2O4) and palladium (4wt% Pd/synth. Co3O4) were synthesized according to [4]. For comparison, commercial Co3O4 (comm. Co3O4) was used. Results and Conclusions Co3O4 spinel and his derivatives have been chosen for the investigation of catalytic activity. The thermal behavior of investigated oxides in synthetic air (reference) and in 1 vol% CH4 is shown in Fig. 1a. The mass spectrum presented for mass ion m/z of 44 for NiCo2O4 (Fig. 1b) confirms the CO2 evolution by CH4 injection into the chamber as a result of catalytic reaction. Figure 1: (a) DTA signal of four investigated catalysts at four temperatures (red line) measured successively in synthetic air (gray background) and 1vol% CH4 (green background); (b) simultaneously recorded mass spectrum (STA-QMS) of mass ion 44 from the NiCo2O4 sample. Spinel NiCo2O4 and 4wt% Pd/synth. Co3O4 (Fig. 1a) reveal first traces of activity already at 250°C, while undoped commercial Co3O4 shows a minor signal at 300°C first. Certainly, with temperature increasing the behavior changes. Consequently, NiCo2O4 is a preferred catalyst for low operation temperature. It shows higher activity at lower temperatures, whereas at higher temperatures (450°C) Pd doped Co3O4 catalysts prevail in catalytic activity.Especially doped NiCo2O4 spinel exhibited excellent catalytic activity towards methane oxidation. The structure-properties relation will be presented and discussed.

Prevalence and Antimicrobial Characteristics of Shiga Toxin-Producing Escherichia coli Isolates from Pork in Korea.

Shiga toxin-producing Escherichia coli (STEC) strains are important food-borne pathogens that can be transmitted through the consumption of food products derived from pigs. Moreover, antimicrobial resistance in STEC has been a matter of increasing concern. The aim of this study was to investigate the prevalence and antimicrobial characteristics of STEC isolates from pork in Korea. We isolated 131 isolates of E. coli from 334 pork samples collected from slaughterhouses and retail markets from 2008 to 2009. Among the 131 isolates, 6 (4.58%) were confirmed to belong to 6 different serotypes of STEC. All six STEC isolates contained stx1 and eaeA virulence genes, and four of them additionally carried the hly gene. The minimum inhibitory concentration (MIC) of 15 antibiotics (amoxicillin/clavulanic acid, ampicillin, cephalothin, cefoxitin, ceftiofur, gentamicin, neomycin, streptomycin, nalidixic acid, ciprofloxacin, colistin, chloramphenicol, florfenicol, tetracycline and sulfamethoxazole/trimethoprim) toward the STEC isolates was determined. As a result, three strains were associated with high MICs for florfenicol and chloramphenicol (64 μg/mL). Furthermore, all three strains were found to contain the florfenicol-resistant gene (floR) but not the chloramphenicol-resistant gene (cat). Sequence alignment and BLAST analysis of the polymerase chain reaction products of the floR gene indicated that they contained sequences with homology to the floR gene of E. coli or Salmonella enterica serovar, Heidelberg. This is the first report on the detection of floR in STEC isolated from pork obtained from retail markets in Korea.

Genomic recombination between infectious laryngotracheitis vaccine strains occurs under a broad range of infection conditions in vitro and in ovo.

Gallid alphaherpesvirus 1 causes infectious laryngotracheitis (ILT) in farmed poultry worldwide. Intertypic recombination between vaccine strains of this virus has generated novel and virulent isolates in field conditions. In this study, in vitro and in ovo systems were co-infected and superinfected under different conditions with two genomically distinct and commonly used ILTV vaccines. The progeny virus populations were examined for the frequency and pattern of recombination events using multi-locus high-resolution melting curve analysis of polymerase chain reaction products. A varied level of recombination (0 to 58.9%) was detected, depending on the infection system (in ovo or in vitro), viral load, the composition of the inoculum mixture, and the timing and order of infection. Full genome analysis of selected recombinants with different in vitro phenotypes identified alterations in coding and non-coding regions. The ability of ILTV vaccines to maintain their capacity to recombine under such varied conditions highlights the significance of recombination in the evolution of this virus and demonstrates the capacity of ILTV vaccines to play a role in the emergence of recombinant viruses.

Efficiency and mechanisms of antimony removal from wastewater using mixed cultures of iron-oxidizing bacteria and sulfate-reducing bacteria based on scrap iron

Treatment of antimony (Sb) mine drainage is generally regarded as a priority issue for regulatory authorities. In the study synergetic removal of Sb(V) from wastewater using cheap scrap iron inoculated with iron-oxidizing bacteria (IOB) and sulfate-reducing bacteria (SRB) was proposed. A strain of Enterobacter sp. (named as IOB-L), and Desulfovibrio sp. (named as GSRB) was first isolated separately, and Sb(V) removal performance in four different systems were investigated through batch experiment. It demonstrated that after 168 h of reaction, Sb(V) removal efficiency in iron + IOB + SRB system was 99.98%, which was higher than that in pure scrap iron, iron + IOB, and SRB system. SEM-EDX, XRD, and XPS analysis of reaction products indicated that scrap iron could be oxidized to amorphous Fe2O3 and FeOOH completely in biotic systems, providing favorable anaerobic condition for SRB. At the end of experiment, 80.35% of Sb(V) in iron + IOB + SRB system was adsorbed by biogenetic iron oxides, and 19.65% was bio-reduced as Sb2S3. Moreover, long-term treatment of antimony mine wastewater by scrap iron inoculated with IOB and SRB increased the bacterial abundance in the bioreactor, and Sb(V) removal ability of iron reached 180 mg(Sb)/g (Fe) after running for 310 days. The study provides an efficient method to remove Sb(V) from mine wastewater and might open a new way for the application of iron fillings.

Repertoire analysis of memory T-cell receptors in Japanese patients with inflammatory bowel disease.

Background and AimThe T‐cell receptor (TCR) repertoire was assessed in response to various antigens and was considered to be associated with the pathogenesis of inflammatory bowel disease (IBD). Thus, we performed TCR repertoire analysis to examine the pathology of IBD from changes in the TCR repertoire of memory T cells in the intestinal lamina propria mononuclear cells (LPMCs) and peripheral blood mononuclear cells (PBMCs) of patients with IBD.MethodsLPMCs in the surgical specimens and PBMCs were isolated from 12 patients with IBD (5 patients with ulcerative colitis [UC] and 7 patients with Crohn's disease [CD]). PBMCs were collected from 10 healthy individuals as controls. Comprehensive TCR sequence analyses of adaptor‐ligation polymerase chain reaction (PCR) products were performed using MiSeq.ResultsThe diversity of TCR‐α and TCR‐β in PBMCs was significantly lower in patients with IBD than that in controls (P = 0.00084 and 0.0013, respectively). Comparisons of TCR diversity in LPMCs and PBMCs between CD and UC showed that the diversity in LPMC was not affected by diseases, whereas that in PBMCs was significantly lower in CD than in UC (P = 0.045 and 0.049, respectively). Some TCR clones may have shown a specific increase or decrease in CD and UC, and many clones were common to both LPMCs and PBMCs in the same patients.ConclusionThe diversity of TCR clones in LPMCs and PBMCs in patients with IBD was significantly lower than that of PBMCs in controls. TCR diversity in PBMCs was particularly low in patients with CD.

Catalytic Conversion of Isopropanol on a Heteropoly Acid–η-Aluminum Oxide System

The results from catalytic conversion of isopropanol on a heteropoly acid–η-aluminum oxide system are discussed. It is established that modification increases its activity and selectivity toward oxygen-containing products. Based on a comparative analysis of reaction products, it is shown that the active sites of unmodified η-aluminum oxide consist only of strong Lewis acid sites (LASes) and strong Lewis basic sites (LBSes), represented predominantly by Bronsted basic sites (BBSes) after modification with a heteropoly acid. The synthesized systems are characterized via X-ray diffraction, scanning electron microscopy, elemental analysis, and IR spectroscopy. The set of obtained results shows that the Keggin structure decomposes as it interacts with the basic oxide to form heteropoly anions. Due to their negative charge, these interact with the electron-accepting Lewis acid sites to form a surface–ligand complex. This then begins to act as a new Bronsted base, due to its uncompensated negative charge.

Rutinosidase from Aspergillus niger: crystal structure and insight into the enzymatic activity.

Rutinosidases (α-l-rhamnosyl-β-d-glucosidases) catalyze the cleavage of the glycosidic bond between the aglycone and the disaccharide rutinose (α-l-rhamnopyranosyl-(1→6)-β-d-glucopyranose) of specific flavonoid glycosides such as rutin (quercetin 3-O-rutinoside). Microbial rutinosidases are part of the rutin catabolic pathway, enabling the microorganism to utilize rutin and related plant phenolic glycosides. Here, we report the first three-dimensional structure of a rutinosidase determined at 1.27-Å resolution. The rutinosidase from Aspergillusniger K2 (AnRut), a member of glycoside hydrolase family GH-5, subfamily 23, was heterologously produced in Pichiapastoris. The X-ray structure of AnRut is represented by a distorted (β/α)8 barrel fold with its closest structural homologue being an exo-β-(1,3)-glucanase from Candidaalbicans (CaExg). The catalytic site is located in a deep pocket with a striking structural similarity to CaExg. However, the entrance to the active site of AnRut has been found to be different from that of CaExg - a mostly unstructured section of ~40 residues present in CaExg is missing in AnRut, whereas an additional loop of 13 amino acids partially covers the active site of AnRut. NMR analysis of reaction products provided clear evidence for a retaining reaction mechanism of AnRut. Unexpectedly, quercetin 3-O-glucoside was found to be a better substrate than rutin, and thus, AnRut cannot be considered a typical diglycosidase. Mutational analysis of conserved active site residues in combination with insilico modeling allowed identification of essential interactions for enzyme activity and helped to reveal further details of substrate binding. The protein sequence of AnRut has been revised. DATABASES: The nucleotide sequence of the rutinosidase-encoding gene is available in the GenBank database under the accession number MN393234. Structural data are available in the PDB database under the accession number 6I1A. ENZYME: α-l-Rhamnosyl-β-d-glucosidase (EC3.2.1.168).

Study of the reaction of iodoarylation of phenylacetylene by benzenediazonium tetrafluoroborate

Anion-arylation reaction, as well as its partial case – Meerwein arylation reaction, is a valuable tool for construction of practically important compounds. Such reactions are mainly catalyzed by transition metals. In the same time, iodo-arylation is self-catalyzed reaction and does not require utilization of eco-unfriendly heavy-metal containing catalysts. However, there are only several reports concerning to this topic. In order to shed more light on the nature and distributions of products of this reaction, herein we thoroughly investigated iodoarylation reaction of phenylacetylene by benezenediazonium tetrafluoroborate in the presence of lithium iodide. Reaction has been performed at 0‑5°C in DMF. For analysis of reaction products and its ratio GC‑MS analysis have been applied. Seven main products of this reaction have been found. In the reaction mixture typical product of Sandmeyer reaction – iodobenzene (33.9 %) has been identified. Although in course of the reaction formation of dimethylaminobenzene (6.5 %) take place. Probably, formation of last is a result of benzene radical attack on the solvent (DMF). In the same time, formation of diiodostyrene (10.2 %) in reaction mixture was predictable, because it is well known that iodine anion easily can be oxidized by arenediazonium salts to elemental iodine, which further reacts with starting phenylacetylene. Further, orto- and para-iodobiphenyls (8.7 and 4.1 %, respectively) have been identified in the reaction mixture. Formation of such products was unexpected, however can be explained as subsequent arylation by Gomberg-Bachmann-Hey type reaction of formed iodobenzene. Finally, desired E- and Z-iodostilbenes have been formed in 36.6 % total yield with E/Z ratio close to 3:1. In conclusion, products of iodo-mediated reaction of benzenediazonium tetrafluoroborate with phenylacetylene in presence of lithium iodide have been investigated by GC‑MS analysis. Possible ways of formation of all identified compounds have been suggested. Key words : iodo-arylation, iodostilbenes, arenenediazonium salts, phenylacetylene, chromato-mass spectrometry.

Reaction Product Analysis of the Most Active “Inactive” Material in Lithium-Ion Batteries—The Electrolyte. II: Battery Operation and Additive Impact

Electrolyte decomposition of lithium-ion battery as a consequence of thermal stress was investigated in Part 1 of this two-part study. The focus of Part 2 is on the influence of the battery cell op...

Reaction Product Analyses of the Most Active “Inactive” Material in Lithium-Ion Batteries—The Electrolyte. I: Themal Stress and Marker Molecules

The identification of decomposition products in lithium-ion battery (LIB) electrolytes enables a better understanding of interphase layer compositions at the electrode||electrolyte interfaces and o...

Gas chromatography/mass spectrometry analysis of reaction products of sulfur mustards with phenol.

Screening of chemicals related to chemical weapons convention including their all possible degradation and reaction products in environmental samples is important in the organization for prohibition of chemical weapons verification process. Sulfur mustards, commonly known as blistering agents, are included in schedule 1 chemicals of chemical weapons convention. Because of the presence of chlorine atoms in sulfur mustards, they are highly reactive and prone to react with other organic molecules such as phenols to produce corresponding reaction products. Thus, it is important to screen for not only the sulfur mustards but also their reaction products for verification process. The sulfur mustards and their degradation products have been routinely analyzed by gas chromatography/mass spectrometry method, however, the methods are yet to establish for the reaction products. In this study, the reaction products of the sulfur mustards with phenol (compounds 1-7) were studied by gas chromatography/mass spectrometry under electron ionization and chemical ionization conditions. The EI spectra of 1-7 displayed molecular ion and characteristic fragments that provided structure information. Mostly the fragment ions were due to homolytic cleavages involving C-O, C-S, and C-C cleavages. The methane or isobutane CI spectra showed M+., [M + H]+, and [M - H]+ ions including reagent specific adduct ions. The CI spectra also showed other adduct ions formed by association of analyte molecule with its most abundant fragment ion. The gas chromatography/retention index values were also calculated, which support unambiguous identification of targeted molecules in suspected environmental samples. The method was demonstrated for detection of the targeted molecules spiked in soil samples.

Proteases Immobilization for In Situ Time-Limited Proteolysis on MALDI Chips

A large number of different enzyme immobilization techniques are used in the field of life sciences, clinical diagnostics, or biotechnology. Most of them are based on a chemically mediated formation of covalent bond between an enzyme and support material. The covalent bond formation is usually associated with changes of the enzymes’ three-dimensional structure that can lead to reduction of enzyme activity. The present work demonstrates a potential of an ambient ion-landing technique to effectively immobilize enzymes on conductive supports for direct matrix-assisted laser desorption/ionization (MALDI) mass spectrometry analyses of reaction products. Ambient ion landing is an electrospray-based technique allowing strong and stable noncovalent and nondestructive enzyme deposition onto conductive supports. Three serine proteolytic enzymes including trypsin, α-chymotrypsin, and subtilisin A were immobilized onto conductive indium tin oxide glass slides compatible with MALDI mass spectrometry. The functionalized MALDI chips were used for in situ time-limited proteolysis of proteins and protein–ligand complexes to monitor their structural changes under different conditions. The data from limited proteolysis using MALDI chips fits to known or predicted protein structures. The results show that functionalized MALDI chips are sensitive, robust, and fast and might be automated for general use in the field of structural biology.

Zurückziehung: Produktion von Methanol und Ethanol aus Methan in einem einzigen Reaktor mit einem Nickeloxid auf Ceroxid‐Zirconiumoxid‐Katalysator

The above article from Angewandte Chemie, published online on 8 August 2017 in Wiley Online Library (wileyonlinelibrary.com, DOI: 10.1002/ange.201704704), and in print in Volume 129, pp. 14064–14069, has been retracted by agreement between the author, Dr. Carsten Sievers, the journal Editor in Chief, Dr. Neville Compton, and John Wiley and Sons Ltd. The retraction has been agreed upon following the explanation by Carsten Sievers that this article contained data that are irreproducible. After recent efforts to replicate the continuous flow experiments, the authors found that several mistakes regarding the calibration of feed streams and the analysis of reaction products had been made in the reactivity experiments reported in the original Communication.

Spectroscopy for model heterogeneous asymmetric catalysis.

Heterogeneous catalysis has vastly benefited from investigations performed on model systems under well-controlled conditions. The application of most of the techniques utilized for such studies is not feasible for asymmetric reactions as enantiomers possess identical physical and chemical properties unless while interacting with polarized light and other chiral entities. A thorough investigation of a heterogeneous asymmetric catalytic process should include probing the catalyst prior to, during, and after the reaction as well as the analysis of reaction products to evaluate the achieved enantiomeric excess. I present recent studies that demonstrate the strength of chiroptical spectroscopic methods to tackle the challenges in investigating model heterogeneous asymmetric catalysis covering all the abovementioned aspects.

The potency of γ-valerolactone as bio-sourced polar aprotic organic medium for the electrocarboxlation of furfural by CO2

The reductive electro-carboxylation of furfural at a Pt/C electrode was studied in a bio-sourced γ-valerolactone (GVL) solvent using linear scan voltammetry, in situ infrared spectroscopy (in situ FTIRS) under electrode potential control and by chrono-amperometry (CA) with analysis of reaction products. In situ FTIRS measurements indicated that GVL reacted at the electrode in the absence of furfural and/or of CO2, while the solvent became much less reactive in the presence of furfural and/or of CO2. It was also found that CO2 was activated from the high cathodic potential of −0.8 V vs SCE (saturated calomel electrode) and that it reacted with furfural. CA measurements at a cell voltage of 2.0 V, corresponding to a cathode potential higher than −1.66 V vs. SHE (standard hydrogen electrode), were performed for 24 h in the presence of CO2 at the cathode. Gas chromatography coupled with mass spectroscopy (GC–MS) analyses revealed the formation of 2-hydroxyvaleric acid (reaction between GVL and residual water) and oxalic acid (coupling reaction of CO2) as main reaction products in the absence of furfural in the reaction medium. In the presence of furfural in the reaction medium, 2-hydroxyvaleric acid and oxalic acid were detected as traces, whereas a new carboxylated specie, 2-furyl(hydroxy)acetic acid, corresponded by far to the main reaction product (ca. 82%). 1H NMR and LC-MS analyses confirmed the formation of this last compound. Under the experimental conditions described in this article, the electro-activation of CO2 could be performed at high cathode potential in GVL, leading in presence of furfural to the formation of the α-hydroxy-acid.

Nanostructure and Mechanism of Metal Deposition by a Laser‐Induced Photothermal Reaction

AbstractLaser‐induced photothermal reaction of metal ions is a promising one‐step method for production of conductive micropatterns for electronic devices and sensors. However, the mechanism that governs the process in which thermally activated materials are deposited on a substrate is not clear. Here, light is shed on the mechanism through systematic analysis of photothermal reaction products forming iron oxide and silver at different interfaces. Examination of the nanostructure of deposits on a substrate using high‐resolution transmission electron microscopy and selected area diffraction pattern analysis reveals a combination of both amorphous and crystalline moieties. It is found that focusing the laser inside the solution leads to exclusive formation of crystalline products, while focusing at the liquid/air interface leads to formation of amorphous products due to kinetic considerations. Ring‐shaped microstructures observed on the substrate indicate that microbubbles are involved in the deposition. The findings suggest that crystalline nanoparticles formed in solution are pinned to the base of the microbubbles. These stationary deposits absorb the laser light, resulting in extensive local heating, which leads to a fast thermal‐reaction of the metal ions that are added as amorphous nanostructures. The presence of both crystalline and amorphous nanostructures therefore results from two different mechanisms.

Hydration and strength development in blended cement with ultrafine granulated copper slag.

This study aims at evaluating the effect of ultrafine granulated copper slag (UGCS) on hydration development of blended cement and mechanical properties of mortars. The UGCS with the median particle size of 4.78 μm and BET surface area of 1.31 m2/g was used as a cement replacement to prepare blended cements. Hydration heat emission of blended cement and mechanical performance of mortars were investigated by using isothermal calorimetry and strength tests, respectively. X-ray diffraction (XRD), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM) were applied to the analysis of pozzolanic reaction and hydration products. The results illustrate that UGCS has influence on the hydration heat evolution of blended cement due to its filler effect and pozzolanic reaction. The cumulative hydration heat of blended cement is reduced by partial cement replacement with UGCS. The test mortar prepared by using blended cements with 30 wt. % UGCS shows a retardation of strength development with a low value at early ages (7 days) and a rapid growth at later ages (28 days). The 90-day compressive strength of test mortar is 45.0 MPa close to that of the control mortar (49.5 MPa). The obtained results from XRD and TGA analysis exhibit an increase in calcium hydroxide (CH) consumption and calcium silicate hydrates (C–S–H) formation in blended cement pastes with curing time. The cement replacement with UGCS induces changes in microstructure of blended cement paste and chemical composition of hydration products.

Resistance of selected aggregates from igneous rocks to alkali-silica reaction: verification

The paper presents investigations into the reactivity of aggregates from igneous rock, carried out in accordance with the procedures contained in the GDDKiA General Technical Specification "Concrete pavements". The aim of the investigations was evaluation of the suitability of the aggregates for road structures and pavements built using cement based concrete technology. Aggregates produced from extrusive rocks (basalt, melaphyre and porphyry) and from intrusive rocks (granite and gabbro) were analysed. The mineral composition of the aggregates was evaluated with regard to their reactive SiO2 content. Expansion tests on mortar bar and concrete prism specimens with analysed aggregates and a microscopic analysis of the alkali-aggregate reaction products were carried out. A considerable amount of reactive minerals: chalcedony, tridymite and microcrystalline quartz and volcanic glass were found in the grains of the porphyry and melaphyre aggregates. On the basis of the conducted investigations the two aggregates made of igneous rocks (melaphyre and porphyry) were classified into category R1 (moderately reactive). The basalt aggregate, the granite aggregate and the gabbro aggregate were assigned to category R0 (non-reactive).

РЕЗУЛЬТАТЫ ИССЛЕДОВАНИЯ НАЧАЛЬНОГО ЭТАПА ОКИСЛЕНИЯ АУСТЕНИТНОЙ СТАЛИ 12Х18Н10Т В ВОДЯНОМ ПАРЕ

The paper presents the results of the study of the initial stage of oxidation of austenitic steel 12X18H10T in water vapor, which were obtained using a method of research of thin surface layers of steel, based on the analysis of nuclear reaction products in the interaction of oxygen with accelerated ion beams. Austenitic 18 % chromium steel 12X18H10T is one of the structural steels used in reactor installations with heavy liquid metal coolant (HLMC) in the region is relatively high (T<350 °C) temperatures. In test benches and experimental installations the temperature area of use of this steel is much wider. Studies of this steel, especially in the field of low temperatures or short time intervals of exposure of samples, where there are significant methodological difficulties, are of some scientific interest. In addition, the study of the oxidation of structural steels directly in gaseous media, including water vapor, are of great practical importance. It is because these modes of oxidation are used as special technological operations of formation of oxide films on the individual elements and the equipment of the first circuits of nuclear power plant (NPP) with HLMC on the basis of lead and its alloys.

Origins of N-formylmethamphetamine and N-acetylmethamphetamine in methamphetamine produced by the hydriodic acid and red phosphorus reduction of pseudoephedrine

N-Formylmethamphetamine (FMA) and N-acetylmethamphetamine (AMA) are suspected to be trace by-products in methamphetamine (MA) produced from pseudoephedrine using the Nagai reaction. However, these amides are not rational by-products of the Nagai reaction.FMA is an intermediate in the synthesis of MA using the Leuckart reaction. However, as there is the possibility that FMA is a by-product of the Nagai reaction, the significance of FMA as an indicator of the Leuckart reaction has been debated. It is therefore important to establish whether AMA and especially FMA are by-products of the Nagai reaction and thus establish their significance as synthetic route markers.From the work presented here, FMA is a by-product of the Nagai reaction but the mechanism by which FMA arises could be not determined.AMA was also shown to be a by-product of the Nagai reaction, most likely due to reaction between MA and phenyl-2-propanone (P-2-P), itself a by-product of the Nagai reaction. Furthermore, during GC analysis of Nagai reaction products, MA has been shown to react with P-2-P or ethyl acetate in the injector to form AMA.Caution is recommended if the relative abundance of AMA and/or FMA are used as a basis for determining whether MA samples have a common source or not. Furthermore, it is clear that FMA cannot be considered to be a route-specific by-product for the Leuckart reaction – it is the abundance of FMA in a reaction mixture or profile, not simply its presence, that points to the involvement of the Leuckart reaction.