Simultaneous Formation Research Articles

Simultaneous kinetics formation of heterocyclic amines and polycyclic aromatic hydrocarbons in phenylalanine model system

A combination of chemical model system with kinetics study was used to investigate the simultaneous formation of heterocyclic amines (HCAs) and polycyclic aromatic hydrocarbons (PAHs). Heating a mixture of phenylalanine, creatinine, and glucose at a commonly practiced household cooking time and temperature successfully differentiated the rate formation (k) of HCAs and PAHs. The good fit suggested that the simultaneous formation was an endothermic bimolecular reaction, and followed the first-order model. The rate formation (k) of HCAs and PAHs significantly increased with increasing heating time and temperature. Only 2-amino-3,4-dimethylimidazo[4,5-f]quinoline (MeIQ) and 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) showed degradation rate (k) at higher heating temperatures of 210 °C and 240 °C respectively. Increasing phenylalanine concentration increased the possibility of higher HCAs and PAHs formation. The activation energy (Ea) showed that heating phenylalanine mixture resulted in higher rate of formation of 2-amino-3-methylimidazo[4,5-f]quinoline (IQ) and benzo[b]fluoranthen (BbF).

Kinetics of the Formation of Bimetallic Compounds and the Distribution of Energy Components in the Explosion Welding Process

The article is devoted to the study of the kinetics of packet formation and energy distribution in the process of explosion welding. The results of experimental determination of the components of the total energy balance during explosion welding and their influence on obtaining a given part profile are presented. The kinetics of the package motion during explosion welding with simultaneous formation of a bimetallic billet with a cylindrical profile is shown.

Electrocatalytic Oxygen Reduction Reaction at Silver Nanoparticles (AgNPs) Electrode in Neutral Solution: 5-amino-2-naphthalene-sulfonic acid (ANS) as a Reducing Agent for AgNPs

We report electrocatalytic oxygen reduction reaction (ORR) at silver nanoparticle (AgNPs) electrodes. The AgNPs was obtained in a general one-pot synthesis using 5-amino 2-naphthalene-sulfonic acid (ANS) as a reducing agent in aqueous and room-temperature conditions. The simultaneous formation of AgNPs and oxidation of ANS were monitored by UV–vis spectroscopy. The surface morphology of AgNPs was characterized by transmission electron microscopy, which revealed that AgNPs appeared as a sphere. The average size of AgNPs was found to be 16 ± 2 nm. Furthermore, the chemical identity of the nanostructures was established using X-ray photoelectron spectroscopy and X-ray diffraction. The prepared AgNPs showed electrocatalytic activity for the reduction of oxygen in neutral pH. Rotating disk electrode voltammetry was used to elucidate the kinetics of ORR at the AgNPs electrode. These results reveal that oxygen reduction reaction at AgNPs-PANS electrode involved direct four-electron pathways.

New Holocene formal subdivision – application for the Russian Arctic

The subject of the study is a new formal subdivision of Holocene epoch applied to the northern regions of the Russian permafrost. The following criteria are considered: criteria for the modern allocation of three calendar periods of the Holocene; comparison with the Blitt-Sernander scheme; comparison with the three-term division of the Holocene for the Russian Arctic, proposed by Yu.K.Vasilchuk. In 2008, the International Commission on Stratigraphy (IUGS) established the boundary between the Holocene and the Neo-Pleistocene at the turn of about 11,700 calibrated years ago (cal. l. n.). In 2018, in addition to the well-known Blitt-Sernander division, the Holocene was divided by IUGS into three tiers: Greenland (from 11,700 to 8,200 cal. years ago), North Grippian (from 8200 to 4200 cal. years ago) and Meghalayan (beginning 4200 cal. years ago). The features of the development of polygonal vein arrays during three Holocene periods were established and the average January air temperatures for four key regions of the Russian cryolithozone were reconstructed - the north of the European part of Russia, the north of Western Siberia, the lower reaches of the Kolyma River and the east of Chukotka. It is shown that, taking into account the new division of the Holocene, the Greenland and North Grippian periods of the Holocene (between 11.7 and 4.2 thousand years ago) are the stage of the most active development of peat bogs and the simultaneous formation of re–vein ice in them. The Meghalayan Holocene period was characterized by a marked decrease in the development of peatlands, but syngenetic growth of re-vein ice continued within the emerging floodplains and laids, especially within the torn-off areas. The reconstructed average January air temperatures for four key regions of the Russian cryolithozone showed that the Greenland and North Grippian periods of the Holocene were characterized by slightly higher values (on average 1-2 °C higher) than the Meghalayan, with the exception of eastern Chukotka, for which an increase in the average January air temperature during the Meghalayan period was noted.

Recommendations for the Design of an Installation for Wind Energy Conversion into Electrical Energy

The article provides an overview of the current state of renewable energy sources. The generation capacities of the leading countries in terms of renewable energy sources are briefly described. Based on the potential of wind energy, as well as taking into account the hidden potential of vibrational energy, a plant for converting wind energy into electrical energy is proposed. The feature of the installation is simplicity of design and availability of materials. This paper describes the advantages of the installation and the recommended minimum dimensions. Recommendations for installing transmitters inside the unit are also described. The correct location of the transducers allows to achieve the mode of simultaneous vortex formation, which, in turn, leads to an increase in the efficiency of the installation.

Transforming Escherichia coli Proteomembranes into Artificial Chloroplasts Using Molecular Photocatalysis.

During the light‐dependent reaction of photosynthesis, green plants couple photoinduced cascades of redox reactions with transmembrane proton translocations to generate reducing equivalents and chemical energy in the form of NADPH (nicotinamide adenine dinucleotide phosphate) and ATP (adenosine triphosphate), respectively. We mimic these basic processes by combining molecular ruthenium polypyridine‐based photocatalysts and inverted vesicles derived from Escherichia coli. Upon irradiation with visible light, the interplay of photocatalytic nicotinamide reduction and enzymatic membrane‐located respiration leads to the simultaneous formation of two biologically active cofactors, NADH (nicotinamide adenine dinucleotide) and ATP, respectively. This inorganic‐biologic hybrid system thus emulates the cofactor delivering function of an active chloroplast.

Problems and Perspectives in Pension System: Case of Baltic States

In all states of European Union reforms in pension system are being made, likewise in Latvia. Demographic and economic problems that are occurred forces pension reforms to be made. New developed pension reform includes different processes, like – formation of financial equilibrium between incomes and costs, limit performance in going early in pension, increasing of age of going in pension, rebalancing between men and women. Simultaneous formation of state and private pension systems could prevent some of the major drawback in system of pension that undermines the pension system of nowadays. Unfortunately the high social security contributions of state sector persons lacks of money, for deposit in private pension funds. Using method of logic synthesis, as the target authors nominated to examine problems of pension systems in the Baltic States, as well as similarities and divergences in problems and perspectives, with the status of private pension funds in accumulating pension system.

Fabrication of Bi12GeO20/Bi2S3 hybrids with surface oxygen vacancies by a facile CS2-mediated manner and enhanced photocatalytic performance in water and saline water

A series of biphasic hybrids Bi12GeO20/Bi2S3 containing surface oxygen vacancies (OVs) were constructed through a facile CS2-mediated manner. Microstructural, morphological, optical, and electrochemical features of relevant samples were thoroughly researched by a sequence of analytical techniques. The presence of in-situ generated Bi2S3 phase and simultaneous formation of surface OVs were confirmed in these n-p heterojunction hybrids. As soon as exposed to visible light, as-achieved hybrids provided reinforced photocatalytic removal upon dye Rhodamine B (RhB) and antibiotic tetracycline hydrochloride (TC) in comparison to bare Bi12GeO20, chiefly crediting to augmented visible-light harvesting, efficient spatial separation of charge carriers over interface by n-p heterojunction with well-matched band structures, and presence of sufficient surface OVs. Moreover, reactive Cl species and Cl-contained intermediates were undetectable in saline water, therefore the significantly enhanced catalytic efficiencies in saline water than in water were mainly attributed to different degradation routes by ultraviolet-visible (UV–Vis) absorption, three-dimension excitation emission matrix fluorescence (3D-EEM), and high performance liquid chromatograph-mass (HPLC-MS) spectra, further ascribing to partial consumption of holes by Cl- anions and boosted generation of superoxide (∙O2–) and hydroxyl (∙OH) radicals. Eventually, a reasonable photocatalysis mechanism was proposed in a Z-scheme model by these robust hybrids with favorable recyclability and structural steadiness. This work provided promising Bi12GeO20/Bi2S3 hybrids with appropriate physicochemical properties and reinforced photocatalytic degradation of organic contaminants in saline water without the generation of toxic Cl-containing intermediates.

Antifatigue Hydration-Induced Polysaccharide Hydrogel Actuators Inspired by Crab Joint Wrinkles.

Joint wrinkles in animals facilitate frequent bending and contribute to the duration of the joint. Inspired by the morphology and function of joint wrinkles, we developed a bionic hydration-induced polymeric actuator with constructed wrinkles at the selected area. Specifically, we adopt electrical writing to create defined single and double cross-linking regions on chitosan (CS) hydrogel. The covalent cross-linking network was constructed by electrical writing-induced covalent cross-linking between CS chains and epichlorohydrin. Subsequent treatment of sodium dodecyl sulfate allows electrostatic cross-linking at the unwritten area with the simultaneous formation of surface wrinkles. The resulting single and double cross-linking hydrogel demonstrates spontaneous deformation behaviors by the influx and efflux of H2O to the electrostatic cross-linking domain under different ion concentrations. Importantly, the wrinkle structure endows the hydrogel with extraordinary antifatigue bending performance. By regulating the surface morphology and spatial cross-linking, we can design novel biomimetic polysaccharide hydrogel actuators with fascinating functions.

Photoinduced reaction of dichlorosilylene with acetylene: Matrix isolation FTIR spectroscopic study

A matrix-isolation FTIR study of the reaction between SiCl2 and acetylene showed that at low temperatures, it stops at the stage of complexation between the reactants. This made it possible to examine a photochemical version of this reaction, which led to the simultaneous formation of 1,1-dichloro-1-silacycloprop-2-ene and 3,3-dichloro-3-silaprop-1-yne in comparable yields in contrast to the thermal reaction, which, according to quantum chemical calculations carried out here, results in the formation of 1,1-dichloro-1-silacycloprop-2-ene as the only primary product.

Switchable hydrophilic solvent-based dispersive liquid-liquid microextraction coupled with high-performance liquid chromatography for the determination of four types of sulfonylurea herbicides in soils.

In this study, switchable hydrophilic solvent-based dispersive liquid-liquid microextraction coupled with high-performance liquid chromatography was developed for the determination of four sulfonylurea herbicides in soils. For the first time, the sample pretreatment was achieved due to the similar acid-base status of sulfonylurea herbicides and switchable hydrophilic solvent. In the extraction step, sulfonylurea herbicides were extracted as anions and transferred to an alkaline solution with switchable hydrophilic solvent anions. In the concentration step, two types of anions were transformed to their molecular state after the aqueous solution was acidified. In addition, the dispersion and microextraction processes were completed efficiently with the simultaneous formation of analytes and extractants. The factors affecting the extraction performance were optimized. Under the optimized conditions, good linearity was observed for each herbicide with correlation coefficients ranging from 0.9952 to 0.9978. The limits of detection were in the range of 0.1-0.2 μg/g. Moreover, the relative recoveries of the sulfonylurea herbicides at spiking levels of 0.5, 1, and 1.5 μg/g in soil samples were between 75 and 111% (relative standard deviations: 0.4-11.4%). Therefore, the proposed method in this study could be successfully applied to the analysis of four types of sulfonylurea herbicides in soil samples.

Synthesis of self-regenerating NiAl-Al2O3 composite coatings

The aluminothermic reactions involved either in the mixtures or the stack of NiO and Al powders were elucidated in a previous work (Troncy et al., 2020) [1]. The present work now investigates the formation of potential self-regenerating coatings using the aluminothermic reaction between nickel oxide and aluminum. The use of this exothermic reaction allows the simultaneous formation of both alumina and nickel aluminides. The coatings were obtained by first pre-oxidizing the nickel substrate, then spraying an aluminum slurry before applying an adequate heat treatment. The most promising self-regenerating coatings display a first composite layer, made of an intermetallic compound (Al3Ni or NiAl) and alumina, and a second layer with a higher concentration of oxide. The first layer is expected to play the role of an Al reservoir coating and the second one that of a diffusion barrier to slow down the Al flux to maintain the Al reservoir in the coating. The effects of preoxidation time and of temperature on the resulting coating microstructures are discussed as a function of time.

Applied stress anisotropy effect on melting of tungsten: molecular dynamics study

Atomic-level insight into pre- and post- melting phenomena under complex stresses spanning compression, tension, and shearing in refractory metals is critical. The exploration of high temperature and melting behavior in tungsten under magnitude- and orientation-dependent uniaxial and biaxial compression and tension, approaching pure shear stresses was thoroughly investigated by molecular dynamics using extended Finnis-Sinclair potential. Using equilibrium solid-liquid coexistence simulations, we demonstrated the enhancement (reduction) of the melting point temperature Tm taking place with the increase of applied compression (tension) stress magnitudes, reaching a minimum under pure shear stress. Explored heating and melting behaviors under various stress types, magnitudes, and orientations were well supported by the corresponding trends in radial distribution function g(r) and Lindemann index δ. The highest resistance to melting was found under uniaxial compression likely due to bonds stiffening. On the other hand, the highest compliance to melting was revealed under pure shear stress, triggered by the accelerated vibrational instability and destruction of the bcc crystalline order driven by simultaneous shear deformation and formation of fcc and hcp phases.

Negative-pressure wound therapy is effective for peritoneal dialysis catheter exit-site management in the early postoperative period

Peritoneal dialysis (PD) catheter exit-site care is critically important for the prevention of catheter-related infections (CRIs) and subsequent peritonitis. The postoperative management of the site is particularly essential because it has an open wound that is always adjacent to a PD catheter tube. This study aimed to examine the effectiveness of negative-pressure wound therapy (NPWT) for postoperative PD catheter exit sites. Thirty patients with end-stage renal disease who underwent simultaneous PD catheter insertion and exit-site formation were randomly assigned to receive NPWT (NPWT group) or conventional dressing (non-NPWT group) for the first seven postoperative days. The exit-site scores on the seventh postoperative day was lower in the NPWT group than in the non-NPWT group (p = 0.0049). Analysis of variance F statistic for the effect of NPWT over 180 days was highly significant (11.482595, p = 0.007). There were no statistically significant differences between the time to first CRI and PD-related peritonitis between the two groups. There was one case of CRI with relapsing peritonitis and catheter loss in the non-NPWT group. These findings demonstrate the association between NPWT and low exit-site score. NPWT can be recommended for the management of PD catheter exit sites in the early postoperative period.

Enantioselective one-carbon expansion of aromatic rings by simultaneous formation and chromoselective irradiation of a transient coloured enolate.

Enantioenriched seven-membered carbocycles are motifs in many molecules of structural and biological interest. We report a simple, practical, transition metal-free and mechanistically unusual method for the enantioselective synthesis of substituted cycloheptatrienes. By forming a coloured enolate with an appropriate absorption band and selectively irradiating in situ, we to initiate a tandem, asymmetric anionic and photochemical ring expansion of readily accessible N-benzylbenzamides. The cascade of reactions leading to the products entails enantioselective benzylic deprotonation with a chiral lithium amide, dearomatizing cyclization of the resulting configurationally defined organolithium to give an extended amide enolate, and photochemically induced formal [1,7]-sigmatropic rearrangement and 6π-electrocyclic ring-opening – the latter all evidently being stereospecific – to deliver enantioenriched cycloheptatrienes with embedded benzylic stereocentres.

Study of the temperature dependence of a carbidized layer formation on the tungsten surface under plasma irradiation

The paper considers a method of tungsten surface carbidization using a beam-plasma discharge (BPD), which was implemented in a plasma-beam installation (PBI). The advantage of this method is to create conditions for chemical reactions and physical processes as close as possible to those possible in thermonuclear installations. The BPD makes it possible to generate plasma using different working gases. Methane was used as a plasma-forming gas. The working gas pressure in a chamber was (1,3–1,4)·10–1 Pa. The temperature dependence of the carbidized layer formation on the tungsten surface under plasma irradiation was determined in the temperature range of 700 °C–1700 °C. The formation of tungsten carbides in surface layers was confirmed by SEM and x-ray diffraction analysis. It was found that interaction between tungsten and methane in a wide temperature range can proceed with simultaneous or sequential formation of the carbide phases W2C and WC.

Iminyl radical-triggered relay annulation for the construction of bridged aza-tetracycles bearing four contiguous stereogenic centers.

Bridged tetracyclic nitrogen scaffolds are found in numerous biologically active molecules and medicinally relevant structures. Traditional methods usually require tedious reaction steps, and/or the use of structurally specific starting materials. We report an unprecedented, iminyl radical-triggered relay annulation from oxime-derived peresters and azadienes, which shows good substrate scope and functional group compatibility, and can deliver various bridged aza-tetracyclic compounds with complex molecular topology and four contiguous stereogenic centers (dr > 19 : 1) in a single operation. This transformation represents the first example of trifunctionalization of iminyl radicals through simultaneous formation of one C–N and two C–C bonds. DFT calculation studies were conducted to obtain an in-depth insight into the reaction pathways, which revealed that the reactions involved an interesting 1,6-hydrogen atom transfer process.

Liposome Preparation by 3D-Printed Microcapillary-Based Apparatus.

Liposomal encapsulation serves as the basis for the engineering of biomimetic and novel synthetic cells. Liposomes are normally formed using such methods as thin film rehydration (TFH), density-mediated reverse emulsion encapsulation (REE), or one of many microfluidics-based approaches-with the latter of these two methods being used mainly for the encapsulation of various lumen constituents such as cell-free protein expression reactions. Here, we describe the simultaneous formation and encapsulation of liposomes and various cell-mimetic lumen chemistries, respectively, using a 3D-printable microcapillary-based microfluidics device based off of the droplet-shooting and size-filtration (DSSF) liposome preparation method.

Characterization of a coumarin C-/O-prenyltransferase and a quinolone C-prenyltransferase from Murraya exotica.

Prenyltransferases (PTs) play important roles in the biosynthesis and structural diversification of natural products. In the present study, two new PTs were characterized from a medicinal plant Murraya exotica. MePT1 unprecedentedly catalyses the formation of two C-geranylated products 8/6-C-geranylumbelliferone together with a trace product 7-O-geranylumbelliferone from umbelliferone. MePT2 regio-specifically catalyses the formation of C-3 dimethylallylated products from quinolone alkaloids. This is the first report that a plant PT catalyses the simultaneous formation of C- and O-prenylated products, and a plant PT specifically utilizes quinolone alkaloids as prenyl acceptors. The results not only provide important insight into the functional diversity of plant PTs and the biosynthesis of the prenylated coumarins, quinolone and carbazole alkaloids in Murraya plants, but also pave the way for the overproduction of the prenylated coumarins and alkaloids using metabolic engineering approaches.

МОДЕЛЬ ОБУЧЕНИЯ СИНТЕТИЧЕСКИМ ВИДАМ РЕЧЕВОЙ ДЕЯТЕЛЬНОСТИ С ПРИМЕНЕНИЕМ МЕТОДА «МОБИЛЬНОЕ ВИДЕО»

Currently, there are a lot of writing and talking about the optimization of the educational process using new technologies, models, methods, techniques, forms, the appearance of which is conditioned by the new reality, the modern educational environment. We offer a model of learning synthetic types of speech activity, in which the method of “mobile video” is applied, for use in teaching Russian to foreign students. The development of the model of learning synthetic types of speech activity is due to the fact that the modern educational space dictates a new approach to the choice of educational material, as which are increasingly used various texts of online discourse. Thus, the search for ways to work with texts of online discourse leads to the creation of new effective methods and techniques (for example, the “mobile video” method), which allow to create a flexible model, it is designed to provide one lesson with skills for different types of speech. “Mobile video” is defined by us as a method allowing the teacher to involve the student in “live”, real communication, erasing the boundaries between speaking, listening, reading and writing. Therefore, the basis of the model of learning synthetic types of speech activities, built on algorithms, including various methods of working with texts of the network discourse, aimed at simultaneous formation of oral and written language skills, is the method “mobile video”. This model promotes the formation of communicative competence in the teaching of Russian to foreigners with the help of traditional and new methods and teaching methods, such as: mobile video, voice, comments in social networks, post publication, video subtitling, hyperlinks and etc. The proposed model of learning synthetic types of speech activity has been tested, the results of experimental training show that the application of the proposed model contributes to the formation of skills necessary for communication in a natural language environment, it also enables effective delivery of training activities using the potential of information and communication space.