Explosive Type Research Articles

The high-speed two-channel analyzer of optically dense aerosol emissions based on diode optocouplers with a wavelength of 0.65 and 3.4 microns

A two-channel analyzer of optically dense flammable aerosol fluxes based on two parallel diode optocouplers with a wavelength of electromagnetic radiation λ=0.65 and 3.4 μm, a speed of tau≤ 0.05 s and the transmission of digitized data to a server up to 1200 m away via the RS-485 interface has been developed. Its design and characteristics in the process of detecting particle streams with a diameter of 0.2 to 5000 μm with an optical density of D≤3.5 are described. It is shown that the values of the ratio of wave attenuation coefficients with λ=0.65 and 3.4 μm to the droplet size calculated on the basis of the theory of radiation scattering Mi are consistent with the experimental ones. The created aerosol analyzer can be used in the express analysis of technogenic airborne emissions of fuel liquids and for the development of large-scale generators of explosive type when creating pulse barriers from clouds of finely dispersed aerosol in the atmosphere. Keywords: aerosol analyzer, speed, diode optocouplers, infrared and visible radiation, attenuation factor, optically dense emissions, Mi scattering theory, fuel liquids.

Application Software Developed for the Determination of Expansion Volume in Clay Soil Generated by the Detonation of an Explosive Charge

Blasting in clay soil in the field of anchoring and foundation of objects and structures has its benefits in construction and geotechnical practice. The foundations of the method lay in the fact that a shock wave is generated when the explosive charge is detonated. The shock wave, with high pressure at the wavefront, causes the natural structure of the clay soil to be destroyed, and a spherical expansion in the clay mass is formed. The presented research is focused on determining the shape and volume of the resulting expansion in test blasts performed with several types of explosives. An application named Borehole was developed to determine the resulting spherical expansion formed after the detonation of an explosive charge with the integration of the GNSS method of measurement, depth camera, and laser. The application Borehole calculates expansion volume based on the coordinates obtained with the GNSS and the laser-obtained distance of the formed expansion and provides a graphical interpretation in 2D and 3D views. Additionally, when developing the application Borehole, compatibility with CAD tools was considered, primarily for better verification and a more detailed graphical interpretation of 3D views. The developed method allows for simple determination of the volume and dimension of the spherical expansion in clay soil with acceptable accuracy for the design and building of geotechnical structures constructed above and underground.

RANCANGAN GEOMETRI PELEDAKAN BATUAN GRANODIORIT PT. GILGAL BATU ALAM LESTARI MEMPAWAH KALIMANTAN BARAT

PT. Gilgal Batu Alam Lestari (PT. GILBAL) is a granodiorite mining company whose activities include stripping overburden, excavation/mining using the blasting method, transporting blasted materials and processing granodiorite in processing units. The blasting design parameters are influenced by the proper selection of the hole diameter and pitch height. The effect of burden, spacing, stemming, subdrilling, the depth of the shot holes is very important to anticipate the geological conditions and the type of explosives used. The purpose of this research is to study and calculate the size of rock fragmentation resulting from blasting and analyze the size distribution of fragmentation in blasting activities using the Kuz-Ram method and Split Desktop 4.0 software. The method of solving the problem in this research is to design a good blasting geometry to get the granodiotite fragmentation size < 50 cm. The proposed geometric design uses RL. Ash, CJ. Konya and ICI-Explosive. The results of the design RL. Ash obtained burden (B) 1.95 m, spacing (S) 2.34 m, steaming (T) 1.36 m, subdrilling (J) 0.585 m, blast hole depth (H) 5.85 m, ladder height ( L) 6 m, Powder column (PC) 4.49 m, hole diameter (De) 3 inches. CJ. Konya obtained B 2 m, S 2.375 m, T 1.4 m, J 0.6 m, H 5.69 m, L 6 m, PC 4.29 m, De 3 inches. According to the ICI-Explosive theory, B 1.9 m, S 1.9 m, T 1.52 m, J 0.608 m, H 6.08 m, L 6 m, PC 3.952 m, De 3 inches. The proposed design using ICI-Explosive and Kuz-ram found that the fragmentation size of 50 cm passed the 89.10% sieve and the cost of blasting was Rp. 115,237,500,-more likely to be implemented because it requires minimal blasting costs and fragmentation in accordance with the bucket capacity and company design compared to the RL. Ash method. and CJ. Konya. The distribution of fragmentation using Split Desktop obtained a fragmentation size of 50 cm which passed the sieve of 97.11%. It is necessary to conduct a more in-depth study related to the ideal blasting geometry from a technical and economic point of view as well as strict supervision of the blasting geometry design that has been designed to be implemented in the field.

Physical modeling of magma chamber of slamet volcano by means of satellite gravimetric data

Slamet Volcano (3,432 m) is the highest volcano in Central Java, Indonesia, with a weak explosive type of eruption compared to other active volcanoes. Designing the magma chamber model may help reveal the characteristics of Slamet Volcano. The modelling uses the gravimetric satellite data from GGMplus, which is best in spatial resolution compared to other satellite data, i.e. 220 m. Data processing begins with Bouguer correction and terrain correction and has resulted in complete Bouguer anomalies data, with values ranging from 11.068 – 117.451 mGal. Further, residual Bouguer anomalies data were obtained after data reduction to the horizontal surface and removal of regional anomalies data, to obtain values ranging from -67.569 – 38.808 mGal. The residual anomaly contour map shows the lowest anomalous value is under the volcanic cone at positions of 109.21967° E and 7.24281° S which is estimated to be the location of the magma chamber of Slamet Volcano. However, the inversion modeling resulting from the residual Bouguer anomalies data shows that the magma chamber of Slamet Volcano can be observed clearly at positions of 109.22053° E and 7.24719° S. The location of the magma chamber is not perfectly vertical under the volcanic cone but has a slight slope. The obtained model of the magma chamber has a relatively small volume and shallow depth, i.e. about 1 – 4 km. The obtained physical parameters of the magma chamber impact the characteristics of the eruption of Slamet Volcano which tend to be weak explosive.

Improvement of the current methodology for calculating the parameters of drilling and blasting on the explosive force

Purpose. Improvement of the current methodology for calculating the parameters of drilling and blasting (D&B) by determining the explosive force by the degree of realization of the detonation velocity for all types of industrial explosives (IE). The methodology of research. To solve the problem, a systematic approach was used, including an analysis of the current industry methodology for calculating the parameters of D&B in underground ore mining using IE, improvement of the power-law dependence of the calculation of the line of least resistance (LLR) of charges by determining the coefficient of explosive force of the IE, taking into account the degree of implementation of the burning rate, as well as approbation of the improved technique in the conditions of the operating iron ore mine. Findings. According to the methodology for determining the coefficient of explosive force of explosives (EX) according to the degree of implementation of the burning rate and according to the results of experimental studies of the change in the burning rate of the bulk emulsion explosive (EE) Ukrainit-PP-2, an improvement is proposed for the current industry methodology for calculating the parameters of D&B for the mines of the Kriviy Rig basin and the Private Joint Stock Society "Zaporozhye iron ore plant" (PJSS "ZIOP"). This made it possible, in the conditions of the experimental block of the mine "Yubileinaya" of the PJSS "Sukhaya Balka", using the bulk EE Ukrainit-PP-2, to increase the LLR and the distance between the borehole bottom up to 17%, and to obtain good results of ore reduction. The originality. The well-known power-law dependence of the determination of the LLR of borehole for rock breaking has been improved through the refinement of the coefficient of explosive force of the IE, which takes into account the degree of realization of the burning rate EX. Practical implications. The results of the research have improved the power-law dependence of the calculation of the LLR on the explosive force, taking into account the degree of implementation of the burning rate, the use of which will allow rationalizing the parameters of the D&B when breaking the ore mass using all types of IE.

Flame propagation characteristics of methane explosion under different venting conditions

Air mixed with methane commonly causes explosion accidents. Explosion vents can discharge the explosion pressure and release energy to reduce the explosion impact. Explosion vents are widely applied to gas transportation pipelines and other pressure equipment. To determine the influence of explosion vent areas and types on dynamic characteristics of methane flame propagation, in this study, an explosion pipe system was established to explore the effects of the 22.89-cm2 circular (1#), 15.20-cm2 circular (2#), 9.07-cm2 circular (3#), and 15.20-cm2 cross-shaped (4#) vents on flame propagation of methane explosion and to compare these effects with those of a closed pipe. The experimental results indicated that the explosion vent accelerated flame propagation velocity (v) and considerably reduced explosion pressure (P) and flame temperature (T) compared with the closed pipe results. v, T, and P reached maximum values at 10 vol% methane concentration. As the vent area increased, the v of the three circular vents increased. Flame propagation velocity in 1#, 2#, and 3# increased by 23.13 %, 21.57 %, and 4.55 % compared with that of the closed pipe (13.40 m/s), respectively. Compared with the closed pipe values of 0.973 MPa and 1678.13℃ for P and T, decreases of 10.30 %, 12.50 %, 38.00 %, and 1.82 %, 10.53 %, 11.22 % were observed in 1#, 2#, and 3#, respectively. Under equal explosion vent areas (15.20 cm2) but different vent types (2# circular and 4# cross), as the equivalent diameter of vents increased, P and T decreased by 12.50 %, 20.91 %, and 10.53 %, 10.01 %, and v increased by 21.57 % and 12.61 %.

TELS: Evolution patterns of research keywords from the evidence of PNAS Social Sciences topics.

By reviewing scientific literature, researchers may obtain a comprehensive understanding of field developments, keeping abreast of the current research status and hotspot shifts. The evolution pattern of keywords is supposed to be an efficient indicator in revealing the shifting and sustainability configuration of scientific concepts, ideas, and research hotspots. Here we take an extensive investigation of the evolution of keywords among all publications in PNAS Social Sciences from 1990 to 2021. Statistical tests show the keyword mention time series always accompanied by the emergence of a log-normal distribution. Additionally, we introduce a novel schema of four patterns (TELS), which are Transient impact type, Explosive impact type, Large impact type, and Small impact type, respectively, to illustrate the evolution of keywords. The TELS schema can be used to capture the whole life circle feature of any proposed keyword, from a pool of candidates. By dividing the entire time into four periods, we also introduce the concept of elite keywords to reveal the temporal feature of social sciences focus. An explicit transition from anthropology research to neuroscience and social problems research can be observed from the evolution diagram. We argue that the proposed method is of general sense and might be applicable to other fields of science.

Formation of Shaped Charge Projectile in Air and Water.

With the improvement of the antiknock performance of warships, shaped charge warheads have been focused on and widely used to design underwater weapons. In order to cause efficient damage to warships, it is of great significance to study the formation of shaped charge projectiles in air and water. This paper uses Euler governing equations to establish numerical models of shaped charges subjected to air and underwater explosions. The formation and the movement of Explosively Formed Projectiles (EFPs) in different media for three cases: air explosion and underwater explosions with and without air cavities are discussed. First, the velocity distributions of EFPs in the formation process are discussed. Then, the empirical coefficient of the maximum head velocity of EFPs in air is obtained by simulations of air explosions of shaped charges with different types of explosives. The obtained results agree well with the practical solution, which validates the numerical model. Further, this empirical coefficient in water is deduced. After that, the evolutions of the head velocity of EFPs in different media for the above three cases are further compared and analyzed. The fitting formulas of velocity attenuation of EFPs, which form and move in different media, are gained. The obtained results can provide a theoretical basis and numerical support for the design of underwater weapons.

Sizes of gas microbubbles sensitizing emulsion explosive along an upward borehole

When sensitizing emulsion explosives (EE) with gas microbubbles (GMB), the size of the latter has a significant effect on the detonation and susceptibility of EE to the initiating pulse. With a decrease in the total porosity of EE below a certain limit, it loses the ability of detonation decomposition, and with an increase above a certain limit, it loses the aggregate stability due to the fusion of GMB. At the same time, too small or too large GMBs do not form ‘hot spots’ that serve as ignition centers when initiating EE. When conducting blasting operations in monolithic rocks, both zones of increased and decreased density are formed in the upward borehole charges of EE under the influence of gravitational forces compared to the density of EE at atmospheric pressure. Therefore, in the lower part of the charge, due to the excessive hydrostatic pressure from the charge column, there is a decrease in the size of GMB and a decrease in the total porosity of the EE, while in the upper part there is an increase in the size of GMB and an increase in the total porosity of the EE. These circumstances serve as a source of failures during blasting of upward boreholes, therefore, the identification of patterns of changes in the size of GMB along the length of this charge is of great practical importance. The paper provides a theoretical assessment of the size of GMB sensitizing EE along the length of upward boreholes. It is shown that the range of changes in the size of GMB along the length of an upward EE charge can vary within the limits significantly exceeding the range of changes in the size of GMD in the downward charges. The porosity and radius of GMB in EE based on a heavier matrix emulsion decrease with an increasing distance from the bottomhole faster than in EE with a lighter matrix emulsion. When initiating upward borehole EE charges sensitized by GMB, it is advisable to have an upper location of the intermediate detonator due to the likely development of unstable detonation modes when initiating a charge from the wellhead side. The obtained patterns are of interest to specialists involved in both the use of EE and the improvement of this type of industrial explosives.

Fractal Analysis for Wave Propagation in Combustion–Explosion Fracturing Shale Reservoir

The in-situ combustion–explosion fracturing technology in shale reservoirs can promote continuous fracture expansion with a radial detonation wave first converging into a shock wave and then decaying into an elastic wave. The transformation scale of the shale reservoir is determined by the range of wave propagation during combustion–explosion. As wave propagation paths are usually tortuous and fractal, the previous integer wave models are not competent to describe the wave propagation and estimate the impact range of the combustion–explosion fracturing process. This study develops two fractional wave propagation models and seeks analytical solutions. Firstly, a novel fractional wave model of rotation angle is proposed to describe the process of detonation waves converting into shock waves in a bifurcated structure. The radial displacement gradient of the detonation wave is represented by the internal expansion and rotation deformation of the shale. Secondly, another fractional wave propagation model of radial displacement is proposed to show the process of a shock wave decaying into an elastic wave. Thirdly, the proposed models are analytically solved through the fractional variable separation method and variational iteration method, respectively. Analytical solutions for rotation angle and radial displacement with fractal time and space are obtained. Finally, the impacts of the branching parameter of the detonation wave converge bifurcation system, aggregation order of detonation compression wave, and different types of explosives on the rotation angle of the shock wave are investigated. The propagation mechanism of the primary wave (P-wave) with time and space is analyzed. The analytical solutions can well describe the wave propagation process in fractured shales. The proposed fractional wave propagation models can promote the research of wave propagation in the combustion–explosion fracturing process of shale reservoirs.

Experimental and numerical study of damage mechanism of steel box girders under external blast loads

Steel box girders are commonly utilized in bridge construction, particularly in continuous bridges and long span cable-stayed and suspension bridge. The bridges are vulnerable to blast loads induced by accidental explosions and terrorist attacks. Moreover, these types of explosions always occur above the bridge decks. Hence, the steel box girders subjected to blast loads were investigated in this study. A field blast experiment on a steel box girder was carried out. Furthermore, a finite element model (FEM) was developed and validated by the experimental results. And the FEM yielded the same results as the experiment. The damage mechanism of the experimental specimen was revealed by the numerical model. The results showed that the damage of the steel box girder concentrated on the top plate, and the experimental specimen can be simplified to the analysis of stiffened plate. Based on the validated finite element model, parametric analysis was performed. The maximum displacement responses of the top plate, the damage modes and mechanisms, and the energy dissipation mechanism were discussed. The blast load parameters and the transverse web thickness were all found to have significant influences on the displacement responses of the top plate. Three main damage modes were observed in the steel box girder subjected to blast loads. The transverse web thickness has a substantial impact on the damage modes. Moreover, the damage mechanisms of the damage modes were revealed. When considerable plastic damage occurs, most of the energy is absorbed by the top plate and transverse web components, according to an examination of the energy absorption mechanism. The strength of the blast loads and the transverse web thickness significantly influence the energy absorption ratio of the top plate and transverse web components. The types of damaged components should be reduced from the standpoint of repairability. Hence, through the analysis, it is advised to increase the transverse web thickness to improve the repairability of the steel box girder after explosions.

Numerical simulation of the effect of water-decoupling charge blasting on reservoir permeability enhancement

In the development of deep resources, blasting fracturing technology is one of the most effective means to improve the permeability of otherwise low-permeability reservoirs, while the pressure rise time of shock wave and the charge structure are the key factors affecting the blasting effect. Thus, this paper first deduces a formula for the pressure rise time, based on which, the blast-induced damage evolution is numerically simulated, and the numerical result is consistent with the existing studies, which verifies the feasibility of the formula. In addition, the influence of decoupling coefficients (K) of different types of explosives (i.e. TNT, emulsion, and ANFO explosives) on the damage range of reservoir blasting is studied. It is found that under the blasting of different types of explosives, the damage evolution law of the reservoir is different, and appropriate explosives should be selected in combination with rock stratum parameters in actual construction. Finally, the increase in permeability and the drainage effect of the reservoir after blasting are quantified by numerical simulations. It is demonstrated the average permeability increment of the reservoir under the action of TNT explosive is the largest, which is 3.08 (K = 4), while that under the action of emulsion explosive and ANFO explosive are 1.49 (K = 2) and 1.17 (K = 3) respectively; and the changes in reservoir permeability and drainage volume are coherent with the range of damage; the greater the range of damage, the greater the reservoir permeability and the greater the drainage efficiency.

The Algorithm and Computer Code for Predicting Detonation Wave Parameters of Aluminized Explosives

In this work, the algorithm and computer code, named DETO, used to calculate the detonation wave parameters (i.e., the velocity of detonation and the detonation pressure) of aluminized explosives, based on the chemical equilibrium theory of detonation products, the hydrodynamic theory of detonation process, and the Becker - Kistiakowsky - Wilson (BKW) equation of state. The aluminum (Al) content reacting with detonation products on the detonation wavefront can be changed according to the user's assumptions. Compared to experimental data for several aluminized explosive types, the results calculated by DETO have the same, even higher accuracy than those calculated by other computer codes previously published. Specifically, the mean absolute deviation from experimental data is about 2% for the velocity of detonation (VOD) and about 8% for the pressure on the detonation wavefront. In addition, the study also confirmed that about 50% of Al powders participate in the reaction on the detonation wavefront.

Investigation on influence factors about damage characteristics of ice sheet subjected to explosion loads: Underwater explosion and air contact explosion

Ice blasting efficiency is greatly influenced by many factors of explosives. This study aims to investigate the laws of the damage characteristics of the ice sheet influenced by explosive factors. Fully-coupled numerical models of underwater explosions for ice-breaking were established based on the experimental test, and the numerical results were in good agreement with the experimental results. The damage characteristics of ice sheets subjected to underwater and air contact explosion loads were thoroughly investigated by changing explosive types, explosive shapes, and the length to diameter ratios of cylinder charge. The results demonstrate that high-energy explosives, such as HMX and OCTOL explosives, can result in more serious damage to the ice sheets than the explosion of TNT, FEFO, PBX9010, and TETRYL explosives. A cylinder charge can be suggested to improve the efficiency of ice-breaking owing to its adjustable length to diameter ratios. The underwater explosion type is preferable to the air contact explosion for ice-breaking owing to the combined action of shock wave and bubble loads. The prediction formulas for the failure diameters of the ice sheets are proposed based on dimensional analysis, which provides a reference for ice-blasting engineering.

Association of Mesoscale Auroral Structures and Breakups With Energetic Particle Injections at Geosynchronous Orbit

Geomagnetic substorms are associated with characteristic energetic particle injection signatures at geosynchronous orbit that are often dispersionless in both electrons and ions near the magnetic local time sector of auroral onset locations and are dispersed farther away from this region. Although the precise mechanism responsible for the coherent injection signatures at geosynchronous orbit have been the topic on considerable ongoing debate for decades, recent work on bursty bulk flows (BBFs) in the tail have led to the hypothesis that they may be the result of multiple, overlapping flow bursts penetrating into the inner magnetosphere from more distant downtail reconnection sites. Since auroral streamers are thought to be ionospheric signatures of BBFs in the tail, they can be used as proxies for testing this hypothesis. Using high resolution auroral imagery from the POLAR/VIS instrument combined with multi-spacecraft observations of energetic particle injections at geosynchronous orbit, we examine the association of mesoscale auroral structures with particle injection signatures over many hours during the 9 November 1998 storm. We find that the explosive types of auroral activations, such as pseudo-breakups and substorm onset breakups, are associated with the more intense and well-defined dispersed injection signatures, while intervals of isolated streamer activity appear to be associated with smaller dispersed “injectionlet” signatures. Furthermore, intervals of sustained, intense, and late expansion phase/recovery phase streamer activity appear to be associated with sustained elevated dispersed particle fluxes. These results are consistent with the hypothesis that it is the overlapping effects of sustained, intense multiple flow bursts penetrating toward the Earth that result in classical substorm particle injection signatures at geosynchronous orbit. However, it is also suggested that torches/omega-band tongues are the prime fate of braking isolated flow bursts (streamers) rather than the development of breakups, bulges, and substorm current wedge formation. A statistical analysis is presented showing that 93% of the observed torches evolved from streamers, 93% of streamers arriving in the equatorward regions of the bulge led to torches, 10.5% of such streamers led to breakups (either pseudo-breakups or substorm onsets), and only 3.5% of such streamers led to substorm onsets.

Influence of different shaped charge parameters on jet penetration into metallic target

In this paper, Autodyn-2D hydrocode is used to investigate the influence of shaped charge parameters on penetration performance. Two different algorithms of Autodyn-2D hydrocode are used to predict the jet penetration depthsinto steel target; they are: i)jetting analyses algorithm, and ii) jet formation and penetration algorithm. To validate the predictions of the present work, Autodyn hydrocode is fed with the data of tested shaped charges with different liner thicknesses. The predicted penetration depths are compared with the corresponding experimental measurements; good agreement is generally obtained. Then, the shaped charge with liner thickness of 1.1mm, that gives the maximum jet penetration into steel target, is selected to study the influence of other different shaped charge parameters on its penetration performance. These parameters include form, material and thickness of liner, standoff distance and type of high explosive material. The influence of each studied parameter is evaluated by comparing the jet penetration performance with that of the selected shaped charge. Samples of the obtained predicted results showing the influence of each shaped charge parameter on jet formation and its penetration depth into steel target are presented and discussed. Four configurations are simulated into Autodyn-2D hydrocode considering the parameters that improve the penetration performance of the selected shaped charge. The obtained predictions result in the replacement of RDX by HMX explosive type and increasing the standoff distance from 29 to 40mm of the selected shaped charge will improve its penetration capability by 28.5%.

Injuries From Explosions: More Differences Than Similarities Between Various Types.

To compare injury patterns of different types of explosions. A retrospective study of 4508 patients hospitalized due to explosions recorded in the Israel National Trauma Registry between January 1997 and December 2018. The events were divided into 4 groups: terror-related, war-related, civilian intentional explosions, and civilian unintentional explosions. The groups were compared in terms of injuries sustained, utilization of hospital resources, and clinical outcomes. Civilian intentional and terror-related explosions were found to be similar in most aspects except for factors directly influencing mortality and a larger volume of severely injured body regions among terror-victims. Comparisons between other groups produced some parallels, albeit less consistent. Civilian intentional explosions and civilian unintentional explosions were different from each other in most aspects. The latter group also differed from others by its high volume of life-threatening burns and a higher proportion of children casualties. While consistent similarities between explosion casualties exist, especially between victims of intentional civilian and terror-related explosions, the general rule is that clinical experience with a type of explosion cannot be directly transferred to other types.

Long-term Evolution of a Supernova Remnant Hosting a Double Neutron Star Binary

An ultra-stripped supernova (USSN) is a type of core-collapse supernova explosion proposed to be a candidate formation site of a double neutron star (DNS) binary. We investigate the dynamical evolution of an ultra-stripped supernova remnant (USSNR), which should host a DNS at its center. By accounting for the mass-loss history of the progenitor binary using a model developed by a previous study, we construct the large-scale structure of the circumstellar medium (CSM) up to a radius ∼100 pc, and simulate the explosion and subsequent evolution of a USSN surrounded by such a CSM environment. We find that the CSM encompasses an extended region characterized by a hot plasma with a temperature ∼108 K located around the termination shock of the wind from the progenitor binary (∼10 pc), and the USSNR blast wave is drastically weakened while penetrating through this hot plasma. Radio continuum emission from a young USSNR is sufficiently bright to be detectable if it inhabits our galaxy but faint compared to the observed Galactic supernova remnants (SNRs), and thereafter declines in luminosity through adiabatic cooling. Within our parameter space, USSNRs typically exhibit a low radio luminosity and surface brightness compared to the known Galactic SNRs. Due to the small event rate of USSNe and their relatively short observable life span, we calculate that USSNRs account for only ∼0.1%–1% of the total SNR population. This is consistent with the fact that no SNR hosting a DNS binary has been discovered in the Milky Way so far.

On a High-Precision Method for Studying Attractors of Dynamical Systems and Systems of Explosive Type

The author of this article considers a numerical method that uses high-precision calculations to construct approximations to attractors of dynamical systems of chaotic type with a quadratic right-hand side, as well as to find the vertical asymptotes of solutions of systems of explosive type. A special case of such systems is the population explosion model. A theorem on the existence of asymptotes is proved. The extension of the numerical method for piecewise smooth systems is described using the Chua system as an example, as well as systems with hysteresis.

High Quantum Yield Nitrogen-Doped Carbon Quantum Dot-Based Fluorescent Probes for Selective Sensing of 2,4,6-Trinitrotoluene

Fluorescent carbon quantum dots hold great promise for the determination of nitro-explosive 2,4,6-trinitrotoluene (TNT), a potential environmental pollutant. Here, a nitrogen-doped carbon quantum dot (N-CQD)-based fluorometric probe with high quantum yield (73.10%) was developed for the selective determination of TNT. N-CQDs were synthesized by the reflux method using citric acid (CA) as a carbon precursor and ethylenediamine (EDA) with diaminocyclohexane (DACH) as nitrogen precursors. N-CQDs, with excitation and emission wavelengths of 360 and 460 nm, respectively, were highly selective toward TNT among different types of explosives [i.e., tetryl, 2,4,6-trinitrophenol (TNP), 2,4-dinitrotoluene (DNT), 4-amino-2,6-dinitrotoluene (ADNT), HMX, 1,3,5-trinitroperhydro-1,3,5-triazine (RDX), and pentaerythritol tetranitrate (PETN)]. As a result of the dominant FRET mechanism secondarily assisted by ground-state donor–acceptor complexation, the fluorescence of N-CQDs showed excellent quenching in the presence of TNT. The structure of N-CQDs was elucidated using X-ray photoelectron spectroscopy, X-ray diffraction, IR, Raman, high-resolution transmission electron microscopy, and dynamic light scattering techniques, and their interaction mechanism with TNT was resolved using the Gaussian (i.e., highest occupied molecular orbital–lowest unoccupied molecular orbital energy levels) program. The limit of detection and limit of quantification in aqueous media were 30.0 and 90.0 nM, respectively, while the Benesi–Hildebrand binding constant of N-CQDs was 2.22 × 103. In the presence of common soil ions, explosive mixtures, and camouflage materials, the N-CQDs could determine TNT with recoveries between 94.9 and 104.9%. In addition, sandy soil specimens were artificially contaminated with TNT as real samples, and the TNT extracted from these samples was determined by both N-CQDs and the reference liquid chromatography with tandem mass spectrometry method to validate the proposed fluorometric method. To design field detection techniques, two different support materials based on the thin layer chromatography-paper and hydrogel (N-CQD-gel) were developed, and TNT was determined visually at a μM level with both materials. The developed support materials make N-CQDs potentially useful in environmental sensor applications with their selective and sensitive sensing ability.