Time Of Explosion Research Articles

Isolation and characterization of a multidrug-resistant Staphylococcus aureus infecting phage and its therapeutic use in mice.

In recent years, the emergence of multidrug-resistant bacteria has limited the selection of drugs for treating bacterial infections, reduced clinical efficacy, and increased treatment costs and mortality. It is urgent to find alternative antibiotics. In order to explore a new method for controlling methicillin-resistant Staphylococcus aureus (S. aureus), this study isolated and purified a multidrug-resistant S. aureus broad-spectrum phage JPL-50 from wastewater. JPL-50 belongs to the Siphoviridae family after morphological observation, biological characterization, and transmission electron microscopy (TEM) fragmentation spectrum analysis. It can cleave 84% of tested S. aureus (168/200), in which 100% of tested mastitis-associated strains (48/48) and 72.04% of MRSA strains (67/93) were lysed. In addition, it has an optimal growth temperature of about 30°C, a high activity within a wide pH range (pH 3-10), and an optimal multiplicity of infection of 0.01. The one-step growth curve shows a latent time of 20 min, an explosive time of 80 min. JPL-50 was 16 927bp in length and was encoded by double-stranded DNA, with no genes associated with bacterial resistance or virulence factors detected. In a therapeutic study, injection of the phage JPL-50 once and for 7 times in 7 days protected 40% and 60% of the mice from fatal S. aureus infection, respectively. More importantly, JPL-50-doxycycline combination could effectively inhibit host S. aureus in vitro and reduce the use of doxycycline within 8 h. In conclusion, the bacteriophage JPL-50 has a wide lysis spectrum, high lysis rate, high tolerance to extreme environments, and moderate in vivo activity, providing ideas for developing multidrug-resistant S. aureus infections.

An Integrated Experimental and Modeling Approach for Assessing High-Temperature Decomposition Kinetics of Explosives.

We present a new integrated experimental and modeling effort that assesses the intrinsic sensitivity of energetic materials based on their reaction rates. The High Explosive Initiation Time (HEIT) experiment has been developed to provide a rapid assessment of the high-temperature reaction kinetics for the chemical decomposition of explosive materials. This effort is supported theoretically by quantum molecular dynamics (QMD) simulations that depict how different explosives can have vastly different adiabatic induction times at the same temperature. In this work, the ranking of explosive initiation properties between the HEIT experiment and QMD simulations is identical for six different energetic materials, even though they contain a variety of functional groups. We have also determined that the Arrhenius kinetics obtained by QMD simulations for homogeneous explosions connect remarkably well with those obtained from much longer duration one-dimensional time-to-explosion (ODTX) measurements. Kinetic Monte Carlo simulations have been developed to model the coupled heat transport and chemistry of the HEIT experiment to explicitly connect the experimental results with the Arrhenius rates for homogeneous explosions. These results confirm that ignition in the HEIT experiment is heterogeneous, where reactions start at the needle wall and propagate inward at a rate controlled by the thermal diffusivity and energy release. Overall, this work provides the first cohesive experimental and first-principles modeling effort to assess reaction kinetics of explosive chemical decomposition in the subshock regime and will be useful in predictive models needed for safety assessments.

Statistical analysis of the ground deformation of Vulcanian explosions at Sakurajima volcano, Japan

The forecast of pulsatory explosions during volcanic unrest periods is an essential issue for the assessment and mitigation of volcanic hazards. Although various precursors are detectable through geophysical and geochemical monitoring, difficulties remain in precisely constraining possible scenarios. A probabilistic approach is effective in assessing risk while considering various uncertainties. Sakurajima volcano characterized by frequent Vulcanian activity is one of the suitable fields for the probabilistic forecast of pulsatory explosions. Their inflation-deflation patterns of ground deformation related to Vulcanian explosions are useful for evaluating the imminence and size of the next event. The large database obtained from its vigorous activity can contribute to statistical analysis. In this study, aiming the probabilistic forecast of the timing and size of explosions, we investigated the duration of inflation and volume changes at the pressure source using strain records of over 5000 events of Sakurajima volcano. Then, a stochastic model was estimated to explain the distribution of these events. The log-logistic distribution was found to be an appropriate model for data distribution, indicating the presence of competing processes, such as pressurization and depressurization, in the conduit. The model parameters of the log-logistic distribution temporally fluctuated reflecting the volcanic activity, especially increasing the magma supply from a deep region. We also suggested a methodology to constrain the probabilities of the likely timing and size of an imminent explosion using real-time strain monitoring and an estimated model distribution. Although some improvements would be needed for practical forecasting, our approach could be useful in predicting possible ash hazards.

Physical Properties of Type II Supernovae Inferred from ZTF and ATLAS Photometric Data

We report an analysis of a sample of 186 spectroscopically confirmed Type II supernova (SN) light curves (LCs) obtained from a combination of Zwicky Transient Facility (ZTF) and Asteroid Terrestrial-impact Last Alert System observations. We implement a method to infer physical parameters from these LCs using hydrodynamic models that take into account the progenitor mass, the explosion energy, and the presence of circumstellar matter (CSM). The CSM is modeled via the mass-loss rate, wind acceleration at the surface of the progenitor star with a β velocity law, and the CSM radius. We also infer the time of explosion, attenuation (A V ), and the redshift for each SN. Our results favor low-mass progenitor stars (M ZAMS < 14 M ⊙) with a dense CSM ( Ṁ > 10−3 M ⊙ yr−1, CSM radius ∼ 1015 cm, and β > 2). Additionally, we find that the redshifts inferred from the SN LCs are significantly more accurate than those inferred using the host galaxy photometric redshift, suggesting that this method could be used to infer more accurate host galaxy redshifts from large samples of Type II SNe in the LSST era. Lastly, we compare our results with similar works from the literature.

Hypothesis testing with explosive time series. An approach to the theory of the functional central limit theorem

Hypothesis testing with explosive time series. An approach to the theory of the functional central limit theorem

SN 2020zbf: A fast-rising hydrogen-poor superluminous supernova with strong carbon lines

SN 2020zbf is a hydrogen-poor superluminous supernova (SLSN) at z = 0.1947 that shows conspicuous C II features at early times, in contrast to the majority of H-poor SLSNe. Its peak magnitude is Mg = −21.2 mag and its rise time (≲26.4 days from first light) places SN 2020zbf among the fastest rising type I SLSNe. We used spectra taken from ultraviolet (UV) to near-infrared wavelengths to identify spectral features. We paid particular attention to the C II lines as they present distinctive characteristics when compared to other events. We also analyzed UV and optical photometric data and modeled the light curves considering three different powering mechanisms: radioactive decay of 56Ni, magnetar spin-down, and circumstellar medium (CSM) interaction. The spectra of SN 2020zbf match the model spectra of a C-rich low-mass magnetar-powered supernova model well. This is consistent with our light curve modeling, which supports a magnetar-powered event with an ejecta mass Mej = 1.5 M⊙. However, we cannot discard the CSM-interaction model as it may also reproduce the observed features. The interaction with H-poor, carbon-oxygen CSM near peak light could explain the presence of C II emission lines. A short plateau in the light curve around 35–45 days after peak, in combination with the presence of an emission line at 6580 Å, can also be interpreted as being due to a late interaction with an extended H-rich CSM. Both the magnetar and CSM-interaction models of SN 2020zbf indicate that the progenitor mass at the time of explosion is between 2 and 5 M⊙. Modeling the spectral energy distribution of the host galaxy reveals a host mass of 108.7 M⊙, a star formation rate of 0.24−0.12+0.41 M⊙ yr−1, and a metallicity of ∼0.4 Z⊙.

Supernovae in 2023 (review): possible breakthroughs by late observations

I present a review of how late observations of supernovae, of the nebular phase, and much later of supernova remnants (SNRs), and their analysis in 2023 made progress towards possible breakthroughs in supporting the jittering jets explosion mechanism (JJEM) for core-collapse supernovae (CCSNe) and in introducing the group of lonely white dwarf (WD) scenarios for type Ia supernovae (SNe Ia). The new analyses of CCSN remnants (CCSNRs) reveal point-symmetric morphologies in a way unnoticed before in several CCSNRs. Qualitative comparison to multipolar planetary nebulae that are shaped by jets suggests that jets exploded these CCSNe, as predicted by the JJEM, but incompatible with the prediction of the delayed neutrino explosion mechanism. The spherical morphology of the ejecta Pa 30 of the historical type Iax supernova (SN Iax) of 1181 AD, which studies in 2023 revealed, is mostly compatible with the explosion of a lonely WD. Namely, at the explosion time, there is only a WD, without any close companion, although the WD was formed via a close binary interaction, i.e., binary merger. Identifying point-symmetry in SNR G1.9+0.3, a normal SN Ia and the youngest SN in the Galaxy, suggests an SN explosion of a lonely WD inside a planetary nebula (an SNIP). The group of lonely WD scenarios includes the core degenerate scenario and the double degenerate scenario with a merger to explosion delay (MED) time. SN Ia explosions of lonely WDs are common and might actually account for most (or even all) normal SNe Ia.

SN 2015da: late-time observations of a persistent superluminous Type IIn supernova with post-shock dust formation

ABSTRACT We present photometry and spectroscopy of the slowly evolving superluminous Type IIn supernova (SN) 2015da. SN 2015da is extraordinary for its very high peak luminosity, and also for sustaining a high luminosity for several years. Even at 8 yr after explosion, SN 2015da remains as luminous as the peak of a normal SN II-P. The total radiated energy integrated over this time period (with no bolometric correction) is at least $1.6 \times 10^{51}$ erg (or 1.6 FOE). Including a mild bolometric correction, adding kinetic energy of the expanding cold dense shell of swept-up circumstellar material (CSM), and accounting for asymmetry, the total explosion kinetic energy was likely 5–10 FOE. Powering the light curve with CSM interaction requires an energetic explosion and 20 M$_{\odot }$ of H-rich CSM, which in turn implies a massive progenitor system $\gt $30 M$_{\odot }$. Narrow P Cyg features show steady CSM expansion at 90 km s$^{-1}$, requiring a high average mass-loss rate of $\sim$0.1 M$_{\odot }$ yr$^{-1}$ sustained for two centuries before explosion (although ramping up toward explosion time). No current theoretical model for single-star pre-SN mass-loss can account for this. The slow CSM, combined with broad wings of H $\alpha$ indicating H-rich material in the unshocked ejecta, disfavours a pulsational pair instability model for the pre-SN mass-loss. Instead, violent pre-SN binary interaction is a likely culprit. Finally, SN 2015da exhibits the characteristic asymmetric blueshift in its emission lines from shortly after peak until the present epoch, adding another well-studied superluminous SNe IIn with unambiguous evidence of post-shock dust formation.

A belief rule-based classification system using fuzzy unordered rule induction algorithm

A rule-based system is a widely used artificial intelligence system that employs a set of rules to make decisions. The belief rule-based (BRB) classification system is an extension of fuzzy rule-based (FRB) system that handles uncertainty and imprecision in classification tasks by incorporating Dempster-Shafer evidence theory and fuzzy set theory. However, the BRB classification system suffers from the combinatorial explosion and high time complexity problems. To solve these issues, the fuzzy unordered rule induction algorithm (FURIA) is introduced into the BRB classification systems to design a novel BRB classification system in this paper. FURIA is computationally less complex and has superior classification performance. The proposed system outperforms BRB classification systems in terms of classification performance and significantly reduces the number of rules and conditions. Furthermore, the proposed system offers a more effective solution than FURIA. To evaluate the validity and superiority of the proposed system, we conduct two classification experiments, comparing it with five traditional classifiers and seven rule-based systems, respectively, in terms of classification performance and interpretability.

Lower and upper bounds for the explosion times of a system of semilinear SPDEs

In this paper, we obtain lower and upper bounds for the blow-up times for a system of semilinear stochastic partial differential equations. Under suitable assumptions, lower and upper bounds of the explosive times are obtained by using explicit solutions of an associated system of random partial differential equations and a formula due to Yor. We provide lower and upper bounds for the probability of finite-time blow-up solution as well. The above obtained results are also extended for semilinear SPDEs forced by two-dimensional Brownian motions.

An interpolation inequality involving LlogL$L\log L$ spaces and application to the characterization of blow‐up behavior in a two‐dimensional Keller–Segel–Navier–Stokes system

AbstractIn a smoothly bounded two‐dimensional domain and for a given nondecreasing positive unbounded , for each and the inequality is shown to hold for any positive fulfilling This is thereafter applied to nonglobal solutions of the Keller–Segel system coupled to the incompressible Navier–Stokes equations through transport and buoyancy, and it is seen that in any such blow‐up event the corresponding population density cannot remain uniformly integrable over near its explosion time.

The specific current action integral for conductors exploded by high-frequency currents

The explosive emission processes that occur at electrode surface microprotrusions may have harmful effects in a variety of electrodynamic and acceleration systems exposed to high-power radio frequency electromagnetic waves. This paper presents the results of a radiative magnetohydrodynamic simulation of the explosion of copper conductors that occur under conditions inherent in the explosion of electrode microprotrusions, i.e., at current densities of the order of 109 A/cm2. Explosions occurring under quasi-stationary and radio frequency conditions (hereinafter referred to as quasi-stationary and radio frequency explosions, respectively) were considered. It was shown that in all the considered cases, the explosion occurred at high temperatures, so that the energy deposited in the conductor by the time of explosion exceeded the sublimation energy of the conductor material. It turned out, however, that the energy deposited in the conductor under radio frequency conditions, regardless of the frequency of current oscillations, was more than two times less than that deposited under quasi-stationary conditions. The explosion time was also virtually independent of the frequency, and it was approximately three times longer than that calculated for quasi-stationary conditions. For a radio frequency explosion, the specific current action integral was somewhat less (by about 25%) than that for a quasi-stationary explosion, and its value was actually independent of frequency. At the same time, in the radio frequency regime, the radiation power coming out of the conductor substance drops strongly, and it is almost two orders of magnitude smaller compared to the radiation power in the quasistationary regime.

The HST Nondetection of SN Ia 2011fe 11.5 yr after Explosion Further Restricts Single-degenerate Progenitor Systems

We present deep Hubble Space Telescope imaging of the nearby Type Ia supernova (SN Ia) 2011fe obtained 11.5 yr after explosion. No emission is detected at the SN location to a 1σ (3σ) limit of F555W > 30.2 (29.0) mag, or equivalently M V > 1.2 (−0.1) mag, neglecting the distance uncertainty to M101. We constrain the presence of donor stars impacted by the SN ejecta with the strictest limits thus far on compact (i.e., logg≳4 ) companions. H-rich zero-age main-sequence companions with masses ≥2 M ⊙ are excluded, a significant improvement upon the preexplosion imaging limit of ≈5 M ⊙. Main-sequence He stars with masses ≥1.0 M ⊙ and subgiant He stars with masses ≤0.8 M ⊙ are also disfavored by our late-time imaging. Synthesizing our limits on postimpact donors with previous constraints from preexplosion imaging, early-time radio and X-ray observations, and nebular-phase spectroscopy, essentially all formation channels for SN 2011fe invoking a nondegenerate donor star at the time of explosion are unlikely.

Experimental study on the explosion characteristics of ammonia-hydrogen-air mixtures

Ammonia-hydrogen blended fuel has drawn substantial attention as an environmentally friendly, carbon-free fuel because it effectively overcomes the inherent disadvantages of pure ammonia in combustion performance, such as a high ignition energy, slow combustion rate, and low combustion efficiency. While recent research on the combustion performance of hydrogen-ammonia blends has advanced, there remains a scarcity of studies addressing the explosion characteristics of these fuels. In this paper, a series of experiments conducted within a standard 20-L spherical combustion chamber to investigate the explosion characteristics of ammonia-hydrogen-air premixed gases under diverse conditions, spanning from low to high pressures (0.02–0.3 MPa) and from fuel-lean to fuel-rich scenarios (0.7–1.5), are discussed. The results reveal that the explosion characteristics are pronouncedly enhanced by hydrogen addition. The maximum explosion pressure (Pmax) and maximum pressure rise rate ((dP/dt)max) increase, while the explosion time (texp) decreases with increasing hydrogen concentration. Pmax and (dP/dt)max exhibit linear increases as the initial pressure rises and reach their peaks at an equivalence ratio of 1.1; texp displays nonmonotonic variations with increasing initial pressure and equivalence ratio. Hydrogen addition remarkably increases the hydrodynamic instability and thermal-diffusion instability of the reactive mixture, enhances the thermal-mass diffusion on the flame front, and promotes flame deformation and cellular structure formation, resulting in an improvement of the flame propagation and compression effect on the unburnt reactant before the flame. Research into the explosion characteristics provides valuable insights for the safe storage and transportation of ammonia-hydrogen blended fuels. These results indicate avenues for further enhancing the detonation characteristics and explosion performance of ammonia-hydrogen blended fuels.

Анализ локальной сейсмичности западной части полуострова Таймыр по данным сейсмической станции «Колба»

In recent years, active development of coal deposits and works related to the creation of appropriate infrastructure (ports, roads, etc.) have been carried out in the western part of the Taimyr peninsula. The main objects are the port Buhta Sever (oil loading terminal), the Syradasay coal deposit and the port Yenisei. Work is also underway in the Lembersk coal mine and the associated port Dixon. The single seismic station “KOLBA” of the Arkhangelsk seismic network installed in October 2020 near Dixson regularly registers local seismic events, the natural nature of which is questioned. From October 2020 to February 2023, 150 seismic events with a magnitude range of ML from 0.4 to 2.4 were registered at distances up to 200 km from the seismic station. The purpose of our research is to give a reasonable answer on the basis of selected criteria about the nature of registered local events: earthquakes or man-made events. Cleaning seismic catalogs from man-made events has always been an urgent task, especially after the installation of each new seismic station in a little-studied area of the Arctic. The difficulty in determining the event nature lies in the absence of a regional hodograph and any reference data such as samples of waveforms, reliable information about the place, time and methods of industrial explosions, the absence of these events on the records of other seismic stations. In this regard, we have defined a set of criteria for determining the nature of events, which are reduced to the consideration of indirect signs. These are the location of an event near an industrial facility, the analysis of spectral-time diagrams and waveforms of seismic events, the analysis of the amplitudes ratio of volume and / waves, the daily distribution of seismic events and the magnitude range of recorded events. Despite the fact that individually each criteria is not a direct proof of the man-made events nature, their totality can be taken as a decision to exclude the event from the seismic catalog. In the process of determining the epicenters of events, we identified several groups related to various industrial facilities. The daily distribution diagram shows that local seismic events were recorded in the daytime with peak values at 13–14 hours and at 19–20 hours, which indicates the technogenic nature of events. The / ratio is &lt; 3.0 for all events, which most likely also indicates a technogenic nature, as with the presence of “bands” in the high frequency range on the spectral-time diagrams. The developed set of criteria for the identification of technogenic events allowed us to clean up the seismic catalog and attribute all 150 events to the manifestation of technogenic seismicity. The most effective criteria are the analysis of spectral-time diagrams, the / ratio and the daily distribution of events. In some cases, by the waveform types, it is also possible to determine whether an event belongs to a certain industrial facility (in particular, to the port of Buhta Sever).

The deflagration suppression effect of ammonium salt-modified dry water on methane-air mixtures: An experimental investigation

To evaluate the efficacy of ammonium salt-modified dry water in suppressing the deflagration of methane, in this study, four kinds of ammonium salts were chosen to modify the properties of dry water powders. The physical features of the modified dry water were tested and analyzed. Their suppression characteristics on methane explosion were experimentally explored, and the corresponding deflagration parameters were obtained. Results show that the Pmax and the (dP/dt)max first diminish and then increase with increasing amounts of modified dry water. The effect of ammonium dihydrogen phosphate-modified dry water (MAP-DW) on the explosion pressure is superior to that of other kinds. The delay effect of MAP-DW and ammonium polyphosphate-modified dry water (APP-DW) on explosion time is better for methane at equivalence ratios of 0.8 and 1.2. Moreover, the explosion suppression mechanism of the modified dry waters was proposed. The findings of this work are helpful for optimizing gaseous deflagration suppressants.

Solar energetic particles propagation during solar events at the beginning of the 25th solar cycle

Space weather is induced by solar events like solar flares, solar wind, the solar cycle, and coronal mass ejections. These solar events have the potential to affect various aspects of Earth, including radio communications, electric power failures, and navigation signals, and pose risks to spacecraft and astronauts. Solar activity is more or less intense according to the solar cycle. We are currently in the 25th solar cycle, which began in 2019. This research studies the space weather at the beginning of the 25th solar cycle using the distribution data obtained from spacecraft including the explosion on the Sun’s surface, by analyzing the solar energetic particles (SEPs) propagation. The distribution of SEPs with flux; F is given by a power law for solar events on November 29, 2020, July 3, 2021, and April 22, 2022, with indices 6.2, 4.5, and 1.8 depending on energy. The propagation of the SEPs was studied using Ruffolo’s transport equation, which was solved using the Finite-differences method. We found that solar flares with higher X-ray intensity have a longer movement along the irregular magnetic field and arrive at Earth more quickly than those with lower X-ray intensity. The SEPs are weaker and have no impact on Earth, although both events generated coronal mass ejection. The M-class and X-class solar flares occurred during the beginning of the 25th solar cycle, the position of explosion and injection time of particles resulted in space weather with little impact on Earth.

Research the explosive train detonation time of the electronic time fuze for the underwater pressure device

In this paper, using numerical simulation combined with experiment, the detonation time of the explosive train of the electronic time fuze from the signal source to the fuze booster has been determined. The results show that the influence of the transmission line and the connector on the detonation train time is very small, this influence in the design can be ignored. The results after the study are proven experimentally and the experimental results show that the simulation results are reliable and highly applicable. The results of the article are applied to manufacturing and testing electronic time fuze use for the underwater pressure device.

Experimental and Numerical Studies on the Explosion Characteristics of Ethanol–Air Mixtures under Aviation Conditions

As a representative renewable biofuel, ethanol can reduce mankind’s dependence on petroleum resources and the emission of greenhouse gases and other pollutants. In recent years, the application of ethanol in the aviation field has begun to be a concern of scholars. As ethanol is a flammable liquid, it is significant to study its explosion characteristics in aviation conditions from a safety perspective. In this work, at 20 kPa, the explosion characteristics of ethanol–air mixtures (concentration 6~12%) were experimentally and numerically studied under an initial temperature range of 303 K~363 K. The effects of the initial temperature and concentration on the maximum explosion pressure, maximum rate of pressure rise, explosion time, and fast burning time were analyzed. In addition, the heat loss fraction and sensitivity analysis were examined and discussed. The main conclusions are as follows: A linear relationship exists between the maximum explosion pressure and the reciprocal of the initial temperature. The maximum rate of a pressure rise appears to decrease or at least approach a constant value as the initial temperature increases. The explosion time is significantly dependent on the concentration. At a constant concentration, the proportions of heat loss are approximately constant except for 12%. In our sensitivity analysis, R1 (H + O2 &lt;=&gt; O + OH) was the dominant elementary reaction.

Using spectral modeling to break light-curve degeneracies of type II supernovae interacting with circumstellar material

A large fraction of red-supergiant stars seem to be enshrouded by circumstellar material (CSM) at the time of explosion. Relative to explosions in a vacuum, this CSM causes both a luminosity boost at early times as well as the presence of symmetric emission lines with a narrow core and electron-scattering wings typical of type IIn supernovae (SNe). For this study, we performed radiation-hydrodynamics and radiative transfer calculations for a variety of CSM configurations (i.e., compact, extended, and detached) and documented the resulting ejecta and radiation properties. We find that models with a dense, compact, and massive CSM on the order of 0.5 M⊙ can match the early luminosity boost of type II-P SNe but fail to produce type IIn-like spectral signatures (also known as “flash features”). These only arise if the photon mean free path in the CSM is large enough (i.e., if the density is low enough) to allow for a radiative precursor through a long-lived (i.e., a day to a week), radially extended unshocked optically thick CSM. The greater radiative losses and kinetic-energy extraction in this case boost the luminosity even for modest CSM masses – this boost comes with a delay for a detached CSM. The inadequate assumption of high CSM density, in which the shock travels essentially adiabatically, overestimates the CSM mass and associated mass-loss rate. Our simulations also indicate that type IIn-like spectral signatures last as long as there is optically-thick unshocked CSM. Constraining the CSM structure therefore requires a combination of light curves and spectra, rather than photometry alone. We emphasize that for a given total energy, the radiation excess fostered by the presence of CSM comes at the expense of kinetic energy, as evidenced by the disappearance of the fastest ejecta material and the accumulation of mass in a dense shell. Both effects can be constrained from spectra well after the interaction phase.