Large-scale Blast Research Articles

Campylobacter fetus subspecies specific PCR assays inferred from comparative genomic analysis for accurate subspecies identification

Bovine Genital Campylobacteriosis (BGC) is caused by Campylobacter fetus subsp. venerealis and is a notifiable disease to the WOAH (World Organisation for Animal Health). For an effective BGC control program, the reliable differentiation of Campylobacter fetus subsp. venerealis (Cfv) from the closely related Campylobacter fetus subsp. fetus (Cff) is required. However, the available molecular C. fetus subspecies identification assays lack sensitivity and specificity to differentiate C. fetus isolates based on their phenotypic or genotypic differences. Furthermore, the current biochemical subspecies identification is not fully congruent with the genomic differentiation of C. fetus strains.In this study, the genome sequences of 41C. fetus strains with well identified subspecies, were analyzed with the large-scale BLAST score ratio (LS-BSR) pipeline to identify Cff and Cfv specific sequences. With this analysis, the asd gene encoding an aspartate-semialdehyde dehydrogenase was identified, which contained a 6-bp Cff-specific sequence, and this 6-bp sequence was absent in the asd gene of Cfv strains. This sequence was used for the development of PCR assays to differentiate Cff and Cfv strains. The C. fetus subspecies identification of the developed asd PCR assays was in full congruence with the genomic classification of strains and are recommended for molecular identification of C. fetus subspecies in BGC control programs.The asd PCR can be assessed on sequenced genomes using a web interface containing the Cfvcatch tool, which includes placement of the tested genome in a phylogenetic tree with reference C. fetus genomes to distinguish the two subspecies and to detect antimicrobial resistance genes.

Characterization of an Advanced Blast Simulator for Investigation of Large Scale Blast Traumatic Brain Injury Studies.

Blast traumatic brain injury (bTBI) is a prominent military health concern. The pervasiveness and long-term impacts of this injury highlight the need for investigation of the physiological outcomes of bTBI. Preclinical models allow for the evaluation of behavioral and neuropathological sequelae associated with bTBI. Studies have implemented rodent models to investigate bTBI due to the relative small size and low cost; however, a large animal model with similar neuroanatomical structure to humans is essential for clinical translation. Small blast simulators are used to induce bTBI in rodents, but a large animal model demands a larger device. This study describes a large advanced blast simulator (ABS4) that is a gas-detonation-driven system consisting of 5 sections totaling 40ft in length with a cross-section of 4 × 4 ft at the test section. It is highly suitable for large animals and human surrogate investigations. This work characterized the ABS4 in preparation of large-scale bTBI testing. An array of tests were conducted with target overpressures in the test section ranging from 10 to 50 psi, and the pressure-time profiles clearly illustrate the essential characteristics of a free-field blast wave, specifically a sharp peak pressure and a defined negative phase. Multiple blast tests conducted at the same target pressure produced very similar pressure profiles, exhibiting the reproducibility of the ABS4 system. With its extensive range of pressures and substantial size, the ABS4 will permit military-relevant translational blast testing.

The method of reducing energy consumption in large blast furnace smelting by low-silicon smelting

Currently, achieving carbon peaking and neutrality poses significant challenges for China's iron and steel industry. Low-carbon smelting in large blast furnaces (BFs) is poised to be a pivotal element in attaining the “double carbon” goal. This study, grounded in the fundamental process theory of blast furnace ironmaking, employs data analysis to investigate production technology across 25 large blast furnaces in China exceeding 4000 m3 in 2021. It specifically examines the correlation between pig iron silicon content and fuel consumption, elucidating strategies and techniques for low-silicon smelting. By exemplifying the reduction of silicon content in a 5050 m3 blast furnace of a Chinese enterprise, the study systematically delineates the low-silicon smelting process, including specific parameters and standards concerning fuel consumption, raw material conditions, and operational systems. The findings demonstrate that a reduction of 0.1% in pig iron silicon content can decrease carbonaceous fuel consumption by at least 5 kg/t. Given current raw material conditions and equipment levels, it is feasible to reduce the silicon content of iron in large-scale blast furnaces exceeding 4000 m3 in China to 0.3%.

Features of rock mass geodynamics during large-scale blasting in rockburst-hazardous iron ore mining

Features of rock mass geodynamics during large-scale blasting in rockburst-hazardous iron ore mining

Dynamic Response Mechanism of Thin-Walled Plate under Confined and Unconfined Blast Loads

Thin-walled metal plates and cabin structures are widely found in ships and cargos which are susceptible to attacks or accidental explosions. The present work focuses on the dynamic response mechanism of steel plates under unconfined and confined blast loads. In the experiment, digital image correlation (DIC) technique was applied to record and analyze the dynamic response process of a large-scale field blast test. The DIC measured curve and the numerically calculated curves agree well in both trends and peak values. Then, the dynamic response mechanisms of steel plates under an unconfined blast (UB) load and confined blast (CB) load were compared and discussed. The results show that the dynamic response of plates can be divided into three phases under both UB and CB loads, with different mechanisms. In phase I, plastic hinges start from the center and move to the boundary in the UB condition, while in the case of CB, plastic hinges occur close to the boundary and move in the opposite direction. In phase II, two plastic hinge lines propagate towards each other, a platform exists between the boundary, and the central area remains undeformed in the UB condition, while in the CB condition, larger deformation occurs in the peripheral region rather than the central area.

“In situ” studies on cokes drilled from tuyere to deadman in a large-scale working blast furnace

The properties and deterioration of coke have a significant impact on the thermal efficiency, fuel consumption, and CO2 emissions of blast furnace. Coke sample drilling is one of the effective ways to investigate coke behaviors in a working blast furnace. However, previous coke sample drilling process involved compressed coke, which cannot accurately reflect the actual condition of coke in blast furnace. Therefore, “in situ” coke samples were drilled for three times from tuyere to deadman in their original positions within a large-scale working blast furnace in the present work. The results show that the coke particle size degradation reaches 85.36 % in the 0–5 m zone at the tuyere level. The proportion of coke size less than 3 mm increases sharply along the tuyere direction, and a new method of calculating the depth of the tuyere raceway zone is proposed for the first time. The study based on the grey relational analysis shows that the depth of the raceway is closely related to the blast volume and the blast kinetic energy. Main factors causing the degradation of coke in the tuyere level are fully revealed in different regions. It is suggested to reduce CaO and alkali metals brought in blast furnace in order to protect coke.

Developments and Challenges in High-Performance Operation Control of Large-Scale Blast Furnace

Developments and Challenges in High-Performance Operation Control of Large-Scale Blast Furnace

Improved operation of a large-scale blast furnace using a hybrid dynamic model based optimizing control scheme

In the steel industry, the blast furnace (BF) is a core piece of equipment along the route from iron ore to steel, with the largest energy consumption and CO2 emissions. The stable, efficient, and economically viable thermal control of blast furnaces is still a challenging task, and fully automatic solutions are not applied industrially. The process exhibits multi-phase and multi-scale physio-chemical phenomena, in the presence of fast and very slow dynamics with latency periods of 6-8 h. Direct online measurements of key inner variables are missing, and unknown disturbances are strongly influencing the process; in particular, the quality of solid raw materials that are fed at the top of the furnace. Partial automation is the state-of-the-art strategy in the operation and control of industrial blast furnaces, and the experience and the dedication of the operators have a direct impact on the stability and efficiency of the operation. Model-based optimizing control schemes, which can be deployed either in closed-loop or as a guidance system to achieve a smooth, efficient, and reliable operation of blast furnaces, are promising. In this work, we propose a hybrid dynamic model based optimizing control scheme for the stable, energetically efficient, and economically optimal thermal control of blast furnaces. The underlying optimization problem is formulated as a combined tracking and performance optimizing control problem, where the goal is the tight control of the hot metal silicon content ([Si]) and the slag basicity (SB), while simultaneously maximizing the CO-efficiency of the furnace. These two variables are key product quality indices, and [Si] is an indicator of the internal thermal state of the BF process. Simulation results using real operational data of a large-scale industrial blast furnace are presented to demonstrate the potential of the approach for an improved operation of blast furnaces.

Synthesis mechanism of AlN–SiC solid solution reinforced Al2O3 composite by two-step nitriding of Al–Si3N4–Al2O3 compact at 1500 °C

The in-situ controllable synthesis of AlN–SiC solid solution reinforcement in large-sized Al–Si3N4–Al2O3 composite refractory by two-steps nitriding sintering was examined. In the first step, a dynamic Al@AlN structure was constructed in the composite by pre-nitriding at 580 °C. During the subsequent sintering process, it cracked above ∼900 °C, and micronized Al cluster (mixture of droplets and vapor) was extracted out gradually. As a result, multiple AlN mesophases were formed through different reaction paths, including i) initial AlN shell formed by solid Al with N2, ii) reaction of Al cluster with N2, and iii) reaction of Al cluster with Si3N4 from 900 °C to 1500 °C. The Si3N4 precursor serves as both a solid nitrogen source and an active Si source, and the controllable reaction between Al and Si3N4 leading to uniformly distributed AlN and Si mesophases. AlN–SiC solid solution is significantly formed when liquid Si appears. The shell, granule and whisker SiC–AlN solid solution were observed mainly depending on the dynamic AlN mesophase. The SiC–AlN solid solution reinforced Al2O3 materials is a novel promising refractory for large-scale blast furnace lining.

New design for control cage to enhance coverage and uniformity of shot blasting and its validation using DEM and experiment

Unlike shot peening, shot blasting is a process that primarily uses shot balls to remove foreign substances from metal surfaces. Shot blasting is classified into air-blowing and impeller-impact types. The latter is widely used in commercial large-scale shot blasting. This study proposes a new control cage with a concave or convex shape to improve coverage and uniformity in the impeller-impact type shot blaster. The effectiveness of the proposed control cage is verified using discrete element methods and experiments. Moreover, the optimal design in terms of mass flow, coverage, and uniformity is confirmed. Additionally, the distribution of marks on the surface is analyzed through experiments and simulations. Further, the shot ball is projected over a wider area on the surface when the new concave and convex model is employed at the control cage. Consequently, we confirm that the control cage with a concave shape forms approximately a 5-% higher coverage than the conventional model and uniform shot marks while using a low mass flow rate.

Piston mechanism of interaction of non-linear geomechanical and physicochemical gas exchange and mass transfer processes in coal-bearing rocks

The article focuses on a theoretical and experimental framework for the quantification of interaction between nonlinear geomechnical and physicochemical processes in high-stress coal-bearing rock mass during mining under high seismic risk due to large-scale blasting and earthquakes, as well as because of structural and temperature effects. The tests were aimed to examine and study comprehensively the piston mechanism of gas exchange and mass transfer processes, revealed recently at the Institute of Mining, SB RAS, as well as to explain the fact that the earthquake-induced low-velocity (quasi-meter range) pendulum waves (velocity to 1 ​m/s and frequency of 0.5–5 ​Hz) could stimulate an increase in the gas content in coal mines. In order to perform laboratory investigation at the Institute of Mining SB RAS, special-purpose stand for analyzing gas exchange and mass transfer processes in coal-bearing geomaterials under various thermodynamic conditions (P, V, T) and gas composition was constructed in cooperation with the Institute of Semiconductors Physics SB RAS. Matching of air flow rate with compression pressures allowed to obtain relations showing that air flow rate increases at the uncertain time interval under the increasing of the compression pressure. The same measurements was carried out with another gases such as Hydrogen H2, Helium He, methane CH4, carbon dioxide CO2 and carbon oxide CO. The laboratory tests aimed to detailed investigation of the previously revealed “piston mechanism” of gas exchange and mass transfer processes in the coal specimens and their quantitative description in terms of theory of the pendulum waves were carried in the first time. Consequently, there are some arguments for the testing of the opportunity of quantitative description of the “piston mechanism” related to gas exchange and mass transfer processes in the scale of coal mines. It is relevant when pendulum waves induced by powerful earthquakes and technical blasting reaches the mine.

Reduction of respirable dust-induced impact on open pit mine personnel in large-scale blasting

Reduction of respirable dust-induced impact on open pit mine personnel in large-scale blasting

Seismically safe parameters of confined blasting in levelling dry dock bottom

During construction of a dry dock, it became necessary to level the bottom of gneissic granite rock mass to 7 m by blasting. The blasting site appeared to be spaced at 8.5–20.0 m from a reinforced concrete caisson and a sand cofferdam reinforced with soil–cement piles. Aiming to ensure the required levelling at 16.2 m, the preset fragmentation quality and the reduced seismic safety, the parameters associate with the drilling-and-blasting pattern were calculated. The values of PPV caused by blasting-induced seismic waves in the caisson and cofferdam were found from the constructed formulas. The experimental measurement of ground vibrations induced by blasting used seismic recorder Vibracord DX. Al in all, 20 large-scale blasts were performed, and the blasted rock volume totaled 9 Km3. The comparison of the actual and calculated values of PPV in the caisson and cofferdam proves reliability of the presented formulas. It is calculated that PPV caused by the blasting-induced seismic waves at the farther wall of the caisson and at the nearest wall of the soil–cement piles are 2.0–27.0 mm/s and 2.0–22.0 mm/s, respectively, which is much less than the allowable PPV of 100–500 mm/s for the hydraulic engineering structures. It has been determined during blasting that the caisson preserves its integrity and no increase in the water inflow from the gulf is observed.

Обоснование эффективности взрывных работ с использованием электронных систем в сравнении с неэлектрическими средствами инициирования

Carrying out large-scale blasting using non-electric primers in surface mining is concerned with a number of deficiencies, one of which being the error in borehole and surface delay times. As a consequence, the design blasting system is compromised, the face blasting rates are affected, and the rock mass fragmentation quality goes down. Due to their advantage in the triggering accuracy, the electronic blasting systems ensure absolute control over the execution of large-scale blasting, reduce the negative impact of blasting operations on residential areas near the surface mine and improve the quality of rock mass fragmentation. Electronic blasting systems enable the development of new ways to execute blasting, for example, though selecting the face blasting rates, which in turn increases the rock mass fragmentation quality and reduces dilution. The paper presents comparative indicators of bias in the nominal delay times of various non-electric primers and electronic blasting systems, discusses the components and designs of electronic detonators, and provides a number of advantages of the electronic systems in conditioning of the the preparation of blasted rock. A conclusion is made that blasting with electronic detonators and the use of their advantages will help to reduce the specific consumption of explosives and the scope of drilling operations due to larger blasthole patterns.

Study on the liquefaction characteristics of saturated sands by millisecond delay blasting

The liquefaction in saturated sands under blast loading is an important research topic in geotechnical engineering. The effect of blast loading on the liquefaction characteristics of saturated sands was studied through a large-scale millisecond delay blasting (MDB) liquefaction field test. Based on the field test, a numerical model was established by the LS-DYNA finite element program to study the propagation of blast waves and the effects of explosive mass, scaled distance, and blast delay on the liquefaction characteristics of saturated sands. The results show that there was a significant sand boiling phenomenon in saturated sands under blast loading, and high values of the excess pore water pressure ratio were observed at monitoring points during the field test. The numerical simulation results show that the scaled distance and the blast delay significantly affected the excess pore water pressure. While the blast delay increased from 110 ms to 330 ms, the excess pore water pressure of the central area can increase by more than 18%. Based on the field and numerical tests, an empirical equation is established that can take into account both the scaled distance and blast delay, which provides a theoretical basis for future large-scale liquefaction sites by MDB.

Molecular concordance of methicillin-resistant Staphylococcus aureus isolates from healthcare workers and patients.

Methicillin-resistant Staphylococcus aureus (MRSA) is a significant nosocomial pathogen in the ICU. MRSA contamination of healthcare personnel (HCP) gloves and gowns after providing care to patients with MRSA occurs at a rate of 14%-16% in the ICU setting. Little is known about whether the MRSA isolates identified on HCP gown and gloves following patient care activities are the same as MRSA isolates identified as colonizing or infecting the patient. From a multisite cohort of 388 independent patient MRSA isolates and their corresponding HCP gown and glove isolates, we selected 91 isolates pairs using a probability to proportion size (PPS) sampling method. To determine whether the patient and HCP gown or gloves isolates were genetically similar, we used 5 comparative genomic typing methods: phylogenetic analysis, spa typing, multilocus sequence typing (MLST), large-scale BLAST score ratio (LSBSR), and single-nucleotide variant (SNV) analysis. We identified that 56 (61.5%) of isolate pairs were genetically similar at least by 4 of the methods. Comparably, the spa typing and the LSBSR analyses revealed that >75% of the examined isolate pairs were concordant, with the thresholds established for each analysis. Many of the patient MRSA isolates were genetically similar to those on the HCP gown or gloves following a patient care activity. This finding indicates that the patient is often the primary source of the MRSA isolates transmitted to the HCP, which can potentially be spread to other patients or hospital settings through HCP vectors. These results have important implications because they provide additional evidence for hospitals considering ending the use of contact precautions (gloves and gowns) for MRSA patients.

Nearsurface Air Layer Pollution with Micronic Dust Particles in Large-Scale Blasting in Open Pit Mining

Nearsurface Air Layer Pollution with Micronic Dust Particles in Large-Scale Blasting in Open Pit Mining

Investigation of the Reaction Kinetics of a Sinter-Reduction Process in the Thermal Reserve Zone of a Blast Furnace Using a Modified Sectioning Method

With the development of large-scale and high-performing blast furnaces, it is necessary to extensively study the reaction characteristics and related kinetic parameters of sinters in their heat reserve area. Under reducing atmosphere conditions, the reduction of iron oxide in sinter is closely related to the gasification reaction of coke. Based on a simulation experiment, the transition point from chemical reactions to diffusion and the related kinetic parameters were determined through a sectioning method. The results showed that increasing the proportion of low-grade coke increased the chemical-reaction rate, but it slightly decreased the mass-transfer and diffusion rates. An increase in the coke particle size increased the chemical-reaction, mass-transfer, and diffusion rates. However, an increase in the CO2 volume fraction in gas reduced the chemical-reaction, diffusion, and mass-transfer rates. The mixing ratio of coke and sinters increased the chemical-reaction rate, but it decreased the mass-transfer and diffusion rates. The rate constant of the chemical reactions in the early stage was three orders of magnitude higher than that of the diffusion and mass-transfer coefficients, and the fitting degree was obviously better than that of the molecular diffusion in the later stage. Based on the thermodynamics of irreversible processes, the interference of the chemical reactions with the diffusion and mass transfer in the near-equilibrium region was tentatively established, the method of controlling coke diffusion and mass transfer in the later reaction stage was given and related kinetic parameters were corrected, and further improvement of the modified sectioning method was completed.

Experimental study on damage magnification effect of lightweight auxetic honeycomb protective panels under close-in blast loads

Sandwich panels/sacrificial cladding systems composed of an auxetic core sandwiched between two faceplates can be considered an effective protective measure for reinforced concrete structures from blast loads. In this study, the effectiveness of re-entrant honeycomb core sandwich (RHS) protective panel systems, which exhibit a negative Poisson’s ratio, to protect one-way simply supported reinforced concrete (RC) slabs subjected to a close-range detonation from high explosive charges was experimentally evaluated. Three large-scale field blast trials were carried out, namely an RC slab without protection as the reference test and two RC slabs with RHS protective systems under similar blast loading conditions. The RC slabs with RHS protective systems experienced catastrophic failure, unlike the unprotected reference slab that experienced only localised concrete damage. LS-DYNA numerical models were validated and agreed well with the experimental results. It was demonstrated that the transferred blast impulse to the main structure can be magnified by a factor of 1.6 by using an RHS protective system compared to an unprotected structure. Furthermore, the effect of the mass of the protective system was numerically studied. The numerical results showed that the blast protection level of the main structure is governed by the inertial resistance of the protective system rather than through energy absorption of the auxetic honeycomb core structure.

Using Dictyostelium discoideum as a model for phagocytosis resistance in Escherichia coli

Abstract Escherichia coli related illnesses continue to be a problem around the world, especially in developing countries that lack clean water and proper sanitation. Dictyostelium discoideum is a soil dwelling amoeba that phagocytizes bacteria for nutrients. D. discoideum is a great model to study host pathogen interactions, and it has been used to identify virulence factors in bacteria. Our objective is to use Dictyostelium discoideum as a model to identify bacterial genes involved in resistance to phagocytosis. We hypothesize that D. discoideum can be used as a model organism to identify virulence genes associated with E. coli. The aims of this study are to identify E. coli genes predicted to grant resistance to D. discoideum grazing and phagocytosis and further characterize genes identified as potential virulence factors and observe the genes’ effects on D. discoideum grazing and phagocytic killing. Intestinal pathogenic, extraintestinal pathogenic, and laboratory E. coli strains were classified according to grazing phenotype. Previous comparative genomic analysis by large-scale BLAST score ratio (LS-BSR) identified genes prevalent amongst strains resistant to D. discoideum grazing. The gene gipA (growth in Peyer’s patches) was one gene found in various E. coli strains resistant to D. discoideum grazing. We are currently working to characterize the role of E. coli genes associated with resistance to D. discoideum grazing by manipulating E. coli strains for expression of these genes. We will observe the interactions between these strains and D. discoideum grazing and phagocytosis. This experiment will give insight into bacterial genes and virulence factors responsible for evading phagocytosis and the immune system. This project was funded in part by federal funds from the National Institute of Allergy and Infectious Diseases, National Institute of Health, and Department of Health and Human Services under grant number U19 AI110820. Dr. M. Snyder was funded by an NIH NIGMS grant F33 GM116618, a Franklin Research Grant from the American Philosophical Society and a grant from the TU FDRC committee. This research was also supported by an NIH NIGMS R25 GM19970.