Breaking Process Research Articles

Breaking Cyclic Dependencies for Network Calculus using Service Partitioning

Network Calculus (NC) is a method for providing certification evidence in networked systems, ensuring proper functioning of time-critical traffic. Traditional NC analyses focus on feedforward networks that are networks without cyclic dependencies. However, some methods, like the fix-point method and turn prohibition, apply NC to non-feedforward networks but exhibit limitations in stability, adaptability, and flexibility. We propose an alternative method, service partitioning, supported by theorems and lemmas, to address these limitations. Service partitioning breaks cyclic dependencies in non-feedforward networks using a breaking method that leverages Quality of Service (QoS) mechanisms (Weighted Round-Robin, Static Priority, Time-Aware Shaper), by assigning flows that form cycles to distinct buffers with dedicated service allocations. This method offers enhanced flexibility by allocating different network resources to buffers based on multi-class scheduling during the breaking process. In contrast to existing methods, service partitioning does not require rerouting or additional hardware and avoids deriving invalid solutions. The paper investigates the performance of service partitioning in terms of flexibility, result tightness, adaptability, and stability to show that service partitioning is superior to existing methods. One limitation of service partitioning is that it cannot fully break cyclic dependencies in some scenarios, requiring the assist from solving methods, which can be used to apply network calculus to networks with cyclic dependencies. However, when combined with solving methods, service partitioning can still improve solution quality, reducing potentially invalid results in simulated ring networks by over 30% compared with results derived by solving methods alone.

Resection of DNA double-strand breaks activates Mre11-Rad50-Nbs1- and Rad9-Hus1-Rad1-dependent mechanisms that redundantly promote ATR checkpoint activation and end processing in Xenopus egg extracts.

Sensing and processing of DNA double-strand breaks (DSBs) are vital to genome stability. DSBs are primarily detected by the ATM checkpoint pathway, where the Mre11-Rad50-Nbs1 (MRN) complex serves as the DSB sensor. Subsequent DSB end resection activates the ATR checkpoint pathway, where replication protein A, MRN, and the Rad9-Hus1-Rad1 (9-1-1) clamp serve as the DNA structure sensors. ATR activation depends also on Topbp1, which is loaded onto DNA through multiple mechanisms. While different DNA structures elicit specific ATR-activation subpathways, the regulation and mechanisms of the ATR-activation subpathways are not fully understood. Using DNA substrates that mimic extensively resected DSBs, we show here that MRN and 9-1-1 redundantly stimulate Dna2-dependent long-range end resection and ATR activation in Xenopus egg extracts. MRN serves as the loading platform for ATM, which, in turn, stimulates Dna2- and Topbp1-loading. Nevertheless, MRN promotes Dna2-mediated end processing largely independently of ATM. 9-1-1 is dispensable for bulk Dna2 loading, and Topbp1 loading is interdependent with 9-1-1. ATR facilitates Mre11 phosphorylation and ATM dissociation. These data uncover that long-range end resection activates two redundant pathways that facilitate ATR checkpoint signaling and DNA processing in a vertebrate system.

Measurement of the Promoting Effect of Complex Conditions on the Adhesion Development in Curing Process of Cold Recycling Mixture with Emulsified Asphalt

The curing process of cold recycling mixture with emulsified asphalt is a process of emulsion breaking, water evaporation, and cement hydration, resulting in adhesion development and strength formation. There are many factors that affect this process, including curing temperature, curing time, reclaimed asphalt pavement (RAP) contents, and cement contents. However, the evaluation of the promoting effect of each factor is still not quite clear. Hence, in this paper, the curing temperature, curing time, and RAP contents were discussed to find out the dominating factor in this process. The development of moisture loss and indirect tensile strength (ITS) was measured and analyzed through establishing prediction models between them and curing time. Besides, the functional relationship between moisture loss and ITS was also analyzed to evaluate the promoting effect of each factor. The results showed that the curing temperature has a certain impact on the development of moisture loss and ITS and an increase in curing temperature would accelerate the reaction rate, while RAP contents can hardly affect this process. Through functional relationship between moisture loss and ITS, it was found that the development of early strength and adhesion was dominated by ITS despite the increase of curing temperature and RAP contents. Expanding the hydration effect of cement could promote the curing process. However, this dominating role weakened at higher temperature and moisture loss should be treated more carefully.

Carbon-Atom Exchange between [MC2]+ (M = Os and Ir) and Methane: on the Thermodynamic and Dynamic Aspects.

Gas-phase reactions of [OsC2]+ and [IrC2]+ with methane at ambient temperature have been studied using quadrupole-ion trap mass spectrometry combined with quantum chemical calculations. Both [OsC2]+ and [IrC2]+ undergo carbon-atom exchange reactions with methane. The associated mechanisms for the two systems are found to be similar. The differences in the rates of carbon isotope exchange reactions of methane with [MC2]+ (M = Os and Ir) are explained by several factors like the energy barrier for the initial H3C-H bond breaking processes, the molecular dynamics, orbital interactions, and the H-binding energies of the pivotal steps. Besides, the number of participating valence orbitals might be one of the keys to regulate the rate in the key step. The present findings may provide useful ideas and inspiration for designing similar processes.

The design of chip breaking grooves for spade drill inserts

A chip breaking groove was designed on a spade drill insert to break chips. The effects of the anti-chip angle, width and height of chip breaking groove on the chip curl radius were investigated with simulations and drilling experiments. The forces acting on the chip were analyzed to clarify the chip breaking processes. The chip breaking process of a spade drill insert with chip breaking groove was simulated with the finite element technique to study the chip breaking mechanism. The calculation formulas for calculating the width, height and radius of the chip breaking groove were established. The research results show that the chip curl radius is affected by the chip breaking groove parameters. The chip curl radius increases with the anti-chip angle but decreases as width decreases or height increases. When the values of anti-chip angle, width and height of chip breaking groove reach thresholds, the chip wind or piling phenomenon will occur during the drilling experiments. The formulas for calculating chip breaking grooves are feasible. A design method of chip breaking grooves for spade drill inserts is proposed. Spade drill inserts whose chip breaking groove parameters are calculated according to formulas of the width, height and radius can effectively break chips at different drilling parameters.

Abstract A034: Development of a novel class of genomic biomarkers through mathematical modeling of cancer genome contiguity

Abstract Introduction: Chromosomal instability (CIN) is a hallmark of cancer aggressiveness. However, in lung adenocarcinoma (LUAD) the most common methods for measuring genomic instability, such as the weighted Genome Instability Index (wGII), are not reliable predictors of patient outcomes. The wGII measures the portion of the genome altered by copy number variation (CNV). The wGII quantifies aneuploidy but ignores other properties of CNVs such as their length distribution. We hypothesized that quantification of genome contiguity may overcome the limitations of wGII and help identify novel prognostic biomarkers. Method: We develop a novel measure of CIN based on mathematical modeling of genome breakage patterns. Utilizing segmented CNV profiles we infer two properties of the genome breakage process – its intensity and dispersion. Intensity is proportional to the number of genome breakpoints and is estimated by the total number of CNV segments. Dispersion quantifies spatial dependence of breakpoints over a wide range of genomic scales. It is computed by Ripley’s K-function which compares the distribution of breakpoints with a random Poisson point process. Jointly, intensity and dispersion, which we term the weighted Genome Contiguity Index (wGCI), estimate the contiguity of the genome. We contrast the wGCI with a heuristic score based on quantiles of segment lengths. Results: We sought to evaluate the association between the wGCI and patients’ survival in a proteogenomic cohort of 215 primary LUAD tumors profiled using whole-genome sequencing (WGS). In support of our hypothesis, we observed that patients had significantly better outcomes if their tumor genomes had longer segments compared to those with a high degree of fragmentation (P=0.014). Utilizing the wGCI, we found that tumor genomes with dispersed breakage (and low contiguity) were associated with worst outcomes (P=0.01). To identify mechanisms associated with dispersed breakage patterns we compared genomic features of the two groups. We found that LUAD tumors with highly fragmented genomes have a higher rate of TERT amplifications (P=0.005) and increased TERT RNA expression (P=2e-6). These tumors are also enriched for TP53 mutations (P=2e-16) and MYC amplifications (P=0.01). Given the cost and practical challenges of clinical WGS we leveraged mass-spectrometry proteomics to identify protein biomarkers. We found IGF2BP3 to be significantly upregulated (P=0.0006) in highly fragmented tumors and to be associated with worse outcomes (P=0.011). We use immunohistochemistry (IHC) to develop and validate IGF2BP3 as a prognostic biomarker in independent lung cancer cohorts. Conclusion: We introduced a novel quantitative measure of CIN that uniquely captures the impact of chromosome breakage on LUAD patients' clinical outcomes. Further, we identified upregulation of IGF2BP3 as a proxy to identify fragmented genomes using IHC. Our work underscores the value of mathematical modeling of genome breakage patterns to develop complex genomic biomarkers. Citation Format: Noshad Hosseini, Rahul Mannan, Alexey Nesvizhskii, Saravana Dhanasekaran, Marcin Cieslik. Development of a novel class of genomic biomarkers through mathematical modeling of cancer genome contiguity [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: DNA Damage Repair: From Basic Science to Future Clinical Application; 2024 Jan 9-11; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2024;84(1 Suppl):Abstract nr A034.

Study conical pick cutting performance and fatigue life in breaking rock plate process with numerical simulation

The fatigue life and cutting performance of conical pick is essential for the roadheader machine in the excavation engineering. In rock breaking process, the rock structural conditions has a certain influence on the rock breaking and rock damage with roadheader breaking rock. Established the simulation model of conical pick cutting jointed rock to investigate the influence of the rock joint, rock bedding and confining pressure on the cutting performance and fatigue life of conical pick and rock damage. And the MATLAB is applied to solve the difficulty of rock damage statistical analysis. The research results indicated that the cutting force decreases with the rock joint length increasing, the cutting force increases first and decreases with the rock bedding angle increasing, however, the cutting force decreases first and then increases with the confining pressure increasing. The rock damage has a great relationship with the rock joint, rock bedding and confining pressure. The rock damage increases first and decreases then with the rock joint increasing and the rock bedding angle increasing. However, the influence of confining pressure on rock damage is contrary. Meanwhile, the rock fracture volume is positively correlated with damage value. The research results indicated that the rock structural parameters have an obvious influence on conical pick cutting performance and rock damage.

Exact Solutions of Population Balance Equation with Aggregation, Nucleation, Growth and Breakage Processes, Using Scaling Group Analysis

Population balance equations may be employed to handle a wide variety of particle processes has certainly received unprecedented attention, but the absence of explicit exact solutions necessitates the use of numerical approaches. In this paper, a (2 + 1) dimensional population balance equation with aggregation, nucleation, growth and breakage processes is solved analytically by use of the methods of scaling transformation group, observation and trial function. Symmetries, reduced equations, invariant solutions, exact solutions, existence of solutions, evolution analysis of dynamic behavior for solutions are presented. The exact solutions obtained can be compared with the numerical scheme. The obtained results also show that the method of scaling transformation group can be applied to study integro-partial differential equations.

Numerical Investigations for Rock-Breaking Process and Cutter Layout Optimization of a PDC Drill Bit with Dual-Cutter

PDC (polycrystalline diamond compact) drill bits are widely employed for rock-breaking in many industries like underground engineering and building constructions. The cutter layout would directly affect the overall performance of the drill bits. Field applications show that the staggered cutter layout strategy of dual-cutter can increase the drilling efficiency of the PDC bit. In order to explore the rock breaking mechanism of this type of drill bit, a numerical model of a dual-cutter and rock breaking with damage evolution based on a hybrid finite and cohesive element method (FCEM) has been established in this work. The model is verified through Brazilian disk tests. The rock breaking processes of this type of bit have been analyzed, including crack initiation, propagation, and the formation of rock debris. Moreover, the effects of horizontal and vertical offset of the back cutter on the MSE (mechanical special energy) have been investigated. Results demonstrate that the dual-cutter can prominently reduce the MSE compared to a single-cutter. The vertical offset of the back cutter has a minor effect on the MSE, while the horizontal offset is of great significance on the MSE. On this basis, the relationships between the MSE and both the vertical and horizontal offset coefficients have been built based on the response surface methodology (RSM). Finally, an optimized layout solution, with optimal vertical and horizontal offset coefficients of 0.641 and 0.497, is determined via the Gray Wolf algorithm.

A cobalt(II) coordination polymer-derived catalyst engineered via temperature-induced semi-reversible single-crystal-to-single-crystal (SCSC) dehydration for efficient liquid-phase epoxidation of olefins.

Single-crystal-to-single-crystal (SCSC) transformations provide more avenues for phase transitions, which have piqued great interest in crystal engineering. In this work, a 3D Co(II)-based coordination polymer (CP), {Co2(OH2)8(btec)}·4H2O (1), (where (btec)4- = 1,2,4,5-benzenetetracarboxylate) undergoes SCSC transition upon heating at 180 °C to afford an anhydrous phase [Co2(btec)] (1'). Room-temperature water-vapour induced semi-reversible SCSC transformation of 1' involves condensation of two water molecules coordinating to the metal cluster, yielding a new framework [Co2(OH2)2(btec)] (2). These SCSC transitions were accomplished through a sequential bond breaking and new bond formation process which was accompanied by colour changes from orange (1) → violet (1') → pink (2). All materials were structurally elucidated by single-crystal X-ray diffraction (SCXRD) and further established by various analytical techniques. According to SCXRD data, all the frameworks possess octahedral geometries around the cobalt(II) sphere. SCXRD studies further revealed that 1 is a polymeric architecture with a binodal 4-c sql topology while 1' and 2 possess (3,6)-c kgd and (4,6)-c scu 3D nets, respectively. By virtue of multitopicity exhibited by the tetracarboxylate, the coordination number of the linker around the Co(II) sphere increased from four (in 1) to eight (in 1') and then decreased to six (in 2). Most interestingly, permanent porosity could be observed for the dihydrate 2, originated from potential void space as substantiated by dinitrogen (N2) sorption isotherm. These porous frameworks were active catalysts for the aerobic epoxidation of the model substrate cyclohexene using molecular oxygen (O2) as the final oxidant in the presence of the sacrificial i-butyraldehyde (IBA) reductant. For using the dihydrous phase 2, cyclohexene and various other olefins were catalytically oxidised to their corresponding epoxides with up to 38.5% conversion and 99.0% selectivity. The catalyst 2 can be expediently recycled in four runs without significant loss of activity. This research demonstrates that a little innovation in the active-site-engineered organic-inorganic hybrid materials can significantly enhance the catalytic performance and selectivity of coordination polymer-derived heterogeneous catalysts.

Identification of the oversized rock pieces in hydraulic hammer breaking process based on the scanner data geometry features analysis

Due to the harsh conditions in the mining environment, it is difficult to fully automate some of the tasks carried out by mining machines and devices. As part of the technological process of extracting copper ore from Polish mines, the material is broken with a hammer to fit through the screen of a 40×40 cm square shape slot, after which it is loaded and conveyed for further processing. Usually, most of the material remaining on the screen cannot be considered oversized, additionally smaller particles can form blockages or rest on larger blocks. In this case, the crushing is not necessary, and only its movement may be sufficient. The focus of the presented research is on the identification of the particles that would be considered oversized, as it is a crucial task in the breaking hammer automation process. The authors propose a method based on the analysis of initially extracted 3D data copper ore blocks obtained from laser scanning at one of the transfer stations in KGHM Polska Miedź S.A., Polkowice-Sieroszowice mine. The difficulties of measurement are multiplied by the necessity of performing the scan from a single point of view, which was forced by safety concerns. Segmented but incomplete 3D data are processed, which results in finding the geometric features that prevent the material from going through the screen in an automatic manner.

A new approach to detect long memory by fractional integration or short memory by structural break

<abstract> <p>Long memory in test statistics can either originate from fractional integration or be spuriously induced by a short memory process with a structural break. This research estimated and detected long memory from the two causes by simulations and empirical analysis. The simulation results showed that fractional integration and structural break processes could demonstrate long memory properties. The 2ELW estimator was stable for fractional integration but not stable for time series with structural breaks. The modified W statistic based on 2ELW was efficient in discriminating fractional integration and structural breaks. Moreover, we found that six volatility time series of stock indexes and individual stocks in the Chinese market experience significant long memory and structural breaks, and the fractional differencing parameter is overestimated without controlling structural breaks.</p> </abstract>

Experimental study on break and velocity characteristics of liquid column between horizontal tubes

Column flow is one major flow mode in horizontal-tube falling-film evaporator. In this study, a horizontal-tube falling-film flow experiment platform is built up. A high-speed camera is used to shoot the process of falling and break of liquid column at the bottom of horizontal tube. Image edges are detected using the algorithm based on Sobel to quantify the liquid column features. Liquid column break process, falling velocity, variation pattern of break shape and break length, as well as the special phenomenon encountered in column falling process are discussed in detail. Results show that the break of liquid column undergoes three stages. The liquid column break shape has a periodic variation pattern, and the liquid column break length fluctuates within a certain interval. In addition, as the spray increases, break length increases, and the fluctuation interval of break length expands. The liquid falls downward spirally and its velocity rises in waves with time, and there exists an obvious uniform phase. In spray density range of 0.03–0.05 kg/m⋅s, liquid column falling velocity increases and the uniform phase is delayed as the spray increases. But when spray density varies in 0.05–0.06 kg/m⋅s, no significant increase in liquid falling velocity can be found.

Structure Design of Bionic PDC Cutter and the Characteristics of Rock Breaking Processes

The rational structural design of polycrystalline diamond compact (PDC) cutters effectively enhances the performance of drill bits in rock fragmentation and extends their service life. Inspired by bionics, a bionic PDC cutter was designed, taking the mole claw toe, shark tooth, and microscopic biomaterial structures as the bionic prototypes. To verify its rock-breaking effectiveness, the finite element method was employed to compare the rock-breaking processes of the bionic cutter, triangular prism cutter, and axe cutter. The study also investigated the influence of different back rake angles, cutting depths, arc radii, and hydrostatic pressures on rock breaking using the bionic cutter. Prior to this, the accuracy of the finite element model was validated through laboratory tests. Subsequently, a drill bit incorporating all three types of cutters was constructed, and simulations of rock breaking were conducted on a full-sized drill bit. The results demonstrate that the bionic cutter exhibits superior load concentration on the rock compared to the triangular prism cutter and the axe cutter. Additionally, its arc structure facilitates the “shoveling” of the rock, making it more susceptible to breakage under tensile stress. As a result, the efficiency of the bionic cutter surpasses that of the triangular prism and axe cutters. Similarly, it exhibits minimal fluctuations and values in cutting force. As the back rake angle and cutting depth increase, the MSE and cutting force of all three cutters also increase. However, the bionic cutter consistently maintains the lowest MSE and cutting force, confirming the superiority of its bionic structural design. The MSE and cutting force of the bionic cutter fluctuate with the increase of the arc radius, and the optimal arc radius falls within the simulation range, between 21 mm and 23 mm. Compared to the other two types of cutters, bionic cutters possess a unique structure that allows for better release of internal stress within the rock, thereby ensuring higher efficiency in rock-breaking, particularly in deep geological formations. The rock breaking simulation results of full-sized drill bits show that the use of a bionic cutter can improve the drill bit’s ability to penetrate the formation, reduce the possibility of drill bit bounce during the rock breaking process, prevent the occurrence of stick-slip, improve the drilling stability, effectively improve the efficiency and service life of the drill bit during the rock breaking process, and reduce the drilling cost. It is concluded that the research results of bionic PDC cutters are helpful to the development of high-performance drill bits and the reduction of drilling costs.

Study on the Formation Characteristics and Disaster Mitigation Mechanisms of Rip Currents on Arc-Shaped Beach

Rip currents are fast offshore currents generated during the breaking process of waves propagating nearshore, posing a potential life safety threat to coastal bathers. This study utilizes a Boussinesq phase-resolving model to investigate the formation mechanism of rip currents at Dadonghai Beach, based on its actual topography, and explores the characteristics of rip current formation under various wave conditions, with an emphasis on analyzing vortices, the mean water level and the spatial distribution of average velocity. The results indicate that rip current formation is significantly influenced by wave height and period. The increase in wave height and period results in more intense rip currents and higher water level fluctuations on arc-shaped beaches and on both sides of the bay, leading to complex vortex distributions. An increase in the angle of wave incidence hinders rip current formation in arc-shaped beach areas but is favorable to the generation of deflection rips on both sides of the bay. Furthermore, an increase in bottom friction inhibits rip current formation. When the water depth decreases in the channels, rip currents transition into longshore currents. The findings of this research offer valuable scientific insights into the formation mechanisms of rip currents and contribute to their prediction and prevention.

Numerical Simulation of Flow and Argon Bubble Distribution in a Continuous Casting Slab Mold under Different Argon Injection Modes

A three-dimensional model is established to investigate the effect of argon injection mode, argon flow rate and casting speed on the gas–liquid two-phase flow behavior inside a slab continuous casting mold. The Eulerian–Eulerian model is employed to simulate the gas–liquid flow, and the population balance model is applied to describe the bubble breakage and coalescence process in the mold. The numerical simulation results of the bubble size distribution are verified using the water model experiment. The results show that the flow field and bubble distribution are similar between the argon injection at the upper submerged entry nozzle (SEN) and tundish upper nozzle (TUN), while the number density is larger for the argon injection of TUN. The coalescence rate of bubbles and the bubble size inside the mold increase with increasing argon flow rate. When the argon flow rate exceeds 4 L/min, the flow pattern of liquid steel changes from double-roll flow to complex flow, with aggravation of the level fluctuation of the top surface near the SEN. When the casting speed increases, the bubble breakup rate increases and results in a decrease in the size of bubbles inside the mold. At a high casting speed, the flow pattern tends to form double-roll flow, and the liquid level at the narrow face of the top surface increases.

An improved neurogenetic model for recognition of 3D kinetic data of human extracted from the Vicon Robot system

These days, it is crucial to discern between different types of human behavior, and artificial intelligence techniques play a big part in that. The characteristics of the feedforward artificial neural network (FANN) algorithm and the genetic algorithm have been combined to create an important working mechanism that aids in this field. The proposed system can be used for essential tasks in life, such as analysis, automation, control, recognition, and other tasks. Crossover and mutation are the two primary mechanisms used by the genetic algorithm in the proposed system to replace the back propagation process in ANN. While the feedforward artificial neural network technique is focused on input processing, this should be based on the process of breaking the feedforward artificial neural network algorithm. Additionally, the result is computed from each ANN during the breaking up process, which is based on the breaking up of the artificial neural network algorithm into multiple ANNs based on the number of ANN layers, and therefore, each layer in the original artificial neural network algorithm is assessed. The best layers are chosen for the crossover phase after the breakage process, while the other layers go through the mutation process. The output of this generation is then determined by combining the artificial neural networks into a single ANN; the outcome is then checked to see if the process needs to create a new generation. The system performed well and produced accurate findings when it was used with data taken from the Vicon Robot system, which was primarily designed to record human behaviors based on three coordinates and classify them as either normal or aggressive.

Dynamic characteristic response of PDC bit vibration coupled with drill string dynamics

A thorough understanding of the rock breaking process is key to increasing the rate of penetration and reducing bit wear. Currently, many models of drill bit–rock interaction have been developed. However, these models inaccurately reflect the complex movement of polycrystalline diamond compact (PDC) bits in the well. In this study, the finite element method was used to discretize and simulate the rock removal process, and drill string nodes were taken as the boundary conditions of drill bit movement. A model combining drill string dynamics and drill bit–rock interaction was established to describe the complex dynamic behavior of a PDC bit in a well. The accuracy of the model was verified by a PDC bit drilling experiment. Then, the influences of rock type, weight on bit (WOB), rotational speed, and PDC bit blade number on PDC bit vibration characteristics were studied. Results show that drill bit vibration is stronger when drilling in rocks with high hardness and roughness, and the bit runs more smoothly with more blades. Therefore, drill bits with more blades should be used when drilling hard rocks. Bit vibration is enhanced by increasing rotational speed and WOB, but the effect of rotational speed on bit vibration is much smaller than that of WOB.

Effect on ignition sensitivity of combustible dust particle size reduction due to dispersion in the 20-L chamber

This work simulates the particle breakage process caused by the dispersion of several typical combustible dusts in a 20-L chamber. Some operations in the process industry that involve gas turbulence and particle interactions can cause dust particles to break, resulting in a decrease in minimum ignition energy (MIE) and minimum ignition temperature (MIT). Particle breakage classification should attempt to correlate changes in D3,2 (Sauter mean diameter) values with the brittleness index. The descending order of particle breakage severity is as follows: ascorbic acid > anthraquinone > tobacco > nicotinic acid > lignite. The percentage decrease in MIE and MIT values is generally proportional to the degree of particle breakage. However, the decrease in MIT values was not as significant as in MIE values. This is because of the various dust-ignition source interaction patterns between a dust cloud and an ignition source.

The role of halogens in Au–S bond cleavage for energy-differentiated catalysis at the single-bond limit

The transformation from one compound to another involves the breaking and formation of chemical bonds at the single-bond level, especially during catalytic reactions that are of great significance in broad fields such as energy conversion, environmental science, life science and chemical synthesis. The study of the reaction process at the single-bond limit is the key to understanding the catalytic reaction mechanism and further rationally designing catalysts. Here, we develop a method to monitor the catalytic process from the perspective of the single-bond energy using high-resolution scanning tunneling microscopy single-molecule junctions. Experimental and theoretical studies consistently reveal that the attack of a halogen atom on an Au atom can reduce the breaking energy of Au−S bonds, thereby accelerating the bond cleavage reaction and shortening the plateau length during the single-molecule junction breaking. Furthermore, the distinction in catalytic activity between different halogen atoms can be compared as well. This study establishes the intrinsic relationship among the reaction activation energy, the chemical bond breaking energy and the single-molecule junction breaking process, strengthening our mastery of catalytic reactions towards precise chemistry.