Collision Theory Research Articles

Impact of Temperature on Reaction Rate in Catalytic Reactions

Purpose: The aim of the study was to assess the impact of temperature on reaction rate in catalytic reactions. Methodology: This study adopted a desk methodology. A desk study research design is commonly known as secondary data collection. This is basically collecting data from existing resources preferably because of its low cost advantage as compared to a field research. Our current study looked into already published studies and reports as the data was easily accessed through online journals and libraries. Findings: The study indicated that as higher temperatures generally increase the rate at which reactions occur. This is due to the fact that elevated temperatures provide the reactant molecules with more kinetic energy, enabling them to collide more frequently and with greater force, which is necessary to overcome the activation energy barrier. In catalytic reactions, temperature not only accelerates the intrinsic rate of the reaction but can also affect the activity and selectivity of the catalyst. However, too high a temperature can lead to catalyst deactivation through processes such as sintering or coke formation, where the catalyst surface is altered or blocked. Thus, an optimal temperature range is crucial to balance enhanced reaction rates while maintaining catalyst integrity and performance. Implications to Theory, Practice and Policy: Arrhenius equation, transition state theory and collision theory may be used to anchor future studies on the impact of temperature on reaction rate in catalytic reactions. In practical applications, industries should implement advanced temperature control systems to maintain optimal reaction conditions during catalytic processes. Policymakers have a critical role in shaping the landscape of catalytic reactions by developing regulatory guidelines focused on temperature management.

Dynamic Analysis of Metamorphic Mechanisms with Impact Effects During Configuration Transformation

Metamorphic mechanisms have attracted considerable attention owing to their capability to switch their topology to adapt to different operational tasks. One feature of topological change is the re-contact of different bodies, which inevitably causes collisions affecting operation accuracy and service life. Consequently, in this study, a collision incidence matrix was introduced to describe the topology of a system involved in collisions, and a method for reducing the closed-loop system to an open-loop system was proposed. The complex movement of the metamorphic mechanism in a changing topology was classified into two different running stages of the source metamorphic mechanism. Based on the relative coordinate method, dynamic modeling of the source metamorphic mechanism considering the impact effects was conducted. Combining the classical collision theory and Newton–Euler equation, the generated impact impulse and the motion after collision were determined. Subsequently, a dynamic analytical method for the full configuration of metamorphic mechanisms was proposed to reflect the changes in the topological structure in the dynamic model. Finally, two typical metamorphic mechanisms used in packaging and spinning were considered as examples to verify the correctness and effectiveness of the proposed method, and their impact characteristics during configuration transformation were analyzed. The proposed analytical method of internal impact for a variable topology process provides effective theoretical guidance for the stability analysis of configuration transformation and structural design aimed at minimizing impacts.

Effect of Catalyst Concentration on Reaction Rate in Organic Synthesis in Kenya

Purpose: The aim of the study was to assess the effect of catalyst concentration on reaction rate in organic synthesis in Kenya. Methodology: This study adopted a desk methodology. A desk study research design is commonly known as secondary data collection. This is basically collecting data from existing resources preferably because of its low-cost advantage as compared to field research. Our current study looked into already published studies and reports as the data was easily accessed through online journals and libraries. Findings: Increased catalyst concentration typically enhances the reaction rate by providing more active sites for the reactants to interact, thereby accelerating the reaction process. This phenomenon follows the principles of collision theory, which states that a higher concentration of catalyst molecules leads to more frequent collisions with reactant molecules, thus increasing the likelihood of successful reactions. Studies have shown that in many organic syntheses, an optimal catalyst concentration exists where the reaction rate is maximized; beyond this point, further increases in catalyst concentration may result in negligible improvements or even adverse effects due to catalyst aggregation or inhibition. Additionally, the nature of the catalyst, its dispersion in the reaction medium, and the specific reaction mechanism all play significant roles in determining the overall impact of catalyst concentration on reaction kinetics. Consequently, fine-tuning the catalyst concentration is essential for optimizing reaction conditions, improving yields, and achieving desired product selectivity in organic synthesis. Implications to Theory, Practice and Policy: Transition state theory, collision theory and michaelis menten kinetics may be used to anchor future studies on assessing effect of catalyst concentration on reaction rate in organic synthesis in Kenya. Practical guidelines are crucial for optimizing catalyst concentration in specific reaction types and industrial settings. Establishing regulatory frameworks that incentivize efficient catalyst concentration practices within industries is imperative.

Libepa — A C++/Python library for calculations of cross sections of ultraperipheral collisions

The library provides a set of C++/Python functions for computing cross sections of ultraperipheral collisions of high energy particles under the equivalent photons approximation. Cross sections are represented through multiple integrals over the phase space. The integrals are calculated through recurrent application of algorithms for one dimensional integration. The paper contains an introduction to the theory of ultraperipheral collisions, discusses the library approach and provides a few examples of calculations.

MaxKinEff: A Collision Theory-Based Approach for Analyzing Turnover Frequency and Turnover Number in Catalytic Processes.

The efficiency of catalysts relies on comprehending the underlying kinetics that govern their performance. Under the steady-state regime, the "rate" is referred to as the turnover frequency, where the reaction rate is first order with respect to catalysts. Here, we introduce the Maximum Kinetic Efficiency (MaxKinEff) model, grounded in collision theory, to predict efficiency based on maximum turnover frequency, and maximum turnover number, . The model was applied to molecular water oxidation using twenty-six transition metal catalysts from the first (3d), second (4d), and third (5d) rows. A thorough investigation reveals that [Ru(pda)(Br-py)2] (pda=1,10-phenanthroline-2,9-dicarboxylate; Py=pyridinophane) exhibits a notable of 1176.87×10-5 s-1 due to its larger collision diameter (σRC) and lower activation energy (Ea). Importantly, the trend in the computed values aligns with experimental TON, validating the model's accuracy. For instance, [Cp*Ir(κ2-N,O)NO3] is identified by MaxKinEff as a standout performer, with the normalized maximum computed TON, resembling the experimental TON, =2000.

Rearrangement collision theory of phonon-driven exciton dissociation

Understanding the processes governing the dissociation of excitons to free charge carriers in semiconductors and insulators is of central importance for photovoltaic applications. Dyson's S-matrix formalism provides a framework for computing scattering rates between quasiparticle states derived from the same underlying Hamiltonian, often reducing to familiar Fermi's “golden rule” like expressions at first order. By presenting a rigorous formalism for multichannel scattering, we extend this approach to describe scattering between composite quasiparticles and, in particular, the process of exciton dissociation mediated by the electron-phonon interaction. Subsequently, we derive rigorous expressions for the exciton dissociation rate, a key quantity of interest in optoelectronic materials, which enforce correct energy conservation and may be readily used in calculations. We apply our formalism to a three-dimensional model system to compare temperature-dependent exciton rates obtained for different scattering channels. Published by the American Physical Society 2024

Research on ship-ice collision model and ship-bow fatigue failure Mechanism based on elastic-plastic ice constitutive relation

Collisions between sea ice and ships can damage the hull structure and pose a threat to crew safety in severe cases. The modelling of ice materials is crucial, but it is difficult to study ice-ship interactions. In this study, an ice constitutive model including the temperature factor was verified through experiments and numerical simulations of uniaxial and triaxial compression. Furthermore, the effects of salinity and porosity on the compressive strength of ice were studied using experiments and numerical simulations. The mechanical behaviour of sea ice was then simulated using the constitutive model mentioned above. A numerical model of collisions between polar ships and sea ice was established to investigate the ice-breaking processes of ships under different working conditions. The collision force and the level of structural damage were obtained. The influences of the initial pore size, hull speed, bow angle, and bow shape on the collision force and structural damage in the ship-ice collision process were analysed. Finally, fatigue damage to the bow structure at different ice thicknesses and speeds was calculated. The present results provide a reference for the structural design and optimisation of polar ships to a certain extent and improve the theory of ship-ice collisions.

Rigid-flexible coupling dynamic modelling and dynamic accuracy analysis of planar cam four-bar mechanism with multiple clearance joints

Combination mechanism of conjugate cam and four-bar is a complex type of multi-body system, in which the coupling problems such as cam profile law, flexible deformation of connecting rods, and multiple joint clearance collision make it difficult to model and optimise its dynamics. Just as the beating-up mechanism of high-speed rapier looms for multi-layer weaving is a representative conjugate cam four-bar mechanism. In response to the current development of textile machinery in the direction of high-speed and precision, and in order to improve the work efficiency and operational accuracy of the conjugate cam four-bar beating-up mechanism, the following work is done for the purpose of taking into account the multi-joint clearance and the flexible rod based on the mechanism. Firstly, based on Kane's equation, a multi-body dynamic model with multiple clearances is established combined with clearance collision theory. Secondly, a dynamic model of a rigid-flexible coupling system with multiple revolute clearances is established using finite element method combined with modal synthesis technology. Subsequently, the variables separation method and mode superposition method are used to solve the dynamic equations of the coupled system. Finally, numerical examples are used to analyse the effects of clearance quantity, clearance size, mode truncation order, cam speed, and component material properties on the dynamic response and accuracy of the system. The results show that, in the rotational speed range of 600–800 rpm, the dynamic performance of the system is little affected by the speed; Through comparative analysis of multiple materials, it is found that selecting carbon fibre composite materials has the smallest impact on the motion accuracy of the system. In this paper, the clearance collision model, finite element model and rigid-flexible coupling dynamic model are integrated, which are applied to the cam-linkage combined multi-body mechanism, and the dynamic problems of the actual machine are analysed and solved.

Modeling collisional kinetic energy damping, heating, and cooling of ions in mass spectrometers: A tutorial perspective

Many powerful methods in mass spectrometry rely on activation of ions by high-energy collisions with gas particles. For example, multiple Collision Induced Dissociation (CID) has been used for many years to determine structural information for ions ranging from small organics to large, native-like protein complexes. More recently, Collision Induced Unfolding (CIU) has proved to be a very powerful method for understanding high-order protein structure and detecting differences between similar proteins. Quantifying the thermochemistry underlying dissociation/unfolding in these experiments can be quite challenging without reliable models of ion heating and cooling. Established physical models of CID are valuable in predicting ion heating but do not explicitly include mechanisms for cooling, which may play a large part in CID/CIU in modern instruments. Ab initio and Molecular Dynamics methods are extremely computationally expensive for modeling CID/CIU of large analytes such as biomolecular ions. In this tutorial perspective, limiting behaviors of ion kinetic energy damping, heating, and cooling set by “extreme” cases are explored, and an Improved Impulsive Collision Theory and associated software (“Ion Simulations of the Physics of Activation”, IonSPA) are introduced that can model all of these for partially inelastic collisions. Finally, examples of modeled collisional activation of native-like protein ions under realistic experimental conditions are discussed, with an outlook toward the use of IonSPA in accessing the thermochemical information hidden in CID breakdown curves and CIU fingerprints.

Transformation behavior of hazardous jarosite into recyclable hematite in a solution with high concentrations of K+ and Na+

Iron in the leaching solution with high K+ and Na+ concentrations was usually precipitated as the typical hazardous and toxic jarosite residues. However, this method of treatment has been greatly restricted by increasingly strict environmental regulations. Here we propose that iron can be precipitated from the solution with high K+ and Na+ concentrations as recyclable hematite products by adjusting the concentration ratio of sodium and potassium ions in the solution. The transformation behavior of jarosite into hematite in high concentration potassium ion and sodium ion solution was explained based on collision theory. The results indicated that in instances where the concentration ratio of Na+/K+ is ≥ 4:1, the iron present in the solution can be effectively precipitated as a recyclable hematite product, as opposed to forming the conventional hazardous jarosite residue, even under conditions where the potassium ion concentration reaches levels as high as 4 g/L. On the other hand, thermodynamic and molecular dynamics simulations indicate that at a temperature of 185 °C, the decomposition transformation of Na-jarosite (32.64 kJ and 7.25 eV) is more energetically advantageous compared to that of K-jarosite (61.07 kJ and 15.31 eV). The results were verified by the leaching solution from smelting industry. The iron content in the residues is above 58%, the sulfur content is below 4%, the zinc content is below 1%, and the total iron concentration in the supernatant is about 4 g/L, reaching the production index of the smelting industry. The green, environmentally friendly, and recyclable separation of iron in a solution with high concentrations of potassium and sodium ions is achieved, which is of great significance for the treatment of iron-containing solution and wastewater in the chemical industry and metallurgy fields.

Fundus image segmentation based on random collision whale optimization algorithm

Medical image segmentation is an important technical tool, OTSU algorithm is a common method in threshold segmentation, but with the increase of the number of threshold segmentation, the selection of its threshold is a big problem, and the segmentation effect is difficult to be guaranteed. In order to solve this problem, this paper proposes a random collision whale optimization algorithm to optimize OTSU for reliable image segmentation. The algorithm is called RCWOA for short. Firstly, the Halton sequence is used to uniformly initialize the population to make the population position distribution uniform, and then the dimensional Opposition-based learning of small-hole imaging is introduced to update the whale position and find out the missing feasible solution. Finally, the random collision theory is used to update the position of the optimal individual to improve the quality of the solution, At the same time, it also improves the search ability of the algorithm. In 12 test functions, RCWOA was compared with 6 other algorithms, demonstrating the feasibility and novelty of RCWOA. In 8 experiments of fundus image segmentation, RCWOA was compared with 9 other algorithms. The results showed that RCWOA had a Friedman test composite ranking of 1.3516, ranking at the forefront, and exhibited significantly improved segmentation quality.

Global Potential Energy Surfaces by Compressed-State Multistate Pair-Density Functional Theory for Hyperthermal Collisions in the O2+O2 System.

Interactions between oxygen molecules play an important role in atmospheric chemistry and hypersonic flow chemistry in atmospheric entries. Recently, high-quality ab initio potential energy surface (PES) of the quintet O4 was reported by Paukku et al. [J. Chem. Phys. 147, 034301 (2017)]. 10543 configurations were sampled and calculated at the level of MS-CASPT2/maug-cc-pVTZ with scaled external correlation. The PES was fitted to a many-body (MB) form with the many-body part described by the permutationally invariant polynomial approach (MB-PIP). In this work, the PIP-Neural Network (PIP-NN) and MB-PIP-NN methods were used to refit the PES based on the same data by Paukku et al. Three PESs were compared. It was found that the performances differ significantly in the O+O3 region as well as in the long-range region. Therefore, additional 1300 points were sampled, and the efficient compressed-state multistate pair-density functional theory (CMS-PDFT) was used to calculate the electronic structure of these 1300 points and 10543 points by Paukku et al. Then, a completely new quintet PES was fitted using the MB-PIP-NN method. Based on this PES, the quasi-classical trajectory (QCT) approach was used to reveal all possible reaction channels for hyperthermal O2-O2 collisions.

Decentralized Finance (DeFi) and Traditional Banking: A Convergence or Collision

Decentralized Finance (DeFi) and Traditional Banking: A Convergence or Collision

Safe and socially compliant robot navigation in crowds with fast-moving pedestrians via deep reinforcement learning

AbstractSafe and socially compliant navigation in a crowded environment is essential for social robots. Numerous research efforts have shown the advantages of deep reinforcement learning techniques in training efficient policies, while most of them ignore fast-moving pedestrians in the crowd. In this paper, we present a novel design of safety measure, named Risk-Area, considering collision theory and motion characteristics of different robots and humans. The geometry of Risk-Area is formed based on the real-time relative positions and velocities of the agents in the environment. Our approach perceives risk in the environment and encourages the robot to take safe and socially compliant navigation behaviors. The proposed method is verified with three existing well-known deep reinforcement learning models in densely populated environments. Experiment results demonstrate that our approach combined with the reinforcement learning techniques can efficiently perceive risk in the environment and navigate the robot with high safety in the crowds with fast-moving pedestrians.

Computation of corona generated ionic current environment of unipolar UHVDC transmission lines using gas bimolecular collision theory

Corona on UHVDC transmission line conductors initiates corona power loss and the inevitable ionic current flow environment at ground level. To limit this substantial flow of ionic current at ground levels, it is necessary to establish an appropriate line design configuration, including the diameter of the line conductor and the height level above the ground. It is a tedious and expensive process to establish this appropriate line design solely based on experimental findings. Hence, the computational based numerical analysis with the support of final experimental validation aids in arriving at a safe and optimal transmission line design dimension configuration. Thus, the ionic current flow environment of UHVDC transmission lines may be characterized by ionized space charge density, ionic current flow, and electrical field distribution. To estimate this ionic current flow, it is necessary to estimate the ionized space charge density in the ionization region, which incorporates the solution of the Poisson's equation. It is intricate to solve Poisson's equation with known boundary conditions: as ionization process depends on the atmospheric parameters also. Multiple computational techniques are developed to estimate the corona generated ionic current environment under the HVDC lines by waiving these atmospheric parameter effects and claims the lack of computational accuracy. In this paper, the unipolar corona equation, usually called Poisson's equation was solved by estimating the space charge ion density using the concept of gas bimolecular collision theory. The gas bimolecular collision theory inculcates the procedure to estimate the collisional reaction rate constant between the gas molecules at given atmospheric temperature and pressure parameters. Therefore, this paper developed a unique equation solution for the estimation of transition of the ionic current magnitudes at known atmospheric temperature and pressure ambient conditions. This unique equation solution prevents the multiple actual testing procedures offers to obtain safe and optimal line design dimension configurations. Multiple experimental studies are carried out up to ± 900 kV to compare the computed results in the outdoor and indoor climatic conditions at the ultra-high voltage laboratory, CPRI. Also, the computed results are compared with the results published in the literature. Based on the comparison of results, the developed computational technique exactly matches the experimental results and claims improved accuracy compared to other computational techniques.

METHODS FOR SOLVING PROBLEMS BASED ON THE LAWS OF CONSERVATION OF ENERGY AND MOMENTUM

This article is devoted to one such theory the theory of collision of bodies. The impact phenomenon is well described by a simple mathematical model. This article also discusses the issue of joint use of two conservation lows –energy and momentum –to solve various physical problems.

Absolute doubly differential angular sputtering yields for 20 keV Kr+ on polycrystalline Cu

We have measured the absolute doubly differential angular sputtering yield for 20 keV Kr+ impacting a polycrystalline Cu slab at an incidence angle of θi = 45° relative to the surface normal. Sputtered Cu atoms were captured using collectors mounted on a half dome above the sample, and the sputtering distribution was measured as a function of the sputtering polar, θs, and azimuthal, ϕs, angles. Absolute results of the sputtering yield were determined from the mass gain of each collector, the ion dose, and the solid angle subtended, after irradiation to a total fluence of ∼1 × 1018 ions/cm2. Our approach overcomes shortcomings of commonly used methods that only provide relative yields as a function of θs in the incidence plane (defined by the ion velocity and the surface normal). Our experimental results display an azimuthal variation that increases with increasing θs and is clearly discrepant with simulations using binary collision theory. We attribute the observed azimuthal anisotropy to ion-induced formation of micro- and nano-scale surface features that suppress the sputtering yield through shadowing and redeposition effects, neither of which are accounted for in the simulations. Our experimental results demonstrate the importance of doubly differential angular sputtering studies to probe ion sputtering processes at a fundamental level and to explore the effect of ion-beam-generated surface roughness.

Spotlight on Carcinosarcoma of the Ovary: A Scoping Review.

Ovarian carcinosarcoma, also referred as malignant mixed Mullerian tumour, is an uncommon, highly aggressive and malignant neoplasm which makes up 1 to 4% of all ovarian tumours. It is biphasic involving both malignant sarcomatous (mesenchymal) and carcinomatous (epithelial) cells. There are various subtypes such as serous and endometrioid. However, the mesenchymal part is sarcomatous. About 90% of cases of ovarian carcinosarcoma spread outside the ovary. The two most accepted theories of origin for carcinosarcoma of the ovary are the collision and conversion theories. A third theory is the combination theory. Prognosis remains poor even when still localised in the ovary. In the last few years, there has been no change in the survival rate. The median survival rate is lower than 2 years. Clinical features mainly include lower abdominal pain and a palpable abdominal mass. Ovarian carcinosarcoma remains poorly understood and understudied. Being a rare tumour, elaborate therapeutic consensus is not available for ovarian carcinosarcoma. The main treatment involves cytoreductive surgery and then chemotherapy. The type of chemotherapy, role of radiotherapy and novel therapies need to be further studied. The main objective of this article is to review the current literature on carcinosarcoma of the ovary.

Analysis and modeling for the dynamics of the nipper mechanism considering jaw’s impacts

The comber is very important in the spinning for high quality yarns, in which the nipper mechanism (NM) determines the quality of the yarn it combs. This paper is to connect topology and multi-body dynamics to reveal the principle of impact motion of the nipper mechanism. Firstly, the working process of the NM is analyzed and corresponding kinematic models of work sub-phases are derived. Subsequently, the transition from the work phase of the jaw closed to the opened is studied. The research results show that during the transformation process, the mechanism presented another work phase with multiple impacts, which is the main reason why the NM could not stably clamp the cotton clump and thus affect the quality of the yarn combed by the comber. According to the relative coordinate method, the dynamic model of the NM is set up. Combining the classical collision theory and the restitution coefficient equation, the acquisition of the impact impulse generated at the jaw and the subsequent motion of the mechanism are decided. Finally, the NM in the E62 comber is taken as an example to verify the correctness of the established dynamic model, and the influences of different input speeds, restitution coefficients, and stiffness coefficients of spring on the jaw’s impact are studied. This has certain theoretical value for improving the speed and efficiency of the comber.

Mental model of the influence of reactant properties on reaction rate

Reaction rate is still considered difficult by students because it contains abstract concepts and mathematical equations, so students' mental models are not complete. To connect the three levels of representation in the process of addressing chemical problems, learning has to employ mental models as a whole. Therefore, this study aims to obtain students' mental models regarding the influence of reactants properties on reaction rates. This research uses a qualitative descriptive method with the Mental Model Diagnostic Test-Interview About Event (MMDT-IAE) instrument. Based on the research results, there are two types of mental models, namely Partial Understanding (PU) and Partial Understanding with Certain Misconceptions (PU/SM). The effect of surface area on reaction rate, students 1, 2, 3, 4, 6, and 7 answered correctly but could not connect the three levels of representation, while student 5 could not explain the relationship between effective collisions and reaction rate. The influence of structure on reaction rates, students 1, 2, 3, 4, and 7 can answer structure, reactivity and collision theory, while student 5 cannot explain collision theory. Students 1, 4, and 7 can answer all the probing questions but cannot connect the three levels to the influence of ionization energy on the reaction rate. The conclusion of this research is that students' mental models regarding the influence of reactant properties are not complete and there are students who experience misconceptions. The implications of this research are as a basis for teachers to design appropriate learning strategies.