Influence Of Structural Changes Research Articles

Isomeric effects on the electron impact scattering for selected five membered heterocyclic ring molecules

Abstract We present electron scattering cross-sectional data for selected isomers of the five-membered ring molecules, specifically oxazole and isoxazole, thiazole and isothiazole, and imidazole and pyrazole. The ab-initio R-matrix method, incorporating static exchange polarization approximations, is employed for this calculation from energy range 0.1 eV to 20 eV. Three shape resonances are identified and characterized in each system, consisting of two π* and one σ* shape resonances. Notably, thiazole and isothiazole exhibit additional σ* resonance which is which is at a lower energy than other σ* resonance. The calculated resonance positions align well with available experimental as well as theoretical data. We also performed electronic structure calculations to aid in characterization of resonances. Comparison of the scattering cross-sectional data with their respective isomers reveal marginal differences in the magnitude of the elastic cross section particularly below 1 eV. This discrepancy may be attributed to variations in the long-range electronic dipole contribution to the electron-molecule interaction process. Further, to understand dependency of dipole moment on elastic cross section, we performed a fitting procedure for the elastic cross sections at 0.1 eV with square of the dipole moment of all the five membered ring molecules studied here. The fitting formula so obtained was used to estimate the cross section for other three five membered ring molecules: Furan, Thiophene and Pyrrole. Additionally, total ionization cross sections are computed using the binary-encounter-Bethe (BEB) model, demonstrating nearly identical results when compared with their isomers. Our findings offer insights into the influence of structural changes on the electron scattering data, providing guidance for other theoretical investigations.

Investigation of the Influence of Structural Changes in Aqueous Solutions of Phenol on Its Ability to Be Extracted by Fe3O4 Magnetic Nanoparticles

Investigation of the Influence of Structural Changes in Aqueous Solutions of Phenol on Its Ability to Be Extracted by Fe3O4 Magnetic Nanoparticles

Effect of Parameters of Ditch Geometry on the Uniformity of Water Filling in Ship Lock Chambers

The design of ditch structures in ship locks has an important influence on reducing water flow energy, improving the uniformity of water filling in lock chambers, and reducing the force acting on mooring ships. Existing studies on the mechanisms of flow fields and mooring conditions under the influence of geometric structural changes in ditches are insufficient, and research is limited by the complexity of the problem. Based on OpenFOAM v8, a numerical simulation of the flow structure in a lock chamber was carried out. Taking into account the ditch width, ditch depth, and sill height of the side wall as the research variables, the influence of structural changes in four single ditches on the uniformity of water filling in the lock chamber is systematically discussed. The results show that under a complex boundary constraint, the flow is diffuse in the ditch and the lock chamber, and the filling of the lock chamber is not uniform. The uniformity of water filling is closely related to the arrangement of the ditch geometry. Through the comprehensive analysis of multiple factors, some parameter thresholds were obtained to provide theoretical guidance for ditch design. It is hoped that through improved design, allowing an increase in the uniformity of water filling, the lock chamber will reach a relatively optimal state.

Optimization of Structural Parameters of Piezoelectric Injection Valve Based on Model Experiment and CFD Simulation

The miniaturization of electronic devices requires a decreasing quality of adhesive points. In order to obtain the minimum defect free adhesive point for injection, this paper uses a combination of Taguchi experiment and CFD method to systematically study the influence of structural changes in the needle nozzle on the mass size of the adhesive point of the piezoelectric injection valve. The results indicate that the structural changes of the needle nozzle have a significant impact on the quality of the sprayed adhesive point. For the five types of needle and nozzle structures studied, when the nozzle size is 0.05mm and the needle size is 1.0mm, the adhesive produced by the injection valve is the smallest, and the minimum adhesive mass is 13.3% of the original injection valve (APJ1500) injection mass. Through CFD simulation, it was found that due to the smaller nozzle diameter of the optimal parameter combination during the valve opening stage, and the higher reflux ratio of the nozzle combination during the needle lowering stage, it can produce smaller adhesive mass.

The influence of structural changes and defects on noise mitigation properties of the periodic structures based on coupled Helmholtz resonators

The work is dedicated to investigation of several ways for optimization of periodic structures based on coupled Helmholtz resonators. Such modifications as chirped lattices, arbitrary defects, and supercells, are explored. We analyze widening of stop-bands associated with the introduction of these structural changes and how they affect the corresponding noise mitigation properties. Utilizing numerical calculations we find optimal parameters of the considered structures and study the dependence of transmission coefficient on various geometric parameters of the system. As a main result, we demonstrate the merging of several stop-bands leading to ultra-broadband noise mitigation. The achieved enhancement is linked to the properties of the equivalent infinite structures and their eigenmodes.

A theoretical–experimental study of KSr2Nb(3-x)TaxO10 (x = 0,1,2) systems as photocatalysts

Understanding the influence of structural changes arising from electronic characteristics is a significant challenge in novel material development. The Nb(V) and Ta(V) cations are pertinent due to their similar ionic radii across various coordinations. Layered perovskites (KSr2Nb(3-x)TaxO10, where x = 0,1, and 2) were synthesized using the solid-state method. These compounds were characterized employing experimental techniques and subjected to photocatalytic testing in a model reaction. Density Functional Theory simulations were conducted, confirming experimental data accuracy and prediction reliability. Evaluation of intra and inter-octahedral distortion and charge carrier effective masses were correlated with experimental outcomes. Remarkably, substituting Nb with Ta increased photocatalytic activity, suggesting a promising avenue for tailoring material properties.

Influence of structural changes on gas transport properties of a cycled CaO/Ca(OH)2 powder bulk for thermochemical energy storage

Thermochemical energy storage using reversible gas-solid reactions has a great potential to evolve into a vital part of a future energy system. A major obstacle for technical application, however, is caused by insufficient gas transport within storage reactors leading to ineffective charging and discharging as well as lower storage densities. Although significant changes in the solid bulk structure are reported throughout the literature, the relevant material property – the bulk permeability – is rarely experimentally studied. In the presented study, the evolution of the gas permeability of a technical grade CaO/Ca(OH)2 powder bulk is studied experimentally. To this end, the pressure drop at ambient conditions is recorded before thermochemical cycling as well as after each dehydration respectively rehydration reaction. The pressure gradient and thereby the permeability is determined based on Darcy's law. The permeability of the fresh Ca(OH)2 bulk after compaction due to the gas flow is 1·10−13 m2. Due to restructuring during thermochemical cycling the permeability increases to 1.6…3.3·10−12 m2 for the cycled Ca(OH)2 bulk and 9.2·10−12 m2 to 2.4·10−11 m2 for the cycled CaO bulk. Further analysis of fresh and cycled samples shows a general increase in particle size and decrease in specific surface area as well as a reduction in reactivity due to agglomeration of the powder. Noticeable is the inhomogeneity of the cycled bulk with powder mixed with larger agglomerates at the top of the bulk and highly porous but seemingly homogeneous solid material at the bottom. Based on the experimental results, gas transport within the agglomerates is identified as a major limiting factor within thermochemical reactors. It is therefore proposed to consider cycled CaO/Ca(OH)2 bulks on a macro- and mesoscale (respectively bulk and agglomerate) simultaneously if transport properties – and their impact on effective reaction dynamics – are relevant.

Effect of Hydroxyl-Containing Fragments on the Structure and Properties of Membrane-Forming Polyamide-Imides.

The structural features and thermophysical and transport properties of dense nonporous membranes of the casting type from (co)polyamide-imides synthesized by the polycondensation of the diacid chloride of 2-(4-carboxyphenyl)-1,3-dioxoisoindoline-5-carboxylic acid and diamines 5,5'-methylene-bis (2-aminophenol) (DADHyDPhM) and 4,4'-methylenebis(benzeneamine) (DADPhM), taken in molar ratios of 7:3, 1:1, and 3:7, have been studied. The effect of hydroxyl-containing modifying fragments of dihydroxy diphenylmethane introduced in various amounts into the main polymer chain on the pervaporation properties of the formed films is discussed. It has been shown that the presence of the residual solvent N-methyl-2-pyrrolidone in the films not only has a plasticizing effect on the characteristics of film membranes but also promotes the preferential transmembrane transport of polar liquids, primarily methanol (permeation rate over 2 kg for a copolymer with a ratio of DADHyDPhM:DADPhM = 7:3). The removal of the residual solvent from the polymer film, both thermally (heating to 200 °C) and by displacement with another solvent as a result of sequential pervaporation, led to a significant decrease in the rate of transfer of polar liquids and a decrease in the selectivity of the membrane. However, the dehydrocyclization reaction resulted in more brittle films with low permeability to penetrants of different polarities. The results of our comprehensive study made it possible to assume the decisive influence of structural changes in membranes occurring in connection with the competitive formation of intra- and intermolecular hydrogen bonds.

MORPHOMETRIC CHARACTERISTICS OF THE MANDIBULAR CONDYLAR PROCESSES

Aim: to study the morphometric characteristics of the mandibular condylar processes to identify patterns and their classification. Materials and Methods: a study of 49 skeletonized and certified mandibular preparations was performed using a caliper and a depth gauge. During the study of the material, the forms and the main morphometric parameters of the condylar processes were determined and analyzed. Statistical data processing was carried out using the Microsoft Excel program. Results: The study of certified biological material yielded the main morphometric and morphofunctional parameters of the mandibular condylar processes. We revealed characteristic differences in the anatomical structures of the studied preparations. The main variants and types of combinations of forms of condylar processes were singled out: oval, hook-shaped, diamond-shaped, L-shaped. The lowest asymmetry index is characteristic of a combination of oval and diamond–shaped forms - 2.44%., and the highest asymmetry index is characteristic of diamond–shaped and L-shaped forms of condylar processes - 7.13%. Conclusion: The presented data can help practitioners to more accurately determine the target point for Gow-Gates anesthesia; to take into account the nature of the influence of structural changes in the joint on other elements of the dental apparatus, thus preventing functional diseases of the temporomandibular joint. The methodology of studying the main morphometric parameters on skeletonized preparations of the lower jaws can be adapted for the examination of living persons using diagnostic radiology.

Relationship between kidney ultrasound data and blood creatinine and urea levels in cats with autosomal dominant polycystic kidney disease

The results of studying the influence of structural changes in the kidneys on their filtration in cats with polycystic kidney disease are given. The study was conducted on 10 domestic cats, which were divided into two experimental groups based on the results of creatinine determination according to the IRIS (International Renal Interest Society) classification – 5 animals with moderate renal azotemia (group 1) and 5 animals with severe renal azotemia (group 2). Ultrasound examination of the kidneys of cats in both groups was performed using a Mindray device with a microconvection transducer with a frequency of 7.5–10 MHz in B-mode. Both kidneys were examined in each animal. Scanning was performed in the sagittal plane so that the kidney gate was visible. The length, width of the kidney, and thickness of the cortical layer, as well as the number of cysts and their diameter, were counted. The renal area (RA), cyst area (CA), and the ratio of cyst area to renal area (RA/Cyst) were calculated. According to the results of the study of serum creatinine and urea content, the animals were divided into two groups depending on the level of azotemia. 5 cats with stage III chronic renal failure (CRF), serum creatinine levels were 326.40 ± 23.59 μmol/l, and 5 animals with stage IV chronic renal failure serum creatinine – 887.00 ± 61.81 µmol/l, which is 2.7 times higher (P ≤ 0.001) than the creatinine level in cats with stage III CKD. The urea content in the serum was significantly increased compared to the norm and amounted to 22.82 ± 2.09 mol/l in cats with stage III CKD and 42.45 ± 1.05 mol/l in cats with stage IV CKD, which was 2.2 times higher (P ≤ 0.01) compared to stage III. In animals with polycystic kidney disease and stage IV chronic renal failure according to the results of ultrasound examination an increase in the length of the kidney by 6.5 mm (p≤0.001) and a thickening of the cortical layer by 0.8 mm (P ≤ 0.01) was revealed, compared to animals with polycystic kidney disease and stage III chronic renal failure. There was no correlation between the area of cysts in the kidneys and the level of creatinine in the blood serum of animals. Ultrasound signs of chronic renal failure in cats of stage III are enlargement of the kidney in the length of more than 51 mm and cortical thickness of more than 5.5 mm, of stage IV is an increase in kidney length of more than 59 mm and cortical thickness of more than 6.0 mm. According to the results of ultrasonography, the number of cysts or their area cannot be used to assess the degree of renal functional failure.

Study on aerodynamic characteristics and parameters of high-speed elevator car-counterweight intersection

When the high-speed elevator is running, the air in the hoistway is rapidly compressed and released to form the piston effect. Especially when the car and counterweight intersect, the piston effect makes the aerodynamic force of the car and counterweight change sharply, affecting the stability of elevator operation. In this study, a three-dimensional car counterweight intersection model is constructed, and a multi-region dynamic layered method is proposed to calculate the aerodynamic flow field in the whole moving process, the changes of aerodynamic drag force and aerodynamic lateral force of the car and the counterweight under different length ratio, blockage ratio and spacing are analyzed and simulated, and the influence of structural changes in the hoistway on the aerodynamic flow field is studied. Furthermore, the accuracy of the numerical results is verified by the real elevator test. Finally, the results show that when the car intersects the counterweight in the hoistway, the interaction between the car and the counterweight is enhanced, and the drag force coefficient and lateral force coefficient of the car suddenly change, and return to the normal state after the intersection, with the decrease of length ratio and spacing and the increase of blockage ratio, the sudden change degree of drag force also increases, and the sudden change of lateral force of the car is mainly affected by the car counterweight spacing, and increases with the decrease of spacing.

Correlation analysis between noise reduction function and biological structure of Acer truncatum crown

Taking Acer truncatum as the research object, this paper discusses the influence of structural changes on the noise reduction effect, and quantitatively measures and analyzes the biological structural characteristics and noise reduction effect. The conclusions are as follows: 1) structural changes, especially the changes of branches and leaves, have a significant impact on the noise reduction effect of the crown. The noise reduction effect of the complete crown is the best. With the thinning of branches and leaves, the noise reduction ability of the crown gradually decreases. The noise reduction ability of the complete crown >2/3 crown >1/4 crown >0 crown. 2) All the 17 biological structures have a very significant impact on the noise reduction effect of the crown. The light transmittance, porosity and branch density of the crown are the key structures that affect the noise reduction effect of the crown of Acer truncatum. The light transmittance and porosity of the facade are negatively correlated with the noise reduction effect, and the branch density is positively correlated with the noise reduction effect. The smaller the gap between branches and leaves in the crown and the denser the branches, the better the noise reduction effect of the crown.

Influence of Geometrical Parameters on the Optical Activity of Chiral Gold Nanorods

AbstractChiral metal nanoparticles (NPs) offer a powerful means of inducing and harnessing optical activity. However, due to the incomplete knowledge of the underlying growth mechanisms, there is still limited control over the achievable morphological detail and, consequently, over the resulting optical activity. Therefore, theoretical modeling is needed to guide experimental development toward optimizing the plasmonic chiroptical response. Toward filling this gap, herein an extensive parametric analysis is presented, via computer‐aided‐design (CAD) models and full‐wave electrodynamic simulations, which aims at systematically analyzing the influence of structural changes on the plasmonic circular dichroism (CD) spectra of rod‐shaped gold NPs comprising helical indentations on achiral nanorod cores. From this analysis, interesting patterns in the plasmon‐mediated resonant behavior are identified and cause–effect relationships are drawn that may serve as a go‐to recipe for the understanding and fabrication of these NPs and their applications, such as spectroscopic (bio)detection including CD spectral shifts and surface‐enhanced Raman optical activity.

Magneto-Thermal Coupling Simulation of Flowing Liquid Induction Heating through Static Mixer-Type Susceptors

As a new non-contact heating technology, induction heating technology has very broad application prospects in the field of fluid food heating. However, its application is inevitably affected by the heat concentration caused by uneven energy distribution. The uneven temperature distribution of the heating process will lead to the decrease in the quality of heating products. Therefore, based on the previous research, in order to improve the uniformity of heat distribution in the heating process, this study selected the susceptor with the greatest potential for efficient and the most uniform heating fluid to carry out the coupling simulation of electromagnetic heat transfer. The susceptor was simulated and optimized in three aspects: different power comparisons, the influence of structural change on temperature distribution uniformity, and the influence of physical property change of metal material on temperature distribution uniformity. The results show that the simulation results are in good agreement with the experimental results, and the error between the experimental and simulation values of the outlet temperature at Kelvin temperature is less than 0.18%. The change of geometric structure had a great influence on the uniformity of temperature distribution, and the uniformity of temperature distribution was inversely proportional to the conductivity. During the simulation, the temperature of the fluid heated by the susceptor was increased from 284.75 K to about 333K. The temperature distribution of the fluid at the outlet of the susceptor was uniform, and the temperature difference was about 1 K.

Synergistic effect of adjustable ejector structure and operating parameters in solar-driven ejector refrigeration system

The ejector has a substantial impact on the performance of the solar-driven ejector refrigeration system. This work designs an adjustable ejector without disassembly and performs numerical modeling of the geometric model to enhance the ejector capacity to adapt to various operating conditions; the simulations dependability was also validated using experimental evidence. The findings indicate that within the given operating conditions, the adjustable ejector efficiency increased by an average of 82.4 %; the COP of the system increased by an average of 72.8 %. It is also found that the adjustable ejector has a saturation region, where the ejector performance rapidly declines as the nozzle exit position increases. Under the given operating conditions, the functional relationship between the optimal area ratio and nozzle exit position is obtained. By defining the operating condition coefficient (Γ), the function of the Γ and optimal area ratio is obtained, which provides the adjustable ejector control logic. From the energy perspective, the influence of structural changes on the vortex near the premixing chamber wall is analyzed, and the basic internal reasons for how structural alterations affect the ejector performance are initially revealed.

Influence of coal structure change caused by different pretreatment methods on Shengli lignite pyrolysis

Coal pyrolysis is one of the methods of clean and efficient utilization of coal. Coal has a complex structure, which has an important influence on its pyrolysis characteristics. In order to further explore the structure–activity relationship between the structure and pyrolysis characteristics of coal, the structure of coal can be artificially changed to investigate the influence of structural changes on its pyrolysis characteristics. In this study, hydrothermal pretreatment (HTP) and solvent swelling pretreatment (SSP) were used to artificially change the structure of Shengli (SL) lignite. The influence of each pretreatment on the physicochemical structure was analysed by Fourier-transform infrared (FT-IR), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The evolution of functional groups and the pyrolysis characteristics of the SL/pretreated coal were investigated by using an in-situ FT-IR device and a fluidised bed reactor, respectively. The results showed: HTP could remove some oxygen-containing functional groups and aliphatic side chains, hydrolyze ether bonds and generate phenolic hydroxyl groups, thus destroying the cross-linking structure, promote the release of aromatic CC, the yield of pyrolysis tar increased from 9.4% to 10.6%, and the content of light tar increases from 43.1% to 49.1%. SSP mainly weakening the cross-linking structure by destroying hydrogen bonds and dissolving part of oxygen-containing functional groups, which reduces the pyrolysis activation energy of oxygen-containing functional groups and aliphatic groups, promotes the generation of tar. Accordingly, the yield of tar increases from 9.4% to 11.1%, and the content of light tar increases from 43.1 % to 49.8%. In particular, this research work reveals the structure–activity relationship between the structural changes of coal and the pyrolysis characteristics, which provides a theoretical basis for the directional pyrolysis of lignite.

Tuning the Force, Speed, and Efficiency of an Autonomous Chemically Fueled Information Ratchet.

Autonomous chemically fueled molecular machines that function through information ratchet mechanisms underpin the nonequilibrium processes that sustain life. These biomolecular motors have evolved to be well-suited to the tasks they perform. Synthetic systems that function through similar mechanisms have recently been developed, and their minimalist structures enable the influence of structural changes on machine performance to be assessed. Here, we probe the effect of changes in the fuel and barrier-forming species on the nonequilibrium operation of a carbodiimide-fueled rotaxane-based information ratchet. We examine the machine’s ability to catalyze the fuel-to-waste reaction and harness energy from it to drive directional displacement of the macrocycle. These characteristics are intrinsically linked to the speed, force, power, and efficiency of the ratchet output. We find that, just as for biomolecular motors and macroscopic machinery, optimization of one feature (such as speed) can compromise other features (such as the force that can be generated by the ratchet). Balancing speed, power, efficiency, and directionality will likely prove important when developing artificial molecular motors for particular applications.

Healing behavior of thermo-oxygen aged asphalt based on molecular dynamics simulations

• Self-healing abilities of aged and recycled asphalt were experimentally studied. • Molecular dynamics simulations were also performed. • The density and glass transition temperature were used for model verification. • Diffusion coefficient showed good positive correlation with the healing index. To understand the change law and causes of the self-healing ability of asphalt during aging, a thin-film oven test was used to simulate different aging degrees of asphalt, and the “damage-healing-damage” test was performed using a dynamic shear rheometer. The influence of structural changes in aged and recycled asphalt on the healing index was analyzed by Fourier transform infrared spectroscopy and differential scanning calorimetry. Molecular Studio was used to establish five asphalt healing models. The asphalt healing index decreased with the degree of aging, and the regenerant improved the healing performance. The types of asphalt functional groups were similar, but the sulfoxide group content and the glass transition temperature increased with the aging degree. The asphalt models were verified by the density and glass transition temperature. The two parameters tended to stabilize after 20 ps of healing, and the radial distribution function curves were similar. The mean square displacement and diffusion coefficient of the asphalt model increased with increasing healing temperature and decreased with increasing aging degree. There was a positive correlation between the diffusion coefficient and healing index. Molecular dynamics simulations can help scholars better understand asphalt’s healing process and movement law.

Nanoscale strain–stress mapping for a thermoplastic elastomer revealed using a combination of in situ atomic force microscopy nanomechanics and Delaunay triangulation

AbstractStyrene block copolymer‐type thermoplastic elastomer (TPE) has a nanoscale phase‐separated structure and undergoes topological changes in response to external stimuli. A typical example is the macroscopic stress relaxation in TPEs while maintaining the elongated state. To understand the influence of structural changes on the mechanical properties of TPEs, in this work, we evaluate a styrene‐ethylene‐butylene‐styrene‐type TPE using an in situ atomic force microscopy (AFM)‐based nanomechanical approach while maintaining 50% strain. According to AFM deformation and modulus maps of the same area at different relaxation times, it is found that the hard polystyrene domain splits in the early stage of relaxation, resulting in a constant rise in the number. At the same time, the modulus of the soft poly(ethylene‐butylene) matrix continues to decrease. Both the domain number and matrix modulus stabilize in the late stage of the relaxation. Further finite element analysis explains the above phenomenon. The distribution of stresses and strains under the material microscopically evolves toward homogenization with relaxation time. The internal stress network achieves an elastic behavior after sufficient relaxation at the expense of hard‐domain splitting.

Tribological Behavior of Friction Materials of a Disk-Brake Pad Braking System Affected by Structural Changes-A Review.

For road safety, braking system performance has become a very important requirement for car vehicle manufacturers and passengers. To this end, vehicle designers must understand the characteristics of tribological behavior and the causes of their variation in properties. This paper analyzes the tribological behavior (at friction and wear) of the most recent material couples of the braking disk-pad system affected by their structural change through the implications on the braking system stability, reliability and suitable characterizations. Obtaining information to design a very efficient braking system and assessing the influence of the material’s structural changes on its stability has become a necessity. This has been made possible by using several methods of testing a brake disk-pad couple on various devices intended for this purpose. The materials of the contact surface disk-brake pad with their tribological performance (friction, wear), especially the friction coefficient, present particular importance. Also, system components’ reliability, heat transfer and the noise and vibration of the brake disk-pad couple are vital to the correct operation of the braking system and should be given special attention. The test results obtained define the friction patterns and the influence of structural changes and other environmental factors that can be used in computer analysis.