Cross Section Research Articles

Machine Learning Framework for Conotoxin Class and Molecular Target Prediction

Conotoxins are small and highly potent neurotoxic peptides derived from the venom of marine cone snails which have captured the interest of the scientific community due to their pharmacological potential. These toxins display significant sequence and structure diversity, which results in a wide range of specificities for several different ion channels and receptors. Despite the recognized importance of these compounds, our ability to determine their binding targets and toxicities remains a significant challenge. Predicting the target receptors of conotoxins, based solely on their amino acid sequence, remains a challenge due to the intricate relationships between structure, function, target specificity, and the significant conformational heterogeneity observed in conotoxins with the same primary sequence. We have previously demonstrated that the inclusion of post-translational modifications, collisional cross sections values, and other structural features, when added to the standard primary sequence features, improves the prediction accuracy of conotoxins against non-toxic and other toxic peptides across varied datasets and several different commonly used machine learning classifiers. Here, we present the effects of these features on conotoxin class and molecular target predictions, in particular, predicting conotoxins that bind to nicotinic acetylcholine receptors (nAChRs). We also demonstrate the use of the Synthetic Minority Oversampling Technique (SMOTE)-Tomek in balancing the datasets while simultaneously making the different classes more distinct by reducing the number of ambiguous samples which nearly overlap between the classes. In predicting the alpha, mu, and omega conotoxin classes, the SMOTE-Tomek PCA PLR model, using the combination of the SS and P feature sets establishes the best performance with an overall accuracy (OA) of 95.95%, with an average accuracy (AA) of 93.04%, and an f1 score of 0.959. Using this model, we obtained sensitivities of 98.98%, 89.66%, and 90.48% when predicting alpha, mu, and omega conotoxin classes, respectively. Similarly, in predicting conotoxins that bind to nAChRs, the SMOTE-Tomek PCA SVM model, which used the collisional cross sections (CCSs) and the P feature sets, demonstrated the highest performance with 91.3% OA, 91.32% AA, and an f1 score of 0.9131. The sensitivity when predicting conotoxins that bind to nAChRs is 91.46% with a 91.18% sensitivity when predicting conotoxins that do not bind to nAChRs.

Excitation of Helium by Proton and Antiproton Impact

The electron transitions in atoms caused by charged particle impact are benchmarks for the study of electron dynamics. In the present paper we focus on the excitation of helium by proton and antiproton impact. We perform both ab initio and perturbational calculations, revealing the importance of electron correlations and higher-order effects. The influence of the projectile charge sign on the excitation cross section is also studied.

The Influence of the Ratio of Circumference to Cross-Sectional Area of Tensile Bars on the Fatigue Life of Additive Manufactured AISI 316L Steel

The static and dynamic loading capacities of components depend on the stress level to which the material is exposed. The fatigue behavior of materials manufactured using additive technology is accompanied by a pronounced scatter between the number of cycles at the same stress level, which is significantly greater than the scatter from a material with the same chemical composition, e.g., AISI 316L, but produced by rolling or forging. An important reason lies in the fact that fatigue cracks are initiated almost always below the material surface of the loaded specimen. Thus, in the article, assuming that a crack will always initiate below the surface, we analyzed the fatigue behavior of specimens with the same bearing cross section but with a different number of bearing rods. With a larger number of rods, the circumference around the supporting part of the rods was 1.73 times larger. Thus, experimental fatigue of specimens with different sizes showed that the dynamic loading capacity of components with a smaller number of bars is significantly greater and can be monitored by individual stress levels. Although there are no significant differences in loading capacity under static and low-cycle loading of materials manufactured with additive technologies, in high-cycle fatigue it has been shown that the ratio between the circumference and the loading cross section of tensile-loaded rods plays an important role in the lifetime. This finding is important for setting a strategy for manufacturing components with additive technologies. It shows that a better dynamic loading capacity can be obtained with a larger loading cross section.

Impact of Serum Folate and Vitamin B12 on Mental Health in Patient Admitted at Razi Psychiatric Hospital

Vitamin B12 (cobalamin) is one of the essential vitamins that affect various systems in the body, including the central nervous system and plays an important role in the metabolism of the nervous system, although its exact role under pathological conditions is not fully understood. The present study aimed to assessing vitamin B12 & serum folate in patient admitted at Razi psychiatric hospital. A cross section study subjects were inpatients with psychiatric disorder, patients from 21 to 60 years old. In this group of 40 psychiatric patients, there is no evidence of clinically relevant changes in serum vitamin B12 and folate level. Vitamin B12 deficiency can occur despite “normal” serum cobalamin levels; therefore, measuring homocysteine and methyl malonic acid can decrease false-negative findings.

Three-dimensional elastic Rayleigh–Taylor instability at the cylindrical interface

This paper presents a linear analysis of elastic Rayleigh–Taylor instability at both cylindrical column and cylindrical shell interfaces. By considering the rotational part of the disturbance flow field, an exact solution is derived, revealing that the most unstable mode is two-dimensional in the cross section. As the column radius decreases, the maximum growth rate increases, while the corresponding azimuthal wave number decreases incrementally until it reaches 1. Thinning the cylindrical shell is found to be a destabilizing effect, leading to an increase in both the cutoff wave number and the most unstable azimuthal wave number. The maximum growth rate usually increases as the shell becomes thinner, except in cases with small radii where feedthrough effects occur. For thin shells with small radii, the cutoff axial wave number is determined by the radius rather than the shell thickness. Comparisons between the growth rates derived from the potential flow theory and the exact solution show significant discrepancies in cylindrical shells, mainly due to substantial deviations in the cutoff wave number.

Integration of ML methods with CR model-based optical diagnostic for the estimation of electron temperature in Ga laser produced plasma

Accelerated diagnostic of plasma plays a significant role in controlling and optimizing plasma-mediated processing, particularly for plasma with higher temporal and spatial gradients, such as laser produced plasma (LPP). In the present work, two advanced machine learning (ML) algorithms, random forest regression, and gradient boosting regression are integrated with noninvasive collisional radiative (CR) model-based optical diagnostics to facilitate accurate diagnostics. A comprehensive fine-structure resolved CR model framework is developed by incorporating our consistent cross section data obtained from the Relativistic Distorted Wave method [Suresh et al., “Fully relativistic distorted wave calculations of electron impact excitation of gallium atom: Cross sections relevant for plasma kinetic modelling,” Spectrochim. Acta B: At. Spectrosc. 213, 106860 (2024)]. An extensive dataset of CR model simulated intensities is created to train and test the ML methods. The present CR model is applied to characterize the Gallium LPP coupling with the optical emission spectroscopic measurements of Guo et al. [“Time-resolved spectroscopy analysis of Ga atom in laser induced plasma,” Laser Phys. 19, 1832–1837 (2009)] at different delay times. Further, a detailed correlation study of the line intensity ratios is performed to observe the qualitative behavior of the plasma parameters. The electron temperature results obtained from the CR model, ML, and line ratio methods were compared and found to be in excellent agreement. Overall, the present study demonstrates diagnostic approaches that can benefit the LPP community significantly by providing a rapid understanding of the plasma behavior across various operating conditions.

Heat transfer evaluation of return-flow impingement cooling considering inclined sidewall and conical return hole

Impingement cooling techniques are extensively utilized on the turbine blade leading edge to mitigate thermal load. This study is an extend of an anti-crossflow return-flow impingement cooling scheme. In this study, the effects of inclined sidewalls and return holes are numerically studied with jet Reynolds number varying from 5,000 to 15,000. Three sidewall schemes (vertical, inward inclined, and outward inclined) and two return hole shapes (constant cross section and conical cross section) are investigated and compared. Numerical results show that by inclining the sidewalls, the interaction and scrape effects from return flow on the sidewalls are changed, causing heat transfer performance and pressure loss vary. To be specific, as the sidewalls are inclined inwards/outwards, the heat transfer is enhanced/weakened accordingly, making a maximum increase by 12.9% and maximum decrease by 14.3% compared to the origin design. The introduction of conical return holes contributes to improving upwards velocity of return flow and subsequently enhancing scraping effects on sidewalls. For case with vertical sidewalls, inward-inclined sidewalls, and outward-inclined sidewalls, the area-averaged Nusselt number is maximum increased by 47.2%, 61.9% and 25.7% with the application of conical return holes.

Giant Quadrupole Resonances within neutron-induced α-particle emission?

The particular conditions for the recent measurement of 91Zr(n,α)88Sr reaction cross sections at incident energies below 5.3 MeV [Phys. Rev. C 106, 064602 (2022)] as well as a previous detailed analysis of other reaction channels involving neutrons incident on 91Zr, using a consistent set of model parameters, have two main advantages. First, the close agreement between the calculated and experimentally obtained data for the incident energy associated mainly with the ground-state activation provides strong support for the α-particle optical potential involved in this analysis. Second, a further underestimation of the cross section is observed around the energy corresponding to the isoscalar giant quadrupole resonance (ISGQR), beyond any model parameter uncertainty. This underestimation is consistent with previous observations of ISGQR-like α-particle decay of excited nuclei for neutron-induced reactions in the mass range 54≤A≤98. To phenomenologically identify the ISGQR-like behavior, a comparison is made between their strengths and the ISGQR strengths measured through the (γ,α) reaction and inelastic scattering of 3He and α-particles. Additionally, an isotope effect, possibly related to the decrease in Q-value with the target-nuclei asymmetry parameter, supports the observation of a low energy-weighted sum rule (EWSR) fraction for the ISGQR-like strength function in the excited nucleus 92Zr.

Correction to: Feasibility study of the photonuclear reaction cross section of medical radioisotopes using a laser Compton scattering gamma source

Correction to: Feasibility study of the photonuclear reaction cross section of medical radioisotopes using a laser Compton scattering gamma source

Seismic performance and calculation method for plastic hinge length of RC pier reinforced with UHPC

Piers are highly vulnerable load-bearing components, and their seismic performance determines the integral seismic resistance of bridges to a certain degree. They play crucial roles in evacuation during earthquakes and post-earthquake rescue. The manner in which piers meet the seismic performance requirements after reinforcement has become a popular research topic. In this study, ultra-high-performance concrete (UHPC) and HTRB600E high-tensile reinforcements were used to expand the cross section of a cast-in-place square pier with severe bending damage. The earthquake-resistant behaviour indicators of the pier were compared and analysed by conducting pseudo-static tests on a reinforced concrete pier before and after reinforcement. These indicators included the hysteretic curve, skeleton curve, energy dissipation curve, rigidity degradation, residual displacement, and pier body curvature. Based on the results of the seismic reinforcement quasi-static tests, a finite element model (FEM) of the bridge pier was constructed using the ABAQUS software, and the accuracy of the FEM was averaged. The impact of the reinforcement layer height, thickness, longitudinal strength and axial compression ratio on the equivalent plastic-hinge length of the reinforced pier was analysed, and the formula for the equivalent plastic-hinge length of the reinforced pier was obtained based on multiple linear regression fitting. The analysis results demonstrated that the broadened section method, utilising UHPC and high-tensile reinforcement, significantly enhanced the flexural capacity, energy dissipation, and first rigidity of the bridge pier. The earthquake-resistant behaviour of pier was effectively restored and improved, and the seismic reinforcement effect was significant. The equivalent plastic hinge length of the pier after reinforcement is proportional to the height of the reinforcement layer, the thickness of the reinforcement layer, the strength of the longitudinal reinforcement, and inversely proportional to the axial compression ratio.

A Dynamic Volumetric Heat Source Model for Laser Additive Manufacturing

Melt pool scale models of laser powder bed fusion (LPBF) offer insights into the process-structure-property relationships in additive manufacturing (AM). These models often neglect physical phenomena such as vapor cavity formation and fluid mechanics to reduce computational demands. Instead, volumetric heat source models are used to represent the effects that these phenomena have on the predicted melt pool dimensions. Generally, the dimensions and effective absorption of the volumetric heat source are calibrated to reproduce melt pool dimensions observed in metallographic cross sections taken from single-track experiments on bare plate. However, the transient nature of LPBF often deviates the melt pool dimensions from the assumed steady-state conditions of single-track experiments, motivating the need for a volumetric heat source model that more generally considers the dynamic relationship between melt pool shape and laser-material interactions. Here, we introduce a two-parameter volumetric heat source model that integrates several existing models into a generalized mathematical expression, providing independent control over the radial heat distribution via the parameter k and the volumetric shape of the heat source via the parameter m. This parameterization enables the calibration of melt pool shape predictions through simultaneous adjustment of these parameters, while keeping the radial heat source dimensions consistent with the experimental spot size (D4σ) and constraining the heat source depth and absorption to physically derived expressions for cavities. Consequently, the proposed volumetric heat source model adapts to changes in the local melt pool conditions due to scanning strategy and part geometry by dynamically adjusting the heat source depth and absorption. We demonstrate the capabilities of the proposed model through comparisons with a collection of experiments from the Additive Manufacturing Benchmark (AMBench).

Acoustic Boundary Output Feedback Stabilization of Dynamic $n-\tau$ Model Flame via Duct With Variable Cross Section

Acoustic Boundary Output Feedback Stabilization of Dynamic $n-\tau$ Model Flame via Duct With Variable Cross Section

Construction of cobalt zinc metal-organic frameworks derived Co/CoO/C composites toward broadband and high-efficiency electromagnetic wave absorption

The fabrication of novel carbon-based electromagnetic wave (EMW) absorbers with broad absorption bandwidth, strong absorption strength, low filler loading ratio and thin matching thickness remains a challenging task. Metal-organic frameworks (MOFs) are widely recognized as ideal self-sacrificial templates for the construction of carbon-based EMW absorbers. In this work, bimetallic CoZn-MOFs derived Co/CoO/C composites were prepared by combining magnetic stirring with subsequent pyrolysis treatment. The results showed that the morphology of carbon skeletons evolved from an irregular agglomerate to a uniform hexagonal star shape and then to an agglomerate again by reducing the molar ratio of Co2+ to Zn2+. Remarkably, excellent EMW absorption capacity in the Ku-band was achieved through carefully regulating the molar ratio of Co2+ to Zn2+. When the filling ratio was 20wt.%, the prepared Co/CoO/C composite exhibited the best EMW absorption performance with the minimum reflection loss of -64 dB at a thickness of 1.79mm and the maximum effective absorption bandwidth of 6GHz at a thickness of 2.14mm. Furthermore, the radar cross section in the far-field was simulated by computer simulation technique. In addition, the possible EMW attenuation mechanism was proposed. Therefore, the results of this paper could be helpful for developing carbon-based magnetic composites derived from MOFs as broadband and high-efficiency EMW absorbers.

An experimental and numerical study on the behavior of finite-length column vortex

This paper explores experimental and numerical investigation of the spatiotemporal dynamics of a finite-length vortex column in three dimensions using particle image velocimetry and large eddy simulation. The research examines the combined impact of bending, buckling, and core-splitting on a finite-length vortex column. More precisely, the work centers on the fundamental motions, evolutions in flow along the axis, how the shape of the vortex core changes over time, the instability caused by the long waves on the vortex column, and the division of the vortex core. A novel prototype is developed that utilizes piston-driven inflow and produces a vortex column through the principles of flow separation and Biot–Savart induction, which is studied for predicting an ex situ cyclonic line vortex. The present study discusses the complete three-dimensional overview of the same columnar vortex. The meridional swirl and the axial transport of vorticity deform the shape of the core cross sections in different lengths of the column. The jump in the axial velocity at the core boundary allows for the occurrence of bending instabilities with a left-handed helical structure. These instabilities have a long wavelength, similar to the length of the vortex column, and belong to the m = +1 mode. The vortex column experiences a non-uniform curvature and torsion caused by the intricate shape of the laboratory model and varying flow speeds at different heights of the vortex column. The results offer valuable insights into the role of inertia, Coriolis, and viscous forces on the dynamics of the vortex column.

Promoted cutting and energy transition efficiency by an asymmetric cutter

Laboratory and numerical tests were performed to understand the rock breakage mechanism of a CCS (constant cross section) cutter and an asymmetric cutter. The laboratory and numerical tests consistently show that the asymmetric cutter frequently generates larger breakage areas and consumes less indentation energy than the CCS cutter, but there is a defect spacing of 70 mm. Thus, the asymmetric cutter frequently has a higher cutting efficiency than the CCS cutter. In addition, the numerical tests reveal that the CCS cutter first generates a plastic zone and subsequently forms cracks to connect with the defect tips. In this process, a large proportion of the energy is wasted in the particle friction in the plastic zone. However, the asymmetric cutter tends to form much smaller plastic zones, which makes it difficult to generate particle friction. Only a small amount of friction energy is consumed in the later crack propagation process. Thus, the asymmetric cutter has a higher energy transition efficiency than the CCS cutter.

Production of neutron-rich nuclei in the vicinity of 78Ni: Fragmentation reactions of unstable 81Ga and 82Ge beams

The fragmentation reactions of neutron-rich unstable nuclei 81Ga and 82Ge at 250 MeV/nucleon have been studied in order to search the optimal mean for the production of very neutron-rich nuclei in the vicinity of 78Ni. The newly measured cross sections were compared with various calculations, showing a good agreement with EPAX3.01. The present work provides experimental insights into the two-step scheme—fragmentation following fission—as a method to produce very neutron-rich nuclei through a combination of ISOL and fragmentation of post-accelerated beams of unstable nuclei. Our results enable an evaluation of the potential of the two-step scheme in the production of very neutron-rich nuclei for the 78Ni region. The two-step scheme using fragmentation of a post-accelerated 81Ga beam could be an option to produce neutron-rich nuclei around 78Ni when the 81Ga beam intensity reaches 1.0×108 pps, compared to the one-step scheme with fission of 238U.

A State-Space Method for Vibration of Double-Beam Systems with Variable Cross Sections

A State-Space Method for Vibration of Double-Beam Systems with Variable Cross Sections

Performance and mechanism of the structure formation and physical-mechanical properties of concrete by modification with nanodiamonds

Nanomodifying additives in the building materials production is a relevant and widely studied topic in current building materials science. Nanodiamonds are used in various fields of science and technology. However, they were not used as a modifying additive in the production of building composite materials. The purpose of this study is to investigate the mechanism of interaction of chemically pure cavitation synthesis nanodiamonds (КНА-НС) with cement concrete on the structure formation and mechanical properties of fresh and hardened concrete. These KHA-HC nanodiamonds are carbon sp3 hybridized nanoparticles with a diamond-like structure and a particle size in a cross section of not more than 3nm, shaped close to spherical and a clear mono modal distribution throughout the entire fractional composition, with a maximum of 1nm to 3nm. During the research, the initial components were selected, the compatibility of these components was checked, including the formation of test samples, the properties of fresh concrete, the density of hardened concrete, compressive and flexural strength at various ages of hardening (2, 7, 14 and 28 days) were studied using standard methods, and X-ray diffraction and scanning electron microscopy of concrete were also carried out. It has been established that the addition of KHA-HC accelerates the process of concrete strength gain. The greatest effect was recorded for concrete aged 2 days. With an optimal KHA-HC content of 0.4%, the increases in compressive and flexural strength were 28.6% and 26.1%, respectively. The addition of KHA-HC in all considered ranges from 0.1% to 1.0% has a positive effect on the strength properties of concrete. The most effective dosage is 0.4%. The increases in compressive and flexural strength of concrete at an age of 28 days were 15.1% and 15.7%, respectively. Nanomodification of concrete with the KHA-HC additive does not affect the phase composition of concrete. The effect of “self-reinforcement of cement matrix” put forward in this study is confirmed by images of the microstructure of the cement matrix with a large accumulation of calcium hydrosilicate zones.

Enhanced microwave absorption using multiple heterostructures derived from in-situ grown Sn-metal-organic framework on La-doped Fe3O4

As a representative magnetic oxide absorber, Fe3O4 has attracted considerable research attention owing to its remarkable magnetic saturation strength as well as semiconducting properties. Doping Fe3O4 with La3+ leads to 3d-4f magnetic coupling and ion distribution changes due to the unique electron configuration and large ionic radius of La3+, thereby greatly enhancing the magnetic performance. However, high density, low dielectric loss, and low permeability at high frequencies inhibit the electromagnetic wave absorption (EMWA) performance of ferrites. In this study, stick-shaped Sn metal-organic framework (MOF) is in-situ grown on La3+-doped Fe3O4 using a surfactant. After high-temperature annealing, the SnO2/porous carbon composites derived from Sn-MOF wrap the ferrite, forming a core-shell heterostructure, which not only prevents oxidation but also enhances the EMWA performance. Among the prepared LaxFe3-xO4/SnO2/C (LFSC) samples, LFSC-2 (with LaxFe3-xO4 to Sn-MOF ratio of 1:2) exhibits strong absorption performance with a minimum reflection loss (RLmin) of −44.1 dB. Furthermore, the gradient metamaterial based on LFSC-3 shows ultra-broadband EMWA with an effective absorption bandwidth (RLmin ≤ −10 dB) of 13.17 GHz. In addition, the LFSC-2 sample demonstrates excellent radar stealth capability in the radar cross section (RCS) far-field response, achieving an RCS reduction value of 20.4 dB·m2.

Manufacturing of Thermoset Polyimide Composites by Laser Sintering

Selective Laser Sintering (SLS) is an additive manufacturing technique that builds 3D models layer by layer using a laser to selectively melt cross sections in powdered polymeric materials, following sequential slices of the computer-aided design (CAD) model. SLS generally uses thermoplastic polymeric powders such as polyamides. The resultant 3D-printed objects are often weaker in their strength compared to traditionally processed materials, due to their higher porosity. This paper described the process development of using melt-processable imide oligomers terminated with reactive 4-phenylethynylphthalic anhydride (4-PEPA) to conduct laser sintering (LS). The first successful 3D-printing of high temperature RTM370 thermoset polyimide carbon fiber composite was further post-cured to promote additional crosslinking for achieving higher temperature (Tg = 370°C) capability. Another novel imide oligomer, RTM385-SLS, formulated with a complex melt viscosity [h*] of ~104-105 poise is also suitable for LS. RTM385-SLS resin powder was mixed with 20-25% of hexagonal boron nitride (h-BN) and subjected to LS to print out “Green” specimens which could be further post-cured to afford a thermally conductive but electrically insulating composites with high Tg of 385°C. The cured composite specimens were then subjected to mechanical testing, thermal conductivity and porosity evaluation as well as SEM characterization.