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Abstract In the present study, the regime of motion of fullerene molecules on graphene substrate in a specific temperature range is investigated. The potential energy of fullerene molecules is analyzed using classical molecular dynamics methods. Fullerene molecules C36, C50, C60, C76, C80, and C90 are selected due to spherical shapes of different sizes and good motion performance in previous studies. Analysis of the motion regime at different temperatures is one of the main objectives of this study. To achieve this aim, the translational and rotational movements of fullerene molecules are studied independently. In the first step of the investigation, Lennard-Jone's potential energy of fullerene molecules is calculated. Subsequently, the motion regime of different fullerenes is classified based on their displacement and diffusion coefficient. Findings indicate C60 is not appropriate in all conditions. However, C90 and C76 molecules are found to be appropriate candidates in most cases in different conditions. As far as a straight-line movement is considered, the deviation of fullerene molecules is compared by their angular velocities. Although C60 has a lower angular velocity due to its symmetrical shape, it may not move well due to its low diffusion coefficient. Overall, our study helps to understand the performance of different fullerene molecules on graphene substrate and find their possible applications, especially as wheels in nanomachine or nanocarrier structures.

In this study, a novel method, Tubular Channel Angular Pressing-Extrusion (TCAPE), is introduced for manufacturing ultrafine microtubes. This method, integrating Tubular Channel Angular Pressing (TCAP) and microtube extrusion (MTE) processes, reduces the number of stages in the fabrication of ultrafine microtubes while achieving favorable mechanical properties. In the TCAPE process, the tube undergoes Severe Plastic Deformation (SPD) in the shaping region and is subsequently shaped into the desired geometric dimensions through the extrusion process at the end. To investigate the effect of the number of SPD passes on the microstructure and mechanical properties of the produced microtubes, one-pass and two-pass SPD were applied. Metallography, XRD testing, tensile testing, and hardness measurement were employed for analysis. For a one-pass SPD, the sample was processed only through the TCAPE process (TCAP + MTE), while for a two-pass SPD, the sample underwent the TCAP process first and then underwent TCAPE for the second processing step (2TCAP + MTE). Tensile test results indicate an increase in Ultimate Tensile Strength (UTS) from the initial value of 73 MPa–103.1 MPa and 148 MPa, and elongation altered from the initial value of 10 to 7.1 and 17.5 after two-pass SPD. Metallography results show a reduction in grain size from the initial value of 160 μm to 15 μm and 3 μm after two-pass SPD. The TCAPE process, due to applying higher strain (1.955) compared to the TCAP process (1.64), exhibits better performance in refining the microstructure and improving mechanical properties. The hardness and ultimate strength of the TCAPE-processed sample are 13.33% and 13.5% higher than those of the TCAP-processed sample, respectively.

In this study, the Cyclic Contraction-Expansion Extrusion (CCEE) process, a novel severe plastic deformation (SPD) technique, is applied to the AZ91 magnesium alloy to enhance its mechanical properties through microstructural refinement. The CCEE method combines cyclic expansion extrusion (CEE) and cyclic extrusion compression (CEC), integrating their advantages while overcoming drawbacks. The CCEE process is capable of inducing substantial plastic strain (3.38) within a single processing cycle, eliminating the need for secondary punches or a synchronized backpressure system. The process is conducted at a temperature of 300 °C, resulting in a bimodal microstructure through the dynamic recrystallization (DRX) mechanism. This microstructure consists of refined equiaxed α-Mg grains with an average size of 2.8 μm, surrounded by a network of newly nucleated α-Mg grains and Mg17Al12 particles with an average size of 500 nm in the two-pass processed sample. Results obtained from the tensile test technique indicate a significant enhancement in the ultimate tensile strength (UTS) of the AZ91 alloy, increasing from 139 MPa to 276 MPa and 290 MPa, and a notable improvement in elongation, increasing from 4% to 8% and 12% after two passes of the CCEE process. Macro-texture X-Ray diffraction (XRD) measurements reveal the formation of a pyramidal deformation texture in the one-pass sample, contributing to the UTS improvement. This texture weakens during the second pass, leading to an increase in elongation. Furthermore, microhardness measurements show an increase from HV 62 to HV 85 after the first pass of the CCEE and HV 73 after the second pass.

In the present study, the effects of rare earth element Y, texture intensity, and grain size on the tension-compression mechanical behavior of extruded Mg-XY(X = 0–3, wt pct) rods were investigated using improved phenomenological crystal plasticity. To this end, finite element modeling of a three-dimensional representative volume element (3D-RVE) was employed to consider the effects of microstructural parameters. Subsequently, the computational modeling approach was validated with the experimental data to assess the reliability of predictions of the responses of a polycrystalline aggregate. Afterward, the validated computational modeling was employed to predict the mechanical behaviors of extruded Mg-XY (X = 0–3, wt pct) by considering the role of slip/twinning activities during deformation. The results showed that the Y addition significantly improved the yield strength, ultimate strength, and ductility. Examination of the deformation modes activities indicated that the basal slip activity of extruded Mg-XY (X = 1–3, wt pct) is higher than that of extruded pure Mg due to the formation of non-basal texture components, which hindered the twinning activation. Increasing the Y content further reduced the suppression of tensile twinning activity. Therefore, the weak tension–compression yield asymmetry of extruded Mg-XY (X = 1–3, wt pct) was mainly attributed to the reduced tensile twinning activity. The simulated stress-strain curves illustrated that texture weakening, and grain refining improved the mechanical behavior and reduced tension-compression yield asymmetry.

Nuclear magnetic resonance (NMR) spectral analysis of biofluids can be a time‐consuming process, requiring the expertise of a trained operator. With NMR becoming increasingly popular in the field of metabolomics, there is a growing need to change this paradigm and to automate the process. Here we introduce MagMet, an online web server, that automates the processing and quantification of 1D 1H NMR spectra from biofluids—specifically, human serum/plasma metabolites, including those associated with inborn errors of metabolism (IEM). MagMet uses a highly efficient data processing procedure that performs automatic Fourier Transformation, phase correction, baseline optimization, chemical shift referencing, water signal removal, and peak picking/peak alignment. MagMet then uses the peak positions, linewidth information, and J‐couplings from its own specially prepared standard metabolite reference spectral NMR library of 85 serum/plasma compounds to identify and quantify compounds from experimentally acquired NMR spectra of serum/plasma. MagMet employs linewidth adjustment for more consistent quantification of metabolites from higher field instruments and incorporates a highly efficient data processing procedure for more rapid and accurate detection and quantification of metabolites. This optimized algorithm allows the MagMet webserver to quickly detect and quantify 58 serum/plasma metabolites in 2.6 min per spectrum (when processing a dataset of 50–100 spectra). MagMet's performance was also assessed using spectra collected from defined mixtures (simulating other biofluids), with >100 previously measured plasma spectra, and from spiked serum/plasma samples simulating known IEMs. In all cases, MagMet performed with precision and accuracy matching the performance of human spectral profiling experts. MagMet is available at http://magmet.ca. [ABSTRACT FROM AUTHOR]

In this research, we investigate the effects of various microstructural features on the behavior of spherical steel sheets, using the crystal plasticity finite element method. The cementite phase ratio, the grain sizes of ferrite and cementite, and the percentage of residual pearlite in the steel structure due to incomplete annealing are the major microstructural parameters studied in this work. A grain generator software has been developed to generate hexagonal ferrite grains as well as circular cementite particles distributed in the ferrite matrix. We use a hard coating with special properties as an intermediate layer around the cementite grains to simulate the contact between ferrite grains and cementite particles. This software can also assist with the preprocessing including boundary condition and load producing and introducing constitutive modeling relations. We use representative volume elements (RVEs) to simulate the microstructure of the steel sheet. The hardening parameters in the simulations are calibrated according to the available experimental data in the literature. Several RVEs were prepared and solved to investigate the effect of the thickness of this layer on material behavior. We can replicate the experimental results by setting the ratio of this thickness to the cementite particles' diameter to be 0.25. Moreover, by reducing the size of ferrite grains and cementite particles, the strength of steel increases. On the other hand, increasing the ratio of the cementite phase increases the strength of steel but the uniform plastic deformation of the material is reduced. We also model and discuss the remaining pearlite content and its effect on the flow behavior of the material. Finally, the effect of the cementite precipitation location and its bimodal size distribution were discussed in this study. [ABSTRACT FROM AUTHOR]