Correction Factor Research Articles

Charge radii of 11−16C, 13−17N and 15−18O determined from their charge-changing cross-sections and the mirror-difference charge radii

Charge-changing cross-sections (CCCSs) of 11−16C, 13−17N and 15−18O on a carbon target have been determined at energies around 300 MeV/nucleon. A nucleon separation energy-dependent correction factor has been introduced to the Glauber model calculation for extracting the nuclear charge radii from the experimental CCCSs. The charge radii of 11C, 13,16N and 15O thus were determined for the first time. With the new radii, we studied the experimental mirror-difference charge radii (ΔRchmirror) of 11B-11C, 13C-13N, 15N-15O, 17N-17Ne pairs for the first time. We find that the ΔRchmirror values of 13C-13N and 15N-15O pairs follow well the empirical relation to the isospin asymmetry predicted by the abinitio calculations, while ΔRchmirror of 11B-11C and 17N-17Ne pairs deviate from such relation by more than two standard deviations.

PHSOR10 Presentation Time: 9:45 AM: Experimental Verification of 106Ru Brachytherapy Dosimetry Data Using Diodes with Traceability to EBRT Metrology Standard and Monte Carlo Calculated Beam Quality Correction Factors

PHSOR10 Presentation Time: 9:45 AM: Experimental Verification of 106Ru Brachytherapy Dosimetry Data Using Diodes with Traceability to EBRT Metrology Standard and Monte Carlo Calculated Beam Quality Correction Factors

Optimization of border irrigation variables based on a correction factor for irrigation quota

The optimization of surface irrigation variables, i.e., the selection of the optimal combination of the inflow rate per unit width (q) and cutoff time (tco), is essential for obtaining high performance. The main objective of this study was to optimize irrigation variables by considering different irrigation requirements and the total loss model, which includes the irrigation water loss and crop yield loss. A correction factor for the irrigation quota (Cf) was introduced to achieve this objective. Cf considers different irrigation requirements, as it represents the ratio of the actual irrigation quota for certain irrigation to the designed irrigation quota (Dreq). Uniform design theory was used to determine random combinations of q and Cf from a selected range. The q value ranged from 3 to 9 L.m-1. s-1. Because the actual irrigation quota does not greatly deviate from the design irrigation quota, Cf should reach approximately 1.00. The selected Cf ranged from 0.80 to 1.38. To obtain higher crop yields, lower economic losses, and more reasonable design variables for surface irrigation, a total loss model for uneven border irrigation was established, which was defined as the objective function to optimize border irrigation design—the total loss model was combined with uniform design theory and the WinSRFR model to analyze different scenarios. The results showed that Cf has a clear meaning and exerts a favorable application effect on the irrigation performance evaluation indicators and can be used to design border irrigation systems. Based on the total loss model for uneven border irrigation, the optimal irrigation variables q and Cf for design irrigation quotas of 60, 80, and 100 mm are q=6.22 L.m-1. s-1 and Cf=1.17; q=4.60 L.m-1. s-1 and Cf=1.14; and q=3.80 L.m-1. s-1 and Cf=1.10, respectively. Compared with the conventional design results, q in the optimal design results based on the loss model decreased, Cf increased, and the total loss significantly decreased. Optimization of irrigation variables based on the border irrigation loss model could ensure favorable irrigation performance evaluation indicators, improve the water use efficiency, provide higher crop yields, and minimize the total economic losses caused by uneven irrigation.

Accelerating pharmaceutical tablet development by transfer of powder compaction equipment across types and scales

Roller compaction is a key unit operation in a dry granulation line for pharmaceutical tablet manufacturing. During product development, one would like to find the roller compactor (RC) settings that are required to achieve a desired ribbon solid fraction. These settings can be determined from the compression profile of the powder mixture being compacted and a mathematical model that interprets it. However, establishing compression profiles in an RC requires relatively large amounts of powder, which are expensive and may not be available during drug development. As a cost-effective alternative to an RC, a compactor simulator (CS) can be used, which is a small-scale equipment that uses minimal amounts of powder to build the compression profile. However, since the working principles of a CS and an RC are different, the compression profiles obtained from the two devices for a given powder are also different. In this study, we propose a transfer learning approach that allows the RC compression profile of a given powder to be easily predicted from the compression profile obtained in a CS for the same powder. Based on the well-known Johanson model and on the mass correction factor theory, we examine the compaction behavior of six formulations, two of which including active ingredients, and we find that the mass correction factor does not depend significantly on the powder being compacted. We develop a simple, generalized correlation (transfer model) that allows the mass correction factor to be predicted solely as a function of the pressure at which the compaction is carried out. By using the proposed transfer model, the prediction of the RC compression profiles for the validation powders is significantly improved over the case where a constant value of the mass correction factor is used.

Effective stress intensity factor range for fatigue cracks propagating in mixed mode I-II loading

The actual service axles are often subjected to mixed-mode loading, and predicting the mixed-mode I-II crack propagation behaviour using the mode I effective stress intensity factor (ΔKI) differs from the real service conditions. To effectively predict the fatigue crack propagation behaviour of actual service structures, the I-II stress intensity factor range (ΔKP-R) considering two closure effects was adopted to describe the fatigue crack propagation under mixed mode loading. A test database was established based on monitoring data of mode I and mixed-mode I-II (30/45/60°) crack propagation tests under different stress ratios. Combining domain knowledge and symbolic regression (SR) methods, an angle factor was proposed for constructing correlation functions between ΔKI and ΔKP-R. The results showed that the loading angle (α) only affects the initial projection of the load parallel and perpendicular to the fatigue crack growth (FCG) direction. Compared with the geometric correction factor, the correlation function acquired by the angle factor constructed by the SR method has higher accuracy, and the balance parameters (SCORE) obtained by the former are significantly higher than those obtained by the latter under the same function complexity. The SR verification results demonstrated that constructing mode I and I-II correlation functions with angle factors has a good predictive effect.

Laboratory support for seromonitoring of anti-pertussis post-vaccination immunity

Monitoring of humoral immunity in 3–4 year-old anti-pertussis vaccinated children is one of the approaches for pertussis epidemiological surveillance. It’s a predictive indicator for comprehensive assessment of morbidity in the region. The agglutination reaction (RA) used earlier has been displaced with enzyme immunoassay (ELISA). So, two questions arose: regarding i) a relevance of using ELISA in whole-cell vaccinated individuals, and ii) correctness of large-scale data interpretation without applying a unified IgG reference value. Study aims were to assess humoral anti-pertussis population immunity by ELISA, to determine features of humoral protection in vaccinated subjects after using various vaccine types, to identify age features, to make recommendations for evaluating seromonitoring data. Blood serum samples from anti-pertussis vaccinated children in Samara region (n = 1729) were examined in 2016–2020; children were divided into 4 age groups ( 3, 3–4, 5–7, ≥ 7.1 years) and into 3 type vaccines groups: cellular, acellular and combined. We used two ELISA kits, which are designed to assess post-vaccination immunity, according to the manufacturer’s instructions, quantifying IgG againstB. pertussis, which differ in units and reference values. Statistical analysis was performed using StatTech program v.2.6.2. The largest and smallest percentage of seronegative children was in the cellular-vaccinated and acellular-vaccinated group, respectively. Seronegative percentage in the “indicator group” reaches 55.2% being significantly higher than acceptable 10.0%-level, and differs from the literature data (30–40%), which were obtained mainly with RA. This may suggest about an incorrect interpretation of post-vaccination immunity data evaluation strictly according to manufacturers’ reference criteria, especially for whole-cell vaccinated subjects. A method for calculating the seronegative percentage is proposed that relies on the prognostic negative data level as a correction factor. The required values were obtained during comparison studies of random serum samples from 3–4-year-old children (n = 70) using two ELISA kits (“RIDASCREEN®Bordetella”, “SeroPertussis™ IgG”) and intra-laboratory comparison panel. It should be given preference for sets with a greater prognostic negative data level, if population seronegative percentage is assessed.

A Proposal for a High-Frequency Earthquake Magnitude (m3Hz) for Seismic Hazard and Rapid Damage Assessment

Abstract Obtaining a size estimate of an earthquake that well represents its potential impact is of primary importance in seismology and earthquake engineering. The magnitude scales currently used in earthquake catalogs, mainly Ms and Mw, are not designed to represent the variability of shaking due to variations in high-frequency radiation. Conversely, ML, which best describes the seismic-wave energy released by an earthquake, is unable to provide an accurate representation of events with magnitudes exceeding approximately 6.5. Therefore, building on and extending the concept of high-frequency magnitude (Atkinson and Hanks, 1995), we propose in this article a new high-frequency magnitude scale m3Hz. This magnitude is estimated by also considering correction factors for the crustal model and site effects. We apply the new magnitude scale m3Hz to two data sets (Central Italy and Japan) and validate its ability to capture high-frequency radiation effects through comparison with available source parameters. Finally, a procedure for estimating m3Hz is also proposed for preinstrumental earthquakes. This procedure addresses a limitation of previous magnitude estimation techniques, such as Me, and is validated for four events for which both macroseismic and instrumental intensity data are available.

A numerical study of Lamb wave localization in thin plates using a passive co-linear phased array

Lamb waves have become increasingly popular in the field of aerospace vehicle non-destructive testing and evaluation as well as structural health monitoring. These guided waves possess the ability to travel long distances and exhibit a notable inclination to interact with existing damage. This work has numerically explored for the first time the use of a passive co-linear phased array to localize emission sources over a wide range of variables. Three localization methods are explored, namely, reverse beamforming, wavefront curvature ranging, and hyperbolic lateration in a direction comparison without modeling transducers. It was shown that both reverse beamforming and wavefront curvature ranging could localize an emission with <1% error in both range and bearing, while hyperbolic lateration was significantly worse. A relationship between bearing error and bearing was demonstrated, presenting the ability to develop new methods with correction factors that can localize emissions with even greater accuracy.

Investigating the impact of nano copper on the electrical conductivity of aluminum: a comprehensive study utilizing genetic algorithms methods

Nanotechnology has emerged as a transformative field in material science, offering unprecedented opportunities to enhance the electrical properties of conventional materials through the incorporation of nano-sized particles. In this extensive study, we explore the effects of varying weight percentages (1%, 2%, and 3%) and lengths (30 nm, 60 nm, 150 nm, and 250 nm) of nano copper on the electrical conductivity of aluminum (Al) across different temperatures (20°C, 50°C, 80°C, and 100°C). Additionally, GA method and Numerical correction factor and constitutive equation using Zener –Holloman parameter were employed for modeling the rheological behavior of Al based on these parameters.

The Interplay between the Disk and Corona of the Changing-look Active Galactic Nucleus 1ES 1927+654

Time-domain studies of active galactic nuclei (AGNs) offer a powerful tool for understanding black hole accretion physics. Prior to the optical outburst on 2017 December 23, 1ES 1927+654 was classified as a “true” type 2 AGN, an unobscured source intrinsically devoid of broad-line emission in polarized spectra. Through our 3 yr monitoring campaign spanning X-ray to ultraviolet/optical wavelengths, we analyze the post-outburst evolution of the spectral energy distribution (SED) of 1ES 1927+654. Examination of the intrinsic SED and subsequent modeling using different models reveal that the post-outburst spectrum is best described by a combination of a disk, blackbody, and corona components. We detect systematic SED variability and identify four distinct stages in the evolution of these components. During the event the accretion rate is typically above the Eddington limit. The correlation between ultraviolet luminosity and optical to X-ray slope (α OX) resembles that seen in previous studies of type 1 AGNs, yet exhibits two distinct branches with opposite slopes. The optical bolometric correction factor (κ 5100) is ∼10 times higher than typical AGNs, again displaying two distinct branches. Correlations among the corona optical depth, disk surface density, and α OX provide compelling evidence of a disk–corona connection. The X-ray corona showcases systematic variation in the compactness-temperature plot. Between 200 and 650 days, the corona is “hotter when brighter,” whereas after 650 days, it becomes “cooler when brighter.” This bimodal behavior, in conjunction with the bifurcated branches of α OX and κ 5100, offers strong evidence of a transition from a slim disk to a thin disk ∼650 days after the outburst.

The role of volume averaging effects, beam hardening, and phantom scatter in dosimetry of grid therapy

Abstract Objective: Current reference dosimetry methods for spatially fractionated radiation therapy (SFRT) assume a negligible beam quality change, perturbation, or volume-averaging correction factor. Therefore, the aim of this work was to investigate the impact of the grid collimators on the dosimetric characteristics of a 6 MV photon beam. A detector-specific correction factor, k_(Q_grid,Q_msr)^(f_grid,f_msr ), was proposed. Several dosimeters were evaluated for their ability to measure both reference dose and grid output factors (GOFs).&amp;#xD;Approach: A Monte Carlo model of a grid collimator was created to study the change in the depth dose characteristics with the grid collimator. The impact of the collimator on the percent depth dose (PDD), electron contamination, and average photon energy was investigated. The k_(Q_grid,Q_msr)^(f_grid,f_msr) correction factors were calculated for two reference-class micro ion chambers. The reference dose and GOFs were measured with a grid collimator using six ion chambers, two silicon diodes, and a diamond detector.&amp;#xD;Main results: The PDD in the presence of the grid was observed to be steeper compared to the open field. The average photon energy increased from 1.33 MeV to 1.74 MeV with the presence of the grid collimator. The dose contribution by scattered photons was significantly higher at deeper regions for the open field compared to the grid field. The k_(Q_grid,Q_msr)^(f_grid,f_msr) correction was calculated to be &lt;0.5%. The reference dose for all detectors, except for the CC13 and CC04 chambers, was within 1% of each other. The CC13 under-responded up to 3.2% due to volume-averaging effects. The GOFs calculated for all detectors, except Razor and A16, were within 1% of each other.&amp;#xD;Significance: The phantom scatter dictates the change in the PDD with the presence of the grid. The micro ion-chambers exhibit negligible k_(Q_grid,Q_msr)^(f_grid,f_msr) correction. All detectors, except the CC13 ion chamber, were found to be suitable for SFRT reference dosimetry.

Complete vs culprit-lesion-only myocardial revascularization in patients with out-of-hospital cardiac arrest: insights from the multicentric "Lombardia CARe" registry

Abstract Background Out-of-hospital Cardiac Arrest (OHCA) is a potentially devastating complication of patients with Myocardial Infarction (MI). Multivessel Disease (MVD) is a frequent occurrence in this setting, being present in nearly half patients undergoing Coronary Angiography (CAG). We previously reported that, in case of MI complicated by OHCA and evidence of MVD, a complete myocardial revascularization, as compared to culprit-lesion-only revascularization, was associated with an improved 1-year survival and favorable neurological outcomes. We aimed to validate and confirm these results on a multicentric scale with a larger patient cohort. Methods This is a multicentric, prospective, observational study. We considered all the consecutive patients with OHCA and MI enrolled in the Lombardia CARe Registry from January 1st 2015 to December 31st 2022 who underwent CAG in 6 centers in Northen Italy. Results A total of 623 patients were included; of these, 403 underwent CAG. Median age was 64 years, and about 80% had no previous history of ischemic heart disease. Median ejection fraction (EF) at presentation was 40%. MVD was present in 186 (46.1%) patients and was subsequently treated with either complete (32.3%) or incomplete (67.7%) coronary revascularization. Left anterior descendent (LAD) artery was the culprit lesion in almost 1/3 of patients. The 1-year survival rate was 78.3% in the complete revascularization group and 42.9% in the culprit-lesion-only revascularization group (p-value &amp;lt; 0.001). After correction for factors that were predictors on univariate analysis, complete revascularization strategy was independently associated with a reduced risk of death [HR: 0.27 (95% CI: 0.01 to 0.739; p = 0.01] and death or unfavorable neurological outcome [HR: 0.23 (95% CI: 0.08 to 0.67); p = 0.007]. Conclusions Complete revascularization strategy was confirmed to be associated with an improvement of 1-year survival and with a good neurological outcome in patients resuscitated from OHCA. These results highlight the independent impact on survival of a complete coronary intervention strategy in patients with OHCA plus MVD.

On the Use of Image Analysis for Hematocrit Evaluation in Dried Blood Spots

Dried blood spots (DBSs) are formed by collecting a small sample of blood on specialized filter paper and allowing it to dry naturally. Various domains of life sciences and drug research extensively use DBSs as a sampling technique. The “Hematocrit (Ht) effect” affects assay bias, and several strategies have been put forth to deal with it, including the correction of quantified concentrations using an appropriate correction factor. The approach was previously applied, following the utilization of an image processing algorithm developed in Matlab® to derive a reliable equation correlating DBS areas to Ht% values. The present work looks more closely at the application of image analysis to the evaluation of Ht in DBS samples. Utilizing image analysis software, DBS samples with known Ht values were processed. Preparation of cards has followed a previously developed protocol for the appropriate formation of uniform area DBSs, irrespective of Ht. The resulting areas showed close resemblance to the respective theoretical areas calculated by applying the correlation equation. Following that, the equation was utilized to determine the Ht values for each sample, and a comprehensive comparison of measured versus calculated Ht was carried out using various statistical approaches for method comparison. The results demonstrated a strong correlation, suggesting the method’s viability in estimating Ht for unknown DBS samples.

AI-based algorithm for assessing coronary artery calcium score on contrast-enhanced cardiac computed tomography scans

Abstract Introduction In cardiac computed tomography (CT) examinations, non-contrast scans are often performed in addition to contrast-enhanced scans to quantify the coronary artery calcification (CAC) score. These calcium score scans are associated with additional exposure to ionizing radiation. Purpose We sought to develop a fully automated artificial intelligence (AI)-based algorithm capable of determining CAC score based solely on contrast-enhanced CT scans, eliminating the need for additional non-contrast scans. Methods An automated CAC scoring algorithm on contrast-enhanced CT scans was developed and trained using a dataset of 297 cardiac CT studies. Coronary artery calcifications were manually segmented in contrast-enhanced scans using a threshold of 2 standard deviations above the mean attenuation value of the ascending aorta. On non-contrast scans, CAC was manually assessed using a standard threshold of ≥130 Hounsfield Units. A correction factor for calcium score results assessed on contrast-enhanced scans was determined using linear regression. The algorithm was tested on an independent set of 90 contrast-enhanced CT scans (four manufacturers, eight scanner models). We compared automated CAC scores to manual expert reader reference assessments on non-contrast CT scans. CAC scores were categorized into four risk categories following the Society of Cardiovascular Computed Tomography recommendations: 0, 1-100, 101-300, and &amp;gt;300 Agatston Units. Results In the assessment of 90 CT studies (mean age 61.0±11.4 years, 46.7% males), the AI-model detected CAC in 69 contrast-enhanced scans (76.7%), comparable to the human reader's detection rate of CAC in 71 non-contrast scans (78.9%) (p = 0.63). The CAC score was initially calculated using AI-based segmentation of coronary calcification on contrast-enhanced scans and then the result was multiplied by established linear correction factor of 1.97. There was an excellent correlation between AI-model and manual reference total CAC scores (Pearson’s r = 0.96, 95% CI 0.94–0.97, p &amp;lt; 0.001). The model correctly classified 77 patients (85.6%) into the same CAC risk category as the human reader (Figure 1). Among 19 patients (21.1%) with a CAC score of zero, only 1 patient (5.3%) was reclassified with a non-zero CAC score by the AI-model. Cohen’s kappa value for CAC score risk categorization was 0.80 (p &amp;lt; 0.001), indicating very good agreement (Figure 2). Bland–Altman analysis revealed minimal bias of -9.7 Agatston Unit with 95% limits of agreement ranging from -184.8 to 165.5 Agatston Unit. Conclusions CAC score can be accurately quantified on contrast-enhanced cardiac CT scans using an automated AI-based algorithm. This approach has the potential to eliminate the necessity for an additional non-contrast CT scan, thereby reducing the patient's exposure to ionizing radiation.

Correlation between LDL/HDL-cholesterol ratio and long term prognosis after acute coronary syndrome and severity of coronary artery disease

Abstract Introduction Dyslipidaemia is an important correctable risk factor for coronary artery disease (CAD). Many studies have confirmed that the lower the low-density lipoprotein cholesterol (LDL-C) levels are, the lower is the CAD morbidity and mortality rates (1). However, many patients who achieved low levels of LDL-C still experience a major adverse cardiovascular event (MACE) because of the other residual risk factors. Therefore, there is a constant need for better stratification of patients who are at higher risk for novel MACE following their first acute coronary syndrome (ACS). Evidence increasingly suggests that the ratio of LDL-C/HDL-C might be a new and better marker of cardiovascular disease, as it simultaneously evaluates the levels of both LDL-C and HDL-C (2). Purpose The aim of this study was to investigate the prediction value of LDL-C/HDL-C ratio for long term prognosis after ACS as well as its correlation with CAD severity. Methods We included patients hospitalized at out centre with ACS from January 2017 to January 2024. Demographic data, data on LDL-C and HDL-C levels on admission and calculated Syntax score were used. Syntax score is a comprehensive angiographic scoring system which determines complexity by using coronary anatomy and lesion characteristics (3). Follow-up data were collected either by clinical follow-up visits or by telephone interviews. The MACE was defined as the composite of cardiovascular death, acute coronary syndrome and need for elective or urgent percutaneous or surgical revascularization. Results This registry-based study included 2471 patients with ACS, median age of 64 (interquartile range 56-73) years, 31% female. Total of 1099 patients (44%) had non-ST elevation ACS and 1372 (54%) had ST elevation myocardial infarction (STEMI). Median Syntax score was 13 (IQR 7-20.5), with 1494 (61%) patients having low Syntax score (≤16), 508 (21%) patients medium (16-22), and 448 (18%) high score (&amp;gt;22), respectively. Median follow up was 17 (3-27) months. LDL-C/HDL-C ratio correlated significantly with cardiovascular death, with weak coefficient (2.94 vs. 2.54 p&amp;lt;0.001; rho=0.102, p&amp;lt;.0001), however did not correlate with MACE (2.88 vs. 2.92, p=0.188, rho=0.06, p=0.77). This remained identical when tested for patients with STEMI and non-STE ACS. In addition, LDL-C/HDL-C ratio did not correlate with CAD severity as assessed with Syntax score (low 2.92 vs. medium 2.83 vs. high 2.86, p=0.597; rho=0.4, p=0.09). Conclusion Our data suggest that LDL-C/HDL-C ratio cannot be used as a relevant predictor of post-ACS long-term MACE or cardiovascular death, nor it can be correlated with CAD severity. Further studies are needed to establish the real value of LDL-C/HDL-C ratio as a post-ACS predictor.

Vibration analysis using the theory of exponential shear deformation for laminated plates

In this research, the free vibration response of laminated composite plates is studied using a refined exponential shear strain theory. The most interesting feature of this theory is that it allows exponential distributions of transverse shear strains, and verifies zero-shear boundary conditions on the plate surfaces without the use of shear correction factors. Some stiffness constants are written as a series. The number of independent unknowns in the present theory is four, compared with five in other shear deformation theories. The equations of motion are obtained from Hamilton's principle and Navier's method is used to determine the exact solution for antisymmetric cross-laminated plates. The numerical results found in the present analysis for free vibration are presented and compared with those available in the literature. The proposed theory is not only accurate, but also effective in predicting the fundamental frequencies of laminated composite plates.

Capillary drops, capillary pooled, and venous blood samples for determining hemoglobin concentration using HemoCue: A measurement system analysis.

Several external and internal factors can affect the performance and variability of Hemoglobin concentration [Hb] measurements using HemoCue, and documentation on the contribution of different sources of [Hb] variation is limited. We used an experimental repeated measurements design with nine randomly selected participants, three HemoCue devices, and three trained field workers. HemoCue measurements for all samples were repeated three times. The [Hb] measurement system considers four sources of error: 1) HemoCue devices, 2) field workers, 3) between individuals, and 4) within individuals. A concordance analysis was used to assess accuracy and precision, and a linear mixed model was used to estimate mean differences (bias) from blood specimens, anticoagulants, and to estimate the contribution of the 4 sources of error to [Hb] measurements. Positive mean [Hb] differences were found: 1.34 g/dL for capillary drops, 0.81 g/dL for pooled capillary blood samples, 0.756 g/dL for venous blood stored with EDTA, and 0.911 g/dL for venous blood stored with heparin. The mean [Hb] difference for venous blood with EDTA was used as a correction factor for all results measured using a HemoCue. After adjustment, capillary drops showed a mean difference of 0.585 g/dL, and pooled capillary samples were not significantly different. The individual variability was 95.8% of total variance, HemoCue devices contributed 2.1% of measurement error, field staff contributed 0.4%, and the residual was 1.7%. The HemoCue [Hb] measurement system is reliable in controlled environments, with a small measurement error of 4.2%.

Characterization of Interface Transition Zone in Asphalt Mixture Using Mechanical and Microscopic Methods

An enormous surge in the pavement sector requires the evaluation of interface bonding in asphalt composite, since the assessment of bonding brings considerable cost savings. Microscopic and mechanical analyses were performed to study the status of the interface transition zone of four groups of asphalt mixtures, using thin-slice preparation to obtain asphalt mixture slices with a flat surface for microscopic analysis. The interface transition zones were characterized using good knowledge of blending or diffusion phenomena by conducting tests both at the micro and macro levels to determine mixture quality. Asphalt mixture components were observed using fluorescence microscopy imaging and evaluated by the gray value change law. Asphalt mixture groups, (virgin, recycled of 30% aged and 70% unaged, 6%, and 4% rejuvenator dosage mixtures) under the same process parameters, which are a mixing time of 270 s and a mixing temperature of 150 °C, been considered optimum for component fusion in a hot asphalt mixture were used. This study relied on the influence of morphology law, assessed through rutting tests for high temperature performance, semi-circular bending tests for low temperature performance, and pull-off tests for interface bonding strength. The relationship between interface transition zones and macro performance was studied. The self-developed pull-off method was a research innovation which can be used as an alternative to study interface transition zones in asphalt mixtures, and provides the necessary data needed with 3D surface failure mode calculations. The device measured the bonding strength of a single aggregate in distinct positions using the bitumen penetration test method. The main goals were to determine a correction factor, identify the appropriate alteration, and compute the actual fracture surface area. Using scanning electron microscopy for interface characterization and micro-morphologies of mortar transition zone, our analysis provides adequate knowledge about interface position and the components present. The applied approaches to characterize asphalt mixture interfaces proved workable and reliable, as all methods have similar trends with useful information to determine asphalt pavement quality.

Ultralow thermal conductivity in Si–Ge nanograin mixtures: A cost-effective granular material for thermoelectric applications

This paper presents a theoretical study of the thermal conductivity of Si–Ge nanograin mixtures using a multiscale computational methodology based on solving the Boltzmann transport equation for phonons with first-principles techniques. A size-dependent correction factor is developed to account for the spatial dependence of the phonon distribution function on nanograin size, with parameters derived from the phonon properties of infinite Si and Ge crystals. This approach makes it possible to accurately calculate the thermal conductivity within a single nanograin, using force constants obtained from first-principles calculations. Thermal energy transport by phonons across grain boundaries is modeled by accounting for phonon transmission by two-phonon processes, weighting specular, and diffuse transmission for each phonon mode as a function of the root-mean-square roughness of the boundary relative to the phonon wavelength. The boundary thermal conductance model, previously validated against experimental data, is implemented using first-principles techniques. This approach excludes specular transmission for phonon modes with specific symmetries while ensuring conservation of the total number of modes in each symmetry class. The study examines the influence of grain size, nanograin mixture composition, temperature, and boundary asperities on the thermal conductivity of nanograin mixtures.

Prediction of Temperature‐Dependent Stress in 4H‐SiC Using In Situ Nondestructive Raman Spectroscopy Characterization

Abstract4H‐SiC is widely used in power electronics owing to its superior physical properties. However, temperature‐induced stresses compromise the reliability of 4H‐SiC power devices in high‐temperature applications, warranting precise, and nondestructive stress characterization responsive to temperature variations. Herein, a temperature‐dependent predictive model is proposed for analyzing the Raman shift–stress in 4H‐SiC. The 4H‐SiC epitaxial samples prepared via chemical vapor deposition are characterized using in situ variable‐temperature Raman spectroscopy, resulting in a temperature correction factor of approximately −0.021 cm−1 K−1, which is integrated into the conventional Raman shift–stress relationship to assess stress variations induced by temperature variations. The elastic modulus tensor of 4H‐SiC at various temperatures determined using molecular dynamics simulations indicates a linear reduction in modulus with increasing temperature. This variable temperature modulus is incorporated into the Raman shift–stress relationship. Furthermore, a finite element method is used for model simplification to perform stress calculations in three axial directions. The experimental results confirm the consistency between calculated and experimental values with a 10% error range under the uniaxial stress condition. The study findings provide valuable insights into assessing stress evolution in 4H‐SiC under temperature variations based on Raman spectroscopy, thereby advancing the application of spectroscopic techniques in material stress detection.