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Modeling of the Stress Path-Dependent Strain Ratcheting Behaviour of 304L Stainless Steel Through Crystal Plasticity Frameworks
No full textThis study investigates the strain ratcheting behavior of 304L stainless steel under complex stress-controlled cyclic loading conditions employing crystal plasticity models in the DAMASK framework. Strain ratcheting, a phenomenon characterized by the accumulation of plastic strain during cyclic loading, is particularly important in industries such as aerospace and nuclear energy, where components are subjected to non-proportional multiaxial loading. A polycrystalline representative volume element with 200 randomly oriented grains was generated to predict the material response under various stress paths, including Uniaxial, Shear, Cross, Square, and Circle loading conditions. Two crystal plasticity models were used: a phenomenological power-law (PP) model and a combined isotropic-kinematic hardening (IK) model. Simulations were conducted to identify parameters under monotonic and cyclic strain-controlled loading conditions. Model parameters are identified by using experimental results from literature and conducting strain-controlled uniaxial monotonic and cyclic loading simulations for PP and IK models, respectively. In addition, FEM and spectral solvers are compared for monotonic and cyclic loading conditions, and very similar macroscopic responses are obtained. The uniaxial strain ratcheting simulations under stress-controlled cyclic loading were compared against experimental data, with the IK model producing closer results due to its back-stress and memory terms. The analysis also revealed that the mechanical response, both at the macroscopic and local levels, is highly sensitive to the applied stress path, with significant differences in strain accumulation observed across different loading conditions. Torsional and axial strain evolutions were analyzed in detail, showing that the PP and IK models each performed better under certain stress paths. This study emphasizes the critical role of stress path effects in strain ratcheting and the variation in torsional and axial ratcheting predictions of two models for different stress paths
Tracking the Mode of Carbon Deposition During Dry Reforming of Methane over Ni/γ-Al2O3
No full textDry reforming of methane was studied over Ni/Al2O3 catalyst at 600 °C with varying CO2/CH4 ratios (0.2, 0.5, 1, 2, 5). 13CO2 as well as 12CO2 were used along with 12CH4 and resulting carbon was characterized with 13C solid state NMR spectroscopy in order to elucidate the role of CO2 in carbon build up. 13C NMR results revealed that carbon in the deposited coke not only came from CH4, but also from CO2. CO2 saturation coverage is determined by adsorption calorimetry as 0.02 mole/site at 323 K, populated on Al2O3. The critical CO2/CH4 ratio for the onset of carbon growth at atmospheric pressure was determined as 1.8 in good agreement with the literature. The effect of CO2/CH4 ratio on the type of carbon formation was investigated by HCTEM. Long-term reaction tests resulted in octopus carbon structure with several fibers growing from one nickel crystal. Above the critical CO2/CH4 ratio, carbon growth was inhibited, only a small amount of amorphous carbon could form. At CO2/CH4 ratios below the critical value, whisker formation was clearly observed. When the steady state operation of reforming reaction was changed to a transient operation by injecting pure CO2 flow to the reactor, coke deposition could be inhibited at the expense of hydrogen stoichiometry
THIENOTHIOPHENE Π-BRIDGE MODIFIED QUINOXALINE BASED CONJUGATED POLYMERS FOR ORGANIC SOLAR CELLS
No full textCongruence invariants of matrix mutation
No full textMotivated by the recent work of R. Casals on binary invariants for matrix mutation, we study the matrix congruence relation on quasi-Cartan matrices. In particular, we obtain a classification and determine normal forms modulo 4. As an application, we obtain new mutation invariants, which include the one obtained by R. Casals
Short-term electricity load forecasting with special days: an analysis on parametric and non-parametric methods
No full textAccurately forecasting electricity demand is a key business competency for firms in deregulated electricity markets. Market participants can reap significant financial benefits by improving their electricity load forecasts. Electricity load exhibits a complex time-series structure with nonlinear relationships among the variables. Hence, models with higher capabilities to capture such nonlinear relationships need to be developed and tested. In this paper, we present a parametric and a nonparametric method for short-term load forecasting, and compare the performances of these models for lead times ranging from 1 h to 1 week. In particular, we consider a modified version of the Holt-Winters double seasonal exponential smoothing (m-HWT) model and a nonlinear autoregressive with exogenous inputs (NARX) neural network model. Using hourly load data from the Dutch electricity grid, we carry out an extensive empirical study for five Dutch provinces. Our results indicate that NARX clearly outperforms m-HWT in 1-h-ahead forecasting. Additionally, our modification to HWT leads to a significant improvement in model accuracy especially for special days. Despite its simplicity, m-HWT outperforms NARX for 6- and 12-h-ahead forecasts in general; however, NARX performs better in 24-h-, 48-h- and 1-week-ahead forecasting. In addition, NARX provides drastically lower maximum errors compared to m-HWT, and also clearly outperforms m-HWT in forecasting for short holidays
Search for charged-lepton flavor violation in the production and decay of top quarks using trilepton final states in proton-proton collisions at (Formula presented)
No full textA search is performed for charged-lepton flavor violating processes in top quark ((Formula presented)) production and decay. The data were collected by the CMS experiment from proton-proton collisions at a center-of-mass energy of 13 TeV and correspond to an integrated luminosity of (Formula presented). The selected events are required to contain one opposite-sign electron-muon pair, a third charged lepton (electron or muon), and at least one jet of which no more than one is associated with a bottom quark. Boosted decision trees are used to distinguish signal from background, exploiting differences in the kinematics of the final states particles. The data are consistent with the standard model expectation. Upper limits at 95% confidence level are placed in the context of effective field theory on the Wilson coefficients, which range between (Formula presented) depending on the flavor of the associated light quark and the Lorentz structure of the interaction. These limits are converted to upper limits on branching fractions involving up (charm) quarks, (Formula presented) ((Formula presented)), of (Formula presented), (Formula presented), and (Formula presented) for tensorlike, vectorlike, and scalarlike interactions, respectively
N-cadherin mimetic hydrogels drive superior regenerative and paracrine responses in 3D cultures of adipose-derived mesenchymal stem cells
No full textBackground: Cadherin-based biomaterials play a pivotal role in influencing the fate of mesenchymal stem cells (MSC). Enhancing the adhesion of adipose tissue-derived MSCs has been shown to augment their paracrine effects while N-cadherin biomaterials have been suggested to regulate the paracrine effects of MSCs via specific growth factors although the precise mechanisms underlying this regulation remain insufficiently understood. This study aims to compare the effects of a 3D N-cadherin mimetic environment on cell viability, apoptosis, extracellular matrix regulation, and growth factor expression with those observed in traditional 2D and 3D spheroid cultures. Additionally, the study seeks to evaluate the effects of conditioned media derived from the N-cadherin mimetic environment on the viability and migration of endothelial cells. Materials and methods: Peptide hydrogels, including HAVDI and SCRAM, were used as N-cadherin mimetics at a concentration of 1 mM, and four experimental groups were established: 2D classical culture, 3D spheroid culture, 3D HAVDI, and 3D SCRAM. Cell viability was assessed using the MTT assay, while gene expression analysis (BCL-XL, BCL-2, BAX, MMP-9, TIMP1, MMP-2, PLAU, HGF, FGF, and VEGFR2) was performed via qRT-PCR. Secretion levels of growth factors (PDGF-BB, FGF-2, and VEGF-A) were quantified using ELISA. The effects of conditioned media on the proliferation and migration of human umbilical vein endothelial cells were evaluated through MTT assays, calcein staining, and wound healing assays. Results: In the 3D HAVDI group, where MSCs were cultured in an N-cadherin mimetic peptide environment, cell viability increased, and apoptosis decreased. Moreover, this environment upregulated genes associated with tissue remodeling and increased the expression and secretion of growth factors, compared to the classical 2D culture. Additionally, treatment with conditioned media at 1:2 and 1:5 dilutions significantly improved the viability and migration potential of endothelial cells. Conclusion: The N-cadherin mimetic peptide hydrogel represents a more effective culturing strategy than traditional 2D for enhancing the paracrine and regenerative properties of MSCs
Sources of variation in preschoolers’ relational reasoning: The interaction between language use and working memory
No full textPrevious research has suggested the importance of relational language and working memory in children's relational reasoning. The tendency to use language (e.g., using more relational than object-focused language, prioritizing focal objects over background in linguistic descriptions) could reflect children's biases toward the relational versus object-based solutions in a relational match-tosample (RMTS) task. In the lack of any apparent object match as a foil option, object-focused children might rely on other cognitive mechanisms (i.e., working memory) to choose a relational match in the RMTS task. The current study examined the interactive roles of language- and working memory-related sources of variation in Turkish-learning preschoolers' relational reasoning. We collected data from 4- and 5-year-olds (N = 41) via Zoom in the RMTS task, a scene description task, and a backward word span task. Generalized binomial mixed effects models revealed that children who used more relational language and background-focused scene descriptions performed worse in the relational reasoning task. Furthermore, children with less frequent relational language use and focal object descriptions of the scenes benefited more from working memory to succeed in the relational reasoning task. These results suggest additional working memory demands for object-focused children to choose relational matches in the RMTS task, highlighting the importance of examining the interactive effects of different cognitive mechanisms on relational reasoning. (c) 2024 Elsevier Inc. All rights are reserved, including those for text and data mining, AI training, and similar technologies
Genomic Variation in Vitis Vinifera, from Extant to Contemporary Varieties
No full textAncient DNA (aDNA) of 3500-year-old charred grapevine (Vitis vinifera) seed material excavated from the archaeological site of Kaymakçı, Gölmarmara, Türkiye, was subjected to whole genome shotgun sequencing using next-generation sequencing (NGS) technology. After grapevine DNA sequence data was filtered by quality scores and the grapevine DNA file was aligned with the two reference grapevine genomes (Pinot Noir-clone ENTAV115 and PN40024), 44 consensus mapped (CMap) ancient DNA sequences common to both reference genomes were obtained. Majority of these sequences (63.6%) were specific to the nuclear genome while 20.5% and 15.9% were specific to chloroplast and mitochondria genomes, respectively. Thus, 57.1%, 42.8%, and 100% of the CMap DNA sequences were related to previously identified genes in the grapevine nuclear, mitochondria, and chloroplast DNA genomes, respectively. Despite the vegetative propagation of grapevine, substantial base differences between ancient and modern varieties were found; that is, mean SNP (single nucleotide polymorphic) sites per the CMap DNA sequences varied between 1.71 in mitochondria and 2.89 in chloroplast sequences. In general, mean SNPs were low in the CMap DNA sequences annotated to known genes compared to those without any gene assignments. Further analysis of the association of the CMap DNA sequences of nuclear and organelle genomes with the SNP sites pointed out that base changes occurred in modern grapevine varieties compared to ancient grape variety involving genes controlling colour and aroma of grape fruits. To gain further insights about the role of domestication and clonal propagation in grape, future studies dealing with ancient grape DNA need to focus on certain gene regions using whole genome aDNA enrichment as the source of template DNA. The results of this study could provide invaluable reference information for identifying the genes or gene regions in such future studies. However, given the scarcity of ancient grape seeds, the degraded nature of ancient DNA, and measures to prevent contamination and bias, the limited CMap sequences likely represent only a small fraction of the ancient grapevine genome. Accordingly, the findings should be interpreted with these limitations in mind
Observation of Cosmic-Ray Anisotropy in the Southern Hemisphere with 12 yr of Data Collected by the IceCube Neutrino Observatory
No full textWe analyzed the 7.92 x 10(11) cosmic-ray-induced muon events collected by the IceCube Neutrino Observatory from 2011 May 13, when the fully constructed experiment started to take data, to 2023 May 12. This data set provides an up-to-date cosmic-ray arrival direction distribution in the Southern Hemisphere with unprecedented statistical accuracy covering more than a full period length of a solar cycle. Improvements in Monte Carlo event simulation and better handling of year-to-year differences in data processing significantly reduce systematic uncertainties below the level of statistical fluctuations compared to the previously published results. We confirm the observation of a change in the angular structure of the cosmic-ray anisotropy between 10 TeV and 1 PeV, more specifically in the 100-300 TeV energy range. For the first time, we analyzed the angular power spectrum at different energies. The observed variations of the power spectra with energy suggest relatively reduced large-scale features at high energy compared to those of medium and small scales. The large volume of data enhances the statistical significance at higher energies, up to the PeV scale, and smaller angular scales, down to approximately 6 degrees compared to previous findings