Switching of Control Mechanisms during the Rapid Solidification of a Melt Pool

The Solidification of Alloys is Typically Controlled by Solute Diffusion Due to the Solute Partitioning Happening at the Solid-Liquid Interface. in This Study, We Show that the Switching from Solute Diffusion-Controlled Growth to Thermal Diffusion-Controlled Growth May Happen at the Solidification Front during Rapid Solidification Processes of Alloys Such as Additive Manufacturing using a Phase-Field Model. the Switching is Found to Be Triggered by the Cooling of the Solid-Liquid Interface When It Becomes Colder Than the Solidus Temperature. the Switching Introduces a Sudden Jump of Growth Velocity, an Increase in Solute Concentration, and the Refining of the Resulting Microstructures. All Those Changes Predicted by the Phase-Field Simulations Agree with Experimental Observations Quantitatively. the Switching of Control Mechanisms Can Be Exploited by Manipulating the Processing Conditions to Form Refined Microstructures or Layered Structures for Improved Mechanical Properties

Separating sexual dimorphism from other morphological variation in a specimen complex of fossil marine reptiles (Reptilia, Ichthyosauriformes, Chaohusaurus).

The Early Triassic Chaohu Fauna from Anhui Province, China, contains the oldest record of Mesozoic marine reptiles, such as Cartorhynchus and Sclerocormus. Most specimens from the fauna belong to the ichthyosauriform Chaohusaurus, more specifically resembling C. chaoxianensis. However, a wide range of morphological variation exists within about 40 skeletons that have been prepared, likely reflecting mixed signals from both sexual and taxonomic differences. We test whether the sexual and taxonomic signals are separable based on quantification, aided by the knowledge of sexual dimorphism in extant marine tetrapods. There are two different suites of dimorphism that divide the specimens differently from each other yet consistently within each suite, resulting in four morphotypes in combination, likely representing two sexes of two taxa. Presumed males have larger organ of prehension sensu Darwin, specifically limbs in the present case, for a given body length. This sexing criterion is supported by the only specimen of a gravid female, which belongs to the morphotype with short limbs. Males also have larger skulls for the trunk length compared to females. This study demonstrates that sexual and taxonomic signals are separable in fossil reptiles, with a sufficient sample size and careful analyses

Why Are the Disabled People Willing to Participate in Sports: Taking Chinese Disabled Table Tennis Players as the Object of Investigation?

Abstract In this paper, questionnaire survey and data analysis are the main research methods. Its main purpose is to try to answer the question "why are the disabled people willing to participate in sports" and to explore some of the important factors that affect the participation of persons with disabilities. The object of the study is the 83 disabled table tennis players in the national training base. "Questionnaire of Motivation Adapted Athletes (AQAM)" is an international standard. Through descriptive analysis and independent sample T test data analysis, this study concludes three points: 1) "enhancing physical fitness", "loving table tennis sport" and "winning the respect of others" are the main reasons that contribute to the participation in sports of disabled persons; 2) The motives of male and female athletes with disabilities to participate in sports are quite different; 3) The sports participation motivation of persons with disabilities is positively related to their family circumstances

A porous metal-organic framework with ultrahigh acetylene uptake capacity under ambient conditions

Acetylene, an important petrochemical raw material, is very difficult to store safely under compression because of its highly explosive nature. Here we present a porous metal-organic framework named FJI-H8, with both suitable pore space and rich open metal sites, for efficient storage of acetylene under ambient conditions. Compared with existing reports, FJI-H8 shows a record-high gravimetric acetylene uptake of 224 cm(3) (STP) g(−1) and the second-highest volumetric uptake of 196 cm(3) (STP) cm(−3) at 295 K and 1 atm. Increasing the storage temperature to 308 K has only a small effect on its acetylene storage capacity (∼200 cm(3) (STP) g(−1)). Furthermore, FJI-H8 exhibits an excellent repeatability with only 3.8% loss of its acetylene storage capacity after five cycles of adsorption–desorption tests. Grand canonical Monte Carlo simulation reveals that not only open metal sites but also the suitable pore space and geometry play key roles in its remarkable acetylene uptake

Reliable Detection of Myocardial Ischemia Using Machine Learning Based on Temporal-Spatial Characteristics of Electrocardiogram and Vectorcardiogram

Background: Myocardial ischemia is a common early symptom of cardiovascular disease (CVD). Reliable detection of myocardial ischemia using computer-aided analysis of electrocardiograms (ECG) provides an important reference for early diagnosis of CVD. The vectorcardiogram (VCG) could improve the performance of ECG-based myocardial ischemia detection by affording temporal-spatial characteristics related to myocardial ischemia and capturing subtle changes in ST-T segment in continuous cardiac cycles. We aim to investigate if the combination of ECG and VCG could improve the performance of machine learning algorithms in automatic myocardial ischemia detection. Methods: The ST-T segments of 20-second, 12-lead ECGs, and VCGs were extracted from 377 patients with myocardial ischemia and 52 healthy controls. Then, sample entropy (SampEn, of 12 ECG leads and of three VCG leads), spatial heterogeneity index (SHI, of VCG) and temporal heterogeneity index (THI, of VCG) are calculated. Using a grid search, four SampEn and two features are selected as input signal features for ECG-only and VCG-only models based on support vector machine (SVM), respectively. Similarly, three features (S ( I ), THI, and SHI, where S ( I ) is the SampEn of lead I) are further selected for the ECG + VCG model. 5-fold cross validation was used to assess the performance of ECG-only, VCG-only, and ECG + VCG models. To fully evaluate the algorithmic generalization ability, the model with the best performance was selected and tested on a third independent dataset of 148 patients with myocardial ischemia and 52 healthy controls. Results: The ECG + VCG model with three features (S ( I ),THI, and SHI) yields better classifying results than ECG-only and VCG-only models with the average accuracy of 0.903, sensitivity of 0.903, specificity of 0.905, F1 score of 0.942, and AUC of 0.904, which shows better performance with fewer features compared with existing works. On the third independent dataset, the testing showed an AUC of 0.814. Conclusion: The SVM algorithm based on the ECG + VCG model could reliably detect myocardial ischemia, providing a potential tool to assist cardiologists in the early diagnosis of CVD in routine screening during primary care services