ABSTRACT
With the widespread application of computer technology in engineering education, Online Judge (OJ) systems have become an important platform for programming teaching. OJ systems provide a platform for learners to practice programming skills, submit solutions, and receive feedback. They offer a conducive environment for learners to engage in hands-on coding exercises and enhance their programming abilities. This article explores the use of OJ systems as a software tool for enhancing programming education in engineering. It investigates how the difficulty and order of programming problems affect the users' behavior, performance, and cognitive load in OJ environments. The research data were sourced from Project_CodeNet. Using statistical methods, such as Spearman correlation analysis and differential analysis, the study reveals the factors that influence the users' submission situations, answer order, and learning outcomes. The findings provide useful implications for OJ system developers, teachers, and learners in designing, implementing, and using OJ systems for programming education in engineering. The study suggests that problem difficulty and order should be considered and adjusted according to the users' abilities and progress, to provide appropriate challenges and support, balance the cognitive load, and improve the programming skills of the users.
ABSTRACT
Highly sensitive and selectivite detection of copper ions (Cu2+) and hydrogen sulfide (H2S) have become important research topics due to the potential harmful impacts of these chemicals to human health and the environment. In this study, we report the synthesis of a dual-functional peptide-based probe L (FITC-AhxSerSerHis), designed to mimic a copper-sulfur metalloprotein, and capable of continuous detection of Cu2+ and S2- based on colorimetric and fluorescent methods. The new probe L displayed excellent "turn off" fluorescence response and good selectivity for Cu2+ ions via a modification of the tripeptide and fluorescein isothiocyanate group, and produced an obvious color change visible to the naked eye. Furthermore, as an excitable probe, the L-Cu complex could continuously detect S2- with high selectivity and sensitivity in 100% aqueous buffered solutions. The detection limits for fluorescence titration measurements, calculated using the equation 3σ/k, were 76.7 nM (Cu2+) and 27.2 nM (S2-), which were well below U.S. EPA safety levels. In addition, L could be cycled to alternately detect Cu2+ and S2-, thereby making it a promising reversible probe. Moreover, L was successfully applied to monitoring Cu2+ and S2- in live RKO cells through fluorescence imaging, exhibiting low cytotoxicity and good cell permeability.
