Gas Chromatography-High Resolution Tandem Mass Spectrometry Using a GC-APPI-LIT Orbitrap for Complex Volatile Compounds Analysis

A new approach of volatile compounds analysis is proposed using a linear ion trap Orbitrap mass spectrometer coupled with gas chromatography through an atmospheric pressure photoionization interface. In the proposed GC-HRMS/MS approach, direct chemical composition analysis is made for the precursor ions in high resolution MS spectra and the structural identifications were made through the database search of high quality MS/MS spectra. Successful analysis of a complex perfume sample was demonstrated and compared with GC-EI-Q and GC-EI-TOF. The current approach is complementary to conventional GC-EI-MS analysis and can identify low abundance co-eluting compounds. Toluene co-sprayed as a dopant through API probe significantly enhanced ionization of certain compounds and reduced oxidation during the ionization

Microstructure Design of Multifunctional Particulate Composite Materials using Conditional Diffusion Models

This paper presents a novel modeling framework to generate an optimal microstructure having ultimate multifunctionality using a diffusion-based generative model. In computational material science, generating microstructure is a crucial step in understanding the relationship between the microstructure and properties. However, using finite element (FE)-based direct numerical simulation (DNS) of microstructure for multiscale analysis is extremely resource-intensive, particularly in iterative calculations. To address this time-consuming issue, this study employs a diffusion-based generative model as a replacement for computational analysis in design optimization. The model learns the geometry of microstructure and corresponding stress contours, allowing for the prediction of microstructural behavior based solely on geometry, without the need for additional analysis. The focus on this work is on mechanoluminescence (ML) particulate composites made with europium ions and dysprosium ions. Multi-objective optimization is conducted based on the generative diffusion model to improve light sensitivity and fracture toughness. The results show multiple candidates of microstructure that meet the design requirements. Furthermore, the designed microstructure is not present in the training data but generates new morphology following the characteristics of particulate composites. The proposed approach provides a new way to characterize a performance-based microstructure of composite materials

Physical activity and depression: Nationwide evaluation of depression and physical activity in South Korea

Purpose: The relationship between depression and physical activity levels in adults in Korea was determined using data from the National Health and Nutrition Survey (K-NAESE). METHODS: Data collected from K-NAESE between 2014 and 2020, comprising 29,716 (male: 13,416, female: 16,300) participants, were analyzed using a complex sample statistical analysis by applying differential weight to the variables to analyze the relationship between depression and physical activity levels in an estimated South Korean population (50,881,242). Demographic factors were used as control variables while constructing an independent variable-by-variable fit model for the zero-inflated Poison Regression analysis of PHQ-9 depression scores, and a meaningfully interpretable fit model was used in the final model. RESULTS: A significant relationship was observed between the total PHQ-9 score and commute physical activity (OR=1.042; SE, 0.006; p\u3c.001) and moderate-intensity leisure and physical activity time (OR=1.116; SE, 0.008; p\u3c.001). A significant association was found between the PHQ-9 scores and physical factors (grip strength; OR=0.985; SE, 0.001; p\u3c.001). Using Binomial Logistic Model for Depression Classification, a significant association was observed for classification as low/high-risk depression in individuals without moderate-intensity physical activity (OR=1.190; SE, 0.046; p\u3c.001). Furthermore, individuals with a high grip strength were classified as low/high-risk depression compared to a normal grip strength (OR=0.980; SE, 0.004; p\u3c.001). CONCLUSIONS: These findings indicate that a negative association exists between depression and the availability of moderate-intensity leisure and structured physical activity. Furthermore, a negative association was also found between depression and grip strength in the general population of South Korea aged in individuals over the age of 18