BUDDY: molecular formula discovery via bottom-up MS/MS interrogation.

A substantial fraction of metabolic features remains undetermined in mass spectrometry (MS)-based metabolomics, and molecular formula annotation is the starting point for unraveling their chemical identities. Here we present bottom-up tandem MS (MS/MS) interrogation, a method for de novo formula annotation. Our approach prioritizes MS/MS-explainable formula candidates, implements machine-learned ranking and offers false discovery rate estimation. Compared with the mathematically exhaustive formula enumeration, our approach shrinks the formula candidate space by 42.8% on average. Method benchmarking on annotation accuracy was systematically carried out on reference MS/MS libraries and real metabolomics datasets. Applied on 155,321 recurrent unidentified spectra, our approach confidently annotated >5,000 novel molecular formulae absent from chemical databases. Beyond the level of individual metabolic features, we combined bottom-up MS/MS interrogation with global optimization to refine formula annotations while revealing peak interrelationships. This approach allowed the systematic annotation of 37 fatty acid amide molecules in human fecal data. All bioinformatics pipelines are available in a standalone software, BUDDY ( https://github.com/HuanLab/BUDDY ).

The mediating and moderating effects of resilience on the relationship between perceived stress and depression in heroin addicts.

The purpose of this study was to examine the mediating and moderating roles of resilience on the relationship between perceived stress and depression among heroin addicts. A total of 138 heroin addicts completed the measures of perceived stress, resilience, and depression. Correlation analysis indicated that perceived stress was positively associated with depression. Resilience was negatively correlated with perceived stress and depression. Mediation analysis revealed that resilience partially mediated the relationship between perceived stress and depression. However, resilience did not moderate the influence of perceived stress on depression. These findings might provide a better understanding of the mental health among heroin addicts.

The prevalence of anxiety on the empty-nest elders in China.

This study aims to review the pooled prevalence of anxiety disorders among empty-nest elderly in China. Nine studies and 4245 empty-nest elders in China were included in this meta-analysis. A combined effect size with 95 percent confidence intervals was calculated to indicate the magnitude of the effect. The results indicated that the pooled prevalence of anxiety disorders among empty-nest elderly in China was 41.0% (95% confidence interval: 26%-56%). In addition, the different regions in China show different prevalence of anxiety. We speculated that the prevalence varies based on the different methods performed in the empty-nest elderly.

Effect of ethanol pre-fermentation on organic load rate and stability of semi-continuous anaerobic digestion of food waste.

This study investigated the effects of ethanol pre-fermentation on the organic load rate (OLR) and stability of single-phase semi-continuous anaerobic digestion system of food waste. Results revealed that the pre-fermentation group tolerated higher OLR, with a maximum OLR of 5.5 g-VS·L-1·d-1. Moreover, the abundance of microbial community in relation to amino acid degradation in the pre-fermentation group was significantly higher than that in the control group, which made a higher concentration of ammonia nitrogen and caused a stronger system stability and higher alkalinity. Redundancy analysis was performed to explore the factors affecting system instability under high OLR. The instability of control group was found to be significantly influenced by the total volatile fatty acids (TVFA), whereas the pre-fermentation group was affected by total ammonia nitrogen and TVFA. Therefore, if the OLR of the pre-fermentation group is to be further increased, ammonia nitrogen inhibition should also be considered.