Photoionization and dissociation of the 1-propanol dimer and subsequent fragmentations have been investigated by synchrotron vacuum ultraviolet (VUV) photoionization mass spectrometry and theoretical calculations. Besides the protonated monomer cation (C3H7OH)·H(+) (m/z = 61) and Cα-Cβ bond cleavage fragment CH2O·(C3H7OH)H(+) (m/z = 91), the measured mass spectrum at an incident photon energy of 13 eV suggests a new dissociation channel resulting in the formation of the (C3H7OH)·H(+)·(C2H5OH) (m/z = 107) fragment. The appearance energies of the fragments (C3H7OH)·H(+), CH2O·(C3H7OH)H(+) and (C3H7OH)·H(+)·(C2H5OH) are measured at 10.05 ± 0.05 eV, 9.48 ± 0.05 eV, and 12.8 ± 0.1 eV, respectively, by scanning photoionization efficiency (PIE) spectra. The 1-propanol ion fragments as a function of VUV photon energy were interpreted with the aid of theoretical calculations. In addition to O-H and Cα-Cβ bond cleavage, a new dissociation channel related to Cβ-Cγ bond cleavage opens. In this channel, molecular rearrangement (proton transfer and hydrogen transfer after surmounting an energy barrier) gives rise to the generated complex, which then dissociates to produce the mixed propanol/ethanol proton bound cation (C3H7OH)·H(+)·(C2H5OH). This new dissociation channel has not been reported in previous studies of ethanol and acetic acid dimers. The photoionization and dissociation processes of the 1-propanol dimer are described in the photon energy range of 9-15 eV.
Objective
Several previous studies have suggested oral diseases was correlated to Inflammatory bowel disease (IBD), Crohn's disease (CD) and ulcerative colitis (UC), but the causality and direction of action remained largely unclear. Therefore, this study will through a bidirectional two-sample Mendelian randomization (MR) based on the oral-gut axis to explore evidence for oral diseases with IBD and its two main subtypes.
Methods
We sourced summary statistics from the GWAS database on four oral diseases with each of the three IBD databases for exposure-outcome by bidirectional MR. The MR analyses were performed using IVW as the main effect estimate measure and a series of sensitivity analyses and potential heterogeneity tests were applied to make the results more reliable. And then, we chose either a random-effects model or a fixed-effects model for the meta-analysis based on the presence or absence of heterogeneity thereby.
Results
From oral diseases to IBD, we found a significant effect of genetically predict lichen planus on IBD [OR: 1.069; 95%CI: 1.043–1.097; P < 0.01], CD [OR: 1.090; 95%CI: 1.056–1.125; P < 0.01] and UC [OR: 1.075; 95%CI: 1.040–1.111; P < 0.01]. From IBD to oral diseases, we found a positive effect of whole IBD on periodontal disease [OR: 1.051; 95%CI: 1.020–1.083; P < 0.01], lichen planus [OR: 1.166; 95%CI: 1.011–1.344; P = 0.04] and oral ulcer [OR: 1.003; 95%CI: 1.001–1.004; P < 0.01]. In subtype analysis, we found a suggestive association between UC and periodontal disease [OR: 1.043; 95%CI: 1.009–1.077; P = 0.01], as well as a significant effect of CD on lichen planus [OR: 1.088; 95%CI: 1.038–1.141; P < 0.01].
Conclusion
Our study provides modest evidence for a causal effect between oral diseases and IBD, which can help guide clinical treatment and decision-making for the oral health of patients with IBD, and also somewhat supports the clinical need to predict the extent of IBD disease activity in patients with oral problems.
Wide and abusive applications of fungicides (such as chlorothalonil) in agricultural production have caused various adverse effects on the environment, especially on the soil. Herein, a novel laser desorption VUV single photon postionization mass spectrometry (LDPI-MS) has been firstly applied to the direct and fast detection of chlorothalonil in soil. In the experiment, three different wavelength lasers were used as the ionization sources (SPI at 118 nm, REMPI at 266 nm and 355 nm) and the results showed that only SPI at 118 nm could achieve expected "soft" ionization. The limit of detection in 118 nm ionization was determined to be 0.5 pmol per spot, ca. 1 mg/kg of chlorothalonil in soil. Moreover, no other additives were needed to assistant desorption/evaporation of chlorothalonil from soil samples and the detecting process could be rapidly completed on the basis of a time-saving sample pretreatment. The results demonstrated that LDPI-MS method held a great potential for detecting real natural soil contaminated with chlorothalonil.
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