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Silicon catalysts have very low catalytic activity in polyester (PET). However, titanium catalysts have high catalytic activity in polyester. The simultaneous use of titanium and silicon catalysts is effective in reducing the activity of a single titanium catalytic base agent. In addition, the glycol salts of titanium and silicon (Ti-EG and Si-EG) prepared in the present invention for use in the polyester catalytic process can avoid the introduction of other groups of impurities during the polyester catalytic process, which would lead to premature capping of the polyester in the process of polycondensation and chain building and make it difficult to increase the molecular weight, and thus affect the quality of the polyester. It has been verified that the ratio of Ti:Si is 1:1 (mol), and total amount added to the catalyst is 0.15% of the raw material amount, and the polycondensation temperature was 260-280 °C for 60 min. Compared with the single Ti-EG catalyst, the b* value of the synthesized PET was significantly reduced, and the molecular weight and other indexes did not change too much. In addition, at the end of catalysis, the catalyst was uniformly dispersed in the reaction system, which could be used as a matting agent for PET.

ABSTRACT This study was conducted to identify the key volatile compounds that characterize whether silage has deteriorated and to investigate the intrinsic link between the key compounds and silage odor. First, silages with different aerobic exposure durations were sampled, and sensory evaluation integrating aerobic stability monitoring was used to distinguish whether the silage had deteriorated. Subsequently, headspace solid-phase microextraction gas chromatography-mass spectrometry (HS-SPME-GC-MS) was utilized to determine the relative content of the compounds. Using the relative content of the compounds in each silage as input, relative odor activity value (ROAV) calculations and orthogonal partial least squares discriminant analysis (OPLS-DA) were performed to determine the odor contribution of the compounds and the compounds with significant differences in relative content (based on variable importance for the projection, VIP) between the deteriorated and non-deteriorated silages. Next, the key compounds were identified by combining the conditions of average ROAV (aROAV) ≥ 1 and VIP > 1. Finally, the OPLS algorithm was used to analyze the intrinsic link of key compounds with the silage odor. The results showed that three out of 63 compounds—4-ethyl phenol, eugenol, and ethyl linoleate—were key compounds to characterize whether the silages deteriorated or not. In addition, ortho-guaiacol, 4-ethyl guaiacol, and 2-methoxy-4-vinyl phenol were the specific key compounds for deteriorated silage. Eugenol and ethyl linoleate were correlated with fruity, sour, and spicy odors. In addition, guaiacol, 4-ethylphenol, 4-ethyl guaiacol and 2-methoxy-4-vinyl phenol contributed to roasted, musty, and putrid odors.

Este trabajo tiene como objetivo estudiar los verbos introductores de los dos principales procedimientos para citar: el estilo directo (en adelante, ED) y el estilo indirecto (en adelante, EI) en dos lenguas en contraste: español y chino. Para revelar el origen de los verbos introductores, nos basamos en la teoría de los actos de habla y nos damos cuenta de que tienen dos procedencias: el verbo enunciativo, que se halla en la estructura enunciativa implícita “te digo”, y los verbos ilocutivos que poseen el valor realizativo. Las dos fuentes de verbos introductores son iguales tanto en chino como en español. Pero en chino el verbo “decir” 说 (shuō) sufre el proceso de gramaticalización y se transforma en la marca citativa.