Xylitol is a five-carbon sugar alcohol with established commercial use as an alternative sweetener and can be produced from hemicellulose hydrolysate. However, there are difficulties with microbiological growth and xylitol biosynthesis on hydrolysate because of the inhibitors formed from hydrolysis of hemicellulose. This research focused on the effect of furfural, vanillin, and syringaldehyde on growth of Candida guilliermondii and xylitol accumulation from xylose in a semi-synthetic medium in microwell plate and bioreactor cultivations. All three compounds reduced specific growth rate, increased lag time, and reduced xylitol production rate. In general, increasing concentration of inhibitor increased the severity of inhibition, except in the case of 0.5 g vanillin per liter, which resulted in a faster late batch phase growth rate and increased biomass yield. At concentrations of 1 g/l or higher, furfural was the least inhibitory to growth, followed by syringaldehyde. Vanillin most severely reduced specific growth rate. All three inhibitors reduced xylitol production rate approximately to the same degree.
As coronavirus disease 2019 swept through mainland China, students were forced to quickly switch to learning online. This study aimed to capture college Chinese English as a Second/Foreign Language (ESL/EFL) learners’ perceptions of rapidly switching to online learning at two colleges in China’s southern Guangdong Province. A bilingual (Chinese/English) online survey was used to collect data. The participants ( n = 504) responded to a survey about their feelings and perceptions of sudden online learning, a term the authors call “learning whiplash.” We asked students about how much they liked online at the beginning of learning online, how long students have been taking online courses, and how many online courses the students were currently taking. We also asked about the students’ perceptions of the quality of online learning when compared to physical learning. Finally, we asked students about getting drowsy and/or falling asleep during their online classes. We found that students were taking on average five to seven online courses and that they did not like learning online early in the epidemic. Our study confirmed that students preferred a hybrid learning environment. Seventy-nine percent of students admitted to getting drowsy and/or falling asleep during their online classes. Specific suggestions are given for teachers to keep students active and engaged in online learning. Practical guidance and strategies for creating vibrant online learning environments are provided. This research informs both the communities on online and e-learning as well as ESL/EFL teaching.
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