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Wang, Yi,Wang, Chen,Chen, Yonglun,Cui, MingYu,Wang, Qiong,Guo, Peng The Korean Society for Microbiology and Biotechnol 2022 Journal of microbiology and biotechnology Vol.32 No.6
α-Galactosidase is a debranching enzyme widely used in the food, feed, paper, and pharmaceuticals industries and plays an important role in hemicellulose degradation. Here, T26, an aerobic bacterial strain with thermostable α-galactosidase activity, was isolated from laboratory-preserved lignocellulolytic microbial consortium TMC7, and identified as Parageobacillus thermoglucosidasius. The α-galactosidase, called T26GAL and derived from the T26 culture supernatant, exhibited a maximum enzyme activity of 0.4976 IU/ml when cultured at 60℃ and 180 rpm for 2 days. Bioinformatics analysis revealed that the α-galactosidase T26GAL belongs to the GH36 family. Subsequently, the pET-26 vector was used for the heterologous expression of the T26 α-galactosidase gene in Escherichia coli BL21 (DE3). The optimum pH for α-galactosidase T26GAL was determined to be 8.0, while the optimum temperature was 60℃. In addition, T26GAL demonstrated a remarkable thermostability with more than 93% enzyme activity, even at a high temperature of 90℃. Furthermore, Ca<sup>2+</sup> and Mg<sup>2+</sup> promoted the activity of T26GAL while Zn<sup>2+</sup> and Cu<sup>2+</sup> inhibited it. The substrate specificity studies revealed that T26GAL efficiently degraded raffinose, stachyose, and guar gum, but not locust bean gum. This study thus facilitated the discovery of an effective heat-resistant α-galactosidase with potent industrial application. Meanwhile, as part of our research on lignocellulose degradation by a microbial consortium, the present work provides an important basis for encouraging further investigation into this enzyme complex.
Qiong Li,Songqi Ma,Jingjing Wei,Sheng Wang,Xiwei Xu,Kaifeng Huang,Binbo Wang,Wangchao Yuan,Jin Zhu 한국고분자학회 2020 Macromolecular Research Vol.28 No.5
Non-planar-ring epoxies together with non-planar-ring hardeners could achieve thermosets combining ultra-high shape recovery speed and excellent thermal properties. High shape recovery speed reflected high efficiency, and could decrease the energy consumption and the harmful effect of external stimuli on the materials, while it often conflicts with the thermal properties of shape memory polymers. In this paper, for the first time, epoxy resins with the super-short shape recovery time within 3 s were developed from non-planar-ring epoxies and hardeners, and their glass transition temperature (T g) were ~127 °C much higher than their benzene ring analogues. The effects of non-planar-ring structures of the epoxies and hardeners on the curing behavior, thermal properties as well as the shape memory properties of the thermosets were systematically investigated; the structure-property relationships were disclosed with the help of computational simulation of structure parameters and ESP maps. The faster shape recovery speed of the non-planar-ring epoxy thermosets is from their higher molecular mobility contributed by the conformational transition of non-planar-rings as well as their higher recovery force compared with benzene ring analogs. Their higher T gs are from the steric hindrance by the larger molecular volume of the non-planar-rings than benzene ring. This work will provide an effective method to produce shape memory polymers with excellent shape memory effects and high performance.
Grafting sulfated zirconia on mesoporous silica
Wang, Yong,Lee, Kwan-Young,Choi, Saemin,Liu, Jun,Wang, Li-Qiong,Peden, Charles H. F. Royal Society of Chemistry 2007 Green chemistry Vol.9 No.6
<P>Recently, sulfated zirconia has received considerable attention as a potential solid acid catalyst to replace problematic homogeneous acid catalysts. In this paper, the preparation and properties of acid catalysts obtained by grafting ziconia with atomic precision on MCM-41 mesoporous silica were studied. TEM and potential titration characterizations revealed that ZrO<SUB>2</SUB>/MCM-41 with monolayer coverage can be obtained using this grafting technique. Sulfated ZrO<SUB>2</SUB>/MCM-41 exhibits improved thermal stability than that of bulk sulfated zirconia, as evidenced by temperature programmed characterizations and XRD analysis. Temperature programmed reaction of isopropanol was used to evaluate the acidity of sulfated ZrO<SUB>2</SUB>/MCM-41. It was found that the acid strength of sulfated ZrO<SUB>2</SUB>/MCM-41 with monolayer coverage is weaker than bulk sulfated zirconia but stronger than SiO<SUB>2</SUB>–Al<SUB>2</SUB>O<SUB>3</SUB>, a common strong acid catalyst.</P> <P>Graphic Abstract</P><P>Sulfated zirconia solid acid catalysts were prepared by grafting zirconium oxide on mesoporous silica with layer-by-layer coverage, followed by depositing sulfate groups on the surface. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=b614928f'> </P>
Qiong Wang,Jin-Hwa Lee 한국영어어문교육학회 2014 영어어문교육 Vol.20 No.3
This study investigated what advanced-level EFL learners pay attention to while planning and performing a speaking task, and how this cognitive process affects their subsequent task performance. A total of 21 English-major college students performed an oral presentation task after provided with 10-minute planning time. Their task performances were analyzed in terms of fluency, complexity and accuracy. Furthermore, in order to investigate the participants’ attentional allocation during task planning as well as task performance, retrospective interviews were conducted right after task performance. The analyses of the data showed that the learners placed most attention to conceptualization of ideas during pre-task planning and to fluency of speech while performing a task. On the other hand, little attention was paid to formulizing utterances and pursuing complexity and accuracy. It was also found that the learners’ attention to fluency, complexity or accuracy during task planning did not always lead to successful performance in the aspect. While speech rate and lexical diversity were more susceptible to attentional control, accuracy and syntactic complexity were not much affected by learners’ planning in advance. The findings are discussed in relation to the roles and limitations of pre-task planning in L2 performance and pedagogical implications.