69 research outputs found
Cultivation of Core Competences of English Major Students under the Inter-discinplinary Guidance A Case Study of “The Survey of British and American Culture” Course
The newly issued National Standards by the Ministry of National Education for the Quality of Foreign Language and Literature Teaching (hereinafter referred to as the “National Standards”) clearly points out that the curriculum system of foreign language majors should emphasize the cultivation of competences and the construction of professional knowledge, especially the cultivation of cross-cultural, critical, and innovative abilities. Therefore, in order to enhance college students’ autonomous study ability and cross-cultural skills, this study, based on the concepts of content and language integration, aims to explore the way to combine Willis’ outline of procedure for task-based learning with the five principles of intercultural teaching, and utilize task-based teaching method, and rely on the course—“British and American Culture: A Course to Develop Critical Thinking from a cross-cultural perspective” to respectively consider the design of autonomous study worksheets for English majors before, during, and after class, so as to improve their autonomous learning ability, cultural critical thinking and intercultural communication skills. It will be helpful for the implementation of similar courses
Interactive Effects of Water and Fertilizer on Yield, Soil Water and Nitrate Dynamics of Young Apple Tree in Semiarid Region of Northwest China
Exploring the interactive effect of water and fertilizer on yield, soil water and nitrate dynamics of young apple tree is of great importance to improve the management of irrigation and fertilization in the apple-growing region of semiarid northwest China. A two-year pot experiment was conducted in a mobile rainproof shelter of the water-saving irrigation experimental station in Northwest A&F University, and the investigation evaluated the response of soil water and fertilizer migration, crop water productivity (CWP), irrigation water use efficiency (IWUE), partial factor productivity (PFP) of young apple tree to different water and fertilizer regimes (four levels of soil water: 75%–85%, 65%–75%, 55%–65% and 45%–55% of field capacity, designated W1, W2, W3 and W4, respectively; three levels of N-P2O5-K2O fertilizer, 30-30-10, 20-20-10 and 10-10-10 g plant−1, designated F1, F2 and F3, respectively). Results showed that F1W1, F2W1 and F3W1 had the highest average soil water content at 0~90 cm compared with the other treatments. When fertilizer level was fixed, the average soil water content was gradually increased with increasing irrigation amount. For W1, W2, W3 and W4, high levels of water content were mainly distributed at 50~80 cm, 40~70 cm, 30~50 cm and 10~30 cm, respectively. There was no significant difference in soil water content at all fertilizer treatments. However, F1 and F2 significantly increased soil nitrate-N content by 146.3%~246.4% and 75.3%~151.5% compared with F3. The highest yield appeared at F1W1 treatment, but there was little difference between F1W1 and F2W2 treatment. F2W2treatment decreased yield by 7.5%, but increased IWUE by 11.2% compared with F1W1 treatment. Meanwhile, the highest CWP appeared at F2W2 treatment in the two years. Thus, F2W2 treatment (soil moisture was controlled in 65–75% of field capacity, N-P2O5-K2O were controlled at 20-20-10 g·tree−1) reached the best water and fertilizer coupling mode and it was the optimum combinations of water and fertilizer saving
Controlled Release of Biological Control Agents for Preventing Aflatoxin Contamination from Starch–Alginate Beads
For the wise use of fungal biocontrol and metalaxyl fungicide, starch–alginate-based formulations have been developed by encapsulating metalaxyl and non-toxigenic Aspergillus flavus spores simultaneously in the form of microspheres using calcium chloride as a cross-linking agent. The formulations were characterized by Fourier transform infrared spectroscopy (FTIR), a scanning electron micrograph (SEM), and thermogravimetry (TGA). Formulation characteristics, including the bead size, entrapment efficiency, swelling ratio of the beads, and rheological properties, were analyzed. The release behavior of beads with different formulations was evaluated. The addition of kaolin and rice husk powder in starch–alginate beads retarded the release profile of spores and metalaxyl. The release of the active ingredient from starch–alginate–kaolin beads and starch–alginate–rice husk powder beads occurred in both a controlled and sustained manner. Additionally, the release rate decreased with the increase of kaolin or rice husk powder content. The beads added with kaolin were slower than the release of rice husk powder. In comparison, spores released slower and lasted longer than metalaxyl. The starch–alginate–kaolin formulations could be used as controlled release material in the field of biocontrol and reduce the harm of fungicides to the environment
Anaerobic Co-Digestion Scheme of Biogas Engineering Based on Feedstock and Temperature
This article investigates the current status and distribution of the feedstock of biogas engineering in China, evaluates the temperature conditions for anaerobic co-digestion (AcoD), and assesses the biogas production potential of feedstock in AcoD, including six feedstocks, namely, maize straw (M), wheat straw (W), rice straw (R), pig manure (P), cow manure (C), and sheep manure (S). The total amount of M, W, and R was 3.89 × 108, 2.10 × 108, and 1.50 × 108 tons, respectively, and that of P, C, and S was 8.46 × 108, 1.31 × 109, and 4.95 × 108 tons, respectively. However, the spatial distributions and amount of those resources were found to be uneven in China. Heilongjiang has abundant maize straw, and Henan has abundant wheat resources. Sichuan is rich in cow manure, while Inner Mongolia is rich in sheep manure. The analysis of total biogas production (TBP) by mono-digestion and co-digestion (using two feedstocks at ratio of 1:9, 3:7, 5:5, 7:3 and 9:1) showed that co-digestion outperforms mono-digestion under 15 and 25 °C. Thus, it is necessary to study anaerobic co-digestion scheme (AcoDS), which will provide a reference for biogas engineering in different regions to promote the biogas yield based on their actual situation
Quality Evaluation of Potentilla fruticosa L. by High Performance Liquid Chromatography Fingerprinting Associated with Chemometric Methods.
The present study was performed to assess the quality of Potentilla fruticosa L. sampled from distinct regions of China using high performance liquid chromatography (HPLC) fingerprinting coupled with a suite of chemometric methods. For this quantitative analysis, the main active phytochemical compositions and the antioxidant activity in P. fruticosa were also investigated. Considering the high percentages and antioxidant activities of phytochemicals, P. fruticosa samples from Kangding, Sichuan were selected as the most valuable raw materials. Similarity analysis (SA) of HPLC fingerprints, hierarchical cluster analysis (HCA), principle component analysis (PCA), and discriminant analysis (DA) were further employed to provide accurate classification and quality estimates of P. fruticosa. Two principal components (PCs) were collected by PCA. PC1 separated samples from Kangding, Sichuan, capturing 57.64% of the variance, whereas PC2 contributed to further separation, capturing 18.97% of the variance. Two kinds of discriminant functions with a 100% discrimination ratio were constructed. The results strongly supported the conclusion that the eight samples from different regions were clustered into three major groups, corresponding with their morphological classification, for which HPLC analysis confirmed the considerable variation in phytochemical compositions and that P. fruticosa samples from Kangding, Sichuan were of high quality. The results of SA, HCA, PCA, and DA were in agreement and performed well for the quality assessment of P. fruticosa. Consequently, HPLC fingerprinting coupled with chemometric techniques provides a highly flexible and reliable method for the quality evaluation of traditional Chinese medicines
Genetic Diversity and Structure of <i>Sinopodophyllum hexandrum</i> (Royle) Ying in the Qinling Mountains, China
<div><p><i>Sinopodophyllum hexandrum</i> is an important medicinal plant whose genetic diversity must be conserved because it is endangered. The Qinling Mts. are a <i>S. hexandrum</i> distribution area that has unique environmental features that highly affect the evolution of the species. To provide the reference data for evolutionary and conservation studies, the genetic diversity and population structure of <i>S. hexandrum</i> in its overall natural distribution areas in the Qinling Mts. were investigated through inter-simple sequence repeats analysis of 32 natural populations. The 11 selected primers generated a total of 135 polymorphic bands. <i>S. hexandrum</i> genetic diversity was low within populations (average H<sub>e</sub> = 0.0621), but higher at the species level (H<sub>e</sub> = 0.1434). Clear structure and high genetic differentiation among populations were detected by using the unweighted pair group method for arithmetic averages, principle coordinate analysis and Bayesian clustering. The clustering approaches supported a division of the 32 populations into three major groups, for which analysis of molecular variance confirmed significant variation (63.27%) among populations. The genetic differentiation may have been attributed to the limited gene flow (N<sub>m</sub> = 0.3587) in the species. Isolation by distance among populations was determined by comparing genetic distance versus geographic distance by using the Mantel test. Result was insignificant (<i>r</i> = 0.212, <i>P</i> = 0.287) at 0.05, showing that their spatial pattern and geographic locations are not correlated. Given the low within-population genetic diversity, high differentiation among populations and the increasing anthropogenic pressure on the species, in situ conservation measures were recommended to preserve <i>S. hexandrum</i> in Qinling Mts., and other populations must be sampled to retain as much genetic diversity of the species to achieve ex situ preservation as a supplement to in situ conservation.</p></div
Thermosensitive Hydrogel for Encapsulation and Controlled Release of Biocontrol Agents to Prevent Peanut Aflatoxin Contamination
Starch, alginate, and poly(N-isopropylacrylamide) (PNIPAAm) were combined to prepare a semi-interpenetrating network (IPN) hydrogel with temperature sensitivity. Calcium chloride was used as cross-linking agent, the non-toxigenic Aspergillus flavus spores were successfully encapsulated as biocontrol agents by the method of ionic gelation. Characterization of the hydrogel was performed by Fourier-transform infrared spectroscopy (FTIR), scanning electron micrograph (SEM), and thermogravimetry analysis (TGA). Formulation characteristics, such as entrapment efficiency, beads size, swelling behavior, and rheological properties were evaluated. The optical and rheological measurements indicated that the lower critical solution temperature (LCST) of the samples was about 29–30 °C. TGA results demonstrated that the addition of kaolin could improve the thermal stability of the semi-IPN hydrogel. Morphological analysis showed a porous honeycomb structure on the surface of the beads. According to the release properties of the beads, the semi-IPN hydrogel beads containing kaolin not only have the effect of slow release before peanut flowering, but they also can rapidly release biocontrol agents after flowering begins. The early flowering stage of the peanut is the critical moment to apply biocontrol agents. Temperature-sensitive hydrogel beads containing kaolin could be considered as carriers of biocontrol agents for the control of aflatoxin in peanuts
Isolation and characterization of Pseudomonas sp DX7 capable of degrading sulfadoxine
Given that the intensive application of sulfonamides in aquaculture, animal husbandry and malaria treatment has lead to an increase in sulfonamide discharge into the environment, there is an increasing need to find a way to remediate sulfonamide-contaminated sites. The bacterial strain DX7 was isolated from a marine environment and is capable of degrading sulfadoxine. DX7 was identified as a Pseudomonas sp. based on 16S rRNA gene sequencing. Approximately 30% of sulfadoxine was degraded after Pseudomonas sp. DX7 was inoculated into mineral salt plus tryptone media containing 10 mg l(-1) sulfadoxine for 2 days. The degradation efficiency under different environmental conditions was characterized using HPLC. The optimal temperature and pH for sulfadoxine biodegradation were around 30A degrees C and 6.0, respectively. The optimal concentrations of sulfadoxine and tryptone for sulfadoxine biodegradation were determined to be approximately 30 mg l(-1) and between 2.0 and 8.0 g l(-1), respectively. Cytotoxicity analysis indicated that the metabolites of sulfadoxine generated by Pseudomonas sp. DX7 showed significantly reduced cytotoxicity to Hela cells. These results suggest that Pseudomonas sp. DX7 is a new bacterial resource for degrading sulfadoxine and indicate the potential of the isolated strain in the bioremediation of sulfadoxine-contaminated environments.Given that the intensive application of sulfonamides in aquaculture, animal husbandry and malaria treatment has lead to an increase in sulfonamide discharge into the environment, there is an increasing need to find a way to remediate sulfonamide-contaminated sites. The bacterial strain DX7 was isolated from a marine environment and is capable of degrading sulfadoxine. DX7 was identified as a Pseudomonas sp. based on 16S rRNA gene sequencing. Approximately 30% of sulfadoxine was degraded after Pseudomonas sp. DX7 was inoculated into mineral salt plus tryptone media containing 10 mg l(-1) sulfadoxine for 2 days. The degradation efficiency under different environmental conditions was characterized using HPLC. The optimal temperature and pH for sulfadoxine biodegradation were around 30A degrees C and 6.0, respectively. The optimal concentrations of sulfadoxine and tryptone for sulfadoxine biodegradation were determined to be approximately 30 mg l(-1) and between 2.0 and 8.0 g l(-1), respectively. Cytotoxicity analysis indicated that the metabolites of sulfadoxine generated by Pseudomonas sp. DX7 showed significantly reduced cytotoxicity to Hela cells. These results suggest that Pseudomonas sp. DX7 is a new bacterial resource for degrading sulfadoxine and indicate the potential of the isolated strain in the bioremediation of sulfadoxine-contaminated environments
Descriptive statistics summary of the <i>S. hexandrum</i> populations.
<p><b>Note</b>: A<sub>o</sub>, observed number of alleles per locus; A<sub>e</sub>, effective number of alleles per locus; He, Nei’s gene diversity; H<sub>o</sub>, Shannon’s information index; PPB, percentage of polymorphic bands.</p><p>Descriptive statistics summary of the <i>S. hexandrum</i> populations.</p
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