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The experiment was to establish an analytical method for the simultaneous determination of 20 kinds of mycotoxins in maize straw feed by QuEChERS-UPLC-MS/MS. The samples were extracted with acetonitrile-acetic acid (95 : 5), and the supernatant was purified by anhydrous MgSO4, PSA and C18. Then an appropriate amount of supernatant was blown to dry with nitrogen. The samples were reconstituted with methanol-water-acetic acid (30 : 70 : 0.1), passed through a PTFE filter membrane, and separated on a C18 chromatographic column. Using the multiple reaction monitoring (MRM) scan mode to monitor the target compounds and the results were quantified by the external standard method. The results showed that the linear ranges of the 20 mycotoxins were good, and the correlation coefficients (R²) were greater than 0.99. The limits of detection were 0.15~3.10 µg/kg, with limits of quantification were 0.49~10.33 µg/kg. The recoveries at the three levels were within the range of 70.4%~118.3%, with relative standard deviations of 1%~10% (n=6). The study indicates that the method was easy to operate, reproducible and highly accurated and sensitive, which can be used for routine screening of mycotoxins in corn stalk feed. [ABSTRACT FROM AUTHOR]

In order to screen and obtain the heat-resistant varieties of sweet potato, four high-quality sweet potato varieties were used as the research objects. The heat resistance evaluation value, SPAD value, hydrogen peroxide (H202) content, malondialdehyde (MDA) content, catalase (CAT) activity and ascorbate peroxidase (APX) activity of leaves were used as the heat resistance indexes. Then, the effects of high temperature stress on the leaf physiology and antioxidant enzyme activity of sweet potatoes were investigated by comparing the differences of various leaf indexes of four varieties of sweet potatoes under the high temperature stress of 35 °C and 40'C. The results showed that there was no significant change in leaf morphology of the four sweet potato varieties under the high temperature stress of 35'C. Under the high temperature stress of 40°C, the leaves of Longshu 116 and Pushu 23 showed obvious water loss curl, and the SPAD value was significantly lower than that of Jinshan 57 and Guangshu 87. The content of H2O2 in leaves was as high as 2.53 nmol ⋅ g-1 and 4. 21 nmol ⋅ g-1, which resulted in the increase of CAT and APX activity, and the content of MDA was significantly higher than that of Jinshan 57 and Guangshu 87, which were up to 10.06 nmol ⋅ g-1 and 14.94 nmol ⋅ g-1. According to the comprehensive evaluation, Guangshu 87 was the best sweet potato variety with excellent heat resistance in the tested varieties, followed by Jinshan 57. The results could provide the heat-resistant variety resources for the planting industry of sweet potato and provide theoretical basis for the breeding of heat-resistant varieties of sweet potato. [ABSTRACT FROM AUTHOR]

Objective: To investigate the clinical value of ultrasound markers in screening fetal trisomy 21., Methods: From Jan. 2001 to Dec. 2011, a retrospective study about sonographic information of 138 fetuses diagnosed as trisomy 21 was taken in the First Affiliated Hospital of Sun Yat-sen University. All fetuses were divided into 3 groups: isolated ultrasound markers, non-isolated ultrasound markers, and isolated structural malformations or other abnormalities. The relationship between trisomy 21 and ultrasound markers as well as structural anomalies or other abnormalities was analyzed., Results: Sonographic anomalies were detected in 132 fetuses (95.7%, 132/138), including ultrasound markers and structural malformations or other abnormalities. One hundred and twenty cases (87.0%, 120/138) had ultrasound markers, 38 (31.7%, 38/120) had one marker and 82 (68.3%, 82/120) had more than one marker (P < 0.01). Fifty-one fetuses (37.0%, 51/138) had isolated ultrasound markers and non-isolated markers were found in 69 fetuses (50.0%, 69/138). Only 12 fetuses (8.7%, 12/138) had isolated structural malformations or other abnormalities. In 20 fetuses on whom the first-trimester ultrasound screening were performed, all had ultrasound markers, 95% (19/20) had thickened nuchal translucency and 55% (11/20) had nasal bone hypoplasia. The most common ultrasound markers on the second-trimester screening were nasal bone hypoplasia, which accounted for 41.9% (52/124) cases, followed by thickened nuchal fold (25.0%, 31/124), short femurs and humerus (24.2%, 30/124), echogenic intracardiac focus (16.1%, 20/124), mild ventriculomegaly (15.3%, 19/124), hyperechoic bowel (12.9%, 16/124), mild renal pyelectasis (12.1%, 15/124). Furthermore, the common structural malformations or other abnormalities were as follows: cardiac defects (33.1%, 41/124), digestive system (26.6%, 33/124)., Conclusions: Ultrasound markers are valuable for screening fetal trisomy 21. The fetuses of trisomy 21 usually had more than one ultrasound markers or associated with other abnormalities. Combinations of ultrasound markers with the results of serum screening and maternal age are necessary for evaluation.

A novel class-specific molecularly imprinted polymer (MIP) beads for sulfonylurea herbicides was synthesized by precipitation polymerization using chlorsulfuron as the template molecule, 2-(diethylamino) ethyl methacrylate (DEAEMA) as the functional monomer, and trimethylolpropane trimethacrylate (TRIM) as the cross-linker. The mechanisms of recognition of MIP beads to the template molecule were evaluated by UV-spectrum and FTIR in the choosing and optimizing polymerization system experiment. The results showed that MIP beads contained the group which could interact with template molecule and its analogue by the hydrogen bonding specifically.