Vitamin A deficiency has become a worldwide problem.Biofortified foods can potentially be an inexpensive,locally adaptable,and long-term solution to dietary-nutrient deficiency.In order to improve theβ-carotene conte...Vitamin A deficiency has become a worldwide problem.Biofortified foods can potentially be an inexpensive,locally adaptable,and long-term solution to dietary-nutrient deficiency.In order to improve theβ-carotene content in maize grain by breeding and minimize vitamin A deficiency,a complete diallel cross was designed with eight inbred lines of maize,and 64 combinations were obtained in this study.The experimental combinations were planted in Yunnan and Sichuan provinces,respectively,with a random complete block design.Theβ-carotene contents in the grains of the experimental materials were analyzed by high-performance liquid chromatography.Among the tested materials,the effect difference of general combining ability of theβ-carotene content was significant;however,the effect difference of the special combining ability and the reciprocal effect were not significant.Theβ-carotene content of maize grain was not influenced significantly by the cross and the reciprocal cross.There was a significant correlation about theβ-carotene content in the maize grains between the F 1 and their parents.The combinations with highβ-carotene content were obviously influenced by the environment,and the mean value ofβ-carotene content for the experimental materials planted in Ya'an of Sichuan was higher than that planted in Yuanjiang of Yunnan,with the results being significant at the 0.01 level.展开更多
GeTe_(4) films are deposited by using a dc magnetron sputtering technique, and its structural, thermal and electrical properties are investigated systematically. The prototypical phase-change memory cells are fabricat...GeTe_(4) films are deposited by using a dc magnetron sputtering technique, and its structural, thermal and electrical properties are investigated systematically. The prototypical phase-change memory cells are fabricated by using a focused ion beam and magnetron sputtering techniques. Compared with Ge_(2)Sb_(2)Te_(5), the GeTe_(4) film exhibits a higher crystallization temperature (235℃), better data retention of ten years at 129℃, and larger activation energy (2.94 eV). GeTe4 phase change memory cells with an effective diameter of 1 μm show proper switching speed, low power consumption, and good resistance contrast. The Set and Reset operations are achieved by using a 200-ns 2.0-V pulse and a 30-ns 3.0-V pulse, respectively. The dynamic switching ratio between the OFF and ON states is larger than 1×10^(4).展开更多
全氟及多氟化合物(perfluoroalkyl and polyfluoroalkyl substances,PFASs)因其环境持久性、生物累积性、疏水疏油性及化学稳定性,被广泛应用于工业生产和日常生活。然而,这些化合物的广泛存在对生态环境和人类健康构成了严重威胁,尤其...全氟及多氟化合物(perfluoroalkyl and polyfluoroalkyl substances,PFASs)因其环境持久性、生物累积性、疏水疏油性及化学稳定性,被广泛应用于工业生产和日常生活。然而,这些化合物的广泛存在对生态环境和人类健康构成了严重威胁,尤其是通过动物源性食品(如鱼类、贝类、家禽及其加工产品等)的膳食摄入,是人类暴露于PFASs的主要途径之一。为有效评估其健康风险并制定相关监管政策,建立快速、高效、灵敏的检测方法以监测动物源性食品中的PFASs污染水平至关重要。本文系统综述了动物源性食品中PFASs的样品前处理方法,并重点探讨了色谱技术及色谱-质谱联用技术在检测中的应用进展。进一步总结了不同基质的动物源性食品中PFASs污染水平的研究现状,为环境污染评估、食品安全监管及检测技术的优化提供了重要参考。展开更多
基金supported by the Harvest-Plus China Program,the National High-Tech R&D Program of China(2011AA10A103)the Sichuan Maize Breeding Program in the 12th Five-Year Plan,China
文摘Vitamin A deficiency has become a worldwide problem.Biofortified foods can potentially be an inexpensive,locally adaptable,and long-term solution to dietary-nutrient deficiency.In order to improve theβ-carotene content in maize grain by breeding and minimize vitamin A deficiency,a complete diallel cross was designed with eight inbred lines of maize,and 64 combinations were obtained in this study.The experimental combinations were planted in Yunnan and Sichuan provinces,respectively,with a random complete block design.Theβ-carotene contents in the grains of the experimental materials were analyzed by high-performance liquid chromatography.Among the tested materials,the effect difference of general combining ability of theβ-carotene content was significant;however,the effect difference of the special combining ability and the reciprocal effect were not significant.Theβ-carotene content of maize grain was not influenced significantly by the cross and the reciprocal cross.There was a significant correlation about theβ-carotene content in the maize grains between the F 1 and their parents.The combinations with highβ-carotene content were obviously influenced by the environment,and the mean value ofβ-carotene content for the experimental materials planted in Ya'an of Sichuan was higher than that planted in Yuanjiang of Yunnan,with the results being significant at the 0.01 level.
基金the National Natural Science Foundation of China under Grant Nos 51072078 and 61076008the National Basic Research Program of China under Grant No 2010CB630704the College Graduate Research and Innovation Project of Jiangsu Province under Grant No CXZZ12_0050.
文摘GeTe_(4) films are deposited by using a dc magnetron sputtering technique, and its structural, thermal and electrical properties are investigated systematically. The prototypical phase-change memory cells are fabricated by using a focused ion beam and magnetron sputtering techniques. Compared with Ge_(2)Sb_(2)Te_(5), the GeTe_(4) film exhibits a higher crystallization temperature (235℃), better data retention of ten years at 129℃, and larger activation energy (2.94 eV). GeTe4 phase change memory cells with an effective diameter of 1 μm show proper switching speed, low power consumption, and good resistance contrast. The Set and Reset operations are achieved by using a 200-ns 2.0-V pulse and a 30-ns 3.0-V pulse, respectively. The dynamic switching ratio between the OFF and ON states is larger than 1×10^(4).
文摘全氟及多氟化合物(perfluoroalkyl and polyfluoroalkyl substances,PFASs)因其环境持久性、生物累积性、疏水疏油性及化学稳定性,被广泛应用于工业生产和日常生活。然而,这些化合物的广泛存在对生态环境和人类健康构成了严重威胁,尤其是通过动物源性食品(如鱼类、贝类、家禽及其加工产品等)的膳食摄入,是人类暴露于PFASs的主要途径之一。为有效评估其健康风险并制定相关监管政策,建立快速、高效、灵敏的检测方法以监测动物源性食品中的PFASs污染水平至关重要。本文系统综述了动物源性食品中PFASs的样品前处理方法,并重点探讨了色谱技术及色谱-质谱联用技术在检测中的应用进展。进一步总结了不同基质的动物源性食品中PFASs污染水平的研究现状,为环境污染评估、食品安全监管及检测技术的优化提供了重要参考。
文摘目的:分析新生儿入院时发生低体温的危险因素,为预防及干预提供借鉴。方法:检索国内外数据库中与新生儿入院低体温影响因素相关的队列研究、病例对照研究以及横断面研究,检索时限为数据库建库至2025年2月28日。采用RevMan 5.4进行Meta分析,计算并分析各影响因素合并OR值。结果:共纳入3篇病例对照研究、7篇队列研究和2篇横断面研究进行系统评价,其中低体温组7 096例,非低体温组4 367例。Meta分析结果显示,影响新生儿入院低体温发生情况的影响因素主要有5 min Apgar评分≥7分(OR=0.57)、产前使用糖皮质激素(OR=0.47)、出生体重<2 500 g(OR=3.61)、复苏史(OR=3.14)、剖宫产(OR=1.39),延迟开奶(OR=2.79)、窒息史(OR=3.97)、1 min Apgar评分≥7分(OR=0.48)、多胎(OR=1.67)、母亲产科并发症史(OR=5.26)、转运季节为寒冷季节(OR=2.31)。结论:新生儿入院低体温的发生受多因素影响,应对入院新生儿采取各种有针对性的预防措施,以减少新生儿入院低体温的发生。
