Enantioselective One‐Pot Reaction: Organocatalyzed Synthesis of Fully Functionalized Oxabicyclo[2.2.2]octanes with Seven Contiguous Stereocenters

An enantioselective one‐pot Michael/Michael/Henry/hemiacetalization reaction between α,β‐unsaturated aldehydes, α‐ketoamides, and nitroalkenes under mild conditions catalyzed by a diarylprolinol silyl ether has been developed. The sequential methodology provides a direct approach to a wide range of fully substituted chiral oxabicyclo[2.2.2]octanes with seven contiguous stereocenters in moderate to excellent yields (up to 99%), high to excellent diastereoselectivities (up to >25:1 dr), and high to excellent enantioselectivities (up to 99% ee).

     

Exposure to Diflubenzuron Results in an Up-Regulation of a Chitin Synthase 1 Gene in Citrus Red Mite,Panonychus citri (Acari: Tetranychidae)

Chitin synthase synthesizes chitin, which is critical for the arthropod exoskeleton. In this study, we cloned the cDNA sequences of a chitin synthase 1 gene, PcCHS1, in the citrus red mite, Panonychus citri (McGregor), which is one of the most economically important pests of citrus worldwide. The full-length cDNA of PcCHS1 contains an open reading frame of 4605 bp of nucleotides, which encodes a protein of 1535 amino acid residues with a predicted molecular mass of 175.0 kDa. A phylogenetic analysis showed that PcCHS1 was most closely related to CHS1 from Tetranychus urticae. During P. citri development, PcCHS1 was constantly expressed in all stages but highly expressed in the egg stage (114.8-fold higher than in the adult). When larvae were exposed to diflubenzuron (DFB) for 6 h, the mite had a significantly high mortality rate, and the mRNA expression levels of PcCHS1 were significantly enhanced. These results indicate a promising use of DFB to control P. citri, by possibly acting as an inhibitor in chitin synthesis as indicated by the up-regulation of PcCHS1 after exposure to DFB.     

Preface

Evolutionary Algorithms(EAs)mimicking the principles of natural evolution can be used as powerful search and optimization methods.These Evolutionary Optimization methods are superior to traditional optimization methods especially in situations where gradient information is not readily available.EAs are generic and robust optimization methods since they do not make any assumption about the underlying search space.This is clearly evident by the success of EAs in a diverse range of real-world applications.T...     

铽-樟脑酸-α,α'联吡啶配合物的合成及荧光性能研究

合成了稀土铽-α,α'联吡啶三元配合物,通过元素分析、红外光谱分析,确定了配合物的组成为Tb2(CA)3(dipy)2(CA:樟脑酸根,dipy:α,α'联吡啶),另外,又合成了不同比例铽、钇异核混配三元配合物.在室温下测定了配合物的荧光激发光谱,最佳波长为313 nm,即在313.0 nm光的激发下,测定了四种稀土配合物的发射光谱,发射光谱图显示了Tb3 离子的特征光谱,产生四条谱线,分别是5D4-7F6(490.0 nm)5D4-7F5(544.0 nm),5D4-7F4(584.0 nm),5D4-7F3(620.0nm),最强峰为544 nm处Tb3 离子绿色荧光发射峰.对四种配合物荧光发射峰强度变化的研究表明,钇的掺入并没有降低铽离子的荧光强度,说明不发光稀土离子钇对铽离子的荧光发射有敏化作用.     

基于Midas/Gen的超高建造爬升模架设备建模方法及工程应用

以液压爬升模架和整体钢平台模架为典型代表的爬升模架设备在超高层建筑建造中发挥了关键作用。针对目前爬升模架设备计算分析建模效率低的问题,介绍了一种基于Midas/Gen mgt文件的交互式建模方法。首先对目前爬升模架设备计算分析两种常规建模方法进行了介绍。其次介绍了mgt命令和mgt文件的交互式建模方法,重点对mgt命令建模的框架和格式进行了分析。最后结合实际超高层工程验证了本文方法的有效性,工程应用表明该方法能够大幅度提升建模效率且能应用于精细化计算分析。     

纳米SiO2抑制PVC中增塑剂DOP迁移的研究

实验通过添加纳米粒子SiO2,研究抑制软质聚氯乙烯(PVC)中增塑剂邻苯二甲酸二辛脂(DOP)迁移规律,评价PVC样品溶剂抽出率,对挥发损失率、拉伸性能和邵氏硬度的测定分析,得出以下结论:纳米粒子SiO2可以抑制软质PVC中DOP的迁移。用正己烷浸泡PVC样品,随浸泡时间的延长,溶剂抽出率增大;随着添加的纳米SiO2含量的增加,样品的溶剂抽出率降低。在浸泡24h后,添加5份纳米SiO2样品PVC的溶剂抽出率为18.9%,比对照(25.6%)降低了26.2%。添加少量的纳米SiO2并没有使样品的挥发损失率明显降低,添加1~5份不同量的纳米SiO2的样品的挥发损失率均比不添加纳米SiO2的对照样品低。随着无机纳米粒子含量的增加,样品的拉伸强度和断裂伸长率反而降低,硬度有所增加。      

稠油掺稀井系统效率评价方法研究及应用

针对稠油掺稀井系统效率低问题,通过分析2012年石油行业标准《SY/T5264-2012油田生产系统能耗测试和计算方法》,发现不适应稠油掺稀井系统效率评价因素主要有两方面,一是没有考虑油套环空与油管内流体密度差,二是没有考虑流体黏度摩阻损失,低估了有效举升扬程,造成稠油掺稀井系统效率评价偏低。在原有计算方法基础上引入密度差及黏度摩阻2个参数,制订了适合稠油掺稀井系统效率评价方法。通过将6口稠油掺稀井分别采用《SY/T5264-2012油田生产系统能耗测试和计算方法》和稠油掺稀井系统效率评价方法进行分析,发现后者较前者系统效率平均提升10.7%,提高了稠油掺稀井系统效率,指导油田节能降耗。     

介孔SiO2负载1,8-萘二酸酐结构表征及其荧光性能

分别利用单孔道MCM-41和双模型介孔分子筛(BMMs)作为载体通过氨丙基改性和负载荧光分子1, 8-萘二酸酐制备有机-无机杂化发光材料, 并采用XRD、TEM、SEM、BET、FT-IR、PL等手段对样品进行了结构表征.结果表明:具有双模型介孔结构的BMMs所制备的有机-无机杂化材料, 其发射峰位置(444 nm)较负载到单孔道的MCM-41中所制备的杂化材料的发射峰位置(450 nm)蓝移更明显, 主要原因是由于BMMs和MCM-41的颗粒形貌和大小不同所致.BMMs为球形颗粒(50 nm), 而MCM-41则为不规则颗粒且大小分布不均(1~3μm).     

Development of a Multi-Criteria Decision-Making Approach for Evaluating the Comprehensive Application of Herbaceous Peony at Low Latitudes

The growing region of herbaceous peony (Paeonia lactiflora) has been severely constrained due to the intensification of global warming and extreme weather events, especially at low latitudes. Assessing and selecting stress-tolerant and high-quality peony germplasm is essential for maintaining the normal growth and application of peonies under adverse conditions. This study proposed a modified multi-criteria decision-making (MCDM) model for assessing peonies adapted to low-latitude climates based on our previous study. This model is low-cost, timesaving and suitable for screening the adapted peony germplasm under hot and humid climates. The evaluation was conducted through the analytic hierarchy process (AHP), three major criteria, including adaptability-related, ornamental feature-related and growth habits-related criteria, and eighteen sub-criteria were proposed and constructed in this study. The model was validated on fifteen herbaceous peonies cultivars from different latitudes. The results showed that ‘Meiju’, ‘Hang Baishao’, ‘Hongpan Tuojin’ and ‘Bo Baishao’ were assessed as Level I, which have strong growth adaptability and high ornamental values, and were recommended for promotion and application at low latitudes. The reliability and stability of the MCDM model were further confirmed by measuring the chlorophyll fluorescence of the selected adaptive cultivars ‘Meiju’ and ‘Hang Baishao’ and one maladaptive cultivar ‘Zhuguang’. This study could provide a reference for the introduction, breeding and application of perennials under everchanging unfavorable climatic conditions.