双水相气浮溶剂浮选法分离富集杜仲叶中京尼平苷酸

目的采用乙醇/Na H2PO4双水相气浮溶剂浮选技术,结合响应曲面法对杜仲叶中京尼平苷酸进行分离富集研究。方法考察了无机盐种类和用量、有机溶剂的种类和用量、粗提液加入量、空气体积流量和浮选时间对京尼平苷酸浮选效果的影响,在单因素试验基础上,选择Na H2PO4质量分数、乙醇体积分数和空气体积流量为实验因素,采用Box-Behnken中心组合设计进行优化实验,确定京尼平苷酸的最优浮选工艺,并进行100倍放大研究。结果在28%Na H2PO4、23%乙醇双水相体系中,加入5 g粗提液,当空气体积流量为40 m L/min,浮选时间为20 min时,京尼平苷酸浮选效率最佳,达到97.88%,富集倍数达到27.34。100倍放大后,京尼平苷酸的浮选效率达到95.60%,RSD为0.77%。结论乙醇/Na H2PO4双水相气浮溶剂浮选体系对京尼平苷酸的浮选效率高,富集倍数大,为杜仲叶中环烯醚萜类活性成分分离富集提供了一种有效的新方法。     

Bias-reduced and separation-proof GEE with small or sparse longitudinal binary data

Generalized estimating equation (GEE) is a popular approach for analyzing correlated binary data. However, the problems of separation in GEE are still unknown. The separation created by a covariate often occurs in small correlated binary data and even in large data with rare outcome and/or high intra-cluster correlation and a number of influential covariates. This paper investigated the consequences of separation in GEE and addressed them by introducing a penalized GEE, termed as PGEE. The PGEE is obtained by adding Firth-type penalty term, which was originally proposed for generalized linear model score equation, to standard GEE and shown to achieve convergence and provide finite estimate of the regression coefficient in the presence of separation, which are not often possible in GEE. Further, a small-sample bias correction to the sandwich covariance estimator of the PGEE estimator is suggested. Simulations also showed that the GEE failed to achieve convergence and/or provided infinitely large estimate of the regression coefficient in the presence of complete or quasi-complete separation, whereas the PGEE showed significant improvement by achieving convergence and providing finite estimate. Even in the presence of near-to-separation, the PGEE also showed superior properties over the GEE. Furthermore, the bias-corrected sandwich estimator for the PGEE estimator showed substantial improvement over the standard sandwich estimator by reducing bias in estimating type I error rate. An illustration using real data also supported the findings of simulation. The PGEE with bias-corrected sandwich covariance estimator is recommended to use for small-to-moderate size sample (N ≤ 50) and even can be used for large sample if there is any evidence of separation or near-to-separation.     

The graphical representation of the self-image in early development: twins and singletons in comparison

The construction of self, a fundamental process for development. Twins, as they grow together, may encounter greater difficulties in individuation process. The present study aims to investigate the construction of the image of the self and of the self with its own twin/sibling through the drawing of the human figure and to highlight any differences in these representations between monozygotic twins, dizygotic twins, and non-twins. A sample of 105 children aged between 4 and 6 years participated in the research. From the analysis of the drawings of the self and of the self with the sibling, differences in self-representation and representation with the sibling have emerged and can be understood in the light of the separation and individuation process that characterizes the development of the self-image. In particular, greater tendencies have emerged for monozygotic twins to represent themselves differently from the co-twin and for dizygotic twins to show identical figures.     

Psychological distress following marital separation interacts with a polymorphism in the serotonin transporter gene to predict cardiac vagal control in the laboratory

Marital separation is linked to negative mental and physical health; however, the strength of this link may vary across people. This study examined changes in respiratory sinus arrhythmia (RSA), used to assess cardiac vagal control, in recently separated adults (N = 79; M time since separation = 3.5 months). When reflecting on the separation, self‐reported psychological distress following the separation interacted with a polymorphism in the serotonin transporter gene (5‐HTTLPR) and a relevant single nucleotide polymorphism (SNP), rs25531, to predict RSA. Among people reporting emotional difficulties after the separation, those who were homozygous for the short allele had lower RSA levels while reflecting on their relationship than other genotypes. The findings, although limited by the relatively small sample size, are discussed in terms of how higher‐sensitivity genotypes may interact with psychological responses to stress to alter physiology.     

Toughening Polylactide with Phase‐Separating Complex Copolymer Architectures

Polylactide (PLA) is a commercially produced potentially sustainable plastic that holds promise to replace petroleum‐sourced materials. Unfortunately, the brittle nature of PLA limits its current utility to disposable packaging. Melt blends of PLA and a rubbery material can rubber toughen the plastic, but often require the addition of a compatibilizer and generate opaque materials. Current efforts explore using block and graft copolymers with a majority PLA block and minority rubbery block that phase separate on the nanometer length scale to rubber toughen PLA. With these complex architectures, the polymer matrix, the minor rubbery component, and the compatibilizer are present in one molecule. Many block and graft copolymers rely on non‐sustainable rubbery blocks, which limits the sustainability of these materials. Recent work has utilized polyisoprene (PI) as the sustainable backbone for PLA graft copolymers. Post‐polymerization functionalization and copolymerization of PI provides a method to create fully sustainable PLA/PI graft copolymers that phase separate on the nanometer‐scale to make potentially tough, sustainable plastics.

     

Characterization of Phase Structures of Novel Metallo‐Polyurethanes

Two series of chemically well‐defined polyurethanes (PUs) have been synthesized containing two different soft segments of interest in aerospace applications. At a given soft fragment, four different hard segments (HSs) based on single diisocyanate molecules with no chain extenders have been incorporated. Both segmented PU series have been prepared by stoichiometric reactions of the macrodiol hydroxyl‐terminated polybutadiene (HTPB), and a metallo‐derived, this being the (ferrocenylbutyl) dimethylsilane grafted on HTPB, so‐called Butacene. Those HSs are isophorone diisocyanate, toluene‐2,4‐diisocyanate, 4,4′‐diphenyl methane diisocyanate, and hexamethylene diisocyanate. Microphase separation and morphology development have been studied at room temperature in these copolymers using Fourier transform infrared spectroscopy, analyzing the change in the relative intensities of free and hydrogen‐bonded carbonyl peaks. Measurements of wide‐ and small‐angle X‐ray diffraction using synchrotron radiation allow analyzing the morphological and microstructural differences between these two series of samples. In addition, dynamic mechanical analysis and differential scanning calorimetry have been used to learn about the relaxation processes and thermal transitions that are observed in these materials and to confirm the existence or lack of phase segregation. The knowledge of structure–property relationship is very important in these advanced organometallic PUs to get an understanding of their application as solid composite propellants binder.

     

Synthesis and Properties of Segmented Polyurethanes with Triptycene Units in the Soft Segment

Segmented polyurethanes based on poly(tetramethylene glycol) soft segments (SS) containing aromatic units are synthesized. Hydroquinone bis(2‐hydroxyethyl) ether and 4,4′‐methylenebis(phenyl isocyanate) are used as the chain extender and the diisocyanate, respectively. Effects of incorporation of hydroquinone (HQ) and triptycene hydroquinone into the soft segments on the morphology and properties of the undeformed segmented polyurethanes are investigated. Differential scanning calorimetry and dynamic mechanical analysis indicate that the incorporation of triptycene units leads to an increased glass transition temperature (T_g) and an elimination of the crystallization of soft segments. The tensile analysis shows there is no strain hardening for the polymer films with triptycene‐containing soft segments. Wide‐angle x‐ray diffraction demonstrates that the absence of strain hardening in triptycene‐containing segmented polyurethane likely arises from the suppressed strain induced crystallization. In contrast, the less bulky HQ units show little effect on either thermally or strain induced crystallization of the soft segments. Morphology studies, including small angle x‐ray scattering on the compression molded films and atomic force microscopy on the solvent cast film, reveal that polyurethanes with HQ and triptycene containing soft segments maintain distinct microphase separated morphology.

     

大孔吸附树脂分离纯化地骨皮总黄酮实验研究

目的：研究并优化大孔吸附树脂分离纯化地骨皮总黄酮的方法。方法：先以总黄酮含量为考察指标,从3种不同型号的树脂中筛选出分离纯化地骨皮总黄酮的最佳树脂,再对最佳树脂吸附工艺参数进行全面优化。结果：AB-8型大孔吸附树脂对地骨皮总黄酮的吸附与解析性能最好,确定最佳洗脱条件为体积分数50%乙醇洗脱,溶剂用量2 BV（树脂床体积）。结论：AB-8型大孔吸附树脂可有效地分离纯化地骨皮总黄酮。     

A new cultivation system for studying chemical effects on the lifespan of the fruit fly

A side-by-side comparison was made between a conventional vial system and a novel bottle system for cultivating flies and testing the effect of chemical exposure on the lifespan of the flies. While the two cultivation systems yielded very similar results for the effect of DEHP (di[2-ethylhexyl] phthalate) on reducing the lifespan of fruit fly Drosophila melanogaster, the new bottle system has many advantages over the conventional vial system. The bottle system allowed long-term cultivation of flies in the same bottle and thus eliminated the need for transferring of flies between vials. Foods/nutrients were provided as fresh moisture medium coated on a glass slide vertically hanged in the center of the bottle. Fly discharges and dead flies were collected onto a draw horizontally inserted into the bottom of the bottle. These features have resulted in great convenience for cultivating flies and reduced labor and media cost. The effective separation of food from discharge may allow accurate mass balance measurement and thus yield more definitive observations for understanding the actual role of calorie restriction (CR) or dietary-restriction (DR) in fly metabolism and longevity.