Design and synthesis of small molecule-conjugated photoaffinity nanoprobes for a streamlined analysis of binding proteins

We designed and synthesized a set of photoaffinity nanoprobes, which multivalently display a small molecule ligand and a photoreactive group on gold nanoparticles. Due to the typically hydrophobic nature of these two functional groups, a hydrophilic spacer was additionally introduced to co-functionalize the nanoprobes to maintain their dispersibility in aqueous buffer solutions. Photoaffinity labeling studies using the nanoprobes composed of different ratios of three functional groups showed that including high density of the spacer group attenuates crosslinking efficiency. Comparative analysis of the reactivity among three major photoreactive groups suggested that unlike in the context of conventional photoaffinity probes, arylazide group enables the most selective crosslinking of a model small molecule binding protein.     

Influence of micronization (fine grinding) of soya bean meal and fullfat soya bean on productive performance and digestive traits in young pigs

Two trials were conducted to test the effect of micronization (very fine grinding) of soya bean meal (SBM) and fullfat soya bean (FFSB) on productive performance and digestive traits of piglets. The experimental design was completely randomized with four treatments arranged factorially (SBM and FFSB, micronized and ground). The mean particle size (MPS) was 47 and 881 μm for the SBM and 41 and 778 μm for the FFSB, micronized and ground, respectively. In trial 1 growth traits from 23 to 45 days of age and the coefficient of total tract apparent digestibility (CTTAD) of dietary components at 33 and 45 days of age were assessed. In trial 2 the coefficient of ileal apparent digestibility (CIAD) of dietary components, the pH of the gastro intestinal tract (GIT) and the weight of digestive organs and spleen were measured at 45 days of age. From 23 to 33 days of age pigs fed SBM grew faster (253 g/d versus 213 g/day; P<0.05) and were more efficient (0.87 g/g versus 0.98 g/g; P<0.01) than pigs fed FFSB. For the entire experiment (23–45 days of age) pigs fed SBM tended to grow more (360 g/day versus 324 g/day) and to eat more feed (414 g/day versus 380 g/day) than pigs fed FFSB (P<0.10). The CTTAD of crude protein (0.798 g/kg versus 0.778 g/kg), organic matter (0.864 g/kg versus 0.839 g/kg) and gross energy (0.849 g/kg versus 0.830 g/kg) were higher for pigs fed SBM than for pigs fed FFSB (P<0.001). In addition, CIAD of organic matter (0.765 g/kg versus 0.705 g/kg) and gross energy (0.761 g/kg versus 0.711 g/kg) were higher for SBM than for FFSB diets (P<0.001). The pH of the different segments of the GIT was not affected by the protein source (P>0.10). Particle size did not affect any trait studied (P>0.10). The poor performance and digestibility of pigs fed FFSB as compared to pigs fed SBM might be related to the conditions applied during processing. It is concluded that pigs fed soya bean meal perform better than pigs fed FFSB and that micronization of the soya protein sources does not affect any trait studied.     

Reproductive features of Celmisia species (Asteraceae) in relation to altitude and geographical range in New Zealand

A range of seed and flower characters was examined in 37 species of the New Zealand genus Celmisia (Asteraceae) to determine whether there were any relationships between reproductive features and the geographic or altitudinal ranges of the species. Using published sources and herbarium material, flower attractiveness to pollinators was measured in terms of capitulum size and ray/disc length ratio. Dispersibility was measured in terms of seed dry weight, seed terminal velocity, pappus/seed length ratio, and scape/leaf length ratio. Altitude (minimum and maximum) and geographic ranges (number of 1^o latitude x 1^o longitude squares occupied) were obtained from published sources. A multivariate principal components analysis using 12 morphological characters revealed the presence of five groups of species differing in capitulum size, seed weight, pappus length, number of pappus bristles, leaf length and scape length. Linear regressions showed that altitude was significantly and negatively related to seed dry weight and capitulum size, and positively to scape/leaf length ratio. Geographic range is negatively related to capitulum size, and positively to ray/disc ratio and altitudinal range. Amongst the seed features measured, seed weight was the best predictor of terminal velocity (an inverse measure of dispersability), but lighter seeds also had a higher pappus/seed length ratio. The frequency distribution of the geographic ranges of the species is highly skewed, with many local species (86% occurring in 15 or fewer one‐degree squares) and very few common ones. Two species (C. gracilenta and C. graminifolia) are notably more common than all the others. A comparison of these species with the others shows that, on average, they have lighter seeds with more bristles, taller scapes and higher ray/disc ratios, but have smaller capitula. The low geographic abundance of the rare species could not readily be attributed to any specific reproductive feature, possibly because of the multiple types of rarity represented within the genus.     

羟丙基淀粉的合成及其崩解性能的研究

以可溶性淀粉为原料,在一定条件下与不同量的环氧丙烷反应,得不同取代度的羟丙基淀粉,测其膨润度,对不同取代度的羟丙基淀粉的崩解性能作出初步评价。     

PP/PP-g-DBM/CaCO_3复合材料的力学性能研究

以聚丙烯接枝马来酸二丁酯(PP-g-DBM)作为聚丙烯(PP)/CaCO_3复合材料的界面改性剂,研制了PP/PP-g-DBM/CaCO_3复合材料,并且讨论了PP-g-DBM对聚丙烯/CaCO_3复合材料的力学性能的影响。结果表明:当CaCO_3含量为30%时,其抗冲性能达到6 kJ/m~2,相对于原料聚丙烯提高了20%;且较大程度地改善了分散相CaCO_3在连续相聚丙烯中的分散状态。     

偶联剂修饰纳米磁性微球的制备及其表征

以三氯化铁水溶液作原料,采用部分还原沉淀法,通过控制一些影响反应的参数,制备纳米磁性微球(Magnetic nanoparticles,MNPs),并用道康宁Z-6040硅烷偶联剂对其进行了表面修饰。利用透射电镜、X-射线衍射、红外光谱、古埃磁天平、可见光分光光度计等手段对MNPs的形貌、粒度分布、物相组成、表面包覆官能团、磁化率、分散性等进行了表征。用硅烷偶联修饰前后粒度分布呈高斯正态分布,主要集中在10～25mm;主要物相为Fe3O4晶体,另外还夹杂着少量γ-Fe2O3;分散性得到改善的同时,磁响应性保持良好。