减水剂类型对赤泥—矿渣基地聚物注浆材料性能的影响及机理研究

针对赤泥等固体废弃物对环境危害性大且利用率低等问题,以碱激发赤泥-矿渣基地聚物注浆材料为 研究对象,研究了不同掺量的聚羧酸(PA)减水剂、醛酮缩合物(AKC)减水剂和萘系(N)减水剂对材料凝结时间、流动 性及强度等的影响,并通过 XRD、傅里叶红外光谱及 SEM 等设备对减水剂的作用机理进行研究。 结果表明:减水剂增 强了材料的流动性但降低了材料的剪切应力;N 和 PA 减水剂能缩短材料的凝结时间,但 AKC 减水剂会延长材料的凝 结时间;N 和 AKC 减水剂能提高材料的强度,但 PA 减水剂会降低材料的强度;N 减水剂对材料的综合性能提升效果 更加明显,其最优掺量为 0. 7%;减水剂对赤泥-矿渣基地聚物性能提升的作用机理主要是促进地聚合物凝胶的形成。 研究成果为拓展赤泥在工程上的使用途径和效率提供了理论指导。     

Sugar-Pucker Force-Induced Transition in Single-Stranded DNA

The accurate knowledge of the elastic properties of single-stranded DNA (ssDNA) is key to characterize the thermodynamics of molecular reactions that are studied by force spectroscopy methods where DNA is mechanically unfolded. Examples range from DNA hybridization, DNA ligand binding, DNA unwinding by helicases, etc. To date, ssDNA elasticity has been studied with different methods in molecules of varying sequence and contour length. A dispersion of results has been reported and the value of the persistence length has been found to be larger for shorter ssDNA molecules. We carried out pulling experiments with optical tweezers to characterize the elastic response of ssDNA over three orders of magnitude in length (60–14 k bases). By fitting the force-extension curves (FECs) to the Worm-Like Chain model we confirmed the above trend:the persistence length nearly doubles for the shortest molecule (60 b) with respect to the longest one (14 kb). We demonstrate that the observed trend is due to the different force regimes fitted for long and short molecules, which translates into two distinct elastic regimes at low and high forces. We interpret this behavior in terms of a force-induced sugar pucker conformational transition (C3′-endo to C2′-endo) upon pulling ssDNA.     

超声强化过氧化氢-维生素C体系糖汁脱色的研究

研究超声强化过氧化氢-维生素C复合脱色剂体系对糖汁脱色的规律,考察了超声功率、复合脱色剂用量、超声温度和时间对糖汁脱色率的影响。试验结果表明:超声空化强化过氧化氢-维生素C对糖汁具有良好的脱色效果,当处理糖汁量为100 mL,超声功率为260 W,过氧化氢与维生素C的用量均为1.6 mL,空化温度为70℃,超声时间为6 min时,脱色率达到53.4%。通过正交试验分析,得到各个因素对糖汁脱色率影响的主次关系为:超声功率>复合脱色剂用量>超声时间>空化温度。     

Breaking a Couple: Disulfide Reducing Agents

Cysteine is present in a large number of natural and synthetic (bio)molecules. Although the thiol side chain of Cys can be in a free form, in most cases it forms a disulfide bond either with a second Cys (bridge) or with another thiol, as in the case of protecting groups. Efficient reduction of these disulfide bridges is a requirement for many applications of Cys-containing molecules in the fields of chemistry and biochemistry. Here we review reducing methods for disulfide bonds, taking into consideration the solubility of the substrates when selecting the appropriate reducing reagent.     

生姜红糖风味发酵乳的制备

以生牛乳、白砂糖、红糖、生姜汁为主要原料，保加利亚乳杆菌（Lactobacillus bulgaricus）为发酵剂，研制生姜红糖风味发酵乳。以酸度和感官评分为评价指标，通过单因素试验、正交试验优化生姜红糖风味发酵乳的工艺条件。结果表明，生姜红糖风味发酵乳的最佳工艺条件为白砂糖5.0%、红糖3.5%、生姜汁2.5%、发酵时间5.0 h。在此优化条件下，生姜红糖风味发酵乳呈红褐色，红糖风味浓郁，生姜味明显且辣感舒适，酸甜适中，组织细腻均匀，感官评分为93分，酸度为74.8 °T，蛋白质含量为2.89%，脂肪含量为3.17%，乳酸菌总数为5.1×108 CFU/g，致病菌未检出。产品质量指标满足国标GB 19302—2010《食品安全国家标准 发酵乳》要求。     

基于趋势分析的舰载机预防性维修工作优化技术研究

针对缩减舰上保障规模和提高舰载机的完好率的需求，提出舰载机预防性维修工作优化方法。分析了如何选取优化项目和参数，对比分析了各种趋势分析方法的适用性，采用基于飞参数据的趋势分析方法，刻画系统或部件的性能变化趋势，提供适合单机的舰载机预防性维修工作优化决策支撑，并以典型系统进行了案例应用，形成了一种新的舰载机提高保障效能、提升系统安全性水平的技术途径。     

Organic Additives for the Enhancement of Laminar Flow in a Brain‐Vessels‐Like Microchannel Assembly

Organic polymers were extracted from okra, aloe vera, and hibiscus leaves and used as drag‐reducing additives (DRAs) to enhance the laminar flow in custom‐made microchannels that simulate the human brain vessels. The experiment was conducted using an open‐loop microfluidic system. The flow enhancement performance was evaluated as the function of percentage of flow increment of mucilage additives at different concentrations. Okra mucilage showed greater flow enhancement performance at higher mucilage concentration while both aloe vera and hibiscus mucilage performed better at lower additive concentration. The findings prove the potential of these organic polymers as DRAs to enhance the blood flow.     

Plastic-containing materials as alternative reductants for base metal production

Shredder residue materials are produced after the removal of ferrous and non-ferrous fractions from end-of-life electronic equipment. Despite the high plastic content and metal value in the ash, high percentages of these materials are currently sent to landfills. In this study, the potential of utilising shredder residue material and other plastic-containing materials as reducing agents was studied. Plastic-containing materials were co-injected with coal into a zinc-fuming furnace in Boliden-Rönnskär smelter. The data obtained from the trial, such as the data from the chemical analysis of the slag and the steam production, are discussed. The observations indicate that plastic-containing material can replace up to 1?ton?h^?1 of coal without a significant decrease in the zinc reduction rate.     

Using spray-dried sugar beet molasses in ice cream as a novel bulking agent

In this study, it is aimed to investigate and evaluate the use of molasses which is a by-product of sugar production as a novel bulking agent in ice cream as a sugar replacer. Sugar beet molasses (75%) and 12 DE maltodextrin (25%) were converted into powder form by spray drying. Spray-dried sugar beet molasses (SDSM) was then used as a substitute of sugar in different ratios (0:100, 25:75, 50:50, 75:25 and 100:0) in the ice cream products. The increased amount of SDSM decreased the overrun, L*, whiteness index (WI) and melting behaviours and increased a*, b*, total phenolic content, consistency and viscosity. Meanwhile, thermal properties have not been affected by the use of SDSM (P < 0.05). The sensory findings have been particularly interesting especially when replacing above 50% sugar with SDSM, aroma, flavour and general acceptability decrease. According to the results of this study, substituting 25% of total sugar with SDSM as a bulking agent can decrease cost of the product and improve total phenolic content and some quality parameters without compromising sensorial properties.