Liquid-Liquid Extraction of Acids and Water by a Malonamide: I-Anion Specific Effects on the Polar Core Microstructure of the Aggregated Malonamide

In a solvent extraction process, the compositions of the phases in thermodynamic equilibrium (described as a Winsor-II regime) must be determined to obtain the extraction isotherms of ions as well as co-extracted water. By comparing the extractions of a series of acids by the malonamide DMDOHEMA (N,N’-dimethyl-N,N’-dioctyl hexylethoxy malonamide) in n-heptane, the specific anion effects regarding third phase formation and the strength of the acid-extractant interaction were investigated. It is shown that third phase formation is driven by hydration enthalpy of acid, while the polar core microstructure is controlled by the pKa of the acids. Upon acid extraction, the promotion of third phase formation follows the series H₂SO₄ ≈ H₃PO₄ ≈ HClO₄ > HNO₃ > HCl > HCOOH, which correlates to hydration enthalpy of acid in the case of monoacids. The combination of IR spectroscopy and DFT calculations revealed two different modes of acid extraction, either by hydrogen bonding (extraction of non-dissociated acid: HA) or by protonation of the extractant (extraction of dissociated acid: H⁺A^?). The strength of the amide-acid interaction (protonation vs. hydrogen bonding) is correlated to the pKa of the acid and is responsible for the microstructure of the solution.     

河南低品位铝土矿工艺矿物学研究

研究的河南低品位铝土矿的铝硅比为3.81,Al2O3含量为59.67%,铝的赋存状态复杂,铝矿物主要为微晶—隐晶产出的一水硬铝石,与铝硅酸盐矿物之间的嵌布关系复杂,在粗磨条件下矿物难以解离。但此类矿石中具有一定产出形状的一水硬铝石集合体的铝硅比相对较高,一般大于7,为富集合体,符合选冶物料品质要求,能成为选矿回收的对象。据此来确定此类矿石中一水硬铝石的磨矿细度,为放粗矿石的磨矿细度提供基础数据,也为氧化铝的高效低耗富集提供科学依据。     

Effects of heat-treated β-lactoglobulin and its aggregates on foaming properties

The effects on foaming properties of the aggregates formed by heating concentrate beta-lactoglobulin solutions (55 mg mL⁻¹, pH 6.8) at 85 °C from 1 to 15 min were investigated. Structural characteristics (size and molecular conformation), hydrophobicity and protein aggregates proportion were also studied. All tested methods pointed at 3 min of heating as a critical time, in terms of conformational changes and aggregation processes. At this time, the most significant conformational changes took place: non-native monomers were present and the greatest amount of dimers and trimers was produced, which was proved with the results of gel densitometry of SDS-PAGE, fluorescence quenching and circular dichroism tests. Foamability and foam stability were both improved by pre-heating the protein. A constant proportion among beta-lactoglobulin species (monomer 51%, dimer 33% and trimer 16%), regardless the protein concentration, led to the same results on foaming properties, confirming the link with structural changes. Aggregates formed by heating beta-lactoglobulin up to 10 min produced more stabilized foams, slowing down disproportionation, because of the formation of stiffer films. The increase in surface hydrophobicity was considered a decisive factor in the improved foamability and hydrophobic interactions improved the foam stability trough the rapid formation of a viscoelastic film.     

高性能钢纤维增强混凝土的抗侵彻行为及数值模拟(英文)

采用大掺量超细工业废渣取代水泥,并掺加了天然河砂以及高弹、高强的玄武岩石子,制备了不同强度等级的高性能钢纤维增强混凝土材料。采用φ25mm弹道炮开展了初速度为500～850m/s的正侵彻实验,获得了弹丸着靶速度、最大侵彻深度、弹坑直径以及靶体破坏形态等实验参数,采用经典公式对侵彻深度进行了分析,同时采用非线性有限元方法对侵彻全过程进行了数值模拟。结果表明:侵彻深度随着材料强度等级的提高略有降低,粗集料的掺加有利于提高靶体的抗侵彻能力,随着纤维掺量的降低以及侵彻速度的提高,材料破坏程度明显加剧,数值模拟结果同试验结果吻合较好,侵彻深度的模拟结果与试验值的误差均在5%以内。     

The Capillarity of Mica-Rich Base-Course Aggregates

In regions of temperate climate, the destructive influence of frost is the main contributor to damage of a road structure. Commonly, the frost susceptibility of base-course aggregates is often ignored in road construction. However, a number of studies on aggregates for construction purposes, and field observations of road failures, indicate a negative influence of mica-rich rock aggregates (used in unbound applications) on the service life of road construction. The scope of the current work investigates the capillary properties of unbound base-course aggregates with varying free mica grains. The materials studied in this research are commercially available road construction aggregates, and originate from different regions of Sweden. The mineral composition of the samples has been determined by polarizing microscopy using a point-count method. The parameter characterizing the capillarity was measured using the test for determining capillary rise (VVMB24). The results show that there is a direct correlation between mica content of the aggregates and water suction by capillary forces. Therefore, mica-rich materials susceptible to frost heave, thus confirming the tendency for frost damage of unbound aggregates.     

The effects of hydrogen addition on silica aggregate growth in atmospheric-pressure, 1-D methane/air flames with hexamethyldisiloxane admixture

The effect of hydrogen addition on silica growth in burner-stabilized methane/air flames with trace amounts of hexamethyldisiloxane are reported. Profiles of the aggregates' radius of gyration $R_g$ and monomer radius $a$ versus residence time were measured by laser light scattering. Experiments were performed at equivalence ratios of 0.8, 1.0 and 1.3, with mole fractions of 0–0.4 of hydrogen in the fuel. At equal mass flux, the addition of hydrogen was found to result in decreasing $R_g$ and $a$. However, keeping the flame temperature rather than the mass flux constant upon hydrogen addition resulted in the same measured profiles.     

水泥基复合材料邻近集料表面最近间距分布的解析解

依据Torquato的最邻近表面函数公式,推导出了水泥基复合材料邻近集料表面最近间距分布的解析解。采用计算机模拟方法生成了一个模型,选取邻近集料表面最近间距概率密度分布曲线和累计概率分布曲线两个参数,对比模拟结果与理论结果之间的差别。通过比较发现,该理论解析解与模拟试验结果能够很好地吻合。利用该解析解,研究了在常用集料体积分数下,符合Fuller分布的砂浆和混凝土中邻近集料表面最近间距分布及邻近集料表面最近间距平均值随集料体积分数和集料细度的变化关系。     

Punching shear behavior of recycled aggregate concrete slabs with and without steel fibres

A study on the punching shear behavior of 8 slabs with recycled aggregate concrete (RAC) was carried out. The two main factors considered were the recycled coarse aggregate (RCA) replacement percentage and the steel fibre volumetric ratio. The failure pattern, load-displacement curves, energy consumption, and the punching shear capacity of the slabs were intensively investigated. It was concluded that the punching shear capacity, ductility and energy consumption decreased with the increase of RCA replacement percentage. Research findings indicated that the incorporation of steel fibres could not only improve the energy dissipation capacity and the punching shear capacity of the slab, but also effectively improve the integrity of the slab tension surface and thereby changing the trend from typical punching failure pattern to bending-punching failure pattern. On the basis of the test, the punching shear capacity formula of RAC slabs with and without steel fibres was proposed and discussed.     

粗粒含量对排土场堆石体剪切变形和强度的影响研究

为探讨粗粒含量对堆石体剪切特性的影响, 采用室内中型直剪仪, 对不同组构试样开展了剪切试验。研究表明, 粗粒料剪切过程中没有明显的峰值强度, 且应力应变关系表征为应变硬化型。相同正应力条件下, 试样剪切应变达到1/100时的剪切模量随粗粒含量增加而增大, 试样在破坏时的剪切模量随着粗粒含量增加呈先增大后减小的趋势, 且粗粒含量为70%时试样剪切破坏模量达到最大值。粗粒料内摩擦角与粗粒含量之间存在指数关系, 相关系数为0.912 6, 摩擦角随粗粒含量增加而增大; 粘聚力与粗粒含量间的规律性尚不明显。