Molecular Dynamics Study of Interaction between Acrylamide Copolymers and Alumina Crystal

Four acrylamide polymer flocculants, anionic polyacrylamide P(AA-co-AM), cationic poly-acrylamide P(DMB-co-AM), nonionic polyacrylamide P(AM), and hydrophobical polyacry-lamide P(OA-co-AM) have been prepared by copolymerizing with acrylic acid, cationic monomer dimethylethyl (acryloxyethyl) ammonium bromide (DMB) and hydrophobical monomer octadecyl acrylate with acrylamide. The interactions between the flocculants withthe (012) surface of alumina crystal (Al₂O₃) have been simulated by molecular dynamics method. All the polymers can bind tightly with Al₂O₃ crystal, the interaction between the O of polymers and Al of the (012) surface of Al₂O₃ is significantly strong. The order of binding energy is as follows: P(DMB-co-AM)>P(OA-co-AM)>P(AA-co-AM)>P(AM), implying a better flocculation performance of P(DMB-co-AM) than the others. Analy-sis indicates that binding energy is mainly determined by Coulomb interaction. Bonds are found between the O atoms of the polymers and the Al atoms of Al₂O₃. The poly-mers' structures deform when they combine with Al₂O₃ crystal, but the deformation en-ergies are low and far less than non-bonding energies. Flocculation experiments in sus-pension medium of 1%Kaolin show a transmittancy of 90.8% for 6 mg/L P(DMB-co-AM) and 73.0% for P(AM). The sequence of flocculation performance of four polymers is P(DMB-co-AM)>P(OA-co-AM)>P(AA-co-AM)>P(AM), which is in excellent agreement with the simulation results of binding energy.     

Molecular Dynamics Simulation on Scale Inhibition Mechanism of Polyepoxysuccinic Acid to Calcium Sulphate

Molecular dynamics simulation has been performed to simulate the interaction between PESA and the (001) face of anhydrite crystal CaSO₄ at different temperatures with the presence of various number of H₂O molecules. The results show that PESA can effectively prevent the growth of CaSO₄ scale at 323-343 K. At the same temperature, the binding energy between PESA and the (001) face of CaSO₄ for systems with various number of H₂O has the order of E_bind(0H₂O)>E_bind(200-400H₂O)>E_bind(100H₂O). For the same system at different temperatures the binding energies are close and are mainly contributed from the Coulomb interaction, including ionic bonds. The bonds are formed between the calcium atoms of anhydrite scale crystal and the oxygen atoms of the carboxyl group of PESA. Hydrogen bonds are formed between the O atoms of the carboxyl group of PESA and the H atoms of H2O. van der Waals interaction is conducive to the stability of the system of PESA, H₂O, and CaSO₄. The radial distribution functions of O(carbonyl of PESA)-H(H₂O),O(CaSO₄)-H(H₂O), and O(CaSO₄)-H(PESA) imply that solvents have effects on the anti-scale performance of PESA to CaSO₄.     

海洋减阻技术的研究现状

船舶、舰艇、鱼雷等海中航行体在海洋经济建设和海洋国防中发挥着重要作用.海中航行体的运行速度和能量消耗率是评价其性能的重要指标.利用减阻技术降低航行体在海水中的行驶阻力具有重要意义.按减阻机理对现今重要的海洋减阻技术进行分类和总结,并详细介绍其研究现状和减阻机理,主要包括仿生减阻、微气泡减阻和疏水/超疏水涂层减阻.通过对现有海洋减阻技术的总结和分析,展望了其今后的研究重点.     

基于高光谱图像和偏最小二乘的羊肉pH值特征波段筛选研究

波段筛选方法的选取以及随后的光谱特征波段的提取对高光谱模型效果的影响较大。为了快速准确检测羊肉的pH值,开展并讨论了利用两种特征波段筛选方法对羊肉pH值高光谱模型的影响研究。本研究采用二阶导数(2D)、多元散射校正(MSC)和中心化处理(mean-centering)相结合的方法对所提取纯肌肉部分的代表性光谱进行预处理,利用联合区间偏最小二乘(siPLS)和联合区间偏最小二乘结合遗传算法(siPLS-GA)对全波段473～1000 nm范围光谱进行特征波段的提取,并分别建立相对应特征波段范围羊肉pH的PLS预测模型,同时与全波段的PLS模型效果相比较。结果表明采用siPLS-GA提取的特征波长建立的PLS模型效果最优,其选取的特征波长点数为56,校正集相关系数(R_cal)和均方根误差(RMSEC)分别为0.96和0.043,预测集相关系数(R_P)和均方根误差(RMSEP)分别为0.96和0.048。siPLS-GA方法既能够减少建模使用的光谱变量,又可以提高模型精度,因此利用高光谱图像技术结合siPLS-GA可以实现羊肉pH的特征波段筛选和快速准确检测。     

抗氧剂对低芥酸菜籽油摩擦学性能的影响

考察了酚型、胺型以及二烷基二硫代氨基甲酸酯３种抗氧剂对低芥酸菜籽油摩擦学性能的影响,并通过对摩擦过程中基础油碘值和酸值变化的测定以及钢球磨损表面的反射红外光谱分析,探讨了菜籽油作为润滑剂基础油的摩擦化学作用机理。结果表明：抗氧剂使基础油的摩擦学性能变差,表现出明显的对抗效应。     

2000m~3在役压力容器应力状况分析

本文报道了钢制 2 0 0 0 m3球罐实际运行一年后的应力状况 ,对球罐的残余应力及工作应力进行了现场测试 ,发现球罐虽经过整体热处理 ,但局部残余应力仍较高等问题 ,并进行了对比分析 .     

具有二氧化碳响应性的纳米球形聚电解质刷的制备及其乳化性能

以聚苯乙烯(PS)纳米球为核,利用紫外光引发聚甲基丙烯酸N,N-二甲基氨基乙酯(PDMAEMA)接枝到PS纳米球上,得到对CO_2有刺激响应的聚甲基丙烯酸N,N-二甲基氨基乙酯刷(PS-PDMAEMA)。动态光散射(DLS)、电导率结果表明PS-PDMAMEA具有CO_2刺激响应性。该微粒可以作为Pickering乳液的乳化剂,通过导入CO_2或N_2作为开关,进而破坏或稳定Pickering乳液。用数码照片、偏光显微镜等方法表征了乳液的稳定情况。结果表明:PS-PDMAEMA具有很好的CO_2刺激响应性,利用PS-PDMAEMA作为乳化剂稳定Pickering乳液,仅仅依靠气体开关(CO_2或N_2)就可改变乳液的稳定性。     

超高效液相色谱-串联质谱法同时测定祛痘类化妆品中保泰松与氨基比林的研究

建立了快速测定祛痘类化妆品中保泰松和氨基比林的固相萃取/超高效液相色谱-串联质谱分析方法。样品以乙腈为提取溶剂超声萃取,经Oasis HLB固相萃取柱净化浓缩后,采用Eclipse XDB-C_(18)(3.5μm,4.6 mm×150 mm)色谱柱进行分离,甲醇-10 mmol·L~(-1)乙酸铵溶液为流动相梯度洗脱,流速为0.5mL·min~(-1)。采用电喷雾正离子源(ESI+),多反应监测(MRM)扫描方式检测,基质匹配标准曲线法定量。结果表明,保泰松和氨基比林在2.0~200.0μg·L~(-1)范围内线性关系良好,相关系数(r2)均大于0.99,方法检出限分别为1.5、0.8μg·kg~(-1),定量下限分别为4.9、2.7μg·kg~(-1)。低、中、高3个加标水平下的平均回收率为77.8%~93.4%,日内相对标准偏差(RSD)为2.4%~7.8%,日间RSD为3.6%~9.5%。该方法简捷、快速、检出限低,能够为化妆品中保泰松和氨基比林残留状况的监测工作和产品质量控制提供科学依据和技术支持。     

The effect of nitro groups on the structures and energetic properties of the derivatives composed of TATB and cubane

Based on the successful experience of synthesis of the TATB (1, 3, 5-triamino-2, 4, 6-trinitrobenzene) and cubane, we propose to consider their nitro derivatives combined by C–N bond as a series of high energy density compounds. First principles molecular orbital calculations have been used to investigate the structural and energetic properties, including the heat of formation, density, detonation performance, and impact sensitivity. Natural bond orbital analysis was carried out to investigate the influence of substituents on the electron delocalization. The results implied that the inclusion of nitro group will decrease the stability of cage skeleton and weaken the C–NO₂ bond. The calculated heats of formation, density, detonation velocity, and detonation pressure are positive and large. The results revealed that two of five derivatives have the close performance and sensitivity to those of CL-20, indicating that they may be explored as new potential high energy materials. Leave them with the notable value to dig out.     

压力容器高应变区应变疲劳裂纹扩展试验研究

针对压力容器几何结构不连续高应变区断裂和疲劳破坏特点,本文通过对应变循环条件下疲劳裂纹扩展影响因素和控制参量的理论分析,提出将△J作为应变循环条件下疲劳裂纹扩展速率的控制参量,并在EPRI弹塑性断裂分析工程方法基础上,提出了△J的工程计算方法,并通过模拟应变疲劳裂纹扩展的SCT试样试验,验证了△J工程计算方法的可靠性,根据SCT试样应变疲劳裂纹扩展试验研究结果,在考虑了压力容器高应变区几何形状和材质变化对应变疲劳裂纹扩展参量影响后,提出了一种压力容器高应变区应变疲劳裂纹扩展速率工程估算方法。