Phase behavior of carbon dioxide-aromatic hydrocarbon mixtures

Occhiogrosso, R.N., Igel, J.T. and McHugh, M.A., 1986. Phase behavior of carbon dioxide-aromatic hydrocarbon mixtures. Fluid Phase Equilibria, 26: 165–179.Vapor-liquid-equilibria experiments are conducted at 299.25, 305.65, 316.25, 338.35, 363.15, and 383.15 K and for pressures up to 175 bar for the CO₂-isopropyl benzene (cumene) system. Pressure-composition information is obtained. The resulting experimental data are modeled using the Peng-Robinson equation-of-state. Two temperature-independent model parameters, δ_ij, which accounts for molecular interactions between CO₂ and cumene, and η_ij, which accounts for the size difference between CO₂ and cumene, are used to obtain good agreement between calculated and experimental data.The results for the CO₂-cumene system are compared to the CO₂-toluene and CO₂-m-xylene systems which are available in the literature. The CO₂-toluene and CO₂-m-xylene systems can be modeled using the same δ_ij and η_ij values used for the CO₂-cumene system.     

1,3-丙二胺的不对称双Schiff碱异三核配合物的合成表征、晶体结构与磁性研究

合成了一种新的不对称双Schiff碱Cu(II)单核配合物Cu(HLt) (1) (H₃Lt为N-3-羧基水杨醛-N'-水杨醛-缩1,3-丙二胺)及其两个异三核配合物[(CuLt)₂Ni]•2.5H₂O (2)和[(CuLt)₂Mn]•5H₂O (3), 并用元素分析、红外光谱、电子光谱对它们进行了结构表征. 用X射线单晶衍射法测定了配合物3的晶体结构, 其晶胞中每个不对称单元包含一个异三核中性分子, 在此三核分子中, 中心Mn^2＋离子位于[O₆]的变形八面体配位环境中, 两个端基Cu^2＋离子位于[N₂O₂]的平面正方场中. 在5～300 K范围内测定了两个三核配合物的变温磁化率, 经拟合得化合物2的磁交换参数为－57.7 cm^－1, 化合物3的磁交换参数为－28.5 cm^－1, 表明在两个异三核配合物中, 中心M^2＋离子与外部Cu^2＋离子间存在弱的反铁磁自旋交换作用.     

二维材料改性水性聚氨酯防腐涂料的研究进展

水性聚氨酯涂料作为一种新兴的环保涂料,在防腐领域得到了广泛应用。然而,水性聚氨酯涂料交联密度低,耐水性稍差,不利于其长效防腐性能。利用具有独特物理化学特性的二维材料作为水性聚氨酯的填料,可以有效改善其性能。本文主要介绍了三种二维材料(石墨烯、MXene和六方氮化硼)作为填料与水性聚氨酯进行复合,并重点介绍了石墨烯、MXene和六方氮化硼的改性方法,并对水性聚氨酯复合涂层的性能进行了阐述和比较,最后对未来二维材料/水性聚氨酯的复合材料的发展和应用进行了展望。     

Adversarial Data Hiding in Digital Images

In recent studies of generative adversarial networks (GAN), researchers have attempted to combine adversarial perturbation with data hiding in order to protect the privacy and authenticity of the host image simultaneously. However, most of the studied approaches can only achieve adversarial perturbation through a visible watermark; the quality of the host image is low, and the concealment of data hiding cannot be achieved. In this work, we propose a true data hiding method with adversarial effect for generating high-quality covers. Based on GAN, the data hiding area is selected precisely by limiting the modification strength in order to preserve the fidelity of the image. We devise a genetic algorithm that can explore decision boundaries in an artificially constrained search space to improve the attack effect as well as construct aggressive covert adversarial samples by detecting “sensitive pixels” in ordinary samples to place discontinuous perturbations. The results reveal that the stego-image has good visual quality and attack effect. To the best of our knowledge, this is the first attempt to use covert data hiding to generate adversarial samples based on GAN.     

Tolman length of simple droplet: Theoretical study and molecular dynamics simulation

In 1949, Tolman found the relation between the surface tension and Tolman length, which determines the dimensional effect of the surface tension. Tolman length is the difference between the equimolar surface and the surface of tension. In recent years, the magnitude, expression, and sign of the Tolman length remain an open question. An incompressible and homogeneous liquid droplet model is proposed and the approximate expression and sign for Tolman length are derived in this paper. We obtain the relation between Tolman length and the radius of the surface of tension(R_s) and found that they increase with the Rs decreasing. The Tolman length of plane surface tends to zero. Taking argon for example, molecular dynamics simulation is carried out by using the Lennard–Jones(LJ) potential between atoms at a temperature of 90 K. Five simulated systems are used, with numbers of argon atoms being 10140, 10935, 11760, 13500, and 15360, respectively. By methods of theoretical study and molecular dynamics simulation, we find that the calculated value of Tolman length is more than zero, and it decreases as the size is increased among the whole size range. The value of surface tension increases with the radius of the surface of tension increasing, which is consistent with Tolman’s theory. These conclusions are significant for studying the size dependence of the surface tension.     

The Poley absorption in liquid crystals

The far infrared torsional oscillatory absorption of a nematic liquid crystal has been isolated for the first time free of higher frequency proper modes. This has been achieved using a molecule specially synthesised for this purpose with a dipole moment engineered perpendicular to the long axis so that torsional oscillation about this axis modulates this component only. The far infra-red power absorption of the liquid crystal in the isotropic, nematic, solid and supercooled conditions is therefore a Poley absorption, i.e. the torsional oscillation about the rigid long axis of the liquid crystal molecule itself. The effect of phase changes on a macroscopic level is to sharpen and intensify this absorption. This is clear evidence to the effect that phase changes in liquid crystals are cooperative phenomena, the molecular librational dynamics about the long axis are little different from those in a regular molecular liquid.     

手性大孔磷酸镓Hit-5的水热合成与晶体结构

本文采用水热合成法制备了一个三维手性大孔开放骨架磷酸镓Ga16P16O75·4[1,6-C6H18N2]·[C2H10N2]·2H2O(简称Hit-5).反应起始原料摩尔配比为:1 GaOOH:15 H3PO4:7.5 H2N(CH2)6NH2:0.5 C2H8N2:555 H2O.Hit-5属正交晶系,P21212空间群,晶胞参数:a=0.8671(1)nm,b=1.7945(1)nm,c=0.9101(1)nm,β=108.33(1)°,V=1.3443(2)nm3,Z=4.Hit-5的骨架是由Ga3P3六聚体和Ga4P4八聚体两个不同的二级结构单元通过共顶点联接构成三维纳米孔结构,在[001]方向呈现16-元环孔道.     

Synthesis of new deazaflavins with planar chirality. Redox-induced “rope-skipping” racemization

New 5-deazaflavins with planar chirality (dFl(n)) were synthesized in which N(3) and O(2′α) in the 10-(2′-hydroxy)phenyl group were linked by a

chain (n=8,10). (+)-dFl(n=8) showed a large chiral discrimination in fluorescence quenching by (R)- and (S)-1,1′-bi-2- naphthol. (+)-dFl(n=10), which was optically stable at ambient conditions, racemized only when it was converted to the reduced form. This is the first example for redox-induced rope-skipping racemization.     

PdCl2(MeCN)2-catalyzed carbonylation of diethylamine with carbon dioxide: Selective synthesis of tetraethylurea and diethylformamide

The reaction of diethylamine with carbon dioxide (CO₂) with PdCl₂(MeCN)₂ as a catalyst gives tetraethylurea(1) or diethylformamide(2) selectively under mild reaction conditions by employing the PPh₃/CCl₄/MeCN and the HCOONa/methyl cellosolve systems, respectively.     

Regioselective aromatic ring functionalization of dopamine analogues

The selective aromatic ring functonalization of tetramethyl dopamine 2 at C₂ and C₅ was achieved via alkyllithium-induced carbanion formation at r.t. and −78° , respectively. The C-6 substitution was affected via palladium acetate mediated cyclometallation.