Differential Entropy of Induced Random State Ensemble

International Journal of Theoretical Physics - In this paper, we will consider the exact calculation of differential entropy of induced random state ensemble by partial tracing a subsystem over...     

An innovative flower pollination algorithm for continuous optimization problem

The flower pollination algorithm (FPA) is a relatively new swarm optimization algorithm that inspired by the pollination phenomenon of natural phanerogam. Since its proposed, it has received widespread attention and been applied in various engineering fields. However, the FPA still has certain drawbacks, such as inadequate optimization precision and poor convergence. In this paper, an innovative flower pollination algorithm based on cloud mutation is proposed (CMFPA), which adds information of all dimensions in the global optimization stage and uses the designed cloud mutation method to redistribute the population center. To verify the performance of the CMFPA in solving continuous optimization problems, we test twenty-four well-known functions, composition functions of CEC2013 and all benchmark functions of CEC2017. The results demonstrate that the CMFPA has better performance compared with other state-of-the-art algorithms. In addition, the CMFPA is implemented for five constrained optimization problems in practical engineering, and the performance is compared with state-of-the-art algorithms to further prove the effectiveness and efficiency of the CMFPA.     

The optimization of hydrothermal process of MoS_2 nanosheets and their good microwave absorption performances

In this study,flower-like MoS_2 constructed by nanosheets was synthesized by a simple hydrothermal method.The hydrothermal process was optimized and the effects of hydrothermal condition,including reaction temperature,reaction time and the ratio of Mo source to S source(Mo:S) in precursor,on microwave absorption performances and dielectric properties were investigated.Our results showed that when the reaction temperature was 180℃,the reaction time was 18 h,and the Mo:S was 1:3.5,the synthesized MoS_2 had the best performance:Its minimum reflection loss could reach-55.78 dB,and the corresponding matching thickness was 2.30 mm with a wide effective bandwidth of 5.17 GHz.Further researches on the microwave absorption mechanism revealed that in addition to the destructive interference of electromagnetic waves,various polarization phenomena such as defect dipole polarization were the main reasons for microwave loss.We believe that MoS_2 is a candidate for a practical microwave absorbent.     

In-situ preparation and electrochromic properties of TiO2/PTPA-HTAN core-shell nanocomposite film

A new star-shaped structure conjugated microporous polymers, poly (2,8,14-tri[4-diphenyl-benzene]-hexaazatrinaphthylene) (PTPA-HATN), was designed and in-situ electrochemically polymerized on the surfaces of FTO electrodes with a directional alignment TiO₂ nanorod array to obtain TiO₂/PTPA-HATN core-shell nanocomposite films. Compared with the PTPA-HATN film, the TiO₂/PTPA-HATN composite film exhibits higher optical contrast and faster response time, with contrast of 57% at 783 nm, coloring time of 3.62 s and discoloring time of 2.55 s (43%, 4.63 s and 4.77 s for PTPA-HATN film, respectively). After 400 cycles, the contrast of nanocomposite film decreased by 28%, while the PTPA-HATN film basically lost its electrochromic properties. A simple three-layer EC prototype device based on TiO₂/PTPA-HATN nanocomposite film constructed with hydrogel electrolyte clearly shows color changes at different voltages. On the one hand, the formation of core-shell porous nanostructure of TiO₂/PTPA-HATN composite film provides a larger ion doping/de-doping interface, shortening the average diffusion length of ions. On the other hand, the large indented polymer-nanorods contact interface makes it difficult for the polymer to detach from the electrode, thus significantly improving the cyclic stability of the composite film.     

Iron carbonyl thioboronyls: effect of substitution of sulfur for oxygen in the viability of binuclear complexes toward dissociation reactions

The recent discovery of boronyl complexes of the type (R₃P)₂Pt(BO)X (R = cyclohexyl; X = halogen) makes of interest the chemistry of complexes of the related thioboronyl (BS) ligand. In this connection, the binuclear iron carbonyl complex Fe₂(BS)₂(CO)₈ is predicted by density functional theory to have a symmetrical unbridged structure similar to the valence isoelectronic Mn₂(CO)₁₀. Higher-energy unsymmetrical (OC)₅Fe → Fe(BS)₂(CO)₃ structures are also found as well as a doubly bridged Fe₂(BS)₂(CO)₆(µ-CO)₂ structure. The complex Fe₂(BS)₂(CO)₈ is predicted to be viable toward symmetrical dissociation into Fe(BS)(CO)₄ fragments. However, the unsymmetrical dissociation of Fe₂(BS)₂(CO)₈ into Fe(CO)₅ + Fe(BS)₂(CO)₃ is predicted to be exothermic by ~9 kcal mol^?1. The low-energy structures of the mononuclear Fe(BS)₂(CO)₃ include structures in which the two BS ligands have coupled to form a B₂S₂ ligand through B–B bond formation.     

An improved neuronal energy model that better captures of dynamic property of neuronal activity

Among the theories of neural information coding, the neural energy coding is more accessible to global coding features than traditional neural encoding. According to the shortcomings existing in the neuronal energy model, that is, the non-smooth nature of the energy curve, we proposed an improved neuronal energy model in this paper. The modified energy model is a good choice for establishment of the global model of brain function. And it is also the basis of energy calculation for functional cognitive neural networks in the future.     

Pt/ZnO 在室温水相无碱条件下绿色催化苯甲醇选择性氧化

醇类化合物选择性氧化是有机合成中一个非常重要的反应, 在精细化工领域具有重要应用. 而以水为绿色溶剂, 分子氧为绿色氧化剂实现醇类化合物选择性氧化是绿色化学领域的一大挑战. Pt 催化剂由于其优异的活化氧气和 C-H 键的能力在该反应中得到了广泛应用. 但是, 常规的 Pt 催化剂通常需要在较高温度和较高氧气压力以及加碱的条件下才能发挥作用, 从而引起了催化剂腐蚀等一系列问题. 从绿色化学角度出发, 进一步优化 Pt 催化剂, 让其能够在室温无碱条件下以空气为氧化剂选择性氧化醇类合成羰基化合物具有重要的研究价值和应用前景.本文通过化学还原法制备了 Pt/ZnO 催化剂, 系统研究了该催化剂在水相无碱条件下选择性氧化苯甲醇生成苯甲醛反应中的催化性能. X 射线电子衍射和透射电镜等结果表明, Pt 颗粒较小(3.2 ± 0.3 nm), 均匀分散在 ZnO 载体上; X 射线光电子能谱表明 ZnO 载体能够稳定 Pt 纳米颗粒表面的 Pt0物种. 上述催化剂在水相苯甲醇选择性氧化反应中, 在室温下即可催化空气高选择性氧化苯甲醇到苯甲醛 (选择性>99%), 并表现出比 Pt/SiO2, Pt/Al2O3, Pt/TiO2, Pt/Ca(Mg)-ZSM-5 等催化剂更为优异的催化活性. 这可归结于 Pt 和 ZnO 之间的协同作用. 该协同作用通过动力学实验和密度泛函理论计算 (DFT)得到了证实. 氧分压实验表明, 在以空气为氧化剂时, O2的活化并不是限制 Pt/ZnO 催化活性的关键因素, 而动力学同位素效应实验则证实了苯甲醇的 C-H 键活化是整个反应的决速步骤. 通过构建不同的理论模型, 分别计算了 Pt/ZnO 界面处以及纯 Pt 位点上苯甲醇选择性氧化的反应过程. 结果表明, 苯甲醇和氧气分子倾向于分别在 ZnO 和 Pt 上进行吸附, 随后由吸附的氧气分子来活化苯甲醇中的 C-H 键, 进而生成苯甲醛和水. 而当 ZnO 不参与苯甲醇的吸附活化时, 整个反应的活化能会大大提高, 表明 ZnO 和 Pt 之间的协同作用对于整个反应至关重要. 此外, Pt/ZnO 表现出非常优异的稳定性, 循环使用 4 次后, 催化剂结构以及催化活性没有显著变化.进一步向 Pt/ZnO 催化剂中引入少量 Bi 元素对 Pt 的电子结构进行修饰, 可以将 Pt/ZnO 的催化活性提高 3 倍. 所制备的 Pt/Bi-ZnO 复合物是目前报道的相同条件下催化苯甲醇选择性氧化反应转化频率 (45.1 h-1)最高的催化剂.