含氟丙烯酸酯树脂的合成及其在氟碳涂料中的应用

以过氧化苯甲酰(BPO)为引发剂,将甲基丙烯酸十二氟庚酯(RfAA)、丙烯酸丁酯(BA)、丙烯酸羟丙酯(HPAA)、丙烯酸(AA)和苯乙烯(ST)采用溶液聚合方法合成一种含氟丙烯酸酯树脂(PFBSH),并通过红外光谱(IR)对PFBSH进行了结构表征。将此树脂应用在双组份氟碳涂料中,该氟碳涂层的水接触角达到110.5°,其附着力、硬度、光泽和耐水性等都获得了令人满意的应用效果。另外讨论了固化温度和纳米TiO2对涂料应用性能的影响。     

人道价值论与天道价值论述评

在人和自然应建立一种什么样的关系问题上,国内学者持两种观点即人道价值论和天道价值论.人道价值论强调人的自由、权利、尊严等主体价值,认为人道价值高于效用价值,有其重要的意义,但过分跨大人的主体价值会导向强化的人类中心主义.天道价值提出以自然本体的名义阐述价值,认为天道价值高于人道价值,天道价值有助于抑制强化的人类中心主义,但又有泛主体化倾向,文中试图纠正二者的局限,实现人道价值和天道之间的和解,建立一种适宜的人类中心主义.     

界面相容性对PP/秸秆复合材料性能的影响

以复合材料界面相容性理论为基础,通过改变偶联剂的种类和含量研究木塑界面相容性对PP/秸秆复合材料力学性能的影响。通过力学性能测试和SEM照片比对发现:单独加入硅烷、钛酸酯或DN-302时,复合材料的界面相容性均有所改善,力学性能提高。在上述3种偶联剂分别加入MAPP作为组合偶联剂使用后,各项力学性能提高明显,其中以3%的钛酸酯加上3%的MAPP作为偶联剂时,复合材料的力学性能最好。     

Effect of reoxidation on positive temperature coefficient of resistance behavior for BaTiO3-K0.5Bi0.5TiO3 ceramics

As a positive temperature coefficient of resistivity (PTCR) material, (1-x)BaTiO₃-xK_0.5Bi_0.5TiO₃ (BT-KBT, 0.05≦ x ≦0.15) ceramics without any donor doping were prepared by a conventional oxide mixing method. All samples were sintered in an Ar atmosphere at 1280?~?1350°C, subsequently, reoxidized at 800?~?1100°C in a gas mixture (99 %Ar–1 %O₂). The PTCR behavior of BT-KBT ceramics were investigated in terms of KBT content, reoxidation temperature and time. The results showed that the BT-KBT ceramics exhibited an abrupt increase in their resistivity near the Curie temperature (Tc) after annealing in gas mixture, Tc of 0.9BT-0.1KBT ceramic was shifted to a higher temperature (~150°C). Furthermore, the room-temperature resistivity (ρ_RT) of ceramic samples sintered in Ar and reoxidized in a gas mixture decreased to 10² Ω·cm. The jump in resistivity (maximum resistivity [ρ_max]/minimum resistivity [ρ_min]) was enhanced by three orders of magnitude through a suitable reduction–reoxidation method without sacrificing the ρ_RT.     

Electrocatalytic oxidation of cyclohexanol on a nickel oxyhydroxide modified nickel electrode in alkaline solutions

Electrocatalytic oxidation of cyclohexanol was investigated with cyclic voltammograms, linear galvanic voltammograms and chronoamperometric responses on a nickel oxyhydroxide modified nickel (NOMN) electrode prepared by cycling the potential of a nickel electrode in the potential range of 0.1 V to 0.6 V (vs SCE) in alkaline solutions. It was found that cyclohexanol was oxidized by NiOOH generated with further electrochemical oxidation of nickel hydroxide during the anodic potential sweep. One of the products of the reaction between cyclohexanol and NiOOH was Ni(OH)₂ which was subsequently oxidized to NiOOH on the anode. This resulted in the appearance of a new anodic peak in cyclic voltammograms compared with the absence of cyclohexanol and this anodic peak strongly depends upon potential scan rates and cyclohexanol concentrations. In addition, the presence of cyclohexanol in NaOH solutions also lead to the decrease of anodic potentials in linear galvanic voltammetric responses and the increase of current densities in chronoamperometric curves. Results showed that the oxidation of cyclohexanol on the NOMN electrode follows the catalytic reaction mechanism.     

PhDD: A new pharmacophore-based de novo design method of drug-like molecules combined with assessment of synthetic accessibility

This account describes a new pharmacophore-based de novo design method of drug-like molecules (PhDD). The method PhDD first generates a set of new molecules that completely conform to the requirements of a given pharmacophore model, followed by a series of assessments to the generated molecules, including assessments of drug-likeness, bioactivity, and synthetic accessibility. PhDD is tested on three typical examples, namely, pharmacophore hypotheses of histone deacetylase (HDAC), cyclin-dependent kinase 2 (CDK2) and HIV-1 integrase (IN) inhibitors. The test results demonstrate that PhDD is able to generate molecules with novel structures but having similar biological functions with existing inhibitors. The validity of PhDD together with its ability of assessing synthetic accessibility makes it a useful tool in rational drug design.     

不同阶混沌Colpitts电路系统的同步

针对四阶和三阶混沌Colpitts电路系统,利用Active方法对系统的同步进行了研究,实现了不同阶Colpitts电路系统在超高频域内的主从混沌同步。同时对系统在存在内部参数扰动和外部干扰的情况下,分析了控制器的鲁棒性。最后通过数值示例进行仿真,对文中论述进行了强有力的验证。     

Achieving high energy storage properties in perovskite oxide via high-entropy design

In recent years, “high-entropy” materials have attracted great attention in various fields due to their unique design concepts and crystal structures. The definition of high-entropy is also more diverse, gradually expanding from a single phase with an equal molar ratio to a multi-phase with a non-equimolar ratio. This study selected (Na_0.2Bi_0.2Ba_0.2Sr_0.2Ca_0.2)TiO₃ high entropy ceramics with excellent relaxation behavior. The A-site elements are divided into (x = Na, Bi, Ba) and ((1-3x)/2 = Sr, Ca) according to their inherent properties. A novel ABO₃ structural energy storage ceramics (NaBaBi)_x(SrCa)_(1-3x)/2TiO₃ (x = 0.19, 0.195, 0.2, 0.205 and 0.21) was successfully fabricated using the high entropy design concept. The ferroelectric and dielectric properties of non-equimolar ratio high-entropy ceramics were studied in detail. It was found that the dielectric constant of ∼4920 and the recoverable energy storage density of 3.86 J/cm³ (at 335 kV/cm) can be achieved simultaneously at x = 0.205. The results indicate that the design concept of high-entropy materials with a non-equal molar ratio is an effective means to achieve distinguished energy storage performance in lead-free ceramics.     

Optimized energy storage performance in BF-BT-based lead-free ferroelectric ceramics with local compositional fluctuation

BiFeO₃-based lead-free ferroelectric is considered a potential candidate for energy storage applications owing to its high spontaneous polarization. To tackle the compromise between high polarization and energy storage density, NaNbO₃ (NN) was introduced into 0.7BiFeO₃-0.3Ba(Hf_0.05Ti_0.95)O₃ (BF-BHfT) ceramics, where Nb⁵⁺ ions enter the BF-BHfT lattices and enhance resistivity, while Na⁺ ions occupied on the A-sites and smash the long-range ferroelectric order into polar nanoregions. Consequently, the ceramics could maintain high maximum polarization and low remanent polarization. High recoverable energy density (W_rec) of 5.2 J/cm³ and efficiency (88%) were recorded in 0.53BF-0.3BHfT-0.17NN ceramics. Besides, it exhibited good thermostability up to 120 °C (W_rec variation < 5%), frequency stability from 10 to 200 Hz (W_rec variation < 7%) and excellent fatigue resistance after 10⁴ cycles (W_rec variation < 0.2%). Under different electric fields the efficiency still maintains nearly constant. In charge-discharge test a W_dis of 3.7 J/cm³ was recorded, which proved 0.5³BF-0.3BHfT-0.17NN ceramics a promising candidate for energy storage applications.     

Ultra-fast high-temperature synthesis and densification of high-entropy diborides and diboride-carbide ceramics

The strong covalent bonds and low self-diffusion coefficients of high-entropy diboride (HEBs) and diboride-carbide (HEB-HEC) ceramics render their densification difficult, which limits their applications. Here, we used an ultra-fast high-temperature sintering technique to synthesize and densify several HEBs and HEB-HEC (containing 5–8 cations) ceramics within an isothermal duration of 1 min and a total sintering period of 6 min. All ceramics formed a single-phase or dual-phase high-entropy solid solution, and showed high density, high hardness and good fracture toughness. The rapid densification mechanisms were determined, and the preferential occupancy of metal cations in HEB and HEC phases was explained using a simplified ideal solution model. A good fracture toughness in the range of 3.6–5.4 MPa·m^1/2 resulted from crack deflection or blunting and bridging of the rod-like diboride or boron-rich phase. This paper presents a simple, economical, and efficient method for the synthesis and densification of high-entropy ceramics and other advanced materials.