Preparation of polypropylene/ethylene‐propylene‐diene terpolymer/nitrile rubber ternary thermoplastics vulcanizates with good mechanical properties and oil resistance by core‐shell dynamic vulcanization

As the most successful commercialized thermoplastic vulcanizates (TPVs), polypropylene (PP)/ethylene propylene rubber (EPDM) TPVs exhibit poor oil resistance. In this work, we prepared PP/EPDM/butadiene acrylonitrile rubber (NBR) ternary TPVs with good oil resistance using core‐shell dynamic vulcanization. According to the theoretical analysis of the spreading coefficient and the transmission electron microscopy results, the rubber phases exhibited a special core‐shell structure, in which the cross‐linkedNBR‐core was encapsulated by the EPDM‐shell. The core‐shell structure effectively improved the interfacial compatibility between PP and NBR phase as the EPDM‐shell could avoid the direct contact of them, thus improving the mechanical properties of the TPVs. For example, the PP/EPDM/NBR (40/30/30) ternary TPV showed enhanced tensile strength of 12.57 MPa, compared with 10.71 MPa of PP/EPDM (40/60) TPV and 11.11 MPa of PP/NBR (40/60) TPV, respectively. Moreover, the oil resistance of the TPVs was also improved. Compared with PP/EPDM TPV, the change rates in mass, volume, tensile strength and elongation at break of PP/EPDM/NBR TPV after oil immersion decreased by 42.18%, 48.69%, 52.68% and 28.77%, respectively.     

Catalytic Selective Dihydrosilylation of Internal Alkynes Enabled by Rare‐Earth Ate Complex

Hydrosilylation of alkynes generally yield vinylsilanes, which are inert to the further hydrosilylation because of the steric effects. Reported here is the first successful dihydrosilylation of aryl‐ and silyl‐substituted internal alkynes enabled by a rare‐earth ate complex to yield geminal bis‐ and tris(silanes), respectively. The lanthanum bis(amido) ate complex supported by an ene‐diamido ligand proved to be the ideal catalyst for this unprecedented transformation, while the same series of yttrium and samarium alkyl and samarium bis(amido) ate complexes exhibited poor activity and selectivity, indicating significant effects of the ionic size and ate structure of the rare‐earth catalysts.     

High‐Tc Enantiomeric Ferroelectrics Based on Homochiral Dabco‐derivatives (Dabco=1,4‐Diazabicyclo[2.2.2]octane)

1,4‐Diazabicyclo[2.2.2]octane (dabco) and its derivatives have been extensively utilized as building units of excellent molecular ferroelectrics for decades. However, the homochiral dabco‐based ferroelectric remains a blank. Herein, by adding a methyl (Me) group accompanied by the introduction of homochirality to the [H₂dabco]²⁺ in the non‐ferroelectric [H₂dabco][TFSA]₂ (TFSA=bis(trifluoromethylsulfonyl)ammonium), we successfully designed enantiomeric ferroelectrics [R and S‐2‐Me‐H₂dabco][TFSA]₂. The two enantiomers show two sequential phase transitions with transition temperature (T_c) as high as 405.8 K and 415.8 K, which is outstanding in both dabco‐based ferroelectrics and homochiral ferroelectrics. To our knowledge, [R and S‐2‐Me‐H₂dabco][TFSA]₂ are the first examples of dabco‐based homochiral ferroelectrics. This finding opens an avenue to construct dabco‐based homochiral ferroelectrics and will inspire the exploration of more eminent enantiomeric molecular ferroelectrics.     

Aligning retention time shifts in HPLC three‐dimensional spectra by icoshift approach combined with data arrangement methods and the release of a graphical user interface

High‐performance liquid chromatography coupled with photodiode array detection has been extensively applied in many fields and the peaks among the analyzed samples can be shifted due to the variations of instrumental and experimental conditions. In multivariate analysis, retention time alignment is an important pretreatment step. Hence, the shifted peaks in high‐performance liquid chromatography coupled with photodiode array detection three‐dimensional spectra should be aligned for further analysis. Being motivated by this purpose, the interval correlated shifting method combined with the proposed data arrangement methods are recommended and employed on high‐performance liquid chromatography coupled with photodiode array detection data as a demonstration. We validate the alignment performance of the proposed method through comparison the consistency of the retention time before and after alignment. The obtained results demonstrated that the proposed method is capable of successful aligning the employed data. Additionally, the interval correlated shifting method combined with the data arrangement modes is implemented in an easy‐to‐use graphical user interface environment and so can be operated easily by users not familiar with programming languages.     

Generalized Aifantis strain gradient plasticity model with internal length scale dependence on grain size,sample size and strain

Sediment-water interfaces are important interfaces for lakes, which are related to most environmental and ecological problems. Wind-induced waves cause secondary pollution via sediment resuspension. Since the coupling mechanism of water, resuspended sediments, and phosphorus affects the release of phosphorus (P) near the interface, a coupled model was explored for two sediment types with different adsorption-desorption capabilities to examine sediment resuspension and P release. The relationships among wind speed, wave characteristics, sediment distribution and P concentration were obtained. For different sediments, the unit sediment desorption release is negatively correlated with wind speed. When sediments are resuspended under low or moderate wind speed, the P concentration in the overlying water increases abruptly, hampering diffusion. P release exhibits the characteristics of concentrated release in a small region and changes the water environment rapidly.

     

扩大景深的波前编码成像系统特性分析

从空域和频域两个方面利用新的数学工具对扩大景深的波前编码成像系统的一些重要特性进行了阐释和分析。空域中,主要利用维格纳分布函数的正则投影来分析系统的点扩展函数对离焦像差的变化不敏感特性;频域中,则利用考纽螺线的图解方法来分析系统的光学传递函数对离焦像差的变化不敏感特性。简单讨论了波前编码成像技术所涉及的数字图像处理方法,并且用数值仿真实验验证了波前编码成像系统的这些优越特性。     

Novel stability condition for delayed fractional-order composite systems based on vector Lyapunov function

Nonlinear Dynamics - This paper proposes a novel stability condition for delayed fractional-order composite systems. First, we extend the vector Lyapunov function to the fractional-order systems to...     

Sensor configuration for distributed passive localization system in ocean acoustic field

In order to improve the localization accuracy of the distributed passive location system in the ocean acoustic field,a sensor configuration method is proposed b...     

Sagnac棱镜角公差与干涉光谱仪光谱分辨率的关系分析

根据干涉成像光谱仪光谱分辨率对角向差的要求,通过对实体Sagnac干涉仪结构和光路进行分析,从三个相互垂直的方向出发,研究了光谱分辨率和棱镜角公差之间存在的关系;并推导了满足光谱仪光谱分辨率要求的实体Sagnac干涉棱镜的角公差公式;用实例说明了关系式的应用方法,如果不考虑棱镜变形引起的色散及棱镜的面型误差和付氏镜的残余像差的影响,而只考虑棱镜的角误差对光谱分辨率的影响,则通常情况下干涉棱镜的角公差要求较严,约20″以内.     

棱镜自重变形对波面影响的研究

采用有限元方法分析了单棱镜在重力作用下三个典型位置的表面变形,对棱镜表面Φ425mm通光孔径轴向变形量进行Zernike多项式拟合,画出了相应的波差图,并确定设计方案.进一步选择Φ360 mm口径光束对双棱镜在几种典型相对位置下进行光线采样、追迹,计算得到不同情况下由于双棱镜自重变形引起的总波差.