High‐performance liquid chromatographic column packings with different particle sizes: Chromatographic behavior for the quality analysis of HuanglianShangqing pill

The chromatographic separation of traditional Chinese medicines is still a highly challenging task in analytical science with respect to its hundreds and thousands of chemical compounds, while increase of separation efficiency can greatly improve the separation power of chromatographic column for traditional Chinese medicine. In this study, 13 bioactive components in HuanglianShangqing pill were selected as an index to optimize the separation conditions and evaluate the system suitability of three commercially available columns packed with 1.8, 3.5, and 5.0 μm particles. The chromatographic separations were obtained by the most appropriate Eclipse Plus C₁₈ column (100 × 2.1 mm, 3.5 μm) within 45 min using gradient elution with aqueous‐ammonium acetate (10 mmol/L, pH 5.0) and acetonitrile, at a flow rate of 0.3 mL/min and an operating temperature of 30°C. The quality of HuanglianShangqing pill was assessed through combining simultaneous quantification of 13 compounds with fingerprint analysis. For the qualitative analysis, mass spectrometry was used to confirm the 13 compounds. All the validation data conformed to the acceptable requirements. For the fingerprint analysis, 32 peaks were selected as the common peaks at 254 nm to evaluate the similarities among HuanglianShangqing pills obtained from ten manufacturers.     

Study on backward-facing step flow and heat transfer characteristics of hybrid nanofluids

Journal of Thermal Analysis and Calorimetry - As high heat dissipation has increasingly become the primary factor restricting the capability of electronic elements, and the high temperature of the...     

Effective optical path length investigation for cubic diffuse cavity as gas absorption cell

A simple cubic-shaped cavity with a high-diffuse-reflectivity inner coating as a novel gas detection cell was developed. The effective optical path length (EOPL) was evaluated by comparing the oxygen absorption signal in the cavity and in air based on tunable diode laser absorption spectroscopy. The law for a spherical cavity was applied and modified to a cubic cavity as a function of reflectivity ρ, port fraction f, and the side length. Single-pass average path length of the cubic cavity was 0.723(7) times the side length. EOPL can be modified conveniently by adjusting the parameters of the cavity.     

RECOVERY OF URANIURN FROM CARBONATE SOLUTIONS USING STRONGLY BASIC ANION EXCHANGER 3. THE MECHANISMS OF RECOVERY PROCESSES

INTRODUCTIONForthebinaryionexchangereactionmovingboundarymodelwasreported:(a)undertheassumptionofconstantvolumeofresinbeadsduringionexchange['--21,(b)withchangingsphericalvolumeofion...h..g...[3).Thismodelimpliesthreetypesofrate--determiningsteps:liquid--filmdiffusion,diffusionthroughtheso--calledinertlayerofthesorbent,andchemicalreactiontakingplaceattheboundaryoftheunreactednucleus.SongYlnjie.t.[4]carefullyrededucedsolutionscorrespondingtoabovethreetypesofrate-determiningsteps,andtheexpr…     

Preparation,characterization of crystalline zirconium phosphates and study on their acid stability and ion exchange behavior with uranyl ions

Two kinds of crystalline zirconium phosphate, - and -ZrP were prepared by direct method, and characterized by means of X-ray powder diffractometry, thermogravimetric analysis and pH titration. The total exchange capacity of -ZrP and -ZrP for Na⁺ ions determined by pH titration was 8.80 mmol/(g Zr(HPO₄)₂·6H₂O) and 3.80 mmol/(g NH₄ZrH(PO₄)₂·H₂O), respectively. The thermodynamic equilibrium constant of exchange reactions on -ZrP and on -ZrP at 25.0°C is 2.5 and 1.1, respectively. Although UO ₂ ²⁺ in solution is more preferred by -ZrP than by -ZrP, the selectivity of -ZrP for UO ₂ ²⁺ decreases with decreasing pH value while less effect of pH on the amount of UO ₂ ²⁺ ions exchanged to -ZrP has been found. It is also interesting to find out that both H⁺ and NH ₄ ⁺ ions in -ZrP can be replaced by UO ₂ ²⁺ ions existed in concentrated solution.     

基于自适应遗传算法的SVM参数优化

针对基于遗传算法支持向量机(SVM)训练时间较长以及分类精度较网格搜索法有所降低等问题,通过重新定义遗传算法参数的寻优范围,提出一种自适应遗传算法;该算法根据网格搜索法得到遗传算法参数的最佳寻优范围,然后遗传算法在这个范围内进行参数的精确寻优,最后得到分类的结果;这样不仅可以有效缩短训练时间,而且拥有更高的分类正确率;通过UCI中的10组经典数据集的实验结果可知,自适应遗传算法较之网格搜索法、 常规遗传算法、粒子群算法在训练时间上有较大的提升,并且拥有较高的分类准确率。     

Effect of Monomer Composition on the Performance of Polymer‐Stabilized Liquid Crystals with Two‐Step Photopolymerization

Polymer‐stabilized cholesteric liquid crystal (PSCLC) films with broadband reflection based on two‐step photopolymerization are fabricated. Owing to the helical twisting power (HTP) value of the chiral dopant (CD) decreasing with increasing temperature, PSCLC films with broadband reflection are obtained by two‐step polymerization anchoring helical pitch of different length at two different temperature points. The effect of monomer composition on the PSCLC reflection properties before and after polymerization was studied. The results show that the free‐radical monomers with appropriate concentration and cationic monomers with sufficient concentration are vital for the formation of PSCLC films with broadband reflection. In addition, the experiments show that the increase in the functionality and rigidity of the cationic monomer has a positive effect on the broadening of the reflection band. This study can provide guidance and reference for the selection of monomer species and concentration in PSCLC preparation. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2019 , 57, 1126–1132     

A Promising Mechanism for Photonic Spin Hall Effect and Refractive Index Sensing: Surface Exciton Polaritons

Surface polaritons are surface electromagnetic waves propagating along the surface of a medium, which play an important role in enhancing the photonic spin Hall effect (SHE). Among them, the successful excitation of surface exciton polaritons (SEPs) often requires cryogenic temperature, which limits their practical applications. In this contribution, a promising mechanism is presented for enhancing the photonic SHE by taking advantage of room-temperature SEPs in a prism-glass-TDBC-air configuration. By depositing the TDBC layer on plasmon active metal, the hybrid polariton, namely, surface plasmon exciton polariton (SPEP) can be observed, which gives rise to the further enhancement of photonic SHE. Furthermore, a refractive index sensor based on SEP (or SPEP) enhanced photonic SHE is proposed with the superior sensing performance. The results pave the way for the realization of giant photonic SHE in this simple and promising method, and offer the opportunity for developing highly sensitive optical sensors.     

氢键型碳纳米管增强自修复复合材料的制备和表征

使用低聚酸、二乙烯三胺以及尿素为原料,碳纳米管为增强剂,制备出兼具良好力学性能和室温(30 ℃)自修复性能的氢键型自修复复合材料,同时对材料通过氢键进行自修复的机制进行了合理推测。 首先,对不同碳纳米管添加量的自修复材料进行应力-应变性能测试。 结果发现,随着碳纳米管的添加,材料的应力、应变均有所提高,添加质量分数9%碳纳米管时,材料的应力达到4.1 MPa、应变达到6%以上。 对添加质量分数9%碳纳米管的自修复材料进行表面形态、自修复性能以及热稳定性能测试。 结果表明,碳纳米管与材料有良好的相容性,材料的表面与切面形态相似;在室温下自修复24 h,自修复效率达到100%;10次断裂-修复循环中自修复效率仍能保持90%以上;材料具有良好的热稳定性,最大失重速率下的温度为474.3 ℃。 为下一代类皮肤传感器以及可穿戴智能设备提供了一种选择,为未来该类型自修复聚合物复合材料在高拉伸强度领域的应用奠定了技术基础。     

Well-defined micropatterns of polymers prepared by controlled crystallization process

Surface confined recrystallization of highly-oriented polyethylene (PE) thin films realized by carbon-coating was utilized to control the morphological structure of ultrathin PE films. Selective carbon-coating with the help of a mask and subsequent recrystallization of the pre-oriented PE thin film lead to a partially structural control of the PE thin film in the coated domains. A fully structural control of the PE film is then fulfilled through a combination of surface confinement and heteroepitaxy of PE on the oriented poly(tetrafluroethylene) (PTFE) thin film. The thus obtained structure can serve as a template to induce pattern structures of a variety of other polymers through epitaxial growth. The poly(ε-caprolactone) (PCL) and poly(butylenes adipate) (PBA) micropattern thin films are shown in this paper as examples. These thin films exhibit different birefringence in different regions depending on the molecular orientation and may find potential applications in the fields of polarization-dependent display or storage.