Construction of highly enantiopure β,β-diaryl substituted glycine containing two contiguous stereocenters via asymmetric 1,6-conjugate addition

Asymmetric construction of β,β-diaryl substituted glycine bearing two contiguous chiral centers remains a significant challenge. Herein, the application of the para-quinone methides (p-QMs) and Ni(II)- complex of glycine via 1,6-conjugate addition to achieve asymmetric synthesis of β,β-diaryl substituted glycine has been explored successfully. This protocol features operational simplicity, high diastereoselectivity, and recyclable chiral ligand, which provides a versatile approach to the synthesis of highly enantiopure β,β-diaryl substituted glycine.     

NIR analysis for batch process of ethanol precipitation coupled with a new calibration model updating strategy

Ethanol precipitation plays a major role in the pretreatment of Flos Lonicerae Japonicae of Qingkailing injection, and is also one of the most popular purification techniques in Chinese herbal medicines. In order to monitor and have a better understanding of the ethanol precipitation process, a PLS model was built based on NIR spectroscopy and HPLC analysis of chlorogenic acid content within the framework of FDA's PAT initiative. Nevertheless, due to the complex mechanism of and the raw materials’ natural variability introduced into the ethanol precipitation process, it was unable to foresee the variations in new batches which may jeopardize the robustness of the established model. Therefore, based on the simple interval calculation (SIC) theory, a new model expansion updating strategy which could continuously expand the variation coverage of the calibration model along with the batch proceeding of ethanol precipitation process was proposed. Effects of model updating were validated by an individual batch with 60 samples. After two times of updating, the root mean squared error of prediction (RMSEP) decreased from 0.268 mg mL⁻¹ to 0.199 mg mL⁻¹, while the insiders in the object status plot (OSP) increased from 44 to 58, demonstrating the good performance of the proposed approach.     

An enhanced analytical strategy integrating offline two-dimensional liquid chromatography with high-resolution accurate mass spectrometry and molecular networking: Comprehensive characterization of HuangLian JieDu Decoction as a case study

Comprehensive ingredient research is of great significance for understanding the effective material basis of herbal medicines, but due to the diversity and complexity of their phytochemicals, such research is challenging. Here, a multifaceted strategy was proposed to analyze and identify the composition of HuangLian JieDu Decoction based on offline two-dimensional liquid chromatography combined with ultraviolet detection and high-resolution mass spectrometry. Multiple components were separated by two-dimensional liquid chromatography, which consisted of hydrophilic interaction chromatography and reversed-phase liquid chromatography, and then further characterized by high-resolution mass spectrometry with a full mass spectrometry/precursor ion list/data-dependent secondary scan data acquisition method. For data processing, database screening and molecular networking were used to identify the components in HuangLian JieDu Decoction. The offline two-dimensional liquid chromatography combined with ultraviolet detection and a high-resolution mass spectrometry system showed good orthogonality of 76.35% and a high peak capacity of 5175, effectively separating multiple components. Finally, 527 compounds, including 164 alkaloids, 133 terpenoids, 88 flavonoids, 60 phenylpropanoids, 38 organic acids, and 44 other compounds, were characterized. This integrated approach is suitable for the comprehensive characterization of herbal medicines and other complex chemical systems.     

Influence of fluorescent dye on the linear polarization direction of stimulated Raman Stokes scattering in liquid‐core optical fibers

We present a simple analytical model to describe the stimulated Raman Stokes scattering (SRS) linear polarization spectroscopy of fluorescent dye solutions in liquid‐core optical fibers (LCOFs). In this scheme, the linear polarization direction of the pump pulse is set parallel to the y‐axis through a straight polarization‐maintaining LCOF, in which the energy of the total optical field is kept invariant, and different fluorescence dyes are used to generate different first‐order Stokes intensities. We demonstrate the SRS of all‐trans‐β‐carotene and fluorescein in carbon disulfide (CS₂) solutions due to the optical field‐induced reorientation effect, which makes the first‐order Stokes polarization direction rotate by an angle of 88° or 61°, respectively. This demonstrates the good agreement between the theory presented and the experiment. Copyright © 2010 John Wiley & Sons, Ltd.     

三重介质油藏模型及其Laplace空间解

本文建立了裂缝、洞与井筒连通的三重介质油藏的试井解释模型,利用Laplace变换和构造通解法,研究了这一类线性偏微分方程的边值问题,得到了其Laplace空间解,为裂缝、洞与井筒连通油藏的试井分析提供了坚实的理论基础。     

Conversion of ZnO nanorod arrays into ZnO/ZnS nanocable and ZnS nanotube arrays via an in situ chemistry strategy

Vertically aligned ZnO nanorods with uniform diameter and length have been synthesized on a zinc foil substrate with ammonium persulfate as oxidant via a facile, larger scale production and inexpensively synthesized method without any templates or additives. SEM and XRD studies indicate that ZnO nanorods are well-oriented along the c-axis. The PL spectrum indicates that our as-synthesized ZnO nanorods with a stronger and wider green emission are promising candidates as electron nanoconductors in nano-optoelectronic devices. Furthermore, by an effective thioglycolic acid-assisted solution route, well-aligned ZnO/ZnS nanocable and ZnS nanotube arrays have been successfully synthesized. ZnS nanotubes show a perfect hexagonal and obvious tubular shape. Our present strategy shows mild growth conditions and good reproducibility.     

Morphosynthesis of hierarchical hydrozincite with tunable surface architectures and hollow zinc oxide

Hydrozincite (Zn5(CO3)2(OH)6) microspheres with a tunable surface architecture have been successfully synthesized via a homogeneous precipitation method under solvothermal conditions. For a smooth hydrozincite microsphere, various building blocks such as nanocubes, nanorods, and nanosheets are arranged to cover a spherical surface by concisely controlling reaction time and the volume of ethylene glycol. Hexagonal Zn5(CO3)2(OH)6 with nanostep structures are also prepared without any additives. The hollow ZnO microspheres with a porous surface have been successfully fabricated via a solution-based method by the room-temperature treatment of filled Zn5(CO3)2(OH)6 microspheres composed of nanocubes. A possible growth mechanism of these hollow ZnO microspheres is proposed. The similar filled ZnO microspheres can also be obtained by a direct pyrolysis of Zn5(CO3)2(OH)6 microspheres composed of nanocubes at 450 degrees C.     

EXACT SOLUTIONS OF SOME FIFTH——ORDER NONLINEAR EQUATIONS

Abstract. To solve the nonlinear partial differential equations is changed into solving some alge-braic equations by using the function U to be expressed as linear independent functions. Thenew soliton and periodic solutions of some fifth-order nonlinear partial differential equations areobtained.     

扩充的Hermite—Fejer插值算子平均收敛性

讨论了以Ｊａｃｏｂｉ正交多项式零点为插值结点的扩充Ｈｅｒｍｉｔｅ－Ｆｅｊｅｒ插值算子在Ｌｕ＾ｐ空间的平均收敛性。首先给出了算子加权平均收敛的条件,进一步得到了收敛阶。     

悬停状态下无铰式旋翼动力学参数试验研究

旋翼结构参数及动力学参数对旋翼动力学特性有着重要影响。随着旋翼结构型式的不断更新,在旋翼设计中需要考虑的动力学参数也相应增加,从而使旋翼的动力学问题更加复杂化。本文通过在２米旋翼试验台上进行的试验,用测量桨叶频响函数和稳态响应的方法研究了悬停状态预锥角、预掠角和总距角等旋翼结构参数对桨叶固有特性及气动弹性稳定性的影响规律,并同计算结果进行了比较,得到了一些对旋翼设计有实用意义的结论