运用三维离散元技术模拟落锤撞击下奥克托今颗粒的点火燃烧过程

炸药颗粒的点火燃烧过程一直是人们关注的热点问题。近年来，三维离散元技术在中尺度观测颗粒材料的动力学过程中拥有显著优势。炸药燃烧属于颗粒材料的反应动力学，运用三维离散元技术(DM3)可以有效地观测炸药燃烧传播的过程。以奥克托今(HMX)颗粒为例，本文成功模拟并观测到了HMX颗粒的燃烧反应程度，确定了颗粒开始燃烧反应的时间，以及燃烧反应传播的时间。同时，结合落锤冲击颗粒的三维图像以及其表观压强和放热功率，得到了HMX颗粒燃烧反应、燃烧传播的整个反应动力学过程，包括颗粒在冲击加载下碎化塑性变形的过程，颗粒燃烧反应放热的过程，落锤回弹颗粒喷射的过程等。同时，进一步说明了尖顶颗粒更利于颗粒点火，平顶颗粒有抑制颗粒点火的能力。     

New soft porous frameworks based on lambda-zirconium phosphate and aliphatic dicarboxylates: Synthesis and structural characterization

New dicarboxylate-functionalized pillared materials with a general formula of λ-ZrPO₄(OH)_1-x(OOC(CH₂)_nCOO)_x/2(dmso) (n=6, 8 and 10) have been prepared by post-synthesis modification of the inorganic layers of λ-zirconium phosphate (λ-ZrP), where the superficial Chloride monovalent anionic ligands of λ-layer are partially exchanged with the divalent anionic ligands of a series of long-chain aliphatic dicarboxylic acids, namely octanedioic acid, decanedioic acid and dodecanedioic acid. The synthesized materials are characterized by X-ray diffractometry, FT-IR spectrophotometry, elemental and thermogravimetric analyses. The X-ray diffraction patterns show that the obtained solid phases are pure. Furthermore, the interlayer distance of λ-ZrP systematically increases from 1.02 to 1.59 nm as a result of the incorporation of the mentioned acids inside the interlayer gallery.     

Study of blood collection and sample preparation for analysis of vitamin D and its metabolites by liquid chromatography–tandem mass spectrometry

The analysis of vitamin D status, with special emphasis on 25-hydroxyvitamin D and 1,25-dihydroxyvitamin D, is gaining interest in clinical studies due to the classical and non-classical effects attributed to this prohormone. In this research, the influence of the two steps preceding determination (viz. sample collection and preparation) on the quantitative analysis of vitamin D and its more important metabolites has been studied. Two preparation approaches, deproteination and solid-phase extraction (SPE), have been evaluated in terms of sensitivity to delimit their application, thus establishing that detection of 1,25-dihydroxyvitamin D cannot be addressed by protein precipitation. Concerning sample collection, serum and plasma reported high accuracy (above 83.3%) for vitamin D and metabolites, while precision, expressed as relative standard deviation, was below 12.9% for all analytes in both samples. Statistical analysis revealed that serum and plasma provided similar physiological levels for vitamin D₃, 24,25-dihydroxyvitamin D₃ and 25-hydroxyvitamin D₃, while significantly different levels were obtained for 1,25-dihydroxyvitamin D₃, always higher in plasma than in serum. Sample collection and treatment have proved to be significant in the analysis of vitamin D and its relevant metabolites.     

Sensitive method for the determination of paricalcitol by liquid chromatography and mass spectrometry and its application to a clinical pharmacokinetic study

A highly sensitive, specific and rapid LC‐ESI‐MS/MS method has been developed and validated for the quantification of paricalcitol (PAR) in human plasma (500 μL) using paricalcitol‐d₆ (PAR‐d₆) as an internal standard (IS) as per regulatory guidelines. A liquid–liquid extraction method was used to extract the analyte and IS from human plasma. Chromatography was achieved on Zorbax SB C₁₈ column using an isocratic mobile phase in a gradient flow. The total chromatographic run time was 6.0 min and the elution of PAR and PAR‐d₆ occurred at ~2.6 min. A linear response function was established for the range of concentrations 10–500 pg/mL in human plasma. The intra‐ and inter‐day accuracy and precision values for PAR met the acceptance criteria. The validated assay was applied to quantitate PAR concentrations in human plasma following oral administration of 4 µg capsules to humans. Copyright © 2014 John Wiley & Sons, Ltd.     

基于石墨烯独特生物界面效应的功能化载体研究进展

二维石墨烯及其衍生物与生物界面的相互作用, 展现出相比于传统维度粒子截然不同的特性, 为功能化医药载体的设计开发提供了潜力策略. 除了优异的电学、热学、光学等性能外, 石墨烯的独特的二维性质, 可以引起细胞更强的应激反应, 包括与细胞膜发生水平摩擦/竖直嵌入/三明治超级结构、选择性被细胞内吞、胞内限域折叠、引发细胞自噬以及隐形活化效应. 基于上述独特界面效应以及理论模拟机制, 对石墨烯进行合理设计, 可在保障安全性的前提下, 满足药物递送、疫苗佐剂、成像传感、光热治疗等需求. 本综述结合课题组近10年在(氧化)石墨烯与生物界面效应、微观作用机理及应用开发方面的系统研究工作, 同时涵盖了国际最新进展, 以期为石墨烯高效、安全体系的设计、构建和应用, 提供理论依据和前瞻性预测.     

Uniform stability of semilinear wave equations with arbitrary local memory effects versus frictional dampings

This paper is concerned with the mixed initial–boundary value problem for semilinear wave equations with complementary frictional dampings and memory effects. We successfully establish uniform exponential and polynomial decay rates for the solutions to this initial–boundary value problem under much weak conditions concerning memory effects. More specifically, we obtain the exponential and polynomial decay rates after removing the fundamental condition that the memory-effect region includes a part of the system boundary, while the condition is a necessity in the previous literature; moreover, for the polynomial decay rates we only assume minimal conditions on the memory kernel function g, without the usual assumption of $g^{\prime }$ controlled by g.     

Analysis of a Cahn–Hilliard–Brinkman model for tumour growth with chemotaxis

Phase field models recently gained a lot of interest in the context of tumour growth models. Typically Darcy-type flow models are coupled to Cahn–Hilliard equations. However, often Stokes or Brinkman flows are more appropriate flow models. We introduce and mathematically analyse a new Cahn–Hilliard–Brinkman model for tumour growth allowing for chemotaxis. Outflow boundary conditions are considered in order not to influence tumour growth by artificial boundary conditions. Existence of global-in-time weak solutions is shown in a very general setting.     

Perturbative manifolds and the Noether generators of nth-order Poisson equations

A manifold that contains small perturbations will induce a perturbed partial differential equation. The partial differential equation that we select is the Poisson equation – in order to explore the interplay between the geometry of the manifold and the perturbations. Specifically, we show how the problem of symmetry determination, for higher-order perturbations, can be elegantly expressed via geometric conditions.     

Corrigendum to “Maximal linear groups induced on the Frattini quotient of a p-group” [J. Pure Appl. Algebra 222 (10) (2018) 2931–2951]

We give a correction to Fig. 1 and supporting text published in the paper: ‘Maximal linear groups induced on the Frattini quotient of a p-group’, J. Pure Appl. Algebra 222 (10) (2018) 2931–2951.     

The behavior of differential forms under purely inseparable extensions

Let F be a field of characteristic 2. In this paper we give a complete computation of the kernel of the homomorphism $H_2^{m+1}(F)?H_2^{m+1}(L)$ induced by scalar extension, where $L/F$ is a purely inseparable extension (of any degree), $H_2^{m+1}(F)$ is the cokernel of the Artin–Schreier operator $?:{\mathrm{\Omega }}_F^m?{\mathrm{\Omega }}_F^m/\mathrm{d}{\mathrm{\Omega }}_F^{m?1}$ given by: $x\frac{\mathrm{d}{x}_1}{x_1}\wedge ?\wedge \frac{\mathrm{d}{x}_m}{x_m}?(x^2?x)\frac{\mathrm{d}{x}_1}{x_1}\wedge ?\wedge \frac{\mathrm{d}{x}_m}{x_m}+\mathrm{d}{\mathrm{\Omega }}_F^{m?1}$, where ${\mathrm{\Omega }}_F^m$ is the space of absolute m-differential forms over F and d is the differential operator. Other related results are included.