加速溶剂萃取–液相色谱法测定五灵脂药材中原儿茶酸的含量

建立了五灵脂中原儿茶酸含量的测定方法。利用加速溶剂萃取仪(ASE),以75%乙醇水溶液提取样品中的待测物,用Diamosil C18(4.6 mm×250 mm,5.0μm)色谱柱在梯度洗脱条件下分离待测物,外标法定量。原儿茶酸的线性范围为0.1~10.0 mg/L,相关系数r=0.9998。方法的回收率为83%~107%,测定结果的相对标准偏差为4.6%~10.5%,方法的定量限为1.0 mg/kg。该方法操作简便、快速,提取效率高,适用于检测和分析五灵脂中原儿茶酸的含量。     

Two New Neolignans from the Stems of Syringa pinnatifolia Hemsl. var. alashanensis

Two new neolignans, syripinnalignins A and B ( 1 and 2 , resp.), were isolated from the 95% EtOH extract of the stem of Syringa pinnatifolia Hemsl . var. alashanensis. The structures of 1 and 2 were elucidated by spectroscopic methods, including UV, IR, HR‐ESI‐MS, and extensive 1D‐ and 2D‐NMR techniques.     

Polydopamine-Assisted Rapid One-Step Immobilization of L-Arginine in Capillary as Immobilized Chiral Ligands for Enantioseparation of Dansyl Amino Acids by Chiral Ligand Exchange Capillary Electrochromatography

Herein, a novel L-arginine (L-Arg)-modified polydopamine (PDA)-coated capillary (PDA/L-Arg@capillary) was firstly fabricated via the basic amino-acid-induced PDA co-deposition strategy and employed to constitute a new chiral ligand exchange capillary electrochromatography (CLE-CEC) method for the high-performance enantioseparation of D,L-amino acids (D,L-AAs) with L-Arg as the immobilized chiral ligand coordinating with the central metal ion Zn(II) as running buffer. Assisted by hydrothermal treatment, the robust immobilization of L-Arg on the capillary inner wall could be facilely achieved within 1 h, prominently improving the synthesis efficiency and simplifying the preparation procedure. The successful preparation of PDA/L-Arg coatings in the capillary was systematically characterized and confirmed using several methods. In comparison with bare and PDA-functionalized capillaries, the enantioseparation capability of the presented CLE-CEC system was significantly enhanced. Eight D,L-AAs were completely separated and three pairs were partially separated under the optimal conditions. The prepared PDA/L-Arg@capillary showed good repeatability and stability. The potential mechanism of the greatly enhanced enantioseparation performance obtained by PDA/L-Arg@capillary was also explored. Moreover, the proposed method was further utilized for studying the enzyme kinetics of L-glutamic dehydrogenase, exhibiting its promising prospects in enzyme assays and other related applications.     

The Alleviating Effect of Lagerstroemia indica Flower Extract on Stretch Marks through Regulation of Mast Cells

Striae distensae (SD) or stretch marks are common linear scars of atrophic skin with disintegrating extracellular matrix (ECM) structures. Although fibroblasts contribute to the construction of ECM structure in SD, some studies have reported that mast cell degranulation causes the disruption of ECM in early SD lesions. Lagerstroemia indica flower (LIF) has traditionally been used in India as a diuretic. However, little is known about the effect and molecular action of Lagerstroemia indica flower extract (LIFE) on alleviating SD. This study evaluated the effects of LIFE on mast cell degranulation and the synthesis of ECM components in fibroblasts. LIFE inhibits the adhesion of rat basophilic leukemia (RBL) cells, RBL-2H3 on fibronectin (FN) and the expression of integrin, a receptor for FN, thereby reducing focal adhesion kinase (FAK) phosphorylation. In addition, LIFE attenuated the allergen-induced granules and cytokine interleukin 3 (IL-3) through the adhesion with FN. Moreover, the conditioned medium (CM) of activated mast cells decreases the synthesis of ECM components, and LIFE restores the abnormal expressions induced by activated mast cells. These results demonstrate that LIFE suppresses FN-induced mast cell activation and promotes the synthesis of ECM components in fibroblast, which indicates that LIFE may be a useful cosmetic agent for SD treatment.     

调查问卷中含缺失数据的等级变量的补缺方法

讨论了调查问卷中等级变量缺失数据的补缺问题.基于多元统计学理论,并结合总体趋势和个体偏差,提出一种新的补缺方法,方法使得补缺值更加准确、真实,并且将此方法扩展到变量等级数不相等的调查问卷之中.     

热图法测量激光强度时空分布的重构理论研究

为了把量热法应用于远场激光强度时空分布测量,研究了基于热像仪靶面温度测量反演入射激光强度时空分布的重构理论。针对背光面两种不同边界条件(对流-辐射热流边界和恒定温度边界)推导出了由靶面温度分布反演激光束时空分布的重构表达式。获得的分析表达式对广泛的材料具有适用性。通过引入广义参量F0=α/L2,分别就F0》1和F0《1情况给出了重构近似表达式,并对满足F0》1条件的回推算法进行了数值模拟验证。数值结果表明,两种背光面边界条件下回推得到的激光束时空分布与原始激光束达到了很好的一致,但存在一与靶材傅里叶数相关的最小起始回推时间τ0。成果可用于强激光远场参量测量设备的研制。     

Flow characteristics of nonspherical granular materials simulated with multi-superquadric elements

The superquadric equation is typically used to mathematically describe nonspherical particles and construct particle shapes with different surface sharpness and aspect ratios.However,nonspherical elements constructed using the superquadric equation are strictly convex,limiting their engineering application.In this study,a multi-superquadric model based on a superquadric equation is developed.The model combines several superquadric elements that can be used to construct concave and convex particle shapes.Four tests are performed to examine the applicability of the multi-superquadric approach.The first involves a comparison of theoretical results for a single spherocylinder impacting a flat wall.The second involves the formation of a nonspherical granular bed.The third investigates the effects of the particle shape on the hopper discharge and angle of repose.The final test evaluates the mixing behaviors of granular materials within a horizontally rotating drum.These tests demonstrate the applicability of the multi-superquadric approach to nonspherical granular systems.Furthermore,the effects of particle shape on the packing density,discharge rate,angle of repose,and Lacey mixing index are discussed.Results indicate that concave particles have a lower packing density,flow rate,and mixing rate and higher angles of repose than convex particles.Interlocking of elements becomes more pronounced for concave particles and results in local cluster structures,thereby enhancing the stability of granular systems and limiting sliding or rotation between nonspherical particles.     

Tl系超导薄膜金属涂层的生长与特性研究

我们研究了Tl-2212超导薄膜在带有YSZ/CeO2缓冲层和带有CeO2/YSZ/CeO2缓冲层的Ni金属RABiTS基带上的生长情况.基带上的缓冲层是采用PLD方法制备的,Tl-2212薄膜的制备采用了磁控溅射和后热处理两步方法.XRD 实验结果表明,Tl-2212薄膜都具有很好的C轴垂直于膜面的织构,并具有双向外延生长特性.在CeO2/YSZ/CeO2/Ni基带上制作的Tl-2212薄膜的Tc达到102.8 K,Jc(77 K,0 T)达到2.6 MA/cm2;在YSZ/CeO2/Ni基带上薄膜Tc可达97.7 K,Jc(77 K,0 T)也可以达到0.45 MA/cm2.     

Quantum Anti-Zeno Effect in Nuclear Decay

The acceleration of decay induced by frequency measurements,namely the quantum anti-Zeno effect(AZE),was first predicted by Kofman and Kurizki [Nature 405(2000) 546].The effect of the frequency measurements on nuclear β decay rate is analyzed based on the time-dependent perturbation theory.We present a detailed calculation of the decay rates of ~3H,~(60)Co(β~-type),~(22)Na,~(106)Ag(β~+ type) and ~(18)F,~(57)Co and ~(111)Sn(EC type)under frequency measurements.It is found that the effects of frequency measurements on the decay rates of β~+and β~-cases are different from the case of EC,and the smaller the β decay energy is,the more favorable it is to observe the AZE in experiment.Based on our analysis,it is suggested that possible experimental candidates should have a small decay energy and a reasonable half life(such as ~3H) for observing the AZE in β decay.     

Thermal stress reduction of GaAs epitaxial growth on V-groove patterned Si substrates

We investigate the thermal stresses for GaAs layers grown on V-groove patterned Si substrates by the finite-element method. The results show that the thermal stress distribution near the interface in a patterned substrate is nonuniform,which is far different from that in a planar substrate. Comparing with the planar substrate, the thermal stress is significantly reduced for the Ga As layer on the patterned substrate. The effects of the width of the V-groove, the thickness, and the width of the SiO₂ mask on the thermal stress are studied. It is found that the SiO₂ mask and V-groove play a crucial role in the stress of the Ga As layer on Si substrate. The results indicate that when the width of V-groove is 50 nm, the width and the thickness of the SiO₂ mask are both 100 nm, the Ga As layer is subjected to the minimum stress. Furthermore,Comparing with the planar substrate, the average stress of the Ga As epitaxial layer in the growth window region of the patterned substrate is reduced by 90%. These findings are useful in the optimal designing of growing high-quality Ga As films on patterned Si substrates.