Development and Optimization of Broadband Acoustic Metamaterial Absorber Based on Parallel–Connection Square Helmholtz Resonators

An acoustic metamaterial absorber of parallel–connection square Helmholtz resonators is proposed in this study, and its sound absorption coefficients are optimized to reduce the noise for the given conditions in the factory. A two–dimensional equivalent simulation model is built to obtain the initial value of parameters and a three–dimensional finite element model is constructed to simulate the sound absorption performance of the metamaterial cell, which aims to improve the research efficiency. The optimal parameters of metamaterial cells are obtained through the particle swarm optimization algorithm, and its effectiveness and accuracy are validated through preparing the experimental sample using 3D printing and measuring the sound absorption coefficient by the standing wave tube detection. The consistency between the experimental data and simulation data verifies feasibility of the proposed optimization method and usefulness of the developed acoustic metamaterial absorber, and the desired sound absorption performances for given conditions are achieved. The experimental results prove that parallel–connection square Helmholtz resonators can achieve an adjustable frequency spectrum for the low frequency noise control by parameter optimization, which is propitious to promote its application in reducing the noise in the factory.     

心力衰竭对门静脉频谱形态的影响

目的探讨心力衰竭对门静脉频谱形态的影响,摸索超声检查评价心功能的新途径。方法选取临床Ⅰ～Ⅲ度心力衰竭患者60例,按心衰竭程度分组,每组各20例;健康对照组20例。排除肝脏及门静脉、下腔静脉病变。经右侧肋间及剑突下探查门静脉,在取得门静脉清晰二维切面图像后,记录1～3个呼吸周期中的门静脉频谱,观察频谱形态,记录各组不同门静脉频谱形态的例数,所获资料采用统计软件SPSS11.0处理。结果健康对照组门静脉频谱均表现为单向连续频谱,各心力衰竭组出现不同程度的门静脉收缩末期反向血流,Ⅲ度心力衰竭组门静脉频谱多出现恒定的收缩末期反向血流。结论心力衰竭可导致门静脉频谱形态异常,观察门静脉频谱形态,可作为判断心力衰竭程度的辅助依据。     

Effect of Clopidogrel on Platelet Membrane CD40 Ligand in Coronary Artery Disease Patients Undertaking Percutaneous Coronary Intervention

Objectives To investigate the change and clinical significance of clopidogrel on platelet membrane CD40L in coronary artery disease patients before and after percutaneous coronary intervention(PCI). Methods 30 cases who were diagnosis coronary artery diseases(CAD) by coronary angiography, mean age 56±9 years old. All the patients who had no antiplatelet aggregation contraindication, were treated with standard anti angina pectoris drugs. Before PCI, all the patients took clopidogrel 75 mg per day. Activated platelet membrane CD40L express rate was measured by flow cytometry before and after PCI 6 hours. Results Activated platelet membrane CD40L express rate were 3.73±2.15 and 2.46±0.90, respectively in 30 patients before and after PCI 6 hours. Activated platelet membrane CD40L express rate was significantly decrease after PCI 6 hours than that before PCI(P<0.01). Conclusions Clopidogrel has significance effect on platelet membrane CD40L in coronary artery disease patients undergoing PCI. Clopidogrel can suppression platelet activation and prevent thromboembolism event occurrence.     

蛇床子总香豆素止喘作用机理探讨

蛇床子总香豆素具有松驰由药物引起的支气管痉挛和直接扩张支气管的作用,这一作用均能被β-受体阻滞剂心得安所阻断。此外,蛇床子总香豆素对麻醉动物无加快心率和升高血压的作用。提示蛇床子总香豆素的解痉作用可能是通过兴奋β₂-受体所致。     

Isoflavonoids from Astragalus mongholicus protect PC12 cells from toxicity induced by L-glutamate

lsoflavonoids, formononetin, 9,10-dimethoxypterocarpan 3-O-beta-D-glucoside, ononin, calycosin 7-O-glc and calycosin, were isolated from the roots of Astragalus mongholicus Bunge (Leguminosae). The neuroprotective roles and direct antioxidant effects of these isoflavonoids were investigated by using PC12 cell model and DPPH (1,1-diphenyl-2-picrylhydrazyl) assay. Formononetin, ononin and calycosin were found inhibiting glutamate-induced cell injury, with an estimated 50% effective concentration (EC50) of 0.027 microg/ml, 0.047 microg/ml and 0.031 microg/ml, respectively. Pretreatment with them increased the activities of antioxidant enzymes, including superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px), and prevented the release of lactate dehydrogenase (LDH) in glutamate-injured PC12 cells. On the other hand, calycosin 7-O-glc and calycosin showed more scavenging activity to DPPH radicals than formononetin in the cell-free system. The inconsistency between the neuroprotective capabilities of isoflavonoids and their directly scavenging activity to DPPH radicals indicated that formononetin, ononin and calycosin probably depended on increasing endogenous antioxidant and stabilizing the cells' membrane structures to inhibit the cell damage induced by glutamate.     

《武威汉代医简》“大黄丹”考证

《武威汉代医简》简50有关大黄一药,学界有两种意见:一是释作"大黄肉",指除去粗皮的大黄;一是释作"大黄丹",指断面呈红色的大黄。根据《武威汉代医简》"肉"、"丹"二字的书体特征,指出其当释作"大黄丹"。进而通过分析《武威汉代医简》偏正式词汇的构成特点,发现其俱是前偏后正式结构,指出将"大黄丹"解释作断面呈红色的大黄,有悖《武威汉代医简》惯例。通过考察汉代炼丹术及《神农本草经》、《名医别录》等本草著作以及《伤寒杂病论》、《肘后备急方》等方书,指出"大黄丹"当指"黄丹"。     

青果脂肪油的超临界CO2萃取及其GC—MS测定

本文应用超临界CO_2萃取技术对青果(Canarium album)进行脂肪油的提取,并用GC/MS联用技术测定了其中脂肪酸的成分及其相对含量,结果除主要成分与文献基本一致外,十六烯酸、亚麻酸、花生酸、花生烯酸及山嵛酸为首次在青果中发现。     

Collagen derived species-specific peptides for distinguishing donkey-hide gelatin (Asini Corii Colla)

Objective: As an important food therapy product with traditional Chinese medicine (TCM) applications, donkey-hide gelatin (Asini Corii Colla, ACC) has been used for thousands of years. However, till now no effective strategy had been proposed to distinguish ACC from other animal hide gelatins, especially closely related horse- and mule-hide gelatins, which was an embarrassment of ACC quality control. Methods: Combined mass spectrometry and bioinformatic methods have been applied to identify and verify two ACC-specific peptides (Pep-1 and Pep-2) capable of distinguishing ACC from other closely related animal gelatins with high selectivity. Results: It confirmed that these two peptides could be not only used for distinguishing ACC from highly homologous horse-hide and mule-hide gelatins as well as other animal hide gelatins. Conclusion: The present study provides a simple method for species-specific peptides discovery, which can be used for assessing the quality of animal gelatin products, and ensure they are authenticable and traceable.     

细胞膜生物色谱法在中药研究中的应用

中药的效应——物质基础研究一直是中药研究重点和难点，细胞膜生物色谱技术近年来在中药中应用逐渐受到关注，本文对细胞膜生物色谱法的原理、特点、应用现状进行了阐述，对其在中药研究的优势、存在的问题及对策、应用前景进行了分析和展望。通过该方法在中药效应成分分析中的不断应用，以及在实验过程的对该方法不断的完善和优化，细胞膜生物色谱法一定会在中药效应成分的研究中发挥重要的作用。