Numerical and experimental investigation on stochastic dynamic load of a heavy duty vehicle

Numerical simulation and field test are used to investigate tire dynamic load. Based on multi-body dynamics theory, a nonlinear virtual prototype model of heavy duty vehicle (DFL1250A9) is modeled. The geometric structural parameters of the vehicle system, the nonlinear characteristics of shock absorber and leaf springs are precisely described. The dynamic model is validated by testing the data, including vertical acceleration of driver seat, front wheel, intermediate wheel and rear wheel axle head. The agreement between the response of the virtual vehicle model and the measurements on the test vehicle is satisfactory. Using the reliable model, the effects of vehicle speed, load, road surface roughness and tire stiffness on tire dynamic load and dynamic load coefficient (DLC) are discussed. The results demonstrate that the proposed model can offer efficient and realistic simulation for stochastic dynamic loads, so as to investigate vehicle road-friendliness.     

金属-5-Br-PADAP螯合物的高效液相色谱分离

高效液相色谱法,通常是作为有机物分离测定的有效方法。近年来,国内外将其用于金属离子的分离测定研究亦渐增多。2-(5-溴-吡啶偶氮)-5-二乙氨基苯酚(简称5-Br-PADAP)能与大多数金属离子形成灵敏的有色螯合物。目前虽有应用此试剂高效液相色谱分离测定贵金属和测定钒(Ⅴ)、钴(Ⅱ)、铁(Ⅱ)的报导,但不能同时分离铜(Ⅱ)和铁(Ⅲ)。本文采用反相色谱,     

用硫酸软骨素A作探针共振瑞利散射及共振非线性散射法测定蛋白质

在pH 1.8～2.5的Britton-Robinson (BR)缓冲介质中, 硫酸软骨素A (CSA)的硫酸酯基离解而以带多个负电荷的大阴离子存在, 而人血清白蛋白(HSA)、牛血清白蛋白(BSA)、糜蛋白酶(Chy)、溶菌酶(Lyso)和α-淀粉酶(α-Amy)等蛋白质处于其等电点(pI)之下, 则是带多个正电荷的大阳离子, 两者可借静电引力、氢键作用、疏水作用而结合形成复合物. 此时将引起共振瑞利散射(RRS)和二级散射(SOS)、倍频散射(FDS)等共振非线性散射(RNLS)的显著增强并出现新的散射光谱. 3种散射的散射增强(ΔI_RRS, ΔI_SOS和ΔI_FDS)均在一定范围内与蛋白质的浓度成正比, 方法具有高灵敏度. 三种方法对蛋白质的检出限分别为4.5～12.0 (g/L (RRS法)、8.9～15.8 (g/L (SOS法)和13.4～31.5 (g/L (FDS法), 其中以CSA-BSA体系灵敏度最高(检出限可达4.5 (g/L). 研究了反应体系的RRS, SOS和FDS的光谱特征、适宜的反应条件和影响因素, 讨论了反应机理、结合模式以及散射增强的原因. 并以CSA-BSA体系为例考察了共存物质的影响, 表明方法有良好的选择性. 方法可用于正常人血清及尿样中蛋白质的测定.     

曙红Y分光光度法测定盐酸异丙嗪

在弱酸性NaAc HCl缓冲介质中 ,盐酸异丙嗪与曙红Y、赤藓红、乙基曙红等卤代荧光素类染料反应 ,形成离子缔合物。溶液颜色发生明显变化 ,其中曙红Y体系则发生显著的褪色作用 ,最大褪色波长为 5 16nm ,ε为 2 .73× 10 4 L·mol- 1 ·cm- 1 ,此外在 5 4 8nm处出现一个较低的吸收峰 (Δλ =32nm)。因此 ,本文采用曙红Y褪色光度法测定盐酸异丙嗪。其浓度在 0～ 1.5× 10 - 5mol/L范围内遵守比尔定律。方法灵敏度较高 ,选择性好 ,操作简便快速。用于片剂、针剂和伤风止咳糖浆中盐酸异丙嗪的测定 ,结果满意。     

Study on the interaction between torasemide and 12-tungstophosphoric acid by resonance Rayleigh scattering and resonance nonlinear scattering spectra and its analytical applications

In pH 0.6-1.1 HCl-NaAc buffer solution, torasemide (TOR) reacted with TP to form a 3:1 ion-association complexes. As a result, not only the absorption spectra were changed, but also the intensities of resonance Rayleigh scattering (RRS), second-order scattering (SOS) and frequency doubling scattering (FDS) were enhanced greatly. The maximum RRS, SOS and FDS wavelengths were located at 370, 333, 776 nm, respectively. Under given conditions, the intensities of RRS, SOS and FDS were all directly proportional to the concentration of TOR. The detection limits of RRS, SOS and FDS were 0.7173 ng mL(-1), 7.007 ng mL(-1) and 10.90 ng mL(-1). The optimum conditions and the effects of coexisting substances on the reaction were investigated. The results showed that the method had good selectivity. Therefore, a highly sensitive, simple and quick method has been developed for the determination of TOR. The method can be applied satisfactorily to the determination of TOR in tablets and urine samples.     

A dual-wavelength overlapping resonance Rayleigh scattering method for the determination of chondroitin sulfate with nile blue sulfate

To date, there is no study on bioethanol processing-induced changes in molecular structural profiles mainly related to lipid biopolymer. The objectives of this study were to: (1) determine molecular structural changes of lipid related functional groups in the co-products that occurred during bioethanol processing; (2) relatively quantify the antisymmetric CH₃ and CH₂ (ca. 2959 and 2928 cm⁻¹, respectively), symmetric CH₃ and CH₂ (ca. 2871 and 2954 cm⁻¹, respectively) functional groups, carbonyl CO ester (ca. 1745 cm⁻¹) and unsaturated groups (CH attached to CC) (ca. 3007 cm⁻¹) spectral intensities as well as their ratios of antisymmetric CH₃ to antisymmetric CH₂, and (3) illustrate the molecular spectral analyses as a research tool to detect for the sensitivity of individual moleculars to the bioethanol processing in a complex plant-based feed and food system without spectral parameterization. The hypothesis of this study was that bioethanol processing changed the molecular structure profiles in the co-products as opposed to original cereal grains. These changes could be detected by infrared molecular spectroscopy and will be related to nutrient utilization. The results showed that bioethanol processing had effects on the functional groups spectral profiles in the co-products. It was found that the CH₃-antisymmetric to CH₂-antisymmetric stretching intensity ratio was changed. The spectral features of carbonyl CO ester group and unsaturated group were also different. Since the different types of cereal grains (wheat vs. corn) had different sensitivity to the bioethanol processing, the spectral patterns and band component profiles differed between their co-products (wheat DDGS vs. corn DDGS). The multivariate molecular spectral analyses, cluster analysis and principal component analysis of original spectra (without spectral parameterization), distinguished the structural differences between the wheat and wheat DDGS and between the corn and corn DDGS in the antisymmetric and symmetric CH₃ and CH₂ spectral region (ca. 2994–2800 cm⁻¹) and unsaturated group band region (3025–2996 cm⁻¹). Further study is needed to quantify molecular structural changes in relation to nutrient utilization of lipid biopolymer.     

Absorption,Fluorescence and Resonance Rayleigh Scattering Spectra of Interaction of Papain with Calf Thymus DNA

In weak acidic medium, interaction between papain and calf thymus DNA (ctDNA) resulted in absorption spectral change, fluorescence quenching of papain and remarkable enhancement of resonance Rayleigh scattering (RRS). The interaction types and binding modes were discussed by characteristics of RRS, absorption, fluorescence and circular dichroism spectra combining thermodynamic data. Four interaction types include electrostatic attraction, hydrophobic force, hydrogen bonding and aromatic stacking interaction. Papain interacted with the major groove of ctDNA. Aromatic stacking interaction is the main reason of change of absorption spectrum and fluorescence quenching of papain. Surface enhanced scattering effect, resonance energy transfer effect, increase of molecular volume and conformational change make contribution to RRS enhancement. The enhanced RRS intensity (ΔI) is directly proportional to the concentration of ctDNA or papain. The detection limit (3σ) is 5.2 ng·mL^?1 for ctDNA and 5.6 ng·mL^?1 for papain. This creates conditions for determination of papain and ctDNA.     

Study on the interaction of CdTe quantum dots with coumaric acid and caffeic acid based on fluorescence reversible tune

This paper describes the synthesis of CdTe quantum dots (QDs) together capped by glutathione and thioglycolic acid (GSH and TGA) in aqueous solution. The narrow photoluminescence (fwhm ≤ 40 nm) CdTe QDs, whose emission spans most of the visible spectrum from green through red, has a quantum yield (QY) of 68% at room temperature. GSH/TGA-CdTe QDs are characterized by various experimental techniques such as optical absorption, photoluminescence and AFM measurements. Coumaric acid and caffeic acid is able to quench the fluorescence of GSH/TGA-CdTe QDs, and the fluorescence intensity is linearly proportional to the concentration of quenchers. The addition of bovine serum albumin (BSA) restores the fluorescence intensity of GSH/TGA-CdTe QDs-coumaric acid system and GSH/TGA-CdTe QDs-caffeic acid system. The fluorescence recovery was due to the interaction of BSA with coumaric acid and caffeic acid, leading to the freeing of the GSH/TGA-CdTe QDs. The fluorescence quenching mechanism of GSH/TGA-CdTe QDs was discussed. The binding constant and thermodynamics parameters of BSA-coumaric acid and BSA-caffeic acid during the binding process were calculated in the paper.     

Novel Glutathione-Capped Cadmium Telluride Quantum Dots-Based Off–On Fluorescence Sensor for Highly Sensitive and Selective Monitoring of Histidine

A novel glutathione-capped cadmium telluride quantum dots-based fluorescence “off–on” sensor was designed and applied for highly sensitive and selective monitoring of histidine in aqueous solution. To provide a platform for histidine detection, manganese ion was first employed as an effective quencher to decrease the fluorescence of glutathione-capped cadmium telluride quantum dots because of the binding of manganese ion to glutathione on the surface of quantum dots and the electron transfer from the photoexcited glutathione-capped cadmium telluride quantum dots to manganese ion. Due to its high binding affinity with manganese ion, histidine can make the manganese ion to be dissociated from the surface of glutathione-capped cadmium telluride quantum dots to form more stable complex with histidine in solution, and set free the luminescent glutathione-capped cadmium telluride quantum dots, thereby recovering the fluorescence of glutathione-capped cadmium telluride quantum dots. Experimental results showed that the recovered fluorescence intensity was directly proportional to the concentration of histidine in the range of 0.006 to 465.0 µg mL^?1 with a correlation coefficient (R) of 0.9977, and the detection limit (3σ/K) was 1.82 ng mL^?1. Relevant experiments also revealed that the fluorescence sensor gives excellent selectivity for histidine over other common amino acids. To further investigate perfect analysis performance, this sensor was utilized to determine histidine in synthetic samples with satisfactory results.     

分数阶Duffng振子的超谐共振

研究了含分数阶微分项的Duffing振子的超谐共振,通过平均法得到了系统的一阶近似解. 提出了超谐共振时等效线性 阻尼和等效线性刚度的概念,分析了分数阶微分项的系数和阶次对等效线性阻尼和等效线性刚度的影响. 建立了超谐共振解的幅频曲线的解析表达式和稳定性判断准则,对分数阶Duffing振子与传统整数阶Duffing振子的超谐共振解进行了比较. 最后通过数值仿真研究了分数阶微分项的参数对超谐共振幅频曲线的影响.