混合动力车型燃油箱晃荡声的时变响度评价方法与降噪应用

随着市场对汽车舒适性要求的提高,燃油箱油液晃动噪声问题越来越受重视。尤其是对于混合动力乘用车型,由于缺少发动机怠速噪声的掩蔽效应,更容易引起市场用户对燃油箱晃荡声的抱怨。该文以某搭载皮带驱动起动发电机混合动力SUV车型的燃油箱晃荡声问题为案例,系统性地进行了整车测试分析与路径排查工作,结合非稳态的晃动等效动力学模型,阐述了油液晃动瞬时冲击现象的潜在机理,提出了油箱壁面与形貌优化改进的思路;同时,通过对比分析声压级与响度指标方法的差异,说明了采用时变响度声品质指标能够更准确地反映出车内人耳对晃荡声的主观评价感受。该文主要通过“结构声”传递路径的优化,降低了油箱晃动激励到车内的传递,显著改善了车内的油液晃荡声问题,这对提升燃油系统NVH性能集成开发的能力,有着较重要的工程参考价值。     

油松籽油脂的提取及其脂肪酸组成与含量的评价

采用索氏提取法提取油松籽中的油脂,得油率为42.9%;对油脂进行甲酯化处理后用气相色谱-质谱联用仪检测其中的脂肪酸组成及含量。实验结果表明,油松籽油中含有7种脂肪酸,分别为肉豆蔻酸10.38%、硬脂酸3.05%、油酸21.98%、亚油酸(13,16-十八碳二烯酸)3.53%、亚油酸(9,12-十八碳二烯酸)38.38%、亚麻酸20.06%和二十碳三烯酸2.62%,其中饱和脂肪酸含量为13%,不饱和脂肪酸含量为87%。     

多普勒振镜正弦调制多光束激光外差二次谐波测量微冲量

提出了一种正弦调制多光束激光外差二次谐波测量微冲量的新方法,将激光与工质靶作用产生的微冲量转化为扭摆的转动角度测量,基于激光外差技术和多普勒效应,把待测转角信息加载到外差信号的频率差中,经信号解调后可以得到待测转角值,通过多次测量取平均值的方法可以提高待测转角的测量精度,从而提高微冲量的测量精度。利用这种新方法,以PVC+2%C为工质靶,利用MATLAB仿真测量了激光与工质靶作用产生的微冲量,结果表明：该测量的最大相对误差小于0.8%。     

Copper-linked 1T MoS2/Cu2O Heterostructure for Efficient Photocatalytic Hydrogen Evolution

Metallic 1T phase molybdenum disulfide(1T MoS₂) is an excellent catalyst due to the abundant active sites and good conductivity. However, complex synthesis and unstable nature of 1T MoS₂ still limit its practical application. Herein, we propose a simple method to trigger the phase transition of MoS₂. This phase transition is first predicted by density functional theory(DFT) calculations and then confirmed by Raman spectroscopy and high-resolution transmission electron microscopy(HRTEM). 1T MoS₂/Cu₂O heterostructure catalyst is then developed, showing enhanced photocatalytic hydrogen evolution.     

Narrowly-Distributed Conjugated Polymers Synthesized through Suzuki Polymerization with Palladium(II) N-Heterocyclic Carbene Complex Confined in Dendritic Mesoporous Silica Nanoparticles

A catalytic heterogenous Suzuki polymerization method was developed by confining the Pd(II)-catalyzed cross coupling reactions to take place exclusively in the nanochannels of dendritic mesoporous silica nanoparticles. Conjugated polymers with various monomer combinations, including donor-acceptor structures, were obtained in high yields. The molecular weights of the obtained polymers were well controlled with narrow molecular weight distributions (PDI value down to 1.13). All the polymeric products were highly soluble in common organic solvents, granting them with high processability. All the features of this confined Suzuki polymerization method endow the conjugated polymers great potential in optoelectronic applications.     

木质素对木质素-脲醛共聚树脂的影响及反应机理

通过调控甲醛与尿素摩尔比, 降低脲醛树脂胶黏剂中游离甲醛的含量, 以生物质玉米芯为原材料, 用碱液提取得到的碱木质素溶液与甲醛和尿素进行三元逐步共聚, 弥补降低醛脲比带来的胶合强度的快速下降问题. 以降低游离甲醛含量同时兼顾胶合强度为原则进行探索, 得到最佳实验条件为甲醛与尿素摩尔比(F/U)为0.91∶1, 木质素添加量为20%(质量分数), 在此条件下木质素-尿素-甲醛共聚树脂(LUF)胶合强度为0.99 MPa, 游离甲醛含量为0.26%. 对共聚树脂进行了结构表征, 表明木质素参与到反应中, 并能提高树脂的热稳定性和耐水性, 同时对反应的机理进行了讨论.     

Co-Assembly of Gd(III)-Based Metallosurfactant and Conjugated Polymer Nanoparticles in Organosilica Cross-Linked Block Copolymer Micelles for Highly Efficient MRI and Fluorescent Bimodal Imaging

Conformity of two biological imaging entities, magnetic resonance imaging (MRI) and fluorescence imaging, is achieved through co-assembly of a Gd(III)-based metallosurfactant, conjugated polymeric nanoparticles, and amphiphilic block copolymer F127 (PEO₁₀₆PPO₇₀PEO₁₀₆) followed by crosslinking with organosilica. The cross-linked micelles with a size around 100 nm exhibit outstanding dispersion stability in aqueous and phosphate buffered saline solutions, bright fluorescence emission, and high relaxivities, providing a new approach to synthesize highly efficient bimodal contrast agents. The relaxivities of the co-assembled micelles are synergistically enhanced by incorporation of Gd(III) complexes with high hydration number (q = 3) and elongation of rotation correlation time to achieve r₁ values up to 105.37 mm ⁻¹ s⁻¹ (at 1.5 T), which is over 20 times that of clinically used MRI contrast agents and among the highest values of all the nanoparticular MRI contrast agents. The external PEO layer endows these micelles with very low cytotoxicity for both in vitro and in vivo imaging. Meanwhile, thanks to the enhanced permeability and retention effect originating from their nanoscale sizes, the bimodal contrast agents show a prolonged blood circulation time in vivo and targeted accumulation at tumor regions to display outstanding MRI imaging performance.     

Mass preparation of nanofibers by high pressure air‐jet split electrospinning: Effect of electric field

A novel electrospinning method using airflow, namely high pressure air‐jet split electrospinning, was proposed to fabricate polymer nanofibers with ultrahigh production rate. 7 wt % polyacrylonitrile spinning solution with a 0.157 Pa s viscosity was divided into micron size droplets by the filter screen in the front of the nozzle, and then these droplets were divided and split through high pressure airflow, which were drafted into nanofibers directly in the electric field and airflow field. In this study, the electric field distributions with different positive electrodes were simulated and their effect on fiber formation was investigated. The results show that electric field distribution and its intensity depended on electrodes area, a broader electric field distribution with a stronger intensity would bring about a larger cone angle of spraying jet region, at the same time, the contrast in the spray region enhanced. When the whole nozzle was charged, thinner fibers with about 170 nm could be prepared and the fiber production was 75.6 g/h. Compared with the conventional needle electrospinning, the throughput of nanofibers could be improved by thousands of times based on this novel electrospinning method. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2014 , 52, 993–1001     

Cu-catalyzed oxidation of indoles to isatins

The first example of Cu-catalyzed oxidation of indoles to isatin derivatives by the use of cheap aqueous tert-butyl peroxide as an oxidant was developed. This methodology is practically convenient and highly functional group tolerant, allowing a variety of indole derivatives to transform into the corresponding isatin derivatives in good yields.     

Rapid identification of chemical composition and metabolites of Pingxiao Capsule in vivo using molecular networking and untargeted data-dependent tandem mass spectrometry

Pingxiao capsule (PXC) is a herbal medicine used for adjuvant therapy in breast cancer. However, the constituents and absorbed components of the formula and their related metabolites have not been elucidated to date. PXC is a typical traditional Chinese medicine formula consisting of Strychnos nux-vomica L., Curcuma wenyujin Y. H., Agrimonia pilosa Ledeb., Toxicodendron vernicifluum, Trogopterus dung, alumen, potassium nitrate (saltpeter) and Citrus aurantium L. In this study, a ultra-high performance liquid chromatography system equipped with high resolution Q-Orbitrap mass spectrometry (MS) and comparative Global Natural Product Social molecular networking together with the Compound Discoverer software were used to identify metabolites of PXC in vitro and in vivo. Based on untargeted data-dependent MS² and data-mining techniques, 89 peaks of alkaloids, flavonoids, organic acid and phenolic compounds were identified in a PXC 70% methanol extract. Furthermore, 15 absorbed prototype compounds and their metabolites were rapidly confirmed in rat blood. Glucuronidation, oxidation, methylation and hydroxylation were the main metabolic pathways. We fully clarified the chemical constituents of PXC and provided a scientific and efficient strategy for rapid discovery and identification of prototypes and their metabolites in rat plasma using high-resolution MS aided by Global Natural Product Social and Compound Discoverer software.