固体火箭发动机振动试验夹具优化分析与研究

通过相同激励条件下对三种典型振动试验夹具进行宽频段随机振动试验分析,发现夹具在试验频段内出现不同程度的共振现象,过试验现象严重。通过三种典型振动试验夹具质量、一阶固有频率、位移变化量及应变变化量等数据对比、分析,得出影响振动试验夹具振动传递特性的主要因素,以影响因素为优化变量,以典型部位平均响应与输入的振动传递比为优化目标,进行拓扑优化设计,最终经过夹具振动试验验证,过试验情况得到有效控制,满足相关规范要求,为固体火箭发动机振动试验控制提供保障。     

Chemical Modifications on Linen for Unsaturated Polyester Composites

Linen was chemically modified by oleoyl chloride(OC) and stearoyl chloride(SC) to graft fatty moieties onto fiber via ester connections. Pyridine was used as solvent. The reaction was simplified by reacting the compounds in air at 60℃ for 6 h. Fourier transform infrared spectroscopy(FTIR) and thermal gravimetric analysis were conducted to characterize the treated fiber. The FTIR result confirms that the fatty portions have been successfully grafted onto the fiber after the chemical modification. The thermal stability of the SC-modified linen(SCL) was similar to that of the flax modified by oleoyl chloride(OCL). SCL and OCL demonstrated a temperature of 5% mass loss, which was above 200℃ and could meet the requirements of the processing conditions for most composites. Thereafter, the SCL-reinforced unsaturated polyester(UPE) composites were prepared and characterized. The composite presented a much better impact strength of 61.1 J/m and tensile modulus of 1.69 GPa than those of UPE with applicable thermal stability. SCL has been shown to be a promising choice as reinforcing material for composites.     

城市隧道穿越复合地层的合理微差时间间隔

以莞惠城际项目的“上软下硬”复合地层条件为依托,结合现场测试数据,采用理论与数值分析相结合的手段,开展城市隧道穿越复合地层中合理微差时间间隔的研究。研究结果表明:复合地层中微差爆破效果较好,第1、2炮适宜的微差时间间隔为50~70 ms;围岩条件相同,振动波形和主震相的持续时间均随着爆心距的增加而变长;而围岩条件变差时,振动波形更易出现波形叠加现象;随着微差时间间隔增加,第1、2炮产生的主震相逐渐分离,在0~35ms间降震率波动明显且整体上小于稳定降震率;在复合地层中,两测点爆心距相同时,成洞区上方测点受空洞效应影响显著,振速明显偏大。     

Fabrication of Ag nanodot array over large area for surface-enhanced Raman scattering using hybrid nanoimprint mold made from AAO template

We demonstrated the fabrication of dense hexagonal arrays of Ag nanodots over a large area using a novel nanoimprint-based fabrication technique for surface-enhanced Raman spectroscopy. Flexible imprint molds with sub-10 nm features were duplicated from AAO templates using a novel hybrid mold technique. This method solves the nonflatness-induced defect issue in the conventional thermal nanoimprint technique, and allows high-quality duplications of nanometer features from rigid nonflat templates. Moreover, with the help of the excellent tunability of the size of nanoholes on AAO templates, we were able to tune the size of Ag nanodots, and consequently to tailor the resonance frequency of the Ag nanodot arrays. Finally, surface-enhanced Raman scattering of Rhodamine-123 on Ag nanodot arrays was measured, and large signal enhancement was observed on the 70 nm Ag nanodots. We numerically simulated the optical properties of those Ag nanodot arrays, and excellent agreement was found with the experimental results.     

Coexisting four-wave mixing and six-wave mixing in three-level atomic system

We demonstrate the coexisting four-wave mixing (FWM) signal and six-wave mixing (SWM) signal which can be enhanced both by electromagnetically induced transparency (EIT) and optical pumping effect in a common three-level and open four-level inverted-Y type systems of ⁸⁵Rb. We also analyze the effect of optical pumping in different energy level systems by arranging laser beams and comparing the strength of the increased and reduced absorption caused by optical pumping.     

Effects of a natural prolyl oligopeptidase inhibitor, rosmarinic acid, on lipopolysaccharide-induced acute lung injury in mice

Rosmarinic acid (RA), a polyphenolic phytochemical, is a natural prolyl oligopeptidase inhibitor. In the present study, we found that RA exerted potent anti-inflammatory effects in in vivo models of acute lung injury (ALI) induced by lipopolysaccharide (LPS). Mice were pretreated with RA one hour before challenge with a dose of 0.5 mg/kg LPS. Twenty-four hours after LPS was given, bronchoalveolar lavage fluid (BALF) was obtained to measure pro-inflammatory mediator and total cell counts. RA significantly decreased the production of LPS-induced TNF-a, IL-6, and IL-1β compare with the LPS group. When pretreated with RA (5, 10, or 20 mg/kg) the lung wet-to-dry weight (W/D) ratio of the lung tissue and the number of total cells, neutrophils and macrophages in the BALF were decreased significantly. Furthermore, RA may enhance oxidase dimutase (SOD) activity during the inflammatory response to LPS-induced ALI. And we further demonstrated that RA exerts anti-inflammation effect in vivo models of ALI through suppresses ERK/MAPK signaling in a dose dependent manner. These studies have important implications for RA administration as a potential treatment for ALI.     

Active role of hydrogen bond and ambient water in Meyer–Schuster rearrangements in high‐temperature water

Meyer–Schuster rearrangements of 2‐phenyl‐3‐butyn‐2‐ol with H₃O⁺ and (H₂O)₆ model in high‐temperature water (HTW) have been investigated by the use of density functional theory calculations. In the substrate 2‐phenyl‐3‐butyn‐2‐ol catalyzed by H₃O⁺ and (H₂O)₆, the Meyer–Schuster rearrangements were predicted by the frontier molecular orbital theory. The results show that the rearrangement does not involve the carbonium ion intermediates, but the first transition state is carboniumion like. Dehydration and hydration may occur via the intermolecular proton relay along the hydrogen‐bond chains and the second step of reaction path is a total acid–base catalytic process. Based on the results, a model considered both HTW ambient and water molecules are proposed to represent mechanisms of other reactions in HTW. © 2011 Wiley Periodicals, Inc. Int J Quantum Chem, 2011     

Tissue Distribution Study of Poloxamer188 in Rats by Ultra-High-Performance Liquid Chromatography Quadrupole Time of Flight/Mass Spectrometry with MSALL-Based Approach

Poloxamer188 (PL188), as one of the most commonly used pharmaceutical excipients, has unique physicochemical properties and good biocompatibility, and so is playing an increasingly extensive role in the field of medicine. Currently, there are few studies on the tissue distribution of PL188 in vivo. In this study, the LC-MS method based on MS^ALL technique of quadrupole time of flight mass spectrometry for absolute quantitative analysis of poloxamer 188 in biological substrates was established for the first time. The tissue distribution of poloxamer188 in SD rats were studied using the established quantitative analysis method. To explore the distribution of PL188 in organs and tissues, PL188 was administered via rat tail vein at a dose of 5 mg/kg. Eight kinds of tissues including heart, liver, spleen, lung, kidney, stomach, muscle and brain of rats were collected at 0.25 h, 1 h and 4 h after administration. Tissue distributions showed the highest level was observed in kidney, then in stomach, which indicated PL188 mainly bioaccumulated in the kidney. This study can provide references for the further study of PL188.     

氢离子选择性液膜超微电极的研制

本报道新的以三－十二烷基胺（ＴＤＤＡ）为载体和以对氯苯硼四－十二铵（ＥＴＨ２１９１）为载体的ｐＨ微电极膜，与原有的ＴＤＤＡ膜相比较，新的ＴＤＤＡ膜和ＥＴＨ２１９１膜制备更加容易，膜内阻从原有的２×１０＾１１Ω（１μｍ）下降到３．５×１０＾１０Ω（１μｍ），其中ＥＴＨ２１９１膜的动力学响应ｐＨ范围为１２～４．５，与原有的ＴＤＤＡ膜（ｐＨ范围为１２～５．５）比较，拓宽了１个ｐＨ，而且ＥＴＨ２１９１膜